Posted By: B3422W5
Race driveshaft measurement questions - 03/20/18 11:39 PM
Hey guys need some help.
I am swapping my 727 out for a 904 here shortly. Have a 69 Dart. Has ladder bar suspension, so not sure the rearend( 8:75/ 489 case) sits exactly where it would have from the factory.
Anyhow, i am hoping to do the swap all in one day for several reasons.
So my thought is to find out if i can what the measurements are supposed to be were one to order a driveshaft for my car the way it came from the factory(340/727) if somebody hopefully has them, then measure what i actually have. If they agree, the rearend is where its supposed to be.
Then knowing that, i can hopefully find measurements for a 904, and order up a driveshaft and have it on hand the day i do the swap
Make sense? If the factory 727 measurements are correct, should be fairly easy to determine what i need measurements wise for the 904. Somebody has probably already done this on here...... i hope
TIA
Posted By: Dave Hall
Re: Race driveshaft measurement questions - 03/21/18 01:10 AM
Mark Williams and others have charts on their websites for ordering purposes. I wouldn't worry about the wheelbase if it's within a couple inches. I shortened my Challenger because the tire is centered better in the wheelhouse. Moving the ladder bar at this point would be a pretty major undertaking. Just get everything in where you want it/ where it goes then take the required measurements and order your driveshaft. I highly recommend the MW yoke for both ends with 1350 joints.
Posted By: AndyF
Re: Race driveshaft measurement questions - 03/21/18 01:15 AM
Cass at Doctor Diff can help you out. He has a form on his website for the Strange driveshafts.
Posted By: fourgearsavoy
Re: Race driveshaft measurement questions - 03/21/18 03:10 AM
Cass at Doctor Diff can help you out. He has a form on his website for the Strange driveshafts.
I used the Strange order form and it came out perfect with nice solid 1350 joints and a new slip yoke.
Gus
Posted By: B3422W5
Re: Race driveshaft measurement questions - 03/21/18 04:20 PM
Think people missunderstood what i need.
I know the different driveshaft makers have measurement charts.
What i need are those measurements someone has taken for a car with 727 and 8.75 using a 69 Dart or equalivent.
I can then compare that to my actual measurements, to make sure my rear is in stock location.
Knowing that, i can then hopefully get 904 measurements as well, without having to actually put the 904 in the car and have it sit while i order a driveshaft.
I want to order my 904 shaft ahead of time for the swap in other words, and if everything is in stock locations, others must have taken these measurements already that i can use to order from
Posted By: B3422W5
Re: Race driveshaft measurement questions - 03/21/18 07:24 PM
Got what i was looking for from posting same thing on another site
69 Dart with v8 and 727........ 47.81 inches center of yoke to center of yoke
69 Dart with v8 and 904.........52.27 inches center of yoke to center of yoke
So now if the 727 in my car is the same 47.81 inch measurement, i can add the extra length of the 904 measurement on an order a 904 driveshaft with very good chance it will fit as it should. That way i can have everything on hand to do the swap without waiting to order stuff.
Posted By: HardcoreB
Re: Race driveshaft measurement questions - 03/21/18 09:11 PM
Hello Don! I guess my only advice here would be put the rear where you want it and then get your own measurement. Because even ride height has an effect on length. I say this because when you move the axle back an inch or so on that body it allows for a nice TALL tire if that's a consideration. IMO It also centers the wheel in its opening better.
Posted By: Racer33
Re: Race driveshaft measurement questions - 03/21/18 09:23 PM
If you chart is correct assuming the same rear end in both the 904 and 727 cars you should be able to just order a driveshaft that is 4.46" longer then your existing driveshaft even if your axle is not in the stock location
Posted By: justinp61
Re: Race driveshaft measurement questions - 03/21/18 09:38 PM
Don who are you going to have do your new shaft? When I mini tubbed my dart I had Dynotech build me a nice shaft with 1350 u joints. The car has always had a vibration since. I thought maybe my pinion angle or drive line angles were off and over the course of several years tried different angles but nothing helped.
I've been working on the car for a couple months changing a few things and had the transmission out, while it was out I decided to have my local drive shaft builder check my Dynotech shaft for balance. It was way out, he said he thought it was going to jump out of the machine. He added a big weight on each end to balance it, when I went to pick up he ran it in his balancer and showed me the indicators and there was very little movement on either end.
It may just be a fluke but IIRC that shaft was well over $400 and has caused me much grief and wasted time chasing my tail.
BTW, I haven't ran it yet and and will not until I get this brake pressure figured out.
Posted By: B3422W5
Re: Race driveshaft measurement questions - 03/22/18 12:03 AM
If you chart is correct assuming the same rear end in both the 904 and 727 cars you should be able to just order a driveshaft that is 4.46" longer then your existing driveshaft even if your axle is not in the stock location
Yep. Exactly my plan..... just do a couple of measurements to verify
Posted By: fourgearsavoy
Re: Race driveshaft measurement questions - 03/22/18 01:21 AM
The 2 words "should" and "assume" shouldn't be used when ordering a driveshaft because all cars are differn't
