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231HD Tech

R

RalphXJ

NAXJA Forum User
Location
Columbiana, OH
Ok long story short, installing my SYE I relized that I had a few issues with some stuff. Freindof mine had a spare case that he gave me to use for parts its a 231HD out of an 88 Dodge Dakota. Everything looks exactly the same except a few things. I want to make sure I get all the HD parts I can, and also make sure everything works together.

The HD case has a synchro gear(gold in pictures below) Is this something I should use in mine, or doens't this help anything? Also i'm not sure if this has the wider chain or not, have to wait till tomorow when I pull mine apart and compare! Is there anything else I should look for in the HD case? The main part i needed was the shift fork, with is steel in the HD case, and Aluminum in mine(mine was badly worn). It only has 3 planitary gears, so that stinks, but oh well. So I guess the big question is do I need the synchro gear, and what exactly does it do?

part1.jpg


part2.jpg


part3.jpg


part4.jpg
 
Not sure why they removed the synchro's but all older 231 cases out of YJ's and XJ's I've seen have had synchro's in them. Somewhere in the mid 90's they stopped using them. It is not specific to the "HD" case.

Here's a shot of some TJ 231 gears and some YJ gears with the synchro.
http://community.webshots.com/photo/67867092/67867502idolwF

Also, all older standard 231 jeep cases I've seen have used steel shift forks while the newer ones use aluminum....nothing to do with a case being "HD" or not.

Here's a shot of an older YJ shift fork and a TJ shift fork.
http://community.webshots.com/photo/67867092/67867499LoOMsL


The standard NP231 case has a 1" wide chain. If the one from your donor case is 1.25" or 1.5" wide it is larger than the standard jeep 231 chain.
 
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My 92 doesn't have the synchro's, but my tcase was replaced by a dealer 3 years ago(before i knew anything about jeeps) so i dont know if the case I have is really from a 92 or not, but anyway I dont have them in mine currectly.

Should I use them? What do they do?

I'll be installing the new parts tonight after work, so i will check if the chain is wider, I didn't seem to be any diffrent, but then again I probably wouldn't even notice 1/4 unless I had them both together to compare!
 
The stuff in your picture from the TJ is what he stuff from my XJ looks like. The stuff from th YJ is what the new stuff from the Dodge case looks like.

What does the synchro do? Should I use in my case or not? Is there a benifit to using it?
 
I'm guessing they changed the shift fork to save weight.

The synchro's were probably found to add little value to they removed them simplifying the t-case and eliminating a potential failure point

I've ran t-cases that came with and without synchro's and didn't notice any difference.
 
Well I need to run the new fork since my old one is very badly worn(which is the main reason i got the new case)

and I guess I wont bother with the synchro, doesn't seem to be very important unless I'm missing something?

Thanks.
 
don't those cases (the hd's) come sye'd what is different about them that would make you not just swap in the hd case?:dunno:
 
The case I got did not have an SYE, it had a tail cone about 2in longer then the one that came on my XJ.

I really only needed the Shiftfork but he gave me the whole case. It had been sitting at his shop for like 5 years and he didn't know if it was even good(truck was not running when he got it to part out) so I didn't want to mess with putting the complete case in mine when I only need one part.

I just want get all the HD parts out of it I can while I have mine apart(its still in the Jeep though).
 
To answer the question about syncros. They help you get it in gear without grinding the gears.
 
To answer a couple of HD questions, the chain and all gear parts related to it won't work in a non HD case, it won't fit. Notice the case is thicker where the chain rides? Also, you can get a good idea if the case is good by just plain and simply turning it by hand and feel for to much slop or crunchy feeling, or noise. If it has none of the above, put an SYE in it and run that one. IMOP.
 
In case you look for another in the future-I think the one you want to look for in a Dodge is the NP241DHD. This is the one w/ the wider chain and sye already in it. I am not sure about what years it came in.
 
I'm not sure the case you are trying to get parts out of is actually the HD one. The chain will be wider as well as the front output gear that the chain rides on and the piece on the main shaft that the chain rides on. However, it is my understanding that the truly HD cases use a larger diameter shift collar and the matching piece that the shift collar shifts onto. I can't remember the exact names of these pieces. Anyway, check out my article in the tech section of www.madxj.com for some pictures of different components. Do a google search too as there is a bunch of inf. on this on the web. Jeff
 
Thanks for all the help, I got it all working again!!

I only needed a new shift fork, I got the complete case from a freind who didn't need it anymore! It was fine when he removed it, and I could tell just by turning the output yokes that the case was in good working order!

It was a 231HD, the tag said so. I was just hoping it would have a wider chain, or other beefy parts, it didn't matter that it didn't!

T-Case is finaly all together, and the new Tom Woods DS's are installed!!
 
RalphXJ said:
Thanks for all the help, I got it all working again!!

I only needed a new shift fork, I got the complete case from a freind who didn't need it anymore! It was fine when he removed it, and I could tell just by turning the output yokes that the case was in good working order!

It was a 231HD, the tag said so. I was just hoping it would have a wider chain, or other beefy parts, it didn't matter that it didn't!

T-Case is finaly all together, and the new Tom Woods DS's are installed!!
Click to expand...
Well, if it was an HD something must have been beefed up. So tell us ... did you put the "new" fork in your old t-case, or did you put the entire 231HD t-case into your Jeep? You didn't really explain what you did, all you said is that it's running again.
 
All I used was the shift fork in my Jeep t-case. I didn't see anything else any diffrent other then the shift fork was steel and much stronger then the aluminum one in mine!
 
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