[chiphead]

My '67 LeMans was converted to 400/TH400 by a PO. I think the TH400 is a short-tail but I'm not an expert. Looks like the stock ST-300 driveshaft was shortened and a TH400 yoke added. I've since swapped the BOP 10 bolt for a Ford 9 with 1330 short/wide yoke.

The driveshaft still fits, but likely needs to be at least 3/8" longer than what it is. I need the following dimensions to confirm what length I need.

What is length (center-center of U-joints) for '67 GTO shaft with TH400?
What was barrel length of '67 GTO TH400 yoke?
What length tailhousing did a '67 GTO TH400 have?
How much barrel stick-out should I have at ride height?

[HWYSTR455]

Just measure for a new shaft, using the people's guide/recommendation for measurements, and provide that to have the new one made.

Everyone does the measurements a little different, let them figure it out.

If you're old shaft has already been shortened once, throw it in the trash. For that matter, any 50 year old OE shaft should go in the trash, especially on any performance app.


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[HWYSTR455]

If the slip yoke doesn't have proper engagement with the tailshaft bushing, it will eat it.


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[Mr Twister]

Here's what I did when I had a driveshaft made for my G-body Grand Prix:
-Find the yoke you want to use (there are different lengths for a TH400)
-Wrap a ring of 3/4 painters tape around it on the u joint end. Put it in the tail shaft up to the tape.
-With the cars weight on its wheels, measure center to center where the u joint caps would be on the front and rear yokes.
-Provide your builder with the front yoke and tell them what you are running on the rear end, along with your measurement.
-Should be all set.

[HWYSTR455]

Like I mentioned, most shops have their' own way of measuring, and you need to provide the numbers the way they WANT the numbers, or it won't be right.

Most shops even if you try to give them a measurement will tell you to measure THEIR way or they won't do it.

This is The Driveshaft Shop's measurement requirements, take a look, and compare to other shops:

https://driveshaftshop.com/custom-driveshafts/

They don't let you choose how much protrusion there is of a slip yoke, they go flange to flange, period. THEY calculate the amount of protrusion.

Here's Dennys:

https://www.dennysdriveshaft.com/how_to_measure.html

I have had enough driveshafts done to know you as the people that are making the shaft what they want. It's not hard.

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[HWYSTR455]

Your local 'regular' driveshaft shop will no doubt have their' own way too. Just call them.




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[HWYSTR455]

Just to say it out loud, at max rear suspension compression is when the slip yoke goes the furthest into the trans. So it can vary on setup to setup.



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[gassman_67]

I have a TH400 shaft from my 67 GTO with new ujoints installed for sale, if interested. I went to a Ford 9" with a Strange shaft

[chiphead]

Circling back to this. Attached is a picture of what I've got now. You can see the amount of yoke stick-out. The shiny area is how much more is sticking out with the Ford 9" rear. You can also see the weld where the d-shaft was shortened like 20+ years ago.

Is this OK to run or is it sticking out too far? If I have a new shaft made, about how much longer does it need to be? I'm going to call the local shop, but I'd like to see what you guys say.

The rear suspension is lifted by about 1.5" inches by some spring spacers. Otherwise the 275DRs don't clear. It rides good and doesn't wheel hop. How much does that impact how much yoke stick-out I should want?

[HWYSTR455]

Of course that's not ok. Not only is it not full engaging the splines, it's not fully supported by the tailshaft bushing.

Get a new shaft made, that's the answer. No matter how many times the question is asked, the answer is still the same.


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[HWYSTR455]

A 1.5" rise in suspension is going to have little effect on the slip yoke engagement. Probably not even measurable.


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