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Front suspension pivoting (again)
sammy - 15/4/07 at 08:52 PM

Having read about the differences between poly bush and rubber bush suspension, and taking into account that nearly all my driving will be on the road and not on the track, I decided to go with the old rubber bushes as per the book.

I know this has been covered before for poly bushes, but not sure which way it is for rubber bushes.

Should the bush pivot around the bolt, or should the wishbone eye pivot about the rubber bush? In the book, the bush and the wishbone eye are the same width but smaller than the space between the suspension bracket, which would imply that the bush pivots on the bolt (i.e. you don't tighten the bolt so much that it pinches the suspension bush/wishbone eye).

Is that right or does the wishbone eye pivot about the bush (so the wishbone eye needs to be made slightly narrower than the bush)?

Thanks!


nitram38 - 15/4/07 at 08:58 PM

The centre sleeve should be gripped tight by the wishbone mount so that it is the rubber flexing between the inner and outer parts of the bush.
If that makes sense?


JoelP - 15/4/07 at 08:58 PM

with bushes i believe that the rubber is bonded onto the bush, and movement is via the rubber deforming - hence leave it loose til you are settled at ride height, then nip the crush tube tight. Thats my understanding of it anyway.


mark chandler - 15/4/07 at 09:01 PM

Crush tube is solid with rubber bushes.

You need to fit loose, set the car to the correct hieght then nip up tight.

failing to do this will result in a short life for the rubber.

Regards Mark


sammy - 15/4/07 at 09:08 PM

Thanks for that! So if it is the rubber deforming that allows the movement, then the wishbone eye needs to be slightly narrower than the bush. Also, no grease is necessary?

Cheers


t.j. - 16/4/07 at 05:50 AM

quote:
Originally posted by sammy
Thanks for that! So if it is the rubber deforming that allows the movement, then the wishbone eye needs to be slightly narrower than the bush. Also, no grease is necessary?

Cheers


Yep,

The grease on the bolt is to prevent rust.
If you grease them it's harder to tight and prevent movement between the bush/bracket.


C10CoryM - 16/4/07 at 03:44 PM

No grease on the rubber at all. Rubber does not like petroleum products and will rot. Also as mentioned before you want the rubber to deflect, not rotate so even a silicone based lube is bad.
Generally there is an inner and outer sleeve that are bonded to the rubber. The outer sleeve presses into the ctrl arm and the inner gets bolted to the chassis. If its one bolt through the middle the chassis bracket must tighten up to the inner sleeve w/o touching anywhere else.
Cheers.


britishtrident - 17/4/07 at 02:49 PM

quote:
Originally posted by sammy
Thanks for that! So if it is the rubber deforming that allows the movement, then the wishbone eye needs to be slightly narrower than the bush. Also, no grease is necessary?

Cheers


In a word no -- if the rubber bush is the Triumph type with no metal outer sleeve the rubber is a pretty tight interference fit in the wishbone tube.

All the angular movement is accomodated by torsional strain within the rubber.