Transmission problems: Locked out of first gear

Bmxrams80sc · 06-24-2010, 07:54 PM

Well tonight I managed to create a project for myself. I was at an intersection, put the car in first and took off across the road. As i stepped on the gas, it popped out of first with a heavy clunking noise leaving me in the way of traffic so i tried to get it back in but it wouldnt go. Ended up quickly shoving it into second. Now the car wont go into first at all. Feels like there is a wall where first used to be. Also managed to get locked out of every gear except third but then after adjusting the linkage I am back to just be stuck out of first. Any ideas? It is a 915 out of an 80 SC

thanks

wilstan · 06-24-2010, 08:26 PM

hey...same thing happened to my 85 Carrera a few months ago. Took it to my porsche mechanic and he looked at it. I told him that 2nd-5th gears felt smooth as butter, but 1st gear keeps popping out. The next day he told me that it's messed up inside and that it will need to be rebuilt. Good thing I had a spare 915 trans from a 81 SC so he swapped it out for me.

Basically, bad news for your 915 trans.

Wilstan

Walt Fricke · 06-24-2010, 08:42 PM

Might be that the 1st gear synchro retainer ring has popped off. Even if it is just engagement teeth ground down to nubbins, or a synchro or operating sleeve which is way way worn out, the answer is the same: pul the engine and tranny, open up the tranny, figure out the problem, buy expensive parts, and put back together.

Peter Zimmermann · 06-25-2010, 06:35 AM

Step 1. Raise car, remove trans fill plug, then remove trans drain plug. Post what you find stuck on the drain plug magnet.

bhoff · 06-25-2010, 10:22 AM

I had a similar problem where it would not go into reverse. The shifter coupling went bad and had to replace. Much cheaper part than anything in the transmission.

silver_911 · silver_911's Garage

Hello,

I also had this kind of problem some years ago.
It turned out to be the little plastic bushing under the shifter which has failed.
Combined with a non-perfect set-up of the whole linkage, only first gear would pop out.
So check all the gear shift linkage parts first, could save you $$$.

Good luck!

Jens

Bmxrams80sc · 06-25-2010, 01:19 PM

Thanks guys. Im most likely going to have to pull it apart. The linkage is solid, i even readjusted it. I do have a welmeister short shift which I think may have caused it or helped at least

gtc · gtc's Garage

How many miles on the car?

Walt Fricke · 06-25-2010, 04:02 PM

BMX

Don't beat yourself up over the short shift. Those might induce more synchro and other wear elsewhere (like shifting from 2 to 3 super fast), but not likely into 1st. And I doubt you failed to adjust things properly after the install. If it snicks properly into 3d and 5th, you had enough throw in that direction.

Someone recently discovered that a highly experienced race shop put the 1st/2d gear slider in backward. Those used to be symetrical (as the 3/4 is), but that stopped some while back, and everyone, amateur or pro, who works on a tranny knows about the change, its implications, etc. It is in all the references a guy would use. So you never know.

Walt

Tyson Schmidt · 06-25-2010, 04:48 PM

The dog teeth on the gear are what keep the synchro retained. The big snap ring holds the synchro and the energizers against the gear, and the synchro expands out to the inside of the dogteeeth.

If enough of the dogteeth break off, then the synchro will expand to a diameter that is too large for the slider to slide over, effectively blocking the engagement of the slider over the dogteeth, and preventing you from engaging that gear.

I'm guessing you broke off enough dogteeeth for this to happen.