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cerick305

1947 Plymouth P15 gear grinding

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I am a new owner of a 1947 Plymouth P15 businessman's Coupe.  I have done minor repairs on it but been having an issue with grinding going into 1st, 2nd, sometimes 3rd, and reverse.

First off, I did adjust the clutch turnbuckle to get 1" of free play.  I also adjusted the screw that is connected to the qassembly and goes into the clutch to engage.

I had it set so I would barely press the clutch and it would disengage.  I then push the pedal all the way to the floor and still get grinding.  If the  transmission strats to disengage when I barely press the clutch, surely it should be completely engaged as I press it to the floor.  But still get grinding.

 

Second, I adjusted the screw outside of the clutch so that the clutch would need to be almost pressed to the floor before it would didengage the trans.  And still get grinding. 

 

I also changed the transmission oil to the recommended sae80 gear grease.  Not sure what was in there before, but regardless I had the grinding before the change and after.

 

I really love this vehicle and I drive it as often as I can, enven with the grinding.  I did notice If I slowwwwwwwwly put it into a gear with clutch pressed for several seconds, SOMETIMES it will not grind. 

 

I adjusted the link and the clutch screw millions of times and got nowhere.  Anyone have any suggestions?

 

Thanks,

Chad!

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First and reverse don't have synchronizers so they will grind unless everything comes to a full stop before you select them.

 

Second and third should be free of grinding however. If your clutch is fully disengaging then perhaps your transmission’s synchronizers are worn out. Any other possible transmission issues (popping out of second on deceleration or long down grade, odd noises, etc.)?

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When you mention screw outside of the clutch what screw are you talking about? Is  it the one attached to the clutch fork in the picture below? If so that is the free play adjustment.

 

What turn buckle are you talking about? The one shown below the clutch pedal in this picture? If so that is not the free play adjustment. That is the over center spring adjustment.

 

Do you have a service manual for your car? If not it is one of the best tools you can buy.

 

Clutchlinkage.jpg

 

 

overcenter_spring.jpg

 

cl19.jpg

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TodFitch, No poping out of gear or any strange noises other than the initial griding noise getting into gear.  I have had several insidents where I was not able to get into reverse and needed pushed out of a parking spot. 

 

Don, yes to both of your questions.  I adjusted both the free play and over center spring adjustment.  I now have 1" of free play in clutch.  Afer trying all combinations of adjustments, I did not find any that would stop the grinding noise.  I do have a service manual, but still having problems with getting this to work properly.

 

 

 

Thanks,

 

Chad

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Adjusting the over center turn buckle has nothing to do with free play. In fact the free play adjustment rod should be disconnected and removed when the over center turn buckle is adjusted. The function of the over center spring is to apply spring pressure to the pedal in both the full up and full down position. Once the over center adjustment is complete then the free play rod should be adjusted. In your initial posting it did not sound like it was done correctly. It sure sounds like your clutch is not fully disengaging. If you are comfortable this adjustment has been done correctly than I will shut up.

 

Whey you say you could not get the car into reverse and had to be pushed out of parking spots is that because the gears were grinding? Did you try placing the transmission in reverse prior to starting the engine? And if you do this does the starter motor spin the engine OK?

 

When you shift into first and or reverse from a dead standstill does the car lurch forward or backward? From a dead stand still have you tried to first slip the car into second gear then quickly into first or reverse? By doing this the second gear synchronizers should mesh without grinding and stop the transmission counter shaft from spinning allowing a smooth shift into first or reverse.

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Your pictures are what made me ask the question, I remember him showing everyone on the forum his interior that he installed himself.  He bought the seat covers and matching pleated and rolled material and covered his on door panels and kick panel.  I remember that he also did his own head liner installation, he was quite proud of his accomplishments as well he should of been.  I would never attempt to install a headliner as it would require more patience than I possess.

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Don,

The only reason I believe clutch is fully engaged is because the clutch would become disenganged after pressing the petal down more than a few inches.  I figured it would surley be completely disenganged as I pressed it further down. 

Yesterday I noticed if I apply the clutch a 3-5 seconds and then shift into 2 or 3rd, I do not get any grinding.  When I'm stopped and put car in 2nd and then into first, again no grinding.  I am wondering if it's my sync takes longer to stop spinning when I apply the clutch..?? 

