Came across this thread, Has anyone ever tried this ? QUESTION : ....I have an instruction guide to put a SBF in a Ford Pinto and it talks alot about the Ford 8",8.8",and 9" rear ends.It mentions something about making the rear end a posi without buying a locker.Here's exactly what it says: "Simply add an additional spider gear side shim to each side of the differential carrier housing and bolt the carrier halves back together." Anyone comprehend that?If you could,tell me if that would work and what I'd need to get to do it. ANSWER :.... Under each spider gear inside the differential case is a shim, adding an additional shim will cause the spider gears to bind, effectivly creating a "locker". ANOTHER RESPONSE: ... The extra shim was another trick we used to lock up the rear in the street stocks. The idea was if the tech guy jacked up the car after the rearend cooled down it would act like a 1 legger(a pretty tight one at that ) as the rear got hot it would tighten up and act like a locked rear which is great .
I tried that when I first got my 70 mustang in 94, it worked for a while. Then it wore out taking the bearings with it from the metal particals from the shim breaking up. I think it also jacked the gears but, I can't remember for sure on that. I changed to a alburn pro and 3.55 gears, the alburn is toast now. It works turning right and some times going straight. This is an 8" rear end too with ARP cap stud kit.
I ran one in my 67 mustang with a 460. It worked great for the 3 years I had the car. Never a problem and it always locked both tires on launch. I had a very knowledgeable ford guy (best in the business!! imho). If I remember right, he was very particular about what size of shim to use. It was a 9 inch, 3.50:1. I dont recommend this for everyone, but it worked for me. The car was a daily driver during college and saw a lot of miles but I can see where this could cause problems...
I got the shim from a rear end shop cost me $4.00, it was the same as the one in the rear so I stacked them. I did it myself and that's probly why it didn't last, I think it work for about a year or two.
Never heard about the shims. Is it supposed to work like a locker only locking up when you need it or is it like a spool? I had a buddy that welded the spider gears but that was essentialy a spool rear. That worked for him for a while never heard him have any problems. I just did it the right way put 3.80's in with a spool and i love it! 74Maverick, Thom
its the same thing as welding the spider gears together...dont waste your time doin something like this, it is a waste of money and will damage your rearend. will set you back more money than its worth...and will always have locked axles (your tires will squall around corners) same as having a spool.. if its for the street dont even think about doin this. i feel bad for the people that have tried it
Spool Yep, Know all about the squalling and screaching. I dropped my tire size from 275 to 245 and it stopped. I also take it a little easy around turns. I only put about 1000 miles on my Maverick a year which probably plays a major role in me not getting frustrated. For everyday driver the spool would be no good, but for me it rocks:bananaman . 74Maverick, Thom
It is not the same as welded spiders, adding the extra shim is preloading the spider gears thus making it harder for them to move. They do still move unlike welded spider gears. I personally would not do it again but, it does work. I would go for a lock-right type posi, which uses the same principle as the extra shim. They just use springs and replace the spiders with a machined block.
Yep, I've done it too. I just used 2 extra shims, one on each side gear, then bolted the ring gear onto the "spool". This effectively causes extra bind between the side and spider gears and it's MUCH harder for them to turn. In fact, mine was so hard to turn, it would chirp around some tight corners, just like a full or mini spool. It did work at the drags though....that was when I had the turbo 302 in it. Too bad it fried some spark plugs, it really would have burned up some pavement.
Like I said, I never had any problems with mine. They didnt squall around corners. You didnt even know they were there till you launched and both tires would spin all the way. Still, I dont recommend this, it can (and probably will) cause problems. I knew the risks and I think it was worth it...won many races with the help of them. People also seem to swear by mini-spools. I have heard many horror stories about them also. Just depends on what you want from your car and how much you are willing to pay.
I guess for a daily driver this would be a bad idea ... But on the other hand if you had one that you just ran at the track one the weekend this might not be a bad idea providing it was done right ...
