rear end ?'s

[ddjayl]

Hello all. I have a couple G body rear questions. My 83 Regal Limited has a 7.5" open rear. I'm wondering how to determine the gear ratio. Is there a code somewhere on the rear, if so a tag or stamped? Seems to me it was supposed to be on the front of the right axle tube, but I can't see it.
Also, I'm planning on putting in a set of 3.08's and a posi. I was thinking of putting in a Detroit Truetrac. Does anyone have any experience with this diff. Do you prefer Auburn, regular Detroit Locker, etc? Thanks!!!

 

[bowtie81]

well you could put a mark on the tire and one on the drive shaft count how many times the drive shaft turns to 1 tire rotation, that will give you a rough idea. one of the other guys on here should be able to tell you how to look at the part numbers.

 

[megaladon6]

after a bunch of research (but no money to buy anything yet) the true-trac is pretty good for street handling. the auburn is a pretty good one, but can obviously wear out and for sharp tight turns it doesn't "uncouple" as much as the true-trac.
there are some mods that can be done to the t-t to make it much better, there are also better diff's for not much more money if you're gonna be racing. go to pro-touring and talk to chicane67.
lockers? they're really for the drag strip. there are some that can be used on the street but won't come near the handling of a good LSD.
however, there's no point to spending the money on one for a 7.5in rear. i'd get an 8.5in first, then mod that. with a little luck you could get one with 3.42 (great with a 200r4, not great with a th350) gears and a posi from the factory.

 

[81_2dr_bu]

just curious i have a 3:42 8.5" with a th350 and wonder why you say its not good with a th350 my car is street use with a 383 and the 3:42 seem ok to me but i plan on going to 390's i also have a buddy with a 78 bu 454 with 390's and a th350 and is a street/track car i am a novice thats y i ask i figured the 8.5 is stronger and is overall better than a stock malibu 7.5 rear

 

[megaladon6]

how many RPM's are you turning at 70mph? i'm guessing about 3k, not where i'd want to keep the engine on a road trip. i'd much rather have the 2k or less of overdrive.

 

[81_2dr_bu]

the light went on when i was reading i do mostly city driving i have thought about the 200r4 and 700r4 install for the o/d i had a post dicussing my h/p and trq and the info i got was they might not hold up cant remember if they were speaking in racing realm i dont race mine or beat on it i lean into it at cruise speed but havent done any burnouts etc

 

[megaladon6]

both the 200r4 and the 700 had problems when the first came out. a lot of it was due to people adjusting the TV cable improperly, but there were weak parts put in also, especially on the 700r4. however the weak areas have been identified and can be fixed. they've been built up to take 800hp on a drag car! i'm sure that they'll hold up to yours.

 

[81_2dr_bu]

good to know i will keep that in mind for the future thanks