howl/whine after 10 miles

68Firebird
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howl/whine after 10 miles

Post by 68Firebird »

Hello and kudos on the cool site!!

I was refered here by 67Drake over on the PY forums.

My issue is after my firebird is run for about 10 miles or so I get a mild howl/whine that starts
at 45 MPH. Car is smooth with no other vibrations. So far I have replaced the outer axle
bearings, U-joints and did a fluid change in rear. I am running the original XE rear which is
a 3:08 std differential(non posi). Car has 73,100 miles and noise started late fall last year.

While I had the cover open for the fluid change and drv shaft off I did some investigating here is what I found.
-It takes more force to spin comp flange reverse than it does forward(can do it with one hand, but takes double the torque)
-no slop felt on comp flange up/down or in and out.
-before I removed axles I noticed if i rotated the passenger axle I could here the spider gears rotating. The spider
gears have visible wear. looks as the tips of gear are worn down as compared to ends of the spider gear. And on
some of the you can feel a ridge at the end of the spider gear. I can easily rotate the smaller gear and does not
feel as mesh it tight between the four gears. I don't believe these are my issue as I thought they would not be
rotating if I am driving straight????
-I chked backlash with a dial gauge as it showed in my svc manual. reading off the heel of the ring in direction of
rotation I am seeing .021??? I am concerned with this measurement. Carrier seemed tight and gears looked good
to naked eye. Tell me if I am goingin the right direction
-Sorry for being log winded. Gerry C
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monzaz
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Re: howl/whine after 10 miles

Post by monzaz »

LONG WINDED...NOT- Very good thorough info for us to resolve your problem.

OK first thing double check that back lash reading...IF it is still .021 THAT IS a huge problem and the reason the gear spins easy one way and not the other.

YOu need to post a few shots of the faces of the coast and drive side of the gears for us in varying distances to up close.

Spiders sound like they could use a replacement before they totally let loose and take out parts you do not want destroyed.

PLease remove the carrier caps after you take the recheck backlash reading. Once you do have the axles out and the caps off pull the carrier out toward you...if the carrier comes out easy or FALLs out check your carrier bearings as they are probably worn out...Check the races for damage... pitting galling etc.

Jim
J D Race
68Firebird
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Re: howl/whine after 10 miles

Post by 68Firebird »

Thanks for the tips!!!!!!!!
I picked up some marking compound and will take a few pics of pattern and double chk backlash.
I want to do this right the first time.
If the gears chkout ok can I just replace/upgrade to a posi carrier?
Part of me would like to upgrade to a 3:36/Posi setup. The cam I am running only came from
factory with 3:55 and higher ratio. motor is stout and felt a 3:36 would be a good compromise as
I enjoy cruising on highway as well.

Thanks

Gerry C
68Firebird
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Re: howl/whine after 10 miles

Post by 68Firebird »

Jim,

Here are a few pics to show patern I am getting. The backlask chked twice 180 apart is .020
Please don't laugh at jig I made to hold dial gauge.
Didn't want to drop carrier until you saw pattern on ring gear.
IMG-20120222-00002.jpg
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68Firebird
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Re: howl/whine after 10 miles

Post by 68Firebird »

A few more
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68Firebird
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Re: howl/whine after 10 miles

Post by 68Firebird »

Jim I took your advice and dropped the carrier. Yeah just like you said it fell right
out. And yes you called it the bearing races on the carrier bearings were heavily
pitted on upper half of race on both sides. The pinion was a bitch to get out but
the races on them were good. I enclosed some pics of the ring and pinion and the
pitted bearing race. I will call you to discuss options for replacement and pricing.
leaning toward reusing R&P, but need to weigh out options.

Thanks

Gerry C
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68Firebird
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Re: howl/whine after 10 miles

Post by 68Firebird »

more pics
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photo5.JPG
photo4.JPG
67drake
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Re: howl/whine after 10 miles

Post by 67drake »

Wow,after looking at that bearing race I can why it was making noise!
Image
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monzaz
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Re: howl/whine after 10 miles

Post by monzaz »

Gears look to be in very good condition. The carrier bearings and races need replacement and if the whole rear is original a rebuild kit would be the smartest move here. Auburn sells a Posi unit that will hold the 2.93 3.08 and 3.23.

3.08 gears are very good for all around driving and you can even hit the track on the special Pontiac days. :)

Jim
J D Race
68Firebird
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Re: howl/whine after 10 miles

Post by 68Firebird »

Jim it was great talking with you, and I appreciate you taking the
time to get back to me. I can see why people praise your customer
service!!!! Payment has been sent and I can't wait to get the new
posi in and setup.

ThanksAgain,

Gerry C
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monzaz
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Re: howl/whine after 10 miles

Post by monzaz »

Glad to help... :) Jim
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68Firebird
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Re: howl/whine after 10 miles

Post by 68Firebird »

Jim,
Thanks again for the call back on Saturday. You were right the splash shield was rubbing a hair
to much and causing the bind. Did as you said to get clearance and pinion is constant resistance.(no bind)
Well I got the Posi in tonight, took 14 times to get right combo for shims. What do you think??
driver side shim .263, passenger side shim .224, backlash right at .010 this was after caps were torq'd
to 70 ft lbs and carrier was rotated 10 revs both directions to seat bearings. Had to lightly tap in passenger
shim with small ball peen hammer and using wood dowel to drv shim. took pattern pipcs after rotating 15 times
in both directions.
Should I should for closer to .008 with these used gears??
thanks again

Gerry
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68Firebird
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Re: howl/whine after 10 miles

Post by 68Firebird »

One more
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monzaz
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Re: howl/whine after 10 miles

Post by monzaz »

Absolutely Beautiful. That is how a GOOD used gear set should look see how it swipes the complete gear face all the way across. It is so complete you really can not tell the pattern.

How does it feel now spinning the ring gear with out the drive shaft connected? Should be smooth both ways and ZERO noise.

WELL done.

BAcklash. If you want it nice an quiet leave it at .010 If your looking for more strength on hard launches etc tighten it up. I say you look very good and would leave it. How has the pinion preload come out? NO in out and the should be smooth snug turn If you have the inch pound wrench 10-15 used bearing New bearings 20-24 inch pound.

Jim
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68Firebird
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Re: howl/whine after 10 miles

Post by 68Firebird »

Jim,

Thanks I feel much better now! The torque to spin the pinion is the same now
both forward and reverse. And the only noise is when you change direction, you
hear a slight tink when going from forward to reverse. This is quieter then before
as now the lash is down to .010. Guess all I need to do is double chk everything
and reinstall axles, drv shaft and fill her up!!!!!!!

Since I am running used gears how would you break it in. I plan to take it easy on
her for the first 20 or so miles.

Thanks Again

Gerry C
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