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Dead at the track

11K views 95 replies 12 participants last post by  Alan Arnesen 
#1 ·
My car is stuck in gear at the track. The SMG started freaking out and then the car stopped. Tried a couple of ignition cycles with no change. Waiting for a tow truck.
Any ideas while I'm waiting? Did not bring the laptop.
 
#31 ·
Yes a clean up, plenty of brush left.

So I took the car for a spin with INPA running. One thing I noticed right away was that the cycling pressure bumped up. It started at 62bar and when up to almost 80bar with the temp at 20c. By the time my drive was over it was 62bar up to 90bar at 85c. The pressure would bleed off much fast of course but I had no faults on my 40min drive.

I think it's just a bunch of old worn out o-rings. I will change the tune and recheck the pressures. I would not put it by some capitalist to soften the faults to keep a car out of the shop. With that done I will throw and accumulator at it mostly just for the hell of it and because it's easy. After that will be a full control system replacement or rebuild. As far as I know it's 14 years old and has 117k on it.

One last thing I may try is a different fluid or some type of additive. My Dad used to do it all the time on old automatics with good results. If I am going to overhaul the system I don't really have anything to loose.
 
#33 ·
I did not scrape the stampings. You don't miss much do you?

Based on my observations the pump is running as it should. I of course could observe it for longer but I think the pressure drop and cycling frequency is high, less than 30 seconds with the oil hot, car running and parked with no commands. The saga will continue with systematic replacement of parts at an ever increasing cost until I'm satisfied that the problem is resolved.

Before I committed to this platform I accepted that one day this would happen and I'm prepared and committed to fix it. That's half the fun.
 
#34 ·
Lol... In my old motor it was the stampings causing the brushes to get stuck in their holder. The refurb motor diy post showed the same thing. Either yours is the exception or you'll fix them soon haha...

One observation I had when I installed a new motor is that new brushes slid freely through the stamped section. I suspect the stampings weaken the brushes, somehow causing them to bulge in that area given time and spring pressure. Just a crazy theory based on what I saw...
 
#39 ·
Well here's what I discovered, take or leave it.
I put the US SMG tune back in. I noticed right away that the cycle pressures are lower. I started with oil at 17c and it took 2.5 minutes for it to cycle with the engine off. With the engine on it did not change. The big difference is that the pressures were 43 and 65 bar. When I last checked the Euro tune in neutral with the engine running it was 78-90bar. Higher pressure, more leak-by, more heat.

I had my son watch the cycle pressures as I drove in 5th gear at part throttle. Each increase in shift mode had a corresponding increase in pressures. The first two bars were 43-65, the next two bars were 45-75 and the last two were 58-80bar. So being in S6 definitely would increase the pressure literally and even more so with the Euro tune. The DSC had no effect on the pressures, P500 had no effect on pressures. The sprint booster does have an effect but maybe not the way you would think. The booster amplifies the signal from the throttle so if you have a soft foot the car will still drive like a raped ape. The effect that this has is that the SMG monitors the pedal position and torque values of the engine. If you put your foot into it, the pressures will increase as the car is expecting a shift at high load. I directly observed this.

So for me the Euro tune is out. A 4000rpm launch is not on my list of things to do all the time. I have no idea what the timeout period is for the HPU but I have emailed Jim about a delete. There is no doubt that my SMG is old but for now to spare me a $3000 bill and a tranny pull I'm backing off. I'm going to try and get on the track Thursday and see if I am full of $hit or not. An oil upgrade and maybe an additive are on the list. I think the pump, motor and rely are fine. Tomorrow I will be looking into a way to get some cool air to the HPU to bring the temps down. 75c at the end of the drive today and 85c at the end of the last drive with the Euro tune.

If you are having HPU fault codes consider dumping the Euro tune if you have it to lower the pressures. Make sure the oil is fresh and the relay and motor are good to go. Short of that you will need to get the control unit rebuilt or replaced. And don't for get the slave cylinder. The SMG is great for it's vintage and the motor is awesome of course.
 
