gm 7.5 rearend for g / str

[Stan Back]

No F in StR.

[mitchell968]

nothing gets past you guys.

[Frankie7799]

Question when it comes to the HP you all are mentioning. WHen you say x hp, are you talking at the flywheel or at the rear wheels? Desoto man mentioned the motor in his str not making one hp per cu and yet it ran pretty well at el mo. My 394 SBC that I had in my dragster made 625 at the flywheel. Just makes me curious what a similar motor would run in a 2600 lb str such as Desotos. Obviously that would fall in the B category and at the small end of the range so it wouldnt be knocking on the door of any records. Not trying to hijack the thread Mitch, was just reading along and wasnt sure how you all were figurung hp. 

[SPARKY]

M968  as others on the list will testify---I am not very concerend about how things look---lol

[desotoman]

Question when it comes to the HP you all are mentioning. WHen you say x hp, are you talking at the flywheel or at the rear wheels? Desoto man mentioned the motor in his str not making one hp per cu and yet it ran pretty well at el mo. My 394 SBC that I had in my dragster made 625 at the flywheel. Just makes me curious what a similar motor would run in a 2600 lb str such as Desotos. Obviously that would fall in the B category and at the small end of the range so it wouldnt be knocking on the door of any records. Not trying to hijack the thread Mitch, was just reading along and wasnt sure how you all were figurung hp. 

Frankie,

Lets just say my motor made one HP per inch at the flywheel (350hp), with your motor it should go approx 197 in my car.

Tom G.

[Frankie7799]

Frankie,

Lets just say my motor made one HP per inch at the flywheel (350hp), with your motor it should go approx 197 in my car.

Tom G.

Tom, I meant to say more than one HP per inch not less sorry, wasnt trying to knock the motor you had. Its good to know what a motor like I had would do in a STR if I decide to go that route. Is that approx 197 at El Mo or the salt?

Frankie

[desotoman]

Tom, I meant to say more than one HP per inch not less sorry, wasnt trying to knock the motor you had. Its good to know what a motor like I had would do in a STR if I decide to go that route. Is that approx 197 at El Mo or the salt?

Frankie

Frankie,

Don't worry about it, my motor was a piece of junk, cast crank, stock rods, two bolt mains, etc. Just wanted to see what I could do with it. El Mirage is the answer to your question.

Tom G.

[CTX-SLPR]

Howdy,

have a technical question to ask about running the 7.5in 10-bolt rear at Bonneville.  I'm still waiting on my rule book but going off of the checklist in the rookie guide, I need positively retained axles.  What is the common/recommended way to do this on the 7.5in 10-bolt?  I saw Ford 8in axles and ends listed, is this a cheaper way than the more common 9in housing ends and custom axles?

Thanks,

[SPARKY]

look weird---go fast---put the smallest tires you can that fit the rules---cant go below15" wheels

[CTX-SLPR]

look weird---go fast---put the smallest tires you can that fit the rules---cant go below15" wheels

Not sure I'm following you there, though it is good to know I can't run the stock 14in wheels.  Need to find some 15in steelies.

I thought it would be best to run taller tires to compensate for less than optimal gear availability and the fact the engine I'm planning on using won't rpm over 6000rpm.

[SPARKY]

he was in roadster  minimum 15" wheels  the little GM 7.5 has the greatest selection of ratios for LSR  you are going to have to put C-clip eliminators in any way!!  change!!!

[CTX-SLPR]

he was in roadster  minimum 15" wheels  the little GM 7.5 has the greatest selection of ratios for LSR  you are going to have to put C-clip eliminators in any way!!  change!!!

Do ya'll tend to use the bolt on ones that go on the housing ends and use the stock axles or are you talking a full blown housing end change with new axles and a Ford 8/9in bearing?

My appologies for the hijack off of the orginal question but I thought it was best to put it in the same thread since it's titled with the axle itself.

Thanks,

[maguromic]

he was in roadster  minimum 15" wheels 

"The minimum wheel diameter for all Vintage Category vehicles with the exception of / VOT is 14 in ". - page 54, 2012 rule book -  Tony

[SPARKY]

Thanks for the catch Tony

[overdue]

GM 7.5" fact corrections:
Ratios mass-produced:
2.294:1, 2.412:1, 2.5625:1, 2.733:1, 2.929:1, 3.077:1, 3.231:1, 3.417:1, 3.727:1, aftermarket 3.909:1, 4.10:1, 4.30:1, 4.556:1
There were a few aftermarket 3.546:1 sets. Happy hunting for those.
 HP capacity: around 500, fully built. Forget a 900-horse anything unless there's NO traction. In which case why have 900 horses?
With stock 28-spline axles, or aftermarket 26-spline axles, the weak link is typically the R&P, even with a girdle, though I've failed the differential cross pin, behind a 170-horse 305 with an automatic transmission. May have been a defective pin.
 '85-up were 7.625" ring gear, possibly excepting S-10 / Astro, which easily fits all 7.5" cases. 28-spline shafts appeared in Camaro / Firebird, even V6/auto, in mid '89 or mid '90, I forget which. Probably '90.
 S-10 starts narrowest overall, '93-'02 'maro / 'bird is widest. All '82-'02 'maro / 'bird versions used a torque arm, all Malibu / Monte / Cutlass / Regal / Grand Prix used a triangulated 4-link, all others were leaf springs.