Honda Insight Forum banner

241 - 260 of 293 Posts

·
Registered
Joined
·
6,193 Posts
MCU rear mount mod

I've mentioned a few times in this thread how I thought 'MCU' material - microcellular urethane - would probably work for the rear motor mount. Well I finally came across something to work with, made some inserts - and so far it seems to work very well... I'm still kind of dialing-in the implementation, but I think I've got something that works at least as good as stock on NVH, and better than stock in terms of actual performance... My main gripe with the stock mount is that it's too springy - that sling-shot feel on launch, major shudder and judder in reverse, especially if backing-up on a hill, just too much slop. On top of that, of course, we know that they're weak and crack and break, and then you have to replace the whole mount for like $120 or so...

So, I found some huge MCU bump stops for something like a Chevy Suburban or Avalanche and they more or less fit the stock aluminum housing with only minor modifications. They come in a pair and I got them for about $36 (I see they're typically being sold for around $45).


The length needs to be trimmed on both bump stops and you're left with two halves that look like your typical polyurethane bushing inserts. You reuse the OEM aluminum spacer and housing.


What's interesting is that initially the dimensions don't quite add up and it seems like they won't work. The outside diameter seems a bit too small, as does the hole for the spacer. But the spacer can be worked into the small hole without drilling it out - the material is soft enough to stretch and flex - and the pre-load this imparts probably makes it work better since the outside diameter is a bit too small to completely fill the OEM housing. The whole thing is interesting because very small design differences make big differences in the performance. I've tried 4 different setups at this point with minor variations in how I put it all together, and the results are a range of performance, from very tight and sturdy feeling with probably a bit too much NVH, to pretty sturdy (sturdier than stock) with little to no added NVH and in some usages actually smoother than stock...

This image shows how I made a shim out of rubber floor mat (an old Honda Fit mat) to fill-up the space in the housing (it's about 3.5mm thick). This shim plus rubber washers to take up the ~3mm of space on either side of the spacer, when inserts are fully pressed in, was my first iteration. It was the tightest, but it also added NVH, mainly a slight rumble at idle and high load/low RPM acceleration.


I tried no washers at the ends of the spacer, just letting the inserts 'float', but I didn't like the way the inserts wiggled out of the housing bore. But even that implementation felt fine...

I finally ended up removing the rubber shim entirely and putting hard washers at the ends of the spacer. They fit around the outside diameter of the spacer, just thick enough to fill-up the space left at the ends of the spacer with inserts fully inserted, sticking out a little so that when the mount is installed and torqued, the fork-ends put a bit of pressure on the insert material and keep them centered and pressed into the housing. With the rubber shim removed, there's little to no contact between the housing and the insert at rest - which is good in terms of NVH, because it ends up accommodating the movement of the engine at idle. I can barely feel the engine movement at idle. Yet, I don't really feel much slop on launch either, or any rumble during acceleration. Reverse up hill is way smoother and solid with this setup than with the stock mount...
 

·
Registered
Joined
·
6,193 Posts
(cont...)



Not sure I like the crappy steel washers here; I think nylon would be better and would do the job. But in general, this seems to be close enough. For a tighter mount, some kind of shim in the housing might be better, maybe 1mm thick, maybe 2mm. I think there needs to be some play between the insert outer diameter and housing inner diameter, though, to accommodate the engine shake at idle, as well as reducing NVH on acceleration. Either that or the spacer hole needs to be drilled out larger so there's no pre-load on the insert, and then I think you'd probably still need to do something else. I think the 'no shim' option greatly reduces NVH on acceleration as well, and I think this is because only part of the insert - the back part and probably some of the side material - is contacting the housing, rather than all of it. So, less vibration gets transmitted through the inserts to the housing... There's lots of ways this could be done/implemented and have the results be good...
 

