My current driveshaft has about 1" of forward movement available before it comes in contact with the transmission duct cover and then pushing even more will compress the duct cover about another 1". This seems normal to me.
However, I am installing a Gear Vendors under overdrive unit and from the looks of the dimentions in the instructions it looks like they are calling for 7/16" and there is no colapsable duct cover on the overdrive.
Does 7/16" seem like enough play to avoid having the driveshaft hit the trans on a hard lanch? On my current setup the driveshaft would have to move 2" before it would hit something hard.

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67Cuda,FAST EZEFI,340cu,CR=10.25,RollerCam&Rocker (XR268HR,#20-810-9)(#1622-16)(EddyRPM#60779,#7576), (MSD6AL,#6425) A904, GearVendorsOD, 8 1/4,3.55:1, ClassicAir

Bren,

My favorite driveline shop here has been doing driveshafts since 1928. The resident wizard has been working there since 1956. He says push the driveshaft into the tranny all the way, then pull it back out 3/4 inch. Always worked for me. He is the person who solved a rumble for me by showing me the yokes need to be installed 90 degrees to each other....a person who really has seen it all.
rock
'64d100

They designed the unit and built it, Why not do as they say? If you have a question with their instructions, why not ask them. Get it from the Horses mouth.

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Charrlie_S
65 Valiant 100 2dr post 170 turbo
66 Valiant Signet 170 nitrous
64 Valiant Signet
64 Valiant 4dr 170
64 Valiant 4dr 225

The thing you have to remember is that the driveshaft has to move back and forth as the rear axle moves. The overdrive unit would presumably be mounted in a fixed location; there will be considerably less fore and aft movement in that case.

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David Kight
'62 Valiant Signet, White
'98 Dodge Dakota
'06 Jeep Liberty

Growing older is unavoidable but growing up is strictly optional.

There closed right now.

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67Cuda,FAST EZEFI,340cu,CR=10.25,RollerCam&Rocker (XR268HR,#20-810-9)(#1622-16)(EddyRPM#60779,#7576), (MSD6AL,#6425) A904, GearVendorsOD, 8 1/4,3.55:1, ClassicAir

2" is right on the edge of being too much. General rule of thumb is 3/4-1". 7/16" does sound a little snug.

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Official Cookie and Mater Tormentor.

Bren, is this the GV unit that bolts right on the back of the trans, in place of the tail housing, or the one that uses a short drive shaft between the trans and the GV unit?
Is this in your Cuda or another vehicle?

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Charrlie_S
65 Valiant 100 2dr post 170 turbo
66 Valiant Signet 170 nitrous
64 Valiant Signet
64 Valiant 4dr 170
64 Valiant 4dr 225

Yes it replaces the 904 tailshaft.
http://tinyurl.com/24tcnt
It adds 13 3/4" to the driveline.
It is for the Barracuda. Bought it for a number of reasons. Wanted overdrive so I can put back in the 3.55 gears and willmimic a 2.77 rear gear. With the 3.07 gear I have now the overdrive will mimic a 2.40 rear gear. Another reason is I'll beable to split shift 2-3rd gear at the track. As you may remember, I have the low gear set in my 904 and 2-3 shift is pretty dramatic. I hoping to run through the traps in 2nd over whick should help me keep what was gained by using the low gear set.
Someday when the Hemi goes in I plan to use a 904, so I beable to still use the setup, however it will be quite some time before that happens. It will be a year or two and hopfully some of the electronic costs come down by then or a nice kit is available.

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67Cuda,FAST EZEFI,340cu,CR=10.25,RollerCam&Rocker (XR268HR,#20-810-9)(#1622-16)(EddyRPM#60779,#7576), (MSD6AL,#6425) A904, GearVendorsOD, 8 1/4,3.55:1, ClassicAir

I think I am with Zilla on this. 7/16 being a little too tight. I would lean more toward the 3/4 to 1 inch figure, but I didn't design or build the piece, much less ever install one.

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Charrlie_S
65 Valiant 100 2dr post 170 turbo
66 Valiant Signet 170 nitrous
64 Valiant Signet
64 Valiant 4dr 170
64 Valiant 4dr 225

I am going with 15/16" play based on my calcs (shown below). Ofcourse I will be calling GV monday to confirm.
http://tinyurl.com/2yd298

I didn't draw everylittle detail, like the new yoke supplied, but the accuracy is to the nearest 1/16" at key points.
According to the installation book, the overall lenght of the unit installed with a slip yoke setup is 31 1/16" So I am real close, but I don't get how their coming up with 7/16"

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67Cuda,FAST EZEFI,340cu,CR=10.25,RollerCam&Rocker (XR268HR,#20-810-9)(#1622-16)(EddyRPM#60779,#7576), (MSD6AL,#6425) A904, GearVendorsOD, 8 1/4,3.55:1, ClassicAir

I find that I need at least 1/2" or else it is a real hassle getting the U-joint into the rear end yoke "cups".

I always install all the parts into the car and then measure before having a driveshaft made.
DD

Started installing the GV and it sure is a pain on jack stands. The painfull part is clearancing the floor pan tunnel with no room to swing a hammer. The air hammer has helped alot but theres nothing that works better than a good wack with a 2lb hammer. One thing that should be noted is that a "good" sales person will lie to you about the installation clearancing requirements. I was told that two "dimpals" about the size of a quarter would need to be hammered in at 10 and 2 oclock. More like move the whole 9 to 3 oclock area up and out a 1/2" and do this over a 8" area. I called them and after I have the unit bought and paid for they say thats pretty normal. If I had known that I would have still bought it, but I would have been prepared for it.
Its almost in. I am letting the air compressor cool down and giving the neighbors a break from the air hammer.
Driveshaft yoke play according to GV is 5/8". I went with 3/4"

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67Cuda,FAST EZEFI,340cu,CR=10.25,RollerCam&Rocker (XR268HR,#20-810-9)(#1622-16)(EddyRPM#60779,#7576), (MSD6AL,#6425) A904, GearVendorsOD, 8 1/4,3.55:1, ClassicAir