Rebuilt Diff noise

[Malicious]

Hi All,

Just rebuilt a used highway diff for my coronet, and put it in on the weekend. I took it for about a 150km round trip to a car show.

On first use it was noisy; some on accel, but mostly on deceleration. after a bit of driving it quietened down a lot but there is still some very slight noise on drive and almost a whine on deceleration.

I found that when assembled the pinion was tight and adjusting the preload spacer with shims really didn't make a difference until it slacked off enough to have side movement. SO I built it to the tightest tolerance before it got side movement, although it was still not as free spinning as the other one I recently rebuilt. assembled etc and threw it in.

Just wondering if people think this should clear up after a bit more bedding or if the used gears are on the way out? or have I screwed something?

One last thing, its an open center and I ran the SAE 90 - GL5 LSD gear oil, no additive. Could this be part of the issue?

Cheers

 

[bm02tj]

Used gears need to be set up exactly as they where or not they will be noisy if your pattern is perfect and you can live with the noise drive it as it may diminish if not new ones

 

[Malicious]

I thought that might be the case, but I wanted to check with the Forum. I can live with the noise, not that bad, as long as it doesn't grenade on me!

 

[mentor70]

i just did a ford 9 for my PU, the gears were US gear, and only like 300-400 miles, the guy i got them from said they were noisy on decel too, but he put it together with China made parts.

so i redid this one with a different case, Timken bearings and new shims. i set the pinion preload at 15 in lbs of drag, and then set the back lash at 11ish. i play with the pinion depth shims until a got a decent pattern and im happy, not much noise at all.

did you replace the pinion bearings at all?
if so, and you were a little tight, yeah it will loosen up a little.

 

[Malicious]

Yeah all new timkins from Cass. I got a good pattern, much happier with this over the last, but it was just heavy on the pinion drag. I have another big drive this weekend, so I'll pack the old 4.56 just in case, but hopefully it will loosen up a touch over the run.

 

[dvw]

Are you saying you removed all pinion preload until it had side play?
Doug

 

[Yatzee]

Hi All,

Just rebuilt a used highway diff for my coronet, and put it in on the weekend. I took it for about a 150km round trip to a car show.

On first use it was noisy; some on accel, but mostly on deceleration. after a bit of driving it quietened down a lot but there is still some very slight noise on drive and almost a whine on deceleration.

I found that when assembled the pinion was tight and adjusting the preload spacer with shims really didn't make a difference until it slacked off enough to have side movement. SO I built it to the tightest tolerance before it got side movement, although it was still not as free spinning as the other one I recently rebuilt. assembled etc and threw it in.

Just wondering if people think this should clear up after a bit more bedding or if the used gears are on the way out? or have I screwed something?

One last thing, its an open center and I ran the SAE 90 - GL5 LSD gear oil, no additive. Could this be part of the issue?

Cheers

It won't go away so it's time to readjust the pinion depth and side gear. It's a bitch to do but when you clean and paint the gear you'll see the error of your ways. Be patient. Took 4 1/2 hours just to set up my diff. I used shims instead of a collapsible sleeve to get the proper depth and preload on the pinion, the rest of the adjusment was strictly using gear marker.

 

[Malicious]

Are you saying you removed all pinion preload until it had side play?
Doug

So I have a couple of shims under the larger pinion bearing at the gear head to set the depth of the pinion on gear correctly, got a good placement of contact there. But the shims on top of the solid preload spacer was what I was talking about specifically. I have three on there, a forth gave me side to side play on the yoke, three got rid of all the side play but the was a decent amount of drag on it when spun.

 

[Malicious]

It won't go away so it's time to readjust the pinion depth and side gear. It's a bitch to do but when you clean and paint the gear you'll see the error of your ways. Be patient. Took 4 1/2 hours just to set up my diff. I used shims instead of a collapsible sleeve to get the proper depth and preload on the pinion, the rest of the adjustment was strictly using gear marker.

Yeah I didn't rush it, it all went well, pattern was better than the first even (both used gears). the only thing that was different was the extra drag on the pinion and now the noise when being used. I'm going to double check the end play on the axles tomorrow morning as well. But it actually went together well except those two points.

 

[dvw]

So I have a couple of shims under the larger pinion bearing at the gear head to set the depth of the pinion on gear correctly, got a good placement of contact there. But the shims on top of the solid preload spacer was what I was talking about specifically. I have three on there, a forth gave me side to side play on the yoke, three got rid of all the side play but the was a decent amount of drag on it when spun.

You add/subtract the preload shims (small ones) until the correct turning torque is obtained. Did you use a in/lb torque wrench? I've done enough to get close by feel myself , but I still check them. It may not have enough pinion preload. How did you load the side bearings? Or you are correct. It could be used gears.
Doug

 

[Malicious]

You add/subtract the preload shims (small ones) until the correct turning torque is obtained. Did you use a in/lb torque wrench? I've done enough to get close by feel myself , but I still check them. It may not have enough pinion preload. How did you load the side bearings? Or you are correct. It could be used gears.
Doug

Which part did I use the correct torque wrench for? Tightening the pinion nut? I just tightened that as hard as I could, based on it being a solid preload spacer... should it have been torqued to a certain spec even with a solid spacer? I had messed around with a few combinations on the preload shims, seamed like the best was three shims as mentioned.

As for the loading the side bearings, I found the tightest part of the crown/pinion mesh, adjusted the side nuts until I got a good pattern, then torqued until I got the right backlash on the dial indicator at that tightest mesh point. I lock the pinion yoke to the table I'm working on when checking the backlash, and just rock the crown back and forward.

Does that sound right or am I missing something?

 

[dvw]

set pinion depth. Shim preload bearings. Check by rotating the pinion with the in/lb torque wrench. 15-20in/lb. Set the backlash then zero, then tighten the right side adjuster to obtain .006-.009" backlash

 

[Cranky]

Setting up used gears can be hit or miss but being noisy on decel usually indicates the pinion is too deep. How loud are they? Quiet enough that a couple of people can talk normally while driving and the noise isn't above the conversation?