Converter Stall with 3.08s and 33" Tires
 

Looking for some advice before I buy a Torque Converter. I have a 72 Blazer with an LQ9, 4l65e, 3.08 gears and 33" tires. I destroyed a pump in my trans and I am replacing the converter as part of the rebuild. Is a higher stall converter a problem with tall gears and large tires? The truck can feel a touch sluggish at times and it's never been tuned.

I know the best plan would be to re-gear to match the overdrive trans and 33" tires, but that's probably not in the cards for now. I may also consider an NV4500 swap down the line that would work better with the current 3.08 gears. So should I put a stock stall converter back in (1600-1800 rpm) or spend a few more bucks for some in the 2600 - 2800 stall range. Stock GM converters are basically around $400 after shipping and core returns. Jumping to a Circle D would be another $200. The I6 trailblazer converter is another option, but I'm not sure how durable that'll be behind the 6.0.

Re: Converter Stall with 3.08s and 33" Tires
 

With 3.08 gears your fighting a uphill battle
The 33s arnt helping either..
Also not having the engine tuned
I'm running a LQ9..having it dyno tuned made it into a beast
I have a nv4500 backed by 4.10s with 31in tires..
As for a tc, I'm out on that, all mine are manual
The other truck I'm working on is a 5.3/nv4500..it has 4.56s and 33 in tires

Bottom line is a od trans and 33s is not ideal with 3.08s
At 55mph your only turning about 1100rpms and at 65mph your turning around 1400
Both the nv and the 4l65 have near identical od gears, so ones no real advantage over the other
If anything, I'd switch to a 4l80..

Re: Converter Stall with 3.08s and 33" Tires
 

you're destroying your pump because the rpms are too low to properly lube the trans with that combo. only proper solution is lower gears. otherwise you'll just burn it up again.

Re: Converter Stall with 3.08s and 33" Tires
 

Never heard anything like that. Lots of GM trucks out there that came stock with a 4l60e and tall gears like a 3.08. The pump is shattering not burning up. Rest of trans looks mint. I’m sure I have a spacing or alignment problem. I didn’t use shims and just eye balled the converter spacing before bolting it up.

The truck drove quite normal and didn’t run at terribly low rpm. Just occasionally got caught a little sluggish at certain downshifts or rpm’s. I’m not a trans expert though, so I’ll have to look into the low rpm/ no lubrication theory.

Re: Converter Stall with 3.08s and 33" Tires
 

its the 33" tires in the mix. the rpms are too low for the 4l60 to lube. had a guy that burned up two trans before he finally dropped the lower gears in to go with the big tires. 4l60 don't like it. 4l80 might.

Re: Converter Stall with 3.08s and 33" Tires
 

The pump on the 4L60 and variants is a variable displacement pump and will deliver whatever pressure/volume is required by the transmission. I owned a 2006 Corvette that would run the same rpms, as given above, and it never had an issue.

You will never have much performance with your gear ratio and tire size.
You said "gear changes are in the cards". I would recommend it "someday" it will make you happy.
Back to the question, a stall in the converter will get your truck moving faster because the motor will be at a rpm where it can make more torque. I would recommend one.

Re: Converter Stall with 3.08s and 33" Tires
 

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I agree with the others. I installed a LS1, 5.7/4l60e combo in my '67 Panel Truck with 3.08 gears. The transmission overheated and blew all of the fluid out the front pump seal. Replaced the 3.08 with a 3.73 and no more problems. Change the gears.....

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