I was almost home from a Wash & Shine in Danville. After a stop sign, I put the 914-6's tailshifter into first, and as I'm finishing releasing the clutch I got a loud meaty "Bang!" I managed to cruise around the corner into a slightly less awful spot at one of the nastier intersections in Berkeley for traffic.

I took a look at the linkages at the back of the transaxle. The cables and rods I could see still seemed to be connected to something farther up the car, but I couldn't get under and don't know what to look for. Called AAA...

Car's in my garage now. If I put it in gear and release the clutch I hear a suggestion of something rotating, maybe rubbing against something else, but the car doesn't move at all. First, second, third or reverse doesn't matter - same sound. Can't feel any real difference when I move the shifter itself - vague as ever, usual bumps and chunks as I (think I) engage a gear.

Any suggestions as to what it might be, or what to poke at, would be welcome. I was wondering whether to convert the 901 to a sideshifter or move to a 915, Audi/Boxster w/ cable shifter, etc...

Thanks!

I had an issue like that last year, it was my cv that came loose on the tire end. 3 of the 4 bolts were loose, I guest for a while and the 4th one broke.

clarify what the shifter feels like when you go from gear to gear with the engine off... is it fairly normal

I'm guessing the CV blew also

converting away from stock on a street car is not necessary

Mine got towed last week off the 101 freeway after the same bang. CV joint at the transmission.

Been through this a couple of times with different cars.
First time was the CV.
Second time was the clutch.

Thank you all for the feedback!
Well I had the engine running, but when I shifted into gear I felt the things I expected to feel through the shift lever. But when I came off the clutch the car didn't move.

I was told "you can keep the 901 with that SC motor, just don't stomp on the throttle in first gear." I know plenty of folks have happily kept the 901 with upgraded motors.

But I'm liable to abuse first gear from time to time on the street. The other thing is that it might be nice to use this car for track days... (Driver Ed days, no racing) I thought I had time to research the options, but if this problem is in the gearbox and it needs to be touched anyway, these questions come up again...

Thanks again for your help!

... and ALWAYS install new schnorr washers on your CV joints. Some folks recommend installing all new CV bolts as well. Make sure they're torqued to spec too. If one comes loose, others will follow, like lemmings.

curious to hear what you find.

i'm just guessing below.

if all outter cv bolts came out - axle could be at downward slopped angle.

if you put the car in gear - can you push it from behind - i assume so - if you get someone to look under and axle does not turn as car rolls forward, then wheel and axle are not connected.

if cv blew up on the inside - maybe you can jack car up in drive wheel side only - is that passenger side - with trans in gear - try to turn wheel by hand a hear for sounds.

jim

Keep your 901 as it will be plenty for your motor. The 6-cyl does not have the torque that would most likely kill it...nor the traction of slicks. Now if you have a 450 turbo in the 14 that is a different matter...

Go to Fastenal (bolts) and spec out 12.9 - I did that and run over 500 hp. You might want to look at adding better/bigger CV's. Renegade Hybrids make their own set that is bolt-in for a 914 - good for 450-500 hp. These are plug and play - just a thought. I have since moved up to Turbo CV's/Axles but below is a picture of the Renegade units installed in my old set-up. Good luck!

Click to view attachment

If the 901 was strong enough, why did Porsche go to the expense and weight penalty to design and build the 915 when they went to 2.4 liter engines in 1972? Though the 901 will work, I think that it's weak points start to show up.

Upgrading to a stronger transmission, CVs, and axles is never a bad idea. Remember, speed costs money, how fast do you want to go?

Also happend to me on the freeway, scared the #@%$ out of me, all gears gone and I was still going 70mph. It was the CV came off the tranny.

Dr Evil bolts with the wire, never happend again

The CV is an almost certainly engineered failure point to protect the tranz. If the insides are in good shape, the CVs have a tendency to blow first. However, they tend to come undone from loose bolts more often.

