Engine snail mount bush alternative

[Janis]

Deep in garage boxes found BMW e36 front suspension arm bush.
Fits exactly into snail mount (~4mm thinner).
Centre cylinder have to be used from old X19 bush. It fits too good, so I put a thin layer of wd40 can between bush and centre cylinder.
In link part nr6
http://www.realoem.com/bmw/enUS/showparts?id=CF91-EUR-02-1995-E36-BMW-325tds&diagId=31_1251

Not sure if they have different stifness between 1.6 compact and 2.5 touring(but this one with cast iron block is the heaviest one, springs definitely are different)

 

[Dr.Jeff]

Nice discovery! Thanks Janis.

The BMW part number is: 31129059288. At a quick glance it appears to be the same part number for pretty much all 3 series models. I found them listed online for less than $5 each, although they are commonly sold in pairs on eBay for under $12 (for the pair) with free shipping.

BMW front suspension bushings of this type are very robust and given they are for a heavy front-engine vehicle they will offer more than enough support for the snail mount. So this should prove to work well as an inexpensive alternative to replacing the entire snail mount.

The BMW part listing indicates the dimensions as: 60mm OD, 33mm wide, and 18mm ID. So when you say the BMW item is "4mm thinner", that refers to the 'width' (as in the stock bushing is about 37mm wide)? And if you put the metal inner sleeve from the stock Fiat bushing into the BMW's metal inner sleeve, that makes the OD for the Fiat sleeve about 18mm? Or was the Fiat sleeve a little smaller than that (you added a thin shim there)? [Just making sure I understand correctly]

Fiat once offered just the bushing as a replacement item to be installed into an existing snail mount (part number: 4466363), however it does not seem to be available. One vendor has a listing for such an item at around $22, but they state part number 4218081 which is the Fiat number for a 128 complete snail mount. So I'm not certain if it is the correct part? Otherwise the complete mount for the X1/9 (4466362) usually sells for around $60 to twice that (depending on mark-up).

 

[AKimball92]

I know I bought a snail mount bushing without the cast part for my build. If I remember, I can dig through my receipts to see where it came from. Its still in the baggy as I will have to take advantage of my work to get it pressed in. Or since they are rare enough, I might hold off until absolutely needed.

 

[Janis]

Yes, I put a shim between. I pressed it in with my fingers and could move it back and forth, that’s why I used a shim.

Anyway I would not suggest cheap ebay things. Those OE bushes lives ~20years on BMW, I prefer febi or Lemforder.

It would be better to use PU aftermarket bushes - they are stiffer and quiet cheap.

Asked how much that bush would cost with metal cylinder inside to local PU parts manufacturers.

 

[Dr.Jeff]

Agree about using better quality brands. Even those are roughly only $12 (USD) each from my suppliers.
Urethane bushes can transfer a lot of vibration (noise) through to the chassis. Great for track use but a bit annoying on the street. And best used when all of mounts are replaced with urethane, to avoid unnecessary stress on any one component.

A possible alternative to adding a thin shim for the inner sleeve is to use a bearing sealant. This is a liquid similar to a thread locker but thicker and engineered to secure metal bearing races when they have too much clearance. One nice thing about using this bushing is that it retains the Fiat inner sleeve; that makes it a perfect fit for the bolt and the width of the mounting tabs on the frame.

I like this idea, thanks again.

 

[myronx19]

Quick question though, won't the motor slide over to one side on the sleeve? I had a new motor mount pop out where the rubber is pressed into the snail, and that caused the snail to hit the body.

 

[Janis]

Quick question though, won't the motor slide over to one side on the sleeve? I had a new motor mount pop out where the rubber is pressed into the snail, and that caused the snail to hit the body.

View attachment 5651

It will tend to do taht
I put a shim between to lock that connection - if it wont help - will try DrJeff's advice or will put another two elements on each side to avoid that.

 

[Dr.Jeff]

On my stock snail mount, the rubber has 'stretched' to one side allowing the mount to rest against the body tab on that side (I think that is what you are describing). I think part of that is allowed when the 'dog-bone' mount gets soft and the engine moved toward one side.

But I see your point; if this BMW bushing is slightly narrower than the Fiat item, then it might move that much further. Perhaps a flat rubber disc/shim could be placed on either side of the bushing, as Janis suggests. VW did this on some engine mounts.
These:

Go on either side of these:

 

[Janis]

FIY
Local quality parts manufacturer sells pair those e36 poly bushes for 28€..

