th350
IMO for a street car how can you give up OD and LOCKUP. Lockup allows you to comfortably use more stall.
The only pro I see to this is maybe slightly better track times with the reduced 1-2 rpm drop BUT that is given the same stall and like I said above with a 4L60E you will be comfortable with more stall because it locks up at cruising speeds.
Someone will say price BUT they will likely be neglecting swap costs. A properly built 4L60E is not cheap, but they can be very reliable. Mine is over 6 years old and built when I thought 400fwhp was a dream I would never achieve, these days the car makes more than that at the tire based on performance. Only change I made to the tranny was redrilling the 1-2 feed hole.
Point being the 4L60E CAN take anything you are looking to throw at it, IF you are willing to use a good builder.
The only pro I see to this is maybe slightly better track times with the reduced 1-2 rpm drop BUT that is given the same stall and like I said above with a 4L60E you will be comfortable with more stall because it locks up at cruising speeds.
Someone will say price BUT they will likely be neglecting swap costs. A properly built 4L60E is not cheap, but they can be very reliable. Mine is over 6 years old and built when I thought 400fwhp was a dream I would never achieve, these days the car makes more than that at the tire based on performance. Only change I made to the tranny was redrilling the 1-2 feed hole.
Point being the 4L60E CAN take anything you are looking to throw at it, IF you are willing to use a good builder.
ya i mean i wont be going to the track really too much.. i do drive the car its an original 6spd car just looking to see how it would be will prob have 3.73's in the future as well. just looking at the 350 for the cost benefit
TECH Regular
Joined: Jun 2009
Posts: 448
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From: new york
a th350 isnt much cheaper to build than a good 4l60 is gonna be ,in a knowledgable tranny guys hands . i had one in my 93 liked it a lot untilllll the days i actually drove the car for a long dist .now in my 94 i have a decantly built 4l60 and prolly wouldnt go back to a th350 again ,if ya want a stronger trans do a th400 and be done with it cause a th350 isnt much better than a 4l60
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Staging Lane
Joined: May 2009
Posts: 81
Likes: 0
My son has a 97 LT1 with the CC503 cam and he took out his 4L60E and put a TH350 in it's place. I think it was a mistake. You loose your overdrive. He had a 4.10 gear in the rearend and it was humming 2500rpm at 40mph. He took out the 4.10 and put a 3.23 and it now hums 2500rpm at 55mph. It hurt his low end power going down in gear, but loosing 2 gears in the switch to the turbo was not the best thing, IMO.
I guess if the car is not your daily driver you can live with it.
I guess if the car is not your daily driver you can live with it.
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12 Second Club
Joined: Feb 2006
Posts: 876
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From: Catlettsburg, Ky
I've swapped in quite a few th350's and replaced quite a few 4L60e's in lt1 cars over the past few years.
I haven't seen a single th350 **** out. but more than half of the 4l60e's have **** out, some of which, the owner decided to go ahead, and swap in a th350 anyways.
with a core, a hardened 2nd gear sprag, and a transgo kit, I've got $500 bucks in my th350. plus $498 bucks for an Edge 3400 converter. modified a stock crossmember, and wired the speed sensor to the rear ABS sensor, and reflashed the computer accordingly.
for just shy of a grand, I've got a tranny/converter that I'd put up against the nastiest "built" 4L60e on the planet.
I haven't seen a single th350 **** out. but more than half of the 4l60e's have **** out, some of which, the owner decided to go ahead, and swap in a th350 anyways.
with a core, a hardened 2nd gear sprag, and a transgo kit, I've got $500 bucks in my th350. plus $498 bucks for an Edge 3400 converter. modified a stock crossmember, and wired the speed sensor to the rear ABS sensor, and reflashed the computer accordingly.
for just shy of a grand, I've got a tranny/converter that I'd put up against the nastiest "built" 4L60e on the planet.
