9.25 ZF 4.56 gear Set Up question

Raven · Jun 11, 2017

Hi guys. I ordered a 4.56 ring and pinion kit from Moe's, with a Mopar LSD, and had a shop I have trusted for years install it for me. Unfortunately, I believe after driving it a couple times it is making more noise than it should. After doing a lot of research I am being led to believe the backlash is too loose.

I will be going to tomorrow to measure the back lash and check the contact pattern myself, but I have had it back at the shop and they are positive it is all within spec. I have read that sometimes if it is set to the higher end of spec around .0010" they howl pretty loud which is what I am experiencing. It's just too loud and constant at varying speeds for me to think it's fine.

I am pretty handy mechanically, but I haven't touched a diff myself. I have a dial indicator and the marking compound, is adjusting it without pulling the carrier all the way back out feasible? Can anyone walk me through the process, or point me to a DIY? Pulling the axles out as we speak so it will be ready to go tomorrow.

Greatly appreciated, and will take any feedback you have. I would just take to another shop, but I don't know of any with a lot of ZF axle experience and would really like to learn more about it.

Pat

whetrick1 · Jun 11, 2017

I am not an expert on diff's but I don't think you can make adjustments without pulling the carrier.

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kg93 · Jun 11, 2017

4.56 will always be louder. That being said my first set of 4.56 whined real bad and I had to get another set, these are much more quiet.

Wild one · Jun 11, 2017

You need the special tool to adjust the back lash.Basically it's a long rod with a big nut on the end,to access the carrier adjusters.2 things can cause noise,most common is backlash out of adjustment,but another issue that can cause noise,is new bearings installed into old bearing races,both can cause noise.Before you take it apart make sure you have the adjuster tool on hand,as you can't do anything with-out it.Kurtis /Charonblk has our adjuster tool at his place,but he's still in the bush working,so getting a pic of it for you is out.

Raven · Jun 11, 2017

I am almost positive the noise isn't bearings. I have had bad bearings before, and this just doesn't sound quite the same.

Thanks for the heads up - I am going to try and borrow the adjuster from the shop tomorrow when they open hopefully. I have read instructions for a old style 9.25, but can anyone please tell me what the adjustment procedure would be for the ZF axle?

Ram Night · Jun 11, 2017

If your pinion ring gear backlash is over .006 to .008 you will need a special tool that will reach the differential side bearing adjusters through the axle tube after you pull the axles. I made mine out of a 3 foot long piece of 1" pipe with a 1"to 1-1/4" adapter that will go into the adjuster. Then loosen the bolts that hold the bearing caps on and torque them to 25 ft/lbs, then remove the locking tab bolts that keep the end caps from turning. From there tighten or loosen each adjuster until you have the proper backlash, when both side adjusters are torqued to 68 ft/lbs. This will take a little time but you will get it. Then torque the side bearing caps to 100 ft/lbs. I just Installed a Limited slip differential in my Rebel two months ago, and it took about 4 hours.
As long as you are into the gears, see if you can get a little yellow gear marking paint, and make sure the ring gear is running in the center of the tow and heal ends of the ring gear. If you put thee transfer case in neutral, you will be able to turn the pinion gear without pulling the drive shaft.

9.25 ZF 4.56 gear Set Up question

Raven

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whetrick1

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kg93

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Wild one

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Raven

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Ram Night

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