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The following message was posted on the 993 list here on Rennlist:


"Was talking to a fellow 993 owner --- who with less than 3k mileage had his
transmission rebuilt (under warranty).

Jim said that when his 20 month old 993 had about 3,000 miles on it, he
noticed --- that occassionally it would pop out of 2nd gear --- specifically
when he was using engine braking. When he mentioned it to the dealer ---
they said it was a known problem on '96 993s. Jim then borught it up to
Fred Schwalb at a Parade dinner, and Fred knew about the problem too.

Does anybody know the exact details of what the defective part is/was?"


Does anyone know anything about this alledged problem, is it common knowledge, or just some rare incident?

pbs911

I am very interested in this as well. I am test drving two 96 993 this weekend. Any other symptoms or testing that could be performed to reveal this problem are appreciated.

Robin 993DX

I have only heard of problems gears not disengaging properly, which were caused by rusted input shaft that which prevented the clutch disc from sliding freely.

Weak shift forks are the only weak part that I know of that remotely may go wrong with the 993 transmission.

Haven't heard much about the gear poping out problem.

Jordan Lee

I have noticed a similar symptom in my '96 C2 w/54,000mls. Occasionally under engine braking the transmission will pop out of 2nd gear. Most interested in your findings.
Regards,

MarkC

My <20K mile '95 will occassionally do exactly this.
In fact I can make it do it by using full engine braking with at least 5000revs up, it will sometimes pop out of 2nd gear.
I had the transmission oil changed and it does it even less now but it does still do it.
I am absolutely certain that 2nd is fully home so it has to be a fault.
I'll wait until the clutch needs replacing before investigating the internals of the gearbox but my guess is that it has to be weak detent springs/***** on the 2nd gear dog itself.
I'd be interested to find out if this is a known problem.

Ray Calvo

Haven't heard of any universal problems with the trannies. I'm at 64K miles on a street/track/autocross driven '95 993 and tranny is best of any 911-series I have owned. You sure you don't have engine/tranny mount problems?

I think there is a possibility of the front linkage mount coming loose, but think it's isolated occurrences.

B-Line home

Just a question?

When I was at Skip Barber I brought up the topic of engine braking. Or more specifically Trailing Clutch Oversteer (TCO)

It was my understanding that TCO was a bad thing, not a good thing and you should not use the engine for braking.
Am I misunderstanding something or does that only apply to gearboxes without syncro's??
I ask because I really don't know and would love some clarification on proper engine or no engine braking..
Thanks.

E. J. - 993 Alumni

Definately no engine braking - especially at the track. Our cars have the best engineered and designed brakes of any production car in the world (save a few true exotics). Use them accordingly.

BTW - if you have time to engine brake at the track, you're not going fast enough.

E. J.

Greg Fishman

What EJ said, and brakes are a lot cheaper than clutches in our cars.
Greg

mags993tt-home

Totally agree with EJ and Greg but would add that engine braking occurs naturally when you take pressure off the acclerator - that is good and if you are in the appropriate gear for the circumstances it gives the driver control over the weight distribution in the car be it mid corner, setting up for corner or whatever. That is not to be confused with changing down without matching the engine rpm to the gearbox speed + road speed (by plipping the throttle) which is in essence simply using the clutch plates to slow the car down rather than the brakes which are well up for the job- silly, expensive and possibly quite dangerous in a torquey rear wheel drive like say a Viper as the engine can stop the wheels altogether.

SundayDriver

I agree with all - do not use the engine when you can use the brakes, but...

Throttle application is a very important part of making a car go fast at it's limits. Engine braking and acceleration allow quick, fine tuning of balance as does left foot braking.

MarkC

Back on thread for a moment, is a worn or broken engine/transmission mount easy to see or do you have to remove them to inspect properly?
Also how obvious are the symptoms?
I get a deffinate drivetrain "shunt" coming on and off the power, however I seem to rememebr most of the 993's I test drove (2yrs ago) were similar. I haven't driven another one for a while so I don't have any recent comparisons.

mags993tt

FWIW I get little or no drive train shunt in my 993tt but haven't driven enough 993's to be able to compare - certainly negligible compared to other sports cars I've driven. Slightly off the subject...I test drove an early low mileage (9k miles) 996C4 a while back and couldn't believe how much shunt that car had - crawling along in traffic in first gear with the drive train loaded then depressing the clutch resulted in an extremely audible 'bang' which had me staring in disbelief at the salesman who told me 'they all do that'.

Anthony_Vince

Conversely I owned a '94 993 which had a noticable drive train slack in low gears, however with my current '97 993tt there is no 'shunt'. I figured the 4wd system was tighter and didn't suffer from it, the miles are also lower.

phil@tech9

guys,

with reference to the differences in 'driveline shunt' between a T4 and a C2, the engine and gearbox is mounted differently.

Both models have hyraulic damped rear engine mountings, but the way they are fixed at the gearbox is different.

I am not sure exactly when it was introduced, but on most 993 C2VR and RS and GT2 models that I have seen, they have a pair of braces that secure the gearbox mounting to the chassis.

These braces are fixed onto the bodyshell under the rear seat area. It would be an idea to retrofit these parts, as it would definately help with your problem