Fellas, I have a 70' Skylark and getting to the ready for the rear end. I have the stock 10 bolt peg legger with a 2.7x gear set. I'm wanting to go with a 3.55 gear set. My question is, what are you high horsepower guys using for a rearend? Modified 10 bolt? 12 bolt? Or ford 9 inch? Any suggestions would be appreciated! Craig
Not that I should be........using a 8.5 with stk axles in 3850 pound car running g 10.90s with my iron head combo. Hoping to get enough $ after the bottom issue to get new axles b4 the season starts......we are leaving 3500 of trams brake. I can't really see after what I have done to mine on the track that there is anyway if built right one should be hurt on the street with the average street motor. Assuming it's street drive car by the gear ratio picked. Plus if using average street tires I'm pretty sure there is no way to ever get enough traction to hurt one. I wouldn't pony up for a 12bolt or 9" I'm sure even a 8.2 would be just fine in 550 to 600 hp street drive car. Again gard to really hurt one without a lot of traction
Plan is for around 500 ft.lbs. of torque. Yes street car, but will see the track. It's a 70' so i'm assuming it's got the 8.2 rear end.
Dont assume anything.... Might not be the orignal rear If it's an 8.2 bop there is aftermarket axles and posi units out there. I would build it
I would just get a 71-72 8.5” 10-bolt,and build that. Plenty of parts and gear ratios available,and you should have less into one,by the time you get your 70 8.2” built.
NEVER assume... not after 40-50 years old.... not even directly from the factory the first year...LOL. REALLY. El caminos and monte carlos in the 1970 had 12 bolt olds and tempest pontiac 10 bolt rears...THERE was a strike and they were trying to keep the line moving with what was on the line to build with. You say 500ft pounds of torque. That was a stock 455 GS engine back in the day. With is a monster amount of torque at 2800 RPM....Trouble is everyone THINKS they can do better and installs a aftermarket over durationed cam and they loose all the quick torque. BE careful on the numbers...HP is the worst of the numbers to get hooked into. If you are making a street car and want fun...Small duration and HIGH lift is what make quick fun torque. So as with anything more duration makes more HP and torque BUT it also moves UP THE rpm scale to do so...AND the reason for gears and torque converters and more compression and timing etc... IT IS THE SNOW BALL EFFECT. high 260 and low 270 cams will be some of the most torque cams in a any motor. With out changing to much other stuff on a cars components. IF you like big hole shots and skating on pavement...get a 2000-2500 stall THAT will really blister the ground. 3.08 3.42 gears and this combo will be lots of fun and drivable in all ranges. AND still give reasonable 1/4 mile time with slicks. Jim J D RAce
Rear ends.... Building the 8.25 will be very expensive...So you need to make a decisions how original you need this car to be because that would be the only reason to keep that combo. I build 12 bolt Chevy rears from Moser Housings. We can price you out a good deal on that. 9" I would just give the best deal I could from Moser and shoot you a price. NOT going to build that... Pet Peeve for me. GM in GM .... 10 bolt 8.5 you will need drive shaft shortened But I have a few housings here to build...MIGHT even have a 3.42 built ready to go with a true trac posi. Jim J D
Not concerned about keeping it OG. This is going to be a hot street car, weekend warrior. The car has a BBC in it.
Yeah, with all that extra weight of the BBC has vs what a BBB weighs, you'll definitely need a beefier rear end for sure!
8.5” 10-bolt,with 30-spline Moser axles and either a tuned Eaton unit,TruTrac,or Detroit Locker. It will take what you throw at it.
I am sort of giving up on the A9 / set 9 bearing system on those rears. Just seem to be more of a head ache than I want to deal with in my later years. I even have a disclaimer when these rears are built about the bearings and seals leaking prematurely. If the housing tubes are tweak any at all, which over 40 years you know they are...the system seems to be trouble some with leaks. Not enough room to install 7900 ends clean enough to the housings with out getting into the lower control arm brackets ... By this time the price has gotten so outrageous might as well upgrade to a 1/4" THICK TUBE HOUSING MONSTER and monster BEARING CAPS, thicker center casting... And finally finding the housing cores here is not easy anymore. Yards are scooped from china Olympics 5-7 years ago for the steel and guys are not parting out cars like they use to at swap meets. This is why I am building the NEW housings. - even with c-clip axles they will hold well to power well into the 11 sec mark. SEEMS everyone is building minimum 600HP rides which require extreme drive line parts......... Just my thoughts on the rears these days... Might be getting old... lol I pull the housing out brake clean it, paint it, build it. I still have the 10 bolt 8.5 in my Monza race car... 33 spline full spool c-clip elimed... It was an original S-10 4.3 5 speed rear. I will still build them if I find them... just not looking as hard as I use to. I will also SUPPLY ALL THE AXLES BEARING GEARS POSI UNITS YOU NEED FOR THEM... JUST PM WILL GET YOU TAKEN CARE OF. Jim J D
Jim, The most important factor is the cores. No,they are not plentiful at all anymore. If that person has access to one,or owns one,then I would suggest building it. My saying is “I can build whatever you want,as long as I have a core.” As time goes on,it is becoming more obvious to order a 12-bolt Moser housing,and build that. Notice how you see all sorts of factory 12-bolt Chevy rears popping up,but not so many buyers as there were in years past. People are beginning to realize that by the time you get that factory 12-bolt Chevy finished,to withstand your application,you could have just started with a new one,with improved design,and better geometry. I’ve done plenty of custom or one-off stuff,either for me,or for customers,to know that it is not cost-effective to do it again,or more of it to try and market it.
Yep, When I was 20 years ago I would make any rear you can think up. I sell TONS of 12 bolt camaro rears. CAn not build them fast enough. Never knew there were that many out there...lol
