Hello, been told not to ever do a rear end gear unless you are trained you will wear or have shimming mistakes. have a Skyhawk 79, with a believed to be 3.42 rear, cant drive on hwy, motor rev's too high for buick engine. Want to put in like a 2.89 or 2.74, for hwy drive enjoyable. Present is a 3.8 switching to a buick 350 block, and is run on a 4 speed manual, present time 1st gear is a total waist. 1st good to about 12mph, can start in 2nd and 4th drops in at 35mph to 55mph with a 3500 rpm aprox. 62-65 4000+rpm . Would like to drive a 65 doing 1800-1900 tops in 4th. for travel to shows. Need milage I am burning too much gas, and is doing damage to drive train in too high a rev. What is available? numbers, recommendations welcome. Posi diff would be nice , does later 82-92 camaro posi fit this rear? maybe S10? etc. Do I really need help putting in gears in shim? HELP please , all welcome to kick in. , craig Never done a rear end
If you want it done fast and right then have someone with experience do it. If you have time and dont mind doing a lot of trial and error then it can be done yourself if youre mechanically inclined and have access to the right tools. Changing gear ratios involves changing out the pinion gear which then requires that you properly set the pinion depth of the new gearset. A pinion depth checking tool will make it easiest. It can Also be done by using the original shim to get close then checking pattern etc. but its a lot of repetition until you get it right. Get in touch with Jim at JD Race and Restoration. He is the guy to go to for the parts etc that you need. He is a ton of help too. PS sounds like you are about right on the ratios you "like". hi 2s will do you well
Can't buy off the shelf parts for that rear end. just went through this in a Vega call Jim a k a monzaz
just found a diff on ebay 399, name brand, and gears at summit 2.73 new , hoping the saginaw will bolt to v8 buick bell if need to use. or if 13.375 inch buick flywheel will fit in old bell off v6 or if I have to use v8 bell. then will 4spd saginaw bolt up. ????
just found a diff on ebay 399, name brand, and gears at summit 2.73 new , hoping the saginaw will bolt to v8 buick bell if need to use. or if 13.375 inch buick flywheel will fit in old bell off v6 or if I have to use v8 bell. then will 4spd saginaw bolt up. ????
Those gears won't work. trust me call Jim at j d race . i bought 2 ring and pinion before i called him and he laughed and explained to me why it didn't work. will never buy rear end parts any where else he sent me loads of extra stuff i didn't even pay for but needed and the grease he sent to check pattern was the best I've ever used. he is very knowledgeable to.
Skyhawk or skylark? Do not guess on the ratio. Open the rear and check it...THEN pick your gear. MOST never came with that much gear. 3.08 was performance ratio for those cars... 2.56 2.29 2.93 are common h-body ratios. I have a few sets of 2.56 ratios on the shelf if you want to try that ratio... BUT first see what ratio you have. If the ratio is less than you think 3.08 then going to 2.73 will not be enough. I can machine any ratio you want new or used. H-body 7.5 pinion shaft is 1.376 with a 25 spline yoke all other 7.5 pinion shafts are 1.438 with a 27 spline yoke Everything else is the same. Check that ratio first. Jim J D
A 3.42 gear will be about 2700 RPM at 60 MPH. Either you are guessing at the RPM, or you have a lot more gear than you think.
SKYHAWK ROADHAWK performance pkg Y43, possible 410 rear. car goes 60-65 at 3800-4000 rpm, first is worthless. 3rd should be 2nd gear, always feel like wish had a 5 speed at 50 want to shift up.
Nope, that still doesn't make sense. With a 4 speed car, there should be no slippage unless the clutch is toast. 336/tire diameter X rear gear X MPH = RPM. With a 26.6" tire, and 4.10 gears, I get 3366 RPM at 65 MPH.
if your handy With a welder and angles it might be better to build a trans am 8.5 and 4 link the back. i will never do another 7.5. head ache
I did 11.90 with a STOCK monza rearend 3.73 gears - 2500 stall alot of cam... Your fine. REMEMBER guys the h-body skyhawk can only fit 25" tire max in the wheel well. 24" tall tire is NORMAL for this car. NOW figure the 3.42 gears and rpm Larry. Jim
Jim, Even with a 24" tire, and 3.42's, 65 MPH is 3112 RPM. 4.10's and a 24" tire gives 3731 RPM at 65 MPH.. So maybe he has 4.10's
im not Worried about the 7.5 strength as much as i had to buy numerous ring and pinion before i consulted an expert. (Monzaz) then it Was easy. finally got the axles in today. had to take brakes wheel cylinders and knock wheel seals in like you said. took me 1 day to build my 8.5 its been 3 months for the 7.5. can't get long wheel studs that fit either had to use a ford .5 inch wheel stud. .480 to small. had to have machine shop install studs. extra 80. then at the end of all the buying bearing kit then having to buy extra pinion bearing and race. you still have an 7.5
Summit has long metric studs...That is what I have on the race Monza as it still has STOCK GM axles...LOL. Will see how they do on the next 400 motor. Jim
Bearing kit could have been purchased correct too 1st time if you bought from a diff shop . IF we had the project from the beginning it would have been MUCH smoother. lol. Jim
Just did this one for a guy in KAnsas I think...any way Moser axles 28 spline mini spool 3.73 full brake package..
