8 3/4 rear in 65 Signet

[Gib Warnick]

I looking for info on what I am going to need to swap my stock 7 1/4 with an a-body 8 3/4 rear into my '65 Signet. I have a complete a-body-if I remember right, I'll need to locate u-bolts for the 8 3/4-longer than my 7 1/4 rear? I have a 741 center pumpkin now-will using that make the yoke solution easier? I know I'll have to get the dirveshaft shortened-right? Any info on yoke to use and rear universal to be used? I have a 741 center pumpkin-Ok to use for street car with street tires-or look for 742-489? I understand I can keep the old style front universal...? I have 2.25X70 14 inch radials-any recomendations for gear ratio-leaning toward 3.91s or maybe something in 3.70 range. I will be replacing the 273 with a warmed over 340 and will use car mostly for local cruising (and burnouts!). apprecitate your thoughts-especially if someone has gone through a similar process lately. Thanks guys.

 

[66340SEDAN]

8 3/4 rear parts you will need: shock plates, u-bolts, shortened drive shaft.
Use the brakes from the rear too. The 741 rear will be fine, I have one on my 1974 Satellite with a 340 engine, my buddy also has one on his 1970 Coronet with a 440. Your rear probably has the small joint size, that will also be fine. If it has the larger size, you can get a joint with both sized ends so you won't have to change the yoke. I would recommend heavier duty leafs, or maybe just have them add a leaf and have them re-sprung or arched. Your old brake lines and shocks should work too. Good luck!

 

['64 Cuda]

I don't know what year 8 3/4 you have. When I put a '71 8 3/4 into my '64 I had to reuse the parking brake cables from the old 7 1/4 rear axle. They swapped right onto the new brakes with no problems. The reason for new U bolts is because the new axle tubes are 3" (I think) in diameter & the old ones are smaller. I also have a 741 center & have never had a problem with it. The entire swap is pretty easy. Biggest hurdle is shortening the driveshaft, 2 1/4 inches if I remember right.

 

[dartcuda]

As others have stated you will need to shorten your drive shat, plus you will need the shock plates for a 8 3/4 and the u bolts. Another thing to keep in mind is the bolt patern for your wheels. 65 had the small 5. Now depending on what year the 8 3/4 is your bolt pattern might be the 4 1/2 on 5. I believe up to 73 are the small bolt pattern. This might also help you out.

 

[Gib Warnick]

8 3/4 rear parts you will need: shock plates, u-bolts, shortened drive shaft.
Use the brakes from the rear too. The 741 rear will be fine, I have one on my 1974 Satellite with a 340 engine, my buddy also has one on his 1970 Coronet with a 440. Your rear probably has the small joint size, that will also be fine. If it has the larger size, you can get a joint with both sized ends so you won't have to change the yoke. I would recommend heavier duty leafs, or maybe just have them add a leaf and have them re-sprung or arched. Your old brake lines and shocks should work too. Good luck!

Thanks for info 66340sedan- you mentioned that a u-joint is available to match up different sized driveshaft and yoke sizes. Do you know who has them available?

 

[Gib Warnick]

[QUOTE='64 Cuda]I don't know what year 8 3/4 you have. When I put a '71 8 3/4 into my '64 I had to reuse the parking brake cables from the old 7 1/4 rear axle. They swapped right onto the new brakes with no problems. The reason for new U bolts is because the new axle tubes are 3" (I think) in diameter & the old ones are smaller. I also have a 741 center & have never had a problem with it. The entire swap is pretty easy. Biggest hurdle is shortening the driveshaft, 2 1/4 inches if I remember right.[/QUOTE]
Thanks for info '64 Cuda- especially about the parking brake cables. That's the kind of info guys on this board can help with-having been there before. My axles are 4' bc but thanks for mentioning the possibility. And your memory about shorting by 2 1/4 is right on the money by the chart dartcuda gave us. Thanks again

 

[Gib Warnick]

As others have stated you will need to shorten your drive shat, plus you will need the shock plates for a 8 3/4 and the u bolts. Another thing to keep in mind is the bolt patern for your wheels. 65 had the small 5. Now depending on what year the 8 3/4 is your bolt pattern might be the 4 1/2 on 5. I believe up to 73 are the small bolt pattern. This might also help you out.

Thanks for the chart from moparstyle-I printed it out to keep for future reference. It shows that 2.26 is right on the omey for driveshaft-though I know an individaul car might be different a little.
Anyone know if less ratios are avialable for the 741 rear? Several ads sho the for 742 and 489 but not 741>

 

[66340SEDAN]

I got mine at Auto Value. I think most stores might have them, a drive line shop would have them for sure. I have a joint in my Dart that has a large end and a small end, it works great. I switched it from a 741 to a 489 so I could use some different gears. Then you don't have to switch the yokes. Just ask for a u-joint that has the large and the small size. If you can't find one let me know, I could get one for you, Keith. :thumbup:

 

['64 Cuda]

I have a couple of catalogs, Randy's Ring & Pinion & Reider's Racing, & I don't think either one lists anything for the 741. I just found my Yukon Gear catalog & they list a 3.55 & a 3.73 for the 741 case. I don't know what the factory offered but mine has a factory 3.91 Sure Grip. Don't know what it came out of, my local salvage yard found it for me & had it shipped in by bus back in 1975 or 1976. I think I paid $90 at the time. Think I can find another for that price? I'll take two. :thumbup:

:burnout: