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MG MGB Technical - Front wheel tracking

I have just changed the front N/S track rod end on my B due to it being worn. Does anyone know a way of checking the front wheel tracking, or is it impossible to check at home? I ensured that nothing changed during the operation (lengths etc) so it should be as it was, but i just want to check it anyway. If it matters, it's a '73 mgb roadster, with wires. Many thanks in anticipation.

Dave
David Evans

I used a technique that has worked on motorcycles to ensure that the front and rear wheels are pointing in the same direction:

1.) Take one small object that weighs a few pounds and tie one end of a 25 foot length of string onto. fire extinguishers work great for this!
2.) Place this fire extinguisher in front of one of the front tires.
3.) Run the string to the rear of the car and tie it to the inside of the rear tire that is on the same side as the one with the fire extinguisher in front of it. It should be tied approximately 4 inches from the floor.
4.)Pull the fire extinguisher forward so that the string is tight.
5.) Position the fire extinguisher so that the string is lightly touching the front and rear of both tires on that side.
6.) Turn the steering wheel straight ahead. This will occur when the distance from the string to the front of the front wheel is equal to the distance from the string to the rear of the front wheel.
7.) You have now established a straight line perpendicular to the rear axle.
8.) Pull out another fire extinguisher and piece of string and do the same thing with the other side of the car.
9.) You now have two lines that you can use to set the toe-in of the front wheels.
10.)The amount of "toe-in" specified in the service manual is measured by measuring the distance from each string to the front of the front wheels, when the rear of the front wheels are just barely touching the string.
11.) Adjust the toe-in by lengthening or shortening the tie rods. You will probably have to tweak the steering wheel to the left and right to get it exactly centered.

And you're done! All comments on the validity of this method are welcome, but remember, it works for me! If anybody says anything extremely nasty about my procedure, I will probably resort to questions of the parentage of the doubting questioner.

And no, I've never worked in an alignment shop, but that doesn't stop me from entertaining the neighbors with old British cars, string, fire extinguishers and beer!
Tom Wright

Tom, Ingenious method, but just to clariy a few points... In point 3. How do you tie the string to the Tyre? In point 5. I assume that ideally the string has to touch only the front and rear of the rear tyres? thus giving a perpendicular line to the rear axle which is only slightly inaccurate as it depends on the tyre walls rather than the wheels. However....doesn't the string also touch the front wheels (the front and rear track are the same - and you have the same tyres front and back - right?) This would surely affect point 10. as measurement has to be to the rims for accuracy (or is this why you say the string must be "barely touching" the rear of the front tyres? BTW my parents were married AFAIK (at least they were when I was born) - but that doesn't stop me being pedantic (purely in the interests of scientific accuracy you understand).
i.thomson

The method suggested by Tom has been used by circle track racers to make quick
alignment checks for many years. I use two jack stands to tie the string and move the
stands as needed to get the string parallel. Yes, the rims should be more accurate than
the tire sidewalls but I have found if you have a good tire and rim there is very little or no
difference. You can move the strings out from the rear wheels by making careful
measurements from the rear wheel sidewalls or rims. In any case I agree with Tom, it
works if done carefully.

Years ago I made a toe bar from a length of rigid plastic pipe. I used two short 2 x 4's
as stands and two steel rods for pointers. I drilled holes big enough for the pipe in the
2 x 4's so the bar would sit about four inches from the floor, you don't want it to touch
the underside of the car. Fasten one stand to the end of the pipe and on the other end
the stand should slide, I used a set screw to keep it in place. Drill holes for the steel
pointers near the top of the stand, insert the pointers and glue or epoxy them. You now
have a toe gauge that can be used to set toe anytime you make changes to your
front end components. I still use the string to get the front wheels parallel to the rear.
Then I place the toe bar under car behind the front wheels and slide the adjustable stand
to contact the sidewall, lock the set screw. Next move the bar to the front and if you
have toe in the bar will fit over the side walls and you can measure the distance from
the side wall to the pointer for the toe in. Make adjustments as necessary. If you
have toe out you will need to reset the bar and go back to the rear of the front wheels.

So to answer David's question you can check tracking at home with a few simple
devices.

FWIW, Clifton

Clifton Gordon

What are the toe in specs for a 77B? How would that measure up with the method described by Tom?
Thanks
Mark
Mark Rotsky

Mark, according to Haynes the toe in for all MGB's is 1/16" to 3/32". With Tom's method
after you have established the two strings perpendicular to the rear axle measure the
distance from the string to the front side wall of the front tire. The fact we are working
with only 1/16" toe in you may get better accuracy by adjusting on one side only.
Just keep the other wheel parallel to the string. Remember, if you make a big adjustment
on one side only the steering wheel will be off center so adjusting 1/2 of the adjustment
on each side will help keep the steering wheel on center. Clifton
Clifton Gordon

Invest in a gunson's Trackrite. I've been using one for some years and it works perfectly!
Miles Banister

Unscientifically, If you dry pavement in front of your house. Wet a strip of payment with your garden hose and drive straight through it. There should be only one set of tracks per side.
DAVE GJERSTAD

Thanks Tom and Clifton,
That seems like a clear and easy way to go.
Mark
Mark Rotsky

Tom's method is all very well, but how do I hang my car up by its rear? Maybe I should just stand it on its nose ...
Paul Hunt

The car can be hung up from the rear by very careful adjustment of the internal johnson rods. :)
Tom Wright

I have used the alignment gauge that Moss sells
for about $40.00 with good results on both
my B and midget. After several thousand miles,
no unusual tire wear or driving characteristics.
Its better to have two people using this
alignment gauge however, to make sure that
the L-shaped side is firmly against the tire.

Ronald

The string technique sounds very interesting, I will try it the next time I check toe-in. My usual high tech tool for this job is made from two yard sticks, (meter sticks for you folks with metric imposed upon you) and a C-clamp. Or, two straight unmarked sticks and a tape measure.
Paul Briggs

As a really rough guide I just sight down the outside of the front wheels and adjust until I just can't see the outside of the rear wheels.

This usually gets me to about 1/8 toe in which is fine till I take it to a tyre shop for accurate adjustment - since it only costs a tenner ($15) and includes a free recheck after 500 miles, it's cheap enough considering the cost of tyres!

Chris at www.octarine-services.fsnet.co.uk

This thread was discussed between 10/10/2001 and 14/10/2001

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