Adjusting 1st/2nd shift fork on 915

[scottc]

I'm reassembling my mag case 915 after new synchros and seals. I carefully marked the position of the 1-2 shift fork on the rod with a sharp, hard scribe as described in Haynes. How close must one get the fork's position when reassembling? I can't find any references to allowed tolerance. I do not have access to the factory jig so am hoping that carefully putting it back where it was when it was shifting well is good enough...but I don't want to have to pull it out just to readjust the fork.

Does anyone one have info on this or any first hand experience on this adjusment without a jig?

Thanks,
Scott

[ChrisBennet]

If you put the center case section on you can look through the hole and see if the forks have the right gap between them. I just eyeball it but the factory spec is 2-3mm. They must not touch.
If you do another 915 rebuild be aware that loosening the shift fork (and thus losing it's alignment) is unnecessary.
-Chris

[scottc]

Chris;

Thanks for the prompt repy. I only loosend the 1-2 brass fork from the rod but I now realize that I didn't even need to do that.
I am not sure what you are refering to when you say that there should be 2-3mm "between them"?? I mean the axial position of the brass shift fork on the 1-2 rod. Is that what you are refering to? With my little scribed mark on the rod I feel I can locate the the brass fork back into position +/- .020" or so.
But since I have not seen one of the factory alignment jigs I am not sure how acurately it aligns the forks.

Sorry if I am missing something obvious here.

Thanks,
Scott

[ChrisBennet]

You want the openings of the little "forks" that the selector uses to be flush (vertical blue lines) and you want the gap
between them to be .2-.3mm (horizontal red lines.


All the jig does is hold the end of the shafts in the same position they would be if you had
assembled the case. Here's a picture of the jig on the right end of the shafts:


If you slide the center case section on you can just look through the opening at the bottom of
the transmission to check the gap. The angle will probably be wrong for viewing the gap directly but
you can just use a homemade feeler gage (piece of cardboard) if you need to.


-Chris

[john walker's workshop]

many transmissions have been apart before, so the shift fork position is not necessarily optimum. when the shafts are bolted down with their thrust plates to the diff housing, temporarily install the 5th gear inner race, thrust washer under it, and the 5th/reverse hub, and snug down the pinion nut so all the items on the pinion shaft are properly pulled together. then check that both shift sleeves are centered between the gears on either side of them. easy to see by comparing the exposed ends of the three arm hub that the shift sleeve slides on. you want an equal amount showing on each side of the sleeve. then of course the rods are aligned to each other as per the above pic.

[scottc]

Chris and John;
Thanks so much for your advice. It went together slick as you like using your recommendations.

Scott