Something went "Bang!" Now trans is a box of neutrals... Options

[smj]

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!

[914itis]

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.

[brant]

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

[PancakePorsche]

(IMG:style_emoticons/default/agree.gif) Mine got towed last week off the 101 freeway after the same bang. CV joint at the transmission.

[Valy]

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

[smj]

Thank you all for the feedback!

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

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.

converting away from stock on a street car is not necessary

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!

[euro911]

... 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.

[jimkelly]

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

[Cracker]

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... (IMG:style_emoticons/default/shades.gif)

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!

[GeorgeRud]

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?

[jsayre914]

(IMG:style_emoticons/default/agree.gif)

Also happend to me on the freeway, scared the #@%$ out of me, all gears gone and I was still going 70mph. (IMG:style_emoticons/default/blink.gif) It was the CV came off the tranny.

Dr Evil bolts with the wire, never happend again

(IMG:style_emoticons/default/smile.gif)

[Dr Evil]

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.

[Mark Henry]

Except the rare time this happens (IMG:style_emoticons/default/smile.gif)

[mepstein]

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?

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

[Dr Evil]

Except the rare time this happens (IMG:style_emoticons/default/smile.gif)

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).

[smj]

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...

[Dr Evil]

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.

[smj]

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.

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... (IMG:style_emoticons/default/unsure.gif)

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.

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... (IMG:style_emoticons/default/blink.gif)

[smj]

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.

Thanks, that makes more sense now!

[02loftsmoor]

DRIVER ABUSE (IMG:style_emoticons/default/poke.gif)