Torque Converter Experts ...
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Team Owner
Joined: Apr 2001
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From: Dallas TX
Torque Converter Experts ...
Ok, so i'm going through my logs trying to figure out why I still have some vibration around 3500rpm.
I am going through some DataMaster transmission logs and I have noticed something very interesting.
First off, my converter is a 2420 stall GM. This is a GM rebuilt and it was just put in a week ago.
With the car in Park, and revving the engine up... starting at 3440 rpm (or around there) the rpm of the engine and the slip rpm of the torque converter are not equal. At 3440rpm, the torque converter is slipping at 3249 rpm, at 3842 engine rpm, the TC is slipping at 3689rpm, and 4363 engine rpm the TC is slipping at 3709rpm, and at 4512 engine rpm the TC is slipping at 4063rpm. So we're talking up to a 500rpm difference between the two here! :eek: :eek:
This doesn't make sense as the car is not moving and neither is anything inside the transmission. So the engine rpm and slip rmp should be exactly the same at all times (when in Park).
Does this suggest something wrong with the converter, and possibly exlplain the vibration i'm getting above 3500rpm!?!?
[Modified by Glock'94, 2:03 AM 3/12/2002]
I am going through some DataMaster transmission logs and I have noticed something very interesting.
First off, my converter is a 2420 stall GM. This is a GM rebuilt and it was just put in a week ago.
With the car in Park, and revving the engine up... starting at 3440 rpm (or around there) the rpm of the engine and the slip rpm of the torque converter are not equal. At 3440rpm, the torque converter is slipping at 3249 rpm, at 3842 engine rpm, the TC is slipping at 3689rpm, and 4363 engine rpm the TC is slipping at 3709rpm, and at 4512 engine rpm the TC is slipping at 4063rpm. So we're talking up to a 500rpm difference between the two here! :eek: :eek:
This doesn't make sense as the car is not moving and neither is anything inside the transmission. So the engine rpm and slip rmp should be exactly the same at all times (when in Park).
Does this suggest something wrong with the converter, and possibly exlplain the vibration i'm getting above 3500rpm!?!?
[Modified by Glock'94, 2:03 AM 3/12/2002]
Drifting
Joined: Oct 1999
Posts: 1,722
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From: Gloucester Va
Re: Torque Converter Experts ... (Glock'94)
Glock,
It seems converter questions are not big topics here. Wish I could answer question but I can't. Maybe this page can help http://www.700R4.com
It seems converter questions are not big topics here. Wish I could answer question but I can't. Maybe this page can help http://www.700R4.com
Thread Starter
Team Owner
Joined: Apr 2001
Posts: 22,267
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From: Dallas TX
Re: Torque Converter Experts ... (88_vette)
Thanks 88_vette ...
I read a lot on there and also did some other searching on the net and found this:
Another Cummins Dodge had an engine vibration, which felt like a minor version of the 6.2 above. This one felt to us like a torque converter vibration and would occur in neutral sitting still but really got the truck to shaking if power was applied from 1500 to 1700 rpm on the road. It was smooth above 1800 rpm. After more than 20 man-hours of frustrating unsuccessful attempts it was discovered that the injector tip washers were the wrong thickness. Fuel was being sprayed in the wrong spot and so would not burn smoothly resulting in the vibration symptom.
Think this could possibly be a reason for my vibration?
[Modified by Glock'94, 2:18 PM 3/12/2002]
I read a lot on there and also did some other searching on the net and found this:
Another Cummins Dodge had an engine vibration, which felt like a minor version of the 6.2 above. This one felt to us like a torque converter vibration and would occur in neutral sitting still but really got the truck to shaking if power was applied from 1500 to 1700 rpm on the road. It was smooth above 1800 rpm. After more than 20 man-hours of frustrating unsuccessful attempts it was discovered that the injector tip washers were the wrong thickness. Fuel was being sprayed in the wrong spot and so would not burn smoothly resulting in the vibration symptom.
Think this could possibly be a reason for my vibration?