 

Also, I can post some pictures of my Special Deluxe coupe a little later.  The interior is the original fabric cloth seats in a greyish color.

 

Thanks again for your help..

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I recently changed the lube in the trans with SAE80 gear grease (because of the grinding).  Not sure what was in there previously, but grinding was present before as well as after...

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is this a GL1 lube or a GL4/5 rated.....there is a big difference as the 4/5 is sheer rated for hypoid and not for the simple helical cut gears of your tranny...you should be running only a GL1 lube and that is available for approx. 15.00 a gallon at NAPA as of last month when this last came up...

 

not saying this is your answer..but this is the lube you need to be using....if oils is too thick..it may be preventing you gears from spinning down faster..

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I have a bit of a grind issue shifting into 2nd when I first start my P23.  If I let the car idle in neutral for a few minutes before taking off, I don't seem to have any problems upshifting.  I use napa 90wt GL1. Downshifting--well I've gotten pretty good at doubling clutching.

I'm going to try AMSoil 10w-40 and see if that improves things

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The viscosity is not the issue. Modern gear lube contains additives that are not brass and bronze friendly. Since your synchronizer components are comprised of those two metals, the proper oil is much more important than its thickness, especially if they are beginning to show wear. They are working as they should, evidenced by your report of better shifting after going into second. The synchro,s job is to stop the input shaft from spinning. It does this when you select second gear prior to first or reverse. Any drag between flywheel and clutch disc will spin the input shaft even in neutral. Your problem rests in an improperly adjusted clutch. You need to go back through the adjustment process to assure that with the clutch depressed, the pressure plate is completely releasing the friction disc. You maybe able to see this visually be fremoving the sheet metal dust shield at the bottom of the bell housing. If you can't effect the proper adjustment a trip to a professional might be in order. But you do need to remove that modern lube before any harm is done to the white metal bits.

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I have a bit of a grind issue shifting into 2nd when I first start my P23.  If I let the car idle in neutral for a few minutes before taking off, I don't seem to have any problems upshifting.  I use napa 90wt GL1. Downshifting--well I've gotten pretty good at doubling clutching.

I'm going to try AMSoil 10w-40 and see if that improves things

 

 

 

...Found this chart on, "bobistheoilguy", shows viscosity engine oil vs gear oil -( there are other differences)....GL1 gear oil has no sulphur odour and is available at NAPA in the US

post-296-0-25189400-1432659999_thumb.jpg

Edited by Ralph D25cpe

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Don,

I don't get any lurching forward or anything odd once I get the car into gear. If it wasn't for the grinding, it drives perfectly. The couple times I couldn't get it into reverse wasn't because of grinding but because the gear shift couldn't physically be moved into reverse and I don't want to force it in there. I think your correct, I probably still have issues with the clutch being fully engaged. now i put it 2nd before I put it in first to avoid the clutch grinding at stop lights. While in motion, if I drive it very gingerly, hold clutch petal in and slowly (6-8 seconds) place it into 2nd or third, I get little to no grinding. You mentioned I need to disconnect the free play rod and first set the over center turn buckle. I'm not exactly sure what you mean.. Is there any chance you can break all the steps down a little further for an amateur like myself?

Thanks!

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Hey Cerick305,

 

I had an issue like that too. Turned out it was the rear motor mounts being shot. When they compressed it threw the linkage out of whack. Easy way to check is to put the rear end on jack stands, jack the tranny about 1-2 inches up and start the car and shift thru all the gears. You can look at the mounts and they might seem fine but this way you will know for sure.

 

Joe

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Remove this free play rod and set it aside.

 

cfrod.jpg

 

There is a special tool used to make the over center adjustment. However if you do not have this tool the adjustment can still be made. The objective is to adjust the turn buckle until the spring pulls the pedal fully up with nobody touching the pedal and fully down when the pedal is depressed. This is easier to do with 2 people.

 

overcenter_spring.jpg

 

overcentertool.jpg

 

Once the over center spring is adjusted correctly then re-install the rod and the clutch return spring. Then adjust the free play using the rod.

 

clutchforkin.jpg

 

 

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