brushwolf
Well Known Member
When reading up on various transmission swaps I encountered the driveshaft angle issue that comes up repeatedly using a longer transmission and X frame with 2 piece driveshafts. Have seen threads where people have gone to a 1 piece driveshaft and even modified the frame center section to tolerate the angle, others where they are just using a shortened front section of driveshaft, etc. But not with a T56, so far anyway..
Have also been scrounging others pics of chassis online to see exactly how the center of the frame is constructed to see how that can be modified, if necessary.
Think the only vehicle I had in recent years with a 2 piece driveshaft is my 88 Suburban and never had issues or vibrations with it and it has probably 180k miles on it, many towing a car trailer with heavy cars on it. Of course, all the stock geometry is undisturbed in that too.
Help me understand this, those of you who have had problems with the driveshaft, or more engineering skills than I do:
The problem with the longer transmission and the original angle/plane of the motor and transmission assembly (assuming we want that to remain very close to stock), is that the longer transmission (say a T56..) puts the output shaft of the transmission lower than a stock setup. That results in an uphill angle from the rear of the transmission to the center driveshaft carrier bearing. Or not? (Assume floor is modified as necessary and transmission mount is modified to keep motor and transmission on the factory plane)
Rough measurement of the T56 including bellhousing to the very end of the output shaft is 32 inches. Measured an old GM 4 speed (think it is an early T10, iron maincase, aluminum tail housing) and a bellhousing and I come up with 22 inches and 6 1/2 inches respectively for a total length of 28 1/2 inches.
So a difference of 3 1/2 inches approximately, but IDT the original 1960 stick transmission was 22 inches from front of main case to end of output shaft, so adjust for that accordingly if there is a difference. My understanding is that there is, and the Show cars or Inland front driveshaft aftermarket piece differs by being shorter roughly the same amount.
Add the 3 1/2 inches of difference between these 2 setups and whatever difference the aftermarket shorter driveshaft front section has to the original front driveshaft section (3-4 inches?) and you now have a total of about 7? inches further back than stock at the end of the T56 output shaft.
So, judging from pics only, that seems like the transmission output shaft would be pointing quite a bit lower in the constricted center of the frame tunnel than the original (or a T10) and that just shortening the front of the driveshaft may not work as the angle of the driveshaft front to the center driveshaft bearing will be quite a bit steeper. Uphill even..
Is it possible to either lower or move the center driveshaft bearing further to the rear (shortening the rear half of the driveshaft instead), or is a one piece driveshaft and attendant frame tunnel mod's in the bottom of the frame center section the only way using the longer T56?
Never ran into this issue on any of my Ford projects.
Thanks, Mike
Have also been scrounging others pics of chassis online to see exactly how the center of the frame is constructed to see how that can be modified, if necessary.
Think the only vehicle I had in recent years with a 2 piece driveshaft is my 88 Suburban and never had issues or vibrations with it and it has probably 180k miles on it, many towing a car trailer with heavy cars on it. Of course, all the stock geometry is undisturbed in that too.
Help me understand this, those of you who have had problems with the driveshaft, or more engineering skills than I do:
The problem with the longer transmission and the original angle/plane of the motor and transmission assembly (assuming we want that to remain very close to stock), is that the longer transmission (say a T56..) puts the output shaft of the transmission lower than a stock setup. That results in an uphill angle from the rear of the transmission to the center driveshaft carrier bearing. Or not? (Assume floor is modified as necessary and transmission mount is modified to keep motor and transmission on the factory plane)
Rough measurement of the T56 including bellhousing to the very end of the output shaft is 32 inches. Measured an old GM 4 speed (think it is an early T10, iron maincase, aluminum tail housing) and a bellhousing and I come up with 22 inches and 6 1/2 inches respectively for a total length of 28 1/2 inches.
So a difference of 3 1/2 inches approximately, but IDT the original 1960 stick transmission was 22 inches from front of main case to end of output shaft, so adjust for that accordingly if there is a difference. My understanding is that there is, and the Show cars or Inland front driveshaft aftermarket piece differs by being shorter roughly the same amount.
Add the 3 1/2 inches of difference between these 2 setups and whatever difference the aftermarket shorter driveshaft front section has to the original front driveshaft section (3-4 inches?) and you now have a total of about 7? inches further back than stock at the end of the T56 output shaft.
So, judging from pics only, that seems like the transmission output shaft would be pointing quite a bit lower in the constricted center of the frame tunnel than the original (or a T10) and that just shortening the front of the driveshaft may not work as the angle of the driveshaft front to the center driveshaft bearing will be quite a bit steeper. Uphill even..
Is it possible to either lower or move the center driveshaft bearing further to the rear (shortening the rear half of the driveshaft instead), or is a one piece driveshaft and attendant frame tunnel mod's in the bottom of the frame center section the only way using the longer T56?
Never ran into this issue on any of my Ford projects.
Thanks, Mike
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