Durability of aftermarket motor mounts

[Jake]

I don't understand what's so difficult about making these aftermarket mounts. They all fail for the same reason and nobody can figure out how to sink a metal pad into the urethane? If I didn't work 25hrs a day I'd have made these years ago. I'm just in awe at the recurring lack of ingenuity.

Jake

[UweM3]

maybe a tooling issue. Loads of cost and little batch numbers. How many of these mounts can you sell to justify making a moulding tool?

I can CAD you a design up in a few hours which would work but who is going to mould it, test it and sells enough to make a profit?

[Jake]

I'm thinking two bolts, a big washer under each head to be the top and bottom plates, a 1" spacer for both, then a smaller washer and a nut (again, on each). The smaller washer on both the top and bottom stack ups would be submerged. Then a simple round cylinder mold. Insert the top and bottom assemblies, fill it with urethane and let it cure, then pull out a engine mount. I'm trying real hard not to over simplify, but could it really be more complicated than that?

Jake

[UweM3]

I have (as usual) something a little bit complicated in mind.

I would physically limit the travel of upper and lower metal part to avoid them to come apart when the poly stuff may split. i.e. 10-20mm of "poly" travel allowed
and then hit the internal "rebound limiter" to avoid the mount to rip apart.

does this make some sense?

[Jake]

Swap the big and small washers around.

- Bolt
- Small washer
- 1" spacer
- Big washer

Bolt head and small washer submerged, big washer as top and bottom plates, and the extra threads sticking out the bottom and top.

Jake

[booker]

Something like this?

http://www.s14.net/photopost/showphoto.php?photo=9783&cat=500

Mike

[Jake]

That's exactly the intent I'm going for Mike, just done slightly different. I like that way better actually. Who's selling them?





Jake

[The///MadCircle]

I'm guessing these are the pics you've posted:

http://www.hinsonsupercars.com/p-1285-hms-urethane-mounts-c5c6gtorx7.aspx

[UweM3]

That's exactly the intent I'm going for Mike, just done slightly different. I like that way better actually. Who's selling them?





Jake

I bloody give up! Everytime when I think I have a good idea and get stonking rich somebody else has already made it [peace]

[booker]

I'm guessing these are the pics you've posted:

http://www.hinsonsupercars.com/p-128...5c6gtorx7.aspx

That's them. These would likely fit on an E30 as they are just over 72mm in
length and use metric HW. (Stock mount 80mm / 5 Series 65mm).

Mike

[Az in Oz]

I like the look of them. My only concern is that they look like SS and that may not be the ideal material for the threaded section.

[ken garchow]

thanks
another cool option
do you see any problem adding washers to make the 72mm height 80 mm?

still would like to see if the group n have this interlocking feature

[UweM3]

That's them. These would likely fit on an E30 as they are just over 72mm in
length and use metric HW. (Stock mount 80mm / 5 Series 65mm).

Mike

from my trials and measurements I came up with an mount height of 76mm. They sink in a little with weight on them. Could be I had worn mounts though, but I had a few sets to play with.

[ken garchow]

good point do we need to compare compressed heights too, i bet they dont all compress the same amount
how much play would you say there is in height any so as not mess with things such as fan clearance, intake elbow pressure, u joint angle and other items related to motor location?

[conrod]

Hi all,

I have just found this thread and have been reading with much interest, (notwithstanding the fact that my name has popped up a few times!)

There is a whole discussion thread on my mounts here:

http://www.s14.net/forums/showthread.php?t=46247&highlight=gp.a+engine+mounts

so I will try not to repeat any of it here.

Anyway, a couple of points I would like to make regarding the discussion so far.

a) using urethane as an isolating medium. Urethane is quite a useful material to damp out vibration from an engine. It is impervious to oil, will withstand a reasonable degree of heat, is easy to pour into moulds, and can be had in a wide range of hardnesses ("shore" hardness) The big downside is that its adhesive or "peel" strength is rubbish. Poured on to a bolt or washer, and with no other mechanical attachment method other than its own adhesive strength then it will fail, as can bee seen by the number of pics posted in this thread already.

b)

Engine mounts that consist of a compliant material and solid thru-bolt are flawed in design. They are total nonsense. Either the mount is solid, either it is somewhat soft. If it is somewhat soft, then the top and the bottom parts of the mounts should be decoupled.

true, but only to a point. If the bolt is isolated from the aluminium arm that is attached to the engine, via rubber or urethane then it can be made to work successfully. here are a couple of pictures showing how my engine mounts work:





The urethane bush is actually two half bushes, and you may just be able to see from the photos that the bush is tapered, the aluminium arm is machined with exactly the same taper into it, and this locates the whole assembly. The steel spacer tube fits inside the urethane bush so that the bolt can be tightened properly without deforming the urethane bush. The washer under the M10 bolt head is 5mm steel, and it can be seen the even if the whole urethane bush were to somehow disappear, then the mount would "fail safe" meaning the engine would still be captive within the mount. By design the urethane bush is very cheap and replacements are available readily, although I will say that although I have sold many many sets of these engine mounts nobody has asked me for a replacement set of bushes yet! This mounting system is virtually indestructible by design.

The only downside is that they do not come cheap, it was a particularly expensive project to undertake insofar as tooling patterns and machining jigs go, but they are still considerably less than what most vendors are charging for a set of BMW Gp.N mounts.


cheers Conrad