Share your experience good or bad with gear vendor Overdrive

[chewychevy67]

Anyone have one installed on their rig? Good or bad experience? If you search the net you get a lot of opinions ant different scenarios from RVs to 1000hp cars. Lots of vibration issues on the web. I'm looking to add one to my short box 67 th400 2wd stock height but just want to hear what others have experienced on these before I drop cash on a unit? Pictures always welcome!

[beadblaster]

There is a few used ones for the th400 on ebay right now

[chewychevy67]

Originally Posted by beadblaster

There is a few used ones for the th400 on ebay right now

Nothing on eBay is complete with the harness right now. I'll probably buy a brand new unit if I do. Just wanted to hear how people on the board have done with these units and service?

[GASoline71]

All the drag cars that use them for Hot Rod's Drag Week can't be wrong... those things take a beating and keep going.

Gary

[mike16]

making up a good drive shaft is important.

[chewychevy67]

Yep. Would have that done at a shop but I'm concerned I'd have to lower my transmission mount being its a short Box to make the angles correct so I don't have vibrations. It would be a 1 piece.

[gator2511]

I put a Gear Vendors in my 72 short bed K10, th400 15 years ago. The installation was easy, just measure up the driveshaft length, I had to shorten the rear driveshaft a bit and it worked fine. I left the angles alone, kept it simple and it has worked GREAT for 15 years. I have had no vibrations or any mechanical problems. The brain went dead but they replaced it quickly under warranty. I pulled a 6,000 pound travel trailer to hunt camp for years with no problems. My only complaint is a minor one, it will sometimes give a slightly harder shift from 2nd to first when slowing down to a stop when in auto-shift mode. I love mine and think you just can't go wrong! Oh yeah I have a 1 piece driveshaft I had made at a local shop and it has been flawless!

[mjervis]

Hi I was wondering if you could help me. I am putting a GV in my 72 C-20 and I am not sure where to run the power for the over drive box to on the fuse panel. It needs to go to a fuse that powers an accessory that comes on when key is on but not on crank. I am thinking wipers or radio, but not sure? I can't test it with light by cranking because driveshaft is off getting shortened. Just thought you might remember. Thanks Mike

[HO455]

Originally Posted by mjervis

Hi I was wondering if you could help me. I am putting a GV in my 72 C-20 and I am not sure where to run the power for the over drive box to on the fuse panel. It needs to go to a fuse that powers an accessory that comes on when key is on but not on crank. I am thinking wipers or radio, but not sure? I can't test it with light by cranking because driveshaft is off getting shortened. Just thought you might remember. Thanks Mike

Both the wipers and the radio shut off when the ignition switch goes to the start position. I ran my power from the TH400 kickdown switch power wire.

[Sheepdip]

Originally Posted by mjervis

Hi I was wondering if you could help me. I am putting a GV in my 72 C-20 and I am not sure where to run the power for the over drive box to on the fuse panel. It needs to go to a fuse that powers an accessory that comes on when key is on but not on crank. I am thinking wipers or radio, but not sure? I can't test it with light by cranking because driveshaft is off getting shortened. Just thought you might remember. Thanks Mike

Do what you like or are comfortable with it's your truck....but here's how I ran mine: Pull your 12 volts lead directly from your battery with a 12 or 10 gauge wire to/thru a delay relay that powers up after a few preset seconds, that way you get 12 plus volts all the time anytime . Works flawlessly

G/V brains do not like low voltage period.

The 12 volts powers the brain which coordinates with the signal/speed generator off your speedometer to shoot power to the O/D engagement solenoid. The signal generator power/voltage increases with speed (and just using figures as an example) it stars at zero volts and goes to 16 volts, at or about 40 mph you will have the 16 volts to tell the brain you are going fast enough to generate the oil pressure required to safely engage the O/D.

When you start to slow down the speed generator voltage will decrease when you get to about 20 mph it will be roughly 8 volts, that low voltage signals the brain to cut the power to the solenoid and automatically disengages the O/D.

I run two of these units 1 auto and 1 manual trans with zero issues.

FYI: Delay relay is a... Hella 5 pin 12 volt P/N 5HE996.152-151

[HO455]

Originally Posted by Sheepdip

Do what you like or are comfortable with it's your truck....but here's how I ran mine: Pull your 12 volts lead directly from your battery with a 12 or 10 gauge wire to/thru a delay relay that powers up after a few preset seconds, that way you get 12 plus volts all the time anytime . Works flawlessly

G/V brains do not like low voltage period.

The 12 volts powers the brain which coordinates with the signal/speed generator off your speedometer to shoot power to the O/D engagement solenoid. The signal generator power/voltage increases with speed (and just using figures as an example) it stars at zero volts and goes to 16 volts, at or about 40 mph you will have the 16 volts to tell the brain you are going fast enough to generate the oil pressure required to safely engage the O/D.