·
Registered
Joined
·
6,193 Posts
^ I'm not sure whether your question is directed at my post or not because the MCU material isn't very "stiff," and because I addressed the issue raised by your question in my post. This is what I wrote:

....With the rubber shim removed, there's little to no contact between the housing and the insert at rest - which is good in terms of NVH, because it ends up accommodating the movement of the engine at idle. I can barely feel the engine movement at idle.
I'd add that I feel engine movement at idle less with this mod than with the OEM mount. But there's a couple caveats here: I had a couple pieces of crappy foam stuffed in the voids at the top of the stock mount. They were pretty old and compressed though, so I'm not sure to what extent they affected vibration at idle. Also, I have my IMA disabled at the moment. This alters normal operation in 2 ways - it raises the idle speed from about 900 to 1100-1200, and supposedly the IMA has an engine vibration smoothing function at idle, which might be disabled if the IMA is disabled. But I've never been able to discern to what level or extent there is such an IMA smoothing function...

I put this post in this old-running thread because there's a long history of trying to find a solution to the rear mount problems, and I see value to 'keeping it all' in one place. The drawback with that though, in this day and age, is that some people might miss the point, starting from the beginning and thinking 'polyurethane engine mounts' per se is the most germane topic... So Sam1234, if you're questioning the viability of strictly polyurethane material used as engine mounts, that question has been addressed in this thread early on - they suck big time, especially at the rear. You can't fill the rear mount with anything typical and expect less than truck-like NVH. It's truly horrible. I've filled with silicone and even that soft material imparts way too much NVH. But MCU is quite different, it's a foam and specifically engineered to damp vibration, noise, etc., yet it's very durable with excellent spring-like functionality (i.e. it has a low yet increasing spring rate as the material becomes more and more compressed)...

If anyone is disappointed in their stock rear mount functionality, I recommend they try this MCU mod. The parts to buy are Belltech 4925 bump stop kit, I've seen it available on Amazon prime and on ebay, very widely available...
 

·
Registered
Joined
·
4,008 Posts
This looks very promising! I might try it out if I hadn't taken my busted Mont to the recyclers when I moved a couple years ago...

Hopefully someone in the East coast will do this and bring it to the meet. The engine feeling like it's mounted on rubber bands has been my biggest complaint about the way the car drives/shifts.
 

·
Registered
Joined
·
1,008 Posts
Nice work! Glad it worked out for you. Just to clarify you're currently using the bump stops with the rubber wrapped around them? Or did you take the rubber out?
 

·
Registered
Joined
·
6,193 Posts
Rubber shim is out, as-is there's about 3mm of play between bushing and housing...

I'm probably going to add a shim about 1mm-2 mm thick. There's still a bit more of a slack feel than I'd prefer (yet still less than stock) and I'm wondering if I can dial that out without adding NVH. If you reduce the play between bushing and housing, you increase the chance of transmitting mostly idle vibrations, but also low RPM/high load vibrations/rumble. Not sure...

There's a lot of dialing-in, tuning, that can be done to adjust the rigidness vs. NVH performance. Just that I'm not positive which aspects of the implementation affect what and how - it takes a lot of work to do trial and error - jacking up the car, loosening the CAT, removing the mount, make your change, put it back together. Right now I'm trying a few things that don't involve additional modification of the inserts themselves, as I want to avoid having to buy more if a change takes me in the wrong direction... In general, though, I'm thinking the hole in which the spacer goes should be bigger, there's probably a little too much pre-load on the bushing, you lose some 'spring rate travel' with the spacer so tight in the hole...

In addition to contact between bushing and housing 'in the middle', there's also contact between the sides/'hat' portion and the sides of the housing. Not sure if that needs to be tight or loose or how tight and how loose. I think there's a twisting motion under forward acceleration load, and the sides get loaded. Question is, how much do the sides need to accommodate movement/vibration in order to eliminate NVH yet still remain rigid, get rid of slop?...

I replaced the big metal washers at the sides with ABS DIY jobbers yesterday, a little thicker but a little smaller in diameter. I don't think that made much difference in performance, so I'd prefer plastic washers vs. steel to circumvent galvanic corrosion... My sense is that there does need to be washers at the sides, though, to at minimum keep the inserts centered on the spacer/boss.

