nixtfy

78 sc No grinding and the clutch engages. All other gears shift fine, but first is blocked and will not go into gear. This has ocassionally ocurred where first is hard to go into, but now I am having no success no matter how much I try to finesse it into first.
Any suggestions before I take it to the mechanic would be appreciated.

Peter Zimmermann

Head for the shop! I would guess, that, like in some recent threads, that enough of your dog teeth have broken off that the synchro ring has moved out of position just far enough to prevent engagement. If the oil is drained there will probably be some small teeth stuck to the plug's magnet.
Pete

nixtfy

OUCH Today I drained the fluid and found one tooth at the plug and a few more when I took off the cover. Now I am wondering if I should pull the motor and tranny myself then give the tranny to my mechanic to rebuild. I have the 101 projects and the Bentley Manual. My experience has been changing out maintenance parts on my newer cars. If I take the tranny out myself I will save about $650.00 including $150 for towing the car.
Asking for opinions on if I should just bite the bullet to avoid frustration.

SeattlePorsche

Can't shift into first? I know the feeling. Well, actually mine wasn't that bad, just a little grindage that I hear they all develop after time. I think it is a good idea you have about pulling the tranny and motor out and bringing it in to the shop. Will cost you about $2200 dollars. The parts alone, depending on what you have done, are about $1100. That's what it will cost me for new dogteeth 1/2, new brake bands and shift sleeves 1/4. You might need a new 1st syncro hub, the thing they call the spyder, and maybe 1st thrust block/anchor blocks too. Just a guess from me, a new mechanic though.

Once a mechanic has the tranny, there really isn't much to disassembling to him (it was quite a bit for me though.) So I think it is cost effective to pay the extra and let him do the whole thing for you. The tranny weighs about 125 lbs, so I could lift it and put it into the back of my jeep by myself. Turnaround is about 2 days, depending on the parts availability. 1st shift sleeves are hard to find sometimes they say. I think John Walker does it locally here for about 5.5 hours when the tranny is out.

Do you mind posting a picture of what you found when you drained the fluid? Thanks.

Oshin11

When my car is just turned on and cold it is hard for me to shift into first, and sometimes reverse too. After I place it into 3rd, it easily falls into first. Am I going to have the same problems in the near future?! *cry*

Peter Zimmermann

Oshin11: Sounds like clutch trouble/adjustment to me...
Pete

nixtfy

Just had it towed. The pics. of the parts I cannot upload, but if I best described them it would be 4-5 teeth. I did use a magnet in the drained fluid though and 2"-2.5" in length band in the shape of a rib had come out.

Peter Zimmermann

Once you know that a brake band got loose inside the trans a very close inspection of all the gears inside the center housing will be mandatory. Rarely, but it does happen, when that band gets loose it can jam between two gears, and chip or damage teeth on those gears. Expect to need, at the least, a 1/2 slider, 1/2 synchro rings, blocks and bands and dog teeth as necessary. Hope that it's not too bad!
Pete

rbuswell

Pete:

This thread has been an encouragement because of your above post. The PO for my car told me that they "... all shift hard into first" and being the gullible type that I am, I believed him. Mine doesn't really crunch or anything, I just need to really force it into first or sometimes reverse but it doesn't seem to be much different depending on whether the car is still cold. The clutch seems really strong and the car only has 80K on it and all indications are that the car has been pretty pampered so I am more suspicious of the cable adjustment.

The PO installed a new clutch cable so I suspect he didn't get the adjustment right. Is this a matter of making minor changes until it gets better or is there a process I should follow to make the adjustment just right? Thanks.

Peter Zimmermann

My call regarding the hard into 1st or reverse cold was based on the fact that both gears offer resistance. If the complaint had been for 1st speed only I would have leaned toward a synchro problem. In my experience, when a complaint was made like the one by Oshin11, I found the cause to almost always be clutch related. The following can occur:
1. Mis-adjustment of the clutch in an otherwise properly maintained car.
2. A clutch cable failing (or an aftermarket cable that is more than 6 mos old).
3. Some form of wear in the cable/linkage that could cause the adjustment to change, or...
4. Trans fluid, leaking from a defective mainshaft seal, contaminating the clutch.

When the complaint is a balky 1st speed only, with reverse functioning properly, I lean toward that synchro. In a properly driven car (w/915) synchro wear takes place slowly over many thousands of miles. First, the friction material on the synchro ring begins to wear away, and the ring goes out of tolerance. After that, the gear becomes more difficult to engage because the slider has to find a happy place to compress the worn ring, which in turn must stop the gear, which in turn allows the slider's teeth to engage the dog teeth on the gear. This is first noticed, usually, when parked at a traffic light, in neutral. The light changes, you shift into first, and it's like pushing your hand against a wall. You back the lever out and try again. It slips right into 1st, like nothing ever happened. Over time this symptom will become worse, and that's when the first cold 1st gear shift also gets worse. The next bad thing that happens is you go to shift into 1st, at the traffic light, and you have a no-go, the guy/gal behind you leans on the horn, you get frustrated and jamb the trans into gear. With luck you found a happy spot, if not, along with the horrible engagement crunch, you probably broke off one or more dog teeth. (NOTE: This is why I've posted in the past to sit at the light with 1st gear engaged, done gently just before the car came to a full stop. That's the easiest way to add many thousands of miles to your 915.) As time passes you occasionally crunch 1st gear, often times losing one or more dog teeth in the process. Eventually, enough of those little teeth break off and allow the synchro ring to pop out of position, which will prevent the gear being engaged. That's the best scenario, the worst is when the slider attempts to engage the dog teeth, enough teeth are already gone to allow a brake band to get loose, broken stuff starts flying around inside the trans, bouncing off of other gears, etc.

