The converter needs a MINIMUM of .250". I have seen a gap of more than .600". You need this much clearance for expansion of the parts. At .600" there's still PLENTY of engagement with the pump. As far as I'm concerned there's NO problem.
Tom T.
Member
I just finished mating a 66 ST400 to a 1961 364. I have the correct flexplate and crank bushing installed on the nailhead and torqued correctly. After I got the matched set put in the car, I noticed a gap between the flexplate and torque converter. I measured the gap at .260 inches. The converter is fully seated in the transmission and spins freely. I can easily pull the converter up to the flexplate with little effort. My question is this, what is the max distance that allowed between the two prior to bolting them together? I don't want to pull it out too far and disengage or possibly damage the transmission oil pump. I have read through several (GM Generic) forums and am being told that anything more than .25 needs to be shimmed and I should try to achieve a gap between 1/8 and 3/16. Can anyone familiar with the ST400 confirm or deny this?
I also listed this in the transmission forum.
The converter needs a MINIMUM of .250". I have seen a gap of more than .600". You need this much clearance for expansion of the parts. At .600" there's still PLENTY of engagement with the pump. As far as I'm concerned there's NO problem.
Tom T.
Tom Telesco
Classic and Muscle Automotive
12 Cook St.
Norwalk, CT 06853-1601
Day Phone 203-324-6045 ET
NailHead Mini-Starters '53-'66
Adjustable Roller Tip Rocker Arms - All NailHeads
Custom forged pistons
Front & rear neoprene seals
Many other "Nail" parts
"If I can't get it, you don't need it!"
Member
Tom, thank you for the reply. Like I said most of the forums I read were generic to TH350/TH400 and quoted a maximum of 3/16 and minimum of 1/8. We all know that Buick is a breed of its own and that's why I wanted some input from a person that specializes in Nailheads, Dynaflows, and ST400s. Your response raised one of my eyebrows however. The grooves on torque converter arnt even .600 deep. Pulling the converter that far forward would most certainly disengage the pump........no?
Last edited by USMC4LIFE; 02-02-2015 at 12:41 PM.
Member
Tom, I pulled the transmission last night. The notches in the torque converter hub are .500 deep. I also measured the tabs on the oil pump gear. They measure .500 (deep) as well. If I pull my converter forward .260 to make contact with the flex plate, the torque converter will still have .240 contact with the oil pump gear. Does this sound safe, or should I shim the torque converter?
If it makes you fell better use a .125" shim. Can't hurt.
Tom Telesco
Classic and Muscle Automotive
12 Cook St.
Norwalk, CT 06853-1601
Day Phone 203-324-6045 ET
NailHead Mini-Starters '53-'66
Adjustable Roller Tip Rocker Arms - All NailHeads
Custom forged pistons
Front & rear neoprene seals
Many other "Nail" parts
"If I can't get it, you don't need it!"
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