Author Topic: Inline overdrive gearbox sources?  (Read 6008 times)

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Offline mikeames

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Inline overdrive gearbox sources?
« on: September 28, 2011, 01:21:34 AM »
I'm wondering if anyone makes a manual gearbox that I can mount inline behind my manual trans in my truck that would give me another higher gear...or overdrive. It seems like this should be a simple thing...just a two speed gear box...push in the clutch and switch from 1:1 to overdrive.
I've looked at Gearvendors...they seem way over complicated and way too expensive for me.
Seams like some of the older larger trucks had something similar to what I'm talking about...I'm hoping to find a wrecking yard item I might be able to make work.
Basically I need better mileage out of my '84 W350 with TBI'd 416 stroker motor. It's got plenty of torque to pull higher gears, but the RPMs are way too high at freeway speeds. I could change both rear-end ratios...but that's spendy too.
Any thoughts?
mikeames@clear.net
1984 W350 4X4 Crew-cab, 360>416Stroker w/ TPI fuel injection (AFI), Hedman headers, Magnaflow Performance mufflers w/ custom pipes, NP435, NP205, D60's at both ends, Rear LS, Custom Mikco bumbers and headache rack, Power leather buckets up front, Competition Orange paint.

Offline ToxicDoc

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Re: Inline overdrive gearbox sources?
« Reply #1 on: September 28, 2011, 01:29:03 AM »

Any thoughts?

Unless you do find something like what you're describing (I wouldn't know about the older truck applications), the solution is  pricey - gears, convert to 5spd (NV4500), Gear Vendors, or even go diesel.
'85 W150 SB, 408 stroker, Magnum manifolds, Performer RPM, 670 Truck Avenger, HEI ignition, Auburn LSD 9.25 and '82 D44 (non-CAD) with 3.55/3.54,  NV4500/NP241

Offline Elwenil

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Re: Inline overdrive gearbox sources?
« Reply #2 on: September 28, 2011, 01:50:46 AM »
He's talking about a Brownie Box, which I think were usually a lower split gear rather than an overdrive gear.  They are very hard to find these days and only fit a few transmissions.  For overdrive the cheapest route is to simply swap in a 5 speed.  Otherwise a Gearvendors or US Gear OD add on is about your only choice.
L.Clemons

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Offline 340SHORTY

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Re: Inline overdrive gearbox sources?
« Reply #3 on: September 28, 2011, 01:21:09 PM »
I know years ago Borg Warner offered one, but that was 35 years ago..

where would a person look for this Laycock OD?? 
Your truck info goes here...

Offline cjohhny

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Re: Inline overdrive gearbox sources?
« Reply #4 on: September 28, 2011, 01:36:27 PM »
I know years ago Borg Warner offered one, but that was 35 years ago..

where would a person look for this Laycock OD?? 

Sounds like your local junkyard that has a few Volvo cars in it might be a good place to start,
1982 W350 Club Cab NP435 4x4 - just an old work truck, great for hauling and towing stuff.
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Offline ChrisKD

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Re: Inline overdrive gearbox sources?
« Reply #5 on: September 28, 2011, 01:40:35 PM »
I know years ago Borg Warner offered one, but that was 35 years ago..

where would a person look for this Laycock OD?? 

1960's - 1980's Volvo cars (some 90's too, i believe) It is commonly found behind Manual Transmissions, although i've heard it was available behind Autos too.

I once read in a magazine, that the Laycock overdrive was popular in certain drag racing circles, for a dual purpose car (street/strip) to offset low gear ratios for highway driving, while being strong enough to hold together for drag racing too.
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Offline 340SHORTY

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Re: Inline overdrive gearbox sources?
« Reply #6 on: September 28, 2011, 01:46:19 PM »
just talked to the rep at MO.  he said the Volvo OD was only rated to about 180 HP.  the adapter to put it behind my NP 435 is 900.00 ....
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Offline ChrisKD

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Re: Inline overdrive gearbox sources?
« Reply #7 on: September 28, 2011, 01:54:05 PM »
just talked to the rep at MO.  he said the Volvo OD was only rated to about 180 HP.  the adapter to put it behind my NP 435 is 900.00 ....

J-Type or P-Type?

I'm pretty sure Leon's Turbocharged 440 W350 is putting out at least 3 times that number
76 Ramcharger 318/727/203
48 Dodge Pickup
83 Scamp GT 2.2 Turbo AWD
92 Dakota 5.2/518/231
84 PW50 273/727/100/203
74 Duster 6-71 Blown 340/833/D60
73 Duster 340/727/8.75
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Offline impish

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Re: Inline overdrive gearbox sources?
« Reply #8 on: September 28, 2011, 08:33:13 PM »
any try the ranger that goes in front of the trans?
89 W350 5.9 tbi/727/D44/60s 
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Offline cragdweller

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Re: Inline overdrive gearbox sources?
« Reply #9 on: September 28, 2011, 11:00:45 PM »
There is a much cheaper way of adding a overdrive like the Gearvendors unit without the high price, I have a P-Type Laycock overdrive from a Volvo 740 Turbo mated to the rear of the NP-205 in my W-350.

The P-Type Laycock DeNormanville is the same unit Gearvendors now builds and can be added for under 1k, Maximum Overdrive sells the adapters and input shafts to use a J or P type Laycock overdrive that can be found in Volvos for cheap, the J-type is very common, Volvo used more of them than all other makes put together. The P-type is stronger but harder to come by, still cheaper than a Gearvendors unit.

Seven forward gears is nice, second over and third over are quite useful while towing, or just showing off by going through all seven gears as fast as I can {lol}

The Laycock shifts into overdrive at the flip of a switch, on power or not it does not really care though backing off the throttle is a good idea ;)

The control box the Gearvendors unit uses is not needed, only a switch and a pair of relays to lock out the overdrive in reverse and while in four wheel drive.

This is great stuff.  I know alot about cars (or at least I thought I did :)) and I've never heard about this.  I learned something today.  Great stuff.  how much length does this unit add behind a 205?
1975 Plymouth Trail Duster Sport.  440/727, 203/205 doubler, Dana 60 front and 70 rear.  Still under construction...

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Offline Heinrich_Ram

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Re: Inline overdrive gearbox sources?
« Reply #10 on: October 17, 2011, 08:38:59 PM »
I thought about getting one years ago but they didn't offer it for a Dodge ???

x2 pretty sure you gotta have a muncy tranny dont you?
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Offline Elwenil

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Re: Inline overdrive gearbox sources?
« Reply #11 on: October 17, 2011, 08:49:28 PM »
A Ranger is the same as the Brownie box I mentioned above.  They are most commonly found for B/W transmissions in my experience, but do exist for GM/Muncie and New Process, though they are ridiculously rare and impossible to find parts for.
L.Clemons

1988 Ramcharger-Mil-Spec AW450 Project-318EFI-NP435 4 speed-NP205 Transfer Case-Front & Rear Dana 60s-Braden Wormdrive Front Winch
I do not like shortcuts.  Any job worth doing is worth doing right.

Auribus Tenere Lupum

 

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