tranny grinds in 3rd high rpm shift

[plymouthlazer]

I would be posting this in the drivetrain forum, unfortunatly i dont have access to that page yet.

the tranny is a shepard stage 2 with maybe 300 miles on it. Mostly easy driving.
However i have tested it to see if it can handle high rpm shifts(simulating a 1/4 mile pass around 7k shift) im having an issue going into 3rd. i can shift at about 5500-6 but above that i get a slight grind.
they kept saying it was probably the clutch, and that the kevlar disc i have is heavy and keeps the input shaft spinning longer after i push the clutch, and its more work for the syncros.

my question is, if i put a lighter disc in do you think the grind will go away? or is the damage done?

[jayson427]

do you have a stock shifter? have you checked for any play in the shifter/cables or bracket itself under the center consol?

[My1GLaser]

Man, there has been quite a few tranny threads lately! There are a few things outside the tranny that determine if it goes into gear or not. Properly functioning mechanical parts that trigger a good working hydraulic system which moves a properly positioned clutch fork.

This all takes place and then you still need a good shifter lever which pushes shifter cables connected to selector levers on the tranny which need to move enough to select the gear intended. There are bushings, and adjustment nuts and possibility for worn components in the whole system. Here is how I would troubleshoot the situation.

Have somebody push the clutch all the way to the floor and measure how much the slave cyl pushrod moves. Anything around 14mm should be enough to fully disengage the clutch. If not, then you have a worn pedal assembly, misadjusted master cyl push rod, hydraulic leak, air in the line, bad master or slave cyl, etc...

Where does the clutch fork sit in the window? Did you shim the pivot ball or not? It should be in the middle or a little toward the dr side.

Where does the shifter sit in the car? In the center or is it leaned more toward one side or the other? There should be an adjustment nut on the cable and bushings in the shifter assembly.

What is the condition of the shifter bushings where the cables connect to the levers on the tranny? Are they still the stock rubber ones? Do the skateboard bearing mod.

[plymouthlazer]

ive done the brass shift cable bushings, adjusted the cables, and the symborski base mod. shifter is centered. clutch fork is just about center. no shims behind pivot ball. i adjusted the master cylinder rod out for max travel while retaining the ability to push the slave back. clutch fork moves almost all the way to end of the window(about 1/8"gap between) but my step height on my flywheel is .600 which makes me wonder if i could drive it for a few thousand miles and see the problem go away... i just really dont want to yank the tranny/pay for more repairs/different clutch right now. i have no problem driving it easy, and sheptrans told me im not doing more damage if its not grinding.

[pauleyman]

my step height on my flywheel is .600

This is the one that bothers me the most. Is that what the manufacturer suggests? I've never seen one that thin.

[plymouthlazer]

no they reccomend the factory spec of .610 its a south bend 2200pp with the kevlar street disc. didnt realize the importance of the step when i did it. i still think the NAPA machine shop should have done it to the book... i measured the step with a pair of digital calipers, but im almost ceritan i got at least a close measurment.

south bend even recommended i drive it for a while and see if it straightens itself out..

shepard however thinks the disc is too heavy and makes it harder for the syncros to slow the input shaft. they reccomended i try a lighter disc/possibly new clutch setup. but they still say the damage is probably done.

[pauleyman]

i measured the step with a pair of digital calipers, but im almost ceritan i got at least a close measurment.

almost ceritan

Not likely.

[plymouthlazer]

well theres actually 3 spots on the caliper to measure with. the inside, outside and then on the back. the back allows you to have the calipers straight up and down, and is for measuring the same side of two different height surfaces, i took measurements from all of the spots on the upper step and they were all about .600

[pauleyman]

Yes I own a set. I stand by my previous statement. I did the exact same thing as you over a decade ago. I was more than 10 thou off when I used a proper depth micl.

[plymouthlazer]

okay, ill agree with you.. were youre measurements over or under the actual, if you can remember?

[pauleyman]

I don't remember sorry. but I was a little embarassed when I argued with the machinist only to have him get a proper depth mic out and show me. From that point on I have it measured before I leave the machine shop.

[plymouthlazer]

ill try to call them back, see if they kept it on record, or at least have them look up the spec they go off of.

[DSM1G90]

Wonder if his clutch pedal ass'y is all but worn out - lateral play in the pedal...