727 Loud shuddering bang/clunk noise under load going up hill *UPDATE*

[miller]

I also noticed when installing my new drive shaft, that the rear end has play in it--- or maybe that's not the best way to describe it.... more specifically, the yoke could be twisted back and forth a before it engaged the rear end.

Put the trans in neutral, and climb under the car, near the rear u-joint (at rear of driveshaft). Rotate the driveshaft, both directions, and look for any 'play', looseness in that u-joint. If there is, there's your 'bang', the u-joint is bad, and sooner or later, it will come apart! Should not be any play in the u-joint itself. There are several sizes, so you need to know which one is needed, if it is replaced.

Trans slipping? Could be just needs the bands adjusted...that's a snap for a trans shop, that knows what the hell their doing. How much time, since rebuild, if ever on it? If a lot of time...won't hurt to rebuild it.

 

[matthon]

Can anyone comment on points?

I'm no expert on points, I converted everything I have to electronic, but I recall a car where I had issues with setting the dwell, if I'm stating that correctly.
Sorry, I try to keep it simple as to not overlook the, well, simple stuff.

Also, having a rebuilt poly 2 barrel auto, I can state it's not quick or anything like that, but it gets up to speed well, cruises at speed nicely, and can get up a steep hill by my house w/o kicking the trans down. Of course, a little throttle and it kicks down nicely and will pull strong.
In my mind it drives and runs much nicer with electronic ignition, but I never ran it w/o.

I met a guy with a poly and he put a dual quad intake on it. Rebuilt engine, nice car. When asked if he noticed a performance difference, he hesitated, and said it eats more gas.

 

[Ron H]

There's some varying description with this bang noise and when this happens. I have a '63 PB with built up poly and put in a shift kit. It shifts harder than stock having set it at mid-level. Older 727's of our vintage don't kick down like the later ones do; a kickdown to 'passing' mode requires full throttle unless the trans is tricked up to do this. A heady pricy build up. The stock shift points are very low...in 3rd gear before 30mph closer to 25mph. This is why suggestion to climb the hill keeping it in 2nd gear to see if the bang happens to see if this may reveal a trans problem. From your other details, does sound like trans is slipping possibly banging sloppily into next gear going up the hill. If you have a sure grip rear this could be some clutch slipping. I'd not rely on any info the PO says as to what was done given the details you say about what things looked like. As posted, I'd take the car to a qualified trans shop for their check.

 

[Evan Frucht]

There's some varying description with this bang noise and when this happens. I have a '63 PB with built up poly and put in a shift kit. It shifts harder than stock having set it at mid-level. Older 727's of our vintage don't kick down like the later ones do; a kickdown to 'passing' mode requires full throttle unless the trans is tricked up to do this. A heady pricy build up. The stock shift points are very low...in 3rd gear before 30mph closer to 25mph. This is why suggestion to climb the hill keeping it in 2nd gear to see if the bang happens to see if this may reveal a trans problem. From your other details, does sound like trans is slipping possibly banging sloppily into next gear going up the hill. If you have a sure grip rear this could be some clutch slipping. I'd not rely on any info the PO says as to what was done given the details you say about what things looked like. As posted, I'd take the car to a qualified trans shop for their check.

Yes its looking like that is the plan, I agree that I need some expert help on this one. I'm starting to wonder if maybe me changing the fluid had something to do with it starting to act up terribly like this?

heard that new fluid can dissolve old sludge that gets into the valve body and can instantly ruin a transmission... don't know how common that is.

the old fluid didn't look that bad, it was definitely opaque and no longer clear but was still red in color, and not black or burnt or anything, or full of a bunch of stuff. There were some deposits of what I thought looked like clutch material but not a lot.
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it went from making a loud bang and seemingly shifting normal to major struggle to even move the car, very mushy delayed engagement, slipping all over the place. it was probably slipping a lot to begin with just not as noticeable. the thing has always struggled to move itself and I have had a hunch its the transmission, but had almost hoped it wasn't. again its been hard for me to diagnose properly for various reasons.

On the bright side if I need to rebuild it fully, I will feel better and more confident in the car knowing that the work was done right, and also I can decide what kind of shift kit or upgrades I want to do and tailor it to my preferences.

 

[Evan Frucht]

Put the trans in neutral, and climb under the car, near the rear u-joint (at rear of driveshaft). Rotate the driveshaft, both directions, and look for any 'play', looseness in that u-joint. If there is, there's your 'bang', the u-joint is bad, and sooner or later, it will come apart! Should not be any play in the u-joint itself. There are several sizes, so you need to know which one is needed, if it is replaced.

Trans slipping? Could be just needs the bands adjusted...that's a snap for a trans shop, that knows what the hell their doing. How much time, since rebuild, if ever on it? If a lot of time...won't hurt to rebuild it.

I had a drive shaft shop make me a brand new drive shaft with 2 new Spicer U-joints on each end and a slip joint with flange, to eliminate the old ball and trunnion. Its great and has no play whatsoever. I installed it 3 days ago after picking it up. I suspected my trunnion housing was worn out and those are not available new, so that's why I went that direction. I had hoped that would fix the bang/clunk I was feeling but now I have bigger fish to fry... my B/T was worn out anyway tho, so no harm done., probably good I got that out of the way

The play I was feeling was in the yoke that sticks out of the rear end, where the rear U-joint gets clamped into.

hopefully a good tranny shop may be able to adjust it and get it working without any major overhaul, but I'm ready for the worst case scenario at this point

 

[khryslerkid]

On the bright side if I need to rebuild it fully, I will feel better and more confident in the car knowing that the work was done right, and also I can decide what kind of shift kit or upgrades I want to do and tailor it to my preferences.

