Let the game begin, 60 miles from home and no clutch!

[zotman72]

Leaving Boulder this afternoon after visiting my son @ CU and Speedo (Lars) at his business. I accelerated briskly away from a stoplight in my SC and my second gear change was interrupted by a pop and the clutch pedal going to the floor.
I pulled into a parking lot to check what was up. I was thinking pedal cluster area for clutch cable to have popped off. Nope. I am thinking nuts now. Slide under as best I could the lowered rear end of the car to look at the clutch lever. This item came off in my hand.



So my options were:
1) call a tow truck (my insurance covers 12 miles tow) and I was 60 miles from home.
2) call and convince my sick wife @ home to go get our Tundra and then our race car trailer and then drive 60 miles to come get me (NO CHANCE!)
3) Cajol Speedo to save me.... Quick call confirmed fears, Lars had other obligations... and no functional 911s in his motorpool to loan me if I had my 911 towed to his mountaintop home
OR
4) Drive home without a clutch. Starting in 1st gear and synchro shifting.

Option 4 was chosen and after a quick mental rehash I set off. My 915 was rebuilt 2 years and 10K miles ago by Storz.

Well it was a fun adventure and memorable experience. Never a dull moment
when you drive a 911. I will replace the cable this weekend, simple fix.
YMMV

[Rot 911]

That is what makes driving these cars an adventure. People that just drive new cars would have just thrown up their hands and called a tow truck.

[jtfreels]

Well I sympathize with you, I had to do that once, only 4 miles through town, with some strategic running through stop lights. Hopefully most of your 60 miles was non stop?

Jay

[MarKoBrow]

I did it once from Syracuse,NY to Philadelphia,Pa picking up my daughter from school with my then and now ex-wife in my 4-Runner. In my case I didn't want to wait there with my ex-wife talking to me

[ben parrish]

I had to do it once. About 50 miles. Started in second gear and timed the shifts/rpm's. Definately not fun but not too bad. I had to go through a lot of lights and stop signs..thank God for a strong starter.
Once you were on Hwy 36, at least you didn't have any lights to worry about until you got off at Dry Creek. Glad you made it safely.

Ben

[jimbauman]

Originally Posted by Kurt V

That is what makes driving these cars an adventure. People that just drive new cars would have just thrown up their hands and called a tow truck.

LOL!! So true... so true.....

JB

[butzi73]

Would somebody be kind enough to explain the actual mechanics of this technique?

[zotman72]

Ben you know mydrive, absolutely right it was a straight drive in 5th once I got to 36. Three stops on Dry Creek and I was at my home. I never doubted I could do it but a couple times finding 2d was a challenge. I found 3rd & 5th easily and did not need 4th. Having the 3.0 torque made far easier than would have been with my 2.4S MFI recently converted racecar.

[Mitch Leland]

Butzi,

I'll give it a go... I've done it with my car, it's sweaty arm pits, at least for me. You turn off the engine, put the car in either low or second gear, I believe I used second ?, then start the car in gear. Drive along to a normal speed in that gear push slightly down on the accelerator, let up and at the same time move the gear shift into neutral, blip the accelerator (match the engine speed to the transmission) one more time and positively push the gear shift into the next gear.

If you screw up, then don't force it. I can't remember if you start over by stopping and running through the gears again or? Maybe Zotman will chime in...

[Laneco]

An A+ number 1 super-great guy in Boulder is Kevin Farrell - Injection Labs.

I say that with open bias as he built a terrific engine for me (and is building a most wicked second engine...). His engines are measured in screams per mile!

angela

[Grady Clay]

Guys,

There isn’t any way to drive a 911 not using the clutch without transmission damage if you shift while driving.

Yes, you can start in a gear, say 3rd, and continue to drive without shifting and do no damage.


The reason is the synchronizer. In normal operation the friction of the syncro is only required to overcome the inertia of the clutch disc and some transmission parts. A job it is designed to do for many thousands of miles.

When shifting without releasing the clutch and attempting to ‘match rpm’, The syncro friction can only produce heat. It can’t match rpm. While you try and find that ‘sweet spot’ where the dogs will engage, you are frying the syncro ring and the mating surface on the sliding sleeve.

To make matters worse, any ‘clashing’ damages the engagement dogs on the gear and more-so the now too hot dogs on the sliding sleeve. EDIT add: You are no longer trying to overcome the rotational inertia of some parts but have the inertia (and power) of the engine against the rolling inertia of the car.

If there were without syncros, as a Hewland race transmission, there wouldn’t be this issue. The gears engage if rpm are matched and won’t if not. A bit of noise but no damage.

My take is it is worth the flatbed tow and pay the extra $500 or whatever because you can do several $thou$and$ damage to a transmission.

Bill, I hope your skill and luck means you don’t have too much damage.

Best,
Grady

[billybek]

I drove many times without a clutch cable on my old VWs, but when my cable snapped last year on the SC, I just put it on the flatbed and hauled it home.
My reasoning was that it doesn't shift all that well with the clutch....

[fitchn]

Shows you how useful this board can be at times, if you had posted when this happened (and I had checked the board), I could have loaned you my spare clutch cable. Glad to hear that you made it home unscathed.

[Grady Clay]

Originally Posted by billybek

I drove many times without a clutch cable on my old VWs, but when my cable snapped last year on the SC, I just put it on the flatbed and hauled it home.
My reasoning was that it doesn't shift all that well with the clutch....

