help before I burn her
Thread Starter
Advanced
Joined: Jan 2011
Posts: 57
Likes: 0
From: alabama
help before I burn her
Let me start by stating I'm NO mechanic.
and i know diagnosing issues over the internet is a all but impossible but i'm hoping for some advice.
I have a local mechanic. but right now i cant afford the $90 an hour rate
1978 l-48 silver anniversary with a intermittent grinding\rubbing noise from driver's side rear. it almost feels like something catching? only occurs after 25-30 minutes of driving. My first thought was the brakes were not releasing correctly (ALL parking brake hardware removed by previous owner)
checked caliper and it appeared fine. rotor had seen better days and was very slightly warped. so i replaced both rear rotors and pads.
drove great till about the 35 minute mark then the sound reappeared.
so now im stuck. i dont know what else to check. i thought rear bearings but the sound isnt a squeal and i didn't think they would take 30 miles of driving to start showing signs of failure.
could it be the differential maybe. but it only comes from drivers side.
any help\advice or even just encouragement would help.
sorry so long winded
Thnx in advance
J
th
and i know diagnosing issues over the internet is a all but impossible but i'm hoping for some advice.
I have a local mechanic. but right now i cant afford the $90 an hour rate
1978 l-48 silver anniversary with a intermittent grinding\rubbing noise from driver's side rear. it almost feels like something catching? only occurs after 25-30 minutes of driving. My first thought was the brakes were not releasing correctly (ALL parking brake hardware removed by previous owner)
checked caliper and it appeared fine. rotor had seen better days and was very slightly warped. so i replaced both rear rotors and pads.
drove great till about the 35 minute mark then the sound reappeared.
so now im stuck. i dont know what else to check. i thought rear bearings but the sound isnt a squeal and i didn't think they would take 30 miles of driving to start showing signs of failure.
could it be the differential maybe. but it only comes from drivers side.
any help\advice or even just encouragement would help.
sorry so long winded
Thnx in advance
J
th
Drifting
Joined: Jul 2004
Posts: 1,695
Likes: 65
From: Kissimmee fl
Finalist 2021 C3 of the Year - Modified
2017 C3 of Year Finalist
Cruise-In VIII Veteran
St. Jude Donor '07
My guess is a bad universal joint. Get the rear up in the air then support the trailing arms. Spin the wheels and feel for the tight spots.
Race Director
Joined: May 2006
Posts: 16,528
Likes: 53
From: Dayton, Ohio
Sounds like the classic posi clutch chatter problem.Mainly when your pulling away from a stop sign ?
Eyeball your u-joints for signs of rust coming from the 4 cups,no rust,don't fret just change your fluid w additive and drive some and see if it goes away.
Drifting
Joined: Jun 2010
Posts: 1,781
Likes: 15
From: Oxford Ohio
Roll down your windows and drive slowly in an alley or someplace with walls on your sides. Listen for the noise. Usually a u joint will have a double squeek. Squeek squeek for lack of a better description. A wheel bearing will normally have a rythmic squeek. The U-joint will move two directions with every turn of the wheel where the bad wheel bearing will sound like the noise is coming from one spot of the wheel.
Unless the wheel bearing is in very bad shape from being bad for a longer lenth of time. Then it will be a constant squeek.
Unless the wheel bearing is in very bad shape from being bad for a longer lenth of time. Then it will be a constant squeek.
Intermediate
Joined: Jul 2010
Posts: 37
Likes: 0
From: Fowlerville Mi.
Sounds very much likewhat I had on my 77, a grabbing sort of feel on the driverside wheel. Only after driving a while, and only at a stop then takeoff. Felt like the tire was loose, or brake caliper was grabbing. Long story short, pulled the rear end, replaced a worn yoke on driverside, and new rear end oil and posi addative, Have driven a year on it now and have never felt or heard it again.
Melting Slicks
Joined: Oct 2002
Posts: 2,317
Likes: 111
From: St Louis MO
I had a noise like that many years ago and it was the left wheel bearing - you will want to attend to it before it becomes catastrophic.
If the noise occurs when turning (especially at lower speeds) and feels like a pop and catch, I'd expect posi clutch problems as noted above.
If the noise occurs when turning (especially at lower speeds) and feels like a pop and catch, I'd expect posi clutch problems as noted above.
Thread Starter
Advanced
Joined: Jan 2011
Posts: 57
Likes: 0
From: alabama
thnx guys for responding
If I were to change the fluid in the differential what fluids should i use. what viscosity and its a limited slip does that require a special additive?
can these be purchased from a parts store or should i order them online
If I were to change the fluid in the differential what fluids should i use. what viscosity and its a limited slip does that require a special additive?
can these be purchased from a parts store or should i order them online
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Thread Starter
Advanced
Joined: Jan 2011
Posts: 57
Likes: 0
From: alabama
$$$
alright
if i was gonna get a shop to do a differential service anyone out there got a ruff idea on a average cost.
