Notchy 915...why?

[alexandervdr]

I know about the idiosyncrasies of the 915 gearbox, and read a lot of the technical stuff. Still trying to understand causes and effects.
My 1986 915 is pretty good, no grinding, smooth shifting. The only precaution I take is to double clutch when downshifting from 3rd to 2nd. I assume syncros are less than perfect.
Still, I sometimes feel that shifting is kind of notchy meaning it takes a bit more than 'normal' force to get into gear. My question: what parts in the gearbox are causing this notchy feel?

[Jdub]

As you point out it is German so naturally "precise" in feel.

However, you must think about all the parts from your hand to the transmission, and again from your foot to the clutch. So is the Bowden cable in good shape, is the horseshoe spring assist clean and lightly lubed, and is the adjustment correct? Is the shift coupler in good shape, and all rubber shift parts from the coupler up to the underside of the shift lever also free of wear and deterioration?

Very importantly, is the shift fork bolted to the transmission bottom plate firmly tightened? Next time you drain your trans oil grab a fresh gasket and pull this off to inspect, clean, and Loctite back together. This is a hidden item that can really return benefits.

Lots to think about here, but the great thing is all of these fixes / maintenance tasks are relatively inexpensive and result in a real difference in feel and driving. Plenty about this doing a search and smarter minds than mine will reply to your thread. Good luck!

[john walker's workshop]

Short shifters require more effort than normal ones.

[pmax]

What notchiness ? It’s the direct feedback from moving the lever connected to a sliding ring which forces tinny teeth to mesh up and clicking all those pieces of jewelry, i meant brake band, blocks into place.

[walt]

What gear lube you running?

[Bill Douglas]

Yep, gear lube such as Swepco, new engine and transmission mounts (I used "Sports") and new coupler bushings can make a huge amount of difference. Particularly the Swepco.

[alexandervdr]

thanks for your feedback, my question concerns the internals of the gearbox. Not the oil, bushings, or mechanical links which indeed play a major role in this too ( FYI: I have Swepco and new coupler bushings). Just trying to understand (in general) what INTERNAL parts can cause notchiness. Example: is it the synchro that is having trouble sliding over the dog teeth? or is there more?

[Bill Douglas]

Do some searching on brake bands for the 915. The other guys know more than me so can probably give a more detailed explanation.

But I understand they slow down or speed up the next gear then the dog teeth lock it in. As you can imagine if it hasn't speed up or slowed down enough the dog teeth give that gear grinding noise.

[alexandervdr]

Originally Posted by Bill Douglas

Do some searching on brake bands for the 915. The other guys know more than me so can probably give a more detailed explanation.

But I understand they slow down or speed up the next gear then the dog teeth lock it in. As you can imagine if it hasn't speed up or slowed down enough the dog teeth give that gear grinding noise.

thanks, but there is no grinding noise whatsoever. It's just like sometimes I have to pull just a bit harder to get it in gear.

[PorterF]

I feel the same way about my '86. My '82 shifts very smoothly and my '86 feels like it's notchy or like it catches before going into gear. From what I can remember the '86 has something like a 10% shorter shift than the prior years.

I put in a new clutch cable, kendall fluid and adjusted the linkage. The bushings had already been done. Interesting to hear about the shift fork. I was planning on doing the motor mounts next, doing those did help on my '82. I also went with the sport/cabrio motor mounts.

Also Jonny042 has some high praise of switching to Motul Motulgear lube in his 915. There is info about this on the 'All Steel Classic Remastered' thread and the 'Dog Box Conversion' thread.

[creaturecat]

the motul certainly works well in my 915.

[Mahler9th]

"What something is worth depends on what you compare it to."

- Ashleigh Brilliant

The internet has created opportunities for a lot of bad information to be shared, including information about 915 transmissions.

I have even seen folks claim that "notchiness" and/or "shift speed" can be influenced by choices of gear oil.

Folks can decide for themselves what to believe, of course.

In my experience with 915s, the "feel" of any given 915 transmission can be very subjective. I have driven dozens by now.

I think there may be optimal opportunities to work with local resources with decades of experience to ensure that parts and adjustments are "tip top."

Then drive some others' cars to gauge how one feels about their own.

Internet cyberspace may not be an ideal venue for deciding whether shifting "feel" improvement opportunities exist with one's 915.

[Mahler9th]

By the way, I do my own transmission work except for R&P set up. There are some excellent resources out there like the famous wiki and several threads on these forums. But none of them can communicate subjective "feel."

I have been blessed to learn from folks like Matt Monson, Paul Guard, Hayden Burvill (WEVO), Jerry Woods (JWE), and of course Mat Lorance. And a few others.

[Marc Bixen]

This series will show you the inner workings:

Porsche Wiki

[RetroSC]

Everyone talking fluid and such.. but as JW said above, do you have a factory short shift kit on it? So many do at this point, and it makes a huge difference in the notchy/stiff shift department. Some like it, some don't, many don't know the difference.

[Bill Douglas]

Just to contribute to the pile of information...

My SC's 915 shifts beautifully well. But I thought I'd swap the Swepco for some new Swepco. Preventative maintenance etc. Now it is hard (harder) to get into gears. Particularly 2nd to 1st when it's cold. It always glided into 1st. It shifts fine once it's really warmed up. Quite odd. And the same viscosity of oil.

I'm wondering if my oil came from Swepco's Chinese factory

[Flat6pac]

You’ll have to pull the complete console out of the way
Picture is under the rear of the shifter the defective is the 6 mm bolts.
I couldn’t select but 4 but now all will be available
Bruce

[alexandervdr]

Originally Posted by Marc Bixen

This series will show you the inner workings:

Porsche Wiki

I have download it earlier, and had it printed and binded by a print shop in high quality so it feels like a book. Great set of info!

[911pcars]

Originally Posted by alexandervdr

thanks, but there is no grinding noise whatsoever. It's just like sometimes I have to pull just a bit harder to get it in gear.

If shifting seems more difficult in 1st and/or 2nd gears, it could be the synchro mechanisms for those gear positions are worn. These two gear positions are most often used as well as having the most gear reduction difference than the upper gears (3,4,5).

If so, it could be time for a gearbox rebuild. Short of that, I'd try a different gear lube and see if that makes a difference; in some cases, it can. Also cheaper than a rebuild.

I'd also learn how to double clutch. It reduces the need for synchros to match gear speeds, and if done correctly, won't create further synchro wear nor upset the chassis when downshifting at speed.

Sherwood

[alexandervdr]

Originally Posted by 911pcars

If shifting seems more difficult in 1st and/or 2nd gears, it could be the synchro mechanisms for those gear positions are worn. These two gear positions are most often used as well as having the most gear reduction difference than the upper gears (3,4,5).

If so, it could be time for a gearbox rebuild. Short of that, I'd try a different gear lube and see if that makes a difference; in some cases, it can. Also cheaper than a rebuild.

I'd also learn how to double clutch. It reduces the need for synchros to match gear speeds, and if done correctly, won't create further synchro wear nor upset the chassis when downshifting at speed.

Sherwood

tnx, and I indeed did learn how to double clutch when going form 3rd to 2nd such that I now do it even in my 64 Corvette C2 where it's not needed at all ;-) Still, it's a bit of an insult to what a Porsche is meant to be and the reputation it propagates: a beautiful piece of engineering where shifting should at least equal the one of a toyota corolla (even a Toyata from 86 like my 3.2 Targa)