That's probably your best bet for a plan.

Is it possible your trans / engine mounts are worn and causing worse shifting under load?
I was lead to believe this is a common problem. Those are a cheap replacement, though may only partially contribute to your symptoms.

Doug

Just a follow up - I took the shifter out today to take it back to 20% reduction and I think I may have discovered PART of what was contributing to the stiffness. I think I tightened the bolt that hold the shifter in the case too tight when I took it to 33% reduction. When I was reverting I checked the movement before reattaching the shifter handle and it was a tad tight so I let up a 1/4 turn or so and it moved much more freely. I also cleaned and regreased everything like the bushing (inside and out) and when I put it back it in was like butter. It is still too "resistent" when down shifting (and upshifthing at times) for my liking but it's soooo much better. than it was. I was actually considering putting the old shifter back in. Now I feel like it was a worthy upgrade.

I am going to replace my trans mounts and my engine mounts too, just to make sure I'm covered.

Nothing personal, but Porsche folks who have a 901 or 915 gearbox should be double-clutching on downshifts. Gearbox synchros are a wear item. Blipping the throttle with the clutch depressed does nothing to the gears or shafts inside the gearbox.

As Doug suggests, worn motor or gearbox mounts can produce the same symptoms you're experiencing. Glad to hear it was a minor adjustment. Still, keep those shift assembly bushings fresh.

Sherwood

I'm in the same situation I changed the gear oil from SWEPCO to Kendell NS-MP 80/90 and made a big difference and replaced the trans and eng mounts and even better. The only problem I have is accelerating from 1st to 2nd quickly or even normally considered in any other car. She downshifts without grinding every time even around turns. My mounts looked good but I bought the sport type and made a big difference. I don't believe I need to overhaul the tranny at this point. Fine tuning is what is left and I'm happy the way she runs now anyway. I may go ahead and install the original shifter and rid the short shifter even though the difference was 10 percent not even noticeable. I recommend comply with recommendations stated on this forum before rebuilding...SAVE

Andy

Is this the same stuff, if so How many bottles do I need?
Thanks
Amazon.com: Kendall NS-MP Hypoid Gear Lubricant, 1 Qt SAE 80W-90:…

That's it.
Don't recall the exact amount 3.? quarts.
Buy 4Qts. and your good.

I'm learning driving my first porsche, an 83 SC and am very surprised that for a sports car of this caliber with it's history of racing, the shifting from 1st to 2nd is such a pain. My understanding is this is normal. You have to shift really slow. How can you do any kind of racing with this? You would get your ass beat badly if you have to pause for a couple of seconds between first and second.

Most races don't involve going from first to second very often, not even auto-x. Porsche are not drag cars, especially old ones, but damn do the new ones shift like butta.

Try a DE, and you'll learn what a 911 can do.

Chances are your '83 is 27 years old with or without previous gearbox service. Years of up and downshifting have probably worn the synchromesh mechanism (especially 2nd) to a point that it now shows issues. A gearbox in good shape should shift fine. Because the synchro design isn't the best for longevity, I'd strongly suggest learning how to double-clutch when downshifting in order to 1) shift more easily into a lower gear and 2) extend the life of the synchros.

And you have already switched gear lube to one of the suggested brands?

And you have inspected the shift linkage bushings for wear and/or replaced them?

If not, perform these operations first. Depending on the condition of the gearbox, they should make a difference.

Sherwood

Not sure what a DE is? I've already switched to Swepco 201. Bushings are next. However, from everything I've read, the symptoms I have are normal for the 915 tranny. I guess I have to learn all the subtle tricks.

I'm not into drag racing, but just for street driving I would like to be able to hang with at least a normal mustang at the stop light.

"DE"=Driver Education. You will never hang with a new Mustang from light to light..wrong place for your car. Take it to the curves and you will be more evenly matched.

Now, compared to an 83' Stang, you can walk the dog on him...that is if you can even find an 83 Mustang that is running.