Hey guys, I currently have a 1971 Grabber with the 14" wheels on it. I just got a new 347 stroker kit, and now need to look at my rear end. It is of course the 8". Now, with my mildly built 302 and 3.00 gears it did good. Never broke or anything, and I was hard on it. (wink wink)....but now w/ this new stoker kit, cam, headers, and stall converter I have at home, I am afraid from all the posts that it may break. I don't want to go with a 9" because of weight, and costs. I checked out the bolt in and go Alumin8 from currie, but that whole kit was something like 1500 bucks. I only have 400 or so to spend on this. I am looking for a posi i guess, since a detroit locker would be too impractical for my weekend crusier and every now and again dragstrip run. Or would it? see..... i dunno. I need help guys... i'm close to getting it back on the road. How much HP, or torque i should say, will the 8" hold (stock). and could i just get a new ring and pinion and a posi unit to work? Also, difference in times between the 3.55 and the 3.23*(probably not correct ratio) how much harder would my car run at say 60mph between a 3.55 and a comparable 3.23 or so. or heck, even say my 3.00... any and all info greatly appreciated guys. Thanks. and see you guys at the shows.
checkout this calculator to help answer your question: http://bbs.hardcore50.com/calc/?mode=rpmforspeed
Where is Botetourt, Virginia? Is that close to Dulles, Virginia / Washington D.C.? Hopefully see YOU and your car at the 14th Annual MCCI Roundup Nationals July 24-29. Find out more at: www.maverickcometclub.org
An 8" ain't gonna last behind a 347. I couldn't get one to live behind my 306s. You could get all the trick 8" parts and make it slightly stronger, but you will spend the same money building up a 9" that will be significantly stronger. Do some research... If you use a regular 9" housing, your 8" brakes, stock axles, and one of the stock cases, you only add about 8 lbs over an 8" rear! HD housings, big brakes, aftermarket cases, HD 31 spline axles, and such things are what adds extra weight. Even then, it isn't as much as you would think.
Not to mention you wouldn't miss any gears and both front wheels would come off the ground instead of just the right front.
W/ an automatic I've seen 8"s live in 11 sec cars.Put in a good locker unit and some aftermarket axles & you should be fine.
Axles are not the weak spot in 8" rears. We have 28 spline 9" axles. They can break, of course, but usually never in an 8" because the center parts are so much weaker. Therefore, buying aftermarket axles for an 8" would be a waste IMO. Also, the weak parts in an 8" cost more to replace aftermarket than stronger stock 9" parts. So it's almost a matter of spending more to have a weaker rear when trying to build up an 8". The costs, combined with multiple broken 8" rears, are why I just say 9" when these posts pop up. Unless the 8" option is just a no-brainer because someone has an I6 or stock v8. Dave Edit: I feel the need to summarize. I don't think I was very clear. An 8" can be built to handle massive HP, but at what cost. Build a 9" for that same HP, and it will be same, or more likely cheaper. So build an 8" if you want.
Note to self - Once again I find myself scratching Ray off the Christmas card list, buddy list, and all-around nice guy list. For the first time, I am adding and then scratching Dave's name from those lists as well. Of course, this might be a more permanent solution -
according to that link, i am going to run out of engine at the 1/4 stripe with 26.1" tires at 96 mph if i go with a 27" tire, then i can run at 103 mph before i run out of engine so the gears i got would be great..but not on my current engine.. hmm..i think i need to upgrade my intake and valve springs before too long.
remembering that the calculator is based on "perfect" set-up or close to optimum and has a disclaimer of (+-) 5%.