[Modified by Glock'94, 2:18 PM 3/12/2002]
Drifting
Joined: Feb 2002
Posts: 1,937
Likes: 2
From: Arvada CO
Re: Torque Converter Experts ... (Glock'94)
Well this seems like the same problem my friend had with his converter??? We busted our Asses getting the tranny out and it was rebuilt by the local shop and he went with a 2500 stall and we got it back in and it stalls and it vibrates and so he was like "something is not right?" So we ripped it out again...and we sent the converter back and come to find out the converter was bad and it was not balanced? So after 2 weeks waiting for a new converter we installed it and it drives like a dream! when he stalls it out to 2499 it locks up and launches so hard it makes me :U But i am no expert but that sounds like a bad converter to me..? But what do i know :D
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From: Dallas TX
Re: Torque Converter Experts ... (krivera)
Yeah, sounds like a bad converter to me too. But it's kind of odd that it has the vibration at the same rpm that it did before :bb :bb . My mechanic better not have lied to me and put my old one back in!!
I'm taking the car back down there again today and we're putting it on the lift and going to unbolt the converter to see if it still vibrates... if it does then we know it's not the converter and it's something to do with the engine.
I'm taking the car back down there again today and we're putting it on the lift and going to unbolt the converter to see if it still vibrates... if it does then we know it's not the converter and it's something to do with the engine.
Drifting
Joined: Oct 1999
Posts: 1,722
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From: Gloucester Va
Re: Torque Converter Experts ... (krivera)
What I want to know is how you are in the car and know that your converter is turning at a different rate? Did I miss something?
How about your drive shaft? I know you did u-joints not to long ago. Not sure if you said it vibs only under load or not?
Have you unbolted the converter to see if it's possible it's the engine?
How about your drive shaft? I know you did u-joints not to long ago. Not sure if you said it vibs only under load or not?
Have you unbolted the converter to see if it's possible it's the engine?
Burning Brakes
Joined: Nov 2001
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From: Houston TX
Re: Torque Converter Experts ... (Glock'94)
note that the truck in question is a direct-injection diesel. (hmmm, maybe not direct-injection, but it's likely.)
with an efi system on a gasoline auto, the engine couldn't give a hoot where the injector is spraying. different manifolds for different chassis that use the same engine often have different injector locations. with sequential systems, you can even deliberately connect the wrong harnesses to the injectors, and there's no subjective difference in how the car runs.
on unbolting the converter: how will this decouple it? if the converter is sized properly, you shouldn't be able to move the converter studs completely clear of the flexplate. or, does yours use bolts?
with an efi system on a gasoline auto, the engine couldn't give a hoot where the injector is spraying. different manifolds for different chassis that use the same engine often have different injector locations. with sequential systems, you can even deliberately connect the wrong harnesses to the injectors, and there's no subjective difference in how the car runs.
on unbolting the converter: how will this decouple it? if the converter is sized properly, you shouldn't be able to move the converter studs completely clear of the flexplate. or, does yours use bolts?
Thread Starter
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Joined: Apr 2001
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From: Dallas TX
Re: Torque Converter Experts ... (88_vette)
What I want to know is how you are in the car and know that your converter is turning at a different rate? Did I miss something?
How about your drive shaft? I know you did u-joints not to long ago. Not sure if you said it vibs only under load or not?
Have you unbolted the converter to see if it's possible it's the engine?
How about your drive shaft? I know you did u-joints not to long ago. Not sure if you said it vibs only under load or not?
Have you unbolted the converter to see if it's possible it's the engine?
It's not anything farther back than the torque converter because it does it in Park and Neutral.
I haven't unbolted the torque converter yet, I'm waiting until I can get it on a lift to do that ... much easier than jacking it up really high.
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Thread Starter
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Joined: Apr 2001
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From: Dallas TX
Re: Torque Converter Experts ... (MSR)
note that the truck in question is a direct-injection diesel. (hmmm, maybe not direct-injection, but it's likely.)
with an efi system on a gasoline auto, the engine couldn't give a hoot where the injector is spraying. different manifolds for different chassis that use the same engine often have different injector locations. with sequential systems, you can even deliberately connect the wrong harnesses to the injectors, and there's no subjective difference in how the car runs.
on unbolting the converter: how will this decouple it? if the converter is sized properly, you shouldn't be able to move the converter studs completely clear of the flexplate. or, does yours use bolts?
with an efi system on a gasoline auto, the engine couldn't give a hoot where the injector is spraying. different manifolds for different chassis that use the same engine often have different injector locations. with sequential systems, you can even deliberately connect the wrong harnesses to the injectors, and there's no subjective difference in how the car runs.
on unbolting the converter: how will this decouple it? if the converter is sized properly, you shouldn't be able to move the converter studs completely clear of the flexplate. or, does yours use bolts?
