8 1/4 Sure grip ??

[Zoidburg]

So i've been looking through posts for hours now looking for all the information I need to swap out my 8 1/4 rear for a 8 3/4 or 9 1/4 rear end.  I keep seing posts of an 8 1/4 "posi" or sure grip.  Do these exist or are these people full of it?  I looked for gears or guts to buy and no luck.  I have a 73 charger with a 250ish hp engine and I want more traction.  Any help would be great.  Thanks 
  Z

[RallyeMike]

Yes they made factory 8-1/4 sure grips. Check out Randy's Ring and Pinion for new parts. It is expensive.

[64dartgt]

I was in the same boat last year.  Called a local rear end rebuilder which advised me not to waste any money on an 8.75.  I found a sure track 8.75 used for $400 and had it rebuit with 3.55's, new green bearings and new clutches for about $1500.  Turns out that I likely could have gotten a core through them.  People offer them cores all the time, but they don't take them due to lack of storage.  You may wish to try calling a local rebuilder and seeing if they can source one for you.  Alternately, you can get a new complete axle from Moser for ~$2.5K.

[Zoidburg]

I think you are saying not to waste my time on the 8.25 not sure if that was a typo.  Was curious if I would just be able to pull the guts outta mine and replace it with the other guts.  I just had the springs on the back redone so the bolts should come out fairly easily.  Im just not sure how hard it would be to find an 8 3/4 for my application without making to many modifications.  Its a 73 and sounds like a bit of a pain.

[Cooter]

Sure they built 8 1/4 Sure Grips..Would I advise running one? Nope, not when there's 8 3/4's out there. You WILL break the 8 1/4" rear with a healthy small block, a Big block with destroy one.

[64dartgt]

Actually 8.75 are relatively easy to find for a B-body.  They are a nightmare to find for an A-body and you usually end up shortening a larger one and moving the perches.  Keep in mind that it is tough to do this cheaply.  Finding an 8.75 WITH sure grip WITH the exact ratio you want in a package deal is tough and you will still pay good money for it.  I found mine for $400.  I could have run it as is, with clean up (wire brush and paint) with its 3.90 gears.  The sure grip was worn.  The backing plates were the same size (not always the case) so all my 8.25 brake stuff 9which was new) swapped right over.  You would have to change the U-bolts too (~$60).

[Cooter]

I got Two 8 3/4's for an A-body...Haven't had any bites yet...

[64dartgt]

Details and how much?  Sorry, but I couldn't find the post with search.

[John_Kunkel]

I don't thing the 8 1/4" is as whimpy as many think it is, I'd run one with a mild small block.

Unlike the 8 3/4", the 8 1/4" limited slip units are ratio specific so be careful when buying one that it'll work with your gears.

[RallyeMike]

Agreed.

Its a mind set. People automatically think you have to have the 8-3/4 or Dana. The 8-1/4 is fine in the correct application, and is a fine choice for a street car. If you are going to redo everything, then I would find an 8-3/4. They can be found for $100. That way you will be set if you ever decide to put down more power.

Chrysler originally put 8-1/4 axles behind big block 2bbl engines. I ran one behind a 440 in the road race car for 3 years because I needed the 2.45 gears available in the 8-1/4. I'd still be running it today if I hadn't done a major drivetrain swap to go faster.