driveshaft help

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dartmathis

mopar or nocar
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Nov 11, 2007
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i have a 67 dart 4 door i'm working on the trans is out it has a 904. all i have is 727 auto trans spares. the question is how much do i have to shorten the driveshaft for the 727 to work in it??
thanks
 
Depends on what you end up using.

You'll need a different slip yoke, and some of them are different styles, and maybe you'll find a used shaft with the "big" joints, so you might want to use a conversion joint at the rear.

BEST advice is to "get dirty," block it up safely and level, and crawl under there with the new slip yoke and MEASURE the thing.
 
I can't vouch for the accuracy of it, but this is a chart that someone posted some time ago that I keep handy http://www.stu-offroad.com/axle/arb/arb-89.jpg. You can try just finding one car/engine/trans/rear combo and then find the same combo with the different trans. I'm sure someone will probably chime in with the right numbers.
 
I've always used 4 1/4-4 1/2" as the difference in length depending on application and where the old seal was riding on the yoke.
 
AFTER you get the trans in measure from seal to center of joint on the end yoke and then from output shaft to center again in the end yoke and bring those measurements with your old shaft to your local driveline shop.
 
i work a a machine shop now...i cut it down myself i was jsut tryin to save a minute all i need to know it the difference in the length of the 727 and 904.....but i got her now guys Thanks
 
Supershafts said:
AFTER you get the trans in measure from seal to center of joint on the end yoke and then from output shaft to center again in the end yoke and bring those measurements with your old shaft to your local driveline shop.
Click to expand...

X2. On the ground, though. Not lifted. Flange of rear diff to end of splined tranny shaft.
 
Balancing is ALWAYS needed, the weld yokes are cast, the slip yokes are cast, even the tubes aren't always perfect... The weld start/finish can make an issue



I can get shafts to .000 if the tubes are the better dom straightened driveline tube and or AL and not the cheaper seemed driveline tube and they still need balancing, very very rarely does a shaft not need weight...

For every 1000 shafts i do i might get 20 that are good if they are street shafts that only see balancing to 3000 rpm, i have yet to do a race shaft that is lightened spinning beyond 3000 rpm that doesn't need weight.

How do you true up each end in a lathe ? you can only hold 1 end at a time ? slip yokes have variances to them, flanges also, some driveline shops without the better balancing machines can't get them perfect or even balanced properly.

How do you hold the shaft at center on both ends at the same time? You use a steady rest and something at one end at a time?
Or are you using machined joints on the head end and in the dead center with a center chuck assembly?
 
You use a steady rest and something at one end at a time?

Yes this is how we've been doing it. Granted we certainly don't do as many as you but the ones we've done have been fine. I know, redneck engineering but it works for us.
 
You Should use them held at both ends and set up rather than the steady rest.

And use a machined joint at each end, take the joint and mill the one side of the cross off..

Slip yokes aren't always perfect, when you true them with a slip yoke they can be off when centered with the joint.

I use a machine that has fixtures for all the different flanges and slips and end yokes we hold them centered exactly how they would be in the car.

They still need balancing, to many differences in weld yoke/slip yoke castings and even tubes.

Use the machined joints in the dead center vs the steady rest
 
OK thanks, next time I need to make a shaft I'll try that. I don't however see much of a need for that right now, but you never know.
 
Wipe one cross off, then you put it in the weld yoke and use the 3rd cross in the head and center, much better that way trust me..
 
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