8 3/4 question

[coxie1996]

i have the 7 1/4 in my 1973 charger. i was told since im doing the 8 3/4 swap that i can re use my old axles? and drums/brakes? i just need some advice as to what to swap and what to scrap.
what i know is i need:
new 3" -7" u bolts
getting new bushings
brake lines,
and misc cheaper parts.
other then these im not sure what to do. thanks guyss!

[A383Wing]

you cannot use anything...except maybe the brake & drums if they are the same size...everything else is different

Bryan

[ACUDANUT]

I agree.

[coxie1996]

is the bolt pattern atleast the same between the both?

[A383Wing]

bolt pattern for what, the wheels? If so, then yes, the bolt pattern is the same, but that does not mean the brakes & drums are interchangeable, brake & drum width come into play here as well

Bryan

[coxie1996]

so i will basically need new everything as far as seals, gaskets, and brakes for my 8 3/4? then modify my spring perches & get different u bolts? anything else?

[A383Wing]

probably a new driveshaft as well...yoke may be different size

Bryan

[coxie1996]

i have to shorten the driveshaft anyways so not a problem, & yes i was told i need a 7260-7290 combo u joint? 

[ACUDANUT]

Yep, they make a combo U-Joint for this too.

[RallyeMike]

If your car has the original rear end in it, I'm sure it is an 8-1/4, not 7-1/4. If this is the case, the entire brake set up... drums, shoes, cylinders brake lines, etc. from the 8-1/4 will bolt onto the 8-3/4 housing. 

[John_Kunkel]

No 7 1/4" in a '73 Charger.

[Cooter]

yes i was told i need a 7260-7290 combo u joint? 

Commonly referred to as a "Hybrid" U-joint.

[coxie1996]

in that case will the stock u bolts work too? im not 100% sure its not a 7 1/4. but i printed off a chart to show which is which. hopefully it will! and will the axles swap out between the 8 1/4 and 8 3/4?

[chargd72]

Never reuse U bolts. Always get a new set. 

[coxie1996]

if they are the same size im going to re use them. why spend 20-60 $ on some that will work just as good?? 

[Dino]

if they are the same size im going to re use them. why spend 20-60 $ on some that will work just as good?? 

Because the threads may have stretched from torqueing them and when they snap you're gonna have a whole lot more to spend.  When you remove the bolts and everything looks fine, threads especially, then you could get some loc tite and reuse them but I don't know if it's worth it honestly. 

Just take a good look at them before you decide.

[A383Wing]

if they are the same size im going to re use them. why spend 20-60 $ on some that will work just as good?? 

because they are gonna be stretched and weakened....you don't want that rear end coming out from under the car while driving do you? Seems the money spent on U-bolts is cheap compared to your life or someone else's

Bryan

[coxie1996]

alright guys. ill see about them. so can i use my stock 8 1/4 axles in my 8 3/4?

[chargd72]

so can i use my stock 8 1/4 axles in my 8 3/4?

No on that one too.  8 1/4 are smaller and weaker.  I believe they are 27 spline units.  The 8 3/4 is a 30 spline axle.  

[coxie1996]

i got it all figured out. i appreciate it guys!