After carelessly wiping one corner of the suspension off on a tyre wall I decided now was the time to replace the bonded rubber bushes in my front suspension with Polyrace polyurethane bushes and bought some from the nice Mr Rallydesign.

They come with the center steel sleeve or crush tube about 13mm longer than the bushes - I presume I have to shorten it to suit.

How much pinch or slack should there be?

The polybushes are have an internal measurement of 1" between shoulders and I have made the steel sleeve they fit into 30 thou oversize so the bush halves will not quite meet in the center. This makes the extermal size of the polybush 1.335" how long should I make the crush tube? 1.32, 1.35" or what?

I don't want too much movement but on the other hand I don't want any stiction. What have you guys done?

David

The bushes supplied by mac, meet in the centre, the crush tube is the length of the bush, not oversize, and all fits snugly into the chassis bracket.

HTH

The crush tube should be the same length as the gap in the chassis brackets.

When the bushes are inserted into the w/b tube up to the shoulders they should be about 0.25mm less than the crush tube.

A blob of grease is added inside the w/b tube before the second bush is pushed in.

The gap between the bushes is now filled with grease and any surplus is pushed out when the crush tube is inserted.

When bolted to the car the crush tube is clamped so it cannot rotate and the bushes are free to rotate on the crush tube
lubricated by the reservoir of grease between the bushes.


Once again, this is just my opinion, and is how I did mine.


Cheers
Paul G

I agree with 907 BUT you need rubber grease rather than normal grease as this will eat the bushes?!

Thanks guys it makes sense

David

quote:

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Originally posted by 907
The crush tube should be the same length as the gap in the chassis brackets.

When the bushes are inserted into the w/b tube up to the shoulders they should be about 0.25mm less than the crush tube.

A blob of grease is added inside the w/b tube before the second bush is pushed in.

The gap between the bushes is now filled with grease and any surplus is pushed out when the crush tube is inserted.

When bolted to the car the crush tube is clamped so it cannot rotate and the bushes are free to rotate on the crush tube
lubricated by the reservoir of grease between the bushes.


Once again, this is just my opinion, and is how I did mine.


Cheers
Paul G

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quote:

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Originally posted by 907
The crush tube should be the same length as the gap in the chassis brackets.

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quote:

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Originally posted by MikeRJ

quote:

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Originally posted by 907
The crush tube should be the same length as the gap in the chassis brackets.

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Unless the brackets are the wide ones on the front upper wishbone to give some camber adjustment, and need to be packed out with washers.

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Hi.

I think there is some confusion here between the std plastic bushes that the manufacturers are using and the proper polyurethane ones that are being talked about here.

With the pollyrace type there is no tolerance on the crush tube. It should be the same lenght as the bush when assembled into it's housing.

Mind if opting for the true polyurethane type bushes the Superflex ones get my vote and they also come in a choice of shore ratings and with a stainless crush tube as std and sachets of the correct grease.

Cheers Matt

quote:

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Originally posted by rusty nuts

Think you mean caster adjustment.

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[quote
Mind if opting for the true polyurethane type bushes the Superflex ones get my vote and they also come in a choice of shore ratings and with a stainless crush tube as std and sachets of the correct grease.

Thanks chaps I emailed the manufacturers and they said ;_ "Crush tubes are just sub flush, to seal out dirt and water."

I see where the manufacturers are coming from but from the performance point of view rather than the longevity I reckon I'll follow you guys advice.

I'll let you know if it goet tits up and I end in the trye wall again

Will check out superpro next time I buy some.

David