Automatic transmission not engage
#376
Rennlist Member
#377
Racer
Thread Starter
Both !!!
Our analysis:
1 - (Big) Shock on the pan with hot ATF. This shock was not here when we changed ATF some weeks before.
2 - Dust / debris in free hot AFT flow
3 - When cold, dust and debris stuck in the valve body
Our analysis:
1 - (Big) Shock on the pan with hot ATF. This shock was not here when we changed ATF some weeks before.
2 - Dust / debris in free hot AFT flow
3 - When cold, dust and debris stuck in the valve body
#379
Racer
Thread Starter
#380
Rennlist Member
That doesnt make sense. A 'driver' isnt going to break these transmissions.
When you break it..with over 1000Hp, then you can say "it just broke".
Last edited by Speedtoys; 08-23-2021 at 02:03 AM.
#381
Racer
Thread Starter
#383
Rennlist Member
I have suspected the dink in the pan as being relevant ever since you introduced it but the notion that it caused debris to enter the system would trouble me some.
I would think it is quite possible that some debris collects in the bottom of the pan and maybe that was disturbed by the "event" but how would such get past the filter unless the filter element was somehow distorted in the process and one presumes you would have spotted such?
As I understand the oil sits in the sump and is sucked into the filter that is normally flooded- presumably why it has a large footprint- and nothing should get past that element. For sure once that system is compromised and crap were to get in there, it would not take much to cause the problem you experienced. There is a lot to be said for ensuring one knows the real cause of such an event if for no other reason to learn from it.
That being said it takes quite some effort to dink the tranny pan [given the way it is somewhat recessed] or so I would think and if one did I am pretty sure one would know all about it. I have never read of such happening previously but as with most things in life there is always a first time!
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Fabien92 (08-23-2021)
#384
Racer
Thread Starter
It was also the first time that a transmission was fully down !! I will never be sure about the root cause of my failure. I just try to understand a scenario
BTW, we will check and plug the vacuum line on next saturday. I hope it's the end !!
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Schocki (08-24-2021)
#385
Racer
Thread Starter
Well done ! 😃
The vacuum line was disconnected after the steel hose.
All upshifts change smoothly right now 😃👌
Now more slipping, just between 2400 and 2500 RPM. I will adujst it when I will receive my new modulation valve.
Today I am a new happy 928 driver 😊
The vacuum line was disconnected after the steel hose.
All upshifts change smoothly right now 😃👌
Now more slipping, just between 2400 and 2500 RPM. I will adujst it when I will receive my new modulation valve.
Today I am a new happy 928 driver 😊
#386
Rennlist Member
The car should shift like never before now. Especially when warm it should be very smooth.
Keeping my fingers crossed that a new modulator valve will do the trick.
Good to hear that I was not that far off with my vacuum line disconnect.
Keeping my fingers crossed that a new modulator valve will do the trick.
Good to hear that I was not that far off with my vacuum line disconnect.
Last edited by Schocki; 08-28-2021 at 03:06 PM.
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Fabien92 (08-28-2021)
#387
Racer
Thread Starter
I have a new transmission rebuild at 98% right now 😊 I hope to be soon at 100% with the new modulation valve.
The first 100 km since 8 months are very good 😊 So happy !!
Last edited by Fabien92; 08-28-2021 at 09:42 PM.
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Fabien92 (08-29-2021)
#389
Racer
Thread Starter
One last question
About B2 piston, I don't know if my B2 brake band clearance is good. Is it possible to try a longer pin without to remove the pan and to measure the B2 brake band clearance ?
Ie. If I have the pin of 48.0 mm, can I try the next pin of 48.8 mm ? All sizes are 47.2 mm, 48.0 mm, 48.8 mm, 49.6 mm.
About B2 piston, I don't know if my B2 brake band clearance is good. Is it possible to try a longer pin without to remove the pan and to measure the B2 brake band clearance ?
Ie. If I have the pin of 48.0 mm, can I try the next pin of 48.8 mm ? All sizes are 47.2 mm, 48.0 mm, 48.8 mm, 49.6 mm.
Last edited by Fabien92; 08-30-2021 at 01:30 AM.
#390
Rennlist Member
It should be possible but I'll leave the answer to our tranny expert GB.
I don't think, that a longer pin will do the trick. AFAIK B2 is activated in all forward gears, if B2 fails you can only drive backwards.
I don't think, that a longer pin will do the trick. AFAIK B2 is activated in all forward gears, if B2 fails you can only drive backwards.
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Fabien92 (08-30-2021)