 

[Dr.Jeff]

e36 poly bushes

Are they solid poly or do they have the 'cut-outs' like stock rubber design? If the poly is a "soft" formula and they have the air-gaps / cut-outs, then maybe they will offer enough "give" to avoid excessive vibration transfer.

Thinking more on Myron's comment about the mount migrating to one side (thanks again Myron for that, excellent call), perhaps a combination of a "bushing" and a "cushion" on each side will assure it does not. I'm thinking the "bushing" would be a firm material like nylon or similar, and its ID will fit over the inner metal sleeve while its OD will fit within the steel cylinder of the BMW mount...the width of it will fill the gap between the BMW mount and the "cushion". The cushion would be like the VW items I showed above; a softer disk of rubber/fiber or similar and fit between this nylon bushing and the body mounting tabs. The concept is the nylon bush prevents migration (keeping the mount centered), and the rubber cushion eliminates any rubbing of the nylon bush against the body. Actually the stock snail mount insert needs these also; as I mentioned my stock mount has migrated to one side and rubs against the body. With these bushings to locate the mount laterally, the center metal sleeve (stock Fiat part) will not need to be 'shimmed' or 'glued' in place...because it can't travel side to side.

These would fit something like this (see pic below): The nylon bush's width goes between the red arrows, and height between the yellow arrows. The rubber cushion fits between the blue arrows in width and the black arrows in height.

I guess this may sound a little complicated but actually it would be very simple to do. And as I said, the stock mount needs this anyway.

Janis, I like the 50 ton hydraulic press you used to get the BMW inserts mounted

 

[TonyK]

Looking at this post I see others are having similar issues with the snail mount bushing. When I did the engine swap for the Abarth engine I used the X1/9 snail mount and bushing. The location is different than the X1/9 engine, but the mount is the same. Here is a picture of the engine bay from the top.

I will not try and diverge to much on this thread but the issue became apparent when doing and inspection of the car and the Snail mount was found to be broken, This happened shortly after a reflash of the ECU was done bring power output to 177 HP. Without having to go back to the drawing board and come up with another design a new mount was fabricated from Stainless Steel. I have 2 trains of thought to why the mount failed. One was the increase in horse power, the other could be due to the massive size of the adapter plate mounted to the engine. It is made from a section of 1" aluminum plate 7" x 5". Possibly the coefficient of the aluminum expansion over stressed the mount can caused it to crack. I would love to hear from Bernice what her thoughts are on this failure.

Here is a picture of the mount that was in the engine and I installed another what appears to be serviceable bushing into the new mount that I made.

That unit is currently in the car and it too has collapsed.

Which brings me to the solution I have been working on. That being to cast my own Urethane rubber bushing.

The mold is made from 2 sections of Acetel rod. I must confess working in the mirror image was very confusing for me to make the mold halves. Also I didn't check my measurements closely and ended up with this mess, which has since been corrected.

As you can see the steel sleeve is not centered or proud. A little more turning in the lathe and this issue has now been corrected. The mold has been recast and I am waiting for the rubber to cure before I remove it from the mold.




I think this will work well for my application. The rubber is Task 16 and has a shore rating of 80A. The down side is the removal and salvaging of the old steel parts and cleaning them. Also the rubber has a very limited shelf life after opening. I purge the containers with argon to give it a little more storage time. I will post a few pictures once I have it out of the mold. It will be a few weeks before I can install it as I will be heading to Kentucky to Bob Martins as we start on our next project. Will do some posts from his location once we get into it a bit more.

TonyK.

Grimsby Ontario Canada.

 

[Dr.Jeff]

Nice work Tony, keep us informed of your assessment as it progresses.

If I understood correctly, the broken mount was after the Abarth swap and using the large aluminum adapter? Seems like there could be a lot of factors involved; difference in total weight placed on it, non-standard stress loads at various angles compared to stock, added leverage with the extended length of the adapter, misalignment issues, or even prior fatigue on the used mount. Hard to say. The fact the new rubber insert failed so quickly suggests the mount was not designed for the conditions it is now used in. So your upgraded design should help considerably.

