Trailblazer torque converter

[iamdub]

I'll be pulling my engine when I do the AFM delete so I'll have full access to the torque converter. I've seen plenty of talk about the torque converter from an I6 Trailblazer being a nice budget upgrade in GMT800 trucks but I didn't find anything about it being in a GMT900 SUV. I'm sure my '08 4L60E (or 4L65E?) is the same in that sense as the previous generations.

Before I get the third degree, I'm researching this for a few reasons. One, I may have a balance problem with my stock converter and, two, I wouldn't mind a few hundred extra RPM at launch.

The balance problem: I have what feels like a rhythmic shaking that starts out around 1600ish RPM, is strongest at what looks to be 1750 RPM, and seems to smooth out by 1900ish RPM. It all comes back and acts just the same, along the same RPM range, at exactly twice the RPM of the original shaking with the strongest at 3500 RPM. It does it when revving up and down and isn't noticeable when revving quickly. The engine doesn't shake like a dead cylinder and it's mostly only felt in the seat. If I jab the throttle to quickly rev to 1750 and hold it there, the shaking feels like it comes on rather quickly, but it's not instant like a dead or weak cylinder. The way it seems to be RPM-related and happening at RPMs that are even multiples of each other, it really feels like it's an imbalance issue. I've never felt an imbalanced crank pulley so I can't rule that out. But it feels "heavy". All things considered, my thoughts are led to the torque converter. The problem with that hypothesis is that I don't believe it's there while driving. I may just not be feeling it, though.

I'm mainly seeing what you guys think so I can be prepared for when the engine is out.

 

[iamdub]

Another stumper, huh?

A new crank pulley is about $50, so I'll probably order one of those as a preventative measure since it'll be off anyway.

 

[wjburken]

Another stumper, huh?

A new crank pulley is about $50, so I'll probably order one of those as a preventative measure since it'll be off anyway.

Your post got me curious as I had never heard of torque converter balance issues, but hey, it’s a rotating mass so it makes sense. I now know they sell weights for torque converters like wheels.

Came across this thread on another forum about seeing if there is a balance issue. Not sure if it directly applies to your situation and if you’ve already seen this, I apologize.
http://nastyz28.com/threads/what-would-an-out-of-balance-torque-converter-do.20372/

 

[iamdub]

Your post got me curious as I had never heard of torque converter balance issues, but hey, it’s a rotating mass so it makes sense. I now know they sell weights for torque converters like wheels.

Came across this thread on another forum about seeing if there is a balance issue. Not sure if it directly applies to your situation and if you’ve already seen this, I apologize.
http://nastyz28.com/threads/what-would-an-out-of-balance-torque-converter-do.20372/

No need to apologize and I'm open to any suggestions! As much as I'd like to have all my parts beforehand, I'll probably have this project stretched out over two weekends of not more. So, if I need to order a converter, it shouldn't be a big deal. That's a good idea: I'll unbolt the converter from the flywheel before I remove anything else so I can start it and see if the shakes remain. Thanks for the help!

 

[pwtr02ss]

I'll be pulling my engine when I do the AFM delete so I'll have full access to the torque converter. I've seen plenty of talk about the torque converter from an I6 Trailblazer being a nice budget upgrade in GMT800 trucks but I didn't find anything about it being in a GMT900 SUV. I'm sure my '08 4L60E (or 4L65E?) is the same in that sense as the previous generations.

Before I get the third degree, I'm researching this for a few reasons. One, I may have a balance problem with my stock converter and, two, I wouldn't mind a few hundred extra RPM at launch.

The balance problem: I have what feels like a rhythmic shaking that starts out around 1600ish RPM, is strongest at what looks to be 1750 RPM, and seems to smooth out by 1900ish RPM. It all comes back and acts just the same, along the same RPM range, at exactly twice the RPM of the original shaking with the strongest at 3500 RPM. It does it when revving up and down and isn't noticeable when revving quickly. The engine doesn't shake like a dead cylinder and it's mostly only felt in the seat. If I jab the throttle to quickly rev to 1750 and hold it there, the shaking feels like it comes on rather quickly, but it's not instant like a dead or weak cylinder. The way it seems to be RPM-related and happening at RPMs that are even multiples of each other, it really feels like it's an imbalance issue. I've never felt an imbalanced crank pulley so I can't rule that out. But it feels "heavy". All things considered, my thoughts are led to the torque converter. The problem with that hypothesis is that I don't believe it's there while driving. I may just not be feeling it, though.

