Diff Mounting

[Guest mcramsay]

I was wondering if any one had tried making up or has used flexible mounts for the diff? Rather than using washers/ pre cut spacers to centralize and bolt the diff to the chassis I was thinking of making up some rubber mounts?

 

My idea is to first center the diff using washers, and then measure the lengths each mount would have up be to center the diff, then machine some bushes to this length, I would keep the Internal diameter of these bushes larger than normal and then place and center an inner tube in the bush and then fill with a rubber compound we use which is for manufacturing engine mounts, it's like a liquid rubber which when mixed with a hardening agent it will go off to a solid rubber.

 

This would mean the diff would be fixed securely to the car how ever it will have some dampening and not be bolted fixed to the chassis,

 

My idea is almost like the zero wishbone bush set up.

 

Wouldn't be hard to do, I don't really think its needed but any car will have some kind of dampening/ flexibility for a fixed mechanical conponent bolted to the chassis.

[Longboarder]

Sounds like a nice idea. The rubber will have to be very hard as there is a lot of torque for it to cope with. You do get used to the roar of the various components reverberating round the chassis!

 

Nigel

[richyb66]

I can't see what the benefit would be, the small difference in NVH that it would make would be insignificant compared to the rest of the noise on the car. The only reason car manufacturers use rubber mounts is to reduce NVH and to allow compliant movement between components - as the diff doesn't need to move relative to the chassis why bother?

[Guest mcramsay]

I just think mechanical parts with a bit of force going through them should have a little flexibility, for example the engine and gearbox both mount on rubber bushings.

 

But at the end of the day yes it most likely wont make a blind bit of difference

[fry61]

Go with your rubber mounts, then I'll have some-one on my side. When we built Florin I asked the same questions & told to bolt diff up solid. My reasoning same as your's -- engine & box on rubbers so why bolt rest of power train direct to chassis. All Mr. Fords rubbers were re-used -- cross tube -- trailing arms & rear diff mount without the car behaving like a jelly.

[agent_zed]

i would guess it would be a bit smoother. On my 2b i removed the rear diff rubber mount, bolted the subframe solid and removed the ford prop which had a rubber donut. Whilst i imagine you may lose a bit of response as it must flex before taking up drive, the vibrations must be less.

 

whether its significant or worth the effort only time will tell, but its always fun to find out

[Guest mcramsay]

i dont have my heart set on doing it, i just wanted to see what others thought, i just always found it strange that the engine, and Gbox are mounted on rubber, and then the diff just bolts straight up to the chassis,

 

in the real world, its a kit car, with a 2.0 zetec sat on your lap, with 1mm thick panels, no matter what you do, the thing is going to vibrate and make noise.

 

and to be honest thinking about it, any one that seriously does motorsport will more than likely have solid engine mounts. and a solid Gbox mount. to stop things flexing when you hit the loud pedal. i might have just answered my own question thinking about that one!

 

ive got enough to get on with without making up Diff mounts that i will never ever notice!

[Grim]

it probably would reduce noise, but given the torque on the diff, the size of the bushes you could fit in the gap, and the short distance from prop to bush (amplifies force), i don't think they'd survive very long.