Fluid drive in heavy stop and go traffic

[Bbdakota]

Is there concern in overheating the fluid drive with heavy stop and go traffic if I leave it in gear and don't clutch? I'm talking cruisin the coast type traffic where sometimes it may take an hour to go a mile. In the past, I've clutched and put the car in neutral but my foot gets sore from that much clutching. I try avoiding the heavy traffic but the car has a new radiator and new carb, I'm more confident and may venture into traffic. The next biggest concern for me would be the fluid drive. 

[Doug&Deb]

The fluid drive should hold up fine. Cars with the M6 were used as taxis back in the day. I’m hesitant to drive mine in heavy traffic also but I’m more concerned about engine overheating.

[Merle Coggins]

I've never had an issue with my FD in those conditions, but then again there's no temp gauge in there so I have no idea how hot it was getting. However, this summer I got caught in a major traffic jam up in St Ignace, MI and after a half hour, or so, of stop and go (creeping ahead) my engine started running hot. I had to use the clutch and elevate the RPM to get more air flow through the radiator and cool it down. That's the first time I've had that issue.

[Bbdakota]

The 2 responses so far are encouraging. Both referenced the engine running hot. I'm glad to say I've addressed engine cooling by installing a modern aluminum radiator. My engine temperature won't get over 180 with a 160 thermostat. 

[chrysleritis]

The fluid drive temp should be no problem. The radiator and cooling system, if in good condition, should also be no problem. I have had problems with fuel flow/vapor lock/heat soak in stop and go, parade type traffic. Many of our cars are now missing the heat shields that kept the fuel pump, filter, and carb base cool, and over the years, owners may have gotten a little sloppy with fuel line routing in the engine compartment. Depending on your setup, you might consider worrying about this issue. Of course, the real problem in heavy traffic is that someone will dent your big fenders. Driving would be a lot more fun without all these other knuckleheads on the road.

[James_Douglas]

I have to disagree with the other posters. I have seen, I would have to dig to find it, a MOPAR service note that says one should not keep the car in gear "on the coupling" more than 5 minutes.

 

I had a friend with a 1946 Town & Country CV sitting next to me in my 1947 Desoto and we were waiting for 15 minutes to get positioned in a car show. His engine overheated and the fluid coupling staring hot, you could see some smoke of oil flashing off the house and coming out the side screens!

 

The fluid coupling has cooling fins on it. If it does not move, no air, no cooling. 

 

If stuck in traffic at the Golden Gate or Bay Bridge heading back home to San Francisco, I always clutch it, if not, you can see the engine start to warm up and it is 65F here in SF.

 

That is one reason why in the 2020 - 2021 rebuild of the Desoto, I will go with a different transmission. I don't want to worry with getting stuck in traffic traveling around the USA in this car.

 

[Dodgeb4ya]

I've never had any fluid drive over heating/smoking issues in any of my Chryslers.

This includes both inline six and inline eight cylinder cars. The fluid coupling has fins to help cool it...that's what they are for. There is A lot of air movement in the bell housing at idle because of those fins on the FD coupling.It is always spinning clutch in or clutch out.

Slighly low FD oil level could cause a heating  issue.

In stalled traffic engine temp rise is  the issue.

Edited October 3, 2019 by Dodgeb4ya

[chrysler1941]

4 minutes ago, Dodgeb4ya said:

I've never had any fluid drive over heating/smoking issues in any of my Chryslers.

This includes both inline six and inline eight cylinder cars. The fluid coupling has fins to help cool it...that's what they are for.

Slighly Low FD oil level could cause a heating  issue.

In stalled traffic engine temp rise is more the issue.

 

I second that. Never any problems with fluid drive.

[Merle Coggins]

3 hours ago, Bbdakota said:

The 2 responses so far are encouraging. Both referenced the engine running hot. I'm glad to say I've addressed engine cooling by installing a modern aluminum radiator. My engine temperature won't get over 180 with a 160 thermostat. 

 

My engine usually doesn't get over 180-190ish, unless I''m on a long hard uphill climb. But with that constant load at very low RPM there wasn't enough air flow from the fan to keep up with the cooling demand. Removing the load and raising the RPM, to increase air flow, brought the temp back down.

