Do I need to check backlash after replacing the diff bearing?

* wrote:
> wrote in article
> >...
>> * wrote:
>>> aarcuda69062 > wrote in article
>>> >...
>>>
>>>> The factory shims that are in there now are cast iron, they'll
>>>> break if you try to reinstall them.
>>>>
>>>
>>> .....only if you try to install them with a hammer and without using
> the
>>> correct housing spreader.
>>>
>>> If you spread the center section correctly, they will drop right
>>> in......just like at the factory.
>> Nice to know, but unfortunately I don't have a "housing spreader", is
>> that thing really necessary?
>>
>
> Some people would say "no", but I bought one because I was doing a number
> of Spicer-type rears, and I DO believe they are necessary - especially if
> you are setting up a new set of gears.
>
> You must often install and remove the shims several times to get things
> right.

I assumed that wasn't necessary since I'm not replacing the gears.

Anyway, I've removed the differential case from the car and the
differential bearings look alright, the problem appears to be the thrust
washers on the side gears. I can move both spider gears about 5mm / .2"
left and right which I assume is too much play. This would be why
there's play in the drive axles and the noise I've been hearing on left
turns would be the left brake disc touching the holder of the caliper.
Unfortunately, I don't have any new thrust washers, so I'm at a dead
end. There doesn't appear to be any point of replacing the bearing
either if it's good.

The question remains whether I should try to put everything back
together or just walk in with the diff to the mechanic. Assuming I'm not
able to get both shims in place, could I drive carefully with only one
or will that put too much stress on the pinion gear/bearing?

Thanks,
Ulf

In article >,
" > wrote:

> > You must often install and remove the shims several times to get things
> > right.
>
> I assumed that wasn't necessary since I'm not replacing the gears.

But you were replacing the bearings, the preload on new bearings
is different than the preload on used bearings not to mention any
production differences between the different bearings themselves.

> Anyway, I've removed the differential case from the car and the
> differential bearings look alright, the problem appears to be the thrust
> washers on the side gears. I can move both spider gears about 5mm / .2"
> left and right which I assume is too much play. This would be why
> there's play in the drive axles and the noise I've been hearing on left
> turns would be the left brake disc touching the holder of the caliper.
> Unfortunately, I don't have any new thrust washers, so I'm at a dead
> end. There doesn't appear to be any point of replacing the bearing
> either if it's good.

Makes sense, the F body rear axle isn't all that robust.

> The question remains whether I should try to put everything back
> together or just walk in with the diff to the mechanic. Assuming I'm not
> able to get both shims in place, could I drive carefully with only one
> or will that put too much stress on the pinion gear/bearing?

Couple of things...

Did the differential slip out easily or did you need to use a pry
bar to get it loose?

Did you mark the bearing caps WRT orientation, i.e., left and
right, top vs. bottom?

Did you mark the outer races WRT orientation?

Did you mark the side shims WRT which side they came from?

Did you measure the ring gear to pinion backlash before you
disassembled?

No, you can't drive at all with just one side shim in place.

aarcuda69062 skrev:
> In article >,
> " > wrote:
>
>>> You must often install and remove the shims several times to get things
>>> right.
>> I assumed that wasn't necessary since I'm not replacing the gears.
>
> But you were replacing the bearings, the preload on new bearings
> is different than the preload on used bearings not to mention any
> production differences between the different bearings themselves.

No, I skipped replacing the bearings, they looked fine.

>
>> Anyway, I've removed the differential case from the car and the
>> differential bearings look alright, the problem appears to be the thrust
>> washers on the side gears. I can move both spider gears about 5mm / .2"
>> left and right which I assume is too much play. This would be why
>> there's play in the drive axles and the noise I've been hearing on left
>> turns would be the left brake disc touching the holder of the caliper.
>> Unfortunately, I don't have any new thrust washers, so I'm at a dead
>> end. There doesn't appear to be any point of replacing the bearing
>> either if it's good.
>
> Makes sense, the F body rear axle isn't all that robust.
>
>> The question remains whether I should try to put everything back
>> together or just walk in with the diff to the mechanic. Assuming I'm not
>> able to get both shims in place, could I drive carefully with only one
>> or will that put too much stress on the pinion gear/bearing?
>
> Couple of things...
>
> Did the differential slip out easily or did you need to use a pry
> bar to get it loose?

