MTFCA Forum

The clutch pedal on my 26 has excessive wear on the cam. I'm building up the surface with weld and then filing it to shape.

Does anyone know what the ramp angle should be on these cams?

The photos are as found when removed from the hogshead.

I’m thinking the cam angle on the clutch pedal would the same angle that’s on the notch that’s attached to the transmission cover. Only opposite.
The cam on the pedal mates up against the notch angle when it’s compressed together.

In other words the correct angle for the pedal cam would the angle that’s on the notch assuming both cams are not worn.
I think I would install a new notch while you have the cover off if your wanting to get good clutch action.

Others might have a different idea about the angle.

There was a discussion related to mating the cam's to the pedal counterpart. I am just posting picture for you to reference. The cams appear to be spiraled not just a simple angle

Yes your right about the spiraled angles. The spiral helps the pedal sort of ‘roll off’ the stationary cam on the transmission cover. If it was flat on flat it wouldn’t have the the roll off effect.

Odds are pretty good that it’s not really worn. The clutch cams are supposed to have additional play. That’s what allows you to push the pedal partially in to actuate the clutch without engaging low band. The cams are also internal and run in a constant oil bath. Usually they aren’t too worn.

If you get rid of the play you will never have neutral at the pedal, only with the hand brake lever...

It's a right hand drive hogshead, hence the greater wear, since the cam is on the outside. This pic of mine shows the cam arrangement.

When I do this job I start with a new bolt on ramp. The pedal should be removed from the shaft to have its ramps built up with weld. Then the fitting begins! Some bearing blue is your best friend. Once the welds have been roughed back, the pedal is fitted to the shaft, with no pin at this stage. fit the new ramp to the hogshead and blue its surfaces. Slide the pedal into place and work it on the ramp. The blue will show the high spots that need dressing down. The ramp is a spiral, and it will take considerable time to get the new welded surface mated with the ramp surface. Each time you have to work on the pedal ramps the pedal has to come off the shaft. I cheat a bit here, leaving a used and ever so lightly undersized shaft in place in the hogshead as a pilot for the pedal.
Once you have the two faces mated to one another, you still need to check that you have play in the pedal that allows you to hold a neutral with your foot. There should be approximately 1.5" of free pedal travel before it starts ramping. On my first attempt at this rebuild, in ignorance, I took out all the free play and had no neutral.

Hope this helps.
Allan from down under.

Thanks guys, that spiral will make it a bit more complicated to get right.

Here is a clearer photo showing the cam wear. The hole for the linkage is also a bit worn so I’ll have to deal with that as well.

She’s had a hard life.

The clevis hole is an easy fix. Clean it back to bare metal and bronze the hole up completely. Then re-drill a standard size hole through the bronze. Chances are you will then have a bronze bush in the hole.

Allan from down under.

If possible it might help if you had a better clutch pedal but that’s not something that can always be found.
Just thinking about it but if the suppliers can make the brake and reverse notches the clutch pedal pedal cam can be made also. They could be made just long enough to be welded on the existing pedal. Cut off the old worn end and then weld on the new cam.
I’ve been to a few swap meets where folks have been looking for replacement pedals and sometimes you can find them.

I am not sure this will add any value, but here goes.

My father and I (60 and 88 Yr old) have 3 T between us. All are in the 20's. He retired from large consumer products company as mechanical manager in bar soap manufacturing and engineering. I have a mechanical engineering degree, however never used it. After graduating in the 80's, I went right into IT support for CAD/CAM, programmer, trainer, support. I currently work for an aerospace engineering company.

I have access to a CAD modeling program (Autodesk Fusion 360). I have decided to model T parts that are not being reproduced as a retirement gig. I have access to a metal 3D printer (that we use for Aerospace parts). The idea is to "print" tough to get parts like the pedals. I am just at the beginning of the journey, can't predict where it will end up.

The first parts I decided to model are associated with the hogs head. So I started with the Cam Supports (or whatever they are called).


Since I do not have original drawings, I had to use my trusty machinist scale (I worked in machine shop in high school) So my first disclaimer is that the dimensions may not be accurate.

But in building the model of the support cam, I discovered the angles of the cam, at least I believe I did. Please see drawing. The process to generate the cam is called "lofting". It is a process used in ship building and aerospace.
https://en.wikipedia.org/wiki/Lofting#: ... odworking.
It is not as complicated as it sounds, just a simple surface between two lines generated around the center of the hole.


If anyone has original dimensions, I would be willing to modify the model to make it accurate. Then I start modeling on the pedals with an eye on getting them 3D printed.

Why not try and get the original drawing from the Henry Ford?

Ted, thanks for the drawing. That is very helpful. The 30° angle in your drawing makes sense. Hopefully I can replicate it freehand.

What kind of metal 3d printer do you have access to? Those are high dollar items!

The bolt on ramps/pedal supports presently available from the vendors have proved satisfactory when I have had cause to use them. It is unworn pedals which are scarce. On RHD cars this is the clutch/first gear pedal. On LHD cars I presume it is the brake pedal that cops most wear. If those were made it would be a big help.

Allan from down under.

John, A GE Additive Concept Laser DMLM machine. We also have a "plastic" printer. Since the world has gone to additive, we are trying to stay out front on changing our design processes to best suite additive.

Dan, I always wondered how to request drawings from the HF. Is there a link or a post that directs me to the correct place?

Ted

Here is the mail order form, right now due to pandemic, there is a delay in receipt as only a few staff are there. Note, you must use the "Factory Number" for parts, not the normal part number in Parts and Price books. The Fac .No. is shown in the far right columns in Price List of Parts.


Just Google 'The Henry Ford part drawings', and the home page of the details is there, below is the link to the mail order form.


https://www.thehenryford.org/documents/ ... f?sfvrsn=6

Dan,

Thanks for the two pieces of information. How to find the factory number was the piece that I was missing. I see that the Model Aers have an online search index, I wonder what it would take to get the T index online or even better, the DWG online to purchase? I think I will broach that with the HF and see if I can get some interest.

Ted