Help Me Read My Gear Pattern

adumb · Apr 4, 2015

doing my first gear install and have jumped many hurdles but feel like I am doing the job right and it should be done soon hopefully. I have my backlash set at .009-.010 my preload on my pinion bearing is 17-22 depending on how you read the jumping needle. the only thing that takes a experts eye is the gear pattern. I have printed out a bunch online images but would really appreciate someones opinion on what they think it looks like. hopefully it is good so I can just put it back together and call it a day.

TmanGT · Apr 4, 2015

Where are you doing this? At home? I wanted to do mine but I don't want to if I don't the necessary tools such as a hydraulic press.

TmanGT · Apr 4, 2015

From what I've seen in my research I don't think it's supposed to be that solid looks close though

hoopty5.0 · Apr 4, 2015

Pinion depth might be a hair shallow

adumb · Apr 5, 2015

hoopty5.0 said:
Pinion depth might be a hair shallow

By shallow you mean add some shim to it so that it goes deeper into the ring gear right?

BMW Rider · Apr 5, 2015

Usually measuring pinon depth is done from the back side of the housing so shallower would mean less shim so the pinon sits deeper in. That would be my judgement of your pattern. There is heavy contact at the toe of the drive side and the heel of the coast side. Any time the pattern is opposite from drive to coast sides, you need to adjust pinon depth. Get that right first, then fine tune the backlash.

hoopty5.0 · Apr 5, 2015

BMW Rider said:
Usually measuring pinon depth is done from the back side of the housing so shallower would mean less shim so the pinon sits deeper in. That would be my judgement of your pattern. There is heavy contact at the toe of the drive side and the heel of the coast side. Any time the pattern is opposite from drive to coast sides, you need to adjust pinon depth. Get that right first, then fine tune the backlash.

This is what I was trying to say @adumb. What size shim do you have between the pinion and bearing now? Are you using ford gears?

adumb · Apr 5, 2015

hoopty5.0 said:
This is what I was trying to say @adumb. What size shim do you have between the pinion and bearing now? Are you using ford gears?

They are ford gears. The one thing I never measured was the shim while I was pressing the bearing on the pinion. I used the same shim that was on my old pinion.

The way the old pinion was made it was pretty easy to take the bearing off in one piece. With my new one just by looking at it even with a press it will be hard to get off in one piece with a press. There is no room to get underneath it.

hoopty5.0 · Apr 5, 2015

You shouldn't need to press the pinion bearing on. Heat it up with a torch for 2-3 minutes and it will slide right on. I believe the pinion shim to use is .030. @Boosted92LX may remember. But that should be all you need

hoopty5.0 · Apr 5, 2015

As far as removal, I just cut it off and bought a new one. Costs $20 but saves hours of heartache

Boosted92LX · Apr 5, 2015

adumb said:
They are ford gears. The one thing I never measured was the shim while I was pressing the bearing on the pinion. I used the same shim that was on my old pinion.

The way the old pinion was made it was pretty easy to take the bearing off in one piece. With my new one just by looking at it even with a press it will be hard to get off in one piece with a press. There is no room to get underneath it.

Ok, so to clarify.. the pinion you are installing you want to remove the old bearing and install a new one? Can't give advice if I'm not clear on what we are doing..

The factory uses an .030 shim.. just go to the auto parts store and buy one if you need it, dont bother pulling a bearing unecessarily to aquire a shim. They are cheap.

Also, never put a direct flame on a bearing, it can damage the rollers. If you get bearing matl over 250* F it will stress relieve the steel rollers allowing them to go out of round ruining the bearing and causing failure, very early failure. If all you have is a torch, set the bearing on a steel plate heating gently from underneath using a temp stick to check your temp. A much better method is using an oven set to 240 degrees f. Old school guys I've heard used to hang the bearing in a can of oil on a hotplate to heat it... but that kind of scares me. Sort of a fire hazard.. anyway heat definitely better than pressing, yes.

IF you dont have a bearing splitter you can cut it off as recommended by @hoopty5.0 but it does take finesse. Hoopty is a really good craftsman. If you are not real confident in your ability with powertools you may want to rent a bearing splitter from oreilly or autozone. I picked one up from harborfrieght for 20 bucks I think.

adumb · Apr 5, 2015

thanks for all the help it is much appreciated.

i ended up cutting my newly pressed on bearing so that i can measure the shim. it was stupid of me to not have done that in the first place. I bet you can guess what size the shim was........ .030 so you were dead on about that. i think what i am going to do now is buy two more bearings. one i will grind away the middle a little and make it a slip fit so i can try different pinion shims. the other will be the one i have pressed on once i know which shim i need.

i tried measuring the pinion heads hoping that i would see a slight variance in them that would help me come up with a new shim but measuring them with calipers wasn't yielding me very accurate or repeatable numbers. i am probably going to bring them to work with and get a good measurement of them there.

i am guessing either a .028 or .026 shim will do the trick right?

Boosted92LX · Apr 5, 2015

adumb said:
thanks for all the help it is much appreciated.

i ended up cutting my newly pressed on bearing so that i can measure the shim. it was stupid of me to not have done that in the first place. I bet you can guess what size the shim was........ .030 so you were dead on about that. i think what i am going to do now is buy two more bearings. one i will grind away the middle a little and make it a slip fit so i can try different pinion shims. the other will be the one i have pressed on once i know which shim i need.

i tried measuring the pinion heads hoping that i would see a slight variance in them that would help me come up with a new shim but measuring them with calipers wasn't yielding me very accurate or repeatable numbers. i am probably going to bring them to work with and get a good measurement of them there.

i am guessing either a .028 or .026 shim will do the trick right?

I would use an .028 but not an .026. You really want to stay as close to .030 as possible. .002 wont kill you usually but I wouldn't vary any more.

adumb · Apr 5, 2015

how come you want to stay close to the .030? i thought we would just be looking for the right pattern regardless of what number it takes. does something happen the more you vary from the .030?

Boosted92LX · Apr 5, 2015

See this?

That's the pinion gear out of the car in the background. Note the face of the gear is rough and unmachined? Most companies use the face of the pinion as a reference to set pinion centerline. They are also smooth machine finished. That's what the fancy tools you see in jegs and summit are used for. Ford doesnt do that, otherwise that face would be machined so you could measure it precisely with a depth mic or an indicator jig. Instead, they machine their gears for whatever reason with the backside referenced .030 off the bearing. I don't know why they chose to do this, but every single 8.8 with ford gears I've ever worked on or inquired about was set up this way. If you stray away from ford gears you'll need to set centerline but otherwise stay as close to .030 as you can and you'll be in good shape.

adumb · Apr 9, 2015

My new pics. Backlash is .011-.012. Looks like it isn't as heavy on the heel toe which is what we were looking for. What do you think?

TmanGT · Apr 9, 2015

needs to be between .009-.010 where you are right now your gears will be noisy.

adumb · Apr 10, 2015

Backlash is .010 seems to be on the edge on both sides now.

TmanGT · Apr 10, 2015

I'd run with that

adumb · Apr 11, 2015

Backlash is .012 pinion shim is .034. I think this one is by far the best but I also don't know what I am looking at. I am going to tighten up the backlash and take more pics

Help Me Read My Gear Pattern

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