Edited October 3, 2019 by Merle Coggins

[Doug&Deb]

I believe the owners manual does recommend de-clutching at long stops. We are all guilty of babying our cars. We forget that they were once someone’s daily driver in all kinds of weather and traffic conditions. You should not have any problems with the fluid drive but a little prudence goes a long way.

[normanpitkin]

I drove my 48 new yorker 400 miles this weekend ,as long as the fd fluid level is correct it has never been a problem.Vapour lock is the enemy here but only after driving for 3 hours or so!

[Doug&Deb]

There’s a journalist named Jon Robinson that uses a 50 DeSoto coupe as his daily driver. I believe it’s his only vehicle. It’s a shame he’s not active on this forum. He would be a treasure trove of information on how to use our cars in modern traffic.

[Loren]

Honestly, I'd worry more about the brake light bulbs burning the lens on your tail lights.

My favorite year Plymouths have plastic lenses and those bulbs get hot!

Sitting with your foot on the brake for extended periods taxes more than just the Fluid Drive.

I'd kick it out of gear and apply the hand brake.

Just saying, consider the cost of replacement lenses.

[Jerry Roberts]

The LED 6 volt bulbs don't get hot , use less electricity , and are brighter too . 

[Bbdakota]

11 minutes ago, Jerry Roberts said:

The LED 6 volt bulbs don't get hot , use less electricity , and are brighter too . 

That's an idea! Although I  added turning signals so I'd have to get the correct flasher.....I think my car has glass lenses....not sure, I had them out to replace the round reflector. 

[Sniper]

I recall reading, decades ago, about a story where an FD equipped car was losing a seal causing a leak.  It belonged to some wealthy guy with some inside pull at Chrysler who complained about it.

 

So they put an engineer on it.  It was a chauffeur driven car for the man's wife.  After talking to the chauffeur he found the issue. Seems the chauffeur would be on the FD while the lady was doing her shopping.  Reason he'd do that is that it was winter somewhere up north and it kept his feet nice and warm.  The seal in question would eventually fail and cause the issue.  The engineer ended up redesigning the seal, I think it  was more of a materials change than anything else.  And that solved it, the chauffeur could keep his toes toasty and the seal could handle it.  But that was back in the day when engineers actually had real world experience and understood that the customer will do what the customer does and you had better figure out how to fix around that.

[Bbdakota]

4 hours ago, chrysleritis said:

The radiator and cooling system, if in good condition, should also be no problem

If in good condition was the problem, although it never run hot, the temperature would creep up until the gauge was to the red. I didn't realize how inefficient it was until I put an aluminum radiator in it.

[Jerry Roberts]

1 hour ago, Bbdakota said:

That's an idea! Although I  added turning signals so I'd have to get the correct flasher.....I think my car has glass lenses....not sure, I had them out to replace the round reflector. 

If you keep conventional bulbs in the front , you won't need a special flasher . Only if all of the turn signal bulbs are LED .  Also a rebuilt motor is tighter and runs hotter . 

[keithb7]

A stimulating topic! I’ll say my part. 2 things:

 

I have the fluid torque drive in my ‘53 265 Windsor. The engine oil is pumped out the rear of the block  and into the torque. Then cycled through and dumped back in the crankcase sump. Continuously! It takes about 13L each time to change my engine and torque oil.  I suspect this system will stay cooler in stop and go LA or San Fran traffic. I must admit that on really hot summer days, I’ll clutch in at a red light. Not sure why really. It just seems helpful. 

 

Have you ever had your old Lockheed brakes staying on? It happens and its not fun. My ‘53 was new to me and I had no idea. In the beginning I noticed the rear brake lights were staying on. When I walked away from the car I’d see them. I started pulling the rear 6V bulbs to save battery power. That was 2 years ago and if I recall those 6V bulbs were dang hot!  Burnt my fingers pulling the bulbs. So ya they get hot. Since then I rebuilt my brake system and all is well. 

