Flathead Clutch Slipping - Help

I searched the forums, but didnt find anything directly linked to my problem - So, here it goes:

I have a 39 flathead in great shape with brand new clutch plate. I have a 39 three speed trans that looks nearly new when we opened it up.

Now that its all in and the 36 truck is nearly done we have two problems:

1. Gears grind (not all the time) - from what I read on the forums this is common - so, should I worry?

2. When we 'get on it' in any gears, the clutch is slipping. What could be causing this? It feels pretty strong, but you can still tell it is slipping.

For the record, we did have a rear main seal leak that was pretty bad and probably got on the clutch plate. Maybe that is the cause of the slipping? Will it go away the more I drive it?

Thanks for your support and help. Casey

 

First question for your road to recovery. Is the clutch adjusted correctly with about 1/2" free play at the pedal? That means no tension at all on the clutch linkage. First impression is that the clutch is not fully engaged and would lead to the slip . The gear grind, when does that happen, up shifting, its not like a modern 4 speed. Top load three speeds dont like quick shifts and down shifting into first on a roll is not any better.
Your turn.

 

If you had a bad oil leak it's almost a given you've got oil on your plate. It wont go away, only cure is replacement. You might get away with burning the oil off with a propane or a/e torch.... your call.

 

There is also the possibility that your pressure plate just aint built for the new umph. and oil saturates the disc, so though it might get better, if thats the cause it probably wont go away.

 

Someone suggested I check the clutch plate and bearing release clearance and make sure it is 1/16th of an inch.

I will also check the clutch free play.

Sounds like if I have oil on the plate, then I may be hosed - ie, replace the plate.

I will check the bearing release clearance and clutch free play next - maybe those need adjusting and it will help. I appreicate the feedback and ideas.

As for grinding gears, its not too bad 2nd and 3rd. Since there is no sync on 1st and R, I have read its best to put into 2nd first and then shift to 1st. Most people I talk to think I have a normal situation with an old topload 3 speed like this??

Casey

 

That's how my '51 F1 3 speed acts also....I think it's normal.

 

If you think you oiled the disc up just remove the transmission clutch inspection cover, depress the clutch to release the grip and spray the disc, pressure plate and flywheel surface with Brake Kleen to remove the oil residue from the face surface. You might want to due this in a couple steps by rotating the engine over 180* to clean all surfaces. You should block the clutch to the depressed position to let the disc air dry after spraying and allow the solvent to evaporate, This should get rid of most of the oil film and give you a clean dry flywheel and pressure plate surface with out having to remove the engine and replace the disc.

If you are grinding when up shifting or down shifting 2-3 something else is wrong or worn out. Sounds like you have more than one issue.

 

oil leak to clutch probably causing prob. as said earlier, check free play.

 

I had the same problem with a 1950 Mercury flathead. I have an S10 clutch plate and an S10 5 speed and a hydraulic clutch.
When I first got it running the clutch slipped until I had a street race pressure plate built. Now everything works fine.

 

just pull up to a tree and let out the clutch. smoke that oil off... just joking.
that is what my Grandpa told me they did in the old days. he is 96

 

oh yea forgot.. double clutch. like shifting old semi tractors.......

 

OK - we are going to try the ideas here. Will let you know how it goes. Again, many thanks for the suggestions. Casey

 

If you take it apart check the front bearing seal in the transmission it may be letting gear oil out on the disk.

 

**** Sparado's idea is definitely your first move. Not sure about 29AV8's grandpa.... although I have heard of that being done.

 

sounds like to me you have the disc in backwards

 

You only have to double clutch into first on a rolling stop. Its becomes second nature after a little practice.

 

OK - we did the Brake Kleen and it seems to have helped, but there is still some slipping - maybe it will take a couple of days to dry out? The grinding issue was me just learning the sync on an old 3 speed. The slipping is when you "goose" the gas in 2nd or 3rd - it doesnt jump with the engine throttle right away, but seems to slip. Thanks! Casey

 

The question still IS !! Did you check for bearing clearance/freeplay??

 

I had a 39 Sdn yrs back with a seal leak and a slipping clutch. I talked to an Old Timer, he sent me to the drug store for some powder alum. Removed the inspection plate and tossed some in and worked the clutch pedal a few times and tosed a bit more in, WOW, the clutch was ether in or out, NO SLIP. Worked well. Fixed the seal and never replaced the clutch. Iceman