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Junkyard Gears?

CanMan said:
Setting up used gears can be a PITA, but it can be done.
Click to expand...

Yep, and even if installed correctly, they usually are noisy.

It would actually be much easier to swap the whole axle, plus you can use your old stuff (shafts, hubs etc...) for spare parts.
 
From what I've read on the intarweb, most people think it's a really bad idea. I had no trouble when I put used 4.10s in my 30/35, however, and they're very quiet. YMMV.
 
CanMan said:
Id suggest not to just take the gears. Setting up used gears can be a PITA, but it can be done. Id just take the whole axle and bolt it in, that way, there is no messing with gears.
Click to expand...

X2
that is exactly what I did, a double axle swap to acheive 4.10 gearing. Zero regrets. axle swapping is easier than setting up gears. good luck.
Cleatus 92
 
Can we get a little more elaborate on why putting used gears in other axles is difficult? I've read that they can settle to one axle and what not, but....wouldn't they settle to the new carrier after time and quiet down?
 
DBenz said:
Can we get a little more elaborate on why putting used gears in other axles is difficult? I've read that they can settle to one axle and what not, but....wouldn't they settle to the new carrier after time and quiet down?
Click to expand...

The reason has to do with basic metalurgy. As gears wear together, the high spots get worn down and everything just kind of fits together better. The problem is that in this wear down and breakin period progresses, the surfaces work harden. When you get done, the surface of the gears is much harder than it was when they were new. If you re-set up gears, you never get them exactly to where they were before, so you are meshing only on the high points. The problem is that the high points are now much harder steel and do not break in the same way that they did when they were new.

I have set up and run several sets of used gears in the past. I've never really had a failure with them but they tend to be a lot more noisy and bug people who ride with you.
 
Say I were to mark where the pinion meets the ring gear with a sharpie while they are in the axle, would that help some, so it may be close to where they originally were? Thank you for the info, that makes much more sense than people jsut saying it won't work.

Derek
 
old_man said:
The reason has to do with basic metalurgy. As gears wear together, the high spots get worn down and everything just kind of fits together better. The problem is that in this wear down and breakin period progresses, the surfaces work harden. When you get done, the surface of the gears is much harder than it was when they were new. If you re-set up gears, you never get them exactly to where they were before, so you are meshing only on the high points. The problem is that the high points are now much harder steel and do not break in the same way that they did when they were new.

I have set up and run several sets of used gears in the past. I've never really had a failure with them but they tend to be a lot more noisy and bug people who ride with you.
Click to expand...

If you replace the original differential with a locker/LSD you will disturb the original setup.
Would you say that when going to a locker you also have to replace the ring and pinion?
Unless you enjoy the noise?
BTW how would you discribe the noise and at what speeds?
 
Its a howling type noise. Some can sound more metallic. Kind of like a power steering pump going bad. It can also sound like a set of TSL's or Boggers humming down the road. Can be on just acceleration or just on deceleration. It can be on both. It can vary in speeds ranging from take off, to freeway speeds. Sometimes it can be just herd from 35 to 45 mph. Sometimes at 40 mph on coast. Other times the noise can occur a freeway speeds. Rare, but might happen when the gears are cold or hot from a long drive. Each situation is different.

You could buy new gears when installing a new full case locker. The pinion will stay the same, all you would have to do is adresse the carrier shims, and possibly the pinion shims, depending on the readout you get.

I have a whine in the 8.25 on deceleration, but I live with it. To each his own I suppose.
 
CanMan said:
Its a howling type noise. Some can sound more metallic. Kind of like a power steering pump going bad. It can also sound like a set of TSL's or Boggers humming down the road. Can be on just acceleration or just on deceleration. It can be on both. It can vary in speeds ranging from take off, to freeway speeds. Sometimes it can be just herd from 35 to 45 mph. Sometimes at 40 mph on coast. Other times the noise can occur a freeway speeds. Rare, but might happen when the gears are cold or hot from a long drive. Each situation is different.

You could buy new gears when installing a new full case locker. The pinion will stay the same, all you would have to do is adresse the carrier shims, and possibly the pinion shims, depending on the readout you get.

I have a whine in the 8.25 on deceleration, but I live with it. To each his own I suppose.
Click to expand...

The reason I am asking is that when I replaced the front diff it started howling between 30-40 mph. The pattern and backlash are all good and I didn't know what to do about it.
I guess the only thing to do is to replace the ring and pinion, which I plan to do sometime in the spring.
 
falcon556 said:
If you replace the original differential with a locker/LSD you will disturb the original setup.
Would you say that when going to a locker you also have to replace the ring and pinion?
Unless you enjoy the noise?
BTW how would you discribe the noise and at what speeds?
Click to expand...
When you remove a carrier you only have to recheck backlash.Pinion depth does not change(which is the set-up).
 
no, you're replacing the carrier, so you would need to check the backlash before and after.
if the backlash after the carrier replacement is the same as what it was before than the gear setup is essentially the same.
 
StylerG said:
is there a set of junkyard axles that are direct replacements that come with 4.10 gears?
Click to expand...


Yes, if you pull axles from an older 4 cyl cherokee.. but you will end up with a dana 35 rear end, so its not the most popular swap.
 
cal said:
Yes, if you pull axles from an older 4 cyl cherokee.. but you will end up with a dana 35 rear end, so its not the most popular swap.
Click to expand...

If it's old enough, you'll get a non-clip D35 which has some advantages. I swapped in a set of 4.10 junkyard axles which cost me $100 (I think gears only would have been $60). I sold the left over shafts on eBay for $140 and dumped the housings in the scrap metal bin. I couldn't get any bidders on the stock 3.07 gears though. Swapping the entire axle is definitely quicker than messing with the gears. Since I was also going spring over on the MJ at the same time, having the extra axle let me do all the welding at my leisure and then do the swap in one afternoon.
 
The only advantage is that when it blows up, you can get strapped off of the trail without having the tire come off. :)

I blew up my non c-clip dana 35 making a u-turn in a dirt field at a trailhead. Granted, I was giving it a good 50% throttle.. but 50% throttle in loose dirt with 32" AT's shouldnt lead to detonation. :)
 
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