Anyone tried ally diff bushes?

[Sheck]

Hey guys, in an attempt to rid myself of axel tramp i got dad to machine up some alluminium diff bushes. Not a whole replacement bush that sits inside of the diff holes(mounting tabs?) but its on that sits under the mounting tabs themselves and fills the gap between the bottom of the diff and the top of the rubber bits of the thing that bolts to the bottom of the diff (bad explanation).

Basically its a donought of ally and i jacked the car up and held the diff up with the jack, then unbolted the main bolt that hold the diff in place either side. I also took off the two size 12 bolts that hold that mounting tab up. Then put the donought inbetween this tab and the bottom of the diff mounts.

Ok now its bloody awesome with no tramp as of yet and the gear shifts are much more direct. But i have a bit of a vibration at 3.5k rpm. I've already got a few idea on how to fix this but it'll be a bit of trial and error with my last option being to make it out of polyurethane or teflon (teflon will be free/cheap and will be made at my dads work). If anyone has any tips on making it a bit quieter (cant be good for the chassis to be vibrating) but just as effective then let me know. Otherwise i'll post up again once its all done and good for daily driving (or at leats good enough for ppl to put in before and event, drag/circuit, and then remove once done) and see if anyone would want a set.

Cheers
Dave

[Dave]

Hi Dave,

What you have done will certainly cure axle tramp, however it will almost certainly cause issues down the track...
The vibration will be part of it, and I would also expect a short lifespan for the uni-joints on the tailshaft. This could get ugly if left to get bad for a while, as tailshafts failing at speed can get interesting!
I would suggest substituting the \"no-give\" alloy for a stiffer than stock nolathane (can still be turned on a lathe if you can't buy the right size...). It will be much kinder than the rigid alloy on a day to day basis.

[Sheck]

How does it put more strain on the tail shaft? I was trying to think of things it would damage later on and couldnt think of much.

I figured that since the diff isnt moving up and down anymore (there is that 12-14mm space that the diff moves and causes axel tramp) then it should be easier on the drive shafts and tail shaft cause it'll be in the same position all the time.

Cheers for the tips, i'll see how i go with the re-design and see if that cures most of the vibrations first and then yea teflon or polyurethane is the next option.

Dave

[Babalouie]

Those rings are available in Japan, but it was a top and bottom ring to really lock up the movement, the donut goes on the bottom and the c-section one at the top:
http://www.pitinn.co.jp/rs-ohmiyakita/p ... _color.jpg

A possible compromise with some refinement could be stiffer rubber bushes, which I've got...price has gone up though, US$99.
http://corksport.com/store/large/ilys/m ... ounts.html

What Jolt and I have are this as well, which works really well and only transmits a little diff whine since it's rubber bushed to the body (Roadster made his own version that's *solidly* mounted to the body!):
http://www.metromotorsports.com/product ... ProdID=162

[Dave]

Of course you are right Dave - let this be a lesson to all - don't drink and type!