Engine and Tranny Mounts

[tim.gelling@eur]

I have searched the Forum's and have read a bit about replacing the engine and tranny mounts, I am looking for more assurance and tips before I begin, any help is greatly appreciated. I am installing sport mounts on an 81 targa.

What I have learned so far;
- spray PB Blaster (from the bottom, engine mounts) soak a few times before doing the job
- use anti-seize when re-installing
- take care not to twist engine cross-bar ends off
- relatively easy, 2-3 hour job
- install one side at a time (question: beyond cracking everything loose can I replace the mounts without loosening each side for clearance?)
- keep everything loose until all bolts are started in on re-install
- support tranny with jack
- order Rennline cross member before you begin

anything else??

also seems to be a debate about how much effect this will have on improving the shifting, any more ideas, experience? I had a RennShift installed with new bushings and a Stomski coupler and a new clutch cable. The shifting improved tremendously but is still sticky at times (into 1st at a stop, 1-2 and rev), my theory is the soft motor and tranny mounts are inconsistent with twisting etc and this is causing it. Also, when I accelerate the shift handle moves back about and inch+ and forward again when I lift so there is significant play there that I am hoping to eliminate and get smoother consistent shifting as well.

thanks tim

[ljowdy]

I have a relatively stock 1973.5 911. I replaced the shifter with a Factory short shifter, then replaced the bushings in the linkage and still, the shifter would flop around on rough roads and going over RR tracks. Shifting was vague at best even with the new bushings. My next step was to replace the transaxle and engine mounts with new stock units.

What a difference. Shifting once again became a pleasure, and the car felt very solid. Sorry I didn't do this sooner and it was cheap, maybe a hundred or so bucks but felt like a million when the work was finished.

I supported the engine with a jack and a 4" x 4" block of wood while I replaced the rear mounts. The hardest part was wiggling around the AC compressor. After the rear mounts were secured, I then moved the jack to the transaxle and supported it while I removed those mounts, again, no problems encountered.

The whole procedure took m only about 45 minutes and none of my bolts were stuck. Came apart easy and went together easy.

Finally, the old mounts were absolute rubbish (hard & dried out rubber) and went immediately into the trash can.

[RWebb]

loosen both sides before removing one mount

the Rennline does not bend (apparently) - the bend allows easier alignment of the bar with the body mounts

- after completion drive a few hundred miles - then loosen & move motor to a equilibrium spot (so it "rests easy") then re-tighten

re-torque after a few hundred more

[azasadny]

I replaced my rear motor mounts a few years ago and "while I was in there", I replaced the sound pad, rear Bilstein shocks, all fuel and vacuum hoses and anything else I could reach and see that should be replaced or cleaned up. Use a breaker bar to get the motor mount bolts loose after using PBBlaster and be careful that you don't snap or bend anything. Good luck, it's not a hard project...

[Grady Clay]

Tim,

Randy (Pelican RWebb) makes a good point about stress relieving the engine-transmission assembly.

I prefer to use the rigid transmission mounts and the stock soft mounts at the engine. The reason is a 911 engine & transmission cannon be a ‘stressed member’ in the chassis. It needs to be torsionally independent of chassis flex. I think this is particularly important with mag case engines and transmissions.

Given the choice, I would design a 3-point mounting with a single spherical bearing at the front of the transmission and slightly flexible mounts at the engine cross mount. A 3-point mount won’t torque the engine-transmission assembly. A 914-6 is mounted like this.

Best,
Grady

[myrddin]

I know this is a dumb question but... If I were to replace my mounts what are the best ones to go with... I to want to improve my shifting.... Any advice would be welcome... I want to keep that factory feel and not introduce noise and vibration... I drive this car every day. I did read something about club sport mounts????

[RWebb]

In order of softest first:
1. stock
2. Club Sports
3. Wevo
4. solid metal

The latter can shake the PMO carbs so badly they malfunction.

Softer means you keep that factory feel and have less noise and vibration. Stiffer means the power train moves less under G forces and shifting will be more precise at those times. You can choose where on the spectrum you want to be by choosing one of the top 3 pics and by mixing & matching Front vs. Rear mounts. You cannot escape the trade-offs involved.

Have you carefully gone thru the shift linkage and replaced every bushing and then fine tuned the shifter as per Sherwood's instructions? The shift tower from any '86 will give you one add'l adjustment also. Or buy the Wevo shifter.

Other options include a complete tranny rebuild or changing to a G-50 trans. (or car with one) since that has the Borg-Warner synchros instead of the Porsche type.

Just add money...

[myrddin]

I have had the transmission rebuilt, they said they replaced the shift coupler (not sure but it loOKs new) the ball cup and shift tube bushing are old I think... I have tried to do the shifting adjustment (shifter in neutral hold left coupler rotate right).

It does shift nice (real nice) when it goes into gear but 3rd and 4th will fight me at times... however if I don't force it and try 2-3 times it will go in as smooth as butter.... But when it rejects the shift if you force it its like pressing against rubber....

If I were to replace all bushings to stock and replace the trans/motor mounts... what would you recommend for a nice feel... I do drive it every day but want any upgrade I can get.... Also should I be OK with the stock shift coupler or do I need the wevo?

I don't plan on a wevo shifter right now, but may try a short shifter??
I will replace the shifter bushings (even the shift coupler to be sure - but its new)
may swap the coupler for a wevo (If needed)
I bet the mounts will help cause they loOK ruff....

Mike