Identifying worn bushes

Technical Area Steering & Suspension
2

Hi all,

Since picking up my 5, it’s developed a knocking from somewhere underneath.  I think it’s at the front end but I can’t be sure, it sometimes does it at low speeds and sometimes in fast corners.  It could be a variety of things, so I’m going to jack it up properly tomorrow and have a thorough check of all the wheel bearings, balljoints, shocks, droplinks and bushes.

I had a quick look at the droplinks last night as I know they could be a likely culprit and are easy to get to with the car on the ground, but I couldn’t figure out how to tell if the bushes are worn or not.  With 115K on the clock, a number of other bushes could also be past their best - is there a way to tell if a bush is worn and needs replacing without stripping down the suspension completely?  A visual inspection perhaps, or seeing how much play the bush has by levering the joint with something?

Any help appreciated - I really want to get this car back in tip-top condition, it’s being used every day and the worry of dodgy suspension is putting up a barrier to my enjoyment of the local twisty roads :wink:

Thanks in advance,

Ax

3

Droplinks are a very likely culprit. I’ve just rebushed all of mine with Polybushes - cheaper than buying new OE droplinks - and progress on bumpy roads is much quieter. The old bushes were in a terrible state, with the inner sleeves torn away from the bonding and the rubber in shreds. A past owner’s drastic lowering of the car, now remedied, can’t have helped.

Provided both wheels of a given axle are either bearing the car’s full weight or are both in the air, so there’s no twist and therefore no load in the anti-roll bar, it should be easy to lever the bar up and down and see/feel for movement in the bushes. They go through horrible contortions and have a hard life. If they’re really bad, you might see the rubber trying to escape from the metal eyes with the wheels on full droop.

Hope that helps.

John

4

Thanks John, that’s really helpful :slight_smile:

I did wiggle the droplinks around yesterday and they seem to twist a lot on their bushes, although I couldn’t tell if there was much play in the bush itself.  I guess a proper look with eyes and torch will be more useful than a blind feel.

The rear rollbar was quite easy to move by hand, it’s not as strong as I thought it would be, so maybe the bushes mounting it to the chassis are shot too.  I’ll get the wheels off and get a torch in there, and a bit of penetrating oil while I’m at it, in advance of potential repairs next weekend!

Thanks again :slight_smile:

5

I wasn’t paying full attention… just realised you have a Mark 2 which has different droplinks with balljoints (a much better design) instead of bushes. So if they’re worn, which you might be able to feel in the joint by levering against the anti-roll bars, the whole droplink needs to be replaced. Apologies for misleading earlier post.

John

6

Thanks again for the help!  I got underneath the car yesterday and had a good long look at everything I could find, but I’m still not sure I’ve really found anything at all, to be honest!

The droplinks don’t look worn and they don’t “knock” while moved by hand.  They swivel smoothly but don’t feel particularly loose.  Given that they’re not an expensive part and dead easy to get to, I might just replace them anyway.

The ARB itself moves if levered, I’m surprised at how soft it is - I couldn’t see any play in the ARB bushes but again I don’t know how easily the bar is supposed to move, and for the cost of the bushes I might just replace them too.

I couldn’t see any problems with any of the wishbone bushes - they all look pretty solid.  The wheel bearings feel fine and the brake pads are properly seated, have plenty of meat left on them and don’t appear to be moving.  However, the callipers themselves do seem to move around quite a lot on the slide pins - most of the cars I’ve owned have been the other way, the slide pins have been very stiff or siezed, so it felt a bit unusual that the calliper moved so easily when I tugged it around.

I looked under the shock boots (which were in great condition themselves) - I can’t see any evidence of a leaving shock, it all looks nice and clean.  There was no play in the shock that I could feel.

However, the shock bottom bushes on both sides are in terrible condition.  The bushes have properly split open and look really ugly.  I couldn’t feel any play in the bushes by tugging on the shock leg, but then again I’m not as heavy as an MX5.

I also had a feel for play in the steering, as yesterday the knock was occuring just when turning the wheel from side to side.  The balljoints are solid and I couldn’t feel any play in the rack, although if I swivelled the hubs from side to side with the wheels off the ground it felt quite light between the change of direction - I don’t know if this is an indication of a worn rack or if it’s just the way the PAS fluid is moving around as I change direction.  The steering wheel was moving smoothly throughout and there was no obvious clunk in the rack.

I’m open to any suggestions.  I’ve already been considering a coilover kit, and if I have to replace the shock bushes I might as well do the coilover conversion, but equally I don’t want to throw money at the shocks when it could be as simple as ARB bushes.  I’m thinking to replace the ARB bushes and droplinks first, on the basis that they’re a common fault, and the shocks will get changed eventually anyway.

Thanks in advance for any further advice that may come my way :slight_smile: