Call Jesse at High Angle Drive line and get an expert opinion.
Pass drop T Case for 1987 4runner (1 Viewer)
- Thread starter Heavylead
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You won't have any issues with the rear 80 series diff. I know a few guys who run them with a centered rear t-case. No Problems. You will have problems with those shafts though. They suck, so does the company who makes them. Stock shafts are waaaaay stronger than nitros. Happy to elaborate on my experiences with that company.
40" shaft with 12" drop, difference between centered and 4.5" offset is about 1/10° 1.23°
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- Thread starter
- #44
Good to know someone else has done this kind of swap before I could really find any write ups of running a center T case and the rear 80 series axle. That sucks about the nitro axles a couple people have said that now. Well I have them so gess Ill run them until they break. I tried high angle drive line no answer ill try them again soon. Just to see their opinion. Definitely feeling better about running it though.
I'd run the stock shafts as somebody else mentioned above. When one of my nitro shafts broke it took out my arb and a 4.88 gear set. I should have learned but I installed another 4.88 and a Detroit full carrier locker and the other shaft did the same thing. I sent both shafts back to them, got a confirmation and that was it. No replacements no other responses since. Horrible product , worse customer service.
I've been running a welded rear and stock shafts since - no problems.
- Thread starter
- #46
Man what a horror story. So I just talked to high angle drive line, Jesse said he wouldnt run the truck with a factory 80 series axle on the street. The vibration will be too much. That was his opinion on it.
37's 5.29's and 60mph is right around 2900 shaft RPM.
40" length with 12" drop is a 16.7° angle. Assume a proper perfect equal and opposite Trans and diff at 3° and you get 13.7° operating in the vertical. 5.7 horiztonal. Which makes a 14.8° U joint operating angle at the T case and at the diff.
ROUGHLY speaking with a CV shaft and the diff pointed proper, your actual shaft angle would decrease to about 8.5°, the CV head would then run at 5.5°, the vertical at the diff would run at 0°, and the horizontal at the diff would be 5.7°.
I'd run a CV. 5.7° wont rattle your fillings out at 60mph and probably last as long or longer than a joint running at 14.8°. A single joint at 6 degress is going to be smoother than a "cancelled" 15 degree joint at 3k rpm.
Is it perfect? No. Will it run satisfactorily at 60mph? Yes.
If you want it perfect smooth as glass upto 90mph, then you run a closer to center diff and still a CV.
40" length with 12" drop is a 16.7° angle. Assume a proper perfect equal and opposite Trans and diff at 3° and you get 13.7° operating in the vertical. 5.7 horiztonal. Which makes a 14.8° U joint operating angle at the T case and at the diff.
ROUGHLY speaking with a CV shaft and the diff pointed proper, your actual shaft angle would decrease to about 8.5°, the CV head would then run at 5.5°, the vertical at the diff would run at 0°, and the horizontal at the diff would be 5.7°.
I'd run a CV. 5.7° wont rattle your fillings out at 60mph and probably last as long or longer than a joint running at 14.8°. A single joint at 6 degress is going to be smoother than a "cancelled" 15 degree joint at 3k rpm.
Is it perfect? No. Will it run satisfactorily at 60mph? Yes.
If you want it perfect smooth as glass upto 90mph, then you run a closer to center diff and still a CV.
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I concur with the CV shaft. Any idea on the correct drop? I just pulled 12" out of the air.
Am curious how you got your numbers?
I mathed them out and also doodled them in Solidworks, got different ones. Looks like you did 40" horizontal, not down the shaft? Just trying to understand why my numbers don't match
- Thread starter
- #49
Alright guys I really appreciate all the discussion and ideas everyone has shared with me. I am going to go with the centered diff just because I dont want to get the 80 axle under there and not like the vibration it gives off. So I have some parts I am going to post if anyone is interested. Thanks again.
Good catch. I did use 40" improperly. Guess thats what happens when I just rattle numbers off into the calculator. Paper would help. The numbers would change slightly then doing it the right way.
I went through hours of reading on this subject because I'm building a 4runner on an 80 chassis. I settled on using a 98+ Isuzu Rodeo Dana 44. They're not a regular 44 and actually use a Dana 60 size pinion with a thick cut gear set. I'd argue it will be at least as strong as a stock 80 rear albeit without a full float design. They are 63" WMS, have 4.10 gearing, disc brakes, 6 lug and can be found really cheap in a pull-a-part junkyard. I picked mine up at the local place for $130. Installing gears/lockers in it is going to be a little unconventional, but I think it's going to work. I'm following this guy's method:
Will it work? Who knows, but it seems like it's going to be a really good option for the price. If it does work, I'll post up a build once I'm all done.
Will it work? Who knows, but it seems like it's going to be a really good option for the price. If it does work, I'll post up a build once I'm all done.
- Thread starter
- #52
So what did you find that made you not want to run the 80 series rear axle?
Basically the inconsistency around whether it would cause vibration issues. I didn’t find anything definitive though. Also, if I find an 80 rear axle, I may still go that way but only if I find one in a junkyard between now and then.
Also, I like the availability difference. If you look up your local junkyard, I’d bet there is a 98+ Isuzu Rodeo or Honda Passport sitting there. If I break an axle, there are plenty of spares available. It’s a little harder to find junkyard 80’s.
