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Help 8 1/4 vs 8 3/4 Driveshaft length??? #294232 04/20/09 07:50 PM 04/20/09 07:50 PM
Joined: Oct 2007 Posts: 1,951 Toronto Ontario Butt Ugly OP top fuel
Butt Ugly OP top fuel Joined: Oct 2007 Posts: 1,951 Toronto Ontario	Swapping out to an 8 3/4, if I did the math right I have added .66" to the "center line of chuck to the yoke center". Please tell me I don't have to shorten the drive shaft. Is ther enough play in the front yoke??? Faster Horses, Younger Women, Older Wiskey, More Money --- Tom T

Re: Help 8 1/4 vs 8 3/4 Driveshaft length??? [Re: Butt Ugly] #294233 04/20/09 10:20 PM 04/20/09 10:20 PM
Joined: Oct 2005 Posts: 9,065 Milwaukee, WI In_The_Pink master
In_The_Pink master Joined: Oct 2005 Posts: 9,065 Milwaukee, WI	I'm confused. Did you insert the driveshaft yoke into the transmission's tailhousing (in the normal position, based on visible wear) and measure trans yoke center to rear differential yoke center? That measuring method will allow for driveshaft movement upon suspension compression and elongation.

Re: Help 8 1/4 vs 8 3/4 Driveshaft length??? [Re: In_The_Pink] #294234 04/20/09 11:13 PM 04/20/09 11:13 PM
Joined: Jul 2008 Posts: 403 NE Ohio 7 71 FJ6 Charger mopar
71 FJ6 Charger mopar 7 Joined: Jul 2008 Posts: 403 NE Ohio	I have seen it and done it myself. Never had problems or heard of any. I went by the wear pattern on the slip yoke.Just a driver though,no racing. What kind of car? '71 383HP FJ6 Charger SE

Re: Help 8 1/4 vs 8 3/4 Driveshaft length??? [Re: Butt Ugly] #294235 04/21/09 01:03 AM 04/21/09 01:03 AM
Joined: Jan 2003 Posts: 3,078 Edmonton, Alberta, Canada Dartman75 master
Dartman75 master Joined: Jan 2003 Posts: 3,078 Edmonton, Alberta, Canada	I made the 8.25 to 8.75 swap last year and if I recall I had to take 3/4" out of it. Might depend if you're swapping yokes though as I went to the 1350 at the same time. I'd alwasy suggest measuring rather than guessing. For mine I put the shaft all the way into the tail houseing, pull it out 3/4" and measure that.

Re: Help 8 1/4 vs 8 3/4 Driveshaft length??? [Re: Butt Ugly] #294236 04/21/09 02:15 AM 04/21/09 02:15 AM
Joined: Jan 2003 Posts: 2,001 s. e. pa. C calrobb2000 top fuel
calrobb2000 top fuel C Joined: Jan 2003 Posts: 2,001 s. e. pa.	hi my son did his duster 2 weeks ago , had to use a 3/4 in shorter shaft !

Re: Help 8 1/4 vs 8 3/4 Driveshaft length??? [Re: calrobb2000] #294237 04/21/09 03:13 AM 04/21/09 03:13 AM
Joined: Jan 2003 Posts: 9,826 las vegas 70AARcuda master
70AARcuda master Joined: Jan 2003 Posts: 9,826 las vegas	did the swap 4 yrs ago... never shorten the driveshaft... Tony 70 AARCuda Vitamin C 71 Dart Swinger 360 10.318 @ 128.22(10-04-14 Bakersfield) 71 Demon 360 10.666 @122.41 (01-29-17 @ Las Vegas) 71 Duster 408 (10.29 @ 127.86 3/16/19 Las Vegas)

Re: Help 8 1/4 vs 8 3/4 Driveshaft length??? [Re: 70AARcuda] #294238 04/21/09 09:13 AM 04/21/09 09:13 AM
Joined: Jan 2003 Posts: 16,123 Grand Haven, MI patrick I Live Here
patrick I Live Here Joined: Jan 2003 Posts: 16,123 Grand Haven, MI	did the swap in my M body 4 door (112.7" wheelbase), I went from a 7.25" rear to an 8.75". I grabbed the drive shaft out of a mirada (112.7" WB) with an 8.25" and ran it as is, didn't need to shorten it at all, never had a problem, ran it for 2-3 years until I swapped the 904 out for a 42RH OD. 1976 Spinnaker White Plymouth Duster, /6 A833OD 1986 Silver/Twilight Blue Chrysler 5th Ave HotRod SOLD!* 2011 Toxic Orange Dodge Charger R/T 2017 Grand Cherokee Overland 2014 Jeep Cherokee Latitude (holy crap, my daughter is driving)

Re: Help 8 1/4 vs 8 3/4 Driveshaft length??? [Re: patrick] #294239 04/21/09 02:05 PM 04/21/09 02:05 PM
Joined: Oct 2007 Posts: 1,951 Toronto Ontario Butt Ugly OP top fuel
Butt Ugly OP top fuel Joined: Oct 2007 Posts: 1,951 Toronto Ontario	Thanks for all the info, looks like I'll try the existing drive shaft and if it don't work I'll have to shorten it. Hope to have it swapped out later this, I'll let you know. Doing the swap in a 79 Volare wagon. Faster Horses, Younger Women, Older Wiskey, More Money --- Tom T

Re: Help 8 1/4 vs 8 3/4 Driveshaft length??? [Re: Butt Ugly] #294240 04/21/09 09:18 PM 04/21/09 09:18 PM
Joined: Nov 2006 Posts: 1,459 oklahoma F forphorty pro stock
forphorty pro stock F Joined: Nov 2006 Posts: 1,459 oklahoma	you can put a shim between the front spring hangar and the body to move the rear end farther back . done pretty often on A bodies to help center the wheel in the wheel opening and gain tire clearance at the leading edge. Im not real familiar with F bodies. Around here it doesnt cost too much to have a driveshaft cut. I just paid 67$ with balancing.

Re: Help 8 1/4 vs 8 3/4 Driveshaft length??? [Re: forphorty] #294241 04/22/09 01:24 AM 04/22/09 01:24 AM
Joined: Jan 2003 Posts: 27,471 So Cal autoxcuda Too Many Posts
autoxcuda Too Many Posts Joined: Jan 2003 Posts: 27,471 So Cal	Does anyone know the difference (if any) in U-joint placement between the 8 3/4 and the 8 1/4 rear ends.

Re: Help 8 1/4 vs 8 3/4 Driveshaft length??? [Re: autoxcuda] #294242 04/22/09 09:02 PM 04/22/09 09:02 PM
Joined: Oct 2007 Posts: 1,951 Toronto Ontario Butt Ugly OP top fuel
Butt Ugly OP top fuel Joined: Oct 2007 Posts: 1,951 Toronto Ontario	Quote: Does anyone know the difference (if any) in U-joint placement between the 8 3/4 and the 8 1/4 rear ends. Placement?? or Size?? Mine are the same size for the swap. 8 2/3 is .66" longer. Faster Horses, Younger Women, Older Wiskey, More Money --- Tom T

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