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MG MGB Technical - Front Wheel Alignment

Hi All,
Does anyone know of a method of setting the toe in on a 72 B GT without taking the car to a garage or quickfit centre to let a 15 year old loose on it.

Cheers

Steve
Stephen Farr

You can use the string method.

Here's a link that I found doing a quick search...

http://forums.nasioc.com/forums/showthread.php?t=1093484


I haven't read through it all. It talks about 4-wheel alignment, where the rear is adjustable. You can ignore that bit, but the general principle is the same.

I have used the string method on my ex-race car and, when checked with 'proper' tracking gauges, was found to be spot-on.
Dave O'Neill 2

Thanks Dave I will try and have a go with the string this weekend.

Steve
Stephen Farr

My Toyota Workshop Manual describes a method of using a bar which lies on the ground, with two pointers that reach up to points on the tyres in the same horizontal plane as the axles. Slide the bar under the car, say, behind the wheels and adjust these pointers to point to a given point on the tread and make a mark. Remove the bar, roll the car forwards or back half a revolution on flat and level ground until the mark is at the other side of the tyre, and using the bar and pointers on the other side of the wheels set as before see how far the pointers are from the marked point. That is the toe.

The front-to-back string method relies on the wheels being exactly behind one another, which may not be the case on an MGB if it has had the hubs and wheels changed between centre-lock and 4-stud.
Paul Hunt 2

<<The front-to-back string method relies on the wheels being exactly behind one another>>

Paul, that's not the case.

As long as the strings are parallel, it doesn't matter if the track is different front and back.

Dave O'Neill 2

I've been using a gunson's Trakrite for the better part of 15 years now - not only for the B, but also for a variety of front and rear wheel drive cars owned by family and friends. It's easy to use and seems to produce an accurate result.
Miles Banister

Steve-
Jack the car back up until the tires clear the floor. Hold a piece of chalk firmly against something stable with the tip just touching the measured center of the tire tread and then have an assistant rotate the wheel so that the chalk can make a mark on the rubber all the way around the tire. Repeat this process on the other front tire also.

Lower the car onto the floor and bounce the front end of the car in order to settle the suspension again. With an assistant, use a flexible tape measure to gauge the distance between the lines on the tires both on the fronts of the tires and the rears. You might want to do the rear measurement first as you will have to thread the tape between the body and the down pipe of the exhaust system, stretching the tape as high up as you can without fouling anything. When you measure at the front of the tires, try to take the measurement at about the same height off of the floor as you did on the rear measurement. Compare the readings. Remember to loosen the cinch clamp at the small end of the gaiters(boots) before you try to rotate the tie rod. Be aware that making all of the adjustment on one steering arm will move the steering wheel from being visibly central whenever the car is driving straight ahead. Making equal amounts of toe adjustment on each tie rod keeps the steering wheel pointing to where it was before the adjustment is made. Your goal should be to end up with the front measurement being 1/8th of an inch less than the rear measurement. If it is not, re-sight each wheel in turn and adjust the tie rod ends as carefully as you can to get the sight line to the rear wheel just right. Work with this measurement and sightings and adjustment process until the front wheels are "toed in" 1/8th of an inch, then tighten the jamb nuts on the tie rod end, and then tighten the small cinch clamps around the ends of the rack gaiters (boots).

Now, take the car out for a test drive. If the car is lacking in directional stability, the odds are that the wheels are not toed-in enough. If it feels a little imprecise, then the toe setting is probably excessive. Castor should be within 4 ½° to 5°; front camber should be -¼° to -½°, while the optimal toe-in can be anywhere from 0” to 1/6”. “Toe” effects both wheels equally even if you make all the adjustment on the one wheel. Work with the toe adjustment as needed to get the correct sight lines, the correct toe measurement, and the best “feel” when driving. The castor angle is more or less equal on both sides. This being the case, it ensures that when driving forwards on a flat straight surface the wheels will always take up an equal angle from straight ahead, i.e., half the total toe-in (or out) on each wheel.
Steve S.

You would have to measure between the strings to ensure they were parallel, which would mean four jack-stands and two strings, or at least accurately measure the track front and rear before-hand, and it still relies on the rear track being centred exactly on the front track. I certainly wouldn't rely on the book figure for track to set something as important as toe. Without a trip to a tyre place or a Trakrite I still believe the rod and pointer method is far easier and more likely to be accurate than the string as it compares one distance with another and only the difference between them is important, the actual distances in each case are irrelevant.
Paul Hunt 2

This thread was discussed between 17/10/2007 and 22/10/2007

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