Considering Rear Differential Pinion Seal Replacement - Alfa Romeo Bulletin Board & Forums
 2Likes
Reply
 
LinkBack Thread Tools Display Modes
post #1 of 19 (permalink) Old 11-23-2016, 11:25 AM Thread Starter
Registered User
Gold Subscriber
 
Join Date: Jul 2016
Location: Magnolia, TX
Posts: 28
Considering Rear Differential Pinion Seal Replacement

Hello,

I've been reading on the BB about replacing the rear diff' pinion seal. I am considering doing the work myself. While I am not a skilled mechanic, I'm handy and this seems like a straight forward job. I am interested in whether or not this is advisable. I don't have a lift and will be doing this in my garage, if i decide to tackle it.

Current condition: the diff' is very wet with lubricant. The car has nominally 50K miles.

From brief discussion w a mechanic and from reading the BB I have gathered the following:

1. the mechanic suggested installing a new pinion nut and torquing to factory spec'
2. another thread talked about using two factory Alfa seals and lubricating w grease the inner side of the outer seal
3. another thread suggested using a Mercedes seal, which had an inner and outer tensioning/sealing spring
4. one thread suggested marking the pinion nut position position and then reinstalling to the same position so that the existing/current preload is maintained

I would like to hear what others would have to say regarding these comments in my particular occasion.

In addition, I'm wondering which fluid should I use?

Thanks in advance,

Brian.

PS--I've got a bunch of questions and will be posting quite a bit and hope not to wear out my welcome!
sonofliberty63 is offline  
Sponsored Links
Advertisement
 
post #2 of 19 (permalink) Old 11-23-2016, 12:11 PM
Registered User
 
GV27's Avatar
 
Join Date: Dec 2004
Location: Lakewood, Colorado
Posts: 1,719
Garage
Send a message via AIM to GV27
Hi Brian,

Welcome to the forum, Brian. You won't wear out your welcome at all if you use these two tips:

1) Post pictures of your car!
2) Utilize the search function.

It is a very straight-forward job but requires a special tool. Centerline sells it - not cheap at all but easily the easiest solution. There are also instructions around here for making your own by grinding down a big socket, or someone around here may be willing to loan you one.

I've only done a couple of them. I've reused the existing nut and installed a single seal. They last OK and it's an easy replacement if you have the tool. I am considering doing the double-seal thing in my project rear-end I'm working on this winter.

As far as the nut goes, it get staked to prevent it from loosening. If this has been done multiple times and the rim is mangled, it might be a good idea to get a new nut. If it's only been staked once at the factory reuse it. I tighten it just past the old stake point so it's tight enough but I have new material to stake down (option #4 in your post). The problem with the factory spec is that it's super-wide (my manual says 57 - 101 ft-lb) and the bottom of the range may be too loose and the top may cause it to bind. If you do some searching you'll find one recommendation of "hand tight, then five hammer blows". You want it snugged up well but not TOO tight.

Oil has been talked about ad-nauseum around here. Whatever you do don't start a new thread about it! Some of our most knowledgeable members are getting extremely testy about it. Really any GL5 gear oil should work though there are considerations if you have an LSD and there are a lot of opinions. The closest thing to a consensus you'll find is Redline 75w/90. Edit: ah, you have a '90 as well. It has an LSD.

This thread has a bunch of info to get you started: http://www.alfabb.com/bb/forums/spid...l-process.html

Chris

1990 Spider Veloce

Last edited by GV27; 11-23-2016 at 12:35 PM.
GV27 is online now  
post #3 of 19 (permalink) Old 11-23-2016, 12:40 PM
Richard Jemison
Platinum Subscriber
 
Alfar7's Avatar
 
Join Date: Apr 2005
Location: Pensacola, Fl. U.S.A.
Posts: 6,987
Lubricant

Correct lube is Redline 75-90 NS (not Redline 75-90)

You won`t be able to torque it without the correct socket, but excessive torque isn`t necessary.
You should use Red Locktite on the nut when installing.

We have changed these at the track using a hammer & drift to un-do and tighten the nut.

FYI: Preload on this unit is determined by the shim pack inside the unit, and not by "Torque to a measured preload" of the bearings.

Richard Jemison
RJR Racing

To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.

"When you are dead you don`t know it.
Only those around you are distressed.
Same with stupid"

Last edited by Alfar7; 11-23-2016 at 05:14 PM.
Alfar7 is online now  
Sponsored Links
Advertisement
 
post #4 of 19 (permalink) Old 11-23-2016, 01:05 PM
Quote:
Originally Posted by Alfar7 View Post
...FYI: Preload on this unit is determined by the shim pack inside the unit, and not by "Torque to a measured preload of the bearings.
And that's why the torque spec is so wide - if you are outside of that range there is something amiss with the shim pack...

