vbMike

iTrader: (2)

I need to know how to adjust ring gear run out but please read the entire post. I’m in the process of swapping gears in my 9 bolt. I had 3.27 and am putting in a USED set of 3.70. I put the pinion in using the stock shim. I put the carrier back in and adjusted the side shims and torqued down the bearing caps. I’m checking the backlash and noticed that when I rotate the pinion it rotates freely and then binds up at the same place on the ring gear each time I rotate it. When I check the backlash at the tight point I obviously get 0.000 I then rotate the ring gear 180* and recheck and get the desired 0.006 So the ring gear has a wobble or run out. I check the run out which is supposed to be a max of .005 and I am getting .015. My stock gear was .003 before I removed it. Why am I getting so much run out and how do I adjust it???

Here is the only thing that comes to my mind. I took the pinion to a shop to get the bearings pressed on. I also had the change the ring gear because I didn’t have a vice to hold it. Once done I asked him what he torqued the ring gear bolts down to and he said that he tightened them with an impact gun until they were tight and didn’t use a torque wretch and gave me attitude for asking him. So if the ring gear bolts are not torqued evenly would this be causing the run out?????

Someone please help…

big gear head

Sounds like you might have got screwed. You need to take the ring gear back off of and check the run out on the flange. He might have bent it when he used the impact to tighten the bolts. He also might have got a burr under the gear by not pulling the gear on evenly. Any way it goes, you are going to have to remove the gear to check it out. There is no way to adjust run out. You have to fix the problem. If the flange is bent then you might have to replace the differential. Don't put it in a vice to tighten the bolts. Put an axle in a wheel and stand it up on the floor. Put the differential on it and use that to hold it while you torque the bolts. With the 9 bolt you need to put the other axle in to keep the splines aligned.

vbMike

iTrader: (2)

Thanks for the reply. Okay, I’ll remove the ring gear and check the run out on the flange. Good advice. I’ll be pissed if they bent it.

Why would it be bad to put the carrier in a vice? I like your suggestion about using the axel to hold the carrier to remove the ring gear bolts. If I stand on the tire do you thing that will be enough weight to prevent the tire from rotating on the ground while I loosen the bolts? I understand what you’re saying about the spines in the 9 bolt but I thought that was only necessary to have both axels in place when reassembling the differential. The spine alignment won’t change if I don’t take the case apart will it?

big gear head

If the clutch slips a little while you are loosening or tightening the bolts then the gear on the other side will move and the splines will be out of alignment. I would remove the bolts with an impact if you have one. If not then standing on the tire will work.

vbMike

iTrader: (2)

Okay I found the problem. The ring gear bolts were not tight at all. They were probably only around 35 ft/lbs. I took the ring off and check the run out on the carrier and it was around 0.003 so everything checked out there. I cleaned both the ring gear and carrier up and bolted the ring back on torquing to around 80 ft/lbs. Not sure if I can get it any tighter without the tire spinning on the floor. Anyway I check the run out on the ring and it was around 0.004 so everything looks good now.

I can't believe the guy gave me attitude when I asked him what he torque the bolts to. This guy was going on and on about how he had been setting up differentials for 20 years and does it every day and then after he finished his rant tells me that he just tightened the bolts using the impact wrench and no torque wrench. Then I get home just to find out that the bolts weren't even tight. No harm done but geese.

vbMike

iTrader: (2)

So I used the stock shim under the pinion and set the back lash to 0.006. Here is the pattern that I’m getting. Does this look acceptable? I have my own thought but wanted another opinion. I had a hard time a good pattern so any tips are appreciated.

The pattern seems centered on the face on the drive and coast side. The pattern is close to the heal on the coast side and close to the toe on the drive side. Keep in mind these are used gears so the pattern on the drive side might be meaningless even though it seems to show up better than the coast side did.

big gear head

Here are a few suggestions. First, increase the backlash to .010. A used gear shouldn't have .006 backlash. It's all right on a new gear. Next, use an axle to turn the differential with the gear marking compound on it. If the pinion bearing preload is tight enough then turning the differential with an axle will give a better looking pattern. You need to make a few more rounds with this one to wipe off a little more of the compound. The coast side looks like the pinion is a little deep. You might take a little out of the pinion shim. Maybe .003 to start with.

vbMike

iTrader: (2)

Thanks once again for the reply. I had a couple thoughts and questions.

