Just wondering since a powertrax lockright #1810 fits both the 8" and 9" rears, and both 28 and 31 splined axles, does a 9" 31 spline side spider gear fit in an 8" case? I have heard the 28 spline axles are the same in same width 8" and 9"ers. Sooo, why cant a 31 spline fit in the 8"? Thanks.
I think the problem you would run into is that a 31-spline axle will probably be too big in diameter to go into an 8" differential case.
For example: The parts inside an 8" TractionLok and a 9" TractionLok are the same, so you could put 31-spline axle side gears in an 8" TractionLok. So I suppose you could also change the side gears in other 8" lockers from 28-spline to 31-spline.
However, I have seen several 9" 28-spline TractionLoks that had a small enough hole on the end that a 31-spline axle would not pass through. Apparently, many original-equipment differential housings had different axle openings depending on the axle size used. There is a good chance that many 8" differential cases are not made for the diameter of a 31-spline axle since that was never a factory option on the 8".
If you are going to install a locker unit that fits inside the factory differential case, you should measure the axle opening of that case first and see if it is large enough for a 31-spline axle to pass into.
Just buy the locker unit for a 8" and get 31 slpine axles for a 8".I should've gotten 31's for mine but i did the center section before i did the axles,so i was stuck with 28's.
I might be off with this, but I kinda got this idea from when I was doing research on upbuilding my 9inch open rear to a traction loc with new axles. Someone correct me if I am wrong here, but orginally they were doing those big 31 spline axles because the smaller 28 spline axles were weaker (weak is a relative term here). But, todays manufaturing allowes for a really strong axle to be made without having to go big. In most cases its hard to stick a street car to the ground hard enough to twist a currie or moser aftermarket axle. If you are building a strip car the 8 will be weak in other areas that will need addressing.
Seems like many people go after the 31 spline like turning up to 11 (spinal tap), just because its more than 28.
Someone chime in...I have never voiced this idea before, but have had it in the back of my mind.
I have 31 spline axles that will fit an 8" I picked up by accident. Well, they are for a factory 9" that has small bearing size. I wondered if they would work in an 8. I didn't know if the side gears would swap. But I've never heard of putting 31 spliners in an 8 anyway, I just thought it woud reduce unsprung weight using an 8.
Mostly because I dont have a housing, nor do I feel like putting a grand in right now. I figure the only sunk cost here is the gear set and set up kit. If I ever switch to a 9", I already have the axles and locker unit, which seems pretty durable. I have one in my Dana 70 rear and works great. Also, I am nervous about having to shorten the driveshaft, since it was a $400 aluminum piece this summer with my t5 swap. And lastly, I feel my t5z will break before parts other than axles will in my setup. I dont have alot of torque, but pull strong until 6500.
Yeah, kinda like putting a billet crank in a stock block. My axles were doing just fine. But I finally decided on a 9 when I thought about bracing my 8in. Everytime I took it to the track it would leak after the first launch.