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Rear End Noise


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Well something was bound to happen. My car has been mostly problem free since I acquired it in 2012. So today it was such a nice day I thought I'd take it for a spin after work. I was cruising about 35mph approaching a blind curve and all of a sudden around the curve traffic was completely stopped so I had to make a hard brake and wham! It sounded like something in the trunk slammed against the back wall. I didn't think too much about it as sometimes I forget to put everything away.  As soon as traffic started to move, I hear a rumble, grind, etc. Once I got the car out of traffic I checked the trunk to see what was rolling around... Nothing. I was able to limp back home. The rumble grind seems to intensify whenever I let off the throttle. I have not had a chance to get under the car yet. Hopefully it's something simple. Looking for things to check. Thanks in advance.

Edited by ingramlee

(1973 Fjord Blue 037) Vin 2588314- Build date February 6th, 1973- delivered to Hoffman Motors NYC February 8th.

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Here are my guesses; loose or damaged driveshaft, differential problems, rear suspension components out of alignment. A thorough inspection is necessary to pinpoint the exact cause.

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Add rear brake components to the list and/or cv joints. I would recommend starting by draining the diff oil into a clean pan and looking for metal flakes or chunks.

Edited by Son of Marty
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If everybody in the room is thinking the same thing, then someone is not thinking.

 

George S Patton 

Planning the Normandy Break out 1944

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Here's a little more info. I just jacked up the car and tried spinning the rear wheels by hand to see if anything seems out of whack. The driver side rear wheel rolled smoothly. The passenger side would not spin at all. Continued trying both wheels and finally I was able to get it to spin. Took it for a slow test drive.  Same thing, rumble, weird grind. Tried tightening the lug nuts on the PS rear wheel that wouldn't spin and it just doesn't sound good. I'll dig a little deeper tomorrow after work. Hopefully it's something with the braking system and not a wheel bearing.

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(1973 Fjord Blue 037) Vin 2588314- Build date February 6th, 1973- delivered to Hoffman Motors NYC February 8th.

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1 hour ago, jay02 said:

Here are my guesses; loose or damaged driveshaft, differential problems, rear suspension components out of alignment. A thorough inspection is necessary to pinpoint the exact cause.

 

Here's my guess-  a brake shoe's come loose.  Or that spreader's dropped down and is wedging the shoes apart.

Pretty unlikely it's a bearing, but hell, after 50 years, I needed some new marbles, and those are like bearings, right?

 

Dissassembly is neeesssesssarrrryysssss  beep.

 

t

also sounds like an AI

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"I learn best through painful, expensive experience, so I feel like I've gotten my money's worth." MattL

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Also check for the lining material parting company from the brake shoe itself, or chunks breaking off and wedging between shoe and drum.  Just encountered that on my own car and that of someone here on the FAQ.  And yes, I did a column about it, but you can diagnose and fix it yourself, as the problem will be obvious soon as you remove the brake drum.

 

Hope that's what it is as it's an easy fix...let us know whatcha find.

 

mike

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'69 Nevada sunroof-Wolfgang-bought new
'73 Sahara sunroof-Ludwig-since '78
'91 Brillantrot 318is sunroof-Georg Friederich 
Fiat Topolini (Benito & Luigi), Renault 4CVs (Anatole, Lucky Pierre, Brigette) & Kermit, the Bugeye Sprite

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Ok Folks.. I concede, I quit, I give up.  I've checked everything I can think of. It sounds like the old baseball card in the bicycle spokes. The sound is synched with the cars speed. Something is hitting something while spinning. Nothing askew inside the drums. I cannot hear it unless the car is driving⋯⋯meaning I've tried jacking up the rear of the car and spinning the rear wheels with the car running and in gear and I cannot hear it. I cannot hear it while under the car spinning the driveshaft by hand. Neither CSB or guibo are damaged or hitting anything while spinning driveshaft by hand. I've replaced the diff oil, no chunks or metal evident. I'm leaning towards the braking system simply because it happened right after a very hard brake episode. I'm also focused on the rear simply because I heard a thump in the back immediately after hard braking. Could a rear wheel bearing make that sound? I suppose.

