How does your 911 shift?
 

I'm not happy with the shifting of my 1978 911 SC (915 tranny). I have heard the 915 tranny just doesn't shift nice, but I cannot believe it came out of the factory like this. The following are my problems:

1) When stopped at lights in neutral, I need to shift to 2nd then 1st, otherwise if I go directly to 1st from neutral the gears grind.

2) The above also applies for reverse. first I must be completly stopped. Then put it in 2nd. Then put it in reverese.

3) When stoped, sometimes you cannot get into 1st gear. It like the gear teeth are directly facing each other and cannot go in. The remidy is to shift to another gear to move the position of the gears, then shift to 1st.

4) When shifting from 1st to second I need to pull hard to get the gear in and when the gears do go in you hear a "clunk" (not grinding) and can feel the gears mesh in. If I try and race at the lights, forget about shifting quickly from 1st to 2nd. The gears will grind. The same applies to shifting from 2nd to 3rd.

How does your tranny shift? I read in a previous post someone clean the exterior of his tranny and then it shifted real smooth. Are they that tempermental?

Tony
'78 911SC

Its real hard to tell whats a problem or not because everyone had different standards they are comparing it to... I'm sure the experts here will give you lots of advice for things to check, but here's my two cents:

I had just about the same observations about my '78 SC/915 tranny. Not the problem with needing to go to second to get to reverse, but the general observations that second is hard to shift into and sometimes first just doesn't want to go. Having no porsches to compare it to, it made me wonder if it was normal. I have had it to two different shops for unrelated items, and asked them to take it around the block. Both places said "yep, thats how they feel." One also mentioned that it requires a slower, more deliberate shift than most cars.

Doesn't mean there isn't a problem somewhere, but it seems that it really is a quirky aspect of the car.

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Regina

[This message has been edited by IXXI (edited 04-19-2001).]

These are typical problems, unfortunately. But the 915 isn't a poorly-designed transmission. It's just prone to wear on the synchros and other components. Do a search on this site and you'll find lots of similar postings, along with advice on DIY rebuilding and sources for rebuilt 915 units.

http://www.pelicanparts.com/ultimate/Forum3/HTML/003511.html

http://www.pelicanparts.com/ultimate/Forum3/HTML/003597.html

http://www.pelicanparts.com/ultimate/Forum3/HTML/004948.html

http://www.pelicanparts.com/ultimate/Forum3/HTML/005619.html

http://www.pelicanparts.com/ultimate/Forum3/HTML/006209.html

You'll also learn about Swepco 201, a gear oil that is uniquely helpful to 915 transaxles.

I had your exact symptoms on my 73 when I bought it. I had the transaxle rebuilt, and the problems all went away.

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Jack Olsen
1973 911 T (3.6) sunroof coupe
jackolsen@mediaone.net

Have you checked the obvious? Perhaps your clutch is out of adjustment and is not fully releasing when you push in on the clutch.

Kurt V
72 911E

Yes! I have a '78 that has the exact same problems. Forget about shifting into first if I'm at all in motion (grinding). Still difficult at a standstill but if I move the car a little I can coax it in.

I don't have trouble with 2nd to 3rd.

I am going to try the shift coupler and bushing repairs mentioned in numerous other posts. It is just a matter of finding the time. I think the only fix for the first gear grinding is a repair of the syncho's.

Mine sounds much like yours, Tony, but not quite as bad....
Certainly have to wait and put it slowly into first at traffic lights and sometimes have trouble getting it out of first and into second. I'm just so used to it now I forget....
Anthony

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'75 911S Targa
'81 BMW Alpina C1 2.3
http://member.aol.com/asaffery/my911s.html

I was having the same problems in my '83. I just replaced the clutch, and now the gearbox actually stops spinning before I try to shift. The difference is unbelievable!

The best part is that it was a lot cheaper than cacking open the tranny and replacing synchros.

Magilla

That really sounds like a cable adjustment problem to me. When your tranny goes, it's gone. There's no grinding, the gear just isn't there anymore.
I'd adjust the clutch with a few 15mm wrenches, tighten up the pedal, and take it around the block. If there is absolutely no change, then you might want to try other problems.
If you can pull the clutch pedal forward, or if it sets farther back than the brake pedal, a simple adjustment may well be what you need.



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Kurt B
'84 Carrera Cab.
carrera_cabriolet@yahoo.com

Just put in an overhauled coupling between the gearbox and shift rod. Found one of the bushings on the old one totally missing, it had fallen apart and was lying in the bellows.

Did the adjustment as per the Pelican Tech article and it is much better. Next project is to put Swepco in the box and believe that then "life will be good"...

You might check your bushing and coupling, then the adjustments, then next step would be to go the swepco route. I was just surprised to find the complete bushing gone and the feel of the shifting was not that bad...

