Howling on deceleration after changing pinion seal
Thread Starter
Intermediate
Joined: Feb 2018
Posts: 49
Likes: 14
From: Lugoff South Carolina
Howling on deceleration after changing pinion seal
I changed the pinion seal on my '79 this weekend and now I have kind of a howling noise on deceleration. I marked everything and counted how many turns it took to remove the pinion nut. When I went to put it back together the mark on the nut was gone so I counted the turns when I put it back on to get it as close as I could. I've done a lot of searching and it seems like noise on deceleration means the pinion bearing preload has loosened, does this mean that I need to tighten the nut more or is it too tight?
Last edited by L-82 4Speed; Aug 5, 2019 at 05:45 PM.
Racer
Joined: Oct 2017
Posts: 312
Likes: 64
From: Henry county ohio
This is just my opinion, and this is what I have done with my own stuff.
Sounds to me like the nut isn't tight enough to set the bearing preload.
There are a few ways to check, and each one gets more and more involved.
1. Disconnect the drive shaft at the pinion and see how much in and out play you have by hand, if the pinion has any feelable movement, tighten the nut just a touch more. A little nut turning goes along way.
2. Measuring with a magnetic base dial indicator.
Measure the in and out play, tighten the nut a tick. Re-measure, repeat until there is no change in your measurement. That would indicate that the bearing races are up against the crush sleeve.
3. Disconnect the half shafts also. Then using a dial torque o meter, tighten the pinion nut untill it takes about 5 in/lbs to turn the pinion.
May want to look at a manual for the correct rotatonal torque, I'm pulling this either from memory, or my a$$, don't know which. Lol
Option one is caveman, but if you have a feel for this kind of thing, works-ok.
Number two is more precise.
Three is probably best practice.
Don't forget to stake the nut.
As usual ymmv,
Good luck
Jeff
Sounds to me like the nut isn't tight enough to set the bearing preload.
There are a few ways to check, and each one gets more and more involved.
1. Disconnect the drive shaft at the pinion and see how much in and out play you have by hand, if the pinion has any feelable movement, tighten the nut just a touch more. A little nut turning goes along way.
2. Measuring with a magnetic base dial indicator.
Measure the in and out play, tighten the nut a tick. Re-measure, repeat until there is no change in your measurement. That would indicate that the bearing races are up against the crush sleeve.
3. Disconnect the half shafts also. Then using a dial torque o meter, tighten the pinion nut untill it takes about 5 in/lbs to turn the pinion.
May want to look at a manual for the correct rotatonal torque, I'm pulling this either from memory, or my a$$, don't know which. Lol
Option one is caveman, but if you have a feel for this kind of thing, works-ok.
Number two is more precise.
Three is probably best practice.
Don't forget to stake the nut.
As usual ymmv,
Good luck
Jeff
Tech Contributor
Joined: Aug 1999
Posts: 15,193
Likes: 4,016
From: Connecticut, USA
There should be no in/out movement on the pinion, if you feel it then you are correct you didn't tighten it enough. Now you have to watch it if you are using an impact gun as you can over-crush the sleeve and tighten the bearings too much and they will start to give you problems.
If you lost your marks and don't have a 0-30 in/lb dial TW you can back the nut off and bring it in until you feel it seat on the sleeve. Now if you are not sure of the correct "feel" this may be difficult to do and I feel this is shooting in the dark so to speak. If the yoke was moving around you may also wreck your new seal and have to start over. If the pinion is loose enough it will crash into the posi case on acceleration, which you will hear in most cases. When I open a diff and see the pinion marks on the posi case, whether light or deep I know the pinion seal will most likely not be the original green ones GM used, could be a CR/SKF seal but most times are red or orange.
There is another thread running here now on this same subject. I posted a link to pictures that will help you.
If you lost your marks and don't have a 0-30 in/lb dial TW you can back the nut off and bring it in until you feel it seat on the sleeve. Now if you are not sure of the correct "feel" this may be difficult to do and I feel this is shooting in the dark so to speak. If the yoke was moving around you may also wreck your new seal and have to start over. If the pinion is loose enough it will crash into the posi case on acceleration, which you will hear in most cases. When I open a diff and see the pinion marks on the posi case, whether light or deep I know the pinion seal will most likely not be the original green ones GM used, could be a CR/SKF seal but most times are red or orange.
There is another thread running here now on this same subject. I posted a link to pictures that will help you.
Last edited by GTR1999; Aug 7, 2019 at 07:12 AM.
