Making the switch
02-19-2015, 06:59 PM
#1
Making the switch After over 250 passes on my stock 4l60e with Yank 4000 SS converter I am making the switch to a Th 350 with 8" converter. The stock trans has been good to me but it is time for the change for reliability reasons. The car is raced every week and I need it to stay together. Anyone care to guess if I will see any performance gains. So far best et 11.502 at 1.50 60'. Be told .2 to .3. I sure hope so.
02-19-2015, 08:04 PM
#2
Moderator
Let me just take a wild guess...
Assuming you were getting good traction off the line, the change from a 3.06 to a 2.52 will cost you a slower 60'. The tighter 1-2 shift ratio and slightly lower parasitic friction loss will gain that back and improve your ET by 0.05 seconds.
However if your new converter is better matched to your engine torque curve and rear end ratio, you might see a 0.2 ET improvement from the converter.
Hey it's just an uneducated guess; I'm eager to learn what it really turns out to be.
Why not go with a TH400? Or did you get a good deal on the TH350 and converter?
Assuming you were getting good traction off the line, the change from a 3.06 to a 2.52 will cost you a slower 60'. The tighter 1-2 shift ratio and slightly lower parasitic friction loss will gain that back and improve your ET by 0.05 seconds.
However if your new converter is better matched to your engine torque curve and rear end ratio, you might see a 0.2 ET improvement from the converter.
Hey it's just an uneducated guess; I'm eager to learn what it really turns out to be.
Why not go with a TH400? Or did you get a good deal on the TH350 and converter?
02-19-2015, 08:48 PM
#3
Let me just take a wild guess...
Assuming you were getting good traction off the line, the change from a 3.06 to a 2.52 will cost you a slower 60'. The tighter 1-2 shift ratio and slightly lower parasitic friction loss will gain that back and improve your ET by 0.05 seconds.
However if your new converter is better matched to your engine torque curve and rear end ratio, you might see a 0.2 ET improvement from the converter.
Hey it's just an uneducated guess; I'm eager to learn what it really turns out to be.
Why not go with a TH400? Or did you get a good deal on the TH350 and converter?
Assuming you were getting good traction off the line, the change from a 3.06 to a 2.52 will cost you a slower 60'. The tighter 1-2 shift ratio and slightly lower parasitic friction loss will gain that back and improve your ET by 0.05 seconds.
However if your new converter is better matched to your engine torque curve and rear end ratio, you might see a 0.2 ET improvement from the converter.
Hey it's just an uneducated guess; I'm eager to learn what it really turns out to be.
Why not go with a TH400? Or did you get a good deal on the TH350 and converter?
02-20-2015, 04:04 AM
#4
Let me just take a wild guess...
Assuming you were getting good traction off the line, the change from a 3.06 to a 2.52 will cost you a slower 60'. The tighter 1-2 shift ratio and slightly lower parasitic friction loss will gain that back and improve your ET by 0.05 seconds.
However if your new converter is better matched to your engine torque curve and rear end ratio, you might see a 0.2 ET improvement from the converter.
Hey it's just an uneducated guess; I'm eager to learn what it really turns out to be.
Why not go with a TH400? Or did you get a good deal on the TH350 and converter?
Assuming you were getting good traction off the line, the change from a 3.06 to a 2.52 will cost you a slower 60'. The tighter 1-2 shift ratio and slightly lower parasitic friction loss will gain that back and improve your ET by 0.05 seconds.
However if your new converter is better matched to your engine torque curve and rear end ratio, you might see a 0.2 ET improvement from the converter.
Hey it's just an uneducated guess; I'm eager to learn what it really turns out to be.
Why not go with a TH400? Or did you get a good deal on the TH350 and converter?
02-20-2015, 06:42 AM
#5
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I am in the same position. Do I do a 350 swap loose the first gear in the 4L60 and the overdrive for cruising. Or buy a Bad *** 4L60? I priced out a good th350 and all the swap parts and was way over $2000. RPM level 6 trans $3000 shipped.........
02-20-2015, 07:36 AM
#6
Moderator
Hopefully some people that have actual experience hop on here, but spending over $2000 for a race-built TH350 sounds crazy (to me) when a relatively plain rebuilt TH400 would likely be more durable.
FASHOOTER: Since you want to cruise, get the premium 4L60E from RPM or FLT. Get whatever level has the Sonnax Smart Tech input drum so that it has the most durables 3/4 clutch possible.
I have no experience here, just keeping the tread going until some experts hop in.
FASHOOTER: Since you want to cruise, get the premium 4L60E from RPM or FLT. Get whatever level has the Sonnax Smart Tech input drum so that it has the most durables 3/4 clutch possible.
I have no experience here, just keeping the tread going until some experts hop in.
02-20-2015, 07:44 AM
#7
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Trans wasn't over $2000 but u need a $600 converter $300 shifter etc to do the swap it all adds up. I priced the swap out at $2700 for everything...RPM level 6 with good output shaft $3000 shipped. Am I really gaining anything going to the 350? Not saving any cash that's for sure plus I have to mess with a shifter install on the 350 and I need pcm flashed to ditch codes
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02-20-2015, 02:40 PM
#8
I am in closer to 3k.After the initial sticker shock I feel that I will be better off if and when something does go. My car is pretty much race only now. When you really look into it there is far more converter choices for a Th 350 and you will end up with a better shifter and sfi flexplate. So some of that $ goes toward upgraded parts plus the $800 for the 8" converter should leave me with a pretty nasty piece. Like said I am looking at it from a race perspective and there is absolutely no sense in having a heavy overdrive trans.If the trans shop would have recommended the Th400 I would go that route but they have not.