Help Needed - play in the lower rear upright

[bhertzog]

Hoping to tap into the collective wisdom of the forum here.

On my '63 S1 race car, I have discovered that the bolts that mount the rear upright to the outer rear wishbone hve worn the aluminum mounting hole in the upright. See pics. This is causing some play in the entire upright and unwanted and variable toe-in. Have any of you dealt with this before? Any clever fixes without replacing the entire upright? I am thinking of boring and sleeving the hole with a steel sleeve.

Other ideas?

--Ben
1963 Elan S1 vintage racer
Houston, TX

[elans3]

Exactly my thoughts. Would be a good "save".

[512BB]

Before any fix, I would be investigating why that has happened. After all, everybody corners hard in their Elan don't they, but not seen that problem.

Leslie

[bhertzog]

Yeah, that is a good question. I have been racing this car (in anger) since 2012. I have won the SVRA Vintage National Championship for C Production 4 times.....and for good measure I typically beat most of the AP and BP cars too. Needless to say it gets "abused" somewhat. I assumed that it was just a function of hard use (along with stiff springs, hard dampers, rose-joints, etc.), but you do raise a good question. I haven't noticed any other play/issues that might explain it. I am open to ideas.

-Ben

[512BB]

Only thing I can think of Ben, is that the bolt was not tight enough, and had been so for some time. Lord knows how you got it torqued to 35lbs with so much shaved off the head.

If that is the case, and once you correct it. you will go round 2 seconds a lap quicker, as the bushes have not been performing to their optimum on that side.

Leslie

[bhertzog]

Good thought. I would certainly love another 2 seconds per lap. That would be outstanding.

Help me understand what two surfaces are supposed to be the “bearing” (I.e. rotate past each other) when the suspension moves. It has never been clear to me from the design.

Is it the metal sleeve against the ID of the plastic bush? (I.e. the bolt is tightened down and compresses the upright against the bushing sleeve so that the bolt, sleeve and upright move in unison?)

That makes some sense to me except the stock bushes are rubber and metal sleeve and the two seemed to be joined. I have the hard nylon and metal sleeve bushes. The sleeve can rotate inside the bushing.

Inquiring minds want to know.....

-Ben

[661]

Most race cars would use a spherical bearing rather than the original metalastic bearing, or indeed a polyurethane bearing.
I suspect there has been a bit of axial play in the rubber causing angular wear on the upright, but it would still need to rub. I guess that could be caused by there being a gap between the bearings central metal sleeve and the upright. I've had to pack the gap with washers.( b/w the spherical bearing housing and the upright.)

[Bigbaldybloke]

With the standard rubber type bush there are no moving surfaces to rub against each other and wear. All the angular movement should be taken up in the rubber within the bush, and the centre section and bolt should not rotate in the strut. hence the requirement to tighten these bolts with the suspension at normal ride height which is around mid travel, hence the rubber gets twisted an equal amount in each direction as the suspension moves. This all relies on the bolt being tight enough to prevent the bolt and centre steel bush in the rubber bush from turning relative to the strut.
If you drill out and bush the strut all the torque from the rubber suspension bush will be trying to turn your new bush in the strut, so I’d change out the rubber suspension bush for a poly one which turns on its own bush and should not transmit any torque to your new strut bush.

[bhertzog]

That explanation was quite helpful. Thank you. FWIW I am already running hard nylon outer bushes, so I should be ok.

[vstibbard]

On Std alloy uprights and 26R magnesium ones we've counter sunk and fitted hardened washers which the bush centre presses into when tightened, on worn ones I've had the washer machined to the thickness required to return it to std sizing.

Cheap and easy to resolve

[bhertzog]

Yeah, I like that suggestion. Now armed with a better understanding of what was intended by the design....I think he sleeve is unnecessary, and I like the washer/insert approach. Thanks all. --Ben