JA

The 915 is just a notchy bastard in first and second. Grinding should not happen though.

All of the 911s I have driven were about the same with the 915 tranny.

Reverse lock out is common in a lot of transmissions. Just figit with it and it will go. Usually I just double clutch it and it will go into reverse fine.

The only way I got good with the fast 1>2 shift is by going to an autocross school and doing a accelerate then brake exercise over and over again. It takes time to get it down without missing the shift. Also the higher revs you have the easier it is, when you are tinkering around town this shift is pretty tough.

Swepco is a very good tranny oil and calmed my 915 down dramatically.

Good Luck,


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Adrian Pillow
1979 911 SC
1966 VW Microbus
PCA - Peachstate Region

I had the EXACT problems you state...

first of all, reverse is a non-synchroed gear...so you must depress the clutch at stand still for 4-5 seconds before shifting...and if there is resistance pull back into neutral and try again...

My 1st synchros are extremely worn and I have to treat it like R...when my speedo is a quarter inch below 15, and I have been pressing the clutch I can ease...ease it into 1st...

second, sometimes I have to pull into neutral and try again...

but one solution I have found is take a look at the underside of your car...
look at the transmission bell housing where it meets the engine...if your car is like mine there is ALOT of crusted oil on it...and it is all over the cable linkages...

take 3 cans of brake cleaner, and a wire brush...put newspaper under the car....lots of newspaper and scrub away...you may have to take off the Heat exchangers...

but after doing that ALL of my 915 problems went away or were improved...no grinds so far (I still treat 1st and R the same) less trouble getting into 2nd, and generally the shifting feels better. I think I freed up some cables and my cluch too, I don't chatter any more either...definately clean your transmission

hope this helps

1,2, and 3 are very normal. The 1st gear synchro on the 915 is pretty weak. Test drive a few cars and you will find most are shot.

It is always a good practice with a 915 to shift into a different gear before shifting to 1st from a stop. The other synchros last longer and doing this will help save 1st.

Sounds like your 2nd synchro is borderline as well. This is not so normal. Try the swepco 201, that may help. But assuming you don't have any of the other problems listed above (eg. misadjusted clutch) you may be ready for a rebuild.

My '83 SC exhibited the same problems. The only thing that stopped me from leaping into a major transmission rebuild was the previous owners' maintenance bills showing a synchro rebuild and a new clutch. So, I worked on everything else in the following order; new gear lever linkage bushes at the gear lever, connecting rod and the knuckle joint. Result, very little difference. Second, new clutch cable and a pedal box bush rebuild, and swepco gear oil. That did the trick. I think the biggest contribution was the pedal box rebuild. The clutch crank lever bush had almost worn through and the main pedal spindle was fractured and bent where the clutch pedal is attached. Whereas before the clutch was really heavy and tiring to operate, now it's smooth and light and travels the full specified 25mm travel at the spring helper end.

'83 SC Coupe

Always start with the simple things first: Clutch adjustment, linkage adjustment, good clean fluid at the right level.
Almost all 915s benefit (some very dramatically) from those things being looked at and put spot on.
Only once those things are confirmed correct would I start to worry about more involved repairs.

Thanks for the info guys.

Just this night I changed my tranny oil to swepco 201. I had put in new tranny oil about 400km ago and was waiting for it to clean the tranny before I put in the swepco.

The flush to swepco shows some improvement but not a magical difference. I just went for a test drive, and I was capable of making some fast shifts from 1st to 2nd without any grinding. I find technique also plays a big role in making quick, clean shifts. I find I need to fully press on the clutch very quickly and then shift. If I take my time pressing the clutch all the way down I'll get grinding.

Also when stopped and going from neutral to 1st, if I give it one second after pressing the clutch it will now go into 1st without having to first shift to 2nd.

I have already checked the pedal bushings and they looked OK. They were the bronse type so they must have been replaced recently. My clutch cable has been checked and has the required 25mm movement. However I will replace it since many have seen big improvement from replacing the cable. Tranny mounts will be next after the cable....the fun never stops.

Tony
'78 911SC

Tony, you've got the right idea. I'm actually thinking of making the "Dr. 915" page on the Gallery site. There's always been a lot of talk about the 915, and several folks on this forum have extensive...uh, experience "working" their 915s.

There's several factors that concern the 915's ability to shift easily.

1. Technique in shifting. You need to press the clutch in *quick*, and *all the way*, to make this transmission work. Unlike other cars, where a lazy clutch foot was OK, you need to really focus on getting that pedal all the way down if you intend to shift with any differential in the engine speed and gear ratio. The flipside of this is that you can theoretically shift gears without clutching, if your match your engine speed to actual groundspeed correctly. I've never done it - I'm chicken that way - but people talk about it. I've also heard that the 915 shifts "better" when the car is being driven hard - e.g. at higher engine and groundspeeds - but I haven't really seen any evidence to support this.

