901 Transmission Query
 

Does anyone know why the brake band for the 1st gear syncro is configured differently than those used on 2 to 5? With the current configuration, the 1st syncro will only work properly when downshifting. If you back up, and shift into 1st before stopping, the syncro is not effective. Seems to me that if you used the same syncro brake configuration as 2 to 5, the problem would be eliminated.

Secondly, any thoughts as to why, when the transmission is hot and the car stopped, 1st gear is more difficult to engage than 2 to 5. Replacing the 1st gear syncro hub and the 1st/reverse slider with one in very good condition helped a lot, but it still seems stiffer than it should be.

Thanks..Tim

Hmm, I came to this conclusion about the synchros recently. When you install a new synchro, the gears then mesh nicely and won't grind. However, the new synchro makes the gear stiffer, which means that you will have problems shifting into first when the car is at rest. Therefore, it's a bit of a tradeoff. The design of the 901 leaves a bit to be desired...

A new synchro will make the car difficult to get into first. A worn one will make it easier, but then you will have gears grinding.

-Wayne

I ran into an interesting problem that could be related to yours. I was having a difficult time shifting into first and reverse at all times (grinding and the like). Turns out, while doing some investigative work on my 76er, I had a c-clip come off one of the reverse lockout plate pins in the shifter inside the car. The pin was cocked out of it's place and not serving its purpose. There are two pins with with c-clips on each end and some damn STIFF springs on them that guide the lockout plate. Apparently the trans was thinking I was trying to shift into mystery gear somewhere between first and the gas pedal. Anyway once I got everything back together (after cleverly compressing the spring on a screw driver while still on the shifter) and put a new c-clip on it, everything shifts like a dream. Well.... you know.....

Hope this helps,
Dave

I don't think, in my case, the linkage affects the stiff 1st gear shift, but thanks for the suggestion Dave. And Wayne, yes I agree that the new syncro rings will make a slightly stiffer shift in any gear, but my old, very worn syncro ring coupled with a worn syncro hub and 1st/reverse slider was at times nearly impossible to get into gear when hot and stopped. My new one is MUCH improved, but still slightly harder to shift in 1st then any other gear, especially when stopped. The transmission in the 79 924 seems to (at least by looking at pictures in the Haynes manual) be very similar to the 901, yet it shifts into first pretty nice. I wonder what the experience is of anyone with a 911 using the same transmission.

Early 911s using the 901 have very similar problems with shifting. The 914 is much worse, because there are more shift linkage bushings to wear out...

-Wayne