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Need Info On A Gear Vender's Installation On A 70 RR

soundhd

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Have recently purchased a 70 RR (383 auto). Has a 3:91 gear and would like to keep that but now days we drive longer distances to attend car events and having some sort of an over drive is pretty much the best way to keep the RPM's down while driving on the freeways. Would like to install a Gear Vender's over drive unit. Wondering if anyone else with a 70 RR with a 727 automatic has done it and what issues or problems if any you had while installing it and what was done to resolve those issues/problems. I am sure I am not the only one looking into this. Any info, tips or advice you could post as a reply would be helpful to all thinking about the same thing.

Thanks
 
I have had one installed on my '70RR for the better part of a year now and I would definitely recommend the system. I have a 383/727 combo with the 3.23 gears. I put in the OD unit with the intention of installing some lower gears in the future but after putting on a couple thousand miles I am very happy with the setup and get decent mileage on the highway (13-14mpg).

The install of the new tail shaft was simple. I did it with the tranny out but I don't think it would have been very difficult to do in the car once you drop the mount and tilt the tranny down. The most difficult part was getting the rod that actuates the park pawl back into position.

I did have to make some small tunnel modifications (beat it with a hammer) to clear the adapter for the speedo cable. There is a formed corner in the sheet metal that needs to be hammered out of the way. I think this could be fairly easily undone from the inside of the car if you remove the OD unit later since it is not a cosmetic area and typically has undercoating on it. I also elongated the tranny mount holes a little to tilt the tranny down a degree or so to help resolve this problem.

The only other challenge was the driveshaft. The length change is easily calculated according to the instructions but the combination of u-joints required is odd. I ended up getting the drivetrain shop to order a new yoke for the front of the driveshaft and then a combo u-joint to go between that and the one that comes with the OD unit. There was no combo u-joint available for the small u-joints that came on my factory driveshaft. Any good axle shop should be able to work this out for you. I don't have the paperwork with me so I don't know the exact specs of the parts they used but can look it up for you when I get home if you want, just PM me.

Everything else is pretty straight forward. You will need some kind of bezel to mount the switches and LEDs. I removed my ashtray and fabbed a cover to mount those and a couple of other switches to. Worked out well but does not look original. Again, it is easy to undo if necessary.

Hope this helps and let me know if you have any questions.
 
The shaft will have to be shortened, at which time any driveline shop shouldn't even bother trying to dick around with the 7260 or 90 series joint and just simply install the 1350 weld yoke to match the 1350 slip yoke GV supplies with the GV.

Yes there was a slight issue and use of a hammer for the speedo, i did not change my angle and drop the trans down though, but these were also different year bodies 73 and 78
 
Supershafts, maybe since you've dealt with them you can answer this, but is it just me or does it seem like there's an assload of drivetrain hangin off the back of the transmission mount? Or is there something I'm missing?
 
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Lol i know what you're getting at.... yes it does seem that way, but to calm any fears of something like the issue of it breaking off and getting run over by the back tires or similar it won't happen, now im saying this under my professional driving everything under extreme conditions . . .

I had bought my 1st GV for my truck more than 20 yrs ago to fix a horrible 3/4 split, since the GV is the only actual splitter and OD, i tow and off-road with that truck, that truck has done a good job of shaking me out and pieces out of me, and never loosened a bolt or broke the gv off. That trucks has literally hurt me off-road, a 1 ton power ram crew is not ever ever to be used off-road like a baha truck, it will wreck your body severely
I had loved the gv so much i added it to my then triple duty, street, road race and drag car, made a wonderful difference w/4.88's on the street, had good benefits at the track also being able to split 1st and 2nd at the road course and splitting 2nd at the drags once we found a free 7 hndths.
Then i added one to the RR which was primarily a street/strip use only w/4.30 gear.
All 3 of those cars are driven, and over the years i have never seen nor experienced any issue to ever worry about the weight off the back, the extension/mount housing they make is a very strong durable piece, when it comes to driving i put things thru it's paces, to the extent that im looking for a weak spot.

I became a dealer for GV some time ago since after having multiple units of my own and never a hiccup i decided i could add this to my shop and it wouldn't be a problem, and it hasn't been, i have probably sold more than 35 and installed 30 of them.
They are behind things like large mobile homes (3), tow trucks (4), flat bed (1) pick ups (9, diesel and gas), cars gm muscle cars, ford ranchero and torino gt, a few mopar muscle cars and 3 of them are hemi equipped cars.

I can honestly say that the GV is very good and like my stuff i never ever had a complaint on any of them
 
I have the shorty setup in my car with the GV unit right behind the trans crossmember. I had to lower the trans crossmember about 1-1/2 for it to work. Not ideal, but I didn't want to butcher the car. I'm putting that setup in my superbird clone and I'll cut the tunnel out and make the GV fit right and then put the tunnel back in to clear. I didn't want the super short driveshaft and super long extension in there as it has to hold 1000hp at the flywheel so the shorter the better.

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I have the shorty setup in my car with the GV unit right behind the trans crossmember. I had to lower the trans crossmember about 1-1/2" for it to work. Not ideal, but I didn't want to butcher the car. I'm putting that setup in my superbird clone and I'll cut the tunnel out and make the GV fit right and then put the tunnel back in to clear. I didn't want the super short driveshaft and super long extension in there as it has to hold 1000hp at the flywheel so the shorter the better.
 
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