Encountered a head scratcher!! For some reason my GM t5 will not allow me to shift through the gears with the slip yoke(27 spline) installed in the output shaft of the trans. with out the slip yoke installed,the shifter shifts through the gears perfectly fine. All this is being tested with the engine off and maybe 1qt of ATF in the trans. Shined a light down in the output shaft and everything looks ok. Easy to spin and no abnormal slop on the out out shaft. Any suggestions ?
The shafts need to turn a little for the syncros to engage and let it go into gear. Is the yoke keeping the mainshaft from turning? Have you disengaged the clutch and tried it?
With the yoke in I can manually spin the shaft with ease. I tried once with the engine running disengaged the clutch but no luck that way either
Is that yoke attached to the driveshaft and rear end? Have you tried moving the car? If the yoke is installed with the driveshaft hooked up to the rear end, rock the car back and forth while trying to shift it (with the clutch pedal pushed down) and see if it will shift between gears. If it does.... it ain't broke.
Your clutch is either not disengaging, or the input shaft is locked to the flywheel due to a too tight bushing/bearing. Much more info is needed on your part as far as the overall set up you have and what it's in.
I can manually spin the output shaft (in neutral) with my fingers and I can also spin in it by the drive shaft/slip yoke in. But once slip yoke is in, it won't shift up stairs on the shifter.
At one point I had the drive shaft installed, ready to drive but then I noticed I couldn't shift the lever into any gears nor did I want to force it. Strange part is that it shifts fine with the yoke/drive shaft removed
If you put the yoke in, in neutral and turn the engine over by hand, does the yoke turn? Someone might have to hold it. You can try the same thing but put it in first gear, slip the yoke in and turn it over by hand, can have someone push the clutch in and she how it turns.
Of course it does, thats normal. When the drive shaft is in and hooked up, the wheels don't allow the out put to turn, and a stuck clutch or seized input shaft causes it to lock up on the other end preventing easy shifting. I'd yank the transmission and inspect the input shaft, I'd be betting the input shaft pilot nub is sitting way too deep into the pilot bearing and bottoming out on the crank causing your problem. They have to be trimmed for use in a flathead, you made no mention if this modification was done. Do this and then go from there.
Perhaps the slip yoke is bottoming out inside the tail housing? Was this transmission/driveshaft/rear end combination ever a functioning setup or is it all a new build?
I jacked the rear wheels up and was capable of spinning the trans via drive shaft/slip yoke hooked. I have never had to cut off any of my input shafts for these flathead/t5 conversions in past and they've all worked fine. Of course this shift issue
Does the engine turn by hand with drive line connected, in neutral? In gear with clutch disengaged? Will it shift while turning engine over?
At this point I would just pull it. Check pilot bushing, clutch and open up the trans, something is amiss. Doesn't sound like it's going to fix itself.
Ive had a hard time turning the engine over by hand in the past because its a higher compressed built engine( I know its a flathead). Engine starts up fine while trans is in neutral and with drive line hooked up but no luck getting into gear while the engine is on. I have not tried setting it in gear, disengaging the clutch and starting it. My friend suggested putting more fluid in it (only have about a 1qt in it) and trying it again. really strange how it shifts fine without the slip yoke installed.
It could be out of oil and work if it hasn't been run without oil before, not for very long though! I don't think adding more oil is going to cure...
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