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(1973 Fjord Blue 037) Vin 2588314- Build date February 6th, 1973- delivered to Hoffman Motors NYC February 8th.

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Did you try grabbing the half shafts and twisting, to test the CV joints?

 

There was another reported card in the bicycle spokes sound recently. That turned out to be a guibo that looked good until removed.

 

Guibos expand and flex when under force. I witnessed this while my 2002 was run on a dyno. Also learned the hard way when my guibo decided to remove itself and break the shift shaft and rear case on my 245 5 speed 😭.

 

I would carefully inspect the guibo with the brightest light you have and look for rubbing on the shift shaft directly above.

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I would also check the trans output flange they have been known to loosen up and spin on the splines.

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If everybody in the room is thinking the same thing, then someone is not thinking.

 

George S Patton 

Planning the Normandy Break out 1944

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5 hours ago, 2002iii said:

Did you try grabbing the half shafts and twisting, to test the CV joints?

 

There was another reported card in the bicycle spokes sound recently. That turned out to be a guibo that looked good until removed.

 

Guibos expand and flex when under force. I witnessed this while my 2002 was run on a dyno. Also learned the hard way when my guibo decided to remove itself and break the shift shaft and rear case on my 245 5 speed 😭.

 

I would carefully inspect the guibo with the brightest light you have and look for rubbing on the shift shaft directly above.

I was out of town all day today and didn't have time to do anything to the car. I will check the Guibo thoroughly in the coming days. A quick visual yesterday and it appeared in excellent condition. 

(1973 Fjord Blue 037) Vin 2588314- Build date February 6th, 1973- delivered to Hoffman Motors NYC February 8th.

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5 hours ago, Son of Marty said:

I would also check the trans output flange they have been known to loosen up and spin on the splines.

I will likely swap in my spare driveshaft to simply rule that out and will check the output flange at that time.

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(1973 Fjord Blue 037) Vin 2588314- Build date February 6th, 1973- delivered to Hoffman Motors NYC February 8th.

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10 hours ago, Son of Marty said:

I would also check the trans output flange they have been known to loosen up and spin on the splines.

This was a known problem on at least some '73s.  Apparently the flanges were poorly heat treated by the manufacturer, and the earlier coarse spline tranny output shafts wore, and then the flange worked loose on its shaft and wore the splines off.  That happened to my '73 not too long after I bought it in 1978 with 44k miles.  Had to replace the flange shortly after a clutch replacement--the dealer had a service bulletin on the loose flange, but failed to check it on my car.  My one and only visit to that dealer when he wouldn't make good on his carelessness.  

 

In early '74 the gearbox manufacturer went to a fine spline output shaft/flange, and that apparently solved the problem.

 

mike

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'69 Nevada sunroof-Wolfgang-bought new
'73 Sahara sunroof-Ludwig-since '78
'91 Brillantrot 318is sunroof-Georg Friederich 
Fiat Topolini (Benito & Luigi), Renault 4CVs (Anatole, Lucky Pierre, Brigette) & Kermit, the Bugeye Sprite

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15 hours ago, ingramlee said:

It sounds like the old baseball card in the bicycle spokes. The sound is synched with the cars speed. Something is hitting something while spinning. Nothing askew inside the drums. I cannot hear it unless the car is driving⋯⋯

From earlier experience a sound that matches discription was when handbrake cable was touching weights on backside of a wheel. Cable might have come out of a support during the incident. When spinning by hand you have the trailing arm in different position and it may not be touching. Just guessing here... But I don't think that wouldn't explain the jamming you discribred earlier. Did that go away though you didn't find anything?

Edited by Tommy
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Racing is Life - everything before and after is just waiting!

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11 hours ago, Tommy said:

From earlier experience a sound that matches discription was when handbrake cable was touching weights on backside of a wheel.

This will leave witness marks in short order, look for clean bright marks on the cable.

If everybody in the room is thinking the same thing, then someone is not thinking.

 

George S Patton 

Planning the Normandy Break out 1944

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