Self made motor mounts?

[flyeyes]

I was thinking about reinforcing motor mounts with a urethane filler. I was just wondering if anyone has done this or what recommendations were on this? I know it has been, and can be done. I'm just not sure on how it's done and where and what type of urethane to purchase.

Anyone else have experience with this type of job?

 

[sophis]

I remember seeing this a while ago. The guy used 3M Windo-Weld Primerless Super Fast Urethane:

http://www.raktron.com/misc/mt.htm

 

[JeffShoots]

Anyone else have experience with this type of job?

Yep, I've seen it done. The problem is not filling the centers with Urethane. Just make 2 tin covers that will hold the centers with a hole to fill.

But how do you plan on getting the old stuff out? Burning it out sucks.

Just get the SOS one's and save your self the trouble and the SOS rubber is replaceable.

 

[Ojas]

The Science of Speed ones look nice, but if you want to make your own, I don't think it's necessary to get the old rubber out - just fill the void (there's a lot of it) with urethane.

From DAL Motorsports: Engine Mounts, by RacerX-21:

<img src="http://www.dalmotorsports.com/images/CarNotes/image026.jpg" align="right" />Engine Mounts- Even the stock HP will eventually tear the OE engine mount. They are a webbed rubber design that won’t handle much abuse. I have seen continuous exhaust cracks due to their flexibility. You can easily make your own polyurethane mounts, by purchasing a two part polyurethane, sealing one side with good duct tape, level them before pouring, and let them dry. The tape will come off easy, and you can trim any overflow with a razorblade. Don’t forget to put something down to protect from runoff. Etching the OE rubber before pouring would be a good idea, but not necessary as the liquid urethane will seep and harden on both sides of the mount.

 

[Elite]

The Science of Speed ones look nice, but if you want to make your own, I don't think it's necessary to get the old rubber out - just fill the void (there's a lot of it) with urethane.

From DAL Motorsports: Engine Mounts, by RacerX-21:

Like Ojas said, just fill the void.

 

[flyeyes]

The urethane casting compound I found that seems reliable was at www.mcmaster.com as item# 8644K18

If you search this item it shows a tensile strength of 3120psi. I would think that this material would work with no issues. Can anyone else lend some more input? I think I'm close to my decision now and being more educated as well.:biggrin:

 

[geometro]

I was in the market for inserts also, but it seems like the only way to do it is the DIY. Energy Suspension or Prothane don't make a kit, unfortunately.

Would love it if somebody with more experience could chime in on which compound to use...

--
George

 

[Ponyboy]

Aluminium. Make those bad boys solid.

My car is at ScienceofSpeed for an engine rebuild and Chris said it was so loud that they thought something was wrong. When the stock engine was in it sounded like a screaming banshee so I can't imagine what it sounds like now. He attributed the sound, partly, to the solid mounts b/c the car seems to be a tuning fork/sounding board for the engine.

Good or bad, the solid mounts won't be breaking anytime soon.

 

[Daedalus]

I would be concerned about matching stiffness and the 1-g location. In other words, where do you want the center bushing to be when you cure the fill such that, when loaded, it ends up in the same place as stock? Strength aside, how will the fill react to the dynamic loads of the engine? The SOS mounts have rubber pieces that appear to be press-fit into place and thus pre-loaded.
Solid mounts will increase stiffness at that joint. Higher stiffness=increased loads. Increased loads=increased stress. The mounts may not break, but something else might, or at least wear out faster.

 

[john@johnhudakracing]

I was thinking about reinforcing motor mounts with a urethane filler. I was just wondering if anyone has done this or what recommendations were on this? I know it has been, and can be done. I'm just not sure on how it's done and where and what type of urethane to purchase.

Anyone else have experience with this type of job?

I use Devcon Flexane from MSC, catalog page number 2575 in their big book. It is a two part poly-urethane mix with a tensile of 2100psi and has been proved adequate for mounts and such.

I would be concerned about matching stiffness and the 1-g location. In other words, where do you want the center bushing to be when you cure the fill such that, when loaded, it ends up in the same place as stock? Strength aside, how will the fill react to the dynamic loads of the engine? The SOS mounts have rubber pieces that appear to be press-fit into place and thus pre-loaded.
Solid mounts will increase stiffness at that joint. Higher stiffness=increased loads. Increased loads=increased stress. The mounts may not break, but something else might, or at least wear out faster.

In my NSX I ended up using solid mounts with good success as the way my manifold is now mounted I don't have finagle room for too much torque on it. Little different than sway or suspension bushings, there is no need to over-engineer here just do what works given your own specific application.

 

[flyeyes]

Thanks for the input John, that is exactly what I was looking for.:smile:

 

[DucatiCraig]

Does anybody have a set of solid mounts they are interested in selling? I would like to try a set, but would like to just swap them out.

How much additonal vibration / noise is there with solid mounts (not urathane)? I used to have a car with solid mounts, and I actually liked it.

Thanks

 

[menappi]

Does anybody have a set of solid mounts they are interested in selling? I would like to try a set, but would like to just swap them out.

How much additonal vibration / noise is there with solid mounts (not urathane)? I used to have a car with solid mounts, and I actually liked it.

Thanks

Burning out old mounts and bushings it quite easy, kind of fun also. Also..sorry but what is a solid mount, compared to a rubber or urethane?

 

[OLDMNSX]

I just used a tube of urethane that would be used to seal a new windshield in place. I cleaned the used mount with some citrus cleaner let it dry and put the tube of urethane in a caulk gun, cut the end and filled the void. Spit on your finger to smooth the outside and let it cure. Really pretty easy.
Brad

 

[DucatiCraig]

Solid mounts are made by welding in a plate that fixes the inner bushing to the outer part of the mount, thereby allowing no flex.

I think this is exactly what Shawn has.


- Craig

 

[MJK]

Whatever happened with this? Anybody like to post their expereinces, a time estimate, DIY or something? This might be my next project.

 

[nsxotic911]

On this topic - what is the real risk of drivetrain damage from one broken engine mount? My tranny mount rubber is broken (not the mount itself) and it's been on my todo list..but I haven't gotten around to it. The other 2 look good. Car has about 85K

I have an SC so that puts more torque on the motor.. thoughts?