65mojoe

+1...that is a KILLER boss. Looks like it would give Soaring's Slayer a run for its money. Aussie and atom, thanks for the feedback.

atomsk680

i asked the guy with his camaro, he said it works fine, but he wishes he had a posi or a better locker. alot harder to park and turn with his minispool. in a few months me and him and another one of my friends are going to the track, we shall see who's is the fastest. me, my friend with his 69 camaro, or my friend wit his 74 stingray. both got 350's

Soaring

Absolutely great advice. My nephew wanted me to change out the gears in his 02 GT and I refused. I have only done it once on an old Chevy, and I will never do it again. It not only takes knowledge, it takes special tools.

72rustang

+1, as the kids are saying these days. I helped one of my friends here do an R&P swap from stock 2.73s to 3.55s in his 1988 5.0. We also installed a Powertrax locker at the same time. We did not have any of the special tools, just a dial gauge for checking gear lash. Other than that we just used the tooth marking compound, and trial and error, until the tooth contact pattern was correct. After 4 grueling days we got the thing set up correctly, but we both agreed we would probably never do this job again. Differential fluid with friction modifier has got to be one of the foulest smells on this or any other planet.

THUMPIN455

4 days is about right.. I can do them in a couple hours. A 9" in about an hour. hardest part of the 9" is getting pinion depth right and the bearing preload set. other than that, a 9" is cake for me. no spreader or fighting with an entire rear end like a 12 bolt, 8.8 or 10 bolt rear.


okay, race cars and hard core street cars CAN run a spool but there are drawbacks and things to be aware of. If you have a stock rear end with a bit of power infront of it, then swap a spool in there while using the stock axles, you are asking to break stuff.

Aussie is your rally car running stock axles? most rally cars and drag cars I know of dont. A stock axles wont take it, and that is usually the part that breaks in a full spool situation. NHRA and IHRA both REQUIRE aftermarket axles when running a full spool, and that requires C clip eliminators on 8.8" fords, 10 and 12 bolt GM rears, and anything else that uses slicks and is drag raced. once you run fast enough to require a roll bar(11.49) then you also need to eliminate the C clips and run long studs in the flanges. There is a point where aftermarket axles are required due to ET, but without a new book here I cant say exactly.

WHY does the NHRA/IHRA have these requirements? SAFETY. breaking axles, losing a rear tire, and watching it impale or knife though a crowd of spectators isnt pretty... and even if nobody is hurt, it leaves a nasty smelly mess to clean up and that takes time away from the racing.

the cross pin in a mini spool is the weak link, next is the axles. I know its tough to imagine how much stress that little 1/2" thick pin takes but it WILL break eventually. no not today while driving around in your 15 second car, but it wont last anywhere nearly as long as it would with the correct limited slip diff in it.

For a street car spend the money for the locker or the limited slip diff, you will be ahead on money and parts. having seen welded rears, mini spools, and full spools break rear end parts in the years I did my street racing, I learned to just spend the money once and be done with it. Its cheaper than doing once for $1000 than 4 or 5 times for $300-$500. (and the sheetmetal stays nicer too)

65mojoe

I was never going to buy one, just curious about the differences (and I am no 15 second car )
Thanks for the feedback though, I had no idea before about what either of them were.

72rustang

Heh. That's why next time a shop will get the work, if there is a next time. I will probably just swap the whole center section on the 72 like you mentioned earlier. Never know though, I just might get crazy, try to learn something, buy some or all of the tools, and have at it. Lots of guys here build their own engines and setting up a diff seems to me to be about the same level of complexity.

3198BullittBob

Thank you for all of your input.