Technical Gear Vendors Overdrive from Motorhome

I have a chance to get a TH400 with a Gear Vendors unit behind it from a 1978 GM RV—don’t know the gear ratio it was in front of, but I’m guessing somewheere around 4.**. Anybody know if these gear vendor units are any different, than say for a regular car or truck? How feasible would it be to make it useful for a car or truck? I was planning on putting it behind a 350 SBC with 3.42 gears.

These are the pics of the ****** and the GV unit. Not sure about the brake booster looking thing on it, if anybody could shed some light on that, that would be great.

Thanks fellas!

Frank

 

Don't know anything about the box, but that ''brake booster looking thing'' looks like a park brake / hand brake, to me..

 

Call Gear Vendors to get the details but it would be best just to use a Turbo 400 so you don't have to buy the adapter for the Turbo 350, The big drum on the tail shaft is the emergency brake and that will need to come off, otherwise it should work. Check them out here: http://www.gearvendors.com/index.html

 

Sorry it wasn’t clear. I was planning on buying both the TH400 with the GV unit to put behind the 350 SBC. I was going to take out the TH350.

 

Oops, my mistake! They are all the same (truck or car) and are bulletproof. I have one I bought for $400 out of a 3/4 ton Chevy van.

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Part# 3D0475 is for a Motorhome, 3-Spd Auto with parking brake

 

Talked with GV at their booth at the LARS. Very informative and will help you with questions. Give 'em a buzz.
I'd buy one. Looking for one to go behind my C4....just sayin'

 

I run a GV overdrive and I love it... very bullet proof. As far as the e-brake mechanism you have there... I believe that trans is actually a TH475 used on motorhomes and other large vehicles. They use straight cut gears...more heavy duty. And an e-brake hooked directly to the shaft. Seems pretty useful for a hot rod application to me....

 

Did you get the control box with it? I have the GV unit in my 39 ford coupe behind a 302/c4 and it works great, you can use it in the manual mode and shift it in anytime you want above about 30 mph it will shift out when you slow to 25 mph, with it in automatic it will shift in overdrive at about 47 mph and shift out at 25 mph. I use a pulse generator for my electronic speedometer but it can work with a manual speedometer also. Contact GV for information on adapters and parts and the instructions how to set it up. Great way to put overdrive behind any motor trans. combo.

 

the parking brake might be something you don't need...and yeah, the 475 is a neat transmission.

Kind of heavy, but overdrive is nice. I have a GV in my little race car, behind a blown 427. Which is not as hard on a transmission as hauling around a motorhome is.

 

I was a dealer for GEAR VENDER for years. Yes this is a great find for your hot rod. The brake is not necessary for your car. These are great for highway speeds. You can use low gear like 4.56 to 4.11 in rear end and still use GV to get super high ratio, Now do some homework and check your tire size and do the math. This gear splitter can give you extra power and fuel economy. Squirrel said that it works on his car. They are bullet proof. Motor homes are a lot heavier than your car. you will like this and wish you hade it before.

 

I had a Gear Vendor in an 85 GMC dually with a 489 BBC and 4.56 gears. Full throttle shifts into OD were nothing for it. Splitting 2nd and 3rd is great also.

 

Do I see the start of a new "Hot Rod Trend" (kinda like the "T5 Fever" that swept through a few years back?).

 

I run a GV OD on my 49 Chevy PU behind a TH350 and could not be happier. You can split all the gears to actually give you 6 forward speeds. My rear is a 3.80 ratio and with the OD engaged in final drive its around 2.90.

 

Funny thing about the GV overdrive...it was around 50 years ago, as an OEM overdrive on foreign cars. So it's almost sort of traditional. But not.

 

Gearvendors overdrive started out as Lay**** - De Normanville in England. The were used in Jags,Aston Martins, Volvos, Austin Healys, and even AMC Pacer,Gremlin, and Hornets in the mod '70's. Gearvendors was a dealer and bought out Lay**** when they went belly up. Gearvendors did some minor internal changes including increasing hydraulic pressure to te o/d ring from 500 psi to 900psi. They are generally a . 68 to .70 reduction overdrive. They work best with rear ratio in the high 3s to mid 4s. I am running an original Lay**** unit from a '76 Pacer in my roadster with 3.70 gears and love it. A simple toggle switch to control the solenoid is all that is necessary for operation. However, using such a switch requires you to manually turn the unit off at low speed and NEVER backup with it engaged (instant disaster).
Control units can be purchased from Gearvendors or found on Ebay. I'm using a Skydrive to power my speedometer and it has an accessory feature to turn an item on and off at a set speed. Couple that with a toggle switch in line and a control unit isn't necessary. Whatever way you go, you will find the Gearvendors unit a great addition to your ride. I've been running mine 10 years with ZERO problems .

 

Seems like they came on a Swedish car originally, I remember reading about them a few years back. I think that you could break one but you would have to work at it. I would run one and never give it a second thought.

 

I set up my own design control system. Micro switch on the shifter lets a relay energize only when the lever is in 3rd gear (manual valve body transmission). A push ****on turns on the relay. Bumping the shift lever pops it out of OD. Pretty simple system, that took a long time to invent. I can't split gears, though.

 

P'nB- the Lay**** OD came on Volvos- pretty much the same thing, tho

 

I was thinking that. Just wasn't sure and I am terrible with names.

 

Unfortunately, names like that get seared into my memory

 

I'm running an older GV unit behind a th350. Still has a Lay**** tag somewhere on it... I remember seeing that name.

 

I have a GV behind a Muncie in my Olds and it is great. I believe the only thing you may want to check is the final gear and tire diameter from the donor vehicle. If the GV tag is still on it GV should be able to decipher all you will need to get it up and running on your vehicle. Joe

 

Wouldn't it be easier to sell off the GV unit and use a 700R4 or 4L60 with a lockup converter.[you wont need a controller either]

You really shouldn't have the cruising RPM below the stall speed of the converter which is why the lockup comes into play

 

They usually run 70 to 76% over driven so 3/4 of a crank revolution is one for the drive shaft. Given that if you are running 3000 rpm at 70 mph, engaging the of will drop that to 2100 give or take.

Had a Lay**** unit in an 85 Volvo 940 turbo wagon. It was set up to only engage in top gear, ran off a ****on on the shift knob. But also was canceled on a down shift to third. It also kicked out if you floored the pedal in fourth so to allow the turbo to spin up. 75mph was 2250 on the tach. Added about 4 or 5 mpg on long hauls.

 

GV overdrive is 0.78 ratio

 

I didn't realize it was an OEM option at one time(not as GV, I know). Will have to use my better eyeball when cruising the older yards in the area.

 

So 2 weeks ago at the races you had your GV unit on your plan B car?

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Plan II. Yeah, that made it nice driving 4000+ miles in two weeks. 3.89 rear gears, so it crosses the finish line at 6000 rpm, and goes down the highway in OD at 2500 rpm at 70 mph.

 

So cool!

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