[Insightful2]

Sorry, I never did report the final diameters. The stock mount I measure to be around 76 mm diameter, and my mount is just about 74.8 mm diameter. So I have taken roughly 1 mm out of the total diameter. With that said, I am currently rather happy with the current NVH and level of slop. It feels better than stock, and I am guessing things are well in check.

I still checked my upper mounts for reference, but I don't plan on changing them from what I saw. I grabbed the best pictures I could for reference, and this is what I have. I can see some favoritism to one side or another, but I don't see anything totally conspicuous. If you see anything odd, please let me know. I looked through the service manual recently, and I didn't see any special procedure suggested for aligning these things just right, but it is maybe somewhere else.

The pictures are in order from the trans side mount then the engine side. I have pictures of both sides of the mount for reference to the other side. These were the best pictures I could get without dismantling things in the way. Like I said, I don't see or feel anything conspicuous, so I am likely gonna leave these in place unless something stands out as irregular.

 

[eq1]

^ I can't really tell anything from those images. The second one looks to be pretty centered...

Sorry, I never did report the final diameters. The stock mount I measure to be around 76 mm diameter, and my mount is just about 74.8 mm diameter. So I have taken roughly 1 mm out of the total diameter.

Here are some measurements of a spare stock housing and MCU insert:
-OEM aluminum housing hole diameter, 76mm
-Belltech MCU insert: outside diameter 68.5mm, hole diameter 15.9mm/0.625"
-aluminum boss (tube) OD 24mm/0.95", ID 12.2mm/ 0.481"

Just sitting here with bare hands and a little spit for lube, I couldn't press the boss (tube) into the insert hole, otherwise I would have measured the insert outside diameter with the tube pressed in place, which would have stretched the insert outside diameter. You can see that the tube diameter (24mm) is about 8mm bigger than the insert hole (~16mm), so that's a tight fit to say the least, and there's a good deal of stretching that happens. Without that stretching the housing diameter (76mm) is about 7.5mm bigger than the unstretched insert diameter (68.5mm)...

I think ideally, if someone were 3D printing the housing the like you did, the tube would be smaller, so it'd be easier to fit in the insert hole and wouldn't stretch/pre-load the insert much, and the housing hole would be around 70mm -- it'd be just a tad bigger than the insert with the smaller tube pressed in place.

Not 3D printing a housing, you'd need the tight fitting boss and stretched insert, otherwise the insert doesn't fill the housing hole well enough.

 

[eq1]

I made a new MCU insert rear mount. I modified the previous one too much, in too many different ways, so I wanted to start from scratch, do the minimum, and see how it works. It works fine, even with trimming the insert halves too short. Previously I had said that the insert halves should be trimmed so that they touch in the middle and so that the 'ears'/flanges don't press too tightly against the aluminum housing. But I wasn't all that careful and ended up trimming them so that the 'ears' press tightly against the housing and yet the two halves don't touch in the middle... I don't feel that it makes much if any difference. I did lube them up good with Sil-Glyde. This version is better than my last, it's tighter, less prone to wayward vibrations, and in the end it didn't require any special modifications...

Just trim the halves, lube them up, press the boss/spacer through one half, insert into mount, press the other half on the boss, squeeze together, insert washers on the ends to take up the slack-space, lube the outside (any MCU that touches aluminum), install. It's not perfect, I still feel too much engine movement, but that's all in the front mounts. It still feels better than new stock units, though, and not as much NVH...

 

[Eli]

It's kinda funny, the OP of this thread is who I bought the 300k mile Citrus from, the one I took to the meet....

 

[olrowdy01]

^ I can't really tell anything from those images. The second one looks to be pretty centered...

Here are some measurements of a spare stock housing and MCU insert:
-OEM aluminum housing hole diameter, 76mm
-Belltech MCU insert: outside diameter 68.5mm, hole diameter 15.9mm/0.625"
-aluminum boss (tube) OD 24mm/0.95", ID 12.2mm/ 0.481"

Just sitting here with bare hands and a little spit for lube, I couldn't press the boss (tube) into the insert hole, otherwise I would have measured the insert outside diameter with the tube pressed in place, which would have stretched the insert outside diameter. You can see that the tube diameter (24mm) is about 8mm bigger than the insert hole (~16mm), so that's a tight fit to say the least, and there's a good deal of stretching that happens.
[snip]

I used my lathe to machine the tube diameter to be 0.2" less than stock. I was able to use my drill press to easily insert the tube into the bump stops with no trouble. I also used a little silicone grease inside the stops to make the insertion easier to do.

 

[eq1]

I used my lathe to machine the tube diameter to be 0.2" less than stock. I was able to use my drill press to easily insert the tube into the bump stops with no trouble. I also used a little silicone grease inside the stops to make the insertion easier to do.

It's pretty tight, tough pushing the stock spacer through the MCU insert hole, but that stuff stretches a lot, and once you get it going it's easy. If you make the spacer smaller, then the insert won't stretch out as much and will fill less of the housing... I don't know which is better, but in general I don't see a reason to do anything to the spacer... The through-bolt is big, there doesn't seem like much wiggle room for removing material. I think ideally one would probably find a smaller diameter spacer and a matching through-bolt, then you wouldn't have to muck around with removing the OEM bushing material from the OEM spacer to reuse. On the other hand, you'd still have to remove the OEM material from the housing to reuse the housing, and that's a lot tougher than removing the material from the spacer... So, ideally you'd probably do the 3D printed housing and find a smaller diameter spacer and matching through-bolt and nut, and not mess with the stock stuff at all - if 'easy' were a priority...

BTW, if anyone has old motor mounts they want to get rid of, certainly rear but fronts as well, I'd gladly pay shipping to get a hold of those. I'd like to do another rear one, but I'd also like to experiment with the fronts...

 

[eq1]

Came across some seemingly weird ebay motor mount options. Someone's selling used mounts with supposedly new bushings. I also came across an image where someone's selling the bushing inserts alone. I snipped an image. It shows the cavity in the front mounts where they'd be fluid-filled, thought that was interesting. Also shows how the rear mount insert is a rubber soft center in a metal, what's it called, a metal thing, 'aluminum cage':

 

[Sigma Projects]

Pretty cool stuff