The 901 is a fine box for most aircooled /6 engines. You dont hear many problems with a sorted out box and a /6. Bad bearings and weak 1st gears are the internal issues, but a converted box to 4 speed for a more powerful and torquey engines removes the weak location of 1st gear.

Except the rare time this happens

A $5 - 10K transmission upgrade is not for everyone.

That is the 1st gear weak point of which I spoke where too much TQ applied at once snaps the shaft. With high TQ motors, this gear is not needed and is only a liability. Plus, getting rid of that gear saves money as you dont need the 1st slider ($500).

Thanks again, guys. I'll get the jack out and have a look at the half shafts. Forgive the stupid question, but: If only one side failed, why would I have no drive at all - fail-safe feature of the differential? Both sides failing at the same time seems unlikely or massively troubling...

Stock diff puts power to the wheel that is slipping, not gripping. As such, your output flange on the side with a bad CV would be getting all the power, and none of the go.

If you had an LSD you could still drive until you burnt it out.

Stock torque for this motor seems to be just under 200 ft-lbs, Renegade's site claims the 901 is good to 300hp/300ft-lbs - but as Dr Evil was saying, they eliminate 1st gear.

I'd certainly like a six speed box where all gears can be used, but it ain't cheap...

One of my topics for research is where 944 half shafts and/or CVs figure into all this stuff... As a point of reference, Renegade appears to have a "high performance axle kit" that replaces the half shafts for $700/pair.

There are a *lot* of transmission threads on 'World...

Thanks, that makes more sense now!

DRIVER ABUSE

Small update -- the passenger-side halfshaft is loose no longer connected at the wheel end. Have the car up on jack + jack stands, will see what's up with those bolts.

I'd rather deal with that than the internals of a tranny! Good Luck!

Three bolts appeared to have backed out over time, but were still in place on the wheel-end of the half shaft. I guess the one remaining bolt eventually sheared off after taking all the load for who knows how long... I got the remaining three rethreaded hand-tight with an Allen key, about to go find a torque spec from the Haynes manual and see if I can get a driver on them. Then I'll get it out of the garage to check the other side -- too tight in there for the floor jack.

Thanks all around for the tips! Almost feels like I accomplished something today...

Anybody have a favorite tool for removing the sheared bolt-end?

What are you using for bolts? The factory bolts have what is known as a triple square or serrated wrench head not an allen head. If you go after it when an allen wrench you will strip the 12 point hole and then you will be screwed. BTW: you need new schnorr washers too. I've seen them in the bins at my local hardware store.

What's in there now are pretty clearly hex-driven bolts, I just couldn't get a good angle with my camera. I have no idea of where they came from. Didn't want to remove them because I didn't know if they were holding/locating bits of the hub-end relative to each other even not being bolted in, if that makes sense. Didn't want to have a small pile of parts I couldn't put back together without completely removing the half shaft.

I don't consider this fixed by any stretch, just (probably - I'll let you know in fifteen minutes) able to move under it's own power. Appreciate the several warnings about the Schnorr washers in this thread, and the Fastenal bolts, etc. I've got homework to do now about half shafts and the connections at both ends...

I bought this car in late 2006, but only put ~360 miles on it over two years and then it sat for several. Until the week before last in fact. So in many ways, it's still new to me in that I haven't gone through a lot of it (or paid somebody to do so).

since you don't know what grade those bolts are, I would suggest you replace them.

either stock, or correct grade allen head


its time for you to pull the CV's, inspect them, repack them, and put everything on fresh

ALWAYS use new schorr washers....

you were lucky, sometimes when they back out they break the bellhousing of the tranny and rip the starter off.
do you want that to happen....? put new, correct washers on

brant

Once bitten....

Agreed on all points. For the next couple weeks it makes life easier to be able to move the car around under it's own power, but I absolutely plan to do this - with new hardware, factory spec or better. I will have to decide whether I want to upgrade the CVs themselves, or the half shafts as a unit if there's a sensible option there. Though I'd probably learn a bunch by reconditioning the ones I've got...