When you start to slow down the speed generator voltage will decrease when you get to about 20 mph it will be roughly 8 volts, that low voltage signals the brain to cut the power to the solenoid and automatically disengages the O/D.

I run two of these units 1 auto and 1 manual trans with zero issues.

FYI: Delay relay is a... Hella 5 pin 12 volt P/N 5HE996.152-151

How did you get GV's to share the how they are using the signal generator? They were very closed mouthed about how it works when I talked to them. They wouldn't even confirm if they were using a hall effect sender or a pulse generator.

[chewychevy67]

What gears and tire size do you run?

[gator2511]

I am running 3.73 diff. and a 15" wheel with 32 x 11.5 R15 tires. My suspension is stock 4x4 height. At 70 mph the tach is showing right at 2200 rpm. I can still get low enough for Florida sand and mild swamps but still cruise well!

[72Cheyenne454]

I've got one in my 72 short bed 2wd. Had it for years now with zero issues. Any vibration issues you've read about would be a result of improper install/u-joint angles and have nothing to do the GV unit itself. My truck is currently lowered 2.5/4. I run a one piece shaft that I had made up. No vibration issues with mine and its been trouble free since day one.

This is my second unit, as I installed one in my 86 K30, again with zero issues.

My father currently has one in his 70 K10. His was an older used unit we purchased off Craigslist. Eventually, it gave up and he had to have GV rebuild it several years ago. GV's service was responsive and quick - no complaints.

Here's a few pics of my 72...

[chewychevy67]

What rear gears are you using?

[72Cheyenne454]

Originally Posted by chewychevy67

What rear gears are you using?

3.42 gear
28" tire

[chewychevy67]

Originally Posted by 72Cheyenne454

3.42 gear
28" tire

I've been told 3:54 rear and 29 inch tires (which is what I have) will lug my engine at the 3 to 3 over shift at 47 mph in autodrive. Do you find a loss of power at that shift or Engine lugging at all? What are your rpm aprox at that shift in 3rd over? Sorry for the questions but I am just making sure this will suit my build now rather than 3g later.

[72Cheyenne454]

Originally Posted by chewychevy67

I've been told 3:54 rear and 29 inch tires (which is what I have) will lug my engine at the 3 to 3 over shift at 47 mph in autodrive. Do you find a loss of power at that shift or Engine lugging at all? What are your rpm aprox at that shift in 3rd over? Sorry for the questions but I am just making sure this will suit my build now rather than 3g later.

No problem... I'm happy to answer your questions.

I've never experienced any lugging or loss of power. Maybe with a manual trans it might be an issue at low rpm, but with an automatic the converter provides the cushion/slippage to just pull away with no issues. In fact, I can shift my GV into 3rd over as soon as the trans shifts into 3rd and just pull away. I can do the same in second gear as well. Again, the converter helps to make this possible. Think of it as just running a taller rear gear - 2.73, 2.91.

As for rpm, my factory tach does not read correctly, so I don't have any idea what the rpm's are at a specific speed. However, I did punch the numbers in to an online rpm calculator... 3.42, with 28" tire at 47mph is almost 2,000rpm.

For my truck, in 3rd gear overdrive, with my 3.42 gear is the same as having a 2.67 rear gear with no OD.

My 3.42/28" tire combo is nearly identical in overall gear ratio compared to your 3.54/29" tire set up


I mentioned my dads 70 K10 in a post above. Not ideal, but he's currently running a 3.08 gear with a 30" tire and he uses his GV whenever he's on the freeway. He runs around 1,900 rpm at 70. In OD, his 3.08 is the same as running a 2.40 rear gear with no OD.

[chewychevy67]

Originally Posted by 72Cheyenne454

No problem... I'm happy to answer your questions.

I've never experienced any lugging or loss of power. Maybe with a manual trans it might be an issue at low rpm, but with an automatic the converter provides the cushion/slippage to just pull away with no issues. In fact, I can shift my GV into 3rd over as soon as the trans shifts into 3rd and just pull away. I can do the same in second gear as well. Again, the converter helps to make this possible. Think of it as just running a taller rear gear - 2.73, 2.91.

As for rpm, my factory tach does not read correctly, so I don't have any idea what the rpm's are at a specific speed. However, I did punch the numbers in to an online rpm calculator... 3.42, with 28" tire at 47mph is almost 2,000rpm.

For my truck, in 3rd gear overdrive, with my 3.42 gear is the same as having a 2.67 rear gear with no OD.

My 3.42/28" tire combo is nearly identical in overall gear ratio compared to your 3.54/29" tire set up


I mentioned my dads 70 K10 in a post above. Not ideal, but he's currently running a 3.08 gear with a 30" tire and he uses his GV whenever he's on the freeway. He runs around 1,900 rpm at 70. In OD, his 3.08 is the same as running a 2.40 rear gear with no OD.

