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Old 01-10-2019, 10:54 AM   #1 (permalink)
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Will this WORK???

In another thread I asked why this will not work??

The question of this hour is:

Can you run a add on second overdrive behind a transmission with its own OD gear and run in both ODs at the same time.

The other thread was about:

I was asking about running a 6 and 8 speed transmissions in a 2003 Ford Crown Vic and a 1993 Chevy Van using VERY low gears like 2:26s.

This was a very helpful thread and ran 5 pages and ended with the question: "Did I know about the old Borg Warner 3 speed with OD?"

It was suggested you could mount the Over Drive, a transmission in its own right mounted on the back of a 3 speed stick shift transmission allowing it to be engaged in any of the 3 gears of the front transmission.


It was suggester that the OD unit by its self once removed from the 3 speed could be mounted in back of many automatics used in 4 wheeler cars/trucks using the adaptor for the 4 wheeler take off transmission.

This took me back to in the 90s where I WAS planing on adding a 3 speed with OD behind my then TH400 with a Switch Pitch convertor.

This would have served as a high and low range by using third as high with my low gear rear end (same plan on using a very low gearing) and second as low range.

I would then have 3 auto gears plus the OD making 4 gears in low and 4 gears in high range.

Seemed like a good idea, at that time.

It was very complex set up needing second stick shifter and controls for the over Drive.

Now I felt using a modern 6 and 8 speed again with a very low rear end gears would be the better answer.

But there are a number of problems. With the Ford 6 speed finding a flywheel is impossible. And finding any lower gears than a 2:75 is also very hard. Then rebuilding the rear end is costly unless I do it my self. So the special rear end could cost from $500.00 to $1000.00 for both the Ford and the Van.

Then there is the cost of a good used 6/8 speed autos, installing them: mounts, shifter controls, shorten drive shaft, VSS senders and a electronic controller to replace the missing PCM computer. Est. $2000.00 PLUS.

It still seemed worth it. How?? Because I plan on driving these two cars until either I or they drop dead. And as I can repair them it will most likely have to be me.

But this new old idea make a LOT of sense.

I have two 3 speeds with the heavy duty ODs behind them.

So all I need do is figure out how to mate them behind my two stock transmissions using one of those 4 wheel adapters, move the transmission mount to the mount on the OD's tail, and get a special shorten drive shaft with its own slip joint, hook up the controls for a OD, (a cable an some minor electric controls) and add a VSS sensor to the tail of the old OD.

And I now have 8 gears (by splitting the for suto's 4) and a super low final drive without having to find gears and rebuilding my rear end, or installing whole different transmission.

I also drop a lot of costs this way.

Stock PCMs, Stock transmissions.

And one extra, the OD's free wheeling so I can even hyper mile.

Seems I have come full circle.

Rich

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Old 01-10-2019, 11:38 AM   #2 (permalink)
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Yes, a friend did it in his 40 ford p/u running behind a buick straight 8. 12 forward 8 reverse. Mounts were a nightmare but (joke follows) he could start it put it in gear, go take a shower and have breakfast and not have it leave his really short driveway. Four on the floor AND three on the tree with overdrive knob.

Flywheel for engine, clutch disc of appropriate diameter from trans. pressure plate from engine.

Same process for slush box: flexplate from engine, drill 3 or 4 torque converter holes from tranny TQ. FORDS or CHEVIES are usually the same engine mount pattern across models.

The most important question: is it worth it? The ranger has 10 forward, 2 R, I use 3 mostly.
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Last edited by Piotrsko; 01-10-2019 at 11:40 AM.. Reason: Bad math
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Old 01-10-2019, 12:51 PM   #3 (permalink)
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Quote:
Originally Posted by Piotrsko View Post
Yes, a friend did it in his 40 ford p/u running behind a buick straight 8. 12 forward 8 reverse. Mounts were a nightmare but (joke follows) he could start it put it in gear, go take a shower and have breakfast and not have it leave his really short driveway. Four on the floor AND three on the tree with overdrive knob.

Flywheel for engine, clutch disc of appropriate diameter from trans. pressure plate from engine.

Same process for slush box: flexplate from engine, drill 3 or 4 torque converter holes from tranny TQ. FORDS or CHEVIES are usually the same engine mount pattern across models.

