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Modifying Full Throttle Upshifts BW M12 |
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farna 
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Moderator Lost Dealership Project Joined: Jul/08/2007 Location: South Carolina Status: Offline Points: 19686 |
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 Posted: Nov/29/2021 at 4:16pm |
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Correct, but the D2 position was the "first" D position (right after Neutral). Most people unfamiliar with the trans pull it into that position and assume they have a two speed trans. The "middle" of the forward drive ranges shifts all three gears. D2 wasn't intended just for slippery surfaces, but was intended to be the main forward drive position, with D1 used only on hills or when loaded. The idea was to start in a higher gear and let the torque converter get you started so the car would up-shift to high as soon as possible. It was supposed to be an economy measure, but only if you start slow. If you start quickly (just about have to in today's traffic!) it's better to pull it into D1 all the time. The engine will work a little less getting up to speed, and economy will actually improve over trying to get up to speed quickly by starting in second. There is a big difference in the way people who came up in the 40s and early 50s drive and the way we drive now! Most don't realize how different people used to drive during different decades. When cars first started hitting the road in the early 1900s you had to be part mechanic, and if you drove 50 miles in a day you were driving a lot! Most people drove no more than a couple hundred miles a week, if that. 10,000 miles would wear half the parts on a car out at that time! Even in the 60s 100K on a car meant that it was pretty much worn out and it was hard to get much if you traded it in or tried to sell with over 100K -- I remember my father and grandfather stating that their car had 80K on it -- time to start looking for another! Now 200K is just good broke in, you have at least another 100K to get out of it! My 2003 Toyota Tundra work truck is a bit beat up now (I do home repairs out of it, so always hauling something!), but it has 264K miles on it and shows no signs of slowing down. Only regular maintenance items done to it. Might have to replace the power steering rack or pump soon... I have to put fluid in it every couple weeks now (I average 250-300 miles a week). Both are original to the truck, never replaced! |
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Frank Swygert
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george w
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Joined: Jan/27/2013 Location: New Jersey Status: Offline Points: 2899 |
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Posted: Nov/29/2021 at 5:19pm |
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Frank, I can’t speak for AMC cars built before the 1967 model year but according to the owners manual for my 67 Ambassador ( which I bought new ) D-1 is the intended primary driving range for best economy and performance.. The manual suggests using D-2 range when starting out on slippery surfaces. As for the position of the D-1 and D-2 ranges on the quadrant all I can say is that all Ford Cruise O Matics used the same placement for the primary , all 3 forward speeds, range. That is the position just to the left of L range. Cruise O Matic did not always use the D-1 and D-2 notations. Instead they had two “dots”. The D-1 range was designated with a large dot with a green center and the D-2 range had a smaller white dot to it’s left. I grew up with a lot of Ford products in the late 50s to mid 60s so I was quite familiar with the Cruise O Matic quadrants. IIRC, Cruise O Matic was introduced in Ford cars in 1958 and at that time the quadrants were marked D-1 and D-2. I believe Ford went to the “dots” sometime in the mid 60s.
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Long time AMC fan. Ambassador 343, AMX 390, Hornet 360, Spirit 304 and Javelin 390. All but javelin bought new.
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Buzzman72
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Joined: Sep/15/2009 Location: Southern IN Status: Offline Points: 2725 |
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Posted: Nov/29/2021 at 6:25pm |
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AMC went to the Borg-Warner automatic beginning with the push-button setup in 1958. The '57 automatic was the "Flashaway" Hydramatic built by GM, so the "Flash-O-Matic" name for the Borg-Warner was meant to be a subtle change. Sometime between the '54 Hornet's brief use of Borg-Warner's Detroit Gear DG-200 [after the Hydramatic plant burned in Ypsilanti], designed jointly by Studebaker and B-W, and the debut of the Flash-O-Matic, BW ash-canned the lockup torque converter.
When I got my drivers license in 1970, before I got my '57 Rambler 20-series on the road I drove my dad's '61 Rambler Classic with the 196. It would hold L range to 60 MPH if you floored it, but not upshift until you selected a different button. In D1/D2, the car still topped out at about 90, which was sufficient for a new driver with a high lead content in the right foot. [The '57 Rambler with the 250 V8 and Hydramatic would top out at 120 MPH @ 6000 rpm, and would do it until you ran out of road to run that fast.] As a teenager in that '61, I primarily used the D1 position. Dad primarily used D2. Gas was 32.9 cents a gallon then for the name-brands, and so we never paid that much attention to whether my way used more gas. Edited by Buzzman72 - Nov/29/2021 at 6:28pm |
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Buzzman72...void where prohibited, your mileage may vary, objects in mirror may be closer than they appear, and alcohol may intensify any side effects.
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tomj
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Joined: Jan/27/2010 Location: earth Status: Offline Points: 7553 |
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Posted: Nov/30/2021 at 12:02am |
Lol, the owner's manual for my 1960 American suggests using D2 for most driving, and D1 when you need extra power! This was a flathead with the cast-iron M8 transmission -- so yeah, you might want "extra power"! |
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1960 Rambler Super two-door wagon, OHV auto
1961 Roadster American, 195.6 OHV, T5 http://www.ramblerLore.com |
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WesternRed
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Joined: Aug/03/2010 Location: Australia Status: Offline Points: 5808 |
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Posted: Nov/30/2021 at 2:35am |
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I reckon I used to be able to hold 2nd to higher RPM, but now it does the auto upshift around 5200 as mentioned above, maybe the governor came unstuck or something on the last rebuild.