1. I assume that you want me to increase the back lash because the gears are used and have already been broke it. In other words a new gear set should be 0.006 because as the gears break in the backlash will increase and since my gears are used I should increase the back lash. It seems to make sense but I checked the back lash on my stock gears before I removed them and they were around 0.006 or slightly less. So if the backlash doesn’t seem change as the gears wear in shouldn’t I still set these to 0.006?

2. When I rotate the ring should I go in both forward and reverse direction or forward only? I rotated the pinion by hand and used a wrench on the ring gear bolt to create resistance. I don’t see why using an axel to rotate the carrier would help but I can try it.

3. When you say the coast side looks to deep you mean that the pinion is too close to the ring correct?

4. I’ve heard conflicting information about adjust the pattern so maybe you can clarify. One article said to adjust to obtain a center pattern on the face (depth) and ignore the heal to toe pattern. The reasoning was that a pattern centered on the face (Depth of the tooth) was more important than a pattern that was centered from toe to heal and that the two locations can not be adjusted independently.

Another article stated that the pattern should be perfectly centered on the tooth in all directions. They stated that the pinion depth controls the toe to heal alignment and the backlash controls the alignment on the face of the tooth from top to bottom on the short side. So who is correct?

big gear head

If the backlash was .006 before you removed it then set it to .006.

Rotate the ring gear in both directions. Don't just move it back and forth in the same location, make several full rotations in both directions. It is easier to get clear markings when you use an axle to turn the differential. When turning the pinion the markings will not be as clear and it makes it harder to read. When I started building rear ends around 20 + years ago I turned the pinion too. Then I realized that turning the differential would make the pattern easier to read.

Yes, the pinion is too far into the ring gear. Move it out slightly by using a pinion shim that is about .003 thinner.

Root to face is the most important thing to get correct. If it is offset to the heel or toe then you might have to live with it. Most quality gears will give a pattern that is centered both root to face and heel to toe. With a used gear you might have to be happy with root to face. Make your judgements more off of the coast side because it will have much less wear on it.

vbMike

iTrader: (2)

Okay I may have another problem. I bought my install kit from Ratech. The bearings I receive seem to be correct but I’m not sure about the shims. I got one of their solid pinion spacers. The small shims that came with it seem to be the perfect size but the larger spacer seems too big for the pinion. In picture 1 you can see there is a lot of space between the shim and the pinion shaft. Almost to the point that it may slip over the smaller shims under it. Is it supposed to be this way? I just thought it would fit the pinion tighter.

The kit came with two different size shims. One for the carrier and the other for the pinion or so I thought. In picture 2 you can see the shim I removed from behind the pinion bearing race is much larger than the shim in the kit. Picture 3 show the stock pinion shim again with what I though was supposed to be a carrier shim and appears to be closer in size. The outside of the shim is just a little smaller but the inside is much smaller. I think it would work but I’m not sure.

The 4th picture shows the factory carrier shim with the replacement carrier shim. Again the outside diameter is a little smaller but the inside diameter is again a lot smaller. The axel fits though the shim so I don’t know if that matters or not.

So basically the pinion spacer seems sloppy, I have 4 small size shims that don’t appear to go anywhere and a whole bunch of bigger shims that appear that they would work for both the pinion and the carrier.

Do these parts look right to you???

vbMike

iTrader: (2)

Had to create another reply to post the 4th picture

big gear head

I wish I had known that you were going to get a Ratech kit. I would have tried to stop you. They are probably the worst kits available. I will not use one. The kits from DTS, Tom's Differentials and Randy's Ring & Pinion are much better. I don't know what to tell you except get a better kit. I know that doesn't help you now.

vbMike

iTrader: (2)

Yea I had bought that install kit a while ago. I though I had read that it was supposed to be one of the better kits so I bought it but I'm rather disappointed now. If they'll let me return it I will and buy one of the kits you recommended.