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S3 wheel alignment - close enough? - Suspension/Brakes/Wheels/Hubs/Steering/Geo - The Lotus Forums Jump to content
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slewthy

S3 wheel alignment - close enough?

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OK, last few jobs left before MOT now. :thumbsup:

 

I have just been assessing the geo after a full rebuild with new chassis.

Method I used was as follows.

 

4 axle stands at wheel centre height. Heavy duty fishing line strung parallel to the car (tensioned with elastic bands)

I ensured that the lines were parallel whist also equidistant from the rear wheel centres and also equidistant from the front wheel centres.

I got this (apparently) accurate to 1mm after several measurements and re-measurements.

I then measured front wheel toe-in and rear wheel toe-in.

I was able to correct the front wheels easily by adjusting the tie-rod ends.

 

Rear wheels have a toe in of 6mm and 7 mm each. This is obviously alot more than recommened but just how anal do I need to be about this? Is it just a tyre wear issue or handling too? Is this a huge error or minimal?

Anyone know how much shim will need to be removed at the trailing arm to chassis end to correct this?

 

Cheers!

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That much over could impact handling as it will be quite a bit of rear grip lost. to work out how much shim movement you need you may want to employ the of MS Excel (or other spreadsheet) you don't really need trigonometry, it's just a ratio.

Length of arm (centre of bolt to centre of hub) : rim diameter of wheel 

=

Thickness of shim added :reduction of toe in.

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Andy, thats great help.

I'll measure up and correct with the shim and then get a proper alignment done.

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I need to do my toe in. What did you connect your elastic bands to? Also as you were on axle stands do you think your rear toe in value may have been slightly amiss because isnt the arc of the arm not set square to the car? I mean if the wheel is dangling down could this read differently that if the car is sitting on its wheels half laden? I think the fishing line has to be better than a bar of steel as bars of steel are all over the place in my experience!

 

Buddsy

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No, the line is tensioned between the axle stands. Car is at ride height, suspension torqued up.

 

hope that makes sense!

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Oh yes now I see. Car not on axle stands, fishing wire is! Sounds a good plan I was trying to think of a way to do this job so may go for this method.

 

Buddsy :unworthy:

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The other thing I did which made it easier is this. 

Roughly get the distance from lines to wheel centre and cut some dowel to slightly shorter than this. One for the front, one for the back. Then screw a woodscrew into the end. This can then be screwed in and out to accurately change the length and see how far things are out. The eye can easily gauge mm differences when they are just 1 or 2.

 

When assessing the rim distance from the line, just mark on the dowel and take the difference. It seems to me that all of this gives an accuracy of about (but not better than) 2mm. Should be OK for rears but front toe in is of the order 1.6mm +0-1, so this method doesnt quite get you there. But you should be in the ball park.

BTW, I got some 50lb fluorescent line - I only tripped over it once   :rant:

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once you have had the toe in checked and in within limit, park the car a set distance from a wall or garage door ( the farther the better) and put a laser level on the rims/tyre pointing towards the chosen point then measure the distance of the laser point on the wall/door. If you use the same distance and width between points each time, it should always be right. The only time it may be necessary to re-check the laser point distance is when a different make of tyre is fitted. :)

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NIce - like that idea.

 

Infact, after my geo and adjustment, I looked at my front wheels and thought I had toe out. I forgot to account for the curve of the nose!

I then wrongly assumed that I had adjusted in the wrong direction. Therefore, I incorrectly over adjusted toe in. Cripes!!! It would abrely move forward & bacwards. Forget turning.

If you ever want a clear isea of tyre scrubbing/wear, do that (no, dont)

 

Anyway, I stopped being a cheapskate and forked out for a Trakrite roll over gauge. I will post results...

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I have used the same system as described, with the axle stands...but I used some spare model aeroplane control line wire! System worked well.....but now I've bought one of these:

http://www.ebay.co.uk/itm/Trackace-Laser-Wheel-Alignment-System-Tracking-Gauges-Toe-in-Out-Tool-Tracker-/300814333955?pt=UK_Measuring_Tools_Levels&hash=item4609ee7803

 

Haven't got round to using it yet, though.....

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Yup - I did think that looked good, just too pricey for me. 

I noted that you used control line but I wasn't exactly sure what you meant. Anyway, the tensioned fishing line went nice and straight with little to no sag. Which is the main aim.

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I had some 3 strand lightweight Laystrate left over from the control line combat days...great stuff for taking a pretty high tension without any stretch. Once I got the lines tensioned I measured from them to the wheel rim with a digital vernier caliper. A nice iterative process...I ended up deciding that the alignment was as accurate as I could get within the error limits of the method!

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