Edited October 4, 2019 by keithb7

[Dodgeb4ya]

The master cylinder piston is not fully retracting..pedal free play less than a 1/2" ?...or swollen or incorrect master cylinder piston cups if m/ c is or was rebuilt.

The piston will not return back all the way holding pressure on the brakes.

You need to check that the piston is not blocking the compensating port(smaller) of the two holes in the mc fluid chamber.

[Loren]

For years I worked on Swedish and German cars, I never had to adjust the pedal push rod.

Then I rebuilt the brake system on a Morris Minor. I was shocked that the manufacturing tolerances finally caught up with me.

Happily I knew what to do. After that experience I got a little more fussy about that adjustment.

Apparently the Chrysler engineers who wrote the shop manuals I have were fussy about the pedal adjustment too, because they describe what happens it each point in the pedal depression. 

[James_Douglas]

Well,

 

I happen to know Jon. We have swapped technical stories for years. Although, I have not talked with him in quite some time. I like Jon use the 1947 Desoto Suburban as my daily driver here in San Francisco and around the bay area. This car is run hard to keep up with modern traffic. 

 

I stand by my previous post. There is documentation out there that states that you should not sit at idle or close to it with a fluid coupling. A torque converters has the oil moving in and out of the thing and has not comparative value.  Also, if moving along at more than 5 MPH that also has no comparative value.

 

Interestingly, I also saw a tech note as to test a fluid coupling and clutch to see if the clutch was slipping or fluid coupling not stalling. The tech note said to run the car up against a loading dock or such (with rubber in my case), then go to full throttle and note the engine max RPM. If the RPM went over xxx (I don't remember the number), then something is slipping or not properly stalling. That tech note also warned to only do this for less than 1 minute or else damage to the coupling could result.

 

One final thing. As far as I know, and I could be wrong, all the fluid couplings used a carbon seal and nothing else. If someone has some data to the contrary, I would like to know. One of the issues with the carbon seal is that when you take the transmission out and allow the little flywheel to move it can crack that carbon seal. Hence the recommendation to use 3 or 4 little wood wedges between the little flywheel and the fluid coupling case with bailing wire to hold them in place before your take out a trans or while you have a fluid coupling out of the car.

 

James.

Edited October 4, 2019 by James_Douglas

[Bbdakota]

4 hours ago, James_Douglas said:

Well,

 

I happen to know Jon. We have swapped technical stories for years. Although, I have not talked with him in quite some time. I like Jon use the 1947 Desoto Suburban as my daily driver here in San Francisco and around the bay area. This car is run hard to keep up with modern traffic. 

 

I stand by my previous post. There is documentation out there that states that you should not sit at idle or close to it with a fluid coupling. A torque converters has the oil moving in and out of the thing and has not comparative value.  Also, if moving along at more than 5 MPH that also has no comparative value.

 

Interestingly, I also saw a tech note as to test a fluid coupling and clutch to see if the clutch was slipping or fluid coupling not stalling. The tech note said to run the car up against a loading dock or such (with rubber in my case), then go to full throttle and note the engine max RPM. If the RPM went over xxx (I don't remember the number), then something is slipping or not properly stalling. That tech note also warned to only do this for less than 1 minute or else damage to the coupling could result.

 

One final thing. As far as I know, and I could be wrong, all the fluid couplings used a carbon seal and nothing else. If someone has some data to the contrary, I would like to know. One of the issues with the carbon seal is that when you take the transmission out and allow the little flywheel to move it can crack that carbon seal. Hence the recommendation to use 3 or 4 little wood wedges between the little flywheel and the fluid coupling case with bailing wire to hold them in place before your take out a trans or while you have a fluid coupling out of the car.

 

James.

Thanks James, I believe I'll follow your advice and minimize the amount of time I sit on the coupler. Certainly would be the safest option. 

[Sniper]

40 and later have the carbon seal, 39 didn't. 

fluid drive.pdf

[James_Douglas]

18 hours ago, Sniper said:

40 and later have the carbon seal, 39 didn't. 

fluid drive.pdf 278.61 kB · 3 downloads

 

I would like to see a photo of one. James