Hi. Can anyone tell me the stroke length (extension) of the clutch slave cylinder on an '86 or so F350 with a 460 engine? I am putting a '78 460 into a '77 F250 using the flywheel, pressure plate, release bearing, bellhousing, and clutch fork from an '86 F350. I am using the mechanical linkage from the '77 and I need to know the distance the outer end of the fork travels between "engaged" and "dis-engaged" so that I can calculate where to drill the hole for the pivot end of the release rod that goes between the clutch fork and the "bell crank". I need to do this so that I can duplicate the proper travel, since the hydraulic clutch fork and the mechanical ones (which won't work with the 460 bellhousing) have different lengths between their ends and their pivot points. I hope this makes sense, and I hope someone can help me out, otherwise I will just have to take a guess and drill as many holes as I can fit in that arm to give myself as good a chance as I can of getting it right. Thanks in advance to anybody who actually reads this far and tries to help!

 

the slave cylinder travels the full distance from new disc thickness to worn disc thickness which makes it self compensasting for wear.
so asking for 'engaged and disengaged travel' is not the same as total slave stroke and will not help you in making the linkage.

take a ruler to the parts store and get them to hand you a 460 application slave
I have the other application slave here but the bore size is only 1" as opposed to the 460 one that is 1.0625", the stroke of the 1" is around 2.5" (I got 2.575")

both use the same master with a 7/8" bore and a stroke of about 1.6".
I built my hydro conversion pedal to have a 1.5" stroke

I still say you are going backward in removing the hydro linkage.

 

Thanks for the info. I understand your point about the self compensating linkage, and now that I understand that, I guess my question should have been about the travel length of the outer end of the clutch fork, rather than the stroke length of the cylinder.
Once I know how far the fork needs to move, I can calculate the length of my linkage.
And as far as going with a hydro clutch goes, I think it would have been just as much trouble, if not more, to fab and install a hydraulic pedal assembly and master (if I had one) as it was to install the mechanical one, and then I would have a hydraulic one which will fail long before a mechanical one will, (I.M.O.) I already have everything installed for the mechanical set up. all I need to know is that number, and I will have it working.
Thanks again, I appreciate your time and interest.

 

when you are building the linkage just remember with a diaghram style pressure plate the clutch fork end that your linkage pushes on moves toward the back of the vehicle as it wears.
so with a new clutch disc installed the fork is as far forward as it will ever get and your wear compensation will be lengthening the linkage.

truthfully if you have a mig welder, something to cut metal (hacksaw, grinder with cutoff disc), and a hand-drill with a 1.5" hole saw the hydro linkage would be an hour or so to duplicate what I did.
I have a drycut saw and also used my portaband as an upright bandsaw to form the firewall reinforcement bracket

 

Thanks again for the added info, I didn't realize the pressure plate would get "shorter" as it wears. I will take this into consideration .

 

wait. I was backa$sward, the diaghram fingers get longer as the disc wears so the fork will travel forward as it wears.
sorry bout that

 

O.K. Thanks for the correction. I was trying to figure out how that would work.....

 

I think we can math out the slave stroke using the master's volume

pi r² x stroke
pi (.875/2)² x 1.5 = 0.90198 inches³ of displacement for a full stroke of the master

so how much will the small block slave move with that volume of fluid

pi (1/2)² x X = 0.90198 inches³
X = 0.90198 / pi * .25
X = 1.15"

the 460 slave is a tad bigger

pi (1.0625/2)² x X = 0.90198 inches³
X = 0.90198 / pi * .2822
X = 1.02"


check the math as I mighta messed up

 

Yes, the math works out the same for me, too. Sounds like I should aim for a 1" stroke, I think, just to be certain, I am going to find a 460 4spd pick-up on a sales lot or somewhere and physically measure the fork travel. If I can't find one to measure, I will use the target of 1" for my starting point. Thanks again for all the help. It is much appreciated!