R-7 versus R-10 Overdrive?

[bamfordsgarage]

Hello all

Last fall I was set to install a George Asche R-10 OD in my '47 D25, but backed away feeling I wouldn't have the power to properly use the thing. At the time we were heavily loaded, running a tired engine and fighting the west Pennsylvania hills. Not a good combination.

With an engine overhaul started and planning to travel with a lesser load (and another long drive planned, this time with more flat land) I am again thinking overdrive. In hindsight, I really should have gone ahead with the GA OD and been done with it.

I have the prospect of an R-7 OD and transmission that "looks OK" at what seems a reasonable price, and I am contemplating this setup for my D25. As I understand it, the R-7 is a centrifugal setup vs the electrically-actuated R-10, and somewhat less robust. There would be no kickdown feature and it would not operate in reverse. The unit I am considering has column shift. I am fine with manual engagement only, but uncertain about durability.

Would appreciate any comments from others about the R-7 compared to the R-10 and particularly the suitability of an R-7 for my application.

[1941Rick]

I would go with the R10.....it replaced the r7 for a reason...go with the newer version......as for power you should have plenty as long as you are running 3:9 or 4:10 gears.....I use mine in the city...just put it in second and that is where it stays,,,,kinda fun......

[Dodgeb4ya]

The R7 does have the kick down operation with a throttle kick down switch and relay. The solenoid on the trans is what shorts the IGN points for a few firing cycles and then will kick it out of OD into direct drive.

I have driven the R-7's and think they are a good transmission. They are a lot cheaper too. The rear case housing doesn't wear out like the MoPar R-10's. You need to see what car it came out of-stamped on the drivers side of the case by the shift cover. Also check the input shaft size into the pilot bearing and look at the rear drum yoke for type and size. In my opinion R-10's are way too expensive! Parts for the rear OD section are hard to locate for either ect. If it's (R7) cheap put it in your car and try it out! A wiring diagram for a 1939-1941 Chrysler/DeSoto will show you how it's wired up.

Bob

[greg g]

Grab it regardless of which you choose to install. I believe the ratio is a bit different on the earlier ones, not as much Over, but still worth while.

[Alshere59]

Hello

Well I haven't owned an R 10, I do have an R7 though. So all I can talk about is my experience. Currently running it with a 3.5 jeep rear end. Ohio is fairly flat and I have no problem getting around with a 230 rebuild. When I go to Missouri (Lots of hills around) I just disengage it run it like a normal 3 speed. On the highway it can disengage with the switch for passing or hills. So for me it works. It engages at roughly 28 mph just let off the gas a second. It does take getting used to when parked as it will roll in any gear other than reverse.

Hope it helps.

Al

[suntennis]

Since the R7 does not have a speed sensor, it was my thought that it would or could shift into overdrive at any speed. With R10, it will not go into overdrive until about 27 mph. You will enjoy an OD. If not in hilly area, a 3.9 rear gear will work great.

[Dodgeb4ya]

The spring tension on the centrifical flyweights is what controls the speed the OD cuts in at-about 26-28 MPH. No governer needed. There is a plug you can remove on the OD case to adjust this cut in speed. Normally you would never tamper with this adjustment.

[meadowbrook]

I have an R7 OD from Asche and it was not cheap. I think it cost maybe a couple hundred less than the R10.

I think it is the same level of OD as the R10 (around 0.7). I installed it in my '50 Dodge Meadowbrook, with its original, somewhat tired 230 and a 3.9 rear.

When disengaged the ratios are pretty much the same as the standard 3 speed manual, though mine has a 'fast 2nd gear', which according to Mr. Asche, is a bit taller than stock. So hills are no problem. Also, even with OD engaged, I hardly ever find the need to downshift on hills, though I do live in Michigan

I like this unit because it does not rely on any electrical solenoid to maintain the OD engaged like the R10, so I would think there is 1 less thing to break or burn up and has simpler wiring, On the down side you have more flexibility on an R10 because you can command shifts electrically, while the R7 you can only down shift electrically.

Finally, having a Meadowbrook with fluid drive, I already can't just leave it in gear when parked anyway, so the OD's freewheeling nature is transparent to me, I just need to always have a working parking brake.

[p24-1953]

Medowbrook, are you the other fuid/hydrive w overdrive conversion george did? he made mine 2 years ago and when i was talking to him a few weeks ago he said that in all his years he has only done 2 conversions.

[bamfordsgarage]

Well, this is welcome response and information. Thank you all. BTW my rear axle is 3.9:1 and our local terrain (100-200+ miles any direction) is basically flat. The R-7 is am considering is $500 plus freight from Neil Riddle in WA — not real cheap but less than half a rebuilt R-10.

Dodgeb4ya Bob, "You need to see what car it came out of..." Q: I assume confirming it is DPCD is enough, or does the particular Mopar brand matter?

I am confused about the operation and control of an R-7. What I think I know is this, and please correct or elaborate...

1. There is a T-handle below the dash by which the driver selects whether the OD can operate or is out of the system completely.