Yes, all converters that I have seen use bolts.
Le Mans Master
Joined: Apr 2000
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From: Manassas VA
Re: Torque Converter Experts ... (Glock'94)
IMO (uneducated I add) I would think that the difference could be caused by 2 different possibilities. 1.the sensors that detect the RPM not being 100% accurate. 2. Could it be that this is where a converter efficiency rating comes into play. IE: 94% efficient?
Drifting
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From: Big D Tx
Cruise-In II Veteran
Re: Torque Converter Experts ... (Red 86 4+3)
your tq speed wont ever equal your engine rpm in park or neutral, only during lockup. slippage is normal. how does your harmonic balancer look.
Thread Starter
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From: Dallas TX
Re: Torque Converter Experts ... (88L98)
your tq speed wont ever equal your engine rpm in park or neutral, only during lockup. slippage is normal. how does your harmonic balancer look.
I watched the harmonic balancer as I reved it over 3k and it looks fine. It doesn't appear to be shaking, though 3k+ rpm is hard for the eyes to see small things like that.
[Modified by Glock'94, 2:05 PM 3/14/2002]
Le Mans Master
Joined: Apr 2000
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From: Manassas VA
Re: Torque Converter Experts ... (Glock'94)
your tq speed wont ever equal your engine rpm in park or neutral, only during lockup. slippage is normal. how does your harmonic balancer look.
hmm.. ok. I guess that makes sense considering that if the tc locked up like it's supposed to ver 2400rpm then the transmission would be engauged and the car would take off :)... I guess I should get a log of transmission data going through the vibration range while driving.
I watched the harmonic balancer as I reved it over 3k and it looks fine. It doesn't appear to be shaking, though 3k+ rpm is hard for the eyes to see small things like that.
Hey Glock,
2 more things. First lock up and stall are 2 different things. Lock up only happens above a set speed and at cruise etc. On checking the harmonic balancer for shaking, I wonder if you used a timing light and shined it on the balancer if you would be able to see it shake? I know in commercial HVAC they will use an adjustable strobe light to look for viberations.
[Modified by Glock'94, 2:05 PM 3/14/2002]
hmm.. ok. I guess that makes sense considering that if the tc locked up like it's supposed to ver 2400rpm then the transmission would be engauged and the car would take off :)... I guess I should get a log of transmission data going through the vibration range while driving.
I watched the harmonic balancer as I reved it over 3k and it looks fine. It doesn't appear to be shaking, though 3k+ rpm is hard for the eyes to see small things like that.
Hey Glock,
2 more things. First lock up and stall are 2 different things. Lock up only happens above a set speed and at cruise etc. On checking the harmonic balancer for shaking, I wonder if you used a timing light and shined it on the balancer if you would be able to see it shake? I know in commercial HVAC they will use an adjustable strobe light to look for viberations.
[Modified by Glock'94, 2:05 PM 3/14/2002]
Thread Starter
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From: Dallas TX
Re: Torque Converter Experts ... (Red 86 4+3)
Ok, here's the news... just got back from having it on the lift. With the torque converter unbolted, it was still making the vibration.
I think (according to 2 people), this is good. It is the engine doing it, and after bolting the torque converter back on my mechanic did a lot of feeling while it was in vibration range and he says that it isn't the balance of the engine. It could only be the harmonic balancer, flexplate, or TIMING! So I'm back to what FriskyZ06 said .. it's probably a timing issue.
Thanks for all the help guys! Now I just need to get my flash chips reburned so I can upload a new timing table.
I think (according to 2 people), this is good. It is the engine doing it, and after bolting the torque converter back on my mechanic did a lot of feeling while it was in vibration range and he says that it isn't the balance of the engine. It could only be the harmonic balancer, flexplate, or TIMING! So I'm back to what FriskyZ06 said .. it's probably a timing issue.
Thanks for all the help guys! Now I just need to get my flash chips reburned so I can upload a new timing table.
