Shocker bolt

[fatbaldingoldgit]

I am replacing the standard suspension on my LE500 with the VHS Comfort Pack Bilsteins.

The Chinese TFs have different bottom mounting bolts - this is irrelevant to the issue I'm bringing up but are shown here as a matter of interest.

The hole in the bottom damper bush is 13mm ID. This is the same as the standard Chinese and all the MGR TF dampers.

The OD of the above bolts and all the MGR damper bolts is a fraction under 12mm.

There is a >0.5mm clearance all round the mounting bolt.

Does anyone other than me think this is strange? I've spoken to the MGOC (i.e. Roger Parker) and confirmed with Andy Kitson that the bolts and holes are as designed but no-one can tell me why the clearance needs to be so big. The generic answer is "It was designed that way" - therefore it is de-facto needed.

I don't think so!

Anyway, I have had some sleeves machined to take up the clearance. There is still a nominal clearance between the mounting bush and the sleeve but not as much as 0.5mm.

The sleeves are all slightly smaller in length than the bush despite the shot appearing to show otherwise.

Anyone have a view as to why I should not do this?

[Tipper]

The plot thickens!

I bought 4 of those bolts as an upgrade for my 160 Sprint rebuild only nobody said front and back are different! I had assumed all four were the same as they are the same on the original bolts. I have no idea which I have now.

Anyway not yet attempted to fit anything together so no problem, but, I did check the fit into my Bilsteins and some original dampers and noted the different bolt size gives what is best termed a rattling good fit!

I emailed B&G, who supplied them, about it but they couldn't answer my query so I gave up having more pressing things to deal with. I came across the bolts yesterday as I was tidying up my bench and reminded myself to think about what to too. My intention is to seek out some thin walled ss tubing from somewhere and use it as you suggest because a rattling good fit in that area where bolts are known to snap due to fatigue from flexing doesn't seem a good idea to me. The inner retired engineer in me says do it properly!!

Your solution seems right but I can't see why The designers thought it OK with such a bad fit. Does the damper bush still fit into the arm recess with these studs?

[fatbaldingoldgit]

At last!..someone else who thinks this rattling good fit isn't good in any way, shape or form.

Yes, the damper bush does fit inside the top arm..and I suspect that is the reason why the unnecessarily large clearance doesn't cause an issue. Otherwise torque relaxation would cause the bolt to snap pretty quickly. I can't understand why at least the aftermarket damper kits don't specify a bush ID of 12mm to match the bolts..easy enough to do on a kit that is bespoke to an F/TF after all even if the original design was wrong. After market VHS Bilsteins are supposed to provide an overall improvement. Why not improve the bottom bush clearance too?

I did toy with using some 5/16" mild steel 1.22mm wall tubing and having the outside turned down to 13mm..That''s the closest I could get to having some clearance on the bolt but being an interference fit on the bush but my ex- engineer neighbour is a dab hand with his lathe and he knocked me up a set from MS stock one day when he was bored.

[Tipper]

It's strange that the original damper/bolt fit is so slack too! What were MGR thinking and I'm surprised the Chinese didn't pick it up too.

[fatbaldingoldgit]

Because it is so obviously wrong I think I must have missed some subtle reason for it....maybe not..

[Debs]

I had a couple of suspension bolt failures as a direct result of this shoddy bloody design! Both on the nearside rear, both showing classic signs of high cycle fatigue.

I now run Pro-Tech dampers that were bespoke manufactured. These have a shouldered bush that presses into either side of the rose joint and gives a 'sliding interference fit' on the bolt.


Having said that, I am looking to have new top links made that support the bolt at both ends, only a bloody eejit puts a suspension bolt into single shear!

[fatbaldingoldgit]

I've used Pro-tech in the past...great kit...would have used them this time but wanted a fit and forget solution..some hope!