One alternative is to simply trim insert length a little less, so that when the halves are pressed together to form that single bushing, total bushing width equals at minimum total width of the spacer/boss, i.e. there's no extra space at the ends of the spacer when inserts are installed. The 'hat' portions wouldn't butt-up against the housing sides though, and so the engine would be mostly free to slide left to right between the hats. That's sort of what happened when I didn't use any washers, but since I trimmed inserts to fit such that hats butted-up against housing sides, one insert half simply wiggled out of the housing until it hit the fork-mount portion of the whole mount setup. I'm not sure how important it is to keep the mount perfectly centered; my feeling is that there needs to be some force to keep it as perfectly centered as possible... Also, I think there needs to be some centering force to keep the mount-feel rigid, just not so much that a lot of NVH gets transmitted to the housing... I also tried soft washers at the sides (~3mm slices from the original MCU material), I may go back to that, maybe that plus a shim. The soft washers I'm pretty sure had the least NVH so far, just that I can't say how the rigidity of the soft washer setup compares to what I have now...

Etc etc. It's interesting, kind of complicated when you get down into the details.

I got my IMA back online, closed things up, and went for a drive. It seems pretty clear that my current setup beats the stocker across the board. I couldn't find any aspect that was worse than stock, and there was quite a few aspects that are better. At the lower idle speed that the IMA allows, I do feel a very slight vibration, but I don't think it's any worse than stock. There might be a couple engine speed/load conditions that have additional rumble, maybe, but in general this setup feels smoother in many more circumstances/conditions than stock. For example, somewhere around 2000 RPM at high load, accelerating, there used to be more rumble with stock, now it's smooth...

Right now I'd prefer a little more tightness. There's still a slight oscillation when ON and OFF throttle... I don't recall having that with my first iteration, with the rubber shim and rubber washers at ends of spacer. Yet as I mentioned, there was too much NVH with that setup. So something in between is needed, which I sort of have now, just that, I need to move a little more in the direction of the first setup... I mean, I could leave it as-is and it'd be perfectly fine, but since I'm into this now it'd probably be best to just push a little farther, now...
 

·
Registered
Joined
·
6,193 Posts
BTW, if there's a couple people who might want to try this out, I think I'd be open to doing it for them (i.e. modding their old OEM mount) if they send me their old mount plus enough to buy the bump stops plus maybe some relatively modest compensation... No guarantees though. PM me if you're interested... I think turn around would probably be around a week or two...
 

·
Registered
Joined
·
1,008 Posts
I'm glad it's an upgrade for you. I remember when I first filled my rear mount with poly people were throwing all kinds of negativity.
 

·
Registered
Joined
·
6,193 Posts
Someone pm'd me a question about the diy MCU mount,. Thought it'd be good to post here:

read your whole thread twice. Well done. Never could figure out what NVH stood for other than some kind of vibration. I plan to do the mod to at least the rear mount ASAP. And possibly to the other two as well. What about using stainless washers to reduce galv potential or the labor intensive fabricator
Ion of aluminum washers?
NVH - Noise Vibration and Harshness

I ended up using a drill-attached hole saw, drilled some circles in some 1/8" PVC plastic sheeting I had lying around [actually, I think I used ABS pipe], created some decent-thickness plastic washers. You could probably do something similar with ABS or PVC drain pipe, or whatever, just warm with a heat gun to flatten-out and make sure the thickness is right - should be enough to take up the space left over at the ends of the spacer with inserts pressed together, plus about 2mm to exert a little pressure on the flanges of the spacers. I couldn't find any nylon washers at say Lowe's. I never quite honed-in on whether plastic vs. metal washers made a difference in terms of NVH, I don't think it did (I tried plastic, metal, and soft MCU washers)... Aluminum would probably be fine.