Bill K.,

Me too. I had that issue with my ’63 VW sunroof and even finished a FV race ~’68 without the clutch. I was worried about damage so I took the VW transmission apart. Everything was still ‘like new’. The difference is in the type of syncro.

Early VWs used a Borg-Warner type cone syncro – similar to the G50. It was less susceptible to damage when shifting without the clutch. Added was the lighter car and smaller engine.

The ‘Porsche Patent’ syncro is exceedingly susceptible to this kind of damage. While the G50 is different, the far heavier car and more powerful engines can easily overcome their syncros also.

Best,
Grady

[ben parrish]

Thanks a lot Grady, Now I have something else to worry about! just kidding. I did this about 75k miles ago and still going strong. No doubt this is bad for your transmission. It's not something you want to do but sometimes you have to do it. I had to do it in my 50 Chevy Truck about a year ago..straight cut gears really don't like this method.

Yea Bill, I used to live in Boulder, then in Lakewood. I traveled that road many, many times. How was that snow two weeks ago?

[Grady Clay]

Ben,

Were you a Rennenhaus customer?

Best,
Grady

[ben parrish]

No, you had closed the shop when I came along. We have met a few times though. Once on a run to Estes park with some Pelican Heads. I think Pat S. was there and empty O and a few others. Another time or two at other runs and the PCA event out in the country. What was that guys name with the Gmund Garage replica at his house? I remember that cool planter he had of the old 356 that was found at the bottom of a reservoir.
Always enjoyed the company and your great advice.

[signature65]

Lets see.....did the same in my VW bug, Speedster, and 911. Clutch cables suck! But there is always a way home!

[Walt Fricke]

I have to disagree some with Grady here. I am reluctant, since he knows more than I do, but that has never stopped me before.

When upshifting without a clutch, if you let the engine rpms drop just enough while you are in neutral, the synchros won't be doing any more work than they would with the clutch.

If you have to blip upshifting to avoid grinding sounds, it is because you waited too long to engage the higher gear.

Downshifting works the same except that the blip in neutral is normally needed to match rotating part speeds.

What you are doing in both instances is double clutching without the clutch.

Note - this is not the same as trying to do clutchless speed shifts on a track or for any other reason. I suspect Grady was thinking more along these lines.

The trick here is getting these speeds exactly right.

And I think that may be a tricky trick.

I thought I was pretty good at this, as I drove a VW bus clutchless from the sand beach on a lake in Nebraska all the way back to Boulder CO after the internal TOB fork broke once. No sweat. I once drove a buddy's broken clutch TR2 or 3 (long ago) through Connecticut to NY on various roads including tollways. No real sweat beyond never having driven that car before, it was at night, I had to follow my car he was driving to know where to go, etc.

Then I had Bill's exact issue (I suspect the source of the break is where the Bouden tube mates with the clutch steel tube coming out of the chassis by the torsion bar tube) driving my 2.7 stock engined '77 up Rabbit Ears Pass. I continued on to Steamboat on the off chance of getting a replacement, then drove home.

This was complicated by the fact that my car wouldn't start in first gear - the engine would not catch, so I had to stop, if I stopped, on a downhill at all times. This had to have been an engine tune-up issue, I think. That added a lot more challenge than my VW oddesy, where starting was no issue at all.

What bothered me, though, was the difficulty I had in getting the shifts right with the 915. Finding the sweet spot, as Bill puts it. I thought I was good at this, since I knew how to double clutch, had done it before, etc. But I think the synchros on the VW (a different system) may be much more forgiving. There I could apply a little pressure at about where I thought things should be, and as revs built or dropped it would just slide into gear and I could get back on the gas.

This didn't work consistently for me with the 915. I had some of that clashing more often than I wanted. Yes, that is doing the engagement teeth no good at all, though I don't think this means instant death for the parts. Not like driving for thousands of miles with worn out synchros and doing normal street shifting.

I think I see what Grady is driving at - when shifting with the clutch disengaged, the engine speed is not driving the mainshaft, and the synchros can more easily bring the mainshaft, and the gears driven directly or indirectly off of it, up to (or down to) matching speeds. And the synchros are going to be creating heat all the while you are pushing on them until things match and it goes into gear. With a working clutch, and good synchros, this is a very short time even with large mismatches.

But if you get the matching right, this should also be a very short time.

Case in point - you have badly worn synchros, and if you shift "normally," you get a clash about every shift. If you take to double clutching, you can shift without the clash. Means you can drive for quite a lot more miles without doing even more damage to the more expensive engagement parts. Though these parts are already most likely to the point of needing replacement.

Grady has built and rebuilt a lot more trannies than I have, so you take my suggestions at your own risk of course. But I don't think Bill should be worried.

Walt Fricke

p.s. - Bill: I'm trying to remember if I have a spare for this harp spring style clutch release. You had no problem getting started in 2d? Cool.

[Roc Doc]

The first year I was in Las Vegs, mine broke on Las Vegas Blvd. at 1:30AM New Years day! i had to drive it from The Mirage to the Flamingo onramp, in bumper to bumper traffic, surrounded by who knows how many drunks, with no clutch. That was some 50,000 miles ago, and my 915 is still alive, although at 225k it's getting a little testy.

Grady, that info about the syncro's is good stuff. Thanks