29 Clutch Problem

W

wildcat063

Junior Member
Hello

When the car is cold with the engine running and the car is stationary I can select select any gear without grinding the gears.
Once the car has been driven for around 30 minutes, when the car is stationary and I depress the clutch to select first, the gears will grind.

I have replaced the gearbox oil with 600W steam oil and this didn't fix the problem

What could be the problem and what could be the fix?
 
I'm assuming the clutch disengages completely as you don't say anything about crunchy changes when driving.
How soon after you depress the clutch pedal do you pull the gear stick into 1st? While the oil in the gearbox is cold, it is thicker and will slow down the gears quickly, allowing a silent engagement. Once it is warm (and thin), the gears keep spinning for a while and if you are too quick to engage them, you'll get a crunch.
Try waiting a while before trying to engage them.
When driving, that will mean paying attention at traffic lights so you are ready to go when they change. Modern motorists in their automatic cars don't pay attention. This is just one of those little things a good Model A driver has to learn.
 
The faster the idle speed the longer it takes for the gears to slow down in the warmer oil. Is the idle speed about 400 rpm? If faster it will take longer before you can get into gear as Synchro said, when the coil gets warmer and thinner.
On RHD cars the clutch pedal can go right down on a cold engine but catch on the exhaust clamp as things expand and the exhaust pipe moves with heat. This can cause insufficient clutch travel and grinding gears. One of our cars is like this and has to be carefully set to avoid this bottoming interference.
SAJ in NZ
 
I have turned the idle down to the point that it will stall and it doesn't fix the problem.
I will check the exhaust pipe
 
Aha Wilcat,I just saw you are a Kiwi like me and have a RHD car probably. Suggest to make sure you do not have the exhaust clamp interference problem when the motor warms. It is also possible that the pedal goes down and jams under the clamp when warm. Then you have no drive until you lean down and pull the pedal up, which can be annoying or scary, depending on where you are.
SAJ in NZ
 
You might trying to take a little free play out of the clutch.


You must have some free play but taking a little out will allow the clutch to release a little more.


I have one of my Hot Rods that has marginal clutch travel and I have to adjust it with very little free play. If not, it will release fine when cold but once warmed up, the clutch will drag just a little with the clutch pedal fully depressed.


My experience,


Chris W.
 
wildcat063 said:
I have turned the idle down to the point that it will stall and it doesn't fix the problem.
I will check the exhaust pipe
Click to expand...

When I made my first post on this, I didn't realise that were RHD. Maybe I should have read more closely.
I agree with the comments about the clutch pedal maybe hitting the exhaust clamp - a real PITA and yet another design flaw in the Model A. There are clamps available which are made for RHD cars (though I have seen them advertised in the US too) which only use bolts - no nuts on the back. That makes it easier to orient the clamp so that the pedal goes all the way down but you still have to be aware of what you are doing. The gap between the clamp and the block is not very big and the pedal has to go through it.
 
On my wifes Tudor there is no nut and bolt on the clamp. Just a stud I brazed in. The pedal hits the clamp itself but only when hot. So when set up on a cold engine with clearance, it catches on the clamp after the manifold changes shape when hot.
After finding the pedal jammed down past the clamp as mentioned in my previous post, I decided to re set clutch fingers and free play so that clutch disengages when bottomed on the clamp. This works well, but may not be applicable to all cars,, since there is something odd in this cars clutch set up anyway. Wth the specified clutch finger clearances this particular clutch wĺill overthrow and make clattering noises if the pedal is fully down- that is pushed down past the exhaust clamp.
Who knows what has been done to some of these cars after 90 years!
SAJ in NZ
 
SAJ, A stud brazed into one side of the clamp is one way to go - and a good one. I use a pair of helicoils in one side and a bolt through the other. I figure we do the same thing but different!!
I've had to tweak the pedal a smidge once or twice but I haven't adjusted the clutch to compensate for the reduced pedal movement. While it's working, I'll leave well enough alone.
 
Synchro your method is neater than mine. I also use brass nuts which I thought might be good, but changed my mind recently when they will only torque to about 25 lbs ft, especially on the manifold. I thought they would be less likely to seize on the studs, but the low torque availabl for brass is not good, I think.
I use copper/lead/tin/MoS2 antiseize anyway. (Rocol J166 which I used to manufacture)
Regards
SAJ in NZ (Actually in Hawaii at the moment!)
 
A further thought. I have rubbed the manifolds down a number of times on 30 grit abrasive paper glued on a granite surface plate. Original Ford manifolds are very soft and it is easy to take 25 thou off in a session to flatten them. This moves the RHD exhaust clamp further in towards the clutch pedal, making interference worse each time it is done.
Others mill off them at an angle to improve the clearance, but I never have the time to set up in a mill. Hand fettling is very quick.
Maybe when I retire at 95 I might take the time!!
SAJ IN HAWAII on holiday
 
SAJ, There was NO need to add that last line!! ;)
On one of my cars, I'm down to a marginal clearance but I didn't think of surfacing them at an angle then - that came later but I'll make sure next time. To prevent seizing, I use Molykote 1000 (Dow Corning). I looks to have a fair bit of Cu in it too. Always been good and I don't think I wiill ever finish the tin
 
Gents, this is an interesting discussion but in 50 years of driving my Tudor I have never had this problem. My clamp is just angled slightly & plenty of room for the clutch pedal to move down. I have the separate bolts & brass nuts. Perhaps many of the old exhaust manifolds are badly distorted & have been shaved too many times.
Cheers - Tom in NZ.
 
The issue was that the clutch pedal was hitting the exhaust clamp (Right hand drive car).

I still have issue that I have to double the clutch on the up shifts.
Should I have to do this?
I have 1/2 and inch of clutch pedal travel (measured at the pedal) before resistance. Should I adjust this to be 1 inch?
 
Double de clutching[ & reving slightly at neutral] when shifting into 2nd from top is normal. Free play is 1" .
Glad you got your other problem fixed. Nice weather here in Sth NZ for getting the A out. Cheers.
 
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