TH 400 Problem Very hard to go

[njdevi11]

I'm just throwing this out there but i'm not too worried about it since I'm swapping to a manual soon.

I Started up my CJ today, drove down the block and back to load it and get the temps up. I took it back to my driveway let it idle for a little while and checked the turbo pressure, EGT's and the Temp. I let it cool down I hooked up my oil cooler lines and then went for another test drive. I got about 3 blocks and i went to make a k-turn and i shifted into reverse and all of a sudden it was like i had a trailer on, Letting off of the break the jeep didnt move. I thought the breaks locked up. I Gave it some gas and got the jeep pointed in the right direction. Shifted into neutral and it rolled fine when i pushed it. She brakes were not locked. I put it into drive and I could barely get it moving to limp back to the garage, the engine strained really hard. By the time i got back my EGT's went from 200* to 800* and the temp was up to 220*

With the t-case shifted into neutral the engine revved fine, with the transmission in neutral it revved fine as well. I don't know if its the trans or the t-case but something was hard to move. The t-case is a NP203. I'm swapping the th400 and the np203 for an sm465 and np205. I hope its just the POS np203 thats the problem. The trans pan felt warm but wasn't too hot. The trans fluid on the stick was a healthy red color.

I'm letting it sit over night to cool down tomorrow im going to work the shifters back and forth a few times then give it a try.

[grancito]

when you reved the engine with the transfer in neutral, was the TH400 in gear?
If so, then the transmission is not jambing.

[njdevi11]

The trans was in gear when I was reving with the t-case in neutral. I don't suspect the trans is that likely to go because I am sure there is fresh fluid and filter in it. Also, a th400 is hard to break. Also since the problem in foward and reverse it leads me to believe its the crappy NP203 that had a bearing fail or something like that.


Yesterday I jacked the back wheels off the ground and put everything into gear, things seemed to work ok, the wheels took off when i put it in gear. As soon as i put the wheels back down it happened again. My rear brakes are not much to speak of so that didn't help much in terms of stressing the drive train.

My only other possible thought is that now my engine is not putting out much power but thats a long shot, i don't have any smoke coming out of the exhaust.

I'm pulling out the th400 and np203 either this weekend or next... well see what happens when i put the 4 speed in. Ill take the 203 apart and inspect it, ill probably find what im looking for.

[grancito]

The last time I launched my boat on the sand with the 82 chev, it was like yours, felt like the brakes on. Then back at home backing through soft sand to park the boat, one locking hub failed, and so after much back and forth, spinning the back wheels and hearing horrible sounds from the back end, I pulled the back plate off the diff and found the carrier housing split in two. Turns ok with no great force against the crown wheel from the pinion driving it. Worth checking. The diff ratio is a wierd one and everthing inside is destroyed so it is still on blocks.

[njdevi11]

The diff back there is an AMC 20, Pretty much the only weak points on it are the small drum brakes and the relatively thin walled axle tubes. I'm not sure of the exact size but the ring gear is some where around 8.25". Its somewhere between a dana 44 and dana 60 in terms of shaft and gear strength. Then again I wouldn't be surprised if thats what happened. It sounds very likely, The jeep is over 25 years old ('81) and if that wasn't enough, when I went to get new calipers for the front I found out that the front axle was from a '78 or earlier.

Of course ill never know until I open it up, But I've got a dana 60 full floater sitting in my back yard right now waiting to go in, My new spring plates and U-bolts I ordered are scheduled to be here today, so hopefully this weekend ill install it.

Oh yeah, I've also got an extra amc20 w/ one piece axles lying around I could swap the parts from that if i wanted to.

I also just remembered a few weeks ago it snowed and iced up real bad, The drive way is real steep and I hit ice on the way up and ended up spinning the wheels for around a minute or two until I got a good foot hold, Wouldn't be surprised if that gernaded the diff. Then stopping and throwing it into reverse finished the job.

[grancito]

mine is the 9 inch heavy duty option, but the crown wheel carrier has a weak point where the limited slip clutches fit. You are lucky having backup parts, tomorrow I´ll look at a 4.56 ratio, which will be near enough if I put 2 inch larger diameter tires on the back.

[njdevi11]

Unless your ring and pinion are damaged you can reuse them on a new carrier. Keep in mind, Unless you have an all wheel drive t-case your front wheels are not engaged all the time and the ratio's are not going to matter if they don't match. If you have a part time transfer case, Put what ever you want in the rear and don't put it in 4wd unless you have a low traction situation (pretty much anything off pavement).

If your ratio is that weird, you might as well just find a standard ratio pair for probably close to $150-$200 and use that, it will probably be cheaper then buying a brand new weird ring and pinion.

SPRING PLATES AND U-BOLTS CAME TONIGHT! IT'S AXLE SWAP TIME THIS WEEKEND!

[grancito]

A spidder washer went through the spider gears and removed teeth then through between the pinion and crown wheel and took teeth off there, so it´s history. I can get a whole diff-axel assembly for $130 and two used 33 inch tires for $30 each so have it going for $190 and only 0.3% difference in road contact speed between the front and back tires. It´s part time 4wd so is used only in soft sand, lots of that here. Can get the front diff from the same truck (don´t have a price) but that is a lot of extra work. Good luck with the axel swap, no frozen bolts like my truck with 13 years at the beach.

[njdevi11]

I opened up my rear diff and to my disappointment it wasn't shattered into 1,000,000 pieces that ran out of the case with the gear oil. Instead I found this.

It looks like its the culprit, i jacked up one wheel and it was significantly harder to turn in one direction then the other. It definitely did not spin freely in either direction.

I think im just going to slap the dif cover back on this weekend and flat tow it the 3 miles back to my house (Thats where the good electric and the welder are) so I can swap in the dana 60. I hope the yokes are both 1310's and the difference in drive shaft length is negligible with my adjustable spring perches and plates.

[grancito]

The symptom of more drag turning one direction than the other is normal for turning the transmission from the drive shaft end, that´s what you did by lifting one wheel off the ground and turning it. So it sounds like a collapsed bearing somewhere that binds up under load. Drop the drive shaft and drive it in front wheel drive to see what happens. I have some transmission jamb histories if you think it could be there, and a stripped trans box drive in high that worked in low saga also.

[njdevi11]

Drop the drive shaft and drive it in front wheel drive to see what happens.

I would except I don't have a front drive shaft as of right now. :confused:

The carrier is cracked, that is what that picture was of, It wasn't cracked all the way through but it would make sense that its deforming enough under load to bind. That's what I was trying to get at in my last post. Also the collapsed bearing sounds like its possible, I'm going to swap the rear diff this weekend and see if that solves it. If not, ill start working my way down the drivetrain.

[grancito]

I seem to have lost a day, 2 days rebuilding the broken diff, and now have the chev out of my work area, the diff screams on the road but is good enough to take the boat to the beach. Also repaired the front locking hubs for the 100 th time and removed the unlocking springs, worst things GM ever made. the crack in your carrier should not cause enough distortion, I found when welding mine that they are a type of cast iron and had to use a stainless steel type rod for disimillar metals. Keep searchng.

[njdevi11]

I swapped out the AMC 20 for a Dana 60 and the CJ drives like normal now.

Looks like the trans and the t-case are just fine. Oh well, I'm still swapping them for a manual.

[grancito]

Hey that´s great that you have it fixed, I looked at a diff a few days ago but mine is a heavy duty option and the pinion is longer than normal and the drive shaft won´t reach the replacement. Think I´ll swap the front diff parts to the back.