Stiffening motor mounts for racing application?

[Jetmugg]

As you may or may not be aware, I have a VW IDI turbodiesel 1.5L engine installed in a Dodge Rampage, which I will be using for some land speed racing attempts this summer.

One thing I'd like to do is firm up the motor mounts / transmission mount to reduce the amount of movement in the engine compartment.

The mount on the pulley end of the engine (front of engine, passenger's side of vehicle) is one of the typical VW Rabbit type mounts.  I have heard of people using hockey pucks in this location, but I haven't yet checked the fit of an official black rubber hockey puck.

In the front of the vehicle, I'm using a Dodge Omni mount, that would have been the same mount as used for a Dodge Omni / VW 1.7 gasser combination.  On the transmission end, I have another Omni mount, which was used to mount a VW 020 4-speed in an Omni.

The Omni mounts are rubber "suspension" type mounts.  I'm thinking of filling them with a pourable urethane material to stiffen up the open spaces in the rubber.

I don't think that solid metal mounts are needed (or tolerable), but something more than factory rubber mounts would be nice.

Advice is appreciated.

Steve.

[Gizmoman]

Your idea of urethane filling up the spaces is a good one if you can get it super clean in all the nooks and crannies - although perfect adhesion may not matter. Wonder if you could even use non-hardening silicone gasket sealer?

I have a small shock absorber on my Vanagon AAZ which was there when I bought it. Not sure if it does much but I suspect it may.

[TimpanogosSlim]

i've heard of people filling the gaps with silicone. I think you'd just need to get the surfaces reasonably clean, maybe start by brushing directly onto the rubber, then pour.

[Jetmugg]

We use a pourable urethane compound at work for molding a few different industrial things.  I'll check the durometer of that stuff.  I think I'll probably buy new motor mounts, then fill them with the urethane.

Steve.

[theman53]

I have a very excellent working knowledge of Por-a-cast and many other rigid urethane as I was a plant manager at a place that used these all the time. I also worked for several local weekend warrior racing crews, so I have a little knowledge on both aspects of your dilemma. What we found in the racing shop was that until you went solid all gains were mild. If you made the rubber basically solid there was still engine rock that you wanted to avoid, and almost all the vibration from a solid steel mount. That said circle track is a ton different than top speed racing as you will not be varying your rpms like they do. With that in mind you shouldn't need as much stiffening as they do, so it will probably work very well.

Also, my drag race buddy with a mk1 rabbit that does 12.19 in the 1/4 mile does the prothane engine mounts. Prothane is just a name brand of a poly urethane company that makes stuff for our cars. He breaks the steel portion of the mounts sometimes. So watch how hard you launch
this is the one on the passenger side, I think
http://www.ebay.com/itm/Prothane-22-501-Polyurethane-Engine-Mount-Kit-Front-Red-/380881844124?pt=Motors_Car_Truck_Parts_Accessories&hash=item58ae53b79c&vxp=mtr

[Jetmugg]

I was checking out the Prothane parts, but couldn't quite figure out their designations.  To me, the P/N 22505 looks like the correct part for the passenger's side, but it's listed as "left" side.

http://www.prothanesuspensionparts.com/proddetail.asp?prod=22505

The 22505 seems to just "jam" into the passenger's side motor mount, effectively filling in the gaps.

Thanks for the input.  My "launch" won't be too violent, I'm sure.

[theman53]

Yeah the inserts help, but if they have a solid one go that route. The inserts stiffen for a little while, then rip the stock rubber apart.

[mystery3]

What does the omni transmission mount look like?

I used prothane mounts all around when I installed my 1.6na, It wasn't too bad when moving, increased nvh sure but tolerable-when moving-at idle the poly transmission mount on a caddy application creates too much nvh. I kept the other three but swapped the trans mount for the "heavy duty" oem unit.

I've filled mounts on other cars with the pourable urethane with very good results, as stated it needs to be really clean to adhere properly.

The transmission mount on my old neon was a shock absorber type which I replaced with what amounted to a threaded rod with a lock nut which screwed inside a larger diameter threaded rod allowing you to preload the mount to varying degrees. It was great, a massive improvement in launching and overall feel of the shifting.

[745 turbogreasel]

Try preloading the  top of the motor with ratchet straps.
Doubling the front mount is probably easy fab as well.