That's what I was thinking but it's good to hear from someone who has one with a set up similar to mine. I appreciate the information. Rod.

[davepl]

Can someone explain what it's like to live with one?

Do you have to engage it manually or is there some semblance of automation?

Does it split every gear or just the top gear?

[HO455]

Originally Posted by davepl

Can someone explain what it's like to live with one?

Do you have to engage it manually or is there some semblance of automation?

Does it split every gear or just the top gear?

From their web site.

Performance Electronics
Related to fuel economy, performance, and emissions — GEAR VENDORS overdrive kits include electronics that keep the vehicle in the optimum performing gear. Whether you are driving a older non-computer controlled vehicle or a late model with all the latest emissions computers our electronics provide the interface to ensure maximum performance and correct rpm without lugging or overreving in the wrong gear. The OE factory programming remains intact and our processor just makes it aware of the actual ratio 1,000 of times per second. In older vacuum or throttle linkage transmissions the stock governor on the output shaft instantly slows down the moment the overdrive shifts and so automatically moves the shift point in any overdrive gear up by the correct 28.6%. So both electronic and non-electronic automatic transmissions gain a group of features including a passing gear or climbing gear that is automatically available without driver intervention and is at the split between 2nd and 3rd where you really want it. Electronic options also exist for racing and performance use such a paddle-shifters with our programming already installed by companies like MasterShift, and our AutoShift Sequencer that can work with stock and aftermarket shifters just like many of the race teams use. Our standard AutoDrive electronic however do include several great features for a combination of street/strip use including AutoLaunch for both manuals and automatics.

[fecklessgadfly]

Somebody step in and correct me if I'm wrong, but according to the Encyclopedia Freiburgeria (an episode of Roadkill), The Gear Vendor unit comes on at the flip of a switch, and can split any gear.

From what I understand, you drive the vehicle like normal, then flip the switch when you want the overdrive.

I don't own one, but I plan to after I get the rest of my project done.

[cleszkie]

I installed one in my Blazer over a decade ago. Love it. I have a mild lift, 4.10 gears and 35" tires. Had the rear driveshaft built with a CV joint at the gear vendors end with a Cadillac series 300 slip yoke to conserve length. I tow a 6,000+ lbs boat and loaded car trailer on occasion. No vibration issues.

The Gear Vendor unit allows you to split all forward gears so you get 1st, 1st OD, 2nd, 2nd OD, 3rd, 3rd OD, 4th, and 4th OD. This makes towing up mountain passes easy because you can always find your engine's RPM sweet spot to maximize torque output.

The brain has two settings controlled by a toggle switch, AUTO and MANUAL. In Auto mode, the unit will automatically engage and disengage at preset speeds. This is nice if you have an automatic transmission. In MANUAL mode, you use a floor switch (high beam switch) to turn it on and off at any time. When I first installed my unit I had an auto tranny, and used both the AUTO and MANUAL modes. But mainly the MANUAL mode. I now have a manual transmission so I can only use the MANUAL mode. I also had to move the floor switch to a pull switch mounted on my shift lever since I don't have three feet.

I found my unit used in a junk yard with unknown miles on it. Gear Vendors sent me a users/technical manual for a small fee, which was a great help. I put another 150,000 miles on it with only changing the fluid at regular intervals. When it finally started showing signs of wear (slight vibration, and harder engagements, along with more metal sludge in the bottom of the fluid reservoir), I decided to pull it and send it to Gear Vendors for a rebuild. When I contacted Gear Vendors and told them the serial number of my unit, they told me it was one of their very first versions they sold, and that many upgrades have been made over the years. It was like almost 20 years old. They still offered me the same rebuild service that they offer everyone else that bought one new, which consisted of me getting a fresh, fully upgraded unit off their shelf with a core exchange of my old school unit. They shipped me a new unit the same day, and I shipped them my unit back in their special crate with return shipping pre-paid. At the end of the day it cost me just under $1000 to get a brand new replacement unit. That is pretty darn good considering I paid $100 for the junk yard unit, and was able to get 15 years of reliable service out of it. I suspect my new unit will last longer than 20 years with the design improvements, and me being able to provide proper maintenance from the get go.

[truckster]

Originally Posted by cleszkie

I installed one in my Blazer over a decade ago.

Dumb question time: Does the GV unit go between the trans and transfer case, or is it used only in 2wd? I have a TH350/NP205.

[Greg58]

Originally Posted by truckster

Dumb question time: Does the GV unit go between the trans and transfer case, or is it used only in 2wd? I have a TH350/NP205.

I would assume he can only use it in 2wd, the unit bolts to the back of the transfer case and the driveshaft slides into the OD unit.
I have a US Gear OD unit on an 87 suburban 454 t-400 2wd.
It came on the truck and works well, mine is manual only, takes the 4.11 ratio and converts it to 3.3 or so. You learn how to unload it a little when shifting up and down to avoid harsh shifts.