Well, I'm doing my homework, in advance, about adding an overdrive to my next cruiser project. (might be a '67 VC)


The drivetrain is already in hand, 572 Cadillac (bored and stroked) a TH 400, short tail BOPC trans, with shift kit, and a Ford 9 inch, disc brake, rear axle on bags. (R&P sets available from 2.42:1 to 6.54:1) The big draw is diesel style torque at low RPM's. (1500 RPM @ 70 MPH cruise...)


I have been net surfin' and read all the archive post's I can find, in this and other subforums, digested all the info about Gear vendors, (too much money and has features I don't need) Richmond/Nash, Tremic manuals, (I just don't want to row a gearbox around town) and the 200R4/ 700R4/ 4L80E (would, more than likely, turn out to be as pricey as the GV unit and not as tough)


No one has talked about adding an auxillary gear box between the trans and the third member. Either coupled/bolted to the tailshaft of the TH400 or frame mounted, stand alone in the driveline. I have been searching for an old "brownie box" style 2 speed, shiftable on the fly, (syncro, constant mesh or planatary style, overdrive box. Most are either way to heavy duty or out of my price range.


I know several different styles of 2 speed boxes are used in agricultural machinery, oil field machinery and others. Seems to me that SOMETHING out there could be adapted, I just haven't found it yet. With all the collective wisdom hearabouts, this oughta be an easy one...


Let's bench race this and figure it out.


Thanks in advance, for all the help, Paul

 

Great minds think alike. I've thought about the same issue for a couple reasons. There's been the OD 4 speed Muncie. You already know about the gear vendor OD. There are transfer cases with selectable gears but are huge and set up for 4wd. The marine industry has some planetary gear units, but they are always engaged.
Honestly, have you looked at a 4L80? Not entirely sure if it can be adapted to the caddy motor. TCI(?) even has a built 6 speed version of the 4L80. Might be your best bet without getting exotic or bolting in something the size of a refrigerator.

 

With the torque a Cad 572 would throw down, don't with anything but a TH400 or a 4L80E. You looking around $2000 to start for a 4L80E plus a $500 controller.

 

No matter which way you go, it's not gonna be cheap to handle all that torque out of that monster. Might as well just go with something that has been proven to work with that much power.

I would do a th-400 and Gear Vendors OD.

 

I agree with 70cutty the GV is rated to 1200 hp and guaranteed for 2 years even if you race it. I think the cost will be the same for that as the 4l80e with stand alone comp. maybe less.

 

You need a Turbonique Drag Axle!

 

OK, that has to be one of the coolest things I've ever seen.

 

Check out the other vids on YouTube for a blast from the past. Those things were downright scary.
Captain McClure in his go cart would typically beat everything he went up against, 150mph in a go cart in the quarter mile!

 

That's what a Gear Vendors is.

In any case, do you REALLY think that the custom machine work needed to do this will cost LESS than an existing product?

And just so I have this straight, you've got a custom built 572 Caddy motor, and you're trying to pinch pennies on the trans?

 

First of all, thanks for all the fast reply's. I intended this as a bench racing topic, so lets keep it going 'till we get it figured out.


I am familiar with the Gear vendors offering, it would be ideal for my application, except for the $2500.00 start up, plus the required modifications.


I found, with great joy, that the Hone o drive unit (from the '60's) is now being produced again. That's the one that replaces the pinion carrier on a Ford 9 in. (I have several MK 4 & 5 units) The reality is the $3400.00 start up is, again way out of my budget.


I found several 2 & 3 speed "brownie box" units, in my price range, but they are way too big, physically, to fit in the space available. Either one would be bullet proof and easily adapted to a pick up truck/tow rig, (Lot's of gear sets are available to mix N' match) just not gonna work in a lowered 'wagon.


As far as the various 4,5 and 6 speed autos, anything with a reasonable chance of survival in my application, starts around $5000.00 with the required control box and wiring harness.


The thought of rowing a manual gearbox, behind that torque monster, is not at the top of my list of fun things to do.


I want to find an aux gear box, that can be easily mounted up under a sedan or 'wagon to make a street beast/ground pounder useable as a daily driver/ tourer, without breaking the bank, idealy, under $1500.00.


JOE: not to put too fine a point on it, but, I'm not pinching pennies, I suppose I could throw 5 or 6 thousand dollars at my cruiser,and have it done this weekend, but I would rather use my old school engineering and hot rodding skills to, perhaps light the way for others, That, and I'm really just a CSOB at heart...


Pay no attention to the Bridgeport, the Lathe, the Shaper, the MIG and TIG welders and various other machine and hand tools, behind the curtain...that's just junk left over from my day job, as a master millwright.


Thanks again guy's, you too Joe. Rollin' Rollin' Rollin.


Paul

 

Common sense says that if such a beast existed, it would be common knowledge in all the forums (fora?) and magazines. Any integral box will require an adapter like the GV, plus the appropriate output shave coupler, plus the appropriate driveshaft, etc, etc. Any divorced box will require a custom crossmember and TWO custom driveshafts. Either choice will require floor pan mods.

Since the mind reading thing STILL isn't working, it's kinda tough to know your fabrication skills or available tools and equipment. Suffice to say that 99% of the people who ask questions like this have absolutely no clue as to what's involved in making something like this work. The fact remains that even if you value your time at nothing, you'll spend as much or more than using an existing trans or OD setup. You just won't realize it since the expenses take place over a period of time instead of writing a single $2500 check. Personally, I enjoy fabricating stuff like this myself, but I do it for pleasure. I don't kid myself that I'm saving money. Considering how much you must have in all the custom machine work in that motor, I fail to see much difference between a $2500 GV or built 200-4R and a $1500 one-off that may or may not survive. As you correctly point out, a low-cost add-on overdrive that will fit doesn't exist. You are far from the first to consider this. Use your machining skills and tools to start making one - you'll have a lot of customers. You'll also find out that it won't be any less expensive than the GV if you want to make any money.

 

The shift on the fly seems to be the biggest issue that adds to the complexity and expense. I'm not sure how the GVO works internally, but betting it's sort of an automatic transmission unto itself.
It did occur to me that a cone clutch used in Mercruiser outdrives might be a simple mechanical means to couple either direct drive or a simple planetary OD. Although it would then become part of the power transmission of the engine. That means expensive tailshaft machining to mate to the trans. The alternative would be a divorced transfer case type mount. But this would require extra crossmembers, 2 driveshafts, etc. Probably not practical.
A unit that mounts to a 9" ford rear might be practical though....hmmmm.

 

Back in the 80's there was a company that mated two normal transmissions together and made six speeds out of them. At the time their specialty was two TH400, one without a bell housing or torque converter. It had an adapter obviously. Nowadays six speeds are common and much more compact and practical.

 

The GV is simply a planetary gear set, just like those used in an automatic trans. I'm not sure of the clutch mechanism used, but it likely isn't complex. Other add-on OD units work the same way. Volvo had a factory planetary OD in the 1970s that is very similar to the GV unit. I doubt it is up to handling a 572 cu in Caddy motor.


Ford offered a two speed rear axle on the Cougar in 1970. It is EXTREMELY rare, as you might imagine. There was also a Hone-O-Drive unit that mounted directly onto the Ford 8" and 9" axles. Looks something like this:



More info is available here.

 

You mean I'm only 40 some years behind in that idea?
Not bad for me.

 

Well, technically, they've only been out of production for about 30 years or so...