Cam and notch movement

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Topic author
Bernd
Posts: 21
Joined: Sat Jan 19, 2019 4:02 pm
First Name: Bernd
Last Name: Lorenzen
* REQUIRED* Type and Year of Model Ts owned: 1923 Touring car
Location: Hof Luecke, 24894 Twedt, Germany

Cam and notch movement

Post by Bernd » Sun Jul 24, 2022 2:15 pm

Hi,
tonight I removed the inspection cover to take a look at the transmission. As I mentioned a couple of weeks before I had the feeling that I suddenly had more pedal travel to engage low gear.
After adjusting from outside the hogs head I was again able to engage low firmly before hitting the floorboard. As the bands have kevlar lining, I was still afraid of too much drag and ruining the drum. I will try to attach a video that shows the action of cam and notch on the low pedal shaft. What do you think, is this normal?
Thank you very much,
from abroad, Bernd https://youtu.be/zFqp5YenOcc


speedytinc
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Re: Cam and notch movement

Post by speedytinc » Sun Jul 24, 2022 2:29 pm

The whole cam is moving. That should be firmly bolted to the HH. It should not be moving.
The mounting hole & bolt normally fit pretty tight. Worn or sloppy repop?
I dont see the other cam on the pedal shaft moving, but is that a C pin holding the 2 together? If so, bad news. That needs to be fastened with a solid pin peened.

I have cautioned you about over tightening your bands & the procedure for a perfect optimal adjustment.
A little more will be disastrous to your drum. I have replaced 3 low drums for a guy who thought a little more was ok 3 times.

There isnt much adjustment left on low pedal. Kevlar bands with 1 only that worn?? Why? Look that drum face over for a big nasty crack.
Last edited by speedytinc on Sun Jul 24, 2022 2:44 pm, edited 1 time in total.


John kuehn
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Re: Cam and notch movement

Post by John kuehn » Sun Jul 24, 2022 2:43 pm

Agree with speedytinc. The cam that is bolted to the transmission cover is moving!
It’s bolted tightly from the outside of the case. Move the pedal outward by loosening the nut on the pedal shaft enough so you can slip a wrench under it to tighten it up.

If you can’t get under it remove the pedal to get a socket or box end wrench on it.

That’s a big part of the issue you have.

If it’s been moving for a while the hole in the cam may be wallowed out and you might have to get another one that will fit the bolt tighter. And you may need a good bolt also.


Topic author
Bernd
Posts: 21
Joined: Sat Jan 19, 2019 4:02 pm
First Name: Bernd
Last Name: Lorenzen
* REQUIRED* Type and Year of Model Ts owned: 1923 Touring car
Location: Hof Luecke, 24894 Twedt, Germany

Re: Cam and notch movement

Post by Bernd » Sun Jul 24, 2022 5:26 pm

Thank you both, John and John.
Speedytinc, I know you explained to me how to correctly adjust the low band and I was pretty sure I did it right but when I later wanted to push the car out of the barn it felt as if the transmission was dragging in neutral. When I started the engine the whining sound was louder than I remembered, so I opened it up again and took the video.
I'm glad you could see the movement of the cam on the HH in the video. I tried to see under the cam with a dental mirror and a flashlight but there was too much in the way to really see anything. The pin you noticed seems to be the correct one. It is not a C pin. The dark spot in the middle is a drop of oil. No movement on the shaft, also the pedal side is tight.
I couldn't detect a crack on the drum. I think it's time to lift the HH.
Thanks again,
from northern Germany, Bernd


John kuehn
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Re: Cam and notch movement

Post by John kuehn » Sun Jul 24, 2022 5:42 pm

Glad you noticed the movement we were talking about! When I replaced the notch’s on my 21 transmission cover it made a noticeable difference in the low speed adjustment,

A small movement at the notch and cam turns out to be quite a bit more because of the higher angle of the pedal I think.

In other words a 1/4 “ wear movement right at the notch turns out to be close to an 1” or more movement when you push on the pedal for adjustment! And that’s why you over adjust to try to get the closer adjustment and that’s usually too tight!


Allan
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Location: Gawler, Australia

Re: Cam and notch movement

Post by Allan » Sun Jul 24, 2022 7:21 pm

Replacing the notch replaces half the wear. To complete the job the corresponding working surfaces on the pedal need building back to spec. The pedal needs to come off the shaft, the wear surfaces built up and then the faces worked back into close contact. This refinishing is key to the job. It requires repeated filing, grinding, bluing, refitting to get full and equal contact on bot ramps. When finished, there should be 1 & 1'2" of free pedal travel before the pedal ramps up. This free play is what allows the holding of neutral with your foot, with the clutch disengaged before the bands start to grab the drum.
I have just finished this task on a well worn hogs head. Free play in the pedal has come back from almost 3" to 1&11/2"

Allan from down under.

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