I think I might be able to use the driveshaft I have out of the Street Duster (904 / 8 3/4) in GodsRods Duster II (904 / Ford 8") by simply swapping out the rear U-Joint.

However, I want to make sure I will have adequate slip yoke engagement in the transmission.

With the overall length of slip yoke being 5", if I have 2 1/2" engaged into the transmission and 2 1/2" sticking out, will that be adequate engagement for a drag car?

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Rob

I’m Mater
The Kentucky Poser

I think That would be fine..


I am sure others will chime in too.

Greg

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http://www.youtube.com/hyperpack

I think more like 1 -1 1/2 is what you are shooting for. 2 1/2" is not much engagement and you may be asking for some vibrations.

Rick

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2 Mopars come with Spark plug tubes. One is a world class, racing machine. The other is a 426 CI. boat anchor!

12.70 @ 104.6

My Personal experience says you should try to get the correct length shaft if you can. The rule I was taught is 1.5" out from the tailshaft to the flat on the yoke Max with a 3/4" minimum.

I had a driveshaft in my GT that was a bit short like yours and it vibrated something fierce, needless to say, I didn't drive it long that way.

.02

~RDE~

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1984 D100 Shorty Custom
Certified Auto Appraiser - RevItUp Classic Appraisals
President - Cherry City Bombers CC
Part of Tyrde-Browne Racing

People that have swapped a Ford 8" into their cars have used the original 7 1/4 driveshaft which would make the 8 3/4 driveshaft quite a bit too short. A driveline shop worksheet I saw had you push the yoke in as far as it would go then pull it back 1" and measure for the correct drive shaft length. The yoke should be most of the way in the trans. I know from experience that if the shaft is 1" too short it will shake like crazy.

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Joshua

Yep, I'd say 2.5" out is a bit much. How long do you need, center-center of the u-joints? I have the OEM 7.25"/904 driveshaft in Project V with the 8" axle.

Lou

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Home of Slant6-powered fun machines since 1988

Driveline shop that has made mine said in all the way, then pull out 3/4" to max of 1"

Richard

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Part of Tyrde-Browne Racing

Fopar's got it. I've run 1.5" out or a bit more and been OK, but not more.

Lou

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Home of Slant6-powered fun machines since 1988

Thanks for all the fedback guys. I had googled it and searched around. Most references are how to measure driveshaft length, not necessarily what is "adequate" for slip yoke engagement.

The driveshaft I have out of the Street Duster is 49" center to center of the U-Joints, 56 5/8" overall length.

The Duster is 53 1/4" from the trans tailshaft to the center of the U-Joint pinion on the diff.

I printed off the sheets from Denny's Driveshaft and will take the measurements and driveshaft down to Republic Diesel in Louisville. The guys at NAPA said that is the "only" place to take it to.

23 days 'til Elk Creek...

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Rob

I’m Mater
The Kentucky Poser