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Kzj/lj70 gearbox rebuild

Bazxhi

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Sep 22, 2021
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Evening all , Iv currently got a kzj70 with a tired trans , I sent it off to a specialist and long story short they say they can’t source the parts , understandable , but I have a donor box of an lj70 , by the looks of it there near on identical, bar the bell housing and the sensor on the gearbox . So I’m going to put the kjz bell housing on the lj box and put it back in , the one thing that I’m struggling to get my head round is the sensor on the kzj box that’s not on the Lj box .
I presume it’s reverse light ?
can any one enlighten me on what it is , and off so what I do with lack of said sensor on the lj box
Any chance would be much appreciated
Cheers
 
What is the gearbox code?

In the H41/H42/H50/H55F manual the only sensor attached to the gearbox is "Back up light and shift point sensor"

Does the KZJ have a light on the dash that tells you when to change gear and or any kind of light related to gearbox?

My guess is this sensor is not in any way critical to the operation of the gearbox.

Check also whether the input shafts on the two boxes are the same. Length/number of splines.
 
Cheers for reply ! I’m not 100% sure what the gearbox code is , do you know where il find this ? No there’s no light on dash that has anything to do with the gearbox , I’m thinking it probably won’t matter either was but I’m just none the wiser to what it may be , maybe oil level ?
 
For your truck it will be on the vin plate riveted to the top of the bulkhead at the back of the engine bay. It's probably an H55F. On the LJ box im not sure. I've got one on the bench here. There are paper stickers on top of the transfer box but mine have worn off. There are also codes stamped on the front (4 speed) ... part of the box, and rear (5th) section.
 
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Hi Bazxhi,

I think you are right, the switch on the KZJ gearbox is for the reversing light. That car doesn't have any other gearbox gizmos. Looks like if you want to keep that feature you will just have to put in a manual dash switch for it instead. Like outdoordan said, measure the shaft length and count the splines. The gearbox may well fit OK, but the ratios are not all the same.

Assuming your gearboxes are standard UK spec, LJs have R151F gearboxes and KZJs have R150F boxes. Third to fifth ratios and reverse are the same in both, but LJs have lower ratios in first and second. The drop in revs when you go from second to third in the LJ is almost 50% greater than in the KZJ. You will really notice the difference.
 
Thanks mate appreciate that ! Il have to wire a switch up then , as I can’t source the parts I need for the kzj box . Going to try get the lj box in this weekend , il check shafts and make sure there the same , touch wood they are !
 
Or I could source a r151f box from a later Colorado and use that as a donor
 
Since you already have a donor box from an LJ, I wouldn't bother. So long as it fits it will work just fine. It's a good strong gearbox and hard core off-roaders prefer these boxes because of their lower first gear. Personally, I don't consider they are well suited to the characteristics of the puny standard 2L-T engines we got in the LJs here in the UK. That big jump from 2nd to 3rd is a bastard when you are towing uphill with an asthmatic 2.4, but the 1KZ engine is a completely different beast and probably won't have difficulty with it at all. You will notice the difference, though.
 
Got the lj box in , it does have a reverse light sensor too , just in a different place to the kzj .
ratio isn’t an issue at all , I can’t really see a lot of difference myself , cheers for the advice chaps
 
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