Now, to address the cold start bad engagement of 1st speed. That also can be a situation where technique can add thousands of miles to the life of the trans. Every 915 has got at least one gear that it likes to have engaged after a cold start (in my '82 2nd or 3rd work equally well). Find that gear in your trans, and use it every time you cold start the car. Engaging that gear is the first thing that you must do before attempting to engage 1st or reverse. The oil starts moving, the reverse idler stops moving, parts line up, etc... You won't believe how much more you'll like your car after you start using it this way, and it'll like you more back.

Regarding clutch adjustment: There is only one "correct" adjustment, any other setting is wrong. The specific procedure is found in the factory repair manual, but I think that I posted the how-to-do-it in another thread some time ago. If you need the procedure I can write it again.

A last note. Unfortunately, with synchros, mileage is not usually a usable benchmark. I've repaired 915s with less than 50K miles, and I've driven them in good operating condition at 150K miles. Yes, 1/2 synchro repair done between 75K and 90K miles is common, but not ordinary enough to point at the speedo and say, "Ah-hah!"
Pete

rbuswell

Wow, Pete you're the best!

I always park in reverse because I've thought it was the lowest ratio so the car was least likely to roll away. I also have a nervous tendency to take the car out of gear at stop lights because I'm afraid that my foot will slip off the clutch. I'll start to experiment with the ideas you wrote about. As for your other posts, I will find them and read them as well.

SeattlePorsche

Pete,

I would love it if you would re-post the clutch alignment procedure. I will eventually have to do this and replace my clutch cable (which was hanging on by a thread, literally.)

Thanks,

Peter Zimmermann

Clutch adjustment, type 915 trans - '77 - 86 models with hook-type cable.
1. Assumptions: (1) Pedal cluster is in good condition, including clutch cable anchor clevis pin & bushing. (2) Clutch cable is o.e. and in good condition (minor, normal stretching is OK). (3) Omega spring under the bell housing is in good condition.
2. Adjustment:
a. Loosen clutch cable at the aluminum holder fastened to diff side cover. This is done by backing off the two nuts on the bowden tube, at the holder, until the cable can be pulled loose from the holder.
b. Locate a short arm, with its own spring, whose free end lines up with an 8 mm adjustment bolt. The distance between the short arm and the tip of the bolt should be 1.2 mm. Like valve adjustment clearance, you should have to lightly tug the feeler guage to remove it, but you should be able to re-insert it after removal. Turn the bolt until the correct clearance is made, tighten the jamb nut and re-check clearance.
c. Slip the clutch cable back into its holder. Line up the black housing (bowden tube) part of the cable so that it's above the throttle lever (aka bell crank) on the side of the trans, and is about one inch away from the side of the trans.
d. Maintain the cable location while you tighten the holder nut. As you turn the nut you will feel the cable (not the bowden tube), near its end hook, become taut. When this happens insert a 1.0 mm feeler guage in between the short arm and the adjustment bolt.
e. Continue to slowly tighten the nut (back off the nut on the other side of the holder as necessary) until you have achieved 1.0 mm clearance, again requiring a tug to remove the guage. Snug down the two nuts at the holder. Be sure that the bowden tube is about an inch from the trans, and that you have a lock washer under each nut at the holder. Double check your clearance and call it done. You will not use the adjustment bolt again.

Now, there are a couple of other points:
1. You can't adjust this system by checking free-play at the pedal, so don't bother.
2. If you still have a release problem after doing the above you might have to adjust the pedal stop at the clutch pedal. To do this loosen the two allen head bolts, slide the stop up a couple of millimeters, tighten and test. The carpet section at the pedals must be removed to do this.
3. If you can't achieve the above 1.0 mm clearance by using the holder nuts to tighten the cable (DO NOT use the adjustment bolt to make up the distance!) there is a strong possibility that the cable installation at the pedal cluster must be changed. Remove the pedal board from the car, and find where the clutch cable attaches to the clutch pedal arm using a clevis pin and clevis (fork). With a dentist mirror and flashlight look at the cable threaded section at the clevis fork jamb nut to see how many threads show (you can also see this by depressing the clutch pedal). I've found that a good basic set-up is to have 6 cable threads visible from the jamb nut to the end of the threaded section. If this is not the case, you have to disconnect the cable under the car (by loosening the two holder nuts and pulling the cable loose). Then you have to remove the cable clevis pin, and pull the cable as far from the tunnel as you can (usually a couple of inches), loosen the jamb nut on the clevis and turn it until about six threads show, then turn the clevis until it's against the nut. While the cable's disconnected always check the tiny, white clevis pin bushing in the clutch cable arm - its hole should be nice and round. If it's egg-shaped it must be replaced. Likewise, check the clevis pin, it too should not show excessive wear on the shaft that rides inside the bushing. Re-assemble and, if changes were made, re-adjust the system under the car. You will find it easier to connect the clevis and pin to the arm before you re-tighten the clevis jamb nut.

Hope all of this helps!
Pete

Peter Zimmermann

James: Definitely install your clutch cable before you re-install your engine and trans. Seating the bowden tube at the firewall is much easier, and as you lift the engine and trans into the car you can easily guide the bowden tube into position. You can also do the complete hook-up at the pedals using the above steps.
Pete

Early911

Is there a different procedure for a '74? If so any idea where I can find it?

-Mark