1970 dodge coronet small block 904 trans,ok almost ready to hit the road, but ran into another snag-go figure. Put new u-joints in my driveshaft before installing it. When I went to put it in the rear u-joint was to skinny like the two little clamps that bolt the back in would barely even grab the caps of the u-joint, I know this is hard without a picture but it isnt the round part of the cap that is to thin its like the length of the cap is to short. the u-joint is the same part number for front and rear is that right or should the rear be different? I did swap rear ends from I think a 8.25, to a 741 8.75 out of a 70 roadrunner. then length looks ok. HELP-I have brand new tires and I hate brand new tires hehehe:driving:

 

It sounds like you have a large U joint flange on your rear end.. Easiest way, not the best way is to use a conversion U joint

 

Can I just take the small flange off what I am pretty sure is a 8.25?

 

I never heard of a conversion u-joint where do you get one and will it hold up to abuse-I have big tires and plan on putting lots of miles on while sitting still

 

Something like this: http://www.dennysdriveshaft.com/p198...reaseable.html

Many manufacturers make them and can be found at common auto supply.

My shop manual says driveshaft exact same length for those two rear ends. Wish I could scan to give a picture of trans linkage.

 

Looks good but before I mess with buying a new one anyone new if I can just pull the flange off my old rear end?

 

This should answer: http://www.dennysdriveshaft.com/c88_pinion_yokes.html

 

If your drive line is all the small u joints (7260) then using a conversion ujoint (7260 to 7290) will not make your driveline any weaker. I've used one before with that same circumstance. I'm not 100% sure but I'm gunna say no the yolk from the 8 1/4 will not work on the 8 3/4. Good luck on your project.

 

7260 and 7290 were the common Dodge sizes but now there are aftermarket size yokes availible that allow you to use 1350 size u-joints. That what I run with my 440 Dart. Here's a link that tell you how to measure them. Look at the 1350 size compared to 7260 and 7290.

http://www.driveshaftspecialist.com/...D%20Guide.html

 

I had the same thing happen to me... Installed a posi 3rd member with the large companion flange and my driveshaft was for the small. I pondered changing the flange and then found out that I was fortunate enough to have a correct driveshaft on hand from the car we took apart.

If it were me, in your situation, I would use the U-Joint that makes your driveshaft work.... and leave the 3rd member alone.

You will be back on the road in under an hour!

 

I agree a trip to even Autozone will work, used that style of joint in my old circle track car and never had a failure. Used to call em 'bastard' ujoints as a slang term.... Very common..

 

Talked to the local o'reilly and advanced auto stores today they both say they are working on it for me but no luck as of so far. Hopefully I can just get one from them vs. ordering one off the internet, gonna be gone for the weekend so if they dont have anything on Monday I will have to look at ordering one online.

 

I would order via phone call from Randy's Ring and Pinion, Denny's Driveshafts or Doctor Differential. They will tell you how to measure and determine which size you need.

 

well I cheaped out-sure I'm gonna pay for it later, I gave my specs to autozone advance auto and o"rielly and autozone came out on top with a moog ujoint that they stole the caps off another joint to make it work, they damaged the one they took the caps off for mine so the store would get credit and charged me $10.50! it didnt fit perfect I haad to file the inside of the driveshaft lobs down so I could get the clips in but as of right now its in the car-first test drive is tomorrow just have to add diff fluid and check everything over and its ready to go!

 

Watch out for sparks in the rear window.

 

Sorry this might be to late, I just picked one up for my truck. I gave the parts person a Dana Spicer 5-527X number he crossed to an AC Delco 45U0169 number, fits perfect. Don't listen to them when they say it won't fit a Dodge.

 

I put about 100 miles on it so far and wow am I having a hard time with being nice to the new motor, it revs extremly fast with the stall and the 3:91 gears, jumped on it twice for about a second and the 295/45/18's didnt stand a chance instantly sideways

 

Yahoo! Good job.