Pitman Arm Question

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Model T Ford Forum: Forum 2015: Pitman Arm Question
Top of pagePrevious messageNext messageBottom of page Link to this message  By Mike Walker, NW AR on Tuesday, March 31, 2015 - 10:02 pm:

Is the Pitman arm used in '26-7 any different from the '25-back ones?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Jim Thode Chehalis Washington on Tuesday, March 31, 2015 - 10:48 pm:

Looks like some of 26 27 are shorter.
See this thread:
http://www.mtfca.com/discus/messages/257047/300409.html

And:
http://www.mtfca.com/discus/messages/411944/452557.html?1402878003

Jim


Top of pagePrevious messageNext messageBottom of page Link to this message  By George_Cherry Hill NJ on Tuesday, March 31, 2015 - 11:53 pm:

The answer is T929C only applied to 26/27...but with a disclaimer Mike.

This is one of those questions that is never as simple as it seems. You do need to be careful as some parts can be mixed and matched and you by luck keep stable steering, and at other times mis-match would cause a lock-up over steer when you least expect it...and it is NOT just the pitman arm! The 26/27 is the worst of the breed on being least tolerant of mix-n-matches...

To really understand and not get caught sleeping at the switch with a hard left lock-up...You need the record of changes for the pitman arm...PLUS knowing that there is a C version and a B version...Plus knowing there are different length drag links depending on when manufactured...plus knowing there are different 'arc' distances and 'arc center angle' of lower gear case in the 4::1 era...plus knowing that if you stuff a 5::1 set into a great older lower case showing no signs of wear that you may turn in one direction but not in the other, but if you use a heavily worn one it still works...plus knowing that some 26/27 have a bad habit of stretching the arc degree total of the slot in the lower case by normal wear and even with all of the right parts you can get an over-steer...plus knowing that if anything else is but slightly amiss and your drag link is bent even in the least little bit it will now combine to cause an over-steer.

I can't do writes ups without going 25 pages on anything anyway, and I don't own a 26/27 myself (so in spite of rumors to the contrary I usually refrain from comment on things I don't own or have not worked deeply on)...but I do work on someone else's 26/27 from time to time and that puppy has gremlins neither the owner nor I have never been able to find!

Never an issue with the owner or me...rides fine, turns fine, one of the smoothest improved cars around...but let a newbie try? He'll go around in circles all day once he tries his first turn! By the numbers it checks out fine with input from guys here...the lower gear case does have a very extended slot caused by wear and someday when one of us sees a complete 26/27 column that is decent we are just going to buy and swap...

I just wish someone who has been completely through it and has a flair for writing would do an article in one of the magazines. It has to be by a guy who is actually rebuilding a 26/27 cause on the older ones? You can darned near mix anything you want together and they still work...even those without slots in the lower case....go figure!

In the meantime, if anyone has any questions on mix-n-match, there is a 'suspender' thing that George House came up with that prevents over-steer. Put it on until finding the cause of an over-steer, or heck, just leave it in... George House situation was like more than a few 26/27...he never had any issue, never had a steering wheel fight him or resist him, it always worked great and smooth for him...his daughter grew up with his T's, learned to drive one, first time went out solo managed to go over center and I think roll it...so George designed his Brama bull horns system which prevents it from ever going over center by geometry and with external stops! Wonder if the car is still that way or was ever resolved?


Top of pagePrevious messageNext messageBottom of page Link to this message  By R.V. Anderson on Wednesday, April 01, 2015 - 01:30 pm:

A genuine Ford arm should have the part number, T929C, on the upper end of the arm where the taper is, and the FORD script on the opposite side. The measurements for T-929C are: from the center of the ball to a line drawn tangent to the uppermost edge of the taper end is 4". From the center of the ball to a line drawn through the center of the tapered hole (this is 90 degrees from the previous measurement), it's 3-11/16".

These measurements are taken directly from the T-929C drawing.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mike Walker, NW AR on Wednesday, April 01, 2015 - 06:59 pm:

Thanks for the info, Guys.


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