Gauges for measuring Wheel Alignment

Having always been miffed at the prices charged for adjusting tracking (yeah, I know that garages and tyre fitters have to claw back the cost of their expensive computer controlled kit somehow but 20 quid for 10 minutes work ?) I borrowed a "Gunsons Wheeltrue" device from a work colleague and was very impressed at how simple and repeatable the results were. It's a pretty simple setup comprising what can best be described as two lengths of steel U-channel that you attach to the wheel using a pair of bungee straps so that the "reference points" on them are touching the wheel rim. You then measure the distance between the ends of the U- Channels both in front of and behind the wheel and from the difference, calculate the tow in/out. The problem is that Gunsons don't appear to make these guages any more, the only alternative on their web site being a kind of "scuff plate" that you drive over costing about 50-60 quid. Does anyone know of any other sensibly priced guages or devices for measuring wheel alignment on the market ? It's the kind of thing that would be very handy to have around to do a quick regular check rather than wait till the obvious uneven tyre wear lets you know that all is not well.

Reply to
Roger Shilcock
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In message , Roger Shilcock writes

The place I previously used for tyres used the plate thingy (Gunson Trakrite) all the time and reckoned it was very good. I also thought about getting one but at £51 plus VAT, I though it a bit pricey for what it was.

Reply to
Paul Giverin

You could make one from electrical conduit / gas pipe / copper pipe and 4 'T' fittings. Only need one as the gap is fixed so you can't get errors from different settings. (ascii art use fixed pitch font to view)

T T | | | | ____________________________________________________

Legs of 'U' to match hub height, width of 'U' to be larger than outside rim to rim measurement. Slide under car, rotate to vertical and put one T on rim, hold in place with strap or assistant. Go to other side and measure gap from 'T' to rim. Undo strap and move it to other side of rim by pushing round back of tyre and pulling to clear other side. Measure again. rear - front = toe in if -ve and toe out if +ve. If don't you like the inversion slide a tube though one of the 'T's and measure protrusion of tube from 'T'. Some toe in meaurements are given at the trye tead.

Not too sure how to check thrust (rwd / fwd drag?) line easily as it requires rear toe in to be split equally on left and right. This would require a long straight edge rod/bar/plank from front to rear at hub height. Set edge away front hub center and rear hub center so it is parallel to car center line, front and rear offset depends on front and rear track. But if the chassis is not straight eg. whole front end offset 5mm to one side. this will be wrong! (10mm over 2500mm wheelbase is about 14 seconds - about 1/2 the typical setting range allowed) Check distance from front and rear of rear wheel rim to straight edge. Uneven left right split of tracking at front will just move the steering wheel to an off center position. Uneven split of rear tracking will make car go sideways with steering wheel straight ahead 'hands off' but so can many other suspension defects - camber, sagging springs, worn bearings/bushes, bent arms, front or rear subframe offset etc (must have missed some).

To check camber get two 20cm sprit levels (2 for £2 at poundland!). Check car is level side to side and fore aft - use cross member. Hold one level vertical against rim with mid point at hub height so both ends touch rim. Check it is vertical using other level set at

90degrees to first. Keeping one end on rim move level away from rim at other end to get both levels vertical. Measure 'gap' at top or bottom (nearest 0.5mm or 1/32 will do for around 10 second accuracy). Measure 'gauge' distance between contact point on rim and measurement point on rim

Camber = arctan(gap/gauge). Gap at top is -ve camber, gap at bottom is +ve camber.

My car has front camber spec of -1deg25sec to +5sec. On a 200mm level this gives a permitted range from 0.28mm gap at bottom to 4.94mm at top with a nominal of 2.62mm gap at top.

If you can't get the car level then set the bubble on the one checking for vertical to match bubble displacement fore/aft. Side to side move level to center bubble and measure gap. Add/subtract this gap from/to rim gap as required, if the sign changes it means the gap has moved from top to bottom or bottom to top.

-- Peter Hill Spamtrap reply domain as per NNTP-Posting-Host in header Can of worms - what every fisherman wants. Can of worms - what every PC owner gets!

Reply to
Peter Hill

Peter Hill wrote in news: snipped-for-privacy@4ax.com:

I've seen this kind of thing described elsewhere but it struck me as a bit fiddly to use and you have to know where the tow in/out is to be measured if in millimeters whereas the "Wheeltrue" gauge I've borrowed takes away the need for any calculations and the Haynes Manual gives required tow in degrees/minutes. If the scuff plate type was a bit more sensibly priced I'd buy one of those :-(

Reply to
Roger Shilcock

The Gunsons Wheeltrue tracking bars give a result in degrees toe in/out.

sPoNix

Reply to
sPoNiX

That's because alot of them are out due to repeated kerbing, potholes=20 driving up kerbs etc.

--=20 ________________________ Conor Turton conor snipped-for-privacy@hotmail.com ICQ:31909763 ________________________

Reply to
Conor

Conor wrote in news:MPG.19a3145bd1514a5f989dc0 @news.theplanet.net:

That'll be down to my wife's driving when I'm not in the car then ;-)

Reply to
Roger Shilcock

Do you think ' sleeping policeman ' can alter the adjustment ?

Andy

Reply to
Andy Coleman

I reckon so. I drive over at least 30 a day, the sort that you can just straddle if your car's track is wide enough. I reckon they will have a lot more effect on tracking than the normal sort. They're bloody useless IMO - cause people driving at and below the limit a lot of hassle, but hit one at

40mph upwards and you won't feel it.
Reply to
Doki

Really? So what bends to adjust the tracking then? ITYF it always needs adjusting at tyre places because they are staffed by clueless idiots.

John

Reply to
John Greystrong

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