BlazeN8

I've got progress on my center mount diff build. The driveshaft from a 1986 4 Runner doesn't have the ability to extend over and down for this geometry. The good news is I have a driveshaft from a T-100 SAS sitting around that does. It has a much higher angle as you can see in the photo. But nothing is that easy..... turns out the 4 banger transfer case output flange has a different bolt pattern than the T-100 V6. So I had to machine in the correct bolt pattern. FYI- Marlin Crawler has a replacement one with multiple patterns for those of you without access to a mill. That said the T-100 driveshaft works great.

The next order of business is to mock up a longer CV. I placed a few CVs side by side. Stock, T-100, and the Center Mount. The mock up C.M. CV is just a PVC pipe, some couplers, and hose clamps. I cycled the suspension and found the proper length. The angle of the CV is much reduced as is the plunge in the inner tripod barrel. Lastly I sleeved a set of CVs with steel tube welded in place. Today I will be doing a road test. I'll post the results in a bit.

motorhead

Something like this might work well on a 5m/7m swap with a cressida pan without a bracket lift, as the pan sits in front of the ifs diff ...if one were to use the mkIII diff from a supra, supra axles (or at least the inner joint and shaft) might be an ingredient in getting the right length in that they are made for a centered diff...

dark_fairytales

that is a good idea. I might have to look up the length of the MK3 supra axles.

BlazeN8

Well I drove around most of the day on the new setup. I had the hubs locked in and the transfer case in 2wd most of the time so the front drivetrain was spinning. I did about 10 miles on the freeway at 70 mph and couldn't feel or hear anything unusual. I also unlocked the hubs and put the transfer case in 4wd with similar results. I don't trust my sleeved axles to drive around on the freeway in 4wd with hubs locked. Next week I will hit the dirt and see how the sleeved axles hold up. Maybe I'll try and climb a dune or something.

I was at my buddies shop this afternoon and he is in process of building a centermount diff using the Supra 8" diff. The bolt circle for the CV flange is the same as the 4x4 CV only the studs are a size smaller. It could be drilled out for a larger stud or some cone washers or something. Also the mounting surface width is slightly wider for the 8". The width is 9-3/8 for the 7.5 and 10-1/4 for the Supra 8.

FYI-Sway-A-Way can make custom CVs axle shafts for the Toyota 4x4 at what ever length you specify.

RBX

Nice info, especially if you can fine a supra 8" with LSD.

motorhead

For those with access to a machine shop or friends with Strange Axles, one could take a bent rear axle housing, narrow it as much as possible, and then figure out how to hold up the snout of the carrier with some sort of yoke that surrounds it. It is normally carried by the leaf perches, so maybe mounts could go on the axle tube stubs. The outer flange that would normally carrry the drum and wheel could be modified to attach a cv flange to...car guys have been narrowing housing for decades, and an electric elocker front would be really cool.

I must show that I have been thinking about this since I saw Brian894x4's page on gear tech years ago that showed the supra diff...I actually had a 4.30 lsd in my parts car, but really needed to make space, have no welder, and am having enough trouble finishing off my 7m swap and patching the holes in the body to get a few more years out of it that I just got rid of it.

BlazeN8

Yeah I really like the Supra 8" diff and know there are probably a few of other options that could be created! But, I think the 7.5 diff concept is the most economical route in my situation. I allready have 3 spares sitting around rusting away. I see them i the salvage yards all the time; heck they just discard them for scrap! I could fairly easily reproduce what I built. When I built my setup I took notes and measurments. I could draw it in cad and have stuff laser cut. I allready built a couple of fixtures for welding the brackets together! There are a few items one would have to obtain from the salvage yard. And it wouldn't take much make your own sleeved axles. Heck I can order a 22' stick of tube with the proper O.D. / I.D. and cut it to the proper lengths. I don't know how durrable the sleeved axles will be, but if you break one it will be super easy to and cheep to sleeve another one from a salvage yard. I would estimate cost would be $200 for the brackets $20 for each axle sleeve tube. The stub shaft, and 2nd driver side diff hanger $40. Machining the diff housing was $80. The total is now $340. Finding the right drivshaft might be a problem? Then you need to get the correct output flange with the appropriate bolt pattern. I would estimate this setup would allow 13-14" of travel with 4wd. My Blazeland LT kit maxes out at around 12". The Rancho Gen II kit I built may be able to cycle 13-14" but someone else getting an old rancho kit is not a realistic option since it was discontinued in the mid 1990s. And you really need a 4" drop bracket kit for oil pan clearance. I suppose this really only makes sense as a one-off experemental project. Anyway I will keep playing with it and see what developes! Cassidy what is your latest on your build?

dark_fairytales

I have been thinking of doing this for a few years now. blaze you mention that you need a 4"
drop bracket lift for this to work. another option is a three in drive train lift, which is the path im taking.

Tofer

subscribed.

BlazeN8

I located a couple of options to build the new axle shafts. As I mentioned Sway-A-Way will do it, I got the price qoute.... about $700. I found another guy who is building the axles for TC for their T-100 LT. Using the Blazeland Long Arms and the Center Mount Diff requires an even longer axle. I will be meeting him next week with the mock up sleeved axles to get the designed squared away. His estimate over the phone...$300-$500 for the pair.

dark_fairytales

good info. blaze, thanks for doing the ground work.

BlazeN8

Well I ran into a discouraging find. The centermount diff will only cycle about 13" of travel, anymore and the CV will bind. The good news is its another inch of travel over the stock differential location. I was hoping for more because my Rancho UCAs w/ Blazeland UCA Extension Brackets will attain close to 14" of travel w/out 4WD. (please note this setup is for mock up purposes only, the Rancho UCAs are too weak to handle the added leverage of extension brackets)

RBX

Very cool, keep up the progress.

dark_fairytales

to bad it is only one more inch. I'm guessing the outer cv is the one that binds. In any case an inch is an inch.

BlazeN8

Its actually the inner axle contacting the inside of the barrel at the tripod joint. The plunge is fine but the angle is the problem. The axle makes contact at 22-23 degrees. I have heard of people modifiyng the barrel with either machining or grinding for a greater angle. I may look into it?

ccraviotto

with the center mount the plunge is reduced.i run my axles about 3/8 inch shorter then the math figures.Why? The further the axle is engaged in the barrel the sooner it will bind.

dark_fairytales

well a set of 930 cv's would solve that. better yet some a Cornay cv joint.

joediesel

Awesome effort wish i had thought of putting the cross members over the diff!! I have just done a supra rear into my 93 with Porsche 934 CVs and 300m axles.The supra rear unit accepts UZJ100 land cruiser solid collars/ install kits and Air lockers which is what I have. Totally indestructible.

motorhead

Pics of that install? I assume you had shafts made for the axles...

dark_fairytales

I would like to see some pics of that set up too. I'm interested to see how you have the CV's setup. I'm also not familiar with the term you used " solid collars", curious to find out what that is.