The most important question: is it worth it? The ranger has 10 forward, 2 R, I use 3 mostly.
Well I THINK it will be worth it IF my van gets 20+ MPG On the highway and if my Ford goes from 20MPH to around 30MPG like the Mercury I have before it did.

I really think it will be of more use in the van as a gear spliter, because there are some hills where you cannot pull it up in 4th and third revs the motor too much so you have to slow down for it, splitting third just might work as a good go between gear.

And as my van is a RV and I do not plan on any heavy loads or any towing it should work fine.

Rich
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Old 01-10-2019, 02:04 PM   #4 (permalink)
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Seems a gear vendors overdrive/under drive is the normal, simple, way people accomplish this. They run $3000 new but there are used ones out there like anything else. My van gets up to 30 mpg highway, why not dump the big van and big car and use a minivan in place of both. Then you also save insurance and liscense fees. It cruises the highway as well as a crown vic with a more comfortable seating position, also has literally a ton of payload with the seats removed, and takes full size 4x8 sheets of plywood.
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Old 01-10-2019, 02:35 PM   #5 (permalink)
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Well my Crown Vic Coast me $550.00 and a little sweat in repairing a few things. So at this point I am in around $1000.00 in her, AND I nave a 04 Junker for parts.

It is fairly easy to repair and there are tons of them around.

It drives like a sports car and is fast.

My van carries four, has a bed for two, a cargo hold that can hold 6 to 8 apple boxes, and my tools, a tow bar should I have a major brake down, rides fantastic and can clime the mountain going east from Indeo CA to AZ and stay at speed.(65-70 MPH)

Ones like it are now what is being sold for around $10,000.00 and it is all paid for.

SO spending around $400.00 to $1000.00 make complete sense to me.

And I should have a little 2002 Ford Explorer v6 5 speed auto to use a s puddle jumper. Projected cost out of pocket $300.00.


Rich

PS The one thing I cannot do with any of my cars is carry a 4x8 sheet.

Last edited by racprops; 01-10-2019 at 08:26 PM..
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Old 01-10-2019, 04:02 PM   #6 (permalink)
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Im with you there on the van. My dodge surfer van had the same issues except I ran the bed lengthwise and could haul a 4 x10. Took me many years and bunches of mods to get to 15 mpg. Aero drag was my primary problem. But always had to down shift for hills under 65 mph. 2 kids ended that problem, had to buy the F250 which used to get 25 mpg before they started altering fuel.
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Old 01-10-2019, 04:52 PM   #7 (permalink)
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Quote:
Originally Posted by Piotrsko View Post
Im with you there on the van. My dodge surfer van had the same issues except I ran the bed lengthwise and could haul a 4 x10. Took me many years and bunches of mods to get to 15 mpg. Aero drag was my primary problem. But always had to down shift for hills under 65 mph. 2 kids ended that problem, had to buy the F250 which used to get 25 mpg before they started altering fuel.
Well at least I am at the point you finished at as my Chevy gets 13/14 MPG.

I will be putting a replacement motor with a Tune Port Injection system which is suppose to give 30% more Torque, HP and MPGs so that should give me 4.2 more MPGs getting me to 18 MPG on a good day, and with a special board added to the PCM giving me a lean burn cruse which took 85-90 Camaros from 25MPG to 30/34 MPG I should break though 20MPG and then add in a second OD.....who knows 25MPG???

Rich
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Old 01-10-2019, 10:30 PM   #8 (permalink)
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https://ecomodder.com/forum/showthre...mpg-33961.html

Read the above

You will have better luck with that approach
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Old 01-11-2019, 01:22 AM   #9 (permalink)
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One can overdo it with gear meshes (lossy drivetrain) and too high gearing (can't pull it unless going downhill) or maybe can pull it empty but still too low rpms- out of the BSFC sweet spot.
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Old 01-11-2019, 04:07 AM   #10 (permalink)
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If you slow the engine down too much you fall out of its efficiency range. Even worse yet, combustion and crank shafts harmonics tear up the rod bearings.

Figure out the lowest recommend cruise rpm and gear for that.
Pushing the operating range down to say 1,000 rpm is just going to ruin the engine.

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