How does this Task 16 rubber with shore rating of 80A compare with either the stock rubber or a polyurethane (which can be a few choices of shore ratings)? I'd like to get an idea of the relative "hardness" to estimate the 'ride quality' (so to speak). Thanks

 

[TonyK]

The issue of stock is a question that cannot be answered as the stock bushing now seems kind of soft and it distorts. The new bushing material certainly is more firm.

I felt that if it was too firm I would drill 2 3/8" holes through the bushing to allow some more give rather than installing voids in the mold. For my application I think it will work out well.

I have taken it out of the mold. Please see pictures.

TonyK.

Grimsby Ontario Canada.

 

[Janis]

Wow 9.86€, but of course not in the stock

 

[Dr.Jeff]

but of course not in the stock

Maybe never in stock...I find advertisements like that often, great price but no parts available. I wonder if it was ever in stock, or maybe just a couple at that price to get customer's attention.

 

[Matt Brannon - Midwest Bayless]

Wow 9.86€, but of course not in the stockView attachment 7656

Sorry to be debbie downer but that unit is for 1100cc motors without a front water jacket plate and cannot be bolted directly to a 1300 or 1500. You can tell by the outward shape of the bottom. It is solid on the backside does not have correct spaces to clear one of the 1300/1500 front water jacket bolts. I had a whole batch of 1100s like this once that needed to be machine clearanced in order to work. So I thought I would just push the bush out and put them in OE castings, but they were 1mm larger or smaller than stock and wouldn't work that way either! lol.

PS. I was not working with this particular mfg/vendors unit, I am speaking of 1100 style units in general.

 

[Janis]

Volvo v70 2001
2.4 petrol engine

This bush may fit also good

Dimensions on caliper are ~

 

[Jonohhh]

Howdy, just checking in to ask how the bushing is holding up? I'm currently putting an E36 LCA bushing in my snail mount and I am a little conflicted about the orientation I should install it.

The bushing is designed to be soft within a fairly tight range and then hit a (hard but not solid) travel limiter after some amount of deflection.

As oriented, I feel I should not put the left side up (the direction that the load is applied to) as there is nearly no travel before it hits the solid portion (meaning it would permanently rest on the stop and transmit extra vibration).

The right side being up is slightly better, as some travel is permitted, but it's soft enough to be deflected to the stop with my hands alone.

I'm considering putting top or bottom facing up as it's fairly stiff in that direction and should have enough rubber to still isolate vibrations fairly well. It's not designed to be loaded in that direction - but neither is it designed to be loaded consistently in the other direction as in the E36 it simply manages thrust loads from the front wheels.

Also, thank you Janis for the nice find, sourcing a Febi/Bilstein part was cake compared to the alternatives (especially considering the rush). Lemförder is my go to but this will likely hold up just the same.

 

[Janis]

Howdy, just checking in to ask how the bushing is holding up? I'm currently putting an E36 LCA bushing in my snail mount and I am a little conflicted about the orientation I should install it.

The bushing is designed to be soft within a fairly tight range and then hit a (hard but not solid) travel limiter after some amount of deflection.

As oriented, I feel I should not put the left side up (the direction that the load is applied to) as there is nearly no travel before it hits the solid portion (meaning it would permanently rest on the stop and transmit extra vibration).

The right side being down is slightly better, as some travel is permitted, but it's soft enough to be deflected to the stop with my hands alone.

I'm considering putting top or bottom facing up as it's fairly stiff in that direction and should have enough rubber to still isolate vibrations fairly well. It's not designed to be loaded in that direction - but neither is it designed to be loaded consistently in the other direction as in the E36 it simply manages thrust loads from the front wheels.

Also, thank you Janis for the nice find, sourcing a Febi/Bilstein part was cake compared to the alternatives (especially considering the rush).

View attachment 63079

Yes it is not suitable configuration for X, but I still use it.
There must be plenty of solid poly bushings for E36, which would be more suitable in a X

 

[Jonohhh]

Yes it is not suitable configuration for X, but I still use it.
There must be plenty of solid poly bushings for E36, which would be more suitable in a X

I'll give the alternate orientation an attempt to see how it holds up. It's not all that difficult to replace so worst case scenario I find a soft poly bushing at a later date or find something in the Lemförder catalog (thanks to dimensions now being known) from a common vehicle that works.

I was just checking to make sure it didn't immediately pose an issue!

Thanks again Janis!