I love my th350 but I think if it was my DD I would get annoyed with it....
i haven't heard much good about the 4l60e unless you dump a pile of money in them....
It is cheaper to do a th350 swap into an F body than to try and build the 4l60 to handle the power.......
i haven't heard much good about the 4l60e unless you dump a pile of money in them....
It is cheaper to do a th350 swap into an F body than to try and build the 4l60 to handle the power.......
The problem with the 4L60E is there are a lot of shops that claim to be able to build them and relatively few that actually can.
mine is from ProBuilt Automatics, the closest thing to a fancy part in it is the vacuum modulator, other than that it is a lot of stock parts with a Transgo, but all the clearances are right and the Transgo setup properly. Stock servo, stock sunshell, stock planetary. The input is NOT sleeved, the output NOT cryo'd, no Kevlar gimmicks, 10-vane pump because that is what belongs in a pump that came 10-vane.
Shifts are positive but NOT harsh, that is important.
When I had him build it I thought my end goal was a ZZ4 cam and some mildly self worked iron heads. Been putting a LOT more than that through it for almost 4 years of the 6 I have had it.
Before that I trusted a local shop, HUGE mistake.
There are 9 second cars running 4L60Es but every kid with a 11-12 second car thinks he needs a 3 speed.
One of the 9 second Impalas, the one with the 434ci Donovan "LT1", ABS AC etc still runs a 4L60E, Rossler built it. That is the single most impressive application of the 4L60E I know of because he is taking 4400lbs or so to up around 160 in the quarter. He has not posted new slips in some time but has posted about rotor cracking issues from 160mph stops. Yes I am sure it was not cheap, but if fully upgraded it is capable of that. The average 4-600fwhp street car really does not need anything too fancy just a competent builder.
mine is from ProBuilt Automatics, the closest thing to a fancy part in it is the vacuum modulator, other than that it is a lot of stock parts with a Transgo, but all the clearances are right and the Transgo setup properly. Stock servo, stock sunshell, stock planetary. The input is NOT sleeved, the output NOT cryo'd, no Kevlar gimmicks, 10-vane pump because that is what belongs in a pump that came 10-vane.
Shifts are positive but NOT harsh, that is important.
When I had him build it I thought my end goal was a ZZ4 cam and some mildly self worked iron heads. Been putting a LOT more than that through it for almost 4 years of the 6 I have had it.
Before that I trusted a local shop, HUGE mistake.
There are 9 second cars running 4L60Es but every kid with a 11-12 second car thinks he needs a 3 speed.
One of the 9 second Impalas, the one with the 434ci Donovan "LT1", ABS AC etc still runs a 4L60E, Rossler built it. That is the single most impressive application of the 4L60E I know of because he is taking 4400lbs or so to up around 160 in the quarter. He has not posted new slips in some time but has posted about rotor cracking issues from 160mph stops. Yes I am sure it was not cheap, but if fully upgraded it is capable of that. The average 4-600fwhp street car really does not need anything too fancy just a competent builder.
It will be like losing OD and lockup on a 4L60E.
Without accounting for non-lockup slip I get about 3000rpms at 60mph assuming a 26" tire.
One more plus for the 4L60E is the DEEP 3.06 first gear, compared to 2.52 for a standard TH350 so you want to launch the same you will need more rearend gear with a TH350.
I will say the closer gearing 1-2 of a TH350 keeps the engine in the powerband better BUT a good converter in a 4L60E goes a long ways towards keeping the engine happy there anyway.
Without accounting for non-lockup slip I get about 3000rpms at 60mph assuming a 26" tire.
One more plus for the 4L60E is the DEEP 3.06 first gear, compared to 2.52 for a standard TH350 so you want to launch the same you will need more rearend gear with a TH350.
I will say the closer gearing 1-2 of a TH350 keeps the engine in the powerband better BUT a good converter in a 4L60E goes a long ways towards keeping the engine happy there anyway.