915 tranny grinds neutral to 1st???

[DarrylD]

So I'm kind of religious about putting my 911 in neutral and letting out the clutch when I'm sitting at a traffic light. However when I put the clutch in and shift it into 1st it usually grinds a little bit.

Should I be concerned about this?

[SCOTITUDE]

Mine did same thing for years until it finally went completely at Summit Point DE pulling out of the pits. The first gear synchro was shot. I had the tranny "freshened" but not a total rebuild. Cost $600.

[Zeke]

Try this, after pushing in the clutch, just *touch" second momentarily with the gear lever and then shove it up into 1st. It works for putting the tranny in reverse right after clutching, that I know for sure.

[Bobboloo]

If left unattended the car will eventually start popping out of 1st gear because the gear teeth will round off.

Is your clutch adjusted properly. i.e Does it fully disengage when you step on the clutch pedal? If not this could be your source of grinding. If it is adjusted properly then your 1st gear sychro is probably going.

[911pcars]

...or check the clutch pedal free play. The clutch may not be completely disengaging the engine and trans. Does it grind into reverse as well?

Sherwood

[DinFtown]

If that's the only problem you are having with your 915, consider yourself lucky...... wana trade???

[astark]

Darryl--

I had the same problem and thought a rebuild was necessary. Not so! I replaced the bushings in the shifter, and replaced the shift coupler bushing with a WEVO. After careful adjusting (I'm still tweaking the shift coupler bushing adjustment) my shifting is MUCH improved. I can now get into 1st while rolling no problem.

I think the issue centers on the amount of time after depressing the clutch before attempting to engage 1st. I still give the 915 a few seconds after depressing the clutch before attempting 1st gear. If I'm the first car at the light, I try to depress the clutch and wait (say the word "checkbook") before attempting 1st. If I can see the traffic light clearly, I start this proceedure when the amber light is active for the perpendicular traffic. This gives me time to engage 1st easily. If I am in line at the light, no problem. I always have time before the cars in front of me start to move.

If I have to shift into 1st fast, I use the technique recommended by Zeke, ie depress clutch, bump 2nd, engage 1st--no problem.

Hope this helps,
Alan

[Ray B]

Ditto what Alan said. A local mech told me it may have to do with the pilot bearing... Just curious, do you blip the throttle just prior shifting into first? Just give it a second or two at idle rpm before shifting.

[Grady Clay]

All of the above are correct.

It could be worn syncro.
It could be dragging clutch (from adjustment, oil, or simply polished.
It can be from rushing to put it in first.
More?

One thing you need to consider is that 1st gear syncro is asymmetrical – the syncro is designed to have greatest effect on down-shift from a higher gear. Porsche accomplishes this at the expense of the synchronizing effect in the “up-shift” from neutral. Assuming everything else is correct; this is the reason for the “pause” when going from neutral to 1st.

This is also true on the 901, 904, 906, 911, 914, and 930 transmissions.

I like to put it in 1st just prior to stopping and hold my foot on the clutch.

Best,
Grady

[porschenut]

Originally posted by Grady Clay
I like to put it in 1st just prior to stopping and hold my foot on the clutch.

Good. That's what I do too. Engaging first gear is easiest when the car is just barely rolling.

[Zeke]

Originally posted by Grady Clay
All of the above are correct.

It could be worn syncro.
It could be dragging clutch (from adjustment, oil, or simply polished.
It can be from rushing to put it in first.
More?

One thing you need to consider is that 1st gear syncro is asymmetrical – the syncro is designed to have greatest effect on down-shift from a higher gear.

Which is probably why my method works.

I like to put it in 1st just prior to stopping and hold my foot on the clutch.

Best,
Grady

I'm sure it's OK, but a lot of us were trained not to do that because of premature TO bearing wear. This on American iron like one of my old Corvettes. Especially the ones with the monster pressure plate.

[Jeff Alton]

I am just curious, why do you put it in nuetral? I always stay in gear incase I need to get the heck out of the way of something in a hurry. Happenned more than once!

Back to your qusetion, What Grady said, and I also have used Zeke's method frequently.

Jeff

Jeff

[mwbaum]

To prevent the neutral-to-first crunch....both touching 2nd and/or a quick throttle blip before going into 1st, will work very well. I usually just blip the throttle and it slides right in.

When the car is cold, the throttle-blip between 1st and 2nd is very helpful also.

btw I have a new clutch in perfect adjustment courtesy of JW, so I know my technique is not covering up a mal-adjusted clutch fwiw. The 915 is really a most pleasurable tranny to drive when you learn its little tricks. I prefer it to trannies where you can not really feel what is going on.......same reason I like Porsches over other sports cars.........because you can really feel the road.

[911pcars]

"I am just curious, why do you put it in nuetral?"

As Zeke said, shifting to neutral at a stop reduces wear on the TO bearing. If the car is stopped but gear selected (clutch is disengaged, i.e. pedal down), the TO bearing spins.

In addition, long periods of clutch disengagement exerts pressure (pulling or pushing as the case may be) on the pressure plate which is bolted to the flywheel which is bolted to the crankshaft. Main bearing thrust bearings take up axial play and can prematurely wear out (resulting in more play) due to excessive "I put it in gear" stops.

Sherwood

[Sonic dB]

I like to put it in 1st just prior to stopping and hold my foot on the clutch.

Does that put excessive pressure on the clutch and throwout bearing?

[911pcars]

yes. err, no. Not excessive pressure since that's the normal clutch/declutch action. However, it's the constant pressure that puts abnormal wear on the crankshaft thrust bearings.

Sherwood

[bigchillcar]

i have a '74 and agree...touch 2nd before going into 1st as zeke says...also, the clutch cable will require periodic adjustment...when it starts grinding using the above procedure, it's usually time to adjust (i.e. tighten a little) and then it's all good.
ryan

[Sonic dB]

Not excessive pressure since that's the normal clutch/declutch action. However, it's the constant pressure that puts abnormal wear on the crankshaft thrust bearings.

Right. Thats a better way of saying it

[Jeff Alton]

Excess wear? How much are we talking here. I guess I am thinking of a regular stop where you get to go on the next light. Not sitting there for long. I have been driving this way for 20 years and only ever replaced one clutch, and that was due to wear on the friction disk. Yes I agree, the throw out bearing is seeing more load with the car in gear and the clutch in, but leading to premature failure? Maybe in theory. But then my normal driving does not include all that much stop and go traffic and maybe that is why I do not see the wear.

Jeff

[DarrylD]

My 911 had a new clutch cable installed and adjusted less than 500 miles ago by JW as well so this is all about a tired tranny. Not to mention all the shifter and shift coupler bushings are brand new as well. I had read about the reduced wear on the TO bearing and pressure plate from several sources and began the practice of shifting into neutral at prolonged stops (like long traffic lights and fast-food drive-thru lines) almost 15 years ago with my first Porsche.

I was mostly wondering about how many more miles I can get out of a tranny in this condition and it sounds like I can baby this one for quite a while using the 2nd gear syncro "spin-up" technique suggested.