TKO 600 Shifting-Had Enough Finally

[bwcobra15]

Originally Posted by PaulProe

Bobby,
Number of things:

1) are you getting full stroke with the longer pedal. I suspect it is bottoming out before you move the mastercylinder puck to its limit

2) What size is your slave cylinder? Using a .70 diameter mastercylinder for a clutch is extremely rare. You probably aren't pushing enough fluid

3) Most pressure plates require 1/2" movement at the throwout bearing. With the Ford clutch lever, that translates to about 7/8"-1" at the end of the lever, where the slave cylinder attaches - meaning the slave cylinder has to move that same distance. If your slave is any bigger than the master cylinder diameter, you will have issues.

The Wilwood slave is 7/8" bore. To move it 1", you need .6 cubic inches of fluid. The Wilwood masters used on Hurricanes have 1.25" of stroke. To get that much fluid, you need the 13/16" bore and it needs to move full stroke. It would be better with a 7/8" bore but Wilwood doesn't make one in that style.

With less than full movement, you reach a point the clutch releases but doesn't let the disc free wheel. Two issues - the transmission won't shift right and the clutch will wear quicker.

Remember in school - why do I need this math, I'll never use it

Very good info, Paul -- reminder: I have the Tilton hydraulic TOB, so no slave cylinder or clutch lever arm I"ll confirm which M/C I have tomorrow night when i get back home.

[kyleb]

Originally Posted by bwcobra15

Very good info, Paul -- reminder: I have the Tilton hydraulic TOB, so no slave cylinder or clutch lever arm I"ll confirm which M/C I have tomorrow night when i get back home.

The easy way to check disengagement is to jack the rear of the car, whilst in gear get another person to try turning the rear wheel whilst you slowly engage the clutch pedal.
When the wheel starts to free up then measure the distance between the pedal at that point and the pedal stop or when it bottoms on the firewall or carpet etc.
Should be around 1/2” from memory.

[bwcobra15]

Originally Posted by bwcobra15

Very good info, Paul -- reminder: I have the Tilton hydraulic TOB, so no slave cylinder or clutch lever arm I"ll confirm which M/C I have tomorrow night when i get back home.

Paul, I finally got under the cobra to check the MC size. Wilwood Compact Remote Reservoir Master Cylinder .750" bore:

https://www.wilwood.com/mastercylind...temno=260-6089

The other sizes available are .700 and .625 bore. So can I go down to move more fluid to the Tilton HTOB.

I inspected the HTOB and didnt see any leakage. I does look very close to the clutch forks, although I could rotate the bearing by hand. I know the forks will move closer to the TOB as the clutch disk wears thinner, but I don't think its a problem. I certainly don't have any slippage.

This is Saturday I will get the wife to depress the clutch so I can attempt to measure the movement distance of the HTOB.

Lastly, ironically, I drove it 200 miles last weekend and didn't have any problem shifting into first. Most of it was highway driving, but still didn't have a problem when I stopped. Its very erratic, this behavior.

[PaulProe]

Originally Posted by bwcobra15

. . . other sizes available are .700 and .625 bore. So can I go down to move more fluid to the Tilton HTOB.

Bobby
Going down is going the wrong direction. The smaller puck will move LESS fluid with the same amount of movement.

According to the Tilton installation page (https://tiltonracing.com/wp-content/...ies-HRB-V2.pdf) According to their page, 3/4" would work if you get about 1.3" of cylinder movement. Which I suspect you are not, especially since you lengthened the pedal. You probably should be looking at a 13/16" cylinder and figuring out how to modify your pedal lengths and stops so you are getting 1-1/4" of cylinder puck movement.

Paul

[bwcobra15]

Originally Posted by PaulProe

Bobby
Going down is going the wrong direction. The smaller puck will move LESS fluid with the same amount of movement.

According to the Tilton installation page (https://tiltonracing.com/wp-content/...ies-HRB-V2.pdf) According to their page, 3/4" would work if you get about 1.3" of cylinder movement. Which I suspect you are not, especially since you lengthened the pedal. You probably should be looking at a 13/16" cylinder and figuring out how to modify your pedal lengths and stops so you are getting 1-1/4" of cylinder puck movement.

Paul

Paul,

This weekend I was able to get the wife to work the pedal while I attempted to get hands, tape measure and iPhone all up in there while laying on the driveway for some rough measurements ...

at rest it shows about 1-3/4", and with the pedal fully depressed it shows 2-3/8" - for a total movement of about 5/8" (0.625").

The thing is: when I am driving from a stop, if I have the clutch FULLY pressed in, (and i'm guessing by "feel") when i slowly release, the pedal probably moves two-thirds of the full range before the clutch begins to engage and the car starts to move. So it seems to me the clutch is fully releasing.

AND - I dont think there is a larger Wilwood M/C than .750 in the style I'm using. Actually I found another model that is similar, in 13/16", but with a shorter stroke (1.25" vs. 1.40")
https://www.wilwood.com/mastercylind...emno=260-15092

Anyway, i'm leaving in 33 hours for San Marcos - 252 miles each way - with hundreds of hill country miles in between. Hope it behaves !

[Gaz64]

Bob,

Looking at your pics, if the 2nd is 2-3/8, the 1st is closer to 1-7/8 at best, possibly 1-15/16, which then gives 7/16 to 1/2 inch.

Gary

[bwcobra15]

Originally Posted by Gaz64

Bob,

Looking at your pics, if the 2nd is 2-3/8, the 1st is closer to 1-7/8 at best, possibly 1-15/16, which then gives 7/16 to 1/2 inch.

Gary

Gary, Ah good eye - yep, i misread the first pic. its 1-7/8. Would make for total movement of 1/2" :/

[Michael C Henry]

My car was an old running car back when I bought it. It had the Tilton 7/8"ID clutch master cylinder. Little or no free travel and just barely enough clutch release. I missed the adjustment and the throw-out bearing seized and killed the clutch fingers. I bought two new Tilton master cylinder kits in 15/16" and 1" IDs. The 15/16" Tilton clutch master cylinder gave more free travel and full release. Then I had a problem that got away from me , turned out the clutch slave cylinder was going bad and no returning to absolute rest That was no problem once I went to the local brake and clutch store. new OEM style slave cylinder off the shelf. I had already changed in the 1' Tilton master cylinder, lots of free travel and lots of clutch release, but the trade off is you gained volume and gave up leverage, I need to wear shoes to operate the clutch pedal. It has been years now since any clutch transmission issues. Now wearing the correct shoes when out driving is the concern.

[PaulProe]

Originally Posted by bwcobra15

. . .at rest it shows about 1-3/4", and with the pedal fully depressed it shows 2-3/8" - for a total movement of about 5/8" (0.625"). . .

Bobby
Look at your initial reading again. I am seeing 1-15/16" for a total throw of a little less than 1/2"

That is a little shorter than what you'd like and if you get a little sloppy and don't push the pedal all the way down (Don't ask how I know about this) then the stroke gets to be a touch too little, the disk still spins, the gears grind or shift hard.

Having just a touch more won't hurt anything and will make it a little more user friendly.

I still think your issue is in the stroke of the master cylinder. Bet you're not getting as much throw as you think you are. Back the clevis off a little on the master cylinder pushrod - which will raise the pedal slightly and give it a try.

Say Hi to the Hurricane guys

Paul