vbMike

iTrader: (2)

Get ready for a stupid question. I’m in the middle of swapping axel gears. Going from 3.27 to 3.70. Anyway, what can I spay inside the differential to clean the oil off the ring/pinion/housing? I don’t want to use something that would cause the gears to rust or leave a residue. I want to check the pattern on the ring gear before I dissemble it so I have something to compare with the new ring when I install it. I’m using gear marking compound but am having some difficult trying to get a good mark. I tried setting the parking break to create a load which helped some. Any advice?

big gear head

Brake cleaner works great.

It's a waste of time to check the pattern on used gears. The pattern will not look like it is suppose to because of wear on the gears. They only reason you would want to check the pattern on used gears is if you were going to reinstall them and you needed something to go by. The new gears will have a completely different looking pattern on them. If you just want to check it anyway then use the axle to turn the differential instead of turning the drive shaft. Have someone lay their hand on the drive shaft to put a slight load on it.

91 1LE

iTrader: (1)

You can use brake or carb cleaner to clean the inside of the housing. Just let it all evaporate before reassembly.

I H8 WWD

iTrader: (5)

Brake Cleaner is my friend

vbMike

iTrader: (2)

I figured brake cleaner would work well. Thanks.

So you're saying that the pattern on used gears are going to look different than new gears. I don't understand why that would be the case. Anyway, the gears I am putting in are used not new. Is that going to cause a problem when I go to check the pattern?

big gear head

Used gears are more difficult to set up because of the wear. A new gear doesn't have wear on it and the contact area is smooth and flat. A used gear is going to have a little wear where the gears contact and it will have a slight dip in this area. When you check the pattern the gears will not fully contact in this area and the pattern will not look like it should. I usually go more by the pattern on the coast side than the drive side when setting up used gears. The coast side has much less wear on it and the pattern shows better.

vbMike

iTrader: (2)

That makes sense. Thanks for the explanation. I did notice that I getting a better pattern on the cost side rather than the drive side. What do you recommend for correctly setting the pinion depth? Use the factory spacer and just read the pattern?

l_dis_travlr

The idea of coast-side pattern...

In a previous life, I set pinion depth as part of the adjustment to get the
correct pattern. The drawback is pressing on & off the pinion bearing to
change shims -- which, without a press in my garage, would mean multiple
trips to a commercial shop. Rube Goldberg that I am, I got the old bearing
removed, and then spent enough time with a rotary grinder, so that it
was easy to slip on/off. Got the shims set for the pattern I wanted, and
then had a new bearing pressed on. Re-checking, the pattern was still good.
Performance was smooth & quiet.

Good luck, & let us know how it turns out.

kk

vbMike

iTrader: (2)

So you just use the pattern to adjust the pinion depth. That's what I'm going to do unless I hear of a better method. I've heard of the + - method but that only works when swapping from one set of factory gears to another. My gears are aftermarket.

I am also familiar with your bearing tip. However, I have a 9 bolt and I believe the spacer is between the race and the housing. So I should be able to press on the bearing and then change the spacer by removing the race. However, I'm not sure if the race can be easily removed without damage.

big gear head

The pattern should always be used to set the pinion depth. Even if you use a pinion depth gauge, you still make the final adjustment by reading the pattern and correcting the shim thickness.

l_dis_travlr

It was pressed in as a servicable unit, it can be taken out.
Look for some indents in the case, where a punch could be
JUDICIOUSLY applied.

And then when you have the race out, grind on the outside
instead of the inside. A bench grinder would be easier than
a drill/rotary file, but the principle is the same. Afterwards,
the old race can be used to JUDICIOUSLY tap in the new
race.

Good luck,
kk

vbMike

iTrader: (2)

Can I use the original race and grind it down so it slips in/out easily to setup the pinion and then replace it with the new race from the new bearing once the depth is set. I'm just wondering if I hammer in the new race if I can get it out without it being damaged if I need to change the shim.

big gear head

The 9 bolt rear ends that I have put together (3) had the shim behind the bearing on the pinion gear. If you shim it behind the race you will be able to drive it out without damage.

vbMike

iTrader: (2)

Funny that you say that. I thinks I've heard other say the same thing. I have the factory shop manual for the 9 bolt and it says the spacer is supposed to be behind the race. Weird.

Would it be okay to move the spacer behind the race? It seems like it would be easier to make changes.

big gear head

It doesn't matter if you shim it behind the bearing or race. Dana rear ends are shimmed behind the race and most GM rear ends are shimmed behind the bearing.