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I've finally given up drinking for good...........now I only drink for evil.
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DAMX
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Joined: Nov/13/2017 Location: Silicon Valley Status: Offline Points: 195 |
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Posted: May/21/2022 at 12:28pm |
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Manually shifting is the solution, but there is 1 remaining problem. I seem to be near stopped to get the transmission down into 1st with the selector in 1st. At a stop 1st can be selected. Once you are moving a bit selecting 1st does nothing, but keeps the transmission in 2nd. Since I have a 2.87:1 final drive 2nd is too high until the car is going about 45mph. It's a slug in 2nd between 10 to 45mph, but quite impressive from a stop (the tires will smoke halfway through 2nd). Could this be a governor problem? Thanks!
Regards Dono
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george w
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Posted: May/21/2022 at 1:54pm |
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What your describing is normal, but not desirable, with the factory settings for the trans. pressure. Raise the trans. pressure by cranking up the vacuum modulator several turns and then do a road test. Shift points will raise as will shift firmness. You’ll know if you go too high as the shift points will be too high or not at all. Expect after raising the pressure that you’ll notice a clunk with the 3-1 coasting downshift.
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Long time AMC fan. Ambassador 343, AMX 390, Hornet 360, Spirit 304 and Javelin 390. All but javelin bought new.
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PROSTOCKTOM
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Joined: Jun/20/2010 Location: Indiana Status: Offline Points: 2458 |
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Posted: May/21/2022 at 2:56pm |
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While I am not familiar with a BW12 transmission internals I am familiar with a lot of other transmissions and how the operate. Playing with a modulator is only going to get you so far on raising the shift points. To get the rpms you want you'll need to play with the springs in the governor.
I had a Ford C4 that we played with the spring in the governor until it would shift 1-2 under WOT at 5600 rpms and 5400 rpms on the 2-3 shift. We spent weeks and weeks trying to get the rpms up on the 2-3, but finally my friend that owns the transmission shop told me that's as good as you're to get. However like the others have already stated if you want to do high rpm WOT shifts and expect it to live you probably need to remove the BW12 and replace it with a different model transmission (727, TH400). While I have both in my opinion the TH400 is the easiest from the kickdown standpoint since it uses a switch and you don't have to deal with all the linkages require on a 727. Good Luck, Tom
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Molnar Technologies Full Service Dealer - Crankshafts & Connecting Rods
1969 AMC Rambler Rouge Race Car 1974 AMC Hornet Hatchback, Wally Booth Outlaw Nostalgic Pro Stock Race Car Project |
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george w
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Posted: May/21/2022 at 4:14pm |
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Adjustment of the modulator is external and relatively easy. All you need is a very small and short handled flat tip screwdriver. I’d suggest getting one of those cheapo jewelers screwdriver sets. Take the largest flat tip from the set and cut the handle down to about 3/4”. Pull the rubber hose off the back of the modulator and slide the screwdriver down inside the nipple to engage the adjustment screw clockwise. You’ll be tightening the screw against spring pressure. Crank it in two or three turns and do the road test. There’s no reason to get inside the transmission and make any changes in the governor. The transmission determines the shift points by comparing the governor pressure to the modulator pressure. When the modulator pressure exceeds the governor pressure the upshift occurs. You’re raising the modulator pressure. If you need a higher shift point than about 5000 rpm then this won’t do it for you.
It may be necessary to loosen the rear trans mount and drop the trans. crossmember about an inch to fit the screwdriver in. This is an easy ‘fix’ and requires nothing other than about an hour or less of your time. You’ll want to adjust the setting so that the 1-2 and 2-3 up shifts occur at about 4900 rpm if you have a stock cam. As a side benefit you’ll extend the transmission life, especially the life of the front band which controls the 1-2 shift. There’s no need to get into the complexity of messing with the transmission’s internals or the expense and effort of a transmission swap if you’re planning on simply doing typical street driving. Edited by george w - May/21/2022 at 4:21pm |
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Long time AMC fan. Ambassador 343, AMX 390, Hornet 360, Spirit 304 and Javelin 390. All but javelin bought new.
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farna
Supporter of TheAMCForum
Moderator Lost Dealership Project Joined: Jul/08/2007 Location: South Carolina Status: Offline Points: 19686 |
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Posted: May/21/2022 at 7:05pm |
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The trans won't shift into first over a certain speed (20 mph or so) for safety reasons. Dropping into first could damage the trans or slow the rear wheels suddenly, having the same affect as locking the rear brakes and could cause one to lose control of the vehicle. All the Borg Warner autos have that feature -- I'm pretty sure even the modern derivatives do, like the AW-4. Once speed drops below the threshold speed (I'm not sure it's 20 mph... but close) it will drop down into first gear while moving. |
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Frank Swygert
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george w wrote: