Muskoka

Just did my first, real track session in the turbo. Super fun. The car is so much more planted than other cars I've driven on the track (fist, c63 amg). Went with a few buddies who ranged from complete newbies to a distant connection who had a very successful race career.

I couldn't be happier with the suspension, as I recent upgraded to ohlin road and tracks. The car was really composed on a track which, frankly, isn't in great condition.

However, I did have two concerns:
1) at the end of the day, it got really difficult to get the car into second on heavy braking. I'm assuming this has something to do with my 18 year old motor mounts and tyranny mounts.
2) I could only boost 0.4/0.5 bar. I just replaced the MAf, and I'm still throwing the PASM and ABS lights occasionally (no CEL). So... I have no idea on this one. I've heard it's heat soak going into limp mode. Or a check valve issue. I'll have to boost leak test, but I doubt it. A leak of that size, I think I'd hear at WOT with the windows down.

Anyways, fun day, but wish the car ran strong all day. If anyone has experience with the above, let me know.

Capt. Obvious

I recently replaced the original engine mounts with 964 RS units and upgraded the trans mount to a 997 piece and it made a night and day difference in the shifting and smoothness of my car.

As for the low boost, definitely start with checking for codes and a boost leak test before you start throwing money at things. Those should always be the first things you do when diagnosing an issue with these cars.

theprf

Which track did you run?

Muskoka

Thank you both. I was at Cayuga (Toronto Motorsports Park). It's a low-end track, which is notoriously hard on cars, but it's better than not going to the track.

I agree with the boost leak tester. I will be buying one shortly. It really felt more like a "safe mode" type situation, than anything. But yes, I should have one regardless.

My oil temps were fine, but I'm guessing I overheated the transmission and probably other air temps. I only did ~5 laps at a time, but it definitely got worse closer to the end of the day.

911mhawk

Do the Trans and Motor mounts if they are original, and check your shift cable adjustment.
Put fresh Delvac in the trans if it has been a while.
Add a cooler if you're going to track it regularly, there's a reason the GT cars have them.

Muskoka

Thanks for the advice. Can you let me know what you meant by "check your shifter cable adjustment"? I have swapped shifters a couple times, and I mark exactly where the shift linkage was attached, and keep it identical.

Mike Murphy

I’ve never heard of an overheating manual transmission due to tracking (although some tracks, such as Circuit de la Sarthe have been known to be hard on transmissions due to running at such high speed for so long).

Is the fluid level correct? How old is the fluid?

I believe the clutch mechanism uses the same hydraulic fluid as the braking system. If the fluid wasn’t replaced with high temp premium fluid and you were heating up the system nicely, I would see how this could cause difficulty disengaging the clutch.

Carlo_Carrera

Not sure what events you have attended but in my experience it happens regularly. Most serious track folks increase trans cooling and change their trans fluid at least a couple of times per season because of it.

Turbodan

5 laps at a time would not overheat the trani unless fluid is low IMO.
he was referring to the cable connections at the shifter, they can move around some if not installed correctly. what shifter are you using. fyi I ran at Mosport on Friday and had zero trani issues, 20 min sessions stock trani.
for the boost leak tester you need to build one from parts at home depot. or maybe kevin sells them made already.

Muskoka

I'm using a 997 gt3 kit, but going to do the upgrade to the shift-right solution that all the cup guys talk about.

It's possible that it's a shifter linkage/I stall problem, but sounds more likely that it's from an 18 year old transmission and engine mount(s).

Clutch held strong all day. Not the issue.

I would argue that Cayuga is harder on the car than mosport. Way more hard braking and shifting. Plus, no higher speeds to.cool the car down.

And yes, good point on the transmission heating. If I do the shift right solution plus new mounts, and that still doesn't solve it, it's either a cooling issue or frankly, a driver issue. We'll see.

I just need to do some research on mounts.

Turbodan

I have also done 30 min sessions at Mosport with the 6turbo. I would replace the trani fluid first, as well as the mounts.

Muskoka

Agreed. Mounts and tyranny fluid are a must. I'll be searching for a boost leak tester as well.

My first course of action will be to reset the computer, and see if the boost comes back. If it does, then this is a safe mode issue. If it doesn't, it's a boost leak or something worse. That's my hypothesis anyways.

pfava1

I am having a similar issue of a 'limp mode' while on track myself. I can run fine in my first session, but later in the day, I THINK the trans temps are getting high and putting the car into some kind of safety mode or whatever.
I posted about this a while ago, but never got any good advice. If you look at my charts, around minute 11, I have lost most of my boost, to about .4, which seems like what you are experiencing as well.
https://rennlist.com/forums/996-turb...on-advice.html
Is this what is happening to you?

Mike Murphy

Are there posts on Rennlist that show this?

911mhawk

Porsche's shifters come with a bridge that locks it in place while you adjust the cables, here's a random link I found:
https://rennlist.com/forums/997-foru...1-2-shift.html
Different shifters have different locks too (green/white/blue), so make sure you're using the correct one.
I did the same method as you when I installed and removed the Numeric that came with my car, don't remember if or how far off they were...

My car was acting similar to yours after I tracked it a couple times with 58k on the mounts. After replacing the mounts, fluid and installing a cup shifter it improved for a short while, then went back to being hard to shift.
A couple times on my way home from the track after doing that maintenance I'd have to go into 2nd before I could get 1st to engage at a stop.
Then I started having to put it in 3rd to get it into 2nd to get it into 1st....oh yea, and there was more noise from the trans I noticed on the highway...
If, after doing the mounts, fluid, and adjustment, you experience a similar scenario park your car for the trans rebuild it needs before damage more and have to replace more gears and hard parts vs. just bearings/synchros.
Here's a recent post on a rebuild, and I put up a few back in 2015/16 too, hopefully you don't need to go there yet.
https://rennlist.com/forums/996-turb...questions.html