1967 Barracuda Driveshaft length a904/8 3/4

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Slantsix64

Slantsix64

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Just dropped in a 8 3/4 into my abody 67 barracuda how much do i have to cut the driveshaft down? its a automatic a904 8 3/4. Thanks in advance!
 
IMHO. the best way would have been to measure how far out of the tail shaft the OE slip yoke measured with the car on the ground and the old rear in. Then with the new rear in put slip yoke in the same distance and with the car flat on the ground measure center of the new rear yoke to the center of the slip yoke.

I saw a post here a few weeks ago that had a links to a drive line company that had a calculator.

As a starting point if you have a OE shop manual it might be listed (my 67 dart has a length listed in the shop manual) BUT don't use it as gospel with out measuring yourself
 
olkingcool said:
i have one i will tell you how long tomorrow
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Cool Thank you! i just measured my current one 51.60 original 7.25/904. i seen that i should be at 49.60 with a 8 3/4 so a 2 inch cut to shorten. ill wait to see what you come up with to be sure
 
These values are for 67 DART based on online info and info in parts book and shop manual.
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What should be consistent is the CL axle and CL u joint difference between 7 1/4 and 8 3/4. Interestingly the driveshaft length is 2.03" shorter for 8 3/4 but the CL to CL is 2.26 longer for 8 3/4. That is a 0.23 difference. go figure!

I'm going to be in the same boat in a few months, so your question is relevant to me too even though the lengths will be different.
 
It should be right at 48.75ish" IIRC.

It's best to slide yoke in trans, car on ground or suspension loaded and measure.
 
olkingcool said:
from center of cap to center of cap 52 1/2
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That sounds like a Dart shaft. Doesn't the Barracuda have a shorter wheel base? like 108" vs Dart at 111"?

Slantsix64 said:
i just measured my current one 51.60 original 7.25/904. i seen that i should be at 49.60 with a 8 3/4 so a 2 inch cut to shorten.
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Dart has a 54.6' shaft (just confirmed on my 67 Dart) with the 7 1/4 and barracuda's 7 1/4 shaft Slantsix64 measured 51.6, that is 3 inches shorter just like the wheelbase.

52 1/2 is longer than Slantsix64's 7 1/4 shaft and the 8 3/4 is longer than the 7 1/4 from axle center-line to U-joint center-line by about 2 1/4 inches so the shaft would need to be shorter by similar amount.

I'm no expert and may be missing something here.

On a side note the Valiant has a 108 wheelbase and in my 67 parts book it calls for a 49.58" shaft with the 8 3/4
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( V1 & L1 are Valiant and Dart \6 ----- V2 & L2 are Valiant & Dart V8)


Oddly in this parts book the Barracuda is not listed.

This is from the 1967 Plymouth Supplement shop manual and is specific to Barracuda:

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You can download a parts book here: MyMopar - Mopar Forums & Information - Parts & Accessories Books

You can download the service manual here (the 67 supplement has the barracuda info): MyMopar - Mopar Forums & Information - Service Manuals
 
If you are doing it yourself, have at it. If you are paying to get it done... MEASURE!

The problem with looking in the "books" is yokes have variations. The shaft should be the same length for ALL 108" wb, 904/8.75 cars. Yet, there are many different lengths.

Here's a list from moparts.
http://board.moparts.org/ubbthreads/upload2/4563759-PartNoDriveshafts.pdf
 
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on my 67 dart with 904 and 7 1/4, the slip yoke is exposed about 1 3/4 to 2 inches (saggy springs, 8" ground clearance)

I don't know how long the slip yoke is or how far it can go in or can come out.



20180309_114126.jpg
 
Dana67Dart said:
on my 67 dart with 904 and 7 1/4, the slip yoke is exposed about 1 3/4 to 2 inches (saggy springs, 8" ground clearance)

I don't know how long the slip yoke is or how far it can go in or can come out.



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I'll just measure it but if the 8 3/4 is 2inchs and 1/4 yoke is longer than the 7 1/4 regardless of wheel base Dodge or Plymouth that should be 2 1/4 minimum cut or exact. But as crackedback suggested I'll just measure it up to be safe.
 
My buddy explained to me with the car jacked up on stands lift up the rear end with a jack to get it leveled stick in the old drive shaft all the way into the end of the trans.

Then measure from the center of the u joint cap until the flange of the rearend which is also the center of the u joint cap.

Get that total measurement and subtract 3/4 of an inch from it and that's how much should be shortened
 
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Measured it up the way the driveshaft shop told me too. Said it would be that 2.5 inches shorter. And also added the shortening would be at the top of the drive shaft before the yoke were the diameter decreases due to the end of the tube having rubber in it.
 
Everything worked out fine. Final length of the drive shaft was 49.25 cut and welded didn't need a balance rides smooth. 3.55 ratio laying rubber! thanks again!
 
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