engine and gearbox mounting question

[Malcolm]

I wish to stiffen up how my engine and gear box are mounted in the car. My current mounts are the standard ones for both box and engine ie rubber! Actually soft jelly might be more accurate!

The problem I get is that suffered by many with solid link gearchange systems in that at high rpm shifting the gear gate pattern is not where it was when you checked it at tick over or with the engine off. The torque of the engine moves it about as one end of the gear shift system is chassis mounted and the other on the gear box itself.

My concern with the Renault UN1 transaxle and a Ford 302 combination is that if I solidly mount them in the chassis it will solve the gear shift problem but eventually crack either the block or gearbox casing.

I could easily keep the rubber mounts (put new stiffer ones in perhaps) and then use heim jointed (rose jointed) links in to connect both gearbox and engine to the chassis. Like guy ropes on a tent?

The question I guess is how far can you go in moving towards a solidly mounted engine and box package before you get issues? Any ideas?

 

[Jim Cowden]

urethane
I used an MGB suspension bush in all mounts.

 

[Malcolm]

Thats a neat solution. If I remember rightly cast ali has about 2% elasticity so a polyurethane bush must extend that a bit but won't allow much of the wavering about in the breeze kind of movement I currently get. Most interesting. Pictures helped a lot, thanks for those.

 

[Clayton]

Yep, used urethane as well. Not running yet so cant comment on that.
One word of caution though, I used a solid engine stay on my Escort race car. It made the gear changes easier but went slower. Took the stay off and the speed came back. Can only put it down to the fuel boiling in the webers due to the vibration.

 

[Malcolm]

Have a holley not webbers and the fuel boils anyway (well it did on Saturday!) so can't really make my issues on that score much worse !

Hopefully someone will have driven on poly bushes and can post their thoughts....

 

[Scott Calabro]

Malcom,

Do what GM did in the sixties.

Fab a piece of cable with loops on both ends.

Attach one end to one of the cyl. heads.

Attach the other to the frame.

The cable should just have a slight amount of slack in it.

When the engine tries to rotate in its mounts under a load the cable will tighten, preventing the unwanted issue you encounter.

A 15 minute fix, and best of all you don't have to change the eng/axle mounts.

Go here to see what you will need to fab a proper cable.

Nicopress® from The National Telephone Supply Co.

Cheers,

Scott

 

[MReid]

I have poly engine mounts and alloy tranny mounts and they work fine, although I only have a few miles on my car. Here are the ones I am using for Summit:

Prothane Motion Control 6-503-BL - Prothane Motor Mounts - summitracing.com

Instead of the cable, you could also use this torque link from Competition Engineering:

Competition Engineering C4010 - Competition Engineering Torque Link Kits - summitracing.com