Power Shift or Transmission issue?

[GTfastbacker]

We have now test driven our new old Dodge 300mls.

(41 D19 3-speed power shift)

 

I have the following problem when changing gears:

The gears change very easily thanks to the power shift. However, it is almost impossible to change from 1 to 2 without the gears scratching slightly. It doesn't matter whether you use the clutch twice or pause for 2-5 seconds. It almost always scratches slightly. It is exactly the same when you downshift from 3 to 2. Intermediate clutch, intermediate gas, long pause, the same problem. Sometimes it works, but usually not.

 

I also have the impression that the travel of the gear lever for 2nd gear is quite short and sometimes 2nd gear jumps out, especially when downshifting.

 

Before I rip apart the whole power shift mechanism or open the gearbox, here is a question for the specialists: where should I best start looking?

 

Thank you

Joe

 

PS: sorry for my sometimes stupid quest. I habe to learn a lot 😊

Edited July 14 by GTfastbacker

[Sam Buchanan]

I'm not familiar with the power shift, but if the transmission itself is the same as the standard three-speed a change in transmission oil may fix the crunchies. I had a crunchy 1-2 shift until the trans warmed up but a change to RedLine MTL resulted in silky smooth shifts in all gears at all temps. The oil is more expensive than the generic stuff but if it results in smooth shifts with no additional work on the trans it is a bargain.

 

 

 

[plymouthcranbrook]

I agree with the use of Redline. My 52 Plymouth would crash going into second gear unless you shifted very slowly. Now no further issue. Also make sure your linkage is adjusted correctly as your remark about a short throw to second makes me wonder if that is part of your problem

Edited July 15 by plymouthcranbrook

[Sniper]

The OP is in Germany, not sure if Redline is readily available there.

[GTfastbacker]

10 hours ago, Sam Buchanan said:

I'm not familiar with the power shift, but if the transmission itself is the same as the standard three-speed a change in transmission oil may fix the crunchies. I had a crunchy 1-2 shift until the trans warmed up but a change to RedLine MTL resulted in silky smooth shifts in all gears at all temps. The oil is more expensive than the generic stuff but if it results in smooth shifts with no additional work on the trans it is a bargain.

 

 

 

 

Great, I will try that !

Here is a special Racing Oil online shop where I can buy it.

 

While we're on the subject of oil:

According to the manual, the water pump must be lubricated with water pump grease.

But I can't find a grease nipple anywhere on the pump?

Is it possible that a newer model has been installed that no longer needs to be lubricated?

 

And: is there another "MMO" recommendation for the Rear End (Axle) Oil?

 

Tank you!

Joe

 

 

 

Edited July 15 by GTfastbacker

[Sam Buchanan]

Yes, if no grease fitting on the water pump you have a newer pump that doesn't need lubrication.

 

Currently available GL4 or GL5 gear oil will work fine in the rear axle. There is a small vent on the axle housing, check to make sure it hasn't been covered with road gunk.

Edited July 15 by Sam Buchanan

[Sniper]

Make sure whatever lubricant you get for the rear axle said hypoid gear lubricant. That's designed specifically for the sliding stresses in a rear axle. Do not get something that says manual transmission lubricant only

[FarmerJon]

On 7/15/2024 at 2:10 AM, GTfastbacker said:

 

Great, I will try that !

Here is a special Racing Oil online shop where I can buy it.

 

I expect Pentosin makes a comparable Manual transmission oil, you could call them and see if they have a recommendation. I belive they are German based. 

There may be a different procedure for adjusting the power shift, but here is a little about checking and adjusting the standard shift linkage. It never hurts to check that everything is set right, as somethings can sag and bend over the decades.

[GTfastbacker]

i changed the Oil using the redline MTL.

The scratching while gear change is better but not gone.

I think i need new synchro rings? are they available?

 

Thank you 

Joe

 

 

 

 

[Sam Buchanan]

The MTL may get better with some added miles. Be sure your clutch doesn't have any drag when the pedal is depressed.

[Los_Control]

On 7/14/2024 at 1:29 PM, GTfastbacker said:

sometimes 2nd gear jumps out, especially when downshifting.

If you were to search old dirt track, circle track racers ..... It was common to create a loop from the dash to the floor shifter to hold it in 2nd gear.

 

Just one of those things that the syncro's would wear out and they would pop out of gear.

Since these were dirt track racers, they would race down the straight sections and just when you would want to grab 3rd gear .... you would enter a corner and need to let off the gas.

 

When this happens, worn syncro's would cause the transmission to pop out of gear.

So serious racers created a hook to hold the gear shift lever in 2nd gear so it would not pop out ..... These were dirt track racers that in any race the car could be destroyed.

The transmissions worked just fine for racing and instead of replacing the syncro's they just tied the shifter up.

 

I'm just saying if your transmission is popping out of gear when you decelerate .... tie it to the dash or rebuild it .... nothing new going on here.

[rustyzman]

If you end up digging into the internals of the transmission, after you have exhausted all external adjustments of course, there is another item that you need to look for.

 

A manual transmission jumping out of a gear can be quite likely too much gear end-play.  The synchro itself can be worn and cause a rough engagement of a gear for sure.  But a worn synchro ring itself should not cause a transmission to jump out of gear.  Once the gear is engaged, the synchro ring is no longer really doing anything to hold a gear's engagement.  It is just a friction clutch to help align all the engagement teeth of the various components so they slide together smoothly.

 

A common older manual trans problem is that the thrust face of the gear wears down against the next component on the shaft and starts to create excessive endplay.  This is prevalent in bevel gear transmissions, because the driving action of the gears naturally forces the gear up against whatever is next to it and those faces rub together if they are not rotating at the same RPM.  Once you have enough endplay, the engagement teeth of the gear that are engaged with the sliding ring shift ring on the shift fork start to engage less and less.  Eventually, they start to slip out and you pop out of gear.  The gear face may even look like it has a nice machined counterbore on one side, but in fact, it is just worn that way. 

 

There are of course other sources of this problem too.  The shift forks can also be worn and prevent you from getting full engagement of these same parts, as well as the engagement teeth on the gears or even the sliding shift ring.  Once it is apart, some measurement with feeler gages and visual inspection should reveal your source/sources.  A lot of cars were run with little maintenance or low on fluids for a long time in their lives.  A lot of wear can happen that way.

 

All of this again is suspect only after you have eliminated all issues with the linkages from top to bottom.

 

And Redline MTL is wonderful stuff.  It has revived many weak transmissions.

Edited August 11 by rustyzman

[jpellican]

what weight mtl? gear oil are you using?

[Sam Buchanan]

48 minutes ago, jpellican said:

what weight mtl? gear oil are you using?

 

75W-80

 

[greg g]

Gotta ask.  What do you mean by power shift?  I met a fellow who had a 42 Chrysler  that he said had a vacuum shifted trans mission.  He said they were made for service men who returned home with combat wounds that would not them to use clutch and or brake at the same time, so vacuum subplanted muscle to shift and steer with lose of an arm or depress the clutch.  Or are you referring to the dual range semi automatic with 2 gear sets in each range.

Edited August 17 by greg g