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MG TD TF 1500 - Toe in

A recent post suggested toe in to avoid wheels "hunting" for a straight line. I am at "0" toe in/out and want to adjust to toe in. Does anyone have a number of how many threads/turns to pull the tie rod ends in-board?
Peter Dahlquist

My TF is set at 1/16th inch toe in between the most forward and most rearward wheel rim edge. Sorry but I don't know the thread count. PJ
P. Jennings

I seem to have mine tweaked in between 1/16 and 1/8. I honestly can't feel any different between 0 and the slightly toed. But then again I only just recently got my TD up over 45mph.
L Rutt

Gents,

When I purchased my 53 TD it was slightly toed out and needed continuous steering correction at 60 MPH. I reset toe in to 1/8 inch with a home made toe in gage. It now tracks without continuous correction. No apparent tire wear but not many miles either. Maybe 2000 miles over the last five years.


Jim Haskins
J. M. Haskins

Peter,

(Incidentally, it would be easier to simply put a piece of tape with a mark on each tire tread, measure across the front in a straight line, push the car backwards and measure straight across as high as you can as the oil sump will interfere, and then adjust the tie rods for 1/2 of the change you desire. i.e if you want 1/8th toe-in, adjust the tie rods to give you 1/16 wider in the rear marks) and then remeasure the front. The difference back - front = positive number is the toe-in. I personally wouldn't use any thing else to measure as the rims may be bent, etc.)

Or... per your request- I don't have my TD around right now, but it depends on the thread used on the tie rod end. I don't know what is most common.

1) Measure the width across the flats of the locking nut, or determine which Whitworth wrench fits the nut. Keep in mind that these will be fine thread, so the size of the threaded portion will be one size smaller than that listed on the wrench (Whitworth is the 'Course' thread in the British system). If your wrenches are marked 'BSF' then you can proceed to step 3.

2) Determine outside dia:
7/16" Whitworth Wrench is 3/8" BSF O.D.
1/2" Whitworth Wrench is 7/16" BSF O.D.
9/16" Whitworth Wrench is 1/2" BSF O.D.

3) Determine threads per inch:
3/8" BSF is 16 tpi
7/16" BSF is 14 tpi
1/2" BSF is 12 tpi

4) Realizing that 1/8" increase in toe-in requires 1/16" decrease at the front of the tires, and if you want to adjust both tires equally, you need to change each 1/32" (.3125 each), Do the math:

1/16 tpi is .0625 change for one full turn of the nut, or .0104 per flat, or .3125 is three flats for each tie rod end, or 180 degrees.

1/14 tpi is .0714 change for one full turn of the nut, or .0119 per flat, or .3125 is 2.6 flats for each tie rod end, or 157 degrees.

1/12 tpi is .0833 change for one full turn of the nut or .0139 per flat, or .3125 is 2.25 flats for each tie rod end, or 135 degrees.

If you have Americanized ends you will have to discover your threads per inch and do your own calculations... so you can see why it might be easier just to do it with tape and marks.

warmly,
dave

Dave Braun

The change in toe is approximately 4x the amount the TRE (total) are changed. The TRE is about 1/2 the distance from the swivel axis to the tread, so the tread moves 2x the TRE distance, plus 2x for the back side of the wheel.

Dave has BSF and Whitworth confused.
1/2 BSF = 16 TPI; 1/2W = 12 TPI
9/16BSF = 16 TPI; 9/16W = 12 TPI
These two sizes happen to have the same TPI for both 1/2 & 9/16, I believe the TD are 9/16 - 16 BSF.

So, to change toe by 1/8" the total TRE change is .125/4 = .03125, divided by 2 for each TRE change, or .0156 each side = about 1/4 turn of each Tie Rod.

But, especially with radial tires, there is no good reason to have toe at other than 0 to 1/32 IN. Any Toe OUT will lead to instability.

FRM
FR Millmore

Hmmmmm Darn it Fletcher, I sure do. Stupid tiny charts... and I should have thought of the arm length difference relative to the tire tread fronts. Oh well, my original statement to measure was good... LOL.

Thanks for the correction.

warmly,
dave

Dave Braun

Never much good with math- above way too complicated for me! How about the string/ruler method? George
George Butz

Thank you everybody for the discussion. I was trying to avoid getting on my knees (they are getting awful stiff) and crawling around on the cement measuring stuff. Thought an hour laying on my creeper would be more pleasant.
Peter Dahlquist

The string method is good, fast and cheap!
The alignment shop in Campbell,Ca uses it for a quick check.
Basicly, you make a rectangular string box around the car that just touches the widest spot of the tires. It is then very easy to see which wheels are pointing straight ahead, including the rear wheels. This is something we usually take for granted, but...
chuck
cj schmit

This thread was discussed between 04/11/2011 and 07/11/2011

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