Warning about the use of aftermarket bushes in the front suspension

MartinClan · #1 22nd April 2009, 12:25

After the euphoria of (nearly) passing the SVA I gave the car a once over last night and was a little horrified as to what I found.

On one side, the front nut holding the rod thru' the top wishbone had started to pull through the bush (complete with washer). Closer examination revealed why. The standard M10 washer is not much bigger than the metal sleeve in the bush. The force of doing the lock-up brake test had put sufficient load on the front wishbone arm that it temporarily moved forward (distorted) taking the polythene bush with it drawing the nut into the bush. The problem is that the polythene bushes are an easy fit (unlike the rubber Fiesta ones) and offer little lateral resistance.

As a temporary solution I am going to fit some large machine washers (front and back) which should stop it happening again. As a long term solution I am going back to the Fiesta bushes (assuming I can locate some). I suggest anyone else running these bushes checks them carefully.

Robin

PS - It's not a problem on the lower wishbones because the bushes are gripped on both sides by the mounting brackets.

Patrick · #2 22nd April 2009, 15:43

I've seen larger washer used to avoid this problem, that would be a good solution.

Even the after market shocks on my E46 use a big washer to keep everything together

IIRC They stopped making the fiesta bushes so they might not be so easy to get a hold of.

peterux · #3 22nd April 2009, 20:21

Now that's something useful the SVA man could have spotted instead of worrying about inconsequential semi-sharp edges!

I dug out a picture of a Marlin built car taken at Donnington 2006.

You can just see a washer but it's not very large? I guess you need something the same diameter of the bush? I've used those large 'repair' washers on my exhaust mounting but they seem to be quite soft and deform easily, so maybe a couple of washers each end?

I had intended changing my rubber bushes as they are very soft, leading to an alarming amount of movement when braking.

It's never a dull moment with these cars and you've only done 50 miles!!

P.S. notice the shock absorber mounted the wrong way up.........one side effect of this is that the spring seat adjuster ring is shielded by the top suspension wishbone.

MartinClan · #4 22nd April 2009, 20:46

Quote:

Originally Posted by peterux

Now that's something useful the SVA man could have spotted instead of worrying about inconsequential semi-sharp edges!

I dug out a picture of a Marlin built car taken at Donnington 2006.

You can just see a washer but it's not very large? I guess you need something the same diameter of the bush? I've used those large 'repair' washers on my exhaust mounting but they seem to be quite soft and deform easily, so maybe a couple of washers each end?

I had intended changing my rubber bushes as they are very soft, leading to an alarming amount of movement when braking.

It's never a dull moment with these cars and you've only done 50 miles!!

P.S. notice the shock absorber mounted the wrong way up.........one side effect of this is that the spring seat adjuster ring is shielded by the top suspension wishbone.

Interesting....

So that accounts for why Marlin mount their shox the wrong way up. I think I would rather have mine the right way up and with a cover over the lower plate...

I recon that that car will/would have had the same problem with the bushes. With a washer that size there is nothing to stop the upper arm moving forward the same as mine. What it needs is a thick washer the same diameter as the bush. I can't actually do that....

Why?

Cause one of the failure points was the sharp edge of the bush! They asked me to put a radius on it of 2.5mm! They checked the "stiffness" with some sort of fancy meter and reckoned it must be radiused!!!!!

Robin

peterux · #5 22nd April 2009, 22:50

Best to go back to the rubber ones, then?

Here you go.....
http://cgi.ebay.co.uk/Pair-of-Inner-...1%7C240%3A1318

http://cgi.ebay.co.uk/FORD-FIESTA-MK...1%7C240%3A1318

GreatOldOne · #6 23rd April 2009, 08:01

Quote:

Originally Posted by MartinClan

I recon that that car will/would have had the same problem with the bushes. With a washer that size there is nothing to stop the upper arm moving forward the same as mine. What it needs is a thick washer the same diameter as the bush. I can't actually do that....

Why?

Cause one of the failure points was the sharp edge of the bush! They asked me to put a radius on it of 2.5mm! They checked the "stiffness" with some sort of fancy meter and reckoned it must be radiused!!!!!

How about cutting your own washer, the same diameter as the bush from heavy (thick) plate and then put a radius on that? The bush will be completely behind the radiused 'washer'

Not entirely sure how you'd do it though - A lathe? Bar stock the same diameter as the bush, radius the front and then part it from the bar so it's about 4mm thick?

MartinClan · #7 23rd April 2009, 09:19

Quote:

Originally Posted by GreatOldOne

How about cutting your own washer, the same diameter as the bush from heavy (thick) plate and then put a radius on that? The bush will be completely behind the radiused 'washer'

I'd thought about that. Seemed to be a good idea.

But the problem is that the bar that is threaded at both ends isn't long enough. There has to be at least two turns of the thread protruding through the nylock nut to satisfy the SVA. (They checked ALL mine pulling of every nut cover).

I think I will have to put a radius on the bush as they suggested - and then look for a better solution after.

Keep up the good idea's though guys! As I fix each problem I will post up a picture of before and after.

Robin

Patrick · #8 23rd April 2009, 08:07

How about this:

Use a hole cutter to get the approx size, then put a bolt in the disk you've through the centre hole. Mount this in a drill then use either a file, or maybe even an angle grinder to trim down the piece to the right size and put a radius on it - uses the same principals as you would on a lathe only a bit cruder

peterux · #9 23rd April 2009, 08:54

How about just glueing a couple of these to the front washer?

http://cgi.ebay.co.uk/HARD-RUBBER-FE...1%7C240%3A1318

You will have to drill or ream out the centre to fit over your plastic nut cover. If you bond it to the washer, I don't think they can argue?

It might even look quite nice?

GreatOldOne · #10 23rd April 2009, 10:56

The only other thing I can come up with is a "super size" nut cover - something that covers the nut and the offending edge of the bush. Dunno what would suit though... Google ahoy!

Patrick · #11 23rd April 2009, 11:08

Quote:

Originally Posted by GreatOldOne

The only other thing I can come up with is a "super size" nut cover - something that covers the nut and the offending edge of the bush. Dunno what would suit though... Google ahoy!

If anybody has access to a vac form machine it would be no problem to make something like that.

cabrioman · #12 23rd April 2009, 11:01

I can buy 40mm diameter stainless steel repair washers with an M8 centre hole from my local stainless supplier, would they not be big enough to solve the problem, they are the thickness of a conventional washer, around 1mm.

John