I checked the RPO codes of my 'maro the other day and found the rearend options. I should have a Posi diff. with 3.08 gears.

At work yesterday, I pulled the diff cover to check it out and found an open diff. with 3.42 gears...

I am not all that conserned since I plan to rebuild the rear entirely anyway, I just think its odd.

How do you all out there feel about the 7.5" rearend? I want to change to an Auburn posi and 3.73s. I might change axles but am not sure. What does everyone think?

 

the 10 bolts is ok..but in stock form, from what i have learned, it has room for improvement.

yours is actually a 7.625" 10-bolt, which is better than the earler ones.

not sure exactly what your question is, but if you want to make it a lot stronger than it is now...you need a new differential, good gears, and an aluminum cover. also, a lot of people get the axle tubes welded to the pumpkin. you should also have 28-spline axles, which are better than the earlier ones. if you have the money, you may want to invest in some new axles, but it all depends on what you plan on doing.

how much power do you plan on having? are you running slicks? how fast do you expect the car to go in the 1/4" and 60' time?

-Brian

 

Thanks for repling.

My question was just how others feel about a beefed up 3rd Gen rear end. I am going to run low 12s- high 11s on motor, shooting for 10s on 'charger (when I get it tuned). I do eventually plan on getting a 12 bolt or 9 inch, but until then I want to upgrade what I have. For now I have drag radial, but when I hit the strip I may get some real slicks.

You say I have the 7.625. How can I tell for sure? I don't doubt you, I doubt the car. Like I posted earlier, it does NOT have what the RPO codes say it should have. I am planning on doing the rearend work in about late July/August.

I figured on the diff, gears, and cover, as well as new bearings and seals. You think axles too? What company makes good ones that won't break the bank. My old race car had Moser axles that set me back almost $700. I don't want to get too out of control with this thing.

THanks in advance.

 

Judging by the hardware you listed in your sig, any money spent on upgrading your 7.5/7.65 10 bolt would be a waste. I would be surprised if you're are making any less than 425 lb/ft of torque. Hook up that kind of torque with drag slicks and it's SEE YA, not at the finish line but on the trailer. I want to say the limit is around 350 lb/ft at most for a well built unit. In my opinion you should consider upgrading to a 12 bolt or 9 inch before making more power.

 

THanks for your thoughts

I am GOING to upgrade to a 12 bolt or 9 inch someday. I don't have a blower yet, but I am saving and planning on it being my christmas present to myself!!

I have been thinking that any money spent will be wasted, but I need to do something. The seals are leaking at the axles and the pinion. I assume there is a seal at the pinion because there is some oil on the exhaust pipe and the floorboards around the front of the rearend housing.

Anyways I have roughly figured about $1100 for parts to upgrade my rearend. Priced through a Jegs catalog. Not the best prices in the world but an idea. I think a 12 bolt setup for me is about $2200. I don't know. If my stocker will last for few years, then I would not hesitate to build it up. If it is going to blow up after a few hard launches then I won't even deal with it.

New question:

WHO HAS THE MOST POWER AND FASTEST CAR WITH A 3RD GEN REAR END?

 

I'm not the fastest on a completely stock rear end, but high 11's/low 12's with 1.72-1.75 60 fts on a stock 9 bolt. This is behind my 500hp/520lbft big block. Been running for over 4 years now.

Miles

 

Thanks, thats good to know!! Do you launch it pretty hard? Got slicks? Just curious.

 

Dont waste your money and time on the rear. Save up for the 9" Moser and run yours until it dies. Just my 2 cents. I did something similar with my 9bolt BW....it did not die I sold it.

 

Thanks for your input. I am still debating though!! Its a tough call to make. I don't want to waste my money on a stock rearend that will be swapped eventually, but I don't want to have to spend so much right now!! Maybe I'll just flip a coin...

 

I would just replace your seals and while your in there check out the gears, if you need new ones pick up some lower gears from a yard....i think the 87 GMC Jimmy's have 3.42 or 3.73 with posi.


gl


-blain

 

I have 3.42s now. Just no posi. If I decide to change the pinion seal then I will put in a posi. I could check out the yard for that. Maybe an SLP take off unit. Will that fit? Any ways thanks for the input.

 

Thanks again for all the advice and comments. I decided to go ahead with the SLP torsen diff. Its only $100 so if it doesn't last that long I am not out much. In the mean time I can have posi and save for a 12 bolt or 9". Now I have to decide which one!!

 

9" is the best...hands down it will withstand high horsepower and a blower - it will be the last one you buy. My opinion guys so dont jump down my throat.

 

If you want to spend some money on your 10bolt I would recommend the differential support cover. 10 bolts have a weak case. The support will make a difference in how long it stays together. Also if you pull the pinion replace the crush sleeve with a Ratech solid spacer and shims. I bought both items from Summit.