2. Bushings. There's a few critical bushings in the tranny that make a huge difference in feel and shiftability. First, the ball cup bushing at the base of the shift lever. Next, the shift rod bushing there next to the ball cup. Further back, we have the two plastic bushings in the shift coupler, which wear out periodically. They're supposed to not have any lateral play *at all*, but exhibit a little fore-and-aft play. Newer bushings don't even allow the fore-and-aft play for a more "solid" feel.

3. Lubrication. There's always going to be a debate over whether Swepco transmission fluid makes a difference, but IMHO if you have everything else in your transmission adjusted correctly and with fresh bushings, changing over to this stuff is pretty dramatic. It's very thick when cold but warms quickly to a wonderful honey-like feel in your transmission - it's very nice stuff. Well worth the $40 or so you'll invest. The shifter needs lube too - I used regular moly grease on the interior parts. Also, hit your pedal cluster periodically with some 3-in-1 or other lubricating oil every once in a while to keep it from binding.

4. Adjustment. There's several places to adjust the 915, as well. First, the shifter - you can loosen the coupler behind the rear seat plate, and actually adjust the positioning of the shifter. This makes a pretty big difference in feel and ability to get into certain gears (like reverse and 2nd gear). There's some tutorials on Pelican's site on how to do this. Next, the clutch cable has a couple of adjustments - free play, which is adjusted on the throwout lever itself (on the tranny), the Bowden tube tension (the hard tube containing your clutch cable, under the car), the cable length (adjusted with the trunion pin attachment at the pedal end of the cable, and the throw adjuster which is the pedal stop mounted in the wooden floorboard. All that stuff has to be adjusted pretty well for the tranny to even operate.

5. Clutch cable. The most dramatic change I made to the system was when I replaced the clutch cable on my 15-year-old 911! It went from feeling like it had a bad throwout bearing to having a completely new tranny. It also forced me to adjust the cable and get it right, which was pretty tough, but very worth it. It's a $50 part that will make a huge difference if your cable is worn or just old and underlubed.

6. Clutch and other internals. If you're clutch is worn out, or has a blown center, or a bad throwout bearing, the tranny needs work. No amount of lubrication or adjustment to the rest of the system will fix a blown synchro, either. So once you've performed all the above maintenance, you simply have to break down and get it done. A rebuilt transmission from Vertex runs just over $1000, and you can replace your clutch at the same time. You won't have to worry about the damn thing for a while, at least. http://www.pelicanparts.com/ultimate/smile.gif

I'm convinced that a 915 that shifts poorly can at least be made 20% more driveable by attending to the above issues. It's been a pet peeve of mine since I got the car, and I've investigated a lot of avenues to make it better.

Hope all this helps!

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Mark Szabo
1986 911 Targa 3.2
1987 Escort 5-speed 1.9 RIP
The Porsche Owners Gallery

OK, now I'm interested in this Swepco stuff. Since I don't know what the PO put the transmission, is there any way to identify if it is swepco? Would it compatible, or is there a specific change-over process?

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Regina

Tony,

I have a couple of questions for you ... have you ever driven a car before with a cable-actuated clutch? And, are you really expecting to be able to shift into reverse while the car is moving ... and not have problem? If you are sitting at a standstill, and shifting into reverse is hard or grinds, then you have dragging clutch disk that is not fully disengaging, or your shift linkage needs adjustment, or both!

Your problems sound like the clutch is dragging and never fully disengaging! Most likely a worn and frayed clutch cable. I find it rather amazing that people continue to drive 911s with ongoing shifting problems and tend to bellyache about the 915 ... rather than fix the problem!

Driving a 915 with shifting problems is a Self-Fulfilling PROPHESY!!! If you don't fix the problem within a hundred miles or few days of encountering a problem shifting into 1st or 2nd gear ... I GUARANTEE you will wear out the synchronizers, dog teeth, and operating sleeves ... then you DO, IN FACT, have a 915 that needs replacement or rebuilding!

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Warren Hall
1973 911S Targa

Swepco is blue

This topic comes up often, on this board. I would do a search for some of the possible remedies. I had my 915 totally rebuilt, several years ago (new syncros, bearings, gears, etc.) it shifts perfectly, so I know a properly set up 915 with the linkage adjusted can shift as well as most other transmissions. You have to realize that unlike most trannys, where the linkage is attached directly to the tranny, yours is in the rear so it can't shift as smoothly unless everything is adjusted properly. Good luck......


Bill Carcot
1979 911SC
Diablo Region, P.C.A.