Lotus Elan

Polyurethane Bushes

PostPost by: miked » Fri Dec 10, 2004 1:08 pm

I have read the comment about these. I have something to add. I am fitting them to an S4. I was concerned about the nipping busines when the crush tubes are tightened up. I am using Super flex. I have standard Lotus upper front bones and I checked the bush concerning the crush tube being longer than the bobbin (bush). They were befoe fitting and are still after the tube was pushed in the bush. I tried them on and all is fine with the nuts tightened.

However, my bottom front bones are not Lotus ones. When I fitted the Bobbins (bush) they were fine until the tube was pushed in. This was hard to push in and the poly was distroted and ends up with the side proud of the crush tube.

Comparing the measurement with that of the Lotus bones concludes that the inner diameter of the non Lotus ones are approx 0.4mm less. Hence this give the problem as the Poly must moe some were.

I have dropped them off for reaming to the lotus size. I am sure the Poly bushes get unfair bad press because of minor things like this. Before I comit to springs and dampers, I will ensure that the assembled bones with the nuts torqued up will allow suspension travel.

Thought I would share this as it is quite subtle and had I not read the other artical and gone ahead I am sure I would have had stiff susepension at the front.


Mike.
Mike

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PostPost by: rgh0 » Sat Dec 11, 2004 1:40 am

Mike

A good observation. The tolerances of the suspension components were orginally set to match up with the compliance given by the rubber bushes. Putting in plastic bushes of any type creates a whole new problem in terms of the tolerances on the arms

eg bush hole diameter, arm length and arm angle. The plastics bushes will not accomodate as much variation in any of these and pontentially cause the suspension to lock up or make assembly difficult.

The same problem arises in many other areas such as engines when people modifiy components without understanding how the assembly tolerances all stacked up both originally and with their modification.

Rohan
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