The-T-Bar MGF Forum

This applies to the MGF only.
Having recently had the rear damper off the car i thought I would investigate why the bottom bush so often quickly deteriorates.

First, I removed the inner metal sleeve and measured the bottom fitting on the damper. You can see it is 20mm across.



You can see that the bush within protrudes about 1-1.5mm each side. I also measured a new bush and that is 22/23mm across.

The inner sleeve however is 26mm long

With the nut/ bolt/ washers and sleeve I was able to 'mock-up' the actual setup on the car.
I think you can see that the bush can move around when the sleeve is clamped between the two washers.



So even if you tighten it up completely, the bush is not compressed and actually has a couple of mm to move about on the sleeve. Initially I think a new bush will feel reasonably secure, but after a short time the bottom fixing of the damper will be able to move around on the inner sleeve. Result - quickly knackered bush.

Those of us who are F owners will know that this is often an MOT fail. Usually the rears are worse but the same problem applies to the fronts.

I have just had to replace the front bottom bushes after hearing a knocking noise on bumps. Investigation showed the bush had deteriorated enough to allow the damper fitting to hit the inner sleeve. Which is one of the reasons I decided to investigate WHY?

It seems strange to me that the inner sleeve should be 6mm longer than the bottom damper fitting.

To me the logical solution is to reduce the length of the sleeve.
So, using a grinder, I reduced it to approx. 22mm. I was careful to clean off any burred metal - we are trying to prevent damage to the bush after all!



I replaced the bush and inserted the shortened sleeve, Then I refitted the damper to the car. The bush is now slightly compressed between the two washers when nut is tightened up. The bottom of the damper is now much more secure.

I admit that until some time has passed I won't know if this solves the bush problem or whether it actually causes other problems, but to make a proper comparison I have modified one front and one rear damper bush sleeve.

Just a quick update.
This modification is showing good results, so far. We've done several thousand miles and there is no play in the bottom bushes and the rubbers look as good as new!

I have also modified the other two bottom bushes now.

edit:- I can also confirm that although Rimmer Bros, B&G etc only list a replacement bush for the rear damper, the same bush also fits the front dampers. MGR o.e. part number NAM9017.

David, Having had an 'advisory' for the o/s rear damper bush on my last MOT I think this is something I may tackle over the winter, is it just a case of taking the wheel off, whilst car on axle stands, and unbolting the damer at the bottom end then fiddling the bush out?

Peter

Swerving;14850 wrote:

Peter, basically yes!

There is an inner steel tube as you see above, it is easier to fit the new bush to the damper/shocker, then using a lubricant push the tube through the bush. You may need to use something like molegrips or even a small vice to force it through and get it into the correct position.

It is well worth carrying out the above procedure, as I had to replace these bushes twice in two years, but since the modification the bush has remained as good as the day it was fitted.

Having just checked these bushes today prior to the MOT, I can confirm that the rubber bushes are still in perfect order! The bottom of the damper/shocker is still held firmly and will pass the inspection with flying colours.

9 months on, and the bushes are still perfect.
I think it's safe to conclude that this is a beneficial modification.

Similar to when I put the 'Ikea cutting board' washers on Megs lower bushes - similar squishing and performance .

Checked these bushes again today. Still looking good! I think we can declare this a RESULT!!

Got an advisory on this on my recent MOT.

does anybody sell the pollys bushes that replace these,

rayb wrote:


There's an eBay seller who produces a cheap kit:



I was emailing them before I went on my cruise / fell ill, but I haven't contacted them since. I was talking to them about bulk buy discounts for the forum. Also trying to ascertain the 'stiffness' of the bushes as they do them in various colours and these do not correspond to stiffness like most manufacturers (i.e. orange is usually a 'comfort' ride, blue is 'sport' etc).