Gear Vendors Overdrive

[Richard Cranium]

There must be some here who have installed it. Real world opinions appreciated.

Also, thoughts on this alternative "shortie" system....

727 "Shortie" OVERDRIVE KIT

Chrysler Overdrive transmissions, 727 Overdrive Kit, Shortie Overdrive Kit for Torqueflite 727 transmission, Fuel economy for Dodge, Plymouth, Chrysler cars and trucks, better mileage for Mopars

smrtrans.tripod.com

 

[furyus]

I have thought about the shortie setup for years. And I thought about GV in general. I have no desire to put anything chevy in my car. The biggest detractor for me was the driveline angles, and the associated vibration. This seem to cure that.

 

[diesel_lv]

I've got a GV in my '67 Coronet. It's nice, but not as much o/d as I would like. I put mine in on my garage floor on jack stands on my back. P.I.T.A. They are extremely durable though. I use it as a plain o/d, not gear splitter. If you have an air hammer, get a round head attachment for it and use that to massage the floor pan where it needs it. It doesn't take too much. 3.73 gears, 26.5" tires, 3,200 rpm at 80.

 

[493 Mike]

I have 2 of them. The one in my 66 wagon has been used for 10 years or so by me. I also use it for the OD and it makes quite a difference with my 4.30:1 gear. I can cruise comfortably and it certainly helps fuel milage. I haven't tried gear splitting yet but, I intend to in my 65.
Mike
I am editing this post to add: I did extensive work to the tunnel to get the GV unit to fit (to my standards) and service. The tunnels in 65 and 66 were quite small in comparison to later year "B"s. I am very pleased with the outcome in the 65. The 66 job-not so much. That's on me though.

 

[HawkRod]

I put a GV OD in my 73 Road Runner that I drove across country. I put 11,097 miles on it for that trip alone and it has worked flawlessly.
Like others have said, I do not use it for gear splitting - I simply use it for the OD (.78). I do wish it had a more aggressive OD ratio, but then it wouldn't be very good at splitting gears (according to GV).

Overall I am happy with it. I did, however, find that I needed to massage my transmission tunnel more than I was led to believe. It wasn't just a small tap or two with a hammer...

 

[Kern Dog]

I've got a GV in my '67 Coronet. It's nice, but not as much o/d as I would like. I put mine in on my garage floor on jack stands on my back. P.I.T.A. They are extremely durable though. I use it as a plain o/d, not gear splitter. If you have an air hammer, get a round head attachment for it and use that to massage the floor pan where it needs it. It doesn't take too much. 3.73 gears, 26.5" tires, 3,200 rpm at 80.

I had one for a few years. It did work but as stated, the overdrive ratio of .78 wasn't that great compared to the .64 I have with the 5 speed manual.
There are several advantages to this though. If you decide to remove it for any reason, It is reversible with almost no evidence that it was in the car. In a long wheelbase car like a Charger, the drive line angles are not too bad. It is durable. The electronics have improved greatly. The one I had was a rebuilt first gen model. The dang thing would go into OD but then fail to disengage as I slowed to a stop. The goal is to have it work as just a 4th gear.

 

[diesel_lv]

I had one for a few years. It did work but as stated, the overdrive ratio of .78 wasn't that great compared to the .64 I have with the 5 speed manual.
There are several advantages to this though. If you decide to remove it for any reason, It is reversible with almost no evidence that it was in the car. In a long wheelbase car like a Charger, the drive line angles are not too bad. It is durable. The electronics have improved greatly. The one I had was a rebuilt first gen model. The dang thing would go into OD but then fail to disengage as I slowed to a stop. The goal is to have it work as just a 4th gear.

Mine is 3 yrs old. So I'm pretty sure all new electronics. It engages at 40mph and disengages at 25mph like clockwork.

 

[furious70]

Had one in a crew duallie. With a nice 440 and 4.10's we never needed to shift out of od up hills. Which means a 3.54 or 3.73 gear would have really made the truck work well.

 

[Richard Cranium]

Thanks for the replies everyone. Any thoughts on the shorty version?

 

[493 Mike]

Thanks for the replies everyone. Any thoughts on the shorty version?

Do you need the shorter length? Will it fit better in your tunnel? It does make a longer driveshaft but, still shorter than stock. The long adapter version requires a cute little driveshaft!
Mike

 

[Richard Cranium]

Do you need the shorter length? Will it fit better in your tunnel? It does make a longer driveshaft but, still shorter than stock. The long adapter version requires a cute little driveshaft!
Mike

I brought up the shorty version only because it wasn't so damn long and out of balance when installing the transmission. Im thinking about this in a 1964 wagon. From what you have experienced, I understand the tunnel is smaller than on later cars.

 

[Greg Ducato]

You will need the short 727 output shaft as used in mid 70's trucks to use the shorty GV kit. That means your trans will require total disassembly and shaft replacement. One other thing to consider is stall speed on your torque converter. If your cruise rpm is close to your stall speed the converter will generate an excessive amount of heat. Plan on using a big cooler regardless.

 

[furious70]

No experience with the shorty but on the surface it seems stronger to have that 50lbs hanging a foot closer

 

[Kern Dog]

One other thing to consider is stall speed on your torque converter. If your cruise rpm is close to your stall speed the converter will generate an excessive amount of heat. Plan on using a big cooler regardless.

Oh crap, I forgot about stall speed.
Yes, that definitely matters. I had a 3000 stall converter and when I was in overdrive, the car felt lazy until I floored it.

 

[493 Mike]

No experience with the shorty but on the surface it seems stronger to have that 50lbs hanging a foot closer

The furnished extension housing is beefy enough to support the rock of Gibraltar.
Mike

 

[493 Mike]

I brought up the shorty version only because it wasn't so damn long and out of balance when installing the transmission. Im thinking about this in a 1964 wagon. From what you have experienced, I understand the tunnel is smaller than on later cars.

My tunnel replacement. You would not need the transmission (front) portion. I did, as I elected for maximum engine set back. I had a S/M shop roll a U shaped piece 9 1/4" diameter with "legs" long enough to extend past the lowest floor pan area and stitch welded the inside first followed by seal welding the bottom. 18 gauge metal.
Finished floor turned out nice.
Mike

 

[hunt2elk]

My tunnel replacement. You would not need the transmission (front) portion. I did as I elected for maximum engine set back. I had a S/M shop roll a U shaped piece 9 1/4" diameter with "legs" long enough to extend past the lowest floor pan area and stitch welded the inside first followed by seal welding the bottom. 18 gauge metal.
Finished floor turned out nice.View attachment 1326729
Mike
View attachment 1326727

Looks nice. Wondering why you didn't install rear torque boxes since you did the fronts?

 

[493 Mike]

Looks nice. Wondering why you didn't install rear torque boxes since you did the fronts?

With the inboard spring mounts I deemed it solid enough. Has a 4 point roll bar also.
Mike

 

[diesel_lv]

@493 Mike that tunnel looks big enough to put a modern 8sp from a Hellcat in it.

 

[Dan64]

I installed one in my 64' Polara (standard lenght) I had to add some clearance to the floor but not that big of a deal. In talking to the guys at G.V. they mentioned that it helped to also slightly slot the trans cross member bolt holes. With 4.10's it helps, it makes it about the same as a 3.21 ratio. I only use it as a overdrive and don't split gears.