Problem with 2nd Gear Grinding Options

[RMWorks]

Hi All - got a 1975 with side shift. 2nd gear is grinding primarily on downshifts and hoping to get some direction for best next steps. Here’s the backstory:

When I bought car 18 months ago the shifting was pretty vague but all the gears were there and no grinding on anything except very occasionally on downshifts into 1st while still rolling (pretty much normal for 914, right?).

Info from previous owner suggests transmission was replaced under his ownership with rebuilt unit - and if true, that means less than 1000 miles on it.

Early this summer, took the car out one day and all of a sudden 2nd gear was grinding on both upshifts and downshifts. Though it seemed more likely to grind on downshift, it would always grind on quicker upshifts as well.

Over the next couple of months I had the following done:

-transmission drained & refilled
-all main points of shift linkage checked for integrity
-replaced worn (loose and disintegrating) bushings
-checked cone screws
-found crown bushing hole in shift console was worn quite large and had developed significant play - had that fixed by welding part and sizing new opening for bushing… replaced seal/gasket and re-installed

Result is that shifting is much improved and vagueness all but gone. The car shifts quite nicely now with positive throws into each gear almost all the time.

Although I did not get a ton of road time following the repairs listed above (before putting it into winter storage), it grinds badly on downshifts into 2nd every time now (actually a little worse than before). It grinds a tiny bit on upshift into 2nd but ONLY if you shift quickly from 1st to 2nd - and only a tiny bit. If you upshift at ‘normal’ or leisurely speed from 1st to 2nd there is no problem at all. In the 20 or so miles I drove, I detected a slight grind on upshift from 2nd to 3rd once. No problem with any other gears.

Rev-matching downshift into 2nd makes no difference - still grinds. Double-clutching also makes no difference - still grinds.

I am no expert here by any means, but doesn’t the fact that it still grinds even with double-clutching mean it’s likely not a bad synchro? I also feel like the grinding on upshifts went almost completely away with the linkage improvements, so that maybe points to it not being a synchro issue..? Also thinking that the suddenness of the initial problem cropping up was more to do with linkage than a bad synchro or bad gear - which presumably would have gotten progressively bad/worse over time.

The whole shift pattern is not off to the point there’s trouble finding the gears… but could there still be some adjustment needed that would account for this 2nd gear problem?

Anything else I’m not thinking of? I consider a rebuild the last resort and based on PO’s info should not be necessary. I have heard though that you can replace 1st gear & synchro without removing the whole tranny from the car… is it likewise possible to do 2nd gear that way if necessary (wishful thinking?)?

Thanks for reading,
Dave

[windforfun]

Have you replaced the bushing in the firewall? BTDT.

[vitamin914]

Have you replaced the bushing in the firewall? BTDT.

No - I have not checked that yet - but will. There is a lot great information for me to go through in these threads. Plenty of tips and tricks to learn. Working on this for the first time will be a bit scary. My biggest fear is screwing something up and making things worse rather than better.