But there does need to be some washers - the inserts need to be trimmed to a length that allows the flanges to press against the sides of the housing, which leaves space on the spacer that needs to be taken up by washers. I tried no washers, with inserts trimmed less, without insert flanges pressed against housing sides, and it allowed side-to-side movement that caused some bad stuff. The insert flanges need to keep stuff centered yet provide enough flex to absorb NVH under load...

I tried probably about 2 dozen different configurations, very minor differences yet some of them make a big difference in the outcome... I ended up drilling the center bore in the inserts a little bigger, plus I drilled 3 holes through the side to help compliance (a bit more flex under load), but I'm not positive these really did anything necessary. In the end, after drilling out the center hole, I had to put duct tape around the spacer to make it tighter in the hole I had just drilled out, for instance - so I don't think it's necessary to drill out the hole.

Hard to explain, the outside diameter of the inserts don't quite fill the aluminum housing hole - but as it turns out, you need to have slack, you need to have a couple mm of space between the outside diameter of the inserts and the housing. Otherwise, you get too much NVH at idle. There needs to be slack... It's hard to press the stock spacer into the insert hole, it's super tight. But, it can be done (lube the hole with something that won't stay there, like wire pulling cable lube or spit). The tightness ends up expanding the outside diameter of the inserts, and I'm pretty sure that's what we want...

In the end, the most important things, I think, are:

1) make sure you have a bit of space between outside diameter of inserts and housing,
2) make sure insert flanges are - not necessarily tight against, but up against - the sides of the mount housing.

Not sure if tighter is better or not, as the tighter they are, the higher the risk of transmitting NVH. But on the flip side, the tighter the flanges press against the sides of the mount housing, the less movement you'll get. As it stands with my current setup, my flanges are up to the sides but not pressed tightly against them. I get a little more movement than I'd prefer, but going tighter might ruin the relatively excellent NVH performance I have now. It was hard to dial that in...

3) make sure your front motor mounts and the rear mount are aligned as perfectly as possible. You shouldn't have to use a lot of (any) force to align the rear mount mount-to-body bolts after you've threaded the thru-bolt through the spacer and inserts and lightly tightened...

Also, I had to lubricate the outside surface of the inserts, surfaces that touch the aluminum housing. It was mainly the flanges rubbing against the aluminum - that started making squeaky-rubbing noises at idle...

The propensity for noise to get clearly transmitted from the rear mount to the cabin is huge. A tiny bit of noise ends up, just, going everywhere. I think the floorpan acts a bit like a loudspeaker - vibration at the mount goes right through the bolts, into the floorpan, vibrates the floorpan, and spreads into the air...
 

·
Registered
Joined
·
6,193 Posts
More PM'd questions:

From various comments in threads on the center mount, it sounds to me like the engine at rest hangs in a relatively neutral position of strain relative to that mount. Correct? Also, with the stock mount setup of a flexible poly web bonded to both elements of the mount, any aspect of your replacement is at least the equal of the original in terms of vibration and noise as far as I can tell at this point. So, are we talking degrees of improvement over the original in all this discussion? Lastly how difficult is removal of the old black poly from the metal parts of the mount?
First off, the OEM mounts are rubber rather than 'poly'. It's not too difficult removing the old stuff. Use a propane torch indirectly to burn the bonding agent. This is really easy on the center boss, tougher on the housing. You'll probably want to cut out the center boss and rubber in a gross manner, first. Just cut the 'arms' with a hacksaw blade or utility knife. Then shoot the flame into the boss (spacer) hole. It will probably only take a minute or two to heat it up enough to start burning the bonding agent; you should see a lot of white smoke, and the rubber will start to bubble up and peel back. Then it will just fall off when pulled. It will leave behind a brittle, crusty layer of stuff that you can just sand off with fine grit sand paper or the like...

