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over the last few weeks I have been working on a old set of 4.89s. they will replace the new 4.89s I have in the 52. once the old set is "set up" and in the 52. the new set of gears will get ARB's and installed into the 265 truck to replace the stock 5.83s.

we started by cleaning everything and dressing up the water damaged gears. after many hours with a razor blade the gears looked passable. I was all ready to swap around the diffs when a bit of end float was noticed on the pinion of the best gear that was going in the back. ... no problem I thought

after tearing apart 5 loose 5.83 diffs looking for a thinner hardened spacer (to make up the difference and get some preload on the pinion) I was subjected to days of sanding to remove .030 from the hardened washer.

with the pinion pre load set it was on to the laborious task of setting the back lash. torque the caps loosen the caps........ after a couple hours we were patting each other on the back

then we noticed this :

out comes the carrier, off with the gear, new carrier with good side gears and back to setting the back lash.

Wish the pics were bigger, I can't see what it is that you saw that made you take it all apart again. I use Postimage and use the link "hotlink for forums". It give a nice BIG picture with full detail.

It takes a minute when inspecting parts to "Gain An Eye" for all the wear and failure modes a part can have. Now however, you can turn a "Splined Eye" to the side gears!

Those splines don't look stock.

Bert

she was stock at one time, now only half of each tooth remains. 4.89 chunk pulled from a 53 b3 retired fire truck. I have never seen side gears worn so bad. could it have been from the water sloshing in the tank ?

I have seen that, On our old Dodge brush truck as a matter of fact. The taught procedure, at least before I took over as engineer, was to engage four wheel drive BEFORE leaving the pavement. That meant a sharp turn on pavement with four or five guys and a pump and 2,000 lbs of water. Something has to slip when in four wheel drive and it was usually an axle breaking. They kept a stock of spare axles. I said this is crazy, how hard is it to pull off the road and THEN put it in four wheel drive? Never broke another axle. But I replaced a couple center sections due to the extreme weight and stress of turning and the strain it put on the side gears. I have also seen that in high powered trucks with Detroit lockers where a majority of the power is pushing on one side a lot of the time.

I was reading about 4.89s, is that a must have swap if you plan to travel on the road between areas a lot? I see there is basically only one place to get the gears, I am getting ready to do some work and I was thinking about it. Any advice is appreciated.

you may remember a dyno post with the stock 230 pulling 53 horses. if you find your truck under powered now it will only get worse.

4.89s are going into a m37 powered by a 265ci ind with twin 32/36 weber carbs, to hopefully make up the difference.