PA C4 and Gear Vendors Unit

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Casey72

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Dec 31, 2014
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Location
Western US
My Car
Two '72 coupes.
I finally had some time to address the 23 year old C4 in the '72, replacing it with a PerformanceAutomatic Super Comp C4 and 10" PA converter, adding the Gear Vendors overdrive unit in the process. Bottom line up front: This was a great idea and I'm most pleased with the setup, especially on the interstate, where it shaves off almost 1000 RPM at 65 MPH.

Installing the GV onto the C4 was downright painless, as was the wiring for the unit. Remove tail shaft, bolt it on...with some shims for the shaft end play, so it was essentially a ratchet, wrenches, straight egde and feeler gauge used to get it into place. Once in the car the only tasks were wiring the GV controller and connecting the speedometer pieces. I had the driveshaft shortened to 36.75" to make up for the length added to the transmission with the GV installed.

SCc4GV_zpswukkpwi7.jpg


GVswx_zps5n0zoywa.jpg


I ran into a couple minor snags in the process, one being the virtual interference fit of the PA hardened input shaft with the converter. The tight fit is intentional and requires freezing the shaft overnight and using a mallet and some lube to get the shaft seated in the converter. Bill Schmidt at PA was awesome about replying to lots of (stupid) questions and never kept me waiting for an answer. The other issue I had concerned my attempt to use a single signal generator for both the GV and my electric speedometer by tying both devices into a one signal generator. I tried both signal generators and neither worked in that fashion, so I had to use both.

As for wiring, the GV comes with wiring already terminated for plugging into the control box, as well as the switches for operation. Plug the other end of each cable to ignition power (should be cold while cranking), ground, toggle switch, manual switch, signal generator and solenoid. Super easy.

The PA Super Comp ships with a "cut" shift lever, which has all the stock extensions cut off. This is great if you're using, or plan to use, an aftermarket shifter. Otherwise, you'll have to drop the pan and valve body to swap your original linkage for the cut version. PA has an excellent video of the process on their website, so no drama there.

The improvements are noticeable in operation. The 10" converter flashes at 3200 RPM with the slightly warm 351W and doesn't have the "mush" of the old locally procured 3500 RPM converter. The transmission shifts beautifully and the GV kicks on automatically at ~47 MPH and off again around 30 MPH. In manual mode you toggle the OD on/off as desired with the foot switch, but you have to remember to turn it off well before coming to a stop due to clutch wear issues. Still, it turns the C4 into a 6-speed when you want it.

Anyway, if you're in the market for a contraption like the GV overdrive, it's a pretty cool toy.

 
I really like my GV. I have a lot of fun going into OD in second gear as I am getting on it. It's much less of a drop than going into 3rd. After a bit you will get good at shifting into third while turning the GV off.

If you are in 'manual' mode it will still turn itself off as you come to a stop. Most of the time I turn it off myself but every once in a while I forget. I leave it in manual mode most of the time.

Have you tried lauching it in manual with the red light on? It will shift into OD in first gear as you get close to your max RPM. So FUN!

 
I really like my GV. I have a lot of fun going into OD in second gear as I am getting on it. It's much less of a drop than going into 3rd. After a bit you will get good at shifting into third while turning the GV off.

If you are in 'manual' mode it will still turn itself off as you come to a stop. Most of the time I turn it off myself but every once in a while I forget. I leave it in manual mode most of the time.

Have you tried lauching it in manual with the red light on? It will shift into OD in first gear as you get close to your max RPM. So FUN!
I haven't played with the manual mode much, as I'm still working on my coordination and getting used to the reverse shift pattern. It's still good fun and I'll get the feel for it in short order, I'm sure. At any rate, the instructions mentioned that letting it shift out in manual mode was hard on the clutches, so I do my best to remember when playing around in traffic.

 
I will have to re-read the instructions. I missed that part (or more likely forgot). I remember to take it out about 95% of the time. A panic stop is also an exception. ;)

Without a doubt the GV is one of the top upgrades I have done.

My next move is to get a lower first gear kit for my c6. I want to combine that with a 3.25 rear end (running 3.50 now). I will still get a good hole shot, can go 1/over before maxing out the RPMs and have an awesome cruise in 3rd over.

 
I can't imagine wanting to go higher than 3.50s with the overdrive, but I don't care to drive very fast or travel much with this car. I do want acceleration, though...and some semblance of manners on the freeway.

 
If you don't mind me asking, whats a GV unit for a c4 cost?? I have a pretty well built c4 and have thought of going this route.
$2800ish. They're not cheap, but the C4 doesn't have to be swapped for an AOD or 4L8E. They can do more than just provide a 4th gear, too. For me, being able to run gear ratios beginning with a "4" and still taking the interstate to work was a big selling point.

 
Not sure about the other trannys but the 4r70w I did in conjunction with the baumann controller gives you a lot more than a 4th gear too..multiple modes with the flip of a switch- paddle shifter ready and a lot more. basically your in the same price range as the GV unit maybe a touch more or less depending on how much you source a 4r70w for and how much you spend on the rebuild.

http://www.usshift.com/usq4.shtml

I've been super pleased with my conversion one of the best upgrades I've doon

 
I'd considered such an upgrade/swap, but wanted to stick with the C4 and a completely separate OD unit. If one dies, it dies separately. Paddle shifter stuff really trips my switch, though. I really wasn't up for a swap, in any case.

 
Not sure about the other trannys but the 4r70w I did in conjunction with the baumann controller gives you a lot more than a 4th gear too..multiple modes with the flip of a switch- paddle shifter ready and a lot more. basically your in the same price range as the GV unit maybe a touch more or less depending on how much you source a 4r70w for and how much you spend on the rebuild.

http://www.usshift.com/usq4.shtml

I've been super pleased with my conversion one of the best upgrades I've doon
I have been going back and forth with these two options. I have a good bit of money tied up in my c4 already. With a 3000 stall converter, clutch basket, heavy duty internals, and custom valve body by Broader. I still need to figure out what all it would take to make the 4r70w handle 600 hp.

Q, did you say in another thread that those 4r70w's can be from a 6 banger mustang from 2000's?? Use that as the core for the build? I can get one built pretty much for the cost of parts and a box of beer. My buddy is a certified Ford master tech that has built many of these trannys. I really like the 4r70w as an option. But the simplicity of a GV is nice too!!

Decisions Decisions.....

 
I kicked around both ideas as well. The 4r70w has a nice low first gear (2.84) compared to a C6 (2.46) and more overdrive (.7) compared to a GV (.78). You could go with a lower rear end gear, say a 3.7x with the 4r70w and still end up in the same RPM range as a GV OD with 3.5 gears in the back.

In the end what sold me on the GV is ease of installation and I also already had a built c6. Basically I was able to install the GV myself in the garage without pulling the engine or tranny. I do like some of the options while driving. For example, at 65 mph in OD I can go into passing mode either turning off the OD (1.0) or dropping the transmission into second gear (1.14) depending on how agressive I feel.

 
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