f-1 trans help needed

this one has me stumped. customer complaint was gears grinding. wont downshift 3rd-2nd. put in new clutch disk and p/p. went thru trans. eliminated mainshaft endplay. 2nd gear endplay within spec and no wobble from the bushing. polished the small burrs off the sycro sleeve teeth. new blockers,springs and clips bearings seals etc. had the trans out 2x and i cant find anything wrong with it. the clutch seems to be engaging and releasing ok and it shifts up ok. what the hell can the problem be? flywheel? thats the only thing i havent touched...advice please?

 

Is he trying to downshift as quickly as he upshifts? If so that may be the problem. The pressure on the syncros is much higher downdshifting and a slower shift is usually required to keep grinding to a minimum.

Frank

 

I was thinking the same thing, maybe its the driver and not the trans.
Have you drove it?

 

its a sideshift box...i test drove it before and after i had it apart. same problem each time if i slow to about 15 mph i can sneak into 2nd but from any speed above that its as if im trying to shift without clutching

 

Driver doesn't know how to shift an antique truck trans !
Tell him to change gears slowly !
It's not a new little car with a 5 speed !

You could take him out in his truck as you drive and teach him how to shift an antique truck trans and that will take care of the problem !

 

These transmissions (I assume this is the early Ford sort) suffer from stretching of the case...when you work on endplay at the actual ends and kill off the endplay there, they can still be a bit open in the middle, by which I mean forward shaft and output shaft having endplay where they insert. Since this heap of iron is coming apart again...squeeze the upper shaftage together endwise ( a lathe is ideal) and measure between the end bearing snap rings, then measure the equivalent on the case. You will likely find case is too long. Some space can be removed by milling rear of case, if not possible consider seeing how far you can move stuff with extra slingers as spacers. If this central gap is present, it subtracts right out of 2nd gear synchro engagement, quite possibly rendering the braking surface inop as well as cutting synchro tooth engagement way down. This info stolen direct from a 1960 article about blueprinting Ford transmissions to survive dragster use...I have never done this, all my Ford trans work has been done in blissful ignorance of the many problems caused by several different endplays in the transmission...it was not in the Ford trans manual, and I didn't think enough...

 

Also...check out Rumbleseat's postings on failures of repro brass rings on Fordbarn. Some are just no good.

 

i will check that the way you decribe bruce...as a side note, i found the snaprings on the new bearings too thin, gaskets too thick and wear in the groove of the front and rear bearing retainers causing a LOT of end play that i eliminated but if the case is too long, there still may be too much gap at the sycro...