1" fine threads-.100
 

How many half turns of my ladder bar rod end will I need to make up for the .100" mid plate I am installing ? I want my axles in the same spot or close as I can get it.
Figured some of you machinist types would know.
Thanks for any help.

Darn good question!
It would likely be pretty darn close to the amount of movement you get from one rotion of our Pontiacs 15/16" fine threaded balancer bolt I would have to say .

1" fine thread pitch is 12 threads per inch. So each full revolution equals .083". So, a tiny bit over two half turns.

JSchmitz is correct.

For all SAE fasteners.

1 ÷ TPI = Pitch

1 ÷ 12 = .083 Distance moved per revolution

Dave

If a 6-sided nut on it, would be about 7 'flats' to get the distance.
(almost 7 and 1/4 flats)

:)

I assumed he only had the option of half turn increments.

Could be. He's in the Street section.
My bars have a 'nut' on the bar for easy turning. Most ladder bars I've seen have those.


But however you get there, it's a little over 1 revolution.


:)

Agreed...

Thanks, this mid plate is a lot more work than I thought. If I am going to go through all this I might as well set it up for my custom Mad Dog 2 " headers, slip fits so I might as well buy the merge collectors while I am at it.
Who needs money anyway ?
Either all that and not run the mid plate and just run my elephant ears. But I do not want to take a chance.

I guess I don't understand what's going on.

You're mounting the engine with a mid-plate. This pushes the transmission rearward by the thickness of that mid-plate.

The transmission has a slip-yoke at the rear for the driveshaft connection. The rearward transmission causes the splines to engage more deeply.

None of which changes the location of the axle. The axle doesn't move when the transmission is crammed rearward so long as the output shaft/driveshaft yoke splines don't bottom out.

So to my thinking, you have no reason to adjust the axle-locating linkage. The "answer" is "zero half-turns".

You MIGHT have reason to shorten the driveshaft by the amount the transmission is moved rearward.

Am I wrong? Not understanding something everyone else "gets"?

How much does that mid plate weigh and how much does adding that weight and moving the trans rearward effect the overall weight distribution/ percentage of front to rear?

I guess I could have been more clear.
My drive line is almost too long. If it was a 1/2" shorter it would be nice. Its tight getting my U joint out of the yoke on the 9".
Nothing binds up, I have ran the axle all the way up and down as far as you can go (drive line hits the ladder bar cross member if you go too low) during mock up testing.
So there is not a lot of room to slip the trans yoke forward. .100 matters in my case. So I need my rear axle to be in the same place as before the mid plate.
And getting some more thread from my main rod ends will be a good thing.

The mid plate does not weigh much. .100 thick steel. Its a Alston unit and big enough for a chassis car. But by the time I am done cutting it up it will not be all that big.
Maybe I will put up a pic of what is left of it when I get that for into it. Right now I have several cardboard cutouts of my full mid plate.
There will be a lot of trim, fit, check, trimming of the cardboard before I actually cut the steel plate. I will need to have the trans and drive line all in the car with elephant ears in place before I weld anything.
And the headers will have to fit in there too. Thats why I might as well get my best set of headers have everything all dialed in and powder coat them inside and out.
Going to be a lot of work. Good thing metal fabricating is part of my job.

This still sounds like a driveshaft-length problem, not a ladder-bar adjustment problem.

If you need your axle to be "in the same place", DON'T dick with the axle adjustment.

Is this for a Tempest?
I think if it were me I stay with what you have already
Thats what I made for my Tempest and works well

GT

How do you figure ? There is no driveshaft length problem with my car. Its just close, thats all. The front yoke does not bottom out on the T400 output shaft at any point, it can't.
Not sure why you say its a driveshaft length problem ?
Just looking for how many half turns to take up the .100 distance I am pushing the rear U joint back.
Looks like 1 1/2 half turns of the front rod ends will bring the rear ..125 forward after pushing it back .100
So I gain .025 more room getting the rear U joint out of the yoke for drive line removal and 1 1/2 threads more engagement on my rod ends.
Win,win.
.025 is close enough. Will never notice it and a lot easier than shortening and re-balancing my Strange drive line.

BTW, who makes the good 1350 U joints these days ? The kind with no grease zerk. These have been on forever, still in good shape.

Its a 69 GTO. Simple A body with Alston 32" adjustable ladder bars.
Pump gas, so we will call it "street".

IF you are not bottoming the splines on the U-joint yoke, you ARE NOT pushing the rear U-joint rearward.

THEREFORE, there is no need to move the axle via the ladder-bar adjustment. You want your axle "in the same spot or close as I can get it." So don't move it. It's already where you want it.

But moving the transmission rearward may take up the clearance you currently have with the splines. So MAYBE you need to shorten the driveshaft.

I don't understand this at all. If you move the rear axle .125 forward, and the transmission goes rearward .100, you LOSE .225 clearance at the yoke splines that you're already tight on.

Schurkey, it should have been one full turn for .083. I added a half turn for some reason and went the wrong way. I was trying to type this with company over. Too tired for company anyway. Day shift after a night shift with 3 hours sleep.
So its trans back .100 and extending rod ends one turn for .083 or one and a half for .125 .
I will be fine with the rear .083 back and there should be enough slip on the yoke for the .017 difference.
If for some reason I don't like it I will bite the bullet and buy a carbon fiber driveshaft. Been wanting one anyway, its a good excuse.