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Fluid Drive Issues


mrahc

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As the title states, I'm having issues with the fluid drive in my 50 Coronet.  It's been slipping on me for a while, under acceleration and uphill.  My fist attempt at a solution was to drain the old fluid and replace it with new ISO 32 hydraulic oil.  This didn't seem to help anything at all.  My next attempt was to remove some of the fluid and, in its place, top it off with some Lucas Stop Slip.  This seemed to offer a noticeable improvement the first time I drove it, but the improvement didn't last very long. 

 

On a road trip this weekend, she started slipping pretty badly while going up a large hill on the highway.  When I pulled over to check everything out, I saw that fluid had started pouring out.  I pulled out the plug to try topping it off before continuing down the road.  There was noticeable pressure relieved when I pulled the plug away, and fluid was spewing out of the unit.  To avoid losing any more, I plugged it bag up and let it cool off before continuing on my way, with the slipping now worse than before, but still obviously drive-able.  200+ miles later, there was still a large spot on my driveway the morning after I returned home.

 

My goal for this winter is to swap to an overdrive transmission, but there are still some shows I need to get to this summer.  Is there any way to easily lock up the fluid drive unit in order to make driving the car more tolerable?  I really enjoy the three speed, but the hydraulic coupling is a nightmare.  Any other suggestions are greatly appreciated.

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24 minutes ago, mrahc said:

As the title states, I'm having issues with the fluid drive in my 50 Coronet.  It's been slipping on me for a while, under acceleration and uphill.  My fist attempt at a solution was to drain the old fluid and replace it with new ISO 32 hydraulic oil.  This didn't seem to help anything at all.  My next attempt was to remove some of the fluid and, in its place, top it off with some Lucas Stop Slip.  This seemed to offer a noticeable improvement the first time I drove it, but the improvement didn't last very long. 

 

On a road trip this weekend, she started slipping pretty badly while going up a large hill on the highway.  When I pulled over to check everything out, I saw that fluid had started pouring out.  I pulled out the plug to try topping it off before continuing down the road.  There was noticeable pressure relieved when I pulled the plug away, and fluid was spewing out of the unit.  To avoid losing any more, I plugged it bag up and let it cool off before continuing on my way, with the slipping now worse than before, but still obviously drive-able.  200+ miles later, there was still a large spot on my driveway the morning after I returned home.

 

My goal for this winter is to swap to an overdrive transmission, but there are still some shows I need to get to this summer.  Is there any way to easily lock up the fluid drive unit in order to make driving the car more tolerable?  I really enjoy the three speed, but the hydraulic coupling is a nightmare.  Any other suggestions are greatly appreciated.

Have you checked the clutch not slipping?

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My initial thought was the clutch, but I would have smelled it.  And with the size of the hill that I was spinning up, it would have left me in a cloud of smoke and unable to continue driving.

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Once again. Do you have any Clutch Judder?

Leakage will wet down a clutch and cause slippage the Front Seal or Fluid Seal are possibly bad but it sounds like Clutch Disk slippage or Judder.

Smell has nothing to do with a proper inspection of the Clutch Housing area.

Just my humble opinion

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The clutch does not shudder at all.  I realise that the fluid that has now leaked from the unit has potential to cause the clutch to slip, but I've been having this issue since well before it started leaking.

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I agree with the clutch slippage theory, but it also sounds like you have a failed seal in your FD unit. Once you get oil on the clutch disc it will slip, and won't necessarily smell.

 

When I built my truck I got solvent on my clutch disc when cleaning everything. I brake cleaned it and hoped for the best. All was good for 2 or 3 years, then I would notice slippage in 4th gear when under a load. The slippage continued to get worse throughout the summer. That winter I pulled the clutch and FD unit. I had my clutch, and clutch disc, rebuilt by Fort Wayne Clutch. I also pulled the driven plate from the FD unit and had it surfaced by a local shop. (the same shop I took the clutch to, and they sent it out to Fort Wayne Clutch for rebuild). After reassembly it's been slip free to this day...

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Ditto.  Other than the fluid drive probably leaking fluid onto the clutch to cause it, a slipping clutch is not a fluid drive issue, it is a clutch issue.  Two different things.  I've dealt with two cars with slipping clutches, neither had any clutch chatter to forebode a future problem, and neither smelled at all.  If your clutch disc has gotten oil on it, adjustment is pointless.  It may ease the problem, but you've still got a bad clutch disc.

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As someone who has used a fluid drive in a daily driver for 18 years, they can be fine. I have had a seal go, even one that was supposedly rebuilt.

 

Once you get one that is good and take care of it, it will last a very long time.  Since I run mine in a Desoto Suburban, with the very high curb weight, if it will live in that car and the hills of San Francisco from a dead stop, it will live in anything else. A few thoughts.

 

  • Read my long winded paper on fluid to use so you get a good understanding on how the thing works.
  • If one goes to take it out, make 4 wooden wedges with a slot on the large end and tap them in light between the flywheel and the coupling BEFORE you take a transmission out. What you do it take the lightly the 4 blocks then run a length of bailing wire around them to keep them in place. You have to spin it around to do this.  You do this for shipping and on the installation as well. If you do not, the flexing of the plate can crack the carbon seal and it will leak.
  • The special products shop at DACCO transmission was closed down about 24 months ago then they went bankrupt and was purchased by another company. So as of today, I do not know of anyone that can cut open a fluid coupling and replace the inner bearing. The pinion bushing and seal can be done from the outside, but that bearing requires it to be cut open.  The issues, unlike a torque converter, is that without a flex plate, the two sides of the coupling have to be perfect when welded together. Even a couple of torque converter shops I have talked with say they do not have the jigs to do it. They could make up a jig, but the cost would be in the 3K to 5K range for the first one.
  • NEVER open the plug on a fluid coupling unless the engine has been off for at lease 4 hours.
  • If you pull the plug and take a Popsicle stick, you can rotate the inner hub around you will see some larger holes than the many smaller ones as you spin it around. A local three generation repair shop, Bob Senior is 85 and looks better than most 50 year olds, told me that if the thing fails on the road, to have a correctly sized bolt in the glove box to fit the threading in the outer shell oil plug (the plug TPI) and grind lower end of the bolt to just fit the larger inner hole size, the better the fit the better as you want no slop. On the road, take the plug out and rotate the thing down to 6 O'clock and drain out all the fluid, on the ground if hung out someplace.  When it is all out, rotate the unit back up to the floor board hole to get at it. Then run bolt, with a copper washer under the head into the coupling and the inner hub large hole. The inner hub is the part that is attached to the transmission pinion. The outer shell is the part that is attached to the crankshaft. The bolt "connects" the outer (the crankahsft) to the inner hub which is connected to the transmission. Use a VERY good grade 5 or 8 bolt.  Once done, you can drive it like a three speed stick.

 

Good luck, James.

 

PS. If some of the above reads weird...I am home after two surgeons spend 4 hours in my lower back.  My head is not quite clear and I am looking at a month stuck in our flat here in SF.

Edited by James_Douglas
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