[tickford]

I have just tried to undertake the same task of fitting Bilsteins to my LE500.
I just cannot get the original front damper/spring assembly off of the lower bolt as the bolt is too long to allow the damper to slide off before it hits the body work. Nor will the suspension lower enough to release the top damper bolt from the body work. Nor can I get the lower bolt out of its housing-I assume it is corroded in.
I may be able to release the corrosion but it looks as if the bolt on the left side of seating shoulder is too long to knock through before the damper again hits the body work.
Did you have a similar problem?

[mgtfnut]

Back in 2009 I had a TF damper lower bolt snap when replacing OEM dampers with VHS. Replaced all bolts with new, and been fine ever since.

My take is that clearance of the clamping bolt within the bottom damper bush is sort of irrelevant. The shear up and down forces are taken by the fit of the "spherical" bearing shoulder in the recess of the suspension arm, and the bolt only clamps these two bits together. The bolt takes no part in up and down movement at all, and the clearance is probably to safeguard against any "bending" of the bolt. The fit of the bush shoulder and the recess in the suspension arm is crucial, as any likelyhood of dirt contamination, burrs etc will not cause the bolt to clamp hard enough - and we know what happens then. The correct tightening torque is vital.

Yes, it would have been better to support the damper bush on both side in theory, but production economics and extensive road testing would have shown all to be perfectly adequate for normal road use. The LE 500 had a slightly better arrangement with a drilled suspension arm and a shouldered stud with a nut clamping it.

Just my 2p's worth

[tickford]

Some progress-I have managed to get the old front shocks off with the lower bolts in place. To get the new shocks on I have to get these bolts out and they are stuck fast. They are the later LE 500 dog bolts. There are flats on the shaft which suggests the bolts are screwed into the arm, but they may just have been there to allow the nuts to tighten. Is the bolt screwed in to the arm? Certainly whacking it on the end with a club hammer does not shift it. I have new bolts to fit, so not concerned about damage to the old bolts so long as I can get them out!
Any ideas welcome.

[mgtfnut]

I don't have a LE 500, but look at the pics earlier in this thread, and look at your new bolts. From looking at the pics, it looks like the bolts just slide into the suspension arm, and the flats are there to enable the nut at the end to be tightened.
Only looking at your new bolts will you be able to determine if they are just pushed in - are there any screw threads on the bit that goes through the suspension arm?
I can't understand if you got the bottom shock joint off the stud, why you can't get the new ones on!

Good luck.

[tickford]

Thanks for this.
The thread on the bolt that goes through the arm and that holds the nut is longer than appears after it has been passed through, that is, it is possible that the bush in the arm is threaded, although it seems unlikely as the whole thread would need to be threaded through.
I got the old shock off by forcing it off, with the bush on the foot at an extreme angle. I cannot get the bush on the new shock at that angle as I have nothing to give it that purchase.
Somehow, I have to get the old bolts out.

[tickford]

Success.
Used a large socket over the bolt with a thick washer and bolt nut to draw the bolt outs, using a breaker arm. As suspected, it does not thread into the arm as the original ones did.
Now to get the shocks on! Not as simple as original style as the bolt has to be on the shock and passed into the arm with the upper end of the shock in position.

[mgtfnut]

Success.
Used a large socket over the bolt with a thick washer and bolt nut to draw the bolt outs, using a breaker arm. As suspected, it does not thread into the arm as the original ones did.
Now to get the shocks on! Not as simple as original style as the bolt has to be on the shock and passed into the arm with the upper end of the shock in position.

Result !

Looking at the pics at the top of the thread, it was pretty certain that the shouldered bolt only slid into the top suspension arm.

Are you sure the lower wishbone is at full droop, so that you can swing the top out and make life a little easier fitting the bottom?

[Tipper]

Well done, but having done this are you sure the shocker bottom bush is adequately located into the lower arm recess given that the flange on the dog bolt may now be taking up more/all the space?
It's the lower bush that takes all the suspension loading, not the bolt, although the new dog bolts do look a lot more 'man for the job'!