Hi. Going through a 901 box in my '75. I have a manual that spells out different clearances between the shift forks for the side and tail shift. For the tail shift the forks are supposed to be gapped to 0.080". By this I mean after the forks are set so the sliders are in the middle of their motion, the portion of the shift rod that the shift combs engage are supposed to be setup so they are 0.080" apart. The manual then goes on to say the later side shift boxes have the distance between the 1st-R rod and 2nd-3rd set at 0.08" and the gap for 4th-5th rod set to 0.120". Problem is I don't see this in the official workshop manual and all of the info and vids on a 901 box rebuild have to do with tail shifters. I actually own the Dr. Evil DVD's but when he sent them to me 10 years ago they were in some format not native to current windows, so i don't know if he addresses this or not. I've looked all over, any guidance appreciated.

@Dr Evil (may not respond, hasn't logged in since September)

@914werke might have an idea as well

I usually put a straightedge on the inner face to make sure they are all in the same plane on that surface. That helps achieve a spacing of 2-3mm for the comb to work between the rods.

Hmm. I can get the slot opening lined up no problem, that's kinda the longitudinal positions of the shift forks on the rods. But there's a spacing setting that involves the rotation of the shift forks on the rods and this is where I'm hung up.

Also,

I've been fighting a difficult to engage 1st gear since rebuilding my transmission and am suspicious of shift fork adjustment since it feels like the selector is between combs. Interesting that its fine when cold, but as soon as it warms up....


Anyway, interested to see what the conclusions of this are and I'll pull my box and check it.

The directions are for a brand new transmission. All of them are now in the neighborhood of 50 years old, and the wear has changed things.

There is a plastic jig that is used to setup the clearances for the shift rods. You can get them really close with it and the transmission will shift fine.

But I prefer to use a cutout transmission case. I put the gear stack in it and fit the side shifter console. Then I adjust the forks so the engage with the shifter comb on the side shifter console.



There is an old thread on here about it: http://www.914world.com/bbs2/index.php?showtopic=25856

I know Dr. Evil doesn't use one, but I find it easier than the plastic jig.

Hope that helps.

Clay

Yes, I am aware that there is a jig for shift fork adjustment, I machined my own on my CNC.

I think maybe there's still some confusion about what I'm pointing out. There is a difference in how the shift rods are adjusted between a tailshift box and a side shift. I just watched Dr. Evil's vids on this and he does not mention the side clearance specs that are in both the Hayne's manuals and the official workshop manual.

I'm attaching a link to a folder with with pics of the official workshop manual which has directions for the side shift. Also in this folder is the Hayne's manual page which is (unusually!) more clear and concise.

Specs/instructions here:
901 adjustment

There is supposed to be 2mm clearance between the 1st/reverse shift rod and the 2nd/3rd shift rod, and 3mm clearance between 2nd/3rd and 4th/5th.

Are people just not doing this and somehow getting away with it?

Specs/instructions here:
901 adjustment

@jarred
"Are people just not doing this and somehow getting away with it?"

Yes. For first I align the slider so that when looked at parallel to the flat plan of the face of the slider facing the transmission, the points of the teeth from the slider are just at the border of the synchro band. Never a problem with this method. Unnecessary and troublesome to try to find that 2mm gap.

I use the exact same technique for setting the 2-5 sliders. Peer from the side, and get it close with the points of the teeth without going over. This will set the slider in the center. You cant see 2nd, so have to trust that this works (it does) when set correctly indexed on 3rd.

I use the jig for rod adjustments. Have for 22ish years. Its fine. In no way are these precise transmissions and if you get approximate by sight as I described, it will be perfect. I actually have made boxes with close to zero slop, and my method described did just fine.

@PlaysWithCars
This is a common issue. Most of the new bands are Rouch-Speigel and are very firm. If you are able to engage 1st at all, then its not a fork adjustment because you are able to pull the slider far enough onto the gear to engage it. There is no try, only do.
If you also get R, then its working in the fork department.

Did you change your slider at the same time as your band? Sometimes makes worse, sometimes better. A good used band actually remedies this and makes shifting easy with two fingers.

Does reverse grind at all when shifting into it? This should not happen and indicates a dragging clutch usually due to slack cable. Shifting that worsens with heat is often due to an incorrectly adjusted clutch cable. As everything heats up and expands it lengths and your clutch drags. Lower gears, 1st in particular, start to suck to shift into.

If anyone needs me I am easy to reach directly since I get no notifications from here. Its made the site difficult to be useful as more than a library, unfortunately.

That is "The Way" in my book.
Just sacrifice a case (or maybe rent an already modified case from Clay) and the set up should be perfect!

Thank you for sharing!

I don't understand. So do you replace that side of the case with one that doesn't have a cutout after you've repaired the transmission? Why not just make a sheet metal cover & spot weld it in multiple places? I guess it'll leak if the new cover can't be sealed. How about a huge piece of shrink tubing? Yea right. Is there much fluid pressure in there? Potential DAPO suggestion here.

The case with a window is just a jig to set up the parts. You adjust then remove the stack and put the adjusted gear stack into your good case. Peter Dawe does the same at his shop.