I'm mainly seeing what you guys think so I can be prepared for when the engine is out.

I don't visit this section often so I'm a little late.

Yes, the V6 TB torque converter should work without any issues. Your truck "should" have the 4L65E, basically the same thing but 5 pinion planetary gear and hardened input shift. We did that swap to my buddies SSS when we rebuilt the trans.

In my honest opinion, I don't care for the way it feels. It feels a little too sloppy for the amount of stall you're getting. If and when I do anything to my avalanche, I'll probably buy a small pro yank and be done. I really like the way the one in my camaro feels.

As for the vibration, you could very well have your answer with the crank pulley. That rubber wears out over time and its possible that it has slipped.

Are you going to rebuild your trans yourself or have someone do it?

 

[iamdub]

I don't visit this section often so I'm a little late.

Yes, the V6 TB torque converter should work without any issues. Your truck "should" have the 4L65E, basically the same thing but 5 pinion planetary gear and hardened input shift. We did that swap to my buddies SSS when we rebuilt the trans.

In my honest opinion, I don't care for the way it feels. It feels a little too sloppy for the amount of stall you're getting. If and when I do anything to my avalanche, I'll probably buy a small pro yank and be done. I really like the way the one in my camaro feels.

As for the vibration, you could very well have your answer with the crank pulley. That rubber wears out over time and its possible that it has slipped.

Are you going to rebuild your trans yourself or have someone do it?

*I-6

I kinda studied the numbers a little more lately and think a stall of ~1,000 RPM higher than stock on a stock motor is a hair on the loose side for me. I should probably stick to a 2,000 and no higher. I think I'll just go with the crank pulley for now since it's cheap and probably the more likely culprit.

I don't rebuild transmission, so I'll get a built one when that time comes. I'd love to do a 6L80 conversion, but not if I can't make it operate 100% like stock with the Tapshift and correct gauge cluster. I'm actually toying with the idea of an NV3500 HD. It's "only" a 5-speed, but it's more than 4, has nice ratios and it's a manual.

 

[pwtr02ss]

*I-6

I kinda studied the numbers a little more lately and think a stall of ~1,000 RPM higher than stock on a stock motor is a hair on the loose side for me. I should probably stick to a 2,000 and no higher. I think I'll just go with the crank pulley for now since it's cheap and probably the more likely culprit.

I don't rebuild transmission, so I'll get a built one when that time comes. I'd love to do a 6L80 conversion, but not if I can't make it operate 100% like stock with the Tapshift and correct gauge cluster. I'm actually toying with the idea of an NV3500 HD. It's "only" a 5-speed, but it's more than 4, has nice ratios and it's a manual.

Ah, I forgot about the new fangled inline motors.

I had never rebuilt a transmission either but I have 3 under my belt now. I have some really good information so if and when the time comes, hit me up. From what I've seen, you're far more than capable. 6 Speed would be a nice upgrade for sure. Best of luck in whatever path you take.

 

[Ilikemtb999]

Any balancer I’ve seen that’s failing you can visually see wobble. It was a big thing with g8’s and they sure were wobbly. Good idea to start there.


As far as a converter goes, what cam are you tossing in?

 

[Ilikemtb999]

Circle D makes a stock size converter for the 4l60 that they suggest for SUV’s and trucks. It also comes in lower stalls than most “performance” converters. It would probably not be a bad idea to contact them with what you’re looking for and what other mods you’ll have and see what they suggest.
https://www.circledspecialties.com/4l60-hp-series-300mm

 

[iamdub]

Any balancer I’ve seen that’s failing you can visually see wobble. It was a big thing with g8’s and they sure were wobbly. Good idea to start there.


As far as a converter goes, what cam are you tossing in?

I never knew it was a common issue, but I've never had a reason to investigate. I'm glad to hear that it's a possibility with a simple and cheap solution. I plan to have someone work the throttle while I watch the pulley.

Stock L33 cam. Same specs as my original AFM cam, but without the AFM lobes. Yes, it IS painful for me to go this deep and keep it stock. Please don't chastise me as I'm still working through this. It's a logical need-versus-want decision.