2. With the T-handle engaged, the OD will kick in automatically at 26-28 mph through centrifugal flyweights. Q: Must the driver throttle-off briefly to trigger this event?

3. With the OD engaged, stomping the throttle will trigger an electrically-actuated downshift to direct drive, and, simultaneously cut out the ignition to enable this downshift.

4. The car will roll when parked in any gear but reverse. Q: Is this only when parked with the T-handle engaged, or all the time?

5. Power is supplied to the OD unit, there are wires from the transmission to the throttle kickdown and ignition, but no wiring or switches in the driving compartment.

More questions:

When in OD at, say, 40 mph and the car coasts down to below 26-28 mph, does the OD automatically shift into direct? And if so, does the throttle have to be off for this to occur?

Is the throttle kick-down switch carburetor-specific? My D25 has a Stromberg BXV-3.

[Plymouthy Adams]

The rear case housing doesn't wear out like the MoPar R-10's. Bob

for clarity, the R-10 is a Borg Warner unit that a version was made for about every car maker under the sun..

[meadowbrook]

Probably, sounds like the same time frame. He had no R10s at the time. My car had a standard 3 speed with Fluid drive before.

[Joe Flanagan]

Chris, check the Downloads section of this site. There is a great manual on the operation of the Borg-Warner R-10. It should answer your questions. Also, go to the web site for the Imperial Club. They have a great collection of shop literature, including three individual booklets on the R-10.

[Dodgeb4ya]

for clarity, the R-10 is a Borg Warner unit that a version was made for about every car maker under the sun..

Yea, that would be Rambler, Nash, Studebaker, Kaiser, Henry J, Fraiser, Chevy ,Merc, Lincoln and maybe some more.

MoPar R10's had a issue of rumbling wear in the OD case if the oil level was not kept near full. Have replaced quite a few rear cases because of excessive clearance and freeway rumbling.

[bamfordsgarage]

Chris, check the Downloads section of this site. There is a great manual on the operation of the Borg-Warner R-10. It should answer your questions...

Thanks Joe, that was useful information and I am much better informed on the R-10. I don't often think to check the great resources elsewhere on this site.

It would be appreciated if others smarter than me could reply to the questions I raised in my post yesterday AM. I'd like to decide one way or the other soon on this R-7 from NR. Thanks.

[greg g]

So how come Mopar applications are so expensive, and guys at Studebaker Swaps sell them for half or less than Mopar labled ones.

[Young Ed]

Greg its all about rarity and demand. It seems like a lot more of the studes came with OD.

[vanbuskirk]

I have driven 20k+ miles in a P-15 with an Asche 1940 Chrysler OD. Simpler than an R 10 and very dependable. Kickdown is done with an under dash toggle with a reminder buzzer. BUZZZZZZZZZZZZZZ. I installed an R10 in the '54 wagon. I prefer the R7. Simpler. Does not require electricity, except for kickdown. Bob

[Dodgeb4ya]

So how come Mopar applications are so expensive, and guys at Studebaker Swaps sell them for half or less than Mopar labled ones.

MoPar guys are... well.... Stupi...uh I guess desperate! They just pay too much:eek:

[greg g]

Bob VB has made some long trips with his P15 wagon, and he travels with stuff, camping gear, cooler, etc. so his r7 experience I can vouch for as valid.

[Alshere59]

Hope this helps.

2. With the T-handle engaged, the OD will kick in automatically at 26-28 mph through centrifugal flyweights. Q: Must the driver throttle-off briefly to trigger this event?

Yes that is the way it works.

4. The car will roll when parked in any gear but reverse. Q: Is this only when parked with the T-handle engaged, or all the time?

Only when the handle is in the engaged position.

When in OD at, say, 40 mph and the car coasts down to below 26-28 mph, does the OD automatically shift into direct? And if so, does the throttle have to be off for this to occur?

It will disengage as you drop below 28 (YMMV at the exact speed) when you take your foot off the gas to slow down. If it were to drop below 28 on a hill for instance it would not until the gas was released.

Is the throttle kick-down switch carburetor-specific? My D25 has a Stromberg BXV-3.

The "switch" is the same as I understand it, the bracket would need to fit your carb. By the same I mean the switch only needs to be a momentary contact rated for the correct amperage. Basically it just makes contact when you floor the gas pedal, or as mentioned above can be ran on the inside of the car for versatility.

Al

Edited December 14, 2011 by Alshere59

[Young Ed]

The kickdown can also be put under the hood along the throttle linkage. Mopar used that design along with the carb mounted version.

[Frank Elder]

MoPar guys are... well.... Stupi...uh I guess desperate! They just pay too much:eek:

You are actually pretty close on the stupi.....part, brand loyalty seems to cause brain cell loss sometimes:D:eek:you gotta admit when a part is cheaper than usual we sniff around it like an old suspisious dog.

[greg g]

a micro switch mounted in a shift knob is a handy way to approach OD kick in kick down.

[bamfordsgarage]

Thanks again to all who contributed. I've told Neil Riddle I'll take his R-7 and we are just working out the shipping details.