Brad-ManQ45 Posted October 18, 2006 Share Posted October 18, 2006 Hi guys. A lot of cars out there have either paddle shifters or a shifter position that 'toggles' either up or down one gear if put into a 'gated' position. I have a question about these transmissions: I know for instance that usually, one of the worst things you can do to a transmission is downshift it manually. Have the manufacturers made changes to the transmissions that have the above capabilities, or does the powertrain control module prevent the shock loads from the negative effects of downshifting through the gears (perhaps automatically speeding up the engine to match rpms)? Hoping ya'll can enlighten me. Thanks, Brad Quote Link to comment Share on other sites More sharing options...
Dudeboy Posted October 28, 2006 Share Posted October 28, 2006 I have been reading and researching the options and issues since Twist machines came out with there paddle shifters. A buddy mine has it (4L60E/LT1), and from what he tells me it is control by the module, transmission controller and the programming of the software. If you have not check them out yet, go to http://www.twistmachine.com. I am doing a LS1/4L60E swap with paddle shifters, I am looking to be at the stage by spring 2007 God willing !! Quote Link to comment Share on other sites More sharing options...
Guest Mike Posted October 28, 2006 Share Posted October 28, 2006 Nice... but a bit pricey. Quote Link to comment Share on other sites More sharing options...
mario_82_ZXT Posted October 28, 2006 Share Posted October 28, 2006 Is this such a good idea? I can't remember if it was here or on zcar.com about this huge thread on auto's and what happens when you downshift them to decelerate. Apparently it puts a lot of strain on clutches and the inner workings and greatly reduces it's life span. This is different then downshifting and flooring it, as apparently they are designed to do that (like through the kickdown switch). Mario Quote Link to comment Share on other sites More sharing options...
Dudeboy Posted October 28, 2006 Share Posted October 28, 2006 I agree hard deceleration is hard on any tranmission (stick or automatic). I am no expert with padddle shifters, I watch and took notes as a corvette buddy of mine installed on his camaro project. It is very slick and in a GM transmission 4L60E and the newer GM transmissions it is plug, play and programming. The great thing about it is you can turn it "on and off " at the flip of a toggle or rocker switch. Quote Link to comment Share on other sites More sharing options...
Brad-ManQ45 Posted October 29, 2006 Author Share Posted October 29, 2006 Thanks for replying guys. I have picked up that some of the imports actually match rpms on some of the cars/SUVs that have the sport shifters that toggle. It is my understanding that the overrun clutches take a beating when downshifting manually. My question was hopefully aimed at tranny experts that can answer whether or not it is possible to do this without harming the tranny. I am hoping that the combination of electronic tranny control and MS will allow manual downshifting with few downSIDES... Quote Link to comment Share on other sites More sharing options...
jakeshoe Posted October 30, 2006 Share Posted October 30, 2006 It somewhat depends on the specific transmission, but deceleration downshifts while above the converter stall speed or with a locked converter are rough on an automatic transmission. I'm assuming you are looking at using a 4L60E. As mentioned, the over-run or coasting clutches are not used in OD, but are used in 3rd, so if you do a manual downshift from 4th to 3rd under decel, these two very small clutches will not last long. On a 3rd to 2nd downshift can be cause additional wear on the 2nd band, but this shouldn't be a huge issue if it's built right. You would want to be sure the trans was properly accumulated so that the 3-4 clutches released quickly so they aren't dragging as the band applies on the downshift. Then on a 2-1 downshift, the low sprag will lock, this is pretty brutal to the sprag (actually a roller clutch). IMO the 4L60E isn't the unit to use for a hi-perf setup. Quote Link to comment Share on other sites More sharing options...
badjuju Posted October 31, 2006 Share Posted October 31, 2006 Is this such a good idea? I can't remember if it was here or on zcar.com about this huge thread on auto's and what happens when you downshift them to decelerate. Apparently it puts a lot of strain on clutches and the inner workings and greatly reduces it's life span. This is different then downshifting and flooring it, as apparently they are designed to do that (like through the kickdown switch). Mario my transmission wants to explode everytime i downshift... it does okay from 3rd to second, but unless i've been stopped for ~5 seconds, 2nd to 1st gives a clunk that would scare any car owner. Quote Link to comment Share on other sites More sharing options...
