I have a (I believe) 69 casting 3 series 12 bolt carrier that I'm putting up for sale. What gear ratio's will be able to go on this carrier(for advertising purposes) 3.08-3.90? Completely rebuilt with brand new parts, HD springs and clutches, new bearings and races, never used. Was going to list it for $300. Going to throw in a brand new Spicer HD TH400 trans yolk and a Mark Williams Billet steel 12 bolt bearing retainer cap. Thanks ahead of time, Tom Oh and yes, It DOES have 33 spline aftermarket side gears, so anyone building a 12 bolt should upgrade to new axles, and order them 33 spline instead of the stock 30 spline.
Tom. That is correct. OEM 3-series 12 bolt diffs were for 3.08:1 to 3.90:1 ratios. I may be interested in this BTW.
I have some pics Like I mentioned, this is all new parts other than the housing itself. The guy I got it from said the posi unit came from a very low mileage wrecked Chevelle. Gears,springs,spring plates,clutches,bearings/races,crosspin,crosspin bolt is new.
When you converted it to 33-spline,did you hone the insides of the bearing hubs,for the larger axle to pass through?
Looks to be aftermarket like a Moroso unit- Look for a stamping in the case .... usually on the balancing bump above the larger open spider gear cavity window. That unit has 800 # preload springs. Really not a street unit... You will wear out the clutches pretty quick with that much preload on the street. Moroso sells them for 940.00 now. THIS IS a ridiculous price as they can be made for MUCH less. Rip off in my opinion... They only come in 4 series... So if this is a 3 series then it was definetely made by someone else... As Brian stated you have to have the bearing hub inner diameter honed out to fit 33 spline axles as stock size casting was for 30 spline axles only. Jim
I was building a Gasser a couple years ago that had a 12 bolt in it when I bought it off the old guy who had the rear narrowed by either moser or mark Williams. I would think it was done by Williams, since it had (MW) on the ends of the 33 spline axles that were in it. When I sold the car, I kept the posi unit thinking I was going to put it in a 69 Impala I owned. Didn't realize until after I sold the car, and sold this unit to a friend that it was 33 spline. His car has stock 30 spline axles, and he didn't want to mess around replacing axles, so I gave him his money back. But to answer above questions, yes 33 spline axles fit through the case.
What u-joints is that yoke made for? I may have a use for all of that. I would take the springs out altogether. With a properly tuned unit,you don't have to rely on those springs to put load on the clutches.You can have a nice tight unit that last a long time. There was an article written about this in the early 80's,that was very informative.
I would keep springs (JUST NOT the 800# go with the 200, 300, 400 depending on your needs) unless you are familiar with what that entails as conducive to instant grip as a preload spring provide and springs will also keep the clutches snugged up when the clutches wear down the road to keep it consistent. BUT AGAIN- it is your posi so you can do what you feel you can handle. I know I have a difficult time selling that to the customer. THEY want to see springs. lol. Brian - I have a strange 1350 400th short yoke also if you need one. U1664 part number Chrome Moly TH400, 2nd design Super T-10, 4L80E 32-Spline Fits 1350 Series 5 1/2 Overall Length
I know,it's hard to sell it without the preload springs.They see them missing and they panic.I don't have them in any of my personal stuff. Also,with the Eaton units,I do not suggest the 22 disc kits.The clutches are thinner,and I have seen them break in the more serious applications.Dont use the flower petal shaped ones either. Use the original 18-pack of knurled steel.
If I don't sell this outright, I would mention that I'm looking for 64-67 BOP 3.55 gears. My car has a 2.93 posi,and I would like to give it a more fun gear for seat of the pants driving.