Getting the remaining rubber off the housing is more difficult because the housing sucks up all the heat. You need to move the torch flame all around the outside of the housing, trying as best you can to get even heat dispersion... I think it took me maybe 10 minutes to get it hot enough to burn the bond. Same thing applies here as with the boss, though - you should see a lot of white smoke and keep it going until you think the bond has been burned off and broken... Needless to say this is smelly stuff so do it in a well-ventilated area, such as outside... Avoid direct heat on the rubber itself - it will just burn and smell really bad yet not break the bond between the aluminum and rubber.

....it sounds to me like the engine at rest hangs in a relatively neutral position of strain relative to that mount. Correct?
I think that's the way it's supposed to be, particularly at the rear mount. I'm not as sure about the fronts. At idle the engine/drivetrain oscillates about a mm or two, so to minimize NVH the rear mount needs to accommodate that movement - i.e. the center portion of the mount should be able to move about a mm or two without touching the housing, otherwise it will vibrate against the housing and go through the floor pan. The stock mount doesn't have a full gap, of course, but the minimal size of the rubber arms is in part meant to achieve the same thing...

On NVH performance of my DIY MCU mod vs. OEM? I'd say it's better across the board. The NVH characteristics are a little different. As I recall, the stock has more vibration and noise at certain loads/engine speeds. There might be a couple junctures at which the MCU mod performs only as good, I can't really think of anywhere where it does worse though. It's noticeably better at 2000+ RPM under load. It's the worst in the 1500-2100 RPM range, yet I don't think it's worse than stock. The overall feel, tightness, is better across the board...
 

·
Registered
Joined
·
1,738 Posts
Rubber shim is out, as-is there's about 3mm of play between bushing and housing...

I'm probably going to add a shim about 1mm-2 mm thick. There's still a bit more of a slack feel than I'd prefer (yet still less than stock) and I'm wondering if I can dial that out without adding NVH. If you reduce the play between bushing and housing, you increase the chance of transmitting mostly idle vibrations, but also low RPM/high load vibrations/rumble. Not sure.
How is your bump stop motor mount holding up so far?

My 100% Silicone rear mount has been getting more and more not so good after a few years. It looks good but the shudder on starting to move from a stop is really bad now.

I plan on trying your bump stop version. I have some ~1mm thick flexible plastic "hose" that was used to drain pools. That may work as the shim you mention above. If your setup works I'll change my website article on the motor mount to just link to this page.

What did you use to cut the excess length of each bushing off so the cut is parallel to the other bump stop when assembled? Is a small gap OK or should there be no gap at all?

The picture you posted of 1 stop in the alum holder looks very smooth but maybe that bushing hadn't been cut yet.

I'm thinking of mounting one stop on the spacer tube and chucking the spacer itself in my lathe if the stop centers up properly. If nothing else I can mark where the cut should be.

Maybe use a box cutter to do the actual cutting?
 

·
Registered
Joined
·
6,193 Posts
How is your bump stop motor mount holding up so far?
Holding up fine, no problems...

I plan on trying your bump stop version. I have some ~1mm thick flexible plastic "hose" that was used to drain pools. That may work as the shim you mention above....
I don't think we need the shim (I'm not using one). As long as you don't drill-out the center hole for the boss, the MCU insert will stretch, expand enough to fill-out the aluminum mount housing bore. There will be a mm or 2 of slack, but you need that...

What did you use to cut the excess length of each bushing off so the cut is parallel to the other bump stop when assembled? Is a small gap OK or should there be no gap at all?
I used a 'chop saw' (10" compound miter saw) with I think a 60 tooth 'fine' cutting blade (not sure if it's 60, but it's the number of teeth commonly above the 40 tooth blade). Use a piece of 4x4, 'strap' the big end of the insert to the 4x4, then swing down and chop. There should be a picture in my photogallery of the same process on the poly insert I did for my control arms... Here's a link to that, there's a few pics: https://www.insightcentral.net/forums/members/164984-eq1-albums-control-arm-polyurethane-insert-mod.html

There shouldn't be a gap. You should try to cut them to the length that will allow the two insert halves to slightly compress against one another - yet leaving the 'ears', the 'flanges' NOT tightly compressed against the aluminum mount housing. So, basically, that means the distance from the inside edge of one 'ear' to the inside edge of the other, when the two inserts are pressed together on the boss, should be slightly wider than the width of the aluminum mount... Kind of hard to explain.

