Guys,

I'm considering a 4 speed swap for my '65 Valiant, which has already been discussed on this forum.

Currently, the driveline is 904 with a 7 1/4 rear. These components have seen better days, but they are operational. I've been tossing around the idea that before I get into the 4 speed swap, I'd like to put an 8 3/4 in (which I have already) and drive it with the 904 for a while.

The reason for putting the 4 speed swap on hold mostly has to do with wheel size. I'm planning a disc brake swap, which generally requires 15" wheels to accommodate 11.75" cop rotors and calipers. That would leave me with the small-bolt rear end, which to my knowledge, I really can't get 15" wheels for. I'm was planning on putting the 8 3/4 in when I put the 4 speed in.

My question: can I re-use my existing driveshaft with the 8 3/4/904 combo or would I have to get a new shaft anyway? I imagine I might have to get a U-joint, but that's minimal compared to a new drive shaft.

Thanks,

Greg

I don't have my FSM handy but there is a page in the propeller shaft section that lists lengths.

Going off pure memory if you have rear end x, it doesn't matter what (stock) trans you have shaft length is same. But if going from one rear to another it does need to change as pinion lengths are different. The driveshaft for an 8 3/4" vs a 7 1/4" was real close to 2.25" shorter (something like 2.19"?)

Greg,

I read your inquiry as asking what driveshaft changes would be needed IF you KEEP the 7 /14 and ADD the 904. I may have gotten confused because you mixed in the 8 3/4 and 15 inch wheels, but it seems you don't want to put that in just yet (small bolts, etc vs. 4 1/2 x 5)

I went from a 3 speed to a 833OD. The 833OD and 904 are both longer than any 3 speed I have used. This would mean shortening your driveshaft is in order, and indeed I have had three shortened at different times.

You don't need a NEW one, just get an old one and have it shortened. I got two from junkyard and one from original vehicle. Most any good truck driveline place can fix you up,including welding on and balancing a large u-joint yoke, for about $125. Some old posts here will tell you where to measure, or email me. I finally went with truck driveshafts because they are about 3 1/2 inches in diameter are are stronger on that account than the car ones, which are a tad less than two inches diam. If you are going to swap in the 8 3/4 ( I did) my advice is to go on and put on a yoke in front (to tranny) for large joints for strength. Both yokes, driveshaft yoke adapters and u-joints are readily available.

rock
'64d100

If your 904 is the stock one for 65, you will have the ball & trunnion set-up instead of a slip joint u-joint. You could have your original driveshaft shortened the approximately 2 plus inches to fit the 8 & 3/4 or do the slip joint adapter to eliminate the B & T. Then the driveshaft would have to be shortened even more I'd consider doing the 4 speed swap at the same time and only do a driveshaft one time. Pick up a set of LBP axles from Moser for when you're ready to do the disc brake swap.

Thanks Pierre, Rock..

I was afraid of that. Seems like there's always one thing that gets in the way of these swap/upgrade deals, especially when you're trying to re-engineer something.

Perhaps a better question might have been is the 904 the same length as the 833 OD?

Unless you are swapping in an A-833OD from a truck or an A-833 from a B/E body car the A/F body gear box is the same size as the late model A-904 and A-230 gearboxes... (this also preclused the idea that mopar did some strange things late night on the assembly line and there are some Vans that did get a 'short' length manual gearbox for some reason...)

The late gear boxes also use the 'slip yoke', so you'll need to chage to that and get the slip yoke for your new gear box too...

-D.Idiot

Unless you are swapping in an A-833OD from a truck or an A-833 from a B/E body car the A/F body gear box is the same size as the late model A-904 and A-230 gearboxes... (this also preclused the idea that mopar did some strange things late night on the assembly line and there are some Vans that did get a 'short' length manual gearbox for some reason...)

The late gear boxes also use the 'slip yoke', so you'll need to change to that and get the slip yoke for your new gear box too...

-D.Idiot

Yep, looks like it's going to be easier to do all of this at once. Guess I'll just keep acquiring parts for now.

Sucks, cause the car is barely drivable right now. The brakes are woefully inadequate for city driving and the whole drive line clunks when put in gear. Hence the reasons behind all the upgrades.

Luckily the 4 speed trans. I acquired has the slip yoke.

Someone crudely hacked the prop shaft off right behind the shaft yoke. It's like a jagged, rusty beer can coming out of the trans.

The yoke itself looks like it's in good shape which I was pretty happy about. No gouges, cracks or otherwise.

well about the 15' rim thing i have small bolt pattern and i have 15' cragars on my car check out my profile for a myspace link or something to pictures but pm me if you wanna know where i got em or something i'm sure you could get a different style rim if you wanted.

Kevin

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