Pry bar.

>
> Did you mark the bearing caps WRT orientation, i.e., left and
> right, top vs. bottom?

L & R on everything. Not T & B, is that important?

>
> Did you mark the outer races WRT orientation?

See above.

>
> Did you mark the side shims WRT which side they came from?

Yes, see above.

>
> Did you measure the ring gear to pinion backlash before you
> disassembled?

No, I don't have the tools.

>
> No, you can't drive at all with just one side shim in place.

Well, I got everything back together. No housing spreader needed, just a
rubber hammer. I'll let the pro's fix it, seems to be too much fiddling
to get it right and I'm no perfectionist. At least I gave it a shot... :-)

Thanks for the input everyone.

Ulf

In article >,
" > wrote:

> aarcuda69062 skrev:
> > In article >,
> > " > wrote:
> >
> >>> You must often install and remove the shims several times to get things
> >>> right.
> >> I assumed that wasn't necessary since I'm not replacing the gears.
> >
> > But you were replacing the bearings, the preload on new bearings
> > is different than the preload on used bearings not to mention any
> > production differences between the different bearings themselves.
>
> No, I skipped replacing the bearings, they looked fine.

I realize that. My comments were regarding proper service
procedure and avoiding pitfalls that usually result in early
failure.

<snip>

> > Did you mark the bearing caps WRT orientation, i.e., left and
> > right, top vs. bottom?
>
> L & R on everything. Not T & B, is that important?

Yes. You can not flip the bearing caps because they are machined
in place. if the bearing cap was originally installed like this
( [ ) and you re-installed it like this ( ] ), the bore will not
be centered and the outer bearing race will be unevenly stressed.
The same rules that apply to engine bearing caps apply to rear
axle bearing caps if you get my drift.
Hopefully in your case, the bearing caps will only fit in one
direction...

> >
> > Did you mark the outer races WRT orientation?
>
> See above.

good

> >
> > Did you mark the side shims WRT which side they came from?
>
> Yes, see above.

good

> >
> > Did you measure the ring gear to pinion backlash before you
> > disassembled?
>
> No, I don't have the tools.

Any time you R & R a ring gear/differential assembly, you want to
shoot for the same backlash as what it was before disassembly.

> >
> > No, you can't drive at all with just one side shim in place.
>
> Well, I got everything back together. No housing spreader needed, just a
> rubber hammer. I'll let the pro's fix it, seems to be too much fiddling
> to get it right and I'm no perfectionist. At least I gave it a shot... :-)

Please inform the pros that you were in there if there's any
question regarding whether the bearing caps were returned to
their correct positions.

aarcuda69062 > wrote in article
>...
> In article <01c79a12$794062a0$e194c3d8@race>,
> "*" > wrote:
>
> > > Given the original posters question, did you think he would have
> > > one to use?
> > >
> >
> > It's highly unlikely, but that doesn't change anything.
>
> It does if there are acceptable alternative methods.
>

Please outline the "alternative" method of applying the correct amount of
side-carrier bearing pre-load without moving the housing away from the cup,
then allowing it to create pressure against the cup when it is
relaxed.....providing the pre-load.


>
> > Also, if he doesn't have the tool, he might not be able to do the
> > job........correctly, that is.
>
> It can be done correctly if he uses the steel service shims that
> are available from GM and/or any number of aftermarket vendors.
>

Do these shims magically expand a certain amount for each thousandth of
thickness to provide correct bearing pre-load?