badjuju Posted October 31, 2006 Share Posted October 31, 2006 Also, a guy on turbobricks.com made his own, I'm on a reference computer at UW right now so I can't go to a .com site or I'd link you. If i remember right though, his car is the one with the big intercooler on the front page. Quote Link to comment Share on other sites More sharing options...
lesd Posted November 21, 2006 Share Posted November 21, 2006 What auto tranny would you recommend to put behind a turbocharged LT1 in a 240z ? I am using an after market engine management system, and it won't control a 4L60E . I can get an after market transmission controller, but I'd rather not pay $700 for that if I don't have to. The car will be street drive, with rare 1/4 mile track tests. I must have overdrive. Thanks, -Les IMO the 4L60E isn't the unit to use for a hi-perf setup. Quote Link to comment Share on other sites More sharing options...
jakeshoe Posted November 22, 2006 Share Posted November 22, 2006 If you are planning on doing alot of downshifting as in roadracing, auto-crossing, then I would use a manual trans. TKO or similar. If you want a bulletproof automatic then the 4L80 is a good option but pretty large in a Z car. You could have a 200-4R built up to about the 600 HP level. Above that and I tend to suggest a 4L80E. Quote Link to comment Share on other sites More sharing options...
lesd Posted November 22, 2006 Share Posted November 22, 2006 Thanks for the response, Jake, Do the non-electronic manual shift kits for the 4L80 have any mechanism to soften the shifts for light throttle shifts? Seems like you would at least need a vacume input, otherwise the light 240Z would shift way too hard. Anyone know how hard of a fit the 4L80 would be in a 73 240Z? I wish I had a description of the PWM signaling needed to control the trannys, I am pretty handy with micro controllers for running stuff like that. -Les If you are planning on doing alot of downshifting as in roadracing, auto-crossing, then I would use a manual trans. TKO or similar. If you want a bulletproof automatic then the 4L80 is a good option but pretty large in a Z car. You could have a 200-4R built up to about the 600 HP level. Above that and I tend to suggest a 4L80E. Quote Link to comment Share on other sites More sharing options...
jakeshoe Posted November 22, 2006 Share Posted November 22, 2006 Les, I'm not up on the MegaSquirt but about a year ago they were working on a MegaShift add on. I think it has become a more universal deal, but soem have used it to control trans. I probably have any PWM info you need to control the trans on hand here (literally less than a foot away) in my tech literature. The MEgaSquirt BB would likely also have it. Anyway, there is a kit to provide full manual shifts for the 4L80E without a controller and it uses a vacuum modulator to control line pressure instead of the Electronic pressure control solenoid. The EPC is removed and replaced with the modulator. This is available for both the 4L80 and 4L60E. The electronics of a trans aren't overly complex, not nearly as complex as the engine control. A trans controller needs RPM signal, throttle position signal, output shaft signal, and Park/N/Drive to operate. Internally they have a switch and temp sensor, that measures the fluid temp, and has small individual pressure switches that let the controller know what circuits have pressure and which don't. They also have the two shift solenoids that actually force the shift, and the EPC solenoid to control line pressure. They then have the torque converter control solenoid which is now pulse width modulated so that it doesn't act so much as an on/off, but can control the apply rate of the converter clutch so it doesn't feel like an additional shift. I actually prefer a more firm TCC engagment and for reliability feel it shouldn't be "slipped", but it should also have a controlled engagement, but this can be controlled through orificing and doesn't have to be done through the controller. Quote Link to comment Share on other sites More sharing options...
lesd Posted November 24, 2006 Share Posted November 24, 2006 Thanks, I did see the megashift info, it does look promising. I don't think they are out with a design yet as far as I can tell. Maybe if I had the signal timing diagram with the signaling sequences, I could implement it myself. Heck, I'll bet I could sell a few at a $300 price or so. The parts would cost about $80 I would guess. But I'm spread too thin with the car project anyways, sheesh. I noticed that the Grand Nationals used the 200-R4, so with a light car such as the 240Z that *built* trans should be fine, I would think? I want to run drag radials to help with the traction limit, but even those will break free to limit the stress on the transmission to some degree. I want to go with the most bang for the buck, with it still fitting without too much hammering out the tunnel. -Les Quote Link to comment Share on other sites More sharing options...
