Transmission Check

[grumpy56]

Hello all. Just fitted the shift cam and transmission back in my 72 GT380. I am able at this stage (shafts just resting in bottom case) to click up through the 6 gears about 1 in 3 attempts. When it goes as planned, it is slick. However, on the other tries, it gets to third or so and just will not move any further. Would that be expected without the shafts spinning? Thank you.

[Alan H]

Gears should be spinning to change properly.

[tz375]

Alan is correct, When you try to change gears with an engine that is not running, often the gear dogs will hit the dogs on a matching gear and will not engage. Just rotate or both shafts a few times, and it should slip into gear.

[grumpy56]

I am turning the driveshaft by hand as i attempt to shift gears. As stated, sometimes I get clean shifts up and down and then other times get stuck in third and cannot get it into 4th without going down to second and trying again.

[tz375]

As you turn the shaft(s), look at the gear that's moving and you should be able to see the dogs bumping into each other when it won't shift. Turn that one stuck gear slightly by hand and it should slide into gear.

If you look at the gear shafts as you click through the gears it's easy to see which gear moves and it should be possible to see the dogs engage and disengage. Each change lock one gear that's free to rotate onto one that is fixed on the shaft.

[grumpy56]

Thanks tz375. Will see if I'm able to "help" engage then to ensure everything is OK.

[jabcb]

Had a similar experience when I did this test before bolting together the GT550 cases. Mostly shifted smoothly when I slowly turned the transmission, but a few times it was fussy.

Now assembled & on the road, it shifts flawlessly.
Transmission was turning at perhaps 10 rpm when I did the test. Big difference on the road with the much higher rpms.

[grumpy56]

That's what I was hoping. It's just a bit concerning at this stage since a screw up at this point is a BIG problem. Thanks.

[grumpy56]

Still can't get it to shift as well as I'd like. Seems to go 1st to third OK and once in 4th, then to 6th and back with no problem. Other times it hangs up or snicks right through. Hopefully it is due to just not spinning fast enough so will close my eyes and continue on!!!

[tz375]

If the top case is off, look at the gears as you shift through the sequence. You should be able to see which gears move and see what is stopping any particular selection.

[grumpy56]

Will try to see why that 3rd to 4th is not consistent. Also, I think this is all I need to install before putting top case on. IS it best to install anything else, i.e. kickstart, to test it before I Yambond it? Thanks.

[grumpy56]

I can't attach a photo here. Will try to find out why.

[tz375]

file may be too large. If using a PC, download microsoft powertoys to get image resizer. That should do it.

When you shift from 3 to 4 and it baulks, did you try gently rotating one or other of 4th gear and see if it clicks into place?

[grumpy56]

Thanks tz. Yes, I did but no movement. Everything seems bound up, so not sure what I have going on.

Will try reducing the file size.

[tz375]

either the dogs are hitting each other or the sliding gear is hanging up on a step or burr in the shaft. That's more common on gears that rotate than on gears that slide, but anything is possible.

If the dogs are clashing, turning the shafts a few times won't make much difference. try turning one gear relative to the other and see if it slides into gear.