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Polyurethane transmission mount

9K views 38 replies 9 participants last post by  J. Dub 
#1 ·
So I poured some poly into an extra trans mount I bought since everyone knows how much ours flex. I already had some 94A durometer stuff. Well, bad idea! Lol rattles my brain at 2K rpms. I'm sure it would be livable if the engine was smoother since I did this to my CVT and the engine is no where near as smooth as my 5MT. So hopefully tomorrow I'll have some time and drill out some holes and see how good it feels. But if anyone else tries this I highly recommend not doing 94A for a daily driver. Also the electric motor whine is much much more audible as well as a drone noise like having a subwoofer. Wonder if that's part of the properties of an aluminum chassis.


I think I will change the rest of the mounts and adjust the valves on this CVT before my teeth fall off.
 
#2 ·
Yea those mounts were designed to flex for that reason. I have seen people complain that the mounts 'don't last long enough'. To that, I say use polyurethane mounts, then come complain lol.
 
#3 ·
yea, it's just deceiving because the mounts will still be whole, but too pliable. I think I made the mistake thinking it was the rear tranny mount that needed strengthening at least that's what one tech told me. But it has fixed some of the issues like the engine bucking when accelerating or coming out of auto-stop and clunking noise when going over harsh bumps.

I just ordered some 60A durometer stuff to see how it will work out on the other mounts. There should be a sweet spot where drivetrain isn't allowed to move all over the place and still be comfortable. I bet Honda had a heck of time getting the in cabin noise levels down because of the aluminum chassis and the inherent vibrations from a 3 cylinder.
 
#5 · (Edited)
I bet Honda had a heck of time getting the in cabin noise levels down because of the aluminium chassis and the inherent vibrations from a 3 cylinder.
They expended a lot of effort on the engine mounts as several recent posts and quotes from Honda technical documents on this forum testify.
Filling voids with various compounds etc has been tried before with minimal success.
Yes it's nice and stiff but vibrates the hell out of the car/driver.

Sigma. We like to encourage experimenting and investigation so feel free to report back with how it goes.
But there is a massive amount of stuff on here already, and having a look at what has gone before can avoid you going down a dead end and/or reinventing the wheel.
 
#6 ·
You might want to check out this thread:
http://www.insightcentral.net/forum...-issues/19809-polyurethane-engine-mounts.html

I think it's the most complete to-date... I'm interested to hear the outcomes of using the 60A stuff. I kind of doubt it'll be acceptable, but knowing just what it feels like will give us a good, known value (i.e. 60A) to work from. I'd still like to find a hunk of micro-cellular polyurethane - the usually white-ish foam-like rubber material most suspension bump stops are made of these days. I think that stuff would work well -for the rear, but maybe even for all three mounts...
 
#7 ·
thanks guys. I will have read through the thread.

I imagine it's why a lot of the newer hondas have hydraulic mounts.

But I have no illusion that having stiffer mounts will result in less vibration. I'm just trying to find that point at which the car isn't bouncing all over the place and isn't rattling my teeth.
 
#8 ·
I'm sort of in the same boat. I think I'd willingly accept 'some' extra vibration in exchange for less slop... But I think we can still come up with an alternative that doesn't produce a net difference - it'd be like a one-for-one compromise - a little more 'high-end' vibration, yet a little less 'low-end' slop. In the end, the less slop is more important, to me at least...
 
#10 ·
A little update:

So I decided before I take the mount off I decided to drill holes in the bottom where I have access.

First attempt I drilled five 1/4" holes. Then tested it, felt like nothing changed. So then I got a 1/2" drill bit and made three larger holes where the previous holes I made. And progress! So still feels solid as far as auto-stop and reverse etc, but doesn't have massive vibrations at 2K rpms anymore. Now it only has some harsh vibrations around 1100~1300 rpms. Idle is smooth also from inside the cabin and this motor is not very smooth IMO. So What I figure is when I'm back at my buddy's shop I'll take it off and put another large hole up top and see how it feels after that.
 
#13 ·
#15 · (Edited)
Here's a couple other images of that Fit mount. It's cheaper... If it fit, do we think it might be better for any particular reasons?



Here's a stocker:


Assuming the 2 mounting holes at top align - which I'd guess is a long shot - you'd need some kind of spacers or shimming; the stock Insight mount has that offset, whereas the Fit mount is flush. Actually, you'd either have to hack the front and drop the front mounting point, or have spacers at the rear mounting point, the latter of which would shift the location of the 'boss' quite lower... The hole through the boss looks bigger than the Insight (though it's hard to tell for sure, different scale); if so might pose some challenges...
 
#17 ·
Also: how much longer will Honda have replacement mounts?

/my main concern.
 
#19 ·
The OEM Insight mount is going to dampen better than the Fit mount.
1) it's engineered precisely for the chassis harmonics at that mounting location
2) its aluminum frame absorbs vibration much better than steel
3) the rubber is also probably of a different durometer.

Another concern is locating the mount correctly so that the alignment and range of movement do not stress the other finely tuned components of the engine and the other mounting brackets. You don't want the works to be misaligned all the time.

That said, it'd be nice to see someone use the Fit mount. He'd probably need a welder to chop and splice it accordingly.
 
#20 ·
better is a subjective word. Maybe less comfortable but maybe won't let the engine slop around. Whatever the stock mounts are made of they feel like play dough and move around like no mount I've ever seen before.

I could have sworn aluminum carries vibrations more so than steel, like in the case of a steel vs aluminum driveshaft. Since aluminum is more rigid than steel and flexes less so harmonics flow through the chassis more easily. But, I could have been mislead, but that's just what I remember.

