Driveshaft help

[DragginMAster]

I am planning on swapping the SB 904 tranny out of my dart and replace it with a SB 727.

The question I have is, How long does the drive shaft need to be?

I have a couple laying around that I can take to the shop to have modified if necessary but I want to have the least amount of down time as possible, and since I need to take the 727 to the shop to be rebuilt for old times sake, I figgered if I could get the drive shaft done around the same time I would not have to let the car sit or do lots of extra work, but I do not know exactly how long I need the shaft to be.

Can anyone with a similar set up let me know how long their drive shaft is?

68 dart, SB 727, 8.25 rear end.

thanks

 

[ramhemi]

A 340;727 and a 8 3/4" rea end has a 43.1 inch shaft.

 

[DragginMAster]

is the third member of a 8.75 longer than an 8.25?

thanks for the info.

 

[mikedevore]

is the third member of a 8.75 longer than an 8.25?

thanks for the info.

yes

 

[DragginMAster]

*bump*

anyone at all with the same set up that I am looking to recreate?

360, SB 727, 8.25 rearend

 

[ramhemi]

I got my 70-71 parts book out,the best I can tell is the shaft should be 49.2".

 

[340mopar]

A 340;727 and a 8 3/4" rea end has a 43.1 inch shaft.

Would this be in a Dodge or in a Plymouth? Because a '68 Dart(111") has a different wheel base than a '68 Valiant/Barracuda(108").


An 8 1/4" pinion length(11.69") is .66 shorter than an 8 3/4"(12.35") so If you used a 340/727/8-3/4 driveline it would be .66 to short.



Chuck

 

[Ace]

Just put a yoke in it and measure the distance from the U-joint centerline to the bellhousing face on the two transmissions. The difference will give you a pretty good idea how much longer the new shaft needs to be. Best way to do it would be to measure it with everything installed, U-joint centerline to U-joint centerline, with the weight both on and off the suspension in case there is any unused fudge factor in the existing setup. Want to get all the yoke spline used you can without bottoming the yoke when the suspension unloads.

 

['64 Cuda]

I read somewhere that you should put the yoke in all the way & then pull it back out about 3/4" before you make your measurement. Don't remember where I read it though.

 

[redfastback]

you put the yoke all the way in the tranny. measure centerline of front u-joint cap to centerline of rear u-joint cap and then subtract 1". car needs to be on the suspension.

 

[66dartgt]

First verify if the 727 trans is the same length as the 904. If it isnt then you would be best off waiting until the trans and axle you intend to use are in the car and the car is on the ground. The measurement according to the mopar chassis book is the distance from the outputshaft of the trans to the Center line of the differential u joint car on the ground, then subtract 3.5 inches, for the u joint center to u joint center dimension. You will need a different trans yoke as well - hopefully this is useful.