This was my thought when working on my '62. The car acually ran and drove. But I wanted to have the trans checked out so there wouldn't be any problems once on the road. I'm really glad I did. The teardown reviled a real mess inside. It's a wonder it even worked. It's worth the peace of mind to have it checked out.

www.1962to1965mopar.ornocar.com has good tips and descriptions on the proper removal and adjustment of the cables. Good luck and feel free to ask questions, as I know you will. Don't cut yourself short, you're doing a great job!

 

[Dipstick]

The play I was feeling was in the yoke that sticks out of the rear end, where the rear U-joint gets clamped into.

Is the play up/down/sideways or when rotating? If rotating, some play is normal but any other play is bad. Could be a simple thing like a loose pinion nut.

 

[Evan Frucht]

Is the play up/down/sideways or when rotating? If rotating, some play is normal but any other play is bad. Could be a simple thing like a loose pinion nut.

It's just rotational play so im thinking the rear end is possibly fine.

 

[JackpotJim]

I think it's time to go talk to someone at a transmission shop. Yes, the wrong fluid level in the AT can cause issues but you had the noise before you removed the AT pan and filter. Pretty obvious it's a driveline issue. Hate to see you losing sleep on this one. Let us know what you find.

 

[Evan Frucht]

Alright, so car has been at the shop since last Friday when I dropped her off.

Upon arrival, the shop owner and I took a drive. He immediately mentioned that it was slipping bad. I could feel it too. It took about 10 seconds for it to even engage into first and was very sluggish. We didn't go far before turning around... didn't make any "bang" but I think it would have with more pedal pressure. We were playing it safe. Decided it's time for a full rebuild.

Called him today to check progress. He had just started to tear it down, said there were no suprise's so far but it looked "old and decrepit" inside. He didn't think it had ever been fully rebuilt before, but said someone had done some work on it in the past because one of the bands had been replaced with flex band? (Not sure if I misheard him there...)

Anyway it's looking like I'll have running driving project in the next few days.

Thanks again for all the help everyone.

 

[Evan Frucht]

does sound like trans is slipping possibly banging sloppily into next gear going up the hill. If you have a sure grip rear this could be some clutch slipping.

Pretty sure what you describe as a sloppy shift is the "bang" I was hearing and feeling. After the slipping got quickly worse, it made the car completely undriveable and the need for a full rebuild became more and more clear...

I curious though specifically with what you say in regards to it being a sure grip rear end (which I think it is.) What is it about the sure grip, paired with a slipping clutch, that would cause such a loud and shuttering bang? And if that were to have done damage to anything, where might you suspect that damage to occur (in the rear end possibly?)

I'm probably just worrying in that respect but am interested to learn how you made that connection: sure grip rear end + slipping clutch = bang

 

[Evan Frucht]

The car is being towed back from trans shop. Will test drive when it gets home.

He gave me a box of the old parts I will take pictures of it. The front clutch disks were completely stripped of the clutch material and they are just bare metal. Lots of broken **** inside. Will post some pics when I get home. It's a wonder the car even moved to begin with...

 

[Wallus57]

When going up hill my 64 Fury is making a loud clunk or bang which sort of shakes and shudders the whole car as it happens. This happens when I accelerate up the semi steep hill that is my street. And it only happens for a moment and then goes away.

When car is revved up in neutral or park it sounds very smooth with no vibration or sounds whatsoever.

I thought it may have been the old ball and trunnion drive shaft which was clearly worn out. I just had a brand new custom drive shaft with a slip joint and double U-joints made and installed it. Paid 400 for it. All brand new and balanced. It might have reduced some vibation's a little, but the high load bang/clunk is still there.

The car has its original 318 poly/push button 727 combo

PO told me had the engine, trans, and rear end rebuilt but had no paperwork becase it was aparrently lost in a storage unit. I sort of believe him given how well the engine runs, but something isn't right in the transmission, or possibly rear end--but that seems less likely than trans. It isn't making any grinding or whiny noises.

The ATF fluid level may be a little on the low side but it was shifting through all the gears properly it seemed.

Could low fluid level cause a loud shuddering bang?

Any ideas what component in the transmission may be causing this?

Does it make a squawking sound at that time? If so it could be that the trans is kicking down to 2nd gear which will put a high torque load on the rear roller clutch. If that clutch is worn it can slip then grab suddenly and cause a squawking sound and a bang when it grabs. It could also be the intermediate band coming on with a thump.

 

[493 Mike]

Does it make a squawking sound at that time? If so it could be that the trans is kicking down to 2nd gear which will put a high torque load on the rear roller clutch. If that clutch is worn it can slip then grab suddenly and cause a squawking sound and a bang when it grabs. It could also be the intermediate band coming on with a thump.

The over running clutch is only used in 1st gear.
Mike

 

[Loulang]

So what was wrong with it?

 

[oldkimmer]

He was last on here April 05/2023. Calling @Evan Frucht