Does anyone know if the 964 (a '90 C2 Coupe, specifically) has a reverse lock-out built in to the tranny and/or shift mechanism to prevent inadvertanly getting reverse when you are going for 1st?

I did search around a bit on the 'net, and found reference to lock-outs for various Porsche's and trannies, but not the 964 w/G50 tranny.

I have a very good reason for asking.

This past weekend, I had a rather unfortunate incident in my '90 C2 Coupe. During an autocross, while trying for 1st, I seem to have gotten reverse. The gear box appears to have been un-impressed!

The last corner was pretty tight leading into a short straight, and I had gone to 1st on my previous three laps with good results, but I seem to have made a major error, resulting in some very expensive sounding noises.

When I got to me pit space, I tried to select reverse, but it would not go in easily, and even though I was able to jam it into reverse, it was not happy doing so, and popped out of gear when I attempted to back up. The sounds the gear box was making were less than pleasant. I did seem to have forward gears, but optoed not to drive it was whatever broken bits were in the tranny.

The car was towed to my mechanic, but I have yet to get a prognosis, although it's a safe bet something is very broken.

On the bright side, this will allow me to know with certainty if the PO ever updated the flywheel to a LUK, and if not, now's as good a time as any to do it.

But, back to the initial question, if the car does have any sort of lock-out, it appears to not be fool proof (this fool has pretty well proven that!), or perhaps was simply not working properly?

Any information will be appreciated!

Given what this is going to cost to put right, I suspect that from now on I will suffer the consequences of NOT down shifting to 1st on my next autocross!

Best Regards,

Brian Leduc

 

Probably can't really help you, but, my tranny takes extra side pressure to get it into reverse. Don't believe there is any mechanical or electrical lockout to speak of. I've never found that I accidentally could put the car in reverse as it takes some doing to push sideways and up to get it there.

 

Brian, sorry to hear about the unfortunate incident. It raises an issue that came up in a conversation I recently had with our local SCCA autocross course designer. He said that he tries to design the courses so that no one should ever have to down shift b/c he doesn't want anyone to have a mis-shift. The local autocrosses are held in a HUGE open parking lot so he has a lot of flexibility with course design that others may not have.

Hope the prognosis turns out to be fine, or at least not too expensive.

Drew

 

Thank's Drew, but I think the terms "Porsche" and "not too expensive" are mutually exclusive!

The mechanic called, and there are some broken bits relating to reverse. Not sure I recall the parts, but there is some damage.

Truth be known, I did not really have to go to 1st at the finish (I was probably one of the few that did), but it seemed like I was giving up a bit on the very last turn leading into the short straight to the timing lights.

I guess having been running an Integra Type R for 3 seasons makes one think that you ALWAYS need to downshift.

Putting that aside, driving this car on an autocross course was a BLAST. I have never had anywhere near this much power under my right foot.

When I get a chance, I am going to post some comments under my Autocross Set-up thread.

Short Story: Yes, it does push, but it seems to me that this is more to do with applying too much throttle while trying to turn (particularly in slaloms). The front end gets very light when the right foot gets heavy!

FTR, I will be more judicious with the right foot next time. A classic case of "slow down to go fast".

BL

 

This has been a problem. Quite exciting to be at a light, think you are in 1st, and shoot backward! Really not too much of a problem, once you start to drive the car frequently. It would be nice to have a stronger spring for the reverse detent. I have found that if you can train yourself to go to 2ond first, then jam it into 1st, there is no problem.

 

Brian;

I did this with a 914-6 that I use to own in the early 80's, the result was a broken mainshaft, snapped it cleanly in two pieces. I still use that mainshaft as a pilot clutch alignment shaft for every clutch job that I 've done since. It's a sick reminder of a stupid mistake. I bet that you broke the shift fork, if you hit reverse, you would have killed the engine, if that didn't happen you would have broken a shaft. Also, there was a update in '93 for the main shift rod detent & spring (used for adjusting the shift rod). The updated design is a roller ball versus just a rounded steel detent.

Horst nailed it with the perfect shift sequence, If I'm in any gear other that 1st or 2nd, I always put it in to 2nd, then put it home to 1st.

 

I remember when I first learnt to drive (on a VW Bettle beach buggy) I used to try and downshift to first, but there was always some resistance and an unpleasant reaction from the car. In general I was advised that once the car is moving, never to put the car back into first gear. Maybe in the future you could avoid this kind of problem by leaving it in second gear, which usually has enough puklling power anyways.

 

Dear Brian,
The direct answer to your question is No! There is no lock out mechanism and I say with all good humour, join the club. I did this at a Customs border crossing from Austria back into Switzerland. Good job it was late at night and no one was behind me. I felt 2 inches tall. Racing backwards away from the Border guard after he waved me through. The look on his face was something not to be forgotten. I think the look on my face would have been worth seeing as well. Learn by experience. I never understood why Porsche did this but they did. The official answer is the one that Riccardo gave. Use 2nd gear. This is what Porsche told me some time ago. No good when you are stopped on the side of a mountain though, even in a C4,
Ciao,
Adrian
911C4

 

Gee wiz, and I thought I was the only one!

On balance though, I think I would prefer to do this when pulling from a toll booth, rather than in the heat of competition....other than some embarassment, I think doing this at a toll booth would be much less costly!

My mechanic has called, and as expected, noted that the clutch was a bit worn (43,00 miles in the hands of two P.O.s) and it does appear to have a Frudenberg DMF. His suggestions is the Carrera Cup single mass flywheel, and a Cup clutch.

My instinct is to go with a LUK, for two reasons:

1. The various threads talking about idle problems and the like when going to any sort of lightened flywheel. My information on the Cup flywheel indicates that it is 15 pounds lighter than the stock DMF. I may be wrong, but when discussing rotational mass, I would think that 15 pounds is a lot of weight.

2. The desire to remain in compliance with what is considered "Stock" class rules for SCCA autocross. It is permissble to go with the LUK since there is a Porsche factory TSB that permits the update, but not to go with a lightened flywheel, whether or not it is a Porsche piece. And yes, I am exceedingly **** about rules compliance.....probably more so for myself than any competitors.

Thanks again for making me feel like a "member of the club!".

And of course, your comments are welcome.

BL