I guess it's not that big a deal. It's just that, I'm pretty sure that if the 'ears' compress hard against the mount when it's all put together, it causes more NVH at idle. So you want the inner portions of the inserts to butt-up against one another when pressed together, before the 'ears' butt-up against the mount sides. Yet, at the same time, you want the 'ears' to be right up to the mount sides - not compressed, but just grazing. The ears need to prevent too much lateral movement under load. Yet if they're compressed too tightly against the mount sides at rest, then you get more NVH at idle... Hope that makes some sense.

Overall, I think the easiest, most straight forward approach, unlike what I did, is to do nothing extra - no holes drilled through the sides, no shims, nothing. Just buy the inserts, cut them to the right length, press the boss through, a very tight fit, make or buy some plastic washers to take up the rest of the space on the boss - ideally those should be thick enough to compress the outside side of the 'ears' a couple mm...
 

·
Registered
Joined
·
1,738 Posts
Holding up fine, no problems...
I don't think we need the shim (I'm not using one).

OK, no shim needed.

I used a 'chop saw' (10" compound miter saw) with I think a 60 tooth 'fine' cutting blade (not sure if it's 60, but it's the number of teeth commonly above the 40 tooth blade).

I wasn't sure if the stop material would cut smoothy even with a knife. I would guess that if I push the metal sleeve into the stop with with enough of the metal showing to clamp in my lathe chuck that I can cut the stop with a lathe cutoff blade or if necessary a hacksaw while the lathe is running.

There shouldn't be a gap. You should try to cut them to the length that will allow the two insert halves to slightly compress against one another - yet leaving the 'ears', the 'flanges' NOT tightly compressed against the aluminum mount housing. So, basically, that means the distance from the inside edge of one 'ear' to the inside edge of the other, when the two inserts are pressed together on the boss, should be slightly wider than the width of the aluminum mount... Kind of hard to explain.

Good explanation, I can run with that. Once I figure out where the cut needs to be made I'll post a picture or two for others to use (with the dimension I used).

[edit]I goofed and used my old Razr V3 as the camera & since it's so old the software I used to use to move the pictures to my computer won't work anymore. The only visible change from eq1's pictures is my 3" diameter washers I made.[/edit]


I guess it's not that big a deal. It's just that, I'm pretty sure that if the 'ears' compress hard against the mount when it's all put together, it causes more NVH at idle. So you want the inner portions of the inserts to butt-up against one another when pressed together, before the 'ears' butt-up against the mount sides. Yet, at the same time, you want the 'ears' to be right up to the mount sides - not compressed, but just grazing. The ears need to prevent too much lateral movement under load. Yet if they're compressed too tightly against the mount sides at rest, then you get more NVH at idle... Hope that makes some sense.

Perfectly clear now.

Overall, I think the easiest, most straight forward approach, unlike what I did, is to do nothing extra - no holes drilled through the sides, no shims, nothing. Just buy the inserts, cut them to the right length, press the boss through, a very tight fit, make or buy some plastic washers to take up the rest of the space on the boss - ideally those should be thick enough to compress the outside side of the 'ears' a couple mm...
Sounds like a winner. I'll order the bump stops today.

I have a sheet plastic & aluminum collection, I'll go with aluminum for longevity.

I made a small press using a 2-1/2 ton bottle jack and some 4" wide channel iron. Hopefully it's tall enough to press the sleeve into the stops.

Your suspension bushing post looks very good. I've saved that thread in case I need it later.

Thank you.
 

·
Registered
Joined
·
1,738 Posts
Using eq1's instructions I rebuilt my rear motor mount with
the GMC #4925 bump stops.

