nick205
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| posted on 18/9/07 at 02:14 PM |
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MK Indy - rear suspension knock/clonk
Ever since I got it on the road there has been a knocking/clinking noise from the rear of my Indy when turning into my road quickly from a heavily
cambered road into a fairly steep side road. I've also noticed it when going quick over a local hump backed bridge and on a couple of larger
undualtions in the road.
At first I thought something was loose and after looking closely I found a crush tube was slightly too long on the outer end of the passenger side
lower rear wishbone. This was allowing the poly bushes to slide back and forth by ~2mm. I sorted this and reasembled the rear end, but the noise was
still there. Closely checked all the other crush tubes, but they seem OK.
I then figured it might be the shocks reaching the limit of their extension when the load was taken off or maybe the damper extending enough to allow
the spring to come loose from it's seat. With the car up on stands and the rear suspension in full droop I couldn't see anything wrong
though. To test this further I raised the rear ride height by ~25mm to see if cured it. Been out again today and it actually seems worse 
Any ideas what the problem is and how to resolve it?
[Edited on 18/9/07 by nick205]
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Hellfire
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| posted on 18/9/07 at 02:22 PM |
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Have you checked whether it does it whilst not driving... i.e. does it make the noise by jumping up and down inside the car. My guess is that it is
the dampers bottoming out, even though you think it isn't. By raising the rear ride height making it worse indicates the problems lies here,
lower it again and re-try.
Steve
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02GF74
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| posted on 18/9/07 at 02:25 PM |
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do yoiu have a live axle? if yes, check the rose joints for the panhard rod; if they are loose in the brackets, they will clonk.
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nick205
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| posted on 18/9/07 at 02:56 PM |
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quote:
Originally posted by Hellfire
Have you checked whether it does it whilst not driving... i.e. does it make the noise by jumping up and down inside the car. My guess is that it is
the dampers bottoming out, even though you think it isn't. By raising the rear ride height making it worse indicates the problems lies here,
lower it again and re-try.
Steve
Steve,
I have tried lots of jumping around in/on the car with it stationary and it does make noises, but it's difficult to tell if it's the
same.
Also it seems to happen (on the road) when the rear or one side of the rear becomes unweighted. e.g. going over the hump backed bridge. This mad me
think it might be the shocks topping out (?) rather than bottoming out.
I will try winding the ride height right back down and see what effect it has on the road though.
Cheers
Nick
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nick205
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| posted on 18/9/07 at 02:56 PM |
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quote:
Originally posted by 02GF74
do yoiu have a live axle? if yes, check the rose joints for the panhard rod; if they are loose in the brackets, they will clonk.
The Indy is a double wishbone IRS setup.
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MikeR
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| posted on 18/9/07 at 03:15 PM |
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what state are the bushes in the shocks in?
by topping out do you mean the spring outside the shock being fully extended so its not doing anything?
have you checked the wheel / drive shaft are fully tightened to their respective mounts?
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nick205
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| posted on 18/9/07 at 03:31 PM |
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quote:
Originally posted by MikeR
what state are the bushes in the shocks in?
by topping out do you mean the spring outside the shock being fully extended so its not doing anything?
have you checked the wheel / drive shaft are fully tightened to their respective mounts?
Not sure what state the bushes are physically in, but they've only covered 1800 road miles from brand new (Pro Tech shocks). Another thing
worth checking though.
Topping out - yes, so the spring effectively is loose between upper and lower spring seats.
Checked all nuts/bolts and mountings and nothing apparently loose.
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Hellfire
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| posted on 18/9/07 at 04:09 PM |
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Sorry Nick - I meant topping out - <KN0B>...
In our's we set the ride height so that there an equal amount of movement when laden. This means that there is effectively 25mm of travel. When
unladen, a small/medium shock will top the dampers out.
Ideally there ought to be a little more travel as; although it's obviously never driven unmanned, it shouldn't top out when unladen.
All IMHO - Steve
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ReMan
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| posted on 18/9/07 at 07:20 PM |
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Mine tops out occasionally too.
I was diagnosing exactly the same noise and have come to that conclusion,I'm happy with my ride height tho so dont want to sdjusst it, but I
might give the dampers a couple of extra clicks to see if that helps.
Check also, if you have an LSD that gives a smaller clonk sometimes when I turn tightly, especially pushing backwards out of the garage.
And, the top hub carrier camber adjuster nuts, he really big ones. Can be difficult to tighten fully allowing a slight movement.
HTH
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nick205
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| posted on 18/9/07 at 07:28 PM |
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quote:
Originally posted by ReMan
Mine tops out occasionally too.
I was diagnosing exactly the same noise and have come to that conclusion,I'm happy with my ride height tho so dont want to sdjusst it, but I
might give the dampers a couple of extra clicks to see if that helps.
Check also, if you have an LSD that gives a smaller clonk sometimes when I turn tightly, especially pushing backwards out of the garage.
And, the top hub carrier camber adjuster nuts, he really big ones. Can be difficult to tighten fully allowing a slight movement.
HTH
Checked the camber adjustment nuts - no movement there I can see. Also got an open diff which whines a bit, but doesn't clonk.
Interesting to know you have the same issue and have worked along the same thought process though!
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ReMan
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| posted on 18/9/07 at 07:33 PM |
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I can grab the roll bar drivers side and push the car upwards and get the clunk. Not easily, it takes a couple of bounces, but definatly it, try
it.
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