New motor mount design (with pics)

[firebat45]

Let's face it, the OEM motor mount design sucks. Sure, it can be reinforced, but it's a bad concept to being with.

Quite a few of the other cars I've worked on use a donut of rubber, surrounded by metal, like this:



What I like about that is that no matter how the force is put into the mount, it is trying to compress the rubber against the metal, not pull it apart. Plus, if the rubber degrades and crumbles out, you have a mechanical locked connection, and the mount will not seperate entirely.

So, I decided to make my own. This first one is a proof of concept for my daily driver, that has a really bad front mount. I'll be making a rear mount for it as well. I'm confident in the design and the strength of the mount, but the only way to know for sure is to test it. If there's something I don't like, I can change the design for the next pair of mounts.

This is what I came up with:


Grade 10.9 bolt for the mount, a front tension strut washer to give the mount a flat surface against the subframe, and some scrap steel I had laying around the shop for the rest. Filled with some Shore 80 flexible urethane (very similar to Flexane, different brand).

Before someone mentions it, I don't care about the paint runs, I painted it to keep it from rusting, not so that it would look good. Runs aren't ideal, but this is just a proof of concept. Next mount will be better.

The other nice thing about this mount is the weight. It weighs nearly 1/3rd of the stock mount! 1.32kg vs 3.46kg, or in other words, 4.7 pounds lighter. Doesn't seem like a lot, but 5 pounds off the car in front of the axle centerline does help. Not to mention the difference the rear mount will make, and then removing the torque struts will have a big weight savings too. Every pound counts.

 

[Racer X]

Subscribed?

 

[NotSoSlowSHO]

Great job.

This is similar to an idea Ive had for years.

Only difference is that I proposed to utilize mounts that are already in production.

Similar to these, made for an EVO

 

[firebat45]

Great job.

This is similar to an idea Ive had for years.

Only difference is that I proposed to utilize mounts that are already in production.

I had thought of that too, but really, modifying something else to work is probably more work than making these. This is the same reason I made my own instead of reinforcing stock. I definitely wasn't looking forward to baking the rubber and scraping it out to repour stock mounts with urethane.

Now that I have the jig, and not including the curing time for the urethane, I could make a mount in an hour or so. A 3lb box of urethane is enough to make 6 mounts, too.

 

[Toolman]

PM me when they are for sale. I will give it a real torture test.

 

[nothingtoseehere]

 

[sperold]

Excellent.
The original mounts look like something a kid made up in a hurry.
I hope it works out.

 

[Off Road SHO]

Excellent design. One thing, and you probably have already thought of it, but make sure you beef up the non threaded side of the mount with collars. I used big nuts that I drilled out to fit the shaft of the new 10mm bolts that I supplied with my mounts. I then "jigged" the plate to the cast iron AC mount to get the holes lined up, and welded the drilled nuts to the plate. This distributes the force of the bolt's rocking to a much larger area of the plate. Works very well. If you already thought of this, never mind.

Tom

 

[rubydist]

I like it - good work!

 

[SuperHO]

do want

 

[hawkeye18]

21 years later, and we're getting more innovation in new parts and part design enhancements than ever before. I love it.

 

[shomethe$$$]

Cool, OP where did you get the mount from? got a part number and how much does it cost? what happened to the center bolt?

I could improve my design but cost is a factor, I put 4 solid rubber mounts on my engine install, basically 4"x4" blocks with a grade 8 1/2" bolts through it, then another 1/2" of rubber to isolate the bolts from the frame, so basically, its a solid mount but it can have lateral movement this is where the design needs to be improved but space is a major concern on my setup, total cost $30 for all the mounts, I used 1/8" and 3/16" steel plate stock. On a side note, I used a grade 5 bolt on the front pass. mount, and it snapped right in half, some odd forces or bad engineering in that particular area, I've seen a lot of SHO's break that mount, think its the one you got pictured.

 

[NotSoSlowSHO]

I had thought of that too, but really, modifying something else to work is probably more work than making these. .

You are not following my idea.

The off the shelf mounts would not be modified.

All you would need are custom brackets to make the off the shelf mounts work.

So you would have a custom bracket on the motor side, that attaches to the mount with nothing more than a bolt.

And the off the shelf mount would bolt to a custom bracket, that would bolt to the subframe.

Easy peasy. :wave:

The idea is to limit the amount of cost involved to fabricate custom mounts.
using off the shelf stuff makes this easy. And eliminates any need for pourable urethane, molds, jigs, etc.

 

[hawkeye18]

You are not following my idea.

The off the shelf mounts would not be modified.

All you would need are custom brackets to make the off the shelf mounts work.

So you would have a custom bracket on the motor side, that attaches to the mount with nothing more than a bolt.

And the off the shelf mount would bolt to a custom bracket, that would bolt to the subframe.

Easy peasy. :wave:

The idea is to limit the amount of cost involved to fabricate custom mounts.
using off the shelf stuff makes this easy. And eliminates any need for pourable urethane, molds, jigs, etc.

And, when the mounts eventually wear out or break, you can go into the store and say "I need a front motor mount for a ______ (insert appropriate car)", instead of having to repour urethane, etc. etc.

Although Advance Auto will wonder why they all of a sudden are selling 300% of the normal amount of Evo front motor mounts!

 

[NotSoSlowSHO]

Bingo.

You have ONE set of custom brackets, and the rest is an easy to obtain, off the shelf, CHEAP mount.

 

[NotSoSlowSHO]

here is another example.

An aftermarket mount for a jeep Wrangler.

http://www.summitracing.com/parts/TRD-4213/




You get TWO for $50

 

[firebat45]

If you already thought of this, never mind.

Hadn't thought of that actually. The stock mount isn't reinforced around the bolt holes so I didn't reinforce them when I made mine. In retrospect, it would be a good idea, I'll probably weld on some thick hardened washers before installing. Thanks!

Cool, OP where did you get the mount from? got a part number and how much does it cost? what happened to the center bolt?

No part number, I poured the urethane myself. No center bolt either, I didn't see the need, as there's a single bolt to take the mount off the subframe about 2 inches lower. This let me use a larger center pipe, to distribute the forces into the urethane better, and less complication than bushings and bolts. I used about $7 worth of urethane to make the mount, and mixed up way too much. Next time I'll only need about $4-$5 worth.

You are not following my idea.

The idea is to limit the amount of cost involved to fabricate custom mounts.
using off the shelf stuff makes this easy. And eliminates any need for pourable urethane, molds, jigs, etc.

No, actually, I followed. My point was that it's more work to build those custom adapters than it is to make my mount. Granted, once you've made the adapters once, you're set, but you still need to buy new mounts. Repouring urethane is much cheaper, just more hassle. It would definitely be a bulkier/heavier solution as well (not trying to say you're wrong, just giving you my reasons for doing it this way).

Besides, I'm not planning on ever having to replace this mount. How often do reinforced SHO mounts go bad?

 

[ycode90]

Good job .

 

[zach44102]

my moter mount is garbage and im fabricating solid mounts for mine but i would be interested in these if you can make me a couple. depending on the price of corse. but looks like a great job

 

[SHOtime2511]

You should think about doing some testing and sell these.