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Reference point for measuring rear wheels? Mk Indy
Banana - 22/2/17 at 12:21 PM

So i've recently heard that a lot of early Mk's suffered with severe rear wheel misalignment. Namely toe in on the rear left.

To check this, should i be measuring from the wishbone/chassis points to the outer wheel and comparing each side?

How many people have suffered with this?

thanks

40inches - 22/2/17 at 12:37 PM

I used a length of wood (old skirting board) with a couple of shelf brackets screwed on (bent strip would do) just inside the wheel rims, fitted a couple of long M6 screws level with the centre line of the wheel hubs. Adjusted the screws to just touch the rim at the front, moved to back of wheel and used a feeler gauge to measure the difference, less than 1mm.
I used the same "tool" to set the front wheel toe

Banana - 22/2/17 at 01:04 PM

I think i see what you mean..

Was that on your MK? What year was it out of interest?

40inches - 22/2/17 at 01:14 PM

quote:
Originally posted by Banana
I think i see what you mean..

Was that on your MK? What year was it out of interest?

My chassis was one of the first made by Martin Keenan, it may have been better or worse than the later MK ones
Google "String box" for setting up the geometry, a bit rudimentary, but was very close when I had mine checked on a Hunter system
I used fluorescent 1mm fishing line, I have most of a reel left if you want some?



[Edited on 22-2-17 by 40inches]

nick205 - 22/2/17 at 01:31 PM

I had 4 wheel alignment done by a local tyre specialist. It showed a small amount of toe out on one rear wheel. My Indy had no means of toe adjustment on the rear, but I sourced some shim washers and fitted them between the rear upright and Sierra bearing carrier - this corrected the toe when I had it re-checked. Not overly scientific, but a workable solution.

For reference mine was one of the last Indy chassis made by Martin Keenan. I don't know if that played any part in it's accuracy though.

[Edited on 22/2/17 by nick205]

Banana - 22/2/17 at 03:43 PM

Im familiar with the string box, but doesn't that work on the assumption the rear wheels are true?

I guess you would have to go from the center of each wheel then.
Say 100mm from the center of each and go from there.


Interesting you mention shim washers.. I thought the carrier hole needed to be opened up and have an offset washer welded in place.
Any pics would be great if you have some.

[Edited on 22/2/17 by Banana]

SJ - 22/2/17 at 04:30 PM

I checked mine with a Trakrite gauge that you drive over. My rear alignment was 1 degree toe in, so no need to adjust it. My chassis was built in 2006.

nick205 - 22/2/17 at 04:38 PM

quote:
Originally posted by Banana
Im familiar with the string box, but doesn't that work on the assumption the rear wheels are true?

I guess you would have to go from the center of each wheel then.
Say 100mm from the center of each and go from there.


Interesting you mention shim washers.. I thought the carrier hole needed to be opened up and have an offset washer welded in place.
Any pics would be great if you have some.

[Edited on 22/2/17 by Banana]



No photos I don't think.

The shim washers were pretty thin to alter the toe angle. Too thick and yes you'd probably have to open up the bearing carrier holes. To that degree I'd probably be considering new rear wishbones with rose joints to alter the toe angle.

Smoking Frog - 22/2/17 at 05:23 PM

quote:

Im familiar with the string box, but doesn't that work on the assumption the rear wheels are true?

No, it's capable of 4 wheel alignment. The "box" is independent of any existing wheel alignment. Usually set-up as you say using the centre of the hub.

907 - 22/2/17 at 08:31 PM

When I built my chassis everything was measured off and mounted to a centre line down the middle of the car.


Paul G