Potential transmission woes?

[dd74]

Moving rear to front with my 911 queries, here's another question for the good people of this forum. It involves my 915 transmission:

How do I know when either second gear or the second gear synchromesh might be on their way south? I'm not well versed with transmissions; for example, does each gear have synchros or is synchomesh a part of the gearbox as a whole that works with all five gears? Nonetheless, during spirited driving, sometimes second gear grinds before it's engaged fully. This happens, naturally when going 1st to 2nd or 3rd to 2nd. When this gearchange is done slowly, or with attention paid to more precise shifts, there's no problem. In the future, I will be adapting new shift bushings and a short-shift kit to my car, but I'm not sure this will rectify what could or could not be a problem. Is this just a 915 thing, or might it go deeper than that?

Thanks to all...

[tummi]

This is a very 915 reply,

you can find a lot of discussion on this board about this transmission. If your 2nd is grinding, you may be trying to shift too fast into it. Give it the 1-mississippi pause and see if that helps. I am still trying to get the thing to downsift to 2nd without popping out. Sometimes i get it right and no problem, other times it kicks my ass if i'm just not right. This I think is more of a worn syncro type of problem. It just pops out. I think you're supposed to learn to love this if you don't want to fix it type thing.

[ChrisBennet]

It's the nature of the animal that 2nd gear wears fastest. Like you've already figured out, shifting slower from 1st to 2nd will help. Blipping the throttle or double clutching when going from 3rd to 2nd will also help.

"Syncro mesh" refers the helical cut gears used to keep noise down. Your reverse gear is "straight cut".

The "syncros" (syncronizers) are a wearable item that speeds up the gear before it gets locked to the drive shaft.

If the transmission is popping out of gear I would fix that problem before driving the car further.

-Chris

[NYSCAR]

Regarding the popping out problem, have you checked your shift coupler bushing and tried re-aligning your shifter? if it is aligned too far forward or if your coupler bushing is worn you might not be 'putting it all the way in gear' before the shift lever stops when pulling it into 2nd. Just a thought.

Brad

[Wrecked944]

"Regarding the popping out problem, have you checked your shift coupler bushing and tried re-aligning your shifter?"

Whoaaaaaa...may I ask for a more in depth explanation of that comment? My 915 pops out of first gear and so I was/am planning to drop the tranny and rebuild it. And while I am excited at the prospect of playing with tools and such, I'd also be interested to know if there is possivly a relatively simple solution to my problem which would allow me to drive my car longer before the rebuild (right now she is off-road awaiting the rebuild). So may I ask you to give a "Dummies Guide to Shifting" explaination of the shifter coupler/bushing thing?

Thanks,

[Zendalar]

During my rebuild I tore the gearbox off the leverage..well from the adjustment point, so I lost the adjustments and had to redo it. What I found out, that even though I did just as the Hayne's manual told me to do (turn shiftknob all the way to the right and the axle from the gearbox to the left while neutral, tighten and drive) 2nd and 4th gears popped out too easily.

The manual did not mention anything about front to back adjustments. What I did was loosened the adjustment bolt thingamob a bit and just slightly and very carefully pushed the shiftknob towards the front of the car..just so slightly that it moved maybe one or two millimeters at the axle. Retighten and drive.

If you change gears directly from the gearbox (with your hand) you feel the clicks and such and you can imagine how it must feel at the shiftknob. You know when you got it wrong...I did it trial and error way.

This might help , but adjust very carefully or you might end up with popping 1st and 3rd gears.


EDIT: If your 1st pops out, do it backwards...move the shiftknob to the back when adjusting.

[Leland Pate]

Ok dd74,

You are going to have to do something with that avatar...

I can't seem to be able to read through your posts without it coming out in true Daffy Duck tounge...

Seriously, check your clutch cable for wear and/or adjustment.
Check the condition of the shift coupler bushings and adjustment of the shift coupler.
Check the condition of the actual shift lever linkage, lubing and replacing worn nylon bushings if found.

All of this stuff can be found in detail in the Tech. Articles on this site.

If all of these things are good, then you may simply have a worn out set of synchros.


Start with the cheapest fixes and work your way up.

Some people have also said that it helped when they replaced the clutch helper spring... if your car has one equiped.

[NYSCAR]

Janus and others, the shift coupler thing is really a very simple thing. The best thing to do is get in there and look at it, things become apparent really quickly On my car (early car) there is a removable panel on the center tunnel just in front of the rear passenger seat (if you can call it that). I assume it's the same on your 911 as well, but I'm not sure. Remove it to reveal the shift coupler connecting the shift input shaft on the transmission to the long rod ultimately linked to your shifter. The main purpose of the coupler is to link your shifter to your transmission with a flexible bushing in the middle of it to dampen vibrations. Try moving your shifter around while watching what the coupler does. Looking rear to front direction, if you move the shifter left, the coupler turns clockwise. Shifter to right, counterclockwise. Pull shifter towards rear of car, moves the rod towards the front of the car. Push shifter to front of car, moves the rod towards the rear of the car. Two things:

A) check your coupler bushing for wear...in my case mine was essentially gone, and i was surprised how i was able to even shift (i was occasionally getting a grind shifting from 5th to 4th, turns out i was actually just touching reverse *cringe*). If it looks good, leave it alone, if it looks the least bit worn, replace it.

B) adjustment may be necessary anyway. The shifter itself has a limited range of movement. So if the coupler isn't adjusted far enough back on the rod coming from the transmission, then when you pull the shifter into second gear, the coupler might not be pulling the shift rod far enough forward to engage second (or i might *just barely* engage 2nd, and pop out later).

Wow that was alot, hope all that blabbering makes sense....

Brad

[dd74]

I wouldn't talk about ducks when one has the name "Pate."
Oh, and Daffy is an avatar.
But it doesn't take a "quack" to know that, right?

I couldn't resist...

But seriously, thanks for the advice, long-billed as it is. :>

[Wrecked944]

I've gotta add my thanks as well...those explanations are immensely helpful and I will be certain to pop open the access panel and check my shift linkage once the "Biblical Deluge" ends here in New England (I believe LesPaulGuy - who lives in eastern Mass - is having flooding problems in his car !!)...but seriously, I think it is definitely worth investigating. Given the condition of my car at purchase, I'm 110% certain that no-one (or at least no-one competent) has ever touched the shift linkage.

And as for avatars...I think Leland is on to something...we should have wav files associated with each posting. Click on the avatar and the posting will be read aloud through your computer's speakers using the voice of the designated cartoon character. I, of course, would use Ee-yore.

"Oh Pooh, we've stripped another gear. That was our last one. Looks like we're going to have to get out and push it around the track...*sigh*..."