Unusual Transmission problem '26 Touring

[Chris Bamford]

1926 Touring, sudden-onset problem of slipping in high, but low and reverse are fine. Peeked inside for clues and found the clutch fingers quite loose. Had the clutch spring broken in service? Careful inspection showed it was intact, but...

After much puzzling I finally noticed that the clutch spring and spring cup were pushed right back the half-inch or so to the 4th main. This took a lot of tension off the spring and is doubtless the reason for slipping in high.

So what happened? Pin sheared in two places? Sounds unlikely to me and an engine-builder friend has never seen such a failure. The spring cup and the two 180° holes look just fine with no signs of trauma.

Anyway, I'm resigned to pulling the power plant out for inspection and repairs, but in the meantime I welcome any speculation about what's going on here.

[RajoRacer]

Where is the rest of the spring ??????? Something (spring?) came from together !

[speedytinc]

You pose an interesting question/problem.
The clutch fingers will be sloppy loose with the clutch disengaged.(lever back)

So I mocked up some spare parts. I doubt the pin sheared. Never seen this & there isnt enough force to do this.
The spring retainer cup normally sits very close to the ball cap. If the pin was sheared or gone, the cup would be rubbing on the ball cap. There would be NO gap. I see a gap. If the pin was gone, the cup rubbing making chips, You could see some of the pin hole in the output shaft under the spring @ the cup base.

Sometimes a slipping clutch is just a slipping clutch.

Do you have the original all steel clutch disks pack? That excludes a softer lining wearing away.
Check all clutch linkage.
Does your parking brake go all the way forward & easily clear the throw out arm adjusting bolt, not tending to be pulled back from a tight parking brake adjustment?
Low pedal linkage in spec?
Follow the service manual. Maybe a slight finger adjustment is needed as referred to in the manual.

With the clutch engaged(parking lever forward), expect a spring length of 2" & the throw out bearing 13/16" away from the shaft base.
All 3 fingers must provide equal pressure as much as is possible with 1/2 turn adjustments.
(A wide deviation is an indication of a problem, be it minor or major.)
Thats a starting point. Tighten the finger screws 1/2 turn @ a time until the slipping ceases. See the service manual.

[Mike Silbert]

Before tearing it apart where is the clutch adjustment set?
The clutch only locks up in High gear, its released everywhere else so the symptoms of a slipping clutch sound normal.
There are 3 fingers inside, a link outside, emergency brake lever and a band adjustment in the equation.
I've seen this happen after a band adjustment before by accident.
Verify all that is proper before digging deep.
I expect that an adjustment will get it going again unless the clutch disks died, spring died, or linkage broke.
You are also likely to have a weak spring, if you get all the way to it.
Maybe you will get lucky and and it is easy.

How to test the clutch without driving:
1) Chock the wheels (block the car from moving)
2) Put brake lever all the way forward to lock it in high gear.
3) Engage the hand crank in the horizontal position.
4) Stand on the crank to apply 150 to 200lbs of pressure. You are simulating the 80 to 100 lbft of torque from a stock engine.
5) Crank moves then the clutch slips, Crank does not move you are good. Car moves then chock it better and repeat test.

I suspect it will be coming apart, maybe not today.
Mike

[Chris Bamford]

Steve, here is another photo with the hand lever back and spring compressed .

Near as I can tell, the two spring ends (yellow) are where one would expect and the spring coils evenly spaced. And, while it's hard for me to see, it appears the forward end of the spring is riding tight to the back face of the clutch collar, also as one would expect (blue arrow).

John, my assumption of roughly 1/2" clearance between spring cup and fourth main is from my '24 Speedster, photo below. Pink arrows indicate that gap. Agree the above photo looks like a gap, but in the photo below, I see a lip of sorts at the small diameter of the fourth main (green arrow) that could give the illusion of a gap. One can also clearly see the end of the pin in the cup hole, something not showing in the problem transmission.

I can't adjust the fingers to 11/16 clearance without reducing their engagement pressure to almost zero (hand lever forward).

The clutch spring height compressed (hand lever back) is 2"+/-.

All steel clutch in this car. Hand lever and bands set correctly. You and Mike are right to make sure I understand the basics before going much further, and thank you for that, but I have maintained and driven Ts for 30+ years and rebuilt a several engines as well. I'm pretty sure the other adjustments are at least close enough.

And speaking of adjustments, we should remember this was a "sudden-onset" problem — a gradual drift of adjustments is likely not at play here.

Mike, that is a very clever static clutch test. Thank you. As it turns out, with the hand lever forward and wheels chocked, and my 210 lbs bouncing on the hand crack, I couldn't get a bit of movement. Zero. Now I'm really puzzled.
_ _ _ _ _

Is anyone in a position to look inside an assembled transmission to eyeball the clearance, if any, between the rear flange on the spring cup and the forward end of the ball cap (my pink arrow above).