> > Just have to read ANY GM, RWD service manual...........The housings
STILL
> > have the holes for the spreader, and while some may ignore the correct
> > procedure, they are STILL used when assembling a rear axle correctly.
>
> That may be true regarding the original assemble at the factory,
> but necessarily true at the dealership level and certainly not
> true if one reads the instructions supplied with just about any
> aftermarket gear set/differential assembly.
> If one calls and queries Randy's Ring & Pinion, they will
> actually tell you -not- to use a case spreader on any GM axle
> including a 12 bolt.
>


They must have a lot of fun getting SOME of those 12-bolts apart without
using a spreader.


****REMINDER TO SELF.......Continue to set up your own rear ends using
correct, by-the-book, factory--and-manufacturer-prescribed methods - AND
specialized tools including housing spreaders - just as you have on the
dozens of 12-bolts and others that you have already set up for oval-track
and drag racing over the last 40 -plus years....Avoid Randy's Ring & Pinion
at all costs.

And, when you need a laugh, call the guys at Richmond Gear and tell them
about Randy's theories.

aarcuda69062 > wrote in article
>...
>
> That may be true regarding the original assemble at the factory,
> but necessarily true at the dealership level and certainly not
> true if one reads the instructions supplied with just about any
> aftermarket gear set/differential assembly.
> If one calls and queries Randy's Ring & Pinion, they will
> actually tell you -not- to use a case spreader on any GM axle
> including a 12 bolt.


Just checked Randy's website.....

It seems that they ONLY sell the DANA spreader - which doesn't fit other
"corporate" rear axles.....

How would you expect them to respond when customers ask why they don't have
a spreader for a 12-bolt?

"Aw, you need one, but we don't have it, so yiou'll have to go to one of
our competitors"

OR

"Naw....You don't need a spreader for anything but a DANA - and we HAVE
that one."

Of course, if you call back with a problem, the pat answer will likely be,
"Geez....we've never run into THAT before. You must have a mongrel or
something."


Thanks for the tipoff on how Randy's does business.......

In article <01c79d4b$934f3c20$ae91c3d8@race>,
"*" > wrote:

> And, when you need a laugh, call the guys at Richmond Gear and tell them
> about Randy's theories.

http://www.richmondgear.com/ringandpinion.pdf

Page 4.

Careful who you name drop.

In article <01c79d4b$934f3c20$ae91c3d8@race>,
"*" > wrote:

> ****REMINDER TO SELF.......Continue to set up your own rear ends using
> correct, by-the-book, factory--and-manufacturer-prescribed methods - AND
> specialized tools including housing spreaders - just as you have on the
> dozens of 12-bolts and others that you have already set up for oval-track

Hobby stocks, eh?

<yawn>

aarcuda69062 > wrote in article
>...
> In article <01c79d4b$934f3c20$ae91c3d8@race>,
> "*" > wrote:
>
> > And, when you need a laugh, call the guys at Richmond Gear and tell
them
> > about Randy's theories.
>
> http://www.richmondgear.com/ringandpinion.pdf
>
> Page 4.
>
> Careful who you name drop.
>

You know, it's kinda' strange how the guys in the shop and the guys in
marketing who maintain collateral material - such as charts, manuals and
websites - at larger companies never seem to communicate well with each
other.

Neil Nelson > wrote in article
>...
> In article <01c79d4b$934f3c20$ae91c3d8@race>,
> "*" > wrote:
>
> > ****REMINDER TO SELF.......Continue to set up your own rear ends using
> > correct, by-the-book, factory--and-manufacturer-prescribed methods -
AND
> > specialized tools including housing spreaders - just as you have on the
> > dozens of 12-bolts and others that you have already set up for
oval-track
>
> Hobby stocks, eh?
>
><yawn>
>

.....Yup.....and Street Stocks, and Sportsman, and Pro-Stocks.


Unlike some snobbish people, I don't look down on the people who can only
afford to race the lower classes. Instead, I work with them.

Their money is as good - if not better - than some of the upper class
racers.

I've NEVER been stiffed by a Street-Stocker.

I cannot say the same for Late Model/Pro-Stock racers - some of whom have
owed me money for years now.