bran3b

Long story short, my brother's '79 needed a transmission, the original one is definately unusable, so I put a spare that I had in it. He was coming to town for the holiday weekend and I wanted him to drive his car while he was here, so I installed the transmission without a deep dive inspection, and went off of what I could see from the top, it looked good.

So now the transmission is in, clutch is adjusted, linkage is good, but it just won't go into 4th, all other gears feel perfect. With the engine running and the car moving, it feels like the gear teeth are hitting, but there is no grinding, just a bouncing feel ing through the shifter.

My plan now is to pull the transmission back out and dig into it, any pointers on where to start looking? I don't feel like it could be synchros since there is no grinding and it won't go into gear with the engine off. I thought that the gear could be out of alignment, but figured that this would cause trouble in other gears.

Ducman82

how did you set the shifter linkage?

bran3b

I started with it as close as I could get it to centered, then with it lose I went side to side with the shifter to get it centered. Once I was comfortable with side to side, I tightened the collar and put the transmission into 2nd, then loosened the collar. Once lose I was able to slied the shifter a bit forward. Then I locked it in place and went through the gears. When I couldn't get into fourth I re-ajusted more to the left and back with no change in the feel into the other gears but also not able to get into 4th.

The Deputy

Does the shifter go forward the right distance to engage 4th, or does it stop short...like it can't go the distance needed? Does the shifter go as far in 4th as it does in 2nd?

I'd assume if it were an issue with the shifter fork or synchronizing collar...in the trans...it wouldn't go into 5th, too.

I wouldn't go crazy and pull it out until some others check in, holiday weekend doesn't help any. Worse case scenario, I could go pop the cover off my extra 5 speed and we could compare linkages. I need to have a looksee in there anyway, so let me know.

Brian.

bran3b

Brian,

The shifter seems to stop about half way, definately shorter than the travel into 2nd. The feel isn't solid, like it is hitting anything up toward the shifter, it feels like there is something in the way farther back.

I'm not pulling it tonight, taking time out of the garage to relax, hoping that someone has seen this before, or hoping that in the morning I will have a fresh outlook and can see what I am missing. I do still have the old transmission, so maybe I will pop the cover and look in there as well.

Thank you,

Ducman82

go under the car and disconnect the trans shift coupler clamp. then get the trans in to forth from down there by using the coupler. then have some one hold the shifter forward and right, "where 4th should be" then re tighten the linkage.

bran3b

Genius! I wouldn't have thought of that. I'll do that in the morning. If that works, it will save me hours of work. I'll report back after I follow those steps.

Thanks a ton!

The Deputy

This^^^^

Was thinking the same thing last night while laying in bed. Disconnect, see if the trans goes into 4th by hand (that at least rules out pulling the trans) and reconnect as mentioned above. It sounded like a linkage problem from the get-go...hopefully this does the trick.

Brian.

bran3b

It looks like it is in the box. I tried to eliminate the linkage and still can't get it into gear, I was able to get it into the others though. Without anything to brace against it was tough to get into 2nd but it did go in. I'll pull the transmission next week and see what I can find in there.

James Bailey

most likely an expanded syncro ring jammed up on the stop/ramp....caused by a very aggressive attempt to shift. It totally blocks the engagement so no grinding just feels like a complete lock out of that gear alone. Read more in the 911 section all the early boxes used Porsche Syncros and many "racers" manage to lose a gear.....some more than others

bran3b

James,

Your description sounds pretty accurate. Is there a way to fix it without completely tearing the transmission apart?

Thank you,

mark kibort

sounds like a shift fork alignment issue. will it go into 5th. 1st and reverse are one..... 2nd and 3rd are another and 4-5 are yet another shift fork. if the problem is only 4th, it still can be shift fork related, but it would probably more likely if you cant get it into 5th too. Also, the 2-3rd gear fork might not be allowing engagement, so it could be the culprit too, even though its working fine. (3rd not being released, so 4th cant be engaged)

bran3b

It will go into 5th. I will pull this transmission and put it next to the old one which is in bad shape but it does go into all gears. Hopefully comparing the two will point out the issue. I'll post as many pictures as I can.

I'll pull the transmission when I can, although that might not be until the 11th. At least this will be a good learning experience.

mark kibort

still can be a shifter fork adjustment. it cant change shift bar rails and go the opposite direction to get it into 4th. however, if 5th is ok maybe that direction is fine. however, if the syncrhro ring is damaged as jim suggested, it just cant engage and is jaming up. that certainly would be a problem that would require surgery. hoping its the shift fork adjustment . good luck!

bran3b

It looks like there is something wrong with 4th gear synchro. I'll try to get some pictures but basically the ring looks lose when I compare it to the other 2 transmissions that I have to compare it to. It looks like someone already went through the transmission but did a failry sloppy job of it. I'll pull it apart and refresh it. In th emeantime I put another transmission in the car and confirmed that it will now go into all gears. I'll finish putting the car back to gether and see how it does.

The shift fork does seem to be in good shape.