#42 ·
I was watching the temp, rise of course. As I went through each setting I would allow it to cycle a few times to confirm the pressures. When I got home in the driveway with hot oil the pressures were the same as when I started for a given setting.

If you have a map of settings to look at that would be interesting to compare with my observations. If the pressure sensor were bias that would effect the system. When I did a bleed down it did drop to 1.5bar which is pretty close considering the range.
 
#44 ·
I have not seen that. It's way above my level of programming. It seems like they were just doing it to do it no real reason that I could see?

I took a closer look at the cooling and there are already two ports in the under-body to feed air to both sides of the transmission. Some of the heat shielding for the exhaust was bent and obstructed the air flow, I corrected that.

I went for another drive yesterday, INPA running in the passenger seat. More bars more pressure, S6 cycling is frequent. It was a causal drive and cool with some rain. Temp was up to 83c at the end of the drive and the cycle time in S4 was 15sec. Has anyone else watched there pressures and temperatures on the SMG?
 
#49 ·
So I made it to the track today. The short story is the transmission faulted again. S3 the whole time.
Now the long story,
I arrived at 1100 but did not go on the track until 1220 so the car had time to cool off. I have had no faults on the street since going back to the US SMG tune. I went out for about 20 minutes with no problems. I came in to check an set the tire pressures with the car running. As soon as I got 1/2 lap back on the track the trans faulted.
I drove off the track at about 1pm and let the car cool off until 2:20. Went out with the temp at 80c and ran 20 minutes just fine(temp at 104c). Let the car cool off for about 20 minutes and headed back out for the final run. Got about 15 minutes in and got another trans fault.
I was pretty happy with my time on the track and called it a day. The next order of business is going to be the accumulator and clutch solenoid.
 
#50 ·
This will wrap up this thread for me.

I got inspired to dig into the HPU before going to the track today. I ordered o-rings for the clutch solenoid and pump, rebuilt accumulator, pressure and temp sensors and of course fresh oil. I did all the work with the trans and exhaust in place, I would not recommended it. Inspecting the o-rings on the clutch solenoid they had small frayed edges, this was observed under a powerful magnifying glass. The accumulator, pump o-rings and sensors were done just because I was there I do not believe they were necessary. Here is a video of the inside of the pump, nothing special just keep it in order if you rebuild it. I had no trouble bleeding and testing after the work.



So the pump cycling is significantly less, 5 minutes at 24c in neutral. The big change was after the test drive, 2 minutes at 87c. Before the times were 2 minutes at 17c and 15 seconds at 80c. I think the solenoid o-rings made the difference. When I did the motor I should have done the solenoid o-rings at the same time. As our SMG's age this will be and ongoing issue. I think step one is the motor, pump, clutch solenoid, accumulator and sensors. Step two is the valve body and wiring which will come this winter. As for the oil based on my research stay with factory oil. There are other options but none with a viscosity index anywhere near factory. In other words to get a higher hot viscosity you would have to use a very high cold viscosity. I left the skid plate off to see if the SMG stays cooler, based on the test drive I doubt it.

As for the Euro SMG tune and the shift settings. The tune will stay out, it definitely caused more problems. The shift settings will stay at S3. This lowers the pressures, if you want quick shifts the engine torque calculations will make the SMG shift hard. Back to the track thread after today.
 
#52 ·
As long as it is still a fluid, it will still transmit pressure and operate the valves. What could happen with very hot fluid is that it bypasses/leaks more because the orings become more malleable and it they are torn more fluid bypasses. I've seen my orings torn on the outer edges when I replaced them, seems to be the same as what Alan and others have mentioned, it doesn't really show up in a photo. I'm in the process of refurbing mine, but making little progress as it's too hot and humid to be doing much wrenching. Not looking forward to getting the trans mounted back in the car.

Viscosity of the oil effects the pumpability, but that doesn't seem to be the issue you are dealing with.
 
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