Drivetrain clunk...
08-12-2006, 05:38 PM
#1
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Drivetrain clunk... Alright I've hung out in here for quite a while but have never been one of the guys posting their problems. Well until now...there is a first time for everything.
I get a real bad clunk when shifting into 3rd gear, and 3rd gear only. 2nd feels good, and 4th feels good. But 3rd clunks hard and it is throttle dependent. The lighter the throttle the harsher it is. If I am on it more, it isn't as noticeable. At WOT, it is not there at all.
It sounds like it is coming from right under me, and sometimes toward the rear, and it feels bad. It's almost like torque management with a little hesistation right during the shift, but my TM is long gone. Again the clunk/hesitation hits right at the 3rd gear shift. It also seems to be worse when driving in 3 as opposed to D.
It sounds like a "pop" and it can't be good. I haven't gone looking for the problem yet but if anyone can throw some ideas my way it would be appreciated...I really hope it isn't the transmission, being the most expensive thing I have done to the car. I also don't remember it doing this when I put the transmission in the car. It has definetely developed over the past few months.
I get a real bad clunk when shifting into 3rd gear, and 3rd gear only. 2nd feels good, and 4th feels good. But 3rd clunks hard and it is throttle dependent. The lighter the throttle the harsher it is. If I am on it more, it isn't as noticeable. At WOT, it is not there at all.
It sounds like it is coming from right under me, and sometimes toward the rear, and it feels bad. It's almost like torque management with a little hesistation right during the shift, but my TM is long gone. Again the clunk/hesitation hits right at the 3rd gear shift. It also seems to be worse when driving in 3 as opposed to D.
It sounds like a "pop" and it can't be good. I haven't gone looking for the problem yet but if anyone can throw some ideas my way it would be appreciated...I really hope it isn't the transmission, being the most expensive thing I have done to the car. I also don't remember it doing this when I put the transmission in the car. It has definetely developed over the past few months.
08-12-2006, 08:11 PM
#3
I have the same thing - into third only and at very light throttle. It started after the converter and Transgo were installed in my tranny. (I have new u-joints and my mount is good). Here's an old thread with a GM TSB in it claiming it's "normal." https://ls1tech.com/forums/automatic-transmission/223652-2-3-shift-clunk-transgo.html. I talked to a couple of tranny guys and they said it wasn't anything that would cause a problem. But it still bugs me and try to have enough throttle into the shift whenever possible to avoid it.
08-12-2006, 09:46 PM
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Hmm thanks for the info, it doesn't seem "normal" to me because it didn't do it at first. What really bugs me though is the "hit" and the hesitation when it happens. Its quick, but its there. Going into the other gears it slides in and keeps on chugging.
08-13-2006, 01:35 PM
#7
No, because it only happens at lift-throttle or very light throttle. Anything above the most minimal throttle and it doesn't occur. So at that point, I'm either decelerating or maintaining steady speed. Does your tranny have the billet servos? Hopefully Vince @ FLT will post up and offer some insight.
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08-13-2006, 01:47 PM
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My tranny has the Sonnax 2nd gear servo and billet 4th (but will install the sonnax 4th sometime this year, it's in my garage). Only reason it isn't in there now is because the 2nd gear servo was new when I had this built and the 4th wasn't available at the time. Wish someone would have told me about that...oh well.
08-20-2006, 11:51 AM
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I've been thinking more about this and I think it may be related to line pressure. It seems there isn't enough to make a smooth gear change into 3rd at real light throttle, but plenty to shift faster and not "clunk" with more throttle (vac mod), which it does.
Anyone agree? I just hope this isn't going to tear up my tranny just driving it around.
Anyone agree? I just hope this isn't going to tear up my tranny just driving it around.
08-20-2006, 02:14 PM
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And it figures, right after I post this I go for a drive to run some errands, and no where during the 30 mins I was out did it do it today...so what I previously said may not be true.
08-30-2006, 08:44 PM
#11
i have the same problem too...
usually happens between shifts. when it goes to say. 1-2 accelerating mild shifting around 3k it does the "clunk" kind of sound. sort of a loud tap-ish sound. hard to explain it.
but yea. it does it, ne one have any info on this ? it really bugs me and i dont want my tranny to go out. that would make a big hole in the bank account.
usually happens between shifts. when it goes to say. 1-2 accelerating mild shifting around 3k it does the "clunk" kind of sound. sort of a loud tap-ish sound. hard to explain it.
but yea. it does it, ne one have any info on this ? it really bugs me and i dont want my tranny to go out. that would make a big hole in the bank account.
08-31-2006, 10:32 AM
#15
yea, i can hear the bang clunk sound from where i sit. sounds like its coming from the tranny right next to me. its pretty loud sometimes and feels like something just isnt right. if this is "normal" then jez... whats not normal? tranny blowing up?
what to do... what to do...
what to do... what to do...
08-31-2006, 10:57 AM
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I have this "crunch" too, seen people who ought to know saying
it's done to baby one set of components by bring in the beefy
part a bit early (forget the details now) and if you don't clunk it,
you'll maybe break it.
Playing with line pressures is going to modify the phasing of
apply and release some, and having high line pressure at light
loads (like those of us who mess around the force motor table)
may be aggravating the clunkage without any real benefit.
If you -need- a 0.1 second shift cycle at quarter throttle,
OK. But taking out a little and "going Grandma" might be
smoother.
it's done to baby one set of components by bring in the beefy
part a bit early (forget the details now) and if you don't clunk it,
you'll maybe break it.
Playing with line pressures is going to modify the phasing of
apply and release some, and having high line pressure at light
loads (like those of us who mess around the force motor table)
may be aggravating the clunkage without any real benefit.
If you -need- a 0.1 second shift cycle at quarter throttle,
OK. But taking out a little and "going Grandma" might be
smoother.
08-31-2006, 11:29 AM
#17
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my car does it, too. i think maybe in 2nd gear. after i slow down to ~5-10 mph and then tap the pedal very lightly, it'll sometimes bang. it seems common on these cars so i'm not gonna let it eat me alive.
08-31-2006, 06:56 PM
#18
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Originally Posted by jimmyblue
I have this "crunch" too, seen people who ought to know saying
it's done to baby one set of components by bring in the beefy
part a bit early (forget the details now) and if you don't clunk it,
you'll maybe break it.
Playing with line pressures is going to modify the phasing of
apply and release some, and having high line pressure at light
loads (like those of us who mess around the force motor table)
may be aggravating the clunkage without any real benefit.
If you -need- a 0.1 second shift cycle at quarter throttle,
OK. But taking out a little and "going Grandma" might be
smoother.
it's done to baby one set of components by bring in the beefy
part a bit early (forget the details now) and if you don't clunk it,
you'll maybe break it.
Playing with line pressures is going to modify the phasing of
apply and release some, and having high line pressure at light
loads (like those of us who mess around the force motor table)
may be aggravating the clunkage without any real benefit.
If you -need- a 0.1 second shift cycle at quarter throttle,
OK. But taking out a little and "going Grandma" might be
smoother.
Originally Posted by RevGTO
Going back to that old thread I posted up, I'm wondering if lengthening the 2-3 shift time might help. I tuned to shorten all my shift times by 50%.
08-31-2006, 09:28 PM
#19
Originally Posted by jimmyblue
Playing with line pressures is going to modify the phasing of apply and release some, and having high line pressure at light loads (like those of us who mess around the force motor table) may be aggravating the clunkage without any real benefit.