915 Rebuild

[darud35]

Hi all!

I just picked up my first 911! It's a 1975 911S. I had a great "break-in" drive from San Francisco down to Orange County. Here's a photo on the way back.



The transmission was grinding when going into first. I was able to avoid the grind by going into third, then first. It was believed to be synchro's so I pulled the trans. While pulling the transmission I noticed some badly worn bushings causing excessive slop. I now have the trans open and it doesn't seem like there's excessive wear on the synchro's but I'm not entirely sure what I'm looking for. This is my first transmission job. Here's some photos.




I also noticed what looks like porosity on the end of the main shaft.



Is it possible the worn bushings were causing the grinding or do these synchro's look bad? Any advice would be appreciated!

[Matt Monson]

The factory manual has minimum dimension that the synchro should measure. Don't have them handy but you need to measure turn with the slider selecting the opposite gear so the one you are measuring is not under compression.

[kodioneill]

The dog teeth in the photos are worn out and rounded off. The syncro's look a little shiny but it's hard to tell unless you clean the oil off everything. The experts here will tell you to replace the slider if you replace the syncro's it's a must. I just rebuilt my trans didn't take any chances I replaced 1&2 3&4 sliders, syncro's and dog teeth. The syncro's are worn if the hard coating on the outside is worn off there will be shiny spots. Some guy's will tell you just to turn them around but I wouldn't.