I adhere to the "mark it and then tighten it back to the mark" or a little past procedure. But you need to count the number of revolutions as you remove it too.
gprocket is offline  
post #5 of 19 (permalink) Old 11-23-2016, 01:43 PM
Registered User
 
GV27's Avatar
 
Join Date: Dec 2004
Location: Lakewood, Colorado
Posts: 1,719
Garage
Send a message via AIM to GV27
Really better advice is to never mention differential and transmission oil at all on this forum. No matter what you say it pisses someone off.

Chris

1990 Spider Veloce
GV27 is online now  
post #6 of 19 (permalink) Old 11-23-2016, 02:38 PM
Senior Member
Gold Subscriber
 
Norseman50's Avatar
 
Join Date: Apr 2014
Location: Bellevue, WA
Posts: 1,447
Garage
Quote:
Originally Posted by sonofliberty63 View Post
1. the mechanic suggested installing a new pinion nut and torquing to factory spec'
Yes and no. Use a new pinion nut if you like, but don't torque it to factory specifications. That could alter the existing pre-load.
Quote:
Originally Posted by sonofliberty63 View Post
2. another thread talked about using two factory Alfa seals and lubricating w grease the inner side of the outer seal
The use of two seals is not really necessary IMO.
Quote:
Originally Posted by sonofliberty63 View Post
3. another thread suggested using a Mercedes seal, which had an inner and outer tensioning/sealing spring
I have no experience with, or knowledge about, the use of a Mercedes seal as a substitute, since the correct Alfa one is readily available.
Quote:
Originally Posted by sonofliberty63 View Post
4. one thread suggested marking the pinion nut position and then reinstalling to the same position so that the existing/current preload is maintained
This is an absolute MUST. Mark the pinion nut clock position, in relation to the flange, prior to loosening. Then count the number of revolutions it takes to get the nut off. When re-installing the pinion nut, screw it in the same number of turns and then stake it. This will ensure the same preload is maintained.
Quote:
Originally Posted by sonofliberty63 View Post
In addition, I'm wondering which fluid should I use?
Redline 75W90

One other bit of advice. It's quite easy for the pinion splines to weep or leak fluid, directly onto (and past) the pinion nut. So to ensure I don't still have leaking after replacing the seal (I hate doing a job twice), I like to apply a thin bead of Permatex Hi Temp Thread Sealant onto the pinion splines right before I slide the pinion flange on.

Best of luck,
Attached Images
  

Edward
'88 Quad - "Claudia"
Norseman50 is offline  
post #7 of 19 (permalink) Old 11-23-2016, 02:52 PM Thread Starter
Registered User
Gold Subscriber
 
Join Date: Jul 2016
Location: Magnolia, TX
Posts: 28
I have purchased Brock Nanson's car. Very smooth transaction. He was great to deal with.
Attached Images
 
sonofliberty63 is offline  
post #8 of 19 (permalink) Old 11-23-2016, 02:57 PM
Registered User
 
GV27's Avatar
 
Join Date: Dec 2004
Location: Lakewood, Colorado
Posts: 1,719
Garage
Send a message via AIM to GV27
Purdy!

Chris

1990 Spider Veloce
GV27 is online now  
post #9 of 19 (permalink) Old 11-23-2016, 03:03 PM
Senior Member
Gold Subscriber
 
Norseman50's Avatar
 
Join Date: Apr 2014
Location: Bellevue, WA
Posts: 1,447
Garage
Removal of old seal

It's not always easy to get the old seal out, especially if you want to avoid scarring the I.D. of the differential's aluminum casing bore. So to be safe, and employ a minimum of energy, I use a combination of lag bolts and pieces from a harmonic balancer/wheel puller kit.

I predrill holes for the sheet metal screws in the metal frame of the old seal, taking care not to go too deep or too close to the edge. You don't want to punch through the seal and damage the bearing underneath with the drill bit, or allow the bolts to scar the bore walls.

Then I add some washers to the lag bolts and thread them through the slots in the puller spider.

Finally I apply some torque to the puller bolt and the seal slowly slides out.
Attached Images
     

Edward
'88 Quad - "Claudia"
Norseman50 is offline  
post #10 of 19 (permalink) Old 11-23-2016, 03:19 PM
Registered User
 
BostonBertone's Avatar
 
Join Date: Dec 2012
Location: Boston
Posts: 949
This is a fairly easy job. All the advice above is good. I used Redline 75W90 NS. The NS is important for LSDs. While I have a 68' the axle is from an 88'. There are two seals available get the right one - again depends on LSD.