1. just a service (no parts)
or
2. full rebuild
I know prices can very significantly i just need something to go by.
shops tend to see me coming! LOL
Thnx in advance
J
if i was gonna get a shop to do a differential service anyone out there got a ruff idea on a average cost.
1. just a service (no parts)
or
2. full rebuild
I know prices can very significantly i just need something to go by.
shops tend to see me coming! LOL
Thnx in advance
J
Burning Brakes
Joined: Oct 2006
Posts: 1,006
Likes: 28
From: Lutz Florida
When you replaced the rear rotors did you have to drill out the rivets? Check to make sure a rivet or piece of rivet left in the hub couldn't be the culprit. With the parking brake hardware removed therre would be less for the rivet to cach on and grind against the inside of the hub but you never know.
Some times its the little things that get ya.
Some times its the little things that get ya.
Racer
Joined: Nov 2009
Posts: 489
Likes: 1
From: Suffolk Virginia
My posi clutches went out last year. I was quoted by a corvette shop ($100/hr) around $1100 for parts & labor, plus $2oo for new stob axles if needed. I pulled it myself and had a GM mechanic friend replace the clutches, he charged $200.
If yor car starts acting up after 20 minutes and chatters when you turn, that's probably you problem.
There's no drain plug on the rear end, you have to suck out the fluid.
If yor car starts acting up after 20 minutes and chatters when you turn, that's probably you problem.
There's no drain plug on the rear end, you have to suck out the fluid.
Le Mans Master
Joined: Mar 2008
Posts: 5,948
Likes: 72
From: Oxford MA-----You just lost the game!!!!
My posi clutches went out last year. I was quoted by a corvette shop ($100/hr) around $1100 for parts & labor, plus $2oo for new stob axles if needed. I pulled it myself and had a GM mechanic friend replace the clutches, he charged $200.
If yor car starts acting up after 20 minutes and chatters when you turn, that's probably you problem.
There's no drain plug on the rear end, you have to suck out the fluid.
If yor car starts acting up after 20 minutes and chatters when you turn, that's probably you problem.
There's no drain plug on the rear end, you have to suck out the fluid.
If you take the car for a drive, it'll warm up the diff fluid and make it easier to suck out, but don't let it get too hot, or you'll burn your lips on the diff cover.......
Scott
Racer
Joined: Mar 2002
Posts: 406
Likes: 1
From: Maroochydore QLD
I know you said the park brakes were removed but IF the cables are still in the car they can easily rub on the inside of the tires, makes a terrible noise, mine actually rubbed on the wheel weights and make a loud tap tap sound as the wheel turned. Look underneath for the wire wound cable from the hub to the frame clamp and make sure they have at least half inch clearence from the tire.
Worth a look, Dennis.
Worth a look, Dennis.
Thread Starter
Advanced
Joined: Jan 2011
Posts: 57
Likes: 0
From: alabama
haven't given up yet!
well i appreciate all the advice.
nothing rubbing and wheels seem to have very little play
I guess my next plan of action will be to change the fluids in the differential. so here's my next question what's the right fluid and additive to use.
exp- would it be better to use stock from gm or some kinda performance fluids such as lucas or royal purple.
and can these be bought at a parts store? locally i have autozone,advance,or orielly's
what are they called?
thnx
J
nothing rubbing and wheels seem to have very little play
I guess my next plan of action will be to change the fluids in the differential. so here's my next question what's the right fluid and additive to use.
exp- would it be better to use stock from gm or some kinda performance fluids such as lucas or royal purple.
and can these be bought at a parts store? locally i have autozone,advance,or orielly's
what are they called?
thnx
J
Le Mans Master
Joined: Aug 2006
Posts: 7,419
Likes: 1,555
From: mount holly NC
2025 c3 ('74-'82) of the Year Finalist - Unmodified
2019 C3 of Year Finalist (appearance mods)
Trying to remove the cover is hard!
You can get a cheep siphon pump at most auto parts stores.
You can get a cheep siphon pump at most auto parts stores.
Burning Brakes
Joined: Jun 2008
Posts: 1,086
Likes: 1
From: Michigan
I agree with trying this first as it seems to fix most issues that are similar to that which you described. Be sure to use the GM additive and not a generic type. 4 oz bottle is usually enough. If this doesn't work go the next step.