Technical Really hard pressure plate. Need help!

I wonder how much friction is in the bellcrank pivots?

 

Probably not the issue but back in HS a buddy converted his 6 cylinder Nova to a V8. The Nova had a 3 on the tree but the V8 was a junk yard special out of an automatic car. Everything went together just fine but the clutch peddle was hard to the point it wouldn't work. After strengthening the Z bar it still wouldn't work. So he had it towed to a shop. Car was back the next day. It helps to install a pilot bushing.

 

Pilot bushing is definitely in there haha

 

I've got full travel of the master cylinder, so I dont think that's a problem. Doesnt seem to bind or anything

 

No bell crank installed, just the slave cylinder straight to the clutch fork

 

I meant the bellcrank pivots between the pedal and the master cylinder.

Might be helpful if we could see the entire pedal and master cylinder setup, from a couple different angles

 

Have you checked the pedal ratio?

 

Not much leverage from the short top pivot.

 

Well that's a good start!

What's the pedal travel like (in inches) at full travel of the master, a) dry, b) wet, ie fully bled etc.

My guesses are a) a couple of inches or so, and b) almost nothing, as its solid. Very happy to be wrong though!

Chris

 

Pedal travels about 6" to move the master cylinder about 1 3/8"

 

you probably want closer to 6:1, than the 4.3:1 ratio you have.

Still would like to see how the whole pedal setup works...

 

Sorry, I'm trying to upload a video so it makes more sense, but it's not working.
I'm starting to rethink the clutch as the problem now as well and thinking I may just drop this whole levers, cylinders etc. U could be chasing this for weeks and now I'm leaning more toward the hydraulic throw out bearing. I know they can have there own complications but who knows where this set up is going

 

thanks for the pictures..but they dont show the pedal. I can't see if it's up all the way. It makes a difference, the pivots all need to be perpendicular when the pedal is in the middle of it's travel, or it won't work right

 

Sorry

 

There's quite some work in that installation and if looks to be nicely done and finished. However the additional pics confirm, we'll in my eyes, that the clutch pedal is way too short and thus can't provide the leverage and travel to produce the required pressure and flow. Take a look at the Kugel setups, the pedal pivot is high up at the master cylinder level. The acid test here is the pressure at the slave.

Whilst looking at the Kugel stuff do check out the ratio of the bellcrank. Looks to be 1:1 as best I can see.

Unlike some I'm happy to use a hydraulic throwout bearing but you still need the pressure from the master so the pedal arrangement will still sucker you as it is. Tough love.

Do please share the dimensions of everything between the pedal pad and the master.

Chris

 

Glad someone else spotted this too! With the latest pics I can now see 3 places where there is some loss of movement, which will all compound the situation without considering the losses at the business end. And that's without the pedal ratio issue.

Chris

 

Looks like you loose your leverage advantage with the top bellcrank. I would think it should be at least 1 to 1 or the opposite way that it is now, with the short arm to the master cylinder to gain mechanical advantage.

 

Damn it! Back to square one I guess. I'll start messing with it in a few days.

 

This^^^
That's some beautiful work on the entire system; but that top bellcrank is a major part of the problem.

 

Just throw that whole system out and install a hydraulic throwout bearing and be done with it. [McLeod make one for the A833]
It will clean up the whole mess under there [and leave more room for exhausts etc]

Some people are skeered of this new fangled technology , but they have been reliable on modern vehicles for the last 20 years.

 

NOT TRUE!
The biggest problem here is in the pedal to clutch master operation. If that was correct, I suspect the hydraulic set up he currently has at the bell may well have worked.

Add me to the list that believe the issue with the pedal linkage is at that top pivot. The rod lifting up to that top pivot can only move up until it makes contact with the other lever in that pivot, and that is not enough to push the rod into the clutch master far enough. I believe the pedal end of the top lever needs to be 2x longer pivot point hole to pedal rod hole (maybe more) then it currently is. You are probably only getting about 1/2 of the clutch master's stroke, and that is not enough to release the pressure plate. As is, about the time it starts to release the clutch, the master runs out of stroke.

There may still be issues at the bell as well, but the top bell crank problem has to be solved first.

 

That's not the point of my comment.
Start eliminating areas where people get out of their depth [usually geometry]

I would start with a hydraulic throw-out bearing [this eliminates clutch fork and slave cylinder angles and leverage]
Then proceed to the pedal assembly which looks like a geometry nightmare.



All that complicated bellcrank could be eliminated with a simple reverse mount M/C


Or simply alter the existing bellcrank and mount the M/C further up the steering column out of sight.
Use a M/C with a remote master cylinder with a long pushrod and a heim-joint at the bellcrank

 

In looking at the pics of your linkage, it seems that every extra piece makes your lever ratio worse and worse.

First pic in post #52---- the red hashes and the blue hashes added show you have the opposite ratio than needed. Would help alot if you could just flip that bellcrank or at least make a new one that was 1:1...

The Yellow hashmarks in pic one also could be moved closer together. Do you have the ability to pop another hole in that arm and move the attachment closer to the pivot?


-rick

 

The top pivot doesn't go up, it goes down, so no interferance there

 

I'm going to do something similar to that now

 

You could put the pedal back under the floor & use mechanical linkage , If I can do it in the confines of a T bucket body/ frame , I ll bet you can make it fit under your car ...

 

Get a piece of round tubing with the ID the same as the column OD
Cut it longitudinally [1/2 round channel] and weld a bracket for the M/C mount onto it.[this can be gusseted]
Seat this piece up against the steering column drop so it wont move and clamp it with 2 Mikalor clamps



here is the Mikalor clamps


Doing it this way allows for the column to drop through the firewall [non rag joint /universal joint style]
And saves welding to the column

Then alter the bell-crank as previously suggested

 

@Kerrynzl, interesting idea but did have me scratching my head at first, mounting the master to the column? Wild!

I'm not seeing that working though as the pedal itself is just too short. With the pedal arm shortened to get an appropriate pedal ratio the arm will be too short to give the inch plus to fully stroke the master. The pedal has to be lengthened which will require the mount / pivot point to be raised. We'll, that's as I see it!

Chris

 

You clock the lever [blue arrow] so it is perpendicular to the M/C pushrod.
The lever can be lengthened or shortened to the desirable ratio, so the pedal itself can remain the same length.


The clamp on bracket is just a mounting method [for columns attached to the steering box]
The M/C mounting bracket does not need to be perpendicular to the column [neither does the M/C need to be parallel to the column]

The easiest method is to clock the lever first and get the correct ratio at the same time.
Then use a string line to mimic the path of the M/C pushrod and M/C centreline. [then the M/C bolt mounting bracket mounting angle can be figured out.
once the string line has been established , you can also cut out a cardboard silhouette, and place it up there to see what is happening [this is much easier than fabricating something only to find out later it won't fit]

It doesn't need to be parallel, it can be triangular shaped.
The M/C pushrod can be lengthened and a heim joint used at the lever end.
@farmer013 will have a few leftover heims as only one is needed.

This is easy to figure out on paper, but the string line method is the most practical for those who lack trigonometry skills [math]
Try figuring this shit out on a racing car where the driver's feet, steering column, rack, pedals, balance-bar, 3 M/C's, and rocker suspension are all competing for the same real estate

 

@Kerrynzl, yep, got that, but if the actual pedal is undersize (like a scale model) with 6 or 7:1 factored in I think its unlikely the master pushrod will see enough travel, 1.12" approx, to work properly, as the scale model meets the full size world.

Chris