Short version of this post:
BINGO & perfecto!!

eq1 outdid himself in figuring this method out and documenting the simple solution. This is a noteworthy event in keeping our cars on the road. Thank you from the bottom of my motor mount. :)
----

As usual I changed a few things:
1. Using my lathe, I reduced the outside diameter of the aluminum 3" sleeve by ~0.2" (total) to not stretch the 1/2" hole in the bump stops so much. I also slightly chamfered the ends of the sleeve to ease inserting it into the bump stops.
2. Because of 1. I used a single, 3" wide layer of blue pool drain "hose" (0.026" thick) as a spacer placed around the interior of the motor mount housing before inserting the bump stops inside the alum housing. This still allows 0.104" (~2.6mm) clearance all around the bump stops and the housing. If you don't modify the sleeve you probably don't need to use the pool hose.
3. After a lot of calculations and measurements I made two 3" diameter, 1/8" thick aluminum washers to press the bump stop flanges lightly against the side of the alum mount housing.

Construction details:
I used an oxygen-acetylene torch to heat the housing to remove the original pieces of the rubber mount with a 1" wide paint scraper. I then used a ~2" diameter wire brush in my drill press to clean up the remaining black mess inside the mount housing. Don't use much force to prevent scratching the interior of the housing.

The lathe removed the rubber from the sleeve.

I also used the lathe to cut the bump stops and make the spacer washers. A normal short length of galvanized 1/2" steel water pipe fits into the bump stop holes tight enough to use a X-ACTO knife to cut the bump stop by hand rotating the lathe 3 jaw chuck. The surface of the cut surface looks like sliced bread though.

I applied a small amount of silicone mold release to the inside of the bump stop holes to ease inserting the sleeve with my drill press.

Overall impression of the new rear motor mount:
For the first time in 6 years of driving my Insight I do not have clutch shudder when moving off from a stop. There is NO unusual vibration or noise associated with my bump stop motor mount. I tried lugging the engine in different gears at slow speeds and the car just runs smoothly as you would expect it to. Having the AC ON at an idle is also OK if the idle speed is ~1100 RPM or slightly higher.

My 100% Silicone caulking (band aid) worked OK for ~4 years but I always had slight shudder until the clutch fully engaged. That's gone and eq1's method should last much longer.
---

The worst part of the whole job is getting the top two bolts of the engine mounted portion of the rear motor mount unscrewed if you don't move the exhaust system out of the way.

Naturally I also forgot to loosen the long sleeve hold down bolt -before- loosening any of the other bolts. But I finally got it loose by clamping the nut in a vise and using a 5 FOOT piece of pipe, as an extension, slipped over a socket "breaker bar"!

Word to the wise, loosen the sleeve bolt first before removing the mount and tighten it last after bolting the [new] motor mount parts back on the car.

Here's an interesting thing I found out while doing this conversion. If you hold the stripped motor mount part that bolts to the engine near the 4 bolt holes and lightly strike one of the arms with a metal tool it rings like a tuning fork with a pleasant, long lasting sound.
 

·
Registered
Joined
·
6,193 Posts
Glad it worked out...

Here's an interesting thing I found out while doing this conversion. If you hold the stripped motor mount part that bolts to the engine near the 4 bolt holes and lightly strike one of the arms with a metal tool it rings like a tuning fork with a pleasant, long lasting sound.
I noticed that too a while back. I wondered if it was coincidence or whether it had something to do with having the 'fork' tuned to reduce some resonance.
 

·
Registered
Joined
·
59 Posts
Hey guys. Quick response. If you are going to remove the rear engine mount, remove battery, remove the three 14mm bolts holding the battery tray (armed looking frame side to side), pull armed frame away from firewall so you can unbolt battery box (4 10mm bolts) and remove box. Now the top two 14mm engine mount brace bolts can be removed easily. Of couse, the other bolts remove from under the car.
Moon car
 

·
Registered
Joined
·
59 Posts
Any photos of engine mount?