Armand Posted November 24, 2006 Share Posted November 24, 2006 If you were to downshift in a regular automatic wouldn't the torque converter just slip until the engine's rpm's matches with the cars speed? Is it really that bad? Quote Link to comment Share on other sites More sharing options...
jakeshoe Posted November 24, 2006 Share Posted November 24, 2006 We are mostly discussing late model electronically controlled transmissions that have a lockup converter. A lockup converter acts as a positive link between the engine and trans input shaft, so no the converter won't just slip until the engine speed matches up. A downshift during deceleration is very hard on the trans internals especially if you are above the stall speed of the converter or if it is a lockup type converter. When we "re-engineer" the trans to make firm upshifts under throttle, by installing a valve body or shift improver kit, often-times we are deleting the important accumulation that the OEM engineers designed into the transmission. They didn't just design this into the unit to soften upshifts for comfort. It is for reliability also. Each transmission design has specific reasons that it is harmful to downshift. On a 4L60-E or 700-R4 (same basic design) a downshift from 4th to 3rd under decel will kill the over-run clutches VERY quickly. There are only two small clutches and they weren't intended to be shifting under load clutches. You also have the forward sprag, and on a 4-3 shift, it must relock. It is a known weak point in the trans, it has been known to fail even when doing a acceleration downshift from 4th to 3rd, such as a factory kickdown while going up a grade. They were upgraded to a 29 element unit in the late 80's but it is still a small sprag unit and not intended to be abused. Best bet is to avoid doing decel downshifts, especially from higher rpms. Quote Link to comment Share on other sites More sharing options...
jakeshoe Posted November 24, 2006 Share Posted November 24, 2006 Thanks, I did see the megashift info, it does look promising. I don't think they are out with a design yet as far as I can tell. Maybe if I had the signal timing diagram with the signaling sequences, I could implement it myself. Heck, I'll bet I could sell a few at a $300 price or so. The parts would cost about $80 I would guess. But I'm spread too thin with the car project anyways, sheesh. I noticed that the Grand Nationals used the 200-R4, so with a light car such as the 240Z that *built* trans should be fine, I would think? I want to run drag radials to help with the traction limit, but even those will break free to limit the stress on the transmission to some degree. I want to go with the most bang for the buck, with it still fitting without too much hammering out the tunnel. -Les Les, A stock GN 200-4R isn't all that stout although it is a good unit to stat with, and will work fine in a Z car with the right upgrades, but it will still be at least a $2000 transmission for any type of power (400HP+). Quote Link to comment Share on other sites More sharing options...
lesd Posted November 24, 2006 Share Posted November 24, 2006 So my choices seem to be a well built 200-4R , or the 4L80 with the manual shift kit. ( or an electronic control box ). I have not seen any posts from anyone fitting the 4L80 in the 240. I do want to push the motor as far back as possible with the LT1. Since the distributer isn't the limit, the limit will be the fat case of a 4L80. Would the costs for 500 ft lb torque spec be similar on these two choices? The torque would most likely be the most at the overdrive gear, at speed. Maybe the gear ratios of the 4L80 would be better for the Z ? Thanks for your advice ! -Les Les,A stock GN 200-4R isn't all that stout although it is a good unit to stat with, and will work fine in a Z car with the right upgrades, but it will still be at least a $2000 transmission for any type of power (400HP+). Quote Link to comment Share on other sites More sharing options...
jakeshoe Posted November 24, 2006 Share Posted November 24, 2006 At 500 lb ft, use the 200-4R. It is more than capable of that powr level if you do a quality rebuild with a large 2nd servo, good 2nd band, alto red direct clutches, dual feed the directs, good 10 or 13 vane pump with chromoly rings, and a billet forward drum. Quote Link to comment Share on other sites More sharing options...
jakeshoe Posted November 24, 2006 Share Posted November 24, 2006 At 500 lb ft, use the 200-4R. It is more than capable of that powr level if you do a quality rebuild with a large 2nd servo, good 2nd band, alto red direct clutches, dual feed the directs, good 10 or 13 vane pump with chromoly rings, and a billet forward drum. Quote Link to comment Share on other sites More sharing options...
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