New Rear End Advice

[Calif240]

Hey guys. I've got what looks to be an 8.25 rear in my 1969 charger that I'm restoring. I'm going to have to replace the diff soon and am looking at just completely upgrading to either a 8.75 or Dana-60. If I'm wanting to get to around 800HP at the rear, would I be able to achieve that with an 8-3/4 rear and higher performance axles, gears, etc? Or would I need to go ahead and go with a Dana-60? I know Moser and Strange make some nice aftermarket setups. Are there others that I should look into? I'm also thinking about getting the original Dana-60 or 8.75 case and building a new rear myself. What do you guys think?
Thanks,

[BananaDan]

I don't know if an 8 3/4" can handle 800 hp, but the Dana 60 is stronger.  With a power plant like you described I'd go Dana 60.

[68RED4SPEED]

This is the strongest third member housing  http://cgi.ebay.com/ebaymotors/8-75-8-3-4-Chrysler-Mopar-Nodular-Iron-Rearend-Case-/220779910792?pt=Motors_Car_Truck_Parts_Accessories&hash=item3367821688  if Im correct informed and that one is only good for 750 hp so I say go for a Dana 60.
Sven

[Cooter]

As long as one doesn't HOOK the car, use that 8 3/4 rear, If one actually wants to lift the left front tire about 1-2", then use the Dana 60...

[Calif240]

Thanks guys... great advice here. I appreciate the help!

[BananaDan]

As long as one doesn't HOOK the car, use that 8 3/4 rear, If one actually wants to lift the left front tire about 1-2", then use the Dana 60...

Cooter, how does 8 3/4 versus a Dana 60 determine if the car's front end will lift off the ground or not?  Wouldn't that matter more on the rear ratio than the brand of rear? 

[terrible one]

As long as one doesn't HOOK the car, use that 8 3/4 rear, If one actually wants to lift the left front tire about 1-2", then use the Dana 60...

Cooter, how does 8 3/4 versus a Dana 60 determine if the car's front end will lift off the ground or not?  Wouldn't that matter more on the rear ratio than the brand of rear? 

I think he means the difference is whether you get that 800HP to the ground or not. 8 3/4 is fine for that much power when tires will break loose before anything else, but if you arent slipping off the line and actually plant that power then th rear goes through a lot more stress and thus a Dana 60 might be best.

[BananaDan]

Ahh, I get it.  Thanks. 

[elacruze]

There's no reason not to use a D60 if you can. If you don't put slicks on it, you're in no danger with either one.

[red79]

the only reason I could think of is chassis dyno numbers--the D60 takes 15-20 or so hp more to turn than an 8-3/4. that said, for 800 hp, the D60 is a no brainer 

[heyoldguy]

I'd be interested in hearing the plan for getting 800hp to the rear wheels. Is this the Charger with the '72 340 in it?

[Calif240]

Yeah. Picked it up from Georgia last year. I've got the new floors installed and am working on body work and replacement of trim and general exterior. The interior is all replaced and ready to go in once the exterior gets some new paint. The guy before me had a '72 340 from a Duster (or so I was told). The 340 runs solid right now, but it's through a 904 and 8 1/4 rear. The general plan is to upgrade the rear first. Looking at doing that later this year. I'm planning on a new tranny for 2012 or 2013 depending on the other issues I start to uncover. Then finally, looking at doing an aluminum 440. This is all my general plan, as I'm learning a lot as I go and it seems to change each month a little bit. Any recommendations or advice that you guys can offer is much appreciated. Any thoughts on overall engine/tran/rear setups that you guys use that work well for the 700-850HP range?
Thanks guys!

[Troy]

Is it an automatic or stick? The automatic transmission isn't interchangeable between big blocks and small blocks so you need to swap both at the same time.

If you plan on racing it (sticky tires, sticky track) then you'll probably need a Dana - probably an aftermarket one that's beefier than stock. It's heavier and siphons more horsepower than an 8 3/4" but is much harder to break. It's possible that an 8 3/4" will live with and automatic and "normal" size tires since the shock loads won't be nearly as great. If your budget includes an aluminum 440 then the cost of the Dana shouldn't be an issue.

If you haven't added a roll cage I doubt if you can get 800 hp to the ground. Look in our proven combos section and in the performance corner for ideas on how to go fast. There are plenty of fast cars out there with less power. How fast do you want to go? Is 800 hp a carefully calculated number or just something that sounds cool?

