Rear end howl
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Cozi
Rear end howl
When I back off the gas and the car is "floating" between accelerating and decelerating I am getting a pretty good howl out of the rear end. It's not low on oil. Backlash? Can it be adjusted out?
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manoa matt
- Posts: 3442
- Joined: Thu Oct 26, 2006 4:28 pm
- Your car is a: 1978 Fiat 124 Spider 1800
- Location: Honolulu, Hawaii
Re: Rear end howl
Uh oh, get ready to replace that ring and pinion, or find a spare rear diff.
Same thing happend to me a few weeks ago. All the sudden one day it started to howel on deceleration and engine braking (reverse loads). The diff lasted about 2-3 weeks like that. Then one day comming off a stop sign BANG! and the pinion teeth shreaded. The pinion yoke nut did not come loose, and the case was filled with oil, so I'm not sure what was the exact cause, but I have several possible causes, like most disasters it was probably a combination of all the factors added up.
About 2 years ago I replaced the pinion shaft oil seal without renewing the crush sleve. Drove fine for 2 years with no issues and the nut did not come undone at the final blowout.
About 6 months ago I changed the diff oil from Valvoline to Lucas.
I frequently park on inclined surfaces, keep in mind the lack luster performance of the parking brake. I think the trans and rear diff gears are what was holding the car in place most of the time.
I found it odd that the noise started all the sudden one day as I left the parking garage at work. The noise started as I was going down a ramp, but no noises on the way to work, and no hot rodding to tear it up in the first place.
The ring gear moves side to side via shims, while the pinion moves forward and rearward via a crush sleeve.
I'd find a reptutable shop that knows how to setup rearends and have them take a look at it before it gets worse or lets go. The ring and pinion, shims and crush sleve are available through either Classicricambi.com or Autoricambi.com
The blessing in disguise for me was I already had a spare rear diff lying around, and it had a better ratio.
Same thing happend to me a few weeks ago. All the sudden one day it started to howel on deceleration and engine braking (reverse loads). The diff lasted about 2-3 weeks like that. Then one day comming off a stop sign BANG! and the pinion teeth shreaded. The pinion yoke nut did not come loose, and the case was filled with oil, so I'm not sure what was the exact cause, but I have several possible causes, like most disasters it was probably a combination of all the factors added up.
About 2 years ago I replaced the pinion shaft oil seal without renewing the crush sleve. Drove fine for 2 years with no issues and the nut did not come undone at the final blowout.
About 6 months ago I changed the diff oil from Valvoline to Lucas.
I frequently park on inclined surfaces, keep in mind the lack luster performance of the parking brake. I think the trans and rear diff gears are what was holding the car in place most of the time.
I found it odd that the noise started all the sudden one day as I left the parking garage at work. The noise started as I was going down a ramp, but no noises on the way to work, and no hot rodding to tear it up in the first place.
The ring gear moves side to side via shims, while the pinion moves forward and rearward via a crush sleeve.
I'd find a reptutable shop that knows how to setup rearends and have them take a look at it before it gets worse or lets go. The ring and pinion, shims and crush sleve are available through either Classicricambi.com or Autoricambi.com
The blessing in disguise for me was I already had a spare rear diff lying around, and it had a better ratio.
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baltobernie
- Patron 2020
- Posts: 3466
- Joined: Sun Nov 25, 2007 6:00 pm
- Your car is a: 1973 Spider [sold]
- Location: Baltimore, MD
Re: Rear end howl
Good points, Matt.
You didn't describe your car or where you're located, Cozi, but the entire rear axle can be replaced by an amateur with hand tools. This is often a cost-effective solution if you're near a boneyard, as the bodies rust away far quicker than diffs wear out. (Often you must also swap the panhard bar and trailing arms, too). Do a Search on this forum about identifying the different axle ratios used throughout the years, and the possible benefits of changing ratios.
You didn't describe your car or where you're located, Cozi, but the entire rear axle can be replaced by an amateur with hand tools. This is often a cost-effective solution if you're near a boneyard, as the bodies rust away far quicker than diffs wear out. (Often you must also swap the panhard bar and trailing arms, too). Do a Search on this forum about identifying the different axle ratios used throughout the years, and the possible benefits of changing ratios.
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Cozi
Re: Rear end howl
It's an '81 Spider. The PO installed a rear end out of I don't know what but the ratio has to be 4 something. The speedometer is at least ten percent off on the high side. I'm in fifth gear five seconds after I'm out of the driveway...... So like you Matt, this is my opportunity to "relax" things a bit. Just gotta find the pieces.