Using eq1's instructions I rebuilt my rear motor mount with
the GMC #4925 bump stops.

Short version of this post:
BINGO & perfecto!!

eq1 outdid himself in figuring this method out and documenting the simple solution. This is a noteworthy event in keeping our cars on the road. Thank you from the bottom of my motor mount. :)
----

As usual I changed a few things:
1. Using my lathe, I reduced the outside diameter of the aluminum 3" sleeve by ~0.2" (total) to not stretch the 1/2" hole in the bump stops so much. I also slightly chamfered the ends of the sleeve to ease inserting it into the bump stops.
2. Because of 1. I used a single, 3" wide layer of blue pool drain "hose" (0.026" thick) as a spacer placed around the interior of the motor mount housing before inserting the bump stops inside the alum housing. This still allows 0.104" (~2.6mm) clearance all around the bump stops and the housing. If you don't modify the sleeve you probably don't need to use the pool hose.
3. After a lot of calculations and measurements I made two 3" diameter, 1/8" thick aluminum washers to press the bump stop flanges lightly against the side of the alum mount housing.

Construction details:
I used an oxygen-acetylene torch to heat the housing to remove the original pieces of the rubber mount with a 1" wide paint scraper. I then used a ~2" diameter wire brush in my drill press to clean up the remaining black mess inside the mount housing. Don't use much force to prevent scratching the interior of the housing.

The lathe removed the rubber from the sleeve.

I also used the lathe to cut the bump stops and make the spacer washers. A normal short length of galvanized 1/2" steel water pipe fits into the bump stop holes tight enough to use a X-ACTO knife to cut the bump stop by hand rotating the lathe 3 jaw chuck. The surface of the cut surface looks like sliced bread though.

I applied a small amount of silicone mold release to the inside of the bump stop holes to ease inserting the sleeve with my drill press.

Overall impression of the new rear motor mount:
For the first time in 6 years of driving my Insight I do not have clutch shudder when moving off from a stop. There is NO unusual vibration or noise associated with my bump stop motor mount. I tried lugging the engine in different gears at slow speeds and the car just runs smoothly as you would expect it to. Having the AC ON at an idle is also OK if the idle speed is ~1100 RPM or slightly higher.

My 100% Silicone caulking (band aid) worked OK for ~4 years but I always had slight shudder until the clutch fully engaged. That's gone and eq1's method should last much longer.
---

The worst part of the whole job is getting the top two bolts of the engine mounted portion of the rear motor mount unscrewed if you don't move the exhaust system out of the way.

Naturally I also forgot to loosen the long sleeve hold down bolt -before- loosening any of the other bolts. But I finally got it loose by clamping the nut in a vise and using a 5 FOOT piece of pipe, as an extension, slipped over a socket "breaker bar"!

Word to the wise, loosen the sleeve bolt first before removing the mount and tighten it last after bolting the [new] motor mount parts back on the car.

Here's an interesting thing I found out while doing this conversion. If you hold the stripped motor mount part that bolts to the engine near the 4 bolt holes and lightly strike one of the arms with a metal tool it rings like a tuning fork with a pleasant, long lasting sound.
Any photos to show?
Moon car
 

·
Registered
Joined
·
1,738 Posts
Glad it worked out...

I noticed that too a while back. I wondered if it was coincidence or whether it had something to do with having the 'fork' tuned to reduce some resonance.
I really doubt it. If you touch one of the two arms the tone stops immediately.

When the arms are bolted to the sleeve I can't imagine that there would be any resonance affect that could effect the engine mounting.

It's too bad that Honda didn't use two short bolts screwed into the sleeve so the actual mount housing could then be removed by just unbolting the 2 sleeve bolts and the 2 bolts holding the housing to the floor of the car.

I was tempted to make a steel sleeve with 2 short mounting bolts and reduce the weight of the black tuning blob to compensate for the added bolts, lock washers and steel sleeve weight. Maybe next time if I ever have to remove the mount again.
 
241 - 260 of 293 Posts
Top