Troy

[heyoldguy]

Yeah, go with the Dana 60. I'm running a 500" wedge with the 8-3/4, 696 hp to the rear wheels, 14" wide tires and a 4-speed. It's pretty good at blowing the spool and ring gear right through the bearing caps and up against the back of the housing. I built it to run in a dyno challenge and then tried to race it. Hasn't worked with the  8-3/4.

[Calif240]

Troy,
Thanks... its a console automatic. 800HP is just what I've read as a pretty good limit without getting into insane engine costs. I was talking to a local 727 race manufacturer and he mentioned that you CAN (maybe he was just trying to sell me) use the same transmission with small and big-block, but need to change the bell-housing and a few other small things ($300 was his estimate for the change). I'm expecting the aluminum 440 to be $4k-5k for the block and then of course the other components. I've read a few nice engine setups that reach around 750 and are still at 11.5 compression. The end goal is to lighten up the front so that it handles just a little bit better, put a new hotchkis or O'Reilly suspenion up front and a 4-link in the rear. (Still researching this one). I want the car to come off the line fast... I'm thinking that under 10 seconds is achievable, but don't need to go much past that. I would like the car to appear pretty stock from a distance, but have some nasty new technology in suspension, aspiration/Fuel Inj, etc. I'll check out some of the proven combos. I've got a book on MOPAR big block combos that has been helpful thus far. I appreciate your suggestions. Let me know if you have any further. As I say, you guys know a hell of a lot more about this. I'm a novice and trying to learn as much as a can.
Thanks,
Terry

[Troy]

The bellhousing is built into the case on a 727 so the conversion requires either a new case (internals are the same I believe) or cutting off the front portion and replacing it. For $300 he's probably just swapping cases.

You'll need a cage to break into the 9s (mandatory I believe). Honestly, I think it's perfectly reasonable to get into the 9s with an iron block and basic suspension components. You'll want to put the whole car on a diet as well. I love new technology but it's not necessary to meet the goals you've outlined. If you just want the "Wow factor" then that's possible too - just very expensive.

Troy

[Calif240]

What would be a general HP range you'd recommend for a charger to be under 10 seconds? What other major changes would help it handle better besides suspension? I'm only looking at an Aluminum 440 because of the weight savings and knowing how much the B-Bodies are nose-heavy, figured this was the easiest way to shave pounds (in addition to new hood and a few other lighter components). Maybe I can do this all with a regular 440? Any other recommended sources for a build like this? I really appreciate your help! I'll try to include some pics once I get the paint on it.
Thanks,
Terry

[Troy]

All right, first things first. What are your end goals for the car? Street driven or race car? It doesn't sound like a "restoration" at this point. If you're putting all new interior and trim in it you're wasting money if you're going to race it a lot. Same for any body work on the fenders/hood.

Secondly, have you ever been in a car that runs 10s or faster? I ask because I had a roommate once who wanted a sub-12 second Civic. After some prodding I found out he'd never been in a "fast" car so I got him a ride in my cousin's 11 second Challenger. He was excited and awe-struck afterward but he decided (correctly) that a 14-15 second car would be fine on the street. If you want to street drive you need to realize that race parts are finicky and finely tuned (mostly) race car can be a painful experience on the street (steep gears, lumpy cam, high stall converter, overheating, uncomfortable seats, poor steering, tires that wear within a few thousand miles, etc.).

There's a formula for converting power to E.T./speed (and vice versa). If you want to build a race car I'll move this thread to the performance corner where you'll get better answers from the performance oriented members. Race sanctioning bodies make the rules for what safety equipment is required. Again, the guys who race will be able to give you better guidance than me.

Troy

[Calif240]

I definitely want to be able to drive it on the street. I consider it more street than strip. What I consider #1 priority is that the car "looks" pretty stock. So no blower out of the hood, etc. However, I'd like to be able to take it out on the strip and make some noise and beat new SS camaros and Mustang Cobras that are tuned up. Unfortunately, I know I'm asking for my cake and wanting to eat it too when you want a driveable racer. However, I just want to get something that has a really nice punch, handles well, but still has those beautiful curves and lines of the 1969 charger. I've not been in a 10s or faster car. I've been in a 12s Cobra. If I have to settle for 12s to still be street-worthy, then I'm ok with that. But I'm willing to spend some extra to keep the 1969 Charger street-legal and driveable, but have a nasty punch. I'm ok with you moving this thread and really appreciate you and everyone else's help.
Thanks,
Terry