I made my own tool per the instructions. If you have a cutoff wheel it is not hard to make. It can also be carefully done with a punch as mentioned. I've also seen leaks occur at the diff pan gasket. If you have it drained I'd consider refreshing that as well. I hate oil leaks and have almost managed to address them all.
Norseman50 likes this.

68' Parisian Alfa GTV 1750
BostonBertone is offline  
post #11 of 19 (permalink) Old 11-23-2016, 05:32 PM Thread Starter
Registered User
Gold Subscriber
 
Join Date: Jul 2016
Location: Magnolia, TX
Posts: 28
Thanks to all for the kind words and help! I'm very excited about the car and appreciate all of the comments and guidance!

Best regards,

Brian.
sonofliberty63 is offline  
post #12 of 19 (permalink) Old 11-23-2016, 10:49 PM
PSk
Registered User
 
Join Date: May 2003
Location: Tauranga New Zealand
Posts: 11,413
Send a message via AIM to PSk Send a message via Yahoo to PSk
Quote:
Originally Posted by Norseman50 View Post
Yes and no. Use a new pinion nut if you like, but don't torque it to factory specifications. That could alter the existing pre-load.
As Alfar7 said the torque on the nut does NOT alter the pinion bearing pre-load. Alfa Nord diffs use solid spacers + shims to set pre-load. Only if the design used a collapsible spacer would the pinion nut torque affect the pinion bearing pre-load (think BMW 2002 and Ford Escort, etc.).

Any diff I rebuild always uses solid spacers, even if that means I have to jump on a lathe and make the spacer as I did for my club race car that used a Ford Escort rear axle. It is the proper way to set up a diff pinion IMO.
Pete

'71 1750 Series 2 GTV:
To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.
156 Series 1 v6 ... and remember it's all just opinions
To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.

Last edited by PSk; 11-23-2016 at 10:51 PM.
PSk is offline  
post #13 of 19 (permalink) Old 11-24-2016, 06:50 AM Thread Starter
Registered User
Gold Subscriber
 
Join Date: Jul 2016
Location: Magnolia, TX
Posts: 28
Question regarding installing two seals, option 2 above. I'm wondering if this is something I should do. As noted, this was something mentioned in one of the threads on the topic.

First, is there much benefit to doing this? Seems like cheap insurance.

The main downside that I see is that I couldn't use the return the pinion nut to the original position method for setting preload. Option 4. from above "one thread suggested marking the pinion nut position and then reinstalling to the same position so that the existing/current preload is maintained"

Again, thanks to all for the detailed explanations and notes. I understand from this thread and others, that the pinion bearing preload is set by shims, etc. So one last question, is what is being loaded by tightening the pinion nut? Seems like the seal to housing.

Thanks again for all the information and Happy Thanksgiving to all!

Brian.
sonofliberty63 is offline  
post #14 of 19 (permalink) Old 11-24-2016, 08:42 AM
Richard Jemison
Platinum Subscriber
 
Alfar7's Avatar
 
Join Date: Apr 2005
Location: Pensacola, Fl. U.S.A.
Posts: 6,987
Seals

There is no reason using 2 seals will cause a spacing issue or change in the position of the nut when tight.
Forget the word "preload" as tightening the nut has nothing to do with pinion preload in these diffs. You only have to get the nut tight. The red locktite will keep it tight and prevent leakage weeping past the threads into the cavity around the nut and u-joint.

Removing the seal is simple. Use a screwdriver to distort the seal housing around its circle. Then it can easily be removed as the side lip is distorted and free to move.

Richard Jemison
RJR Racing

To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.

"When you are dead you don`t know it.
Only those around you are distressed.
Same with stupid"
Alfar7 is online now  
post #15 of 19 (permalink) Old 11-24-2016, 08:50 AM
Trained (ex)Professional

1953-2018 RIP

Platinum SubscriberAdministrator
 
papajam's Avatar
 
Join Date: Feb 2003
Location: New Jersey USA
Posts: 16,232
I use a Snap-On seal puller (for more than just pinion seals).
Attached Images
 
Top Down likes this.

Jim

Series 2 USA 1750 GTV (in Series 1 European clothing)
papajam is offline  
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Alfa Romeo Bulletin Board & Forums forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in










Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

 
For the best viewing experience please update your browser to Google Chrome