[speedytinc]

Your 24's retainer cap has a problem.When properly installed the cup gets rotated from the pin to lock down into home. You should NOT see the end of the pin in the cup. That would decrease the gap you see by aboul 3/8". We found another problem on a different car.

There appears to be excessive spring shrink in your pix. Check all the clutch linkages.
The dimension with the fingers engaged should be 13/16, not 11/16.
The gap between the retainer cup & the 4th main on your 26 looks normal.

[Chris Bamford]

John, I’m out of the garage for a while and will look into the spring cup question. Thank you.

Also I meant to say 13/16”. Good catch. I use a 13/16” flats nut with a steel rod handle as my gauge.

[Mike Silbert]

2 things jump out at me:
The 2" spring height should be when the clutch is locked up (brake lever forward)
and
If the clutch can hold you up, then a "stock" engine should not be able to make the clutch slip so that is confusing.

What is different between the 2 tests?
Floorboards, floor mat, and other stuff maybe interfering?

It might need to come apart still, I just like to know why before digging in.
Mike

[speedytinc]

John, I’m out of the garage for a while and will look into the spring cup question. Thank you.

Also I meant to say 13/16”. Good catch. I use a 13/16” flats nut with a steel rod handle as my gauge.

Regarding the 24. The pin goes in in the position you see then the cup gets rotated about 45 degrees to drop the pin into a slot in the cup bottom, thusly locking/capturing the pin in the cup. you should be able to rotate the cup to the proper position in place without removing the transmission. you will need to minimize spring tension.

(added) Grab the spring & cup & rotate CCW 45 degrees. (Looking toward the rear end) The cup will pop back into locked position.

I mentioned I mocked up some loose parts. There is very little gap (1/8') between the cup & the 4th main with the cup pin in the correct place.
That extra gap is definitely from the cup pin riding out of position on the inner cup flange.

[speedytinc]

"The clutch spring height compressed (hand lever back) is 2"+/-."

This dimension & the 13/16" dimension is with the spring NOT COMPRESSED. Brake lever FORWARD. Clutch locked up for high gear.

[Chris Bamford]

OK so: a good sleep, early out to the workshop, fresh coffee and time to mull things over in light of these discussions...

I somehow got open the wrong track with spring measurements and some general understanding of the mechanisms. This was reinforced by the sudden-onset nature of the problem and the way my '24 Speedster looks ahead of the fourth main.

In reality, the extended spring length (lever forward) calculates to 1.885", and my finger clearance is well above 13/16". So I have more adjusting to do here before pressing the panic button again.

Not sure I'll get back to the car today, but the next step is to start over, reset the fingers and double/triple check the finger clearance spring length.

Obviously.

I'm surprised nobody thought to suggest that yesterday...
_ _ _ _ _ _

BTW, I don't know how people measure spring length directly, it is awfully tight in there. Photos 1 and 2 below show my method of indirect measuring for the spring cup to the finger flange, less the length of the collar to the spring seat.

Photo 3 is my spare engine with the same next-to-zero clearance from spring cup to fourth main. Just like y'all said.

The big cup-to-fourth main clearance in my speedster remains an outstanding question. It could well be the spring cup is out of position. What threw me off was assuming the pin, when seated, is in line with the cup holes (no 45° twist required). Photo 4 shows the two spring cups I have in my used parts — both of these the holes and the pin seat are aligned. Are there other configurations for this part?

Thanks to John and Mike who took such an interest and helped me get back on the right trap. Very much appreciated. I'll post an update soon.

[speedytinc]

"I'm surprised nobody thought to suggest that yesterday..."

Resetting the fingers from a wider clearance down to the smaller 13/16 will decrease spring tension, hence less lock up pressure, hence MORE slip. That would be a step backwards for you. Likely your spring is weak. Thats the purpose for adding more clearance(widening) in the 3 fingers is to increase spring pressure.

Yes there was several variations of the spring retaining cup. The insert pin & turn 45 degree type is the later style. both your T's would have had this style. Note where the pin sits in the cups - down @ the bottom. Seeing the pin 3/8 above the bottom of the cup is the big clue. In your earlier cups, you wounld not see the whole pin, only the very top edge.
You may have guessed that by getting the spring cup into its correct position you will be decreasing its spring tension quite a bit. Slipping in high is a strong possibility.

Other than a very weak spring, misadjusted clutch linkage is a common issue. Thats why I have suggested checking several times.
You need to refer to the service manual. Adjusting by guess & by golly wont do it.

Do you have the T1 service manual & have you read the clutch section??
I have never met a T owner that had the intuition to get these adjustments correct without the manual.

Good luck & do keep us posted.