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Author: Subject: suspension bush movement
aka Keith

posted on 30/3/15 at 08:26 AM Reply With Quote
suspension bush movement

Was giving the car a good spanner check at the weekend and have noticed that the top front bush of the suspension wishbone has a little play front to back

The crush tube is tight against the bracket but the bush has about 1mm of movement front to back.

the bushes are a couple of years old, so I not sure if it is ware and tear, or can I put a nylon washer between bush and bracket like caterham do, to take up the slack?


Yours
Craig

PS Anyone know what the OD of the crush tube is - car is MK indy.

[Edited on 30/3/15 by aka Keith]

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Doctor Derek Doctors

posted on 30/3/15 at 12:04 PM Reply With Quote
I belive the crush tube OD is 19.05mm (3/4" )

I would expect the bushes to be slightly wider than the crush tube so that they cant shunt back and fourth. I think my fist action would be to start with some new high quality bushes.

[Edited on 30/3/15 by Doctor Derek Doctors]





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DIY Si

posted on 30/3/15 at 01:34 PM Reply With Quote
If I've understood it right, it sounds like your crush tube is a tad long. If you were to take it out and shorten it, or add the washer, the play would be reduced to a reasonable amount, as there should be a little bit to stop it binding.





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aka Keith

posted on 30/3/15 at 01:57 PM Reply With Quote
the crush tube itself fits snuggly into the bracket on the chasis, which when tightened up, allows the bush to then rotate around the crush tube, but at the moment the bushes themselves allow the front of the top wishbone to move backwards and forwards.

If you where to grab the top front wishbone, you can move it front and backwards (along the length of the car) by a mm or two, even thought the crush tube is tight up against the chassis bracket. Does that help explain what I am trying to say?

Cheers
Craig

[Edited on 30/3/15 by aka Keith]

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Slimy38

posted on 30/3/15 at 03:25 PM Reply With Quote
I see that as being the fine balance between being too loose and allowing the suspension to move back and forth, and being too tight and causing things to bind! Personally I wouldn't alter the crush tube, if you come to replace the bushes you'll then have them too tight.

When I put mine together I am going to use teflon washers both to take up the slack but also allow a smooth surface for the bushes to slide against the bracket.

You could also consider what effect that fore and aft movement is having on the suspension geometry. For example, if it's the rear suspension then does it actually matter that it can move?

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leon51274

posted on 30/3/15 at 03:45 PM Reply With Quote
I might be barking up the wrong tree here but could it be that the bolt is the wrong size ie 12mm and not 1/2"
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joneh

posted on 30/3/15 at 05:56 PM Reply With Quote
quote:
Originally posted by leon51274
I might be barking up the wrong tree here but could it be that the bolt is the wrong size ie 12mm and not 1/2"


That's the same issue I had with my Fury. Had to ream the chassis to 1/2 inch for the bigger bolts to match the crush tubes in the bushes.

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avagolen

posted on 30/3/15 at 08:05 PM Reply With Quote
If I read you correctly, and the bush movement is just along the length of the crush tube,
you will be ok packing it to prevent it floating in that axis as long as you do not cause it to bind.

If the bush is loose on the crush tube, then the bush needs replacing.

I would not shorten the crush tube if it sits nicely in the chassis bracket and is nice and tight.

Doing so in my opinion will deform the chassis brackets from what sounds like a good fit.

HTH

Len.





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aka Keith

posted on 31/3/15 at 12:28 PM Reply With Quote
Thanks all for the replies. Have ordered some nylon suspension washers from Caterham and will see how it goes. Will double check all the measurements and fittings and update if there is any development.
cheers
Craig

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Slimy38

posted on 31/3/15 at 12:58 PM Reply With Quote
quote:
Originally posted by aka Keith
Thanks all for the replies. Have ordered some nylon suspension washers from Caterham and will see how it goes. Will double check all the measurements and fittings and update if there is any development.
cheers
Craig


How much did you pay for them? I was going to get a sheet of material and get it cut, but if they do the proper things for a good price then I might take the easy option.

I assume the ID of the washers is larger than the crush tube, IE it only packs out the bush and not the whole bracket?

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aka Keith

posted on 31/3/15 at 01:06 PM Reply With Quote
The washers are 98p each direct from Caterham plus postage. I am sure you can get them cheaper elsewhere and I will look for an alternate supplier.

The washers are actually 17.5mm ID and 32mm OD so the ID is slightly to small and will need reamed or enlarged to fit over the crush tube so that, as you say, it only packs out the bush.

cheers
Craig

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40inches

posted on 31/3/15 at 01:08 PM Reply With Quote
quote:
Originally posted by aka Keith
Thanks all for the replies. Have ordered some nylon suspension washers from Caterham and will see how it goes. Will double check all the measurements and fittings and update if there is any development.
cheers
Craig


These? http://www.caterhamparts.co.uk/product.php?id_product=1438

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aka Keith

posted on 31/3/15 at 01:22 PM Reply With Quote
Yip, that's the ones.

cheers
Craig

[Edited on 31/3/15 by aka Keith]

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