Suspension bushes / tubes.
 

Hi folks, I am a bit unsure about the suspension bushes and tubes - the crush tubes are 44mm long, the bush tubes with bushes installed are 44mm long and the suspension brackets have a 44mm spacing. This means that when I do up my bolts some of the bushes are effectively clamped by the suspension brackets and make an awful noise when the wishbones move up and down. Am I right in saying that the crush tube should be kind of clamped by the suspension bracket and the bush then is allowed to rotate around the crush tube? Or do I just not tighten them up so much and the crush tube rotates around the bolt? I hope that makes sense. It just seems a bit strange that the crush tubes are not 1-2mm longer than the combined length of the tubes / bushes.
Thanks in advance,
Enoch.

The bushes need to be slightly smaller than the crush tube. Its worth mentioning that the wishbones should squeak a little when moved and shouldn't move freely when tightened up.

For the bush tubes Enoch you need to dog them right up, the poly bushes will then compress slightly and the brackets will clamp the s/s tubes so that the poly bushes rotate around the s/s tubes. They can squeek but if you use copper slip grease on the s/s tubes this will stop this. Some people recommend silicone grease but at nearly £20 a tube its expensive and i have found copper slip to be better.

There should be no play on the joint and be relatively stiff to move by hand, they will soon wear in.

Regards....AndyH

Tighten them up with the full weight of the car on the arms, not with them in the air.

TT

Thank you very much, gentlemen, that's kind of what I thought. On one of mine the suspension bracket is very tight on the bushes rather than the crush tubes. Thanks Spud for the tip on the copper grease, I have some of that so will use it.
Thanks again to all.

On a related note, what are the tolerable tolerances of the length of the bush tubes? I don't have a lathe, so I cut them with an agry grinder and then file them down for squareness and length. Now I have several tubes that are 0.5 mm too short. Should I bin them or use them?

Bush tubes
 

Hi Albert

Personally I would imagine that .5mm shorter on the bush tube is way better than being, too long ;)

As long as you can bolt the assembly up tightly & have no undue play it should be fine.

If needs must, you can file a fraction of a mm from the crush tube .... The suspension bracket will soon pull in a tad ;)

I know you had great difficulty getting hold of that tube .... I have a few spares that are machined within .01mm if you are desperate for a few :)

Thanks Ronnie, I had to buy the whole 6 m length, so now I have plenty of that tube, and no more questions about what to make the rear rollbar stays from :)

I bought one of the pre-bent roll bars from the first of AshG's group buys :)

For the back stays I used some 27mm OD seamless tube ( 3.25mm ) wall .... For the cross bar I used a section of the wishbone bush tubing !!

To be honest I just used what I had kicking about the place :rolleyes:

Quite happy with the back stay material but not 100% certain about the choice of material for the cross bar :confused: ( Should be strong enough !! )

cross bar needs to be 38mm 3.5mm minimum. if you have got two 100kg people in the car. in an accident at 30mph their weight increases by 12X so that is a potential tug o 2.4tonnes now to be safe you double it. so call it 5tonne rating. 38mm 3.5 cds will take about 8-9tonnes as long as it has captive welded endes which it will do being welded to the main roll hoop. with it setup like that you will rip the chassis to pieces before the roll bar gives.

as for bushes and crush tubes mine were tighter than handy andy to start with. bit o copperslip and a drive about sorted that though.

when they are bolted up to the chassis you should be able to lift the front lower wishbones and they will stay where you lifted them to. but it shouldnt be difficult to move them up and down. also they will squeek a bit until they have been driven on