As far as mounting it, it depends on how everything lines up, it may need to be cut or a spacer added. If a spacer is all that is needed in the back then it may be good, but if it's needs to be cut and welded then probably becomes cost prohibitive.

But that's why I'm going with polyurethane and seeing what works.
 
#21 ·
Love Those Aluminum Wind Chimes

Sigma: Why are wind chimes not made of aluminum?

When you seek to re-engineer someone else's work, you need to approach it with a certain amount of humility and have respect for what the other guy has done and try to figure out what may have been overlooked or has changed since then.

The Honda Insight motor mounts are a superb example of fine tuning and a thoroughly engineered product.. It is impressive how quietly Insights move about at an Insight meet. Lots of cars and normal conversation.

Much of what is experienced as judder and chatter that is blamed on the Insight motor mounts is due to folks riding the clutch or a failed/non-functional IMA system. With the Honda Insight Hybrid, when getting underway, dump the clutch and apply foot pedal for adequate assist: no judder, no chatter. Drivers of low powered vehicles tend to ride the clutch starting out.

Honda Insight transmission mounts do fail prematurely in some cases, probably due to excessive vertical movement. Limiting the vertical movement should solve the problem. If we assume that the vertical movement is the problem, we may want to consider adding an external non-connected dash pot to limit the vertical movement with out tinkering with the satisfactory existing mount so that we do not goof up a good thing. Adding this type of external hydraulic dampener has been suggested early on years ago in the engine mount thread but no one has reported having tried it. I think it is worth a try if you are unhappy with the Honda engineered mount.
 
#22 ·
Try an aluminum tuning fork. We can go back and forth on alloys and uses in sound, but then we are getting into resonance instead of just transmission of sound. Usually sound travels through high strength aluminum faster than it does iron, steel or stainless. But yea soft cheap aluminum that's a different story, but I seriously doubt they are using that in the insight.

My experimentation is on my CVT since its mount is in worse condition than the 5MT. Nothing I can really do about driving habits that isn't out of the norm.

But, ever since I beefed up the mount a lot of associated problems I had before, ie. regen bounce, shuttering in reverse, harsh start up after auto-stop is gone.

So I'm happy with my progress so far. Take it as you like, I'm just sharing my findings with the forums.
 
#23 · (Edited)
the best mount would be something thats something like the suspension on the corvette, soft when the motors not flexing and rigid when shifting, rapid off throttle transition etc. an electrorheological solution.

reading: http://www.hindawi.com/journals/smr/2013/831017/
 
#25 ·
Thermactor : that would be awesome. I wonder how dampening will be in another 10 years, mounts in general have changed a lot in the past 10 years as it is.

Hugh: sorry if I came across annoying, really trying not be, I just like hands on stuff a lot.
 
#26 · (Edited)
It might have an (advanced!) DIY aspect, you just need to start with an existing hydraulic mount design and then fill it up with the electrorheological fluid solution and then program a board that takes engine RPM and throttle position inputs to adjust the dampening as needed
Neat stuff, but WAAAAAAAAAAAY more complex than just finding the ideal durometer material for remaking the donut mount! :D

Come to think of it, what would preclude the use of a pre-made electrorheological shock absorber as used in some GM cars, bolting it to the motor (you'll need to make the mounts), and then playing around with the electronic aspect?

This paper presents a review of all relevant papers known to the authors describing design, modeling, and control of electrorheological- and magnetorheological-based mounts. The material presented here indicates that substituting regular hydraulic fluid with ER or MR fluids can lead to a successful development of semiactive mounts. These types of mounts are desirable as they allow real time changes on the dynamic stiffness of the mount, shifting of the notch, and peak frequencies of the mount over a fairly wide range of frequencies. Such response is desired as new technologies, for example, engine on demand and pneumatic or hydraulic actuation, induce vibrations to the chassis over a wider range of amplitudes and frequencies. Optimal operation of MR and ER semi-active mounts requires a suitable control strategy which seems to elude the engineering community. Further research in the control area is needed to increase the potential of these mounts being adopted in more engineering applications.
 
#29 · (Edited)
#30 · (Edited)
If you could find the right size, the corrugated roll stuff, in 60A - it'd probably work, I think, maybe... If it were a stock size (which I doubt we could find, but 'if') and you got a long tube, you could just hack off donut-sized pieces. Might actually be cost effective. I looked around the website a bit but didn't see anything that caught my eye, that fit the bill... And the stock stuff I did see - like rods and large yet short tubes, were quite costly, surprisingly... If anyone wanted to pursue this I might be willing to chip in and experiment. Maybe I'll go out to the garage and take some measurements tomorrow - I have a spare mount from which I already removed the rubber part...

I wonder, do you or anyone else think we'd need to 'fix' the urethane insert into the aluminum mount hole by some means and/or how we should do that? For example, if we DID find a roll, we'd need to cut it to the width of the mount more or less, and then you'd press the urethane insert into the aluminum hole. And you'd press the boss/spacer into the hole in the insert. But if the insert were cut to the exact width of the aluminum housing, it might slip sideways. Doesn't seem like there would be much side load often, but there's probably some... Anyway, glue that into the aluminum? Or maybe cut a wider insert that fills up the entire space between the two ears that hold the aluminum housing in place - the insert would then basically be the same width as the boss/spacer. Just takes more material to do that, so maybe glue or something would work, or maybe glue the boss/spacer into the insert hole... Not sure I like that, seems like you'd want to allow rotation... Just throwing out some ideas in case anyone else feels like doing the same - 'brainstorming'...
 
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