Driveshaft Update With Pics!

Okay, so i'll start with the stock axle. Here it is:







Doesn't look like a 7.5 to me. I measured it and the 8.8 from diff cover to pinion flange and got:

stock: 10"

8.8: 12"

so the pinion flange on the 8.8 is 2 inches closer to the tailhousing.

Here are the driveshafts I have. In front is a T-bird Turbo Coupe driveshaft and in back is the stock Zephyr driveshaft.





The big thing on the trans end of the T-bird shaft is preventing it from fitting in the tailhousing because of how i improvised the crossmember. My trans sits higher than most so that thing hits the tunnel.

I'm wondering if i could swap the end of the Zephyr shaft onto the T-bird one. One problem might be i would lose some length. the piece from slip yoke to U-joint on the T-bird shaft is 7.5 inches and the Zephyr one is 6.5 inches. You can kind of see that in this pic.


This pic clearly illustrates the difference in length.

I'm pretty sure '83-88 T-birds have a different wheelbase from an F/Z and that's why i was wondering if anyone is using a driveshaft from one. It almost seems too short, so that's why i didn't want to lose the length at the skip yoke.

The driveshaft lengths are:

T-bird: 56.5"
Zephyr: 59"

What is the length of your driveshaft?

Wow...freaky. I have no idea...

Don

I would replace those yokes...the dampners on the yokes serve no purpose for any kind of performance car. Could you imagine if that dampner flew apart under the car and the kind of damage that it would cause. You might even free up a litttle horsepower by getting rid of a little drive line weight. Just curious as to how much those things weigh....especially the t-bird one.

Bryan

Just a quick note. The wheelbase information i can find on the T-bird/Cougar and F/Z:

'83-86 T-bird/Cougar: 104"
'87-88 T-bird/Cougar: 104.2"

'78-83 Fairmont/Zephyr: 105.5"

the F/Z also shares wheelbase with the Granada, square Cougar, and small LTD/Marquis.

So what that means is, most likely my T-bird driveshaft is too short. I wonder if there are any in the junkyard that haven't been wrecked...

That is an unusual looking axle. Is it possible to pull the cover and measure the ring gear diameter to determine if it is the uncommon 6 3/4" axle?

My Fairmont is a '78 and I had no problem switching from 7.5" to 8.8". Where I did run into problems was when I converted from C4 to T5. My observation seems to be that early Fairmonts (78-80) have shorter (about 1") transmissions and longer driveshafts than later F/Z models. However, everything fit great when I used a driveshaft from a later (1981) Fairmont along with the T5 and the 8.8. My junkyard measurements also suggested that driveshafts from a Granada are the same length as the later Fairmonts, but not driveshafts from the Fox LTD cars. I never did find a Cougar/T-Bird driveshaft that was the right length. It took me a while to find a straight driveshaft because of the way wrecking yards move vehicles around with a fork-lift.

I bet that axle is the 6.75. The easiest way to tell: Remove a brake drum and see if there's a hole in the axle flange, and a bearing retainer. If I'm not mistaken, the 6.75 has bearings like a 9", not c-clips.

You know, now that you say this I believe you're right. My mom's 78 had an oddball axle too. My sister put the car up against a curb sideways one day and broke the rear axle shaft (rain and speed on Woodward Ave don't mix). When the shop bought a new one they had to exchange it for some reason and I think it was because of the smaller, 6.75", axle.

I was 12 when it happened so had nothing to do with it. That's my story and I'm sticking to it.

Don

You can just read the diff. cover tag...I see it is still on the rearend.

jnorth8 wrote:

everything fit great when I used a driveshaft from a later (1981) Fairmont along with the T5 and the 8.8.

My understanding is that T5 cars use the same length driveshaft as AOD cars. Hopefully i can find one that hasn't been wrecked by forklift, like you say.

I do have another aluminum driveshaft laying around that's too long. is it possible to have it shortened? and if so, is it ridiculous money to do?

nah its cheap around here its only about a hundred bucks or less.