Tranny swap??
March 10th, 2015, 09:57 PM
#1
Registered User
Thread Starter
Join Date: Sep 2013
Location: Florence KY
Posts: 39
Tranny swap??
I currently have a 350th/350 rocket(stock 4bbl) 69 cutlass s. The trans needs rebuild, eventually in the future I may try to find a 455 for my car. My question is how much of a difference would it make if I went ahead and found a 400th and put it in instead of rebuilding the 350th? What's the difference in the two?
March 11th, 2015, 05:47 AM
#2
Connoisseur d'Junque
Join Date: Sep 2010
Location: The Hudson Valley
Posts: 21,183
You do realise that using those two words in the title will inevitably spark a certain amount of merriment and derision, do you not?
As for an answer -
Short answer: TH400 is a heavier-duty transmission, with slightly different 1st and 2nd gear ratios, and a greater parasitic horsepower draw.
Long answer: You can easily find specific differences by searching on line - there is a huge amount of information available about both transmissions, including comparisons, far more than any of us could give you here.
- Eric
As for an answer -
Short answer: TH400 is a heavier-duty transmission, with slightly different 1st and 2nd gear ratios, and a greater parasitic horsepower draw.
Long answer: You can easily find specific differences by searching on line - there is a huge amount of information available about both transmissions, including comparisons, far more than any of us could give you here.
- Eric
March 11th, 2015, 09:00 AM
#3
Old(s) Fart
Join Date: Mar 2007
Location: Northern VA
Posts: 47,366
To the OP's question, the TH400 was factory available in that car. The big changes are the shorter driveshaft, different e-brake cables, addition of the electric kickdown switch, and different shift cable if it's a floor shifter.
March 11th, 2015, 11:22 AM
#5
CH3NO2 LEARN IT BURN IT
Join Date: Jul 2010
Location: Land of Taxes
Posts: 4,861
Just in case you're curious, power losses for TH350 & TH400 auto transmissions:
Please remember these are approximate values, and were provided by Car Craft Magazine but are generally accepted as true amongst trans builders. Values will vary by application, parts installed, fluid viscosity used etc...
Powerglide_____~18-20 hp
TH-350________~32-36 hp
TH-400________~42-44 hp
less for a stick shift
Both 350 & 400 can be beefed up for various high torque applications A 350 will live behind a 455 with a proper HD rebuild. But If it was me Id put a TH400 behind a 455. If you want more gears look into a Gearvendors OD unit behind either. A TH200-4R properly built can do the same but I wouldnt put one behind a high torque sticky tire car or my own car.
Please remember these are approximate values, and were provided by Car Craft Magazine but are generally accepted as true amongst trans builders. Values will vary by application, parts installed, fluid viscosity used etc...
Powerglide_____~18-20 hp
TH-350________~32-36 hp
TH-400________~42-44 hp
less for a stick shift
Both 350 & 400 can be beefed up for various high torque applications A 350 will live behind a 455 with a proper HD rebuild. But If it was me Id put a TH400 behind a 455. If you want more gears look into a Gearvendors OD unit behind either. A TH200-4R properly built can do the same but I wouldnt put one behind a high torque sticky tire car or my own car.
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