Customs Grinding Sound part throttle

There was a post a while ago about a suspected bad wheel bearing (I believe that was what it was initially thought to be) but it turned out to be a parking brake cable contacting the driveshaft.

 

He already told us nothing is rubbing anywhere. (I’m assuming he looked) So it has to be internal.

 

I can’t imagine it being the tranny internals,,,,,,having a terrible grinding sound at upper speed,,,,and not anything at all much lower .
If it’s a wheel bearing,,,,you can feel that and isolate it .
If it’s an axle bearing,,,,,,should be the same,,,,,you should feel it and figure if it’s right or left .
Differential bearings, or gears,,,,,,same same .

That car is sitting very low,,,,,and at speed,,,,it will squat some more .
Might even be dragging something on the ground at 70 mph .

Tommy

 

The only way I found that the dust cover was where the grinding was coming from was to remove it. Once out I could see that the paint had been worn off where it was making contact. Not visible any other way.

 

At 70 things aren’t exactly under a light load. The rear end is pushing the car forward. The drive train is spinning 2500 or more rpm. The stresses are huge is what I’m trying to say. Check for stuff flexing, twisting binding or just in general moving. Lay your eyes on it also don’t just trust your friends who you have to pay for their experiments.

 

Can't wait to hear what this ends up being. You too I bet.

 

I'm going to suggest motor and transmission mounts. If you get the noise from light acceleration, can you get the noise without the car moving down the road by light brake torqueing it?

You mentioned that you raised up the air bags "a little" and it change things, maybe for a test, you should raise up the air bags a lot, to see if the noise goes away completely. That would at least give you a direction to pursue, and could eliminate a lot of stuff.

With the back end that low, any noise under the car will be trapped under the car and make you think its coming from the rear. It could be something as easy as transmission cooler lines rattling against something. If you keep telling your buddy that works on cars for a living, that the noise is coming from the rear, that will be where he most likely looks and might not see something towards the front. Have you had him drive the car and hear the noise?

Also, unless your buddy has a drive on hoist, or a two post that picks the car up by the axles, a regular hoist most places have lift the body up off the suspension, which isn't going to help you, most likely. This would especially be true if raising up the air bags a lot makes the noise go away.

 

Buy or rent on of these . It’s a chassis ear .

this thing saved me so much time when I worked at Jaguar looking for strange noises .

those cars could have a rear strut making a strange noise and me and every other tech in the shop would swear it’s coming from the glove box !!!
Sound travels and transfers and can do crazy things .

the alligator clips have mics in them you can hook up all 6 at the same time on different parts and switch between channels while driving .

it might even be part of a loan a tool program .


Stop throwing money at this issue and diagnose it.

Noise that happen only when driving are a pain in the ass to find.

good luck! Keep us posted .

 

Maybe try taking a video and putting it on YouTube or somewhere we can all listen to it?

 

man you have no idea. been getting this thing ready for awhile and its my last obstacle. everything is great but this si killing me.

 

ive tried raising it all the way but the change isnt much. then when you go too far it rides like shit because the bags are maxed out. we have had it on two and four posts and still the same. i guess im still just thinking its rear end due to the noise location. ive had a friend put his hand on the floor board while tis doing it and its still going back to rear end. i was thinking maybe plantary bearing in the trans after everything was done since its literally all new gears and bearings in the rear. but that doesnt mean anything either. i mean when i say a grinding noise its a grinding noise.....but now only after 65mph. very little with low speeds now after the u joints but tis still there at higher speeds.

 

ill try that. need to go get a battery, whole other issue after the fuel injection install, but i will do that this week.

 

man i saw this on a youtube channel. pretty damn neat. at this point im going to try that.

 

yeah i was hoping it was something like that. ive starred under there for so long on my back looking for anything hitting. i hope it is something like that

 

Maybe check the starter gear for clearance?

 

I ain't NEVER seen no sh*t like that before. And for $109 it isn't really stupid spendy. Did you ever use this rig for chasing down wind noises?

I ain't NEVER seen no sh*t like that before. And for $109 it isn't really stupid spendy. Did you ever use this rig for chasing down wind noises?

 

When you suspect rear diff and say the noise is grinding. Is it gear whine? At certain throttle positions, the rear may whine some. In the old rods with limited sounds deadening compared to DD, and driver sitting very near the rear axle due to short wheelbase, it is normal to hear some whine.

 

Now, back to the problem at hand.

Electric fuel pump? Mounted in or out of the tank? If outside, is it bolted directly to a metal bracket or mounted in some rubber bushings?

How is the rear suspension mounted? Rubber bushings, plastic bushings, Heim joints for rod ends?

 

internal fuel pump with the sniper kit. the noise was before i moved it into the tank.

rear suspension is 4 link. front end stock with basic upgrades for bags. its something in the rear. really feels like a rotation issue internal related to the speed of rotation. however, prior it was related to the amount of pedal pressure. very light pressure gave a 'grind'.....at higher speeds no matter the pedal pressure it was a horrible grind at anythign over 68 or so.

 

its like a metal on metal grinding sound....it could be considered a whine maybe at low speeds under light acceleration but after 65 its with no acceleration or with acceleration its a grinding metal on metal sound

 

i understand. im having a hard time laying my eyes on it....ive been under there more times than ive been in it. just seems very internal.

 

A 41 Plymouth coupe has a 117" wheel base. That is nota very short wheel base car.
1938 was the last year for the short wheel base Plymouth coupes at 112" WB.
A 41 Plymouth coupe actually has a longer wheel base then a 48 Plymouth business coupe by 1"

 

A Mopar 8 1/4 wheel bearing sets inside the axle housing and the roller bearing runs actually on the axle like many GM cars do. Are the axle shafts good? A small pit on the axle itself where the bearing runs will give you noise.

 

When I had a differential noise, I took the guy at the diff repair shop for a little ride. He knew immediately what caused the noise I described.

 

If you think it is an axle bearing take the car out and do a swerve test. Find a piece of road where where it will make the noise and there is enough room to gently swerve the car back and forth. The body roll will load the opposite side of the car from the direction you are swerving. One direction will make the noise increase and the opposite direction should decrease the noise. (Just make sure that car sitting way up ahead on the shoulder isn't a cop. It was dark.)

 

I would think that if the trans or differential had a horrible metal to metal grinding noise, it would destroy something

Ricky.

 

I had an O/T bmw years ago that would make an intermittent grinding noise .

then it turned into an intermittent banging noise.

the cross shaft that held the spider gears in place came loose and was rubbing on the housing and after a while came a bit more loose and would hit the housing .


It was a beater so while it was only a grind here and there I did not care , when it became a bang , I cared !

slid it back in n place and welded it solid. Like I said it was a beater and only needed to last so long .

 

they looked good when we did the bearings.

 

I've seen the center of a flex plate torn out; apparently it made all kinds of strange noises for the long time it took to fully fail and the car not move. It even ran with the center unknowingly torn out. Had lots of grinding but still maintained drive until it had eventually machined itself such that it wouldn't catch to provide drive. A bit like a slipping chain. Hard to find as it was between the crank and converter, so hard to see.

Probably not your problem but I'm sure worth a mention.

Chris