For what it's worth, I did manage to get a pic of the wheel-end bolts when checking the driver side (all fine). There's damned little information in the 914 Haynes, but the 911 Haynes that covers this motor refers to these as "halfshaft flange Allen bolts." Can't quite make out the visible engraved characters, looks like F, K or R, then E...

Wrong bolts

That's exactly what happened to my 70, ever since I inspect frequently. Especially before long drives.

It'd be interesting to see what washers are under the bolts

Zim's Autotechnik has the best CV's I have seen for the dough. And Rick is right, Schnorr washers and 12 point bolts are essential. Some here wire them on. I did not. I replaced both my old halfshafts and new inner CV's with Tangerine halfshafts, but I am not sure who makes their CV's on either end.

But they are killer made axles, whatever they are.

John

evil's cv bolt kit came with allen head bolts, that said, if 3 of your cv bolts where still holding at any degree, the cv is probably not your primary problem ??

i would think if frist snapped off as in pic above, you'd still have some go, if that shaft is still in the bearing area and semi correctly oriented, but going would be noisey as hell ??

This thread perpetuates the falsehood that Allen head CV bolts are not stock. Horsepucky. They were OE (i.e., "stock") until the triple hex bolts superceded them somewhere in the middle of the production range. The OE Allen head bolts are NOT weaker, and they hold torque just fine. The main weakness of the design is the tendency to round out under repeated use and become difficult to tighten or to remove.

Rant: Why do people make statements that are patently false? Why do those falsehoods get repeated as fact? Why don't people check their facts before posting such drivel? Laziness? Belief that whatever you see on the internet must be true?

End of rant. The Cap'n

I see it a different way. I firmly believe that folks don't say things (in this forum anyway) that they think are false. In addition it's perfectly natural, based on any one person's experience, that there are a lot of assumptions (about any complicated subject)... I'm packin' a few myself!

I also don't mind being corrected when I'm wrong about a topic but I wouldn't want to be barked at because it'd make me feel like my experience isn't appreciated. My shell is pretty thick so it doesn't bother me so much and I respond with "I stand corrected" when needed. But I'd rather it was a simple correction.

It's a good thing that we have folks with a whole lot of experience to share. This list is strong because it's a positive place to learn.

... and I replace the hex-heads with serrated-bit heads every time I can as well.

(residual Memorial Day plug)

Oh yes: I'd rebuild those CV's. It's an instructive process and there are several threads via the search function that talk about it. You're looking for ball-contact patterns that aren't grooved too badly. If there is galling they're toast.

CV's need maintenance (inspection/repacking) now and then to make sure water and dirt haven't gotten around or through the boots. Even folks who are otherwise great at maintaining their cars don't generally do CV maintenance. It's a mess.

I don't like to do it either.

Good luck

Mark,
I think my car has sat as long as yours...maybe longer.
I spent the weekend rebuilding a motor, soup to nuts and got it installed last night.
Its on the lift, all the underbody parts are clean and painted...ready to install.
Just trying to get some shorty manifolds now....
Almost on the road again.

Its got a long list of stuff to do, but its all fun stuff to work on finally.

rich

Grade 12.9 is 12.9. Doesn't matter what head is on them. I replaced mine with Allen head 12.9 as well. Just buy them from a reputable store. Some are made in China, and may or may not be 12.9.

I buy the bolts in bulk from McMaster Carr. Also you should replace the Schnorr washers any time you pull the bolt. Good habit!

Every 4 events I get under the car and make sure all the bolts are tightened to specification, both inboard and outboard.

That way none of the SMART 914 guys come up and tell me I have CV bolts coming loose.

I change out the 12points to allen every time. Its nice to have simple tools to change things. I also wire mine, though. For the outers it requires pulling the hub. Another plausible fix I have heard for the inner ones is to get longer bolts and put nylock nuts on the inside.

I have moved away from using the CV gaskets. The TQ on the bolts is 30 ft/lb. No need for special tools for that. With the gaskets on there is a compression factor as the gaskets give, but still have more to flatten out. Clean install with a bead of high temp RTV on the outside has been my preferred method for the last couple of years.