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Castor shims on Turbo SE 1990. - Page 2 - Suspension/Brakes/Wheels/Hubs/Steering/Geo - The Lotus Forums #ForTheOwners Jump to content


Castor shims on Turbo SE 1990.


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2 hours ago, Jacques said:

The problem is, that I cannot really get these in my country, as we are metric (fortunately), and every time I order something from abroad, they send me the thicker ones

I know exactly what you mean. Very few suppliers state the nut length in their spec. Looking through my box of nyloc nuts, I can see they are available in at least three different lengths including very slim ones, medium ones and very long ones like yours. My upper pivots do have plenty of spare thread visible so will accommodate an additional 4.5mm of shim washers.

2 hours ago, sailorbob said:

Another possibility is that the rubber has developed a 'memory' from having the wishbone arms splayed due to the incorrect combination of castor shim washers and plates

I can see, on mine, that the missing 4.5mm of shim washers, combined with the excess of ball joint shim plates, has caused the top bushes to deform slightly with the wish bones virtually rubbing on the outermost snubber washers. When I corrected the situation the std bushes (being quite soft) were very willing to conform to their normal alignment.

Andy.

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I may have found a small mg garagem who is willing to drive from his sommerhouse to his workshop, to sell me a bunch of ½" unf nuts. I have no idea as of yet, to the length of these nylock nuts. We'll see.

I measured up the contranuts I bought (from the UK) and they are only 0,15n too thick, so not a problem.

I did the other side today, and I also have an apprx. 8mm airspace between the upper ball joint and the rear upper wishbone arm. On both sides of the car, I inserted two 3mm, so 6mm in total, to fill it up. Should it be one 3mm each side to neutralise the effect on castor?

I am not able to measure <ny geo yet, but am collecting materials to do so, as soon as I get another purple front arb to lower wishbone arm bush, as one split completely while installing. (yes, I did use the tool)-So no measureing yet, to know where I am with castor so far.

I measured the LOTAC red poly bushings that is inserted into the upper wishbone arms, to be the exact same length. So at least I know that this is not the reason for such wild airgap next to the upper ball joint.

I now need to order more spares, as I don't have enough to swap it all, shims, nuts etc.

Kind regards,

Jacques

Nobody does it better - than Lotus ;)

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1 hour ago, Jacques said:

apprx. 8mm airspace between the upper ball joint and the rear upper wishbone arm. On both sides of the car, I inserted two 3mm, so 6mm in total, to fill it up. Should it be one 3mm each side to neutralise the effect on castor?

Hi Jacques,

If I understand Derek correctly, that's not correct. It's the wishbone pivot that should have 6mm of total shimming not the ball joint.

Andy.

 

 

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Yes, I already set that up. And that leaves me with the front of the two upper wishbone arms wide apart, so much, that when I insert a new fresh upper ball joint, There's still a wide opwn airgap. Hence the two shimplates I inserted today, to avoid twisting the bushes.

I am puzzled.

Kind regards,

jacques

Nobody does it better - than Lotus ;)

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yep, they are brand new LOTAC poly bushings. But i can take the arms off and measure if the inner tube runs parallel to the arm they are inserted in. They are not hard to press in (I also froze them first) and they shouldn't be damaged.

Kind regards,

jacques

Nobody does it better - than Lotus ;)

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That is close to the 37.5 mm width of a GT6 ball joint so that leaves the bushes as a possible explanation. Unless Lotus designed it that way.....  Anyone with 6 mm of castor shim washers and no castor shim plates have a gap when the ball joint nuts are removed?

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Hi Derek and Jacques,

For info, I looked at my front left suspension today.

I checked the castor first and it was 0 deg. (my SE owner's manual says it should be +1 deg to +1.5 deg max)

Took the wheel off and there was a 3mm shim washer to the rear of the chassis pivot mount.

And 4.5mm worth of shim plates to the rear of the ball joint.

The bushes were sat perfectly central between the snubber washers and when I released the ball joint bolts, the wishbones opened up a few mm only.

Andy.

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Thanks for the observations.

Derek, I believe that the new bushings are sitting perpendicular to their mountings, but I could be wrong. So, As I measured the width of the red poly LOTAC bushings to be the same width as the original rubber bushings, I also realised that they have quite a different shape. The original rubber bushings round off a bit each end, and have a semi-large more flat like endings. Where as the red LOTAC polybushings are ending their outer metal sleeve earlier, and the inner metal tube with a little bit of red polyurethan preotrudes a few mm each end. But as I said, the overall length is the same. I will go tomorrow and take a closer look at how the ends of these LOTAC bushings with their protruding ends behave in relation to the snubber washers and their bore. To the eye, it looks like they are aligned at each end, but I'll try to loosen the nuts, and observe what happens under different torque settings, to see, if the ends of the LOTAC bushings can tilt a little bit into the bore od the snubber washer. It's just a thought. Or I may take one wishbone arm off and measure  and try with the new and old snubber washers.

I'll report back here.

Andy: do you have original rubber bushings, aftermarket rubber bushings, aftermarket polybushings or LOTAC polybushings?

And do you have original snubber washers and shims, or aftermarket ones?

 

Thanks a lot for your suport so far.

Kind regards,

Jacques

Nobody does it better - than Lotus ;)

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34 minutes ago, Jacques said:

Andy: do you have original rubber bushings, aftermarket rubber bushings, aftermarket polybushings or LOTAC polybushings?

And do you have original snubber washers and shims, or aftermarket ones?

Hi Jacques,

I'm pretty sure from the rust and dirt that all my bushes, shims and snubber washers are the original factory items.

Only the springs and dampers are new.

Andy.

Edited by AndyPG
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