getZ Posted January 17, 2006 Share Posted January 17, 2006 Does anybody know how a lokar shifter downshifts? This may seem like a strange request but I want the ability to downshift an automatic one gear at a time. Most drag racing shifters do an excellent job of upshifting but are made to drop right into low gear from high gear. Kind of scary when you only want to drop one gear down while moving at 50mph. The reason I mentioned Lokar is because they look to be the best fit without having to hack up the center console, not to mention the can be made to look almost like a stock manual trans. I have a street bandit but that needs to be mounted way back so park doesn't smack the dash part of the center console. Quote Link to comment Share on other sites More sharing options...
jakeshoe Posted January 17, 2006 Share Posted January 17, 2006 I can't answer your question on the shifter, but typically one of the harshest things you can do to an auto trans is downshift under decel... Quote Link to comment Share on other sites More sharing options...
kcelectronics Posted January 17, 2006 Share Posted January 17, 2006 I have been using a B & M ratchet shifter on my 5.0 C4 trans and down shifting every day for over 20 years, this is the OLD type 1 gear at a time so you cant miss a gear (not sure if you can still buy this shifter) this shifter wont allow you to quickly move into park you must shift 1 gear at a time, the trans has a B & M shift kit fitted (20 yaers ago also) so I m not sure why you would say "it is one of the harshest things you can do~etc" it is less stressfull that a 3000 rpm launch. Chuckie:twisted: Quote Link to comment Share on other sites More sharing options...
getZ Posted January 17, 2006 Author Share Posted January 17, 2006 I'm not babying that tranny. It was built to be run hard. I've seen a few complaints about lokar shifters on other forums regarding skipping gears going up or down. I think, I will end up modifying a b&m quicksilver. Quote Link to comment Share on other sites More sharing options...
jakeshoe Posted January 17, 2006 Share Posted January 17, 2006 I have been using a B & M ratchet shifter on my 5.0 C4 trans and down shifting every day for over 20 years' date=' this is the OLD type 1 gear at a time so you cant miss a gear (not sure if you can still buy this shifter) this shifter wont allow you to quickly move into park you must shift 1 gear at a time, the trans has a B & M shift kit fitted (20 yaers ago also) so I m not sure why you would say "it is one of the harshest things you can do~etc" it is less stressfull that a 3000 rpm launch. Chuckie:twisted:[/quote'] Actually you are incorrect. A 3000 rpm launch is not nearly as harsh on an auto trans as a downshift. The typical auto trans design is designed to make hundreds of thousands of upshifts under power, it is NOT designed to make thousands of downshifts under hard decel. It will do so, but the life of the trans will be reduced, and the internal damage can be catastrophic when it does so. More trans failure are caused by downshifts than upshifts. It is easy to calibrate a transmission to do 1-2-3 upshifts at a dragstrip. It is difficult to get the same unit to also do properly timed downshifts so it doesn't self destruct. You might study a few auto trans fundamentals such as "shift timing" and "one way sprag or roller clutch operation" and "over-running" I'm not as familiar with the C4, but I can tell you on a GM 3 speed auto, a downshift from 3rd to 2nd under hard decel can spell instant death to the intermediate sprag. Quote Link to comment Share on other sites More sharing options...
getZ Posted January 18, 2006 Author Share Posted January 18, 2006 Your theory might be correct, but I know from actualy doing it is not instant death. I had a 70 camaro with a stock turbo 350. I used to down shift all the time 3 to 2 and 2 to 1, racing against one of my friends in what else, but a 240z. I did everything I could to out brake my friends z but never came close. I flat out abused the camaro for 3 years while going to college and the tranny never gave out. This was in Phoenix where we can see temps upwards of 115 degrees in the summer. I'll let you know how the 2004r does. If it breaks, it breaks. I'll take pictures and tell people not to down shift an automatic transmission and we can have this same discussion again. Quote Link to comment Share on other sites More sharing options...
280zwitha383 Posted January 18, 2006 Share Posted January 18, 2006 First thing, I am not a transmission guy. With that said, I downshift my 350th a few times a day in medium to full acceleration. Feels good too! I also have the B&M ratchet shifter but with mine you can lift up either in park or in drive and freely shift to any position in between without ratcheting. IMO, if the tranny was built up a little and has a shift kit it should be fine. I do however try and match my throttle position with where the engine should be once I downshift so as to sync things a little better (make sense?). I will say that with my truck which also has a (stock) 350th I refuse to downshift because it feels quite ugly and I could easily see how it could mess the transmission up because it feels like it slams into place instead of shifting like my other one. Quote Link to comment Share on other sites More sharing options...
jakeshoe Posted January 18, 2006 Share Posted January 18, 2006 Your theory might be correct' date=' but I know from actualy doing it is not instant death. I had a 70 camaro with a stock turbo 350. I used to down shift all the time 3 to 2 and 2 to 1, racing against one of my friends in what else, but a 240z. I did everything I could to out brake my friends z but never came close. I flat out abused the camaro for 3 years while going to college and the tranny never gave out. This was in Phoenix where we can see temps upwards of 115 degrees in the summer. I'll let you know how the 2004r does. If it breaks, it breaks. I'll take pictures and tell people not to down shift an automatic transmission and we can have this same discussion again.[/quote'] Downshifting under acceleration, such as a detent shift (passing gear) is not NEARLY as harsh. As I stated, under decel is what causes failures. I build racing automatics as a side business when I'm not doing "other" type of work. Quote Link to comment Share on other sites More sharing options...
jakeshoe Posted January 18, 2006 Share Posted January 18, 2006 You also have to take into consideration other factors. RPM at the time of the downshift, converter design, trans calibration, etc.. However, A simple look at the design of the trans will show you that you are asking for failure doing 3-2 downshifts from high rpm. The intermediate sprag grounds the direct drum. That is, it brings it to a complete stop. It does so going out of 1st gear into 2nd, and then it "over-runs" when the direct clutches engage as the trans shifts to 3rd. The int. sprag is a notoriously weak point in the GM 3 speeds, especially the Th350. They are known to break when the trans makes an excessively hard shift from 1st to 2nd (i.e B&M shift kits) and the action of downshifting from 3rd to 2nd has the same effect. An 11 lb drum goes from engine rpm to a complete stop instantaneously from 3rd to 2nd. It only goes from approx 80% engine speed to a complete stop when making a shift from 1st to 2nd. Usually there is some cushion on the 1-2 shift from calibration (accumulator system, cushion plates, oil feed passages). There can be some cushion the sprag on a 3-2 shift, IF the intermediate band is in good shape and grab the drum as the clutches disengage, so that the sprag doesn't take a huge hit. When you are decelerating, instead of the direct drum driving the planetaries, the planets drive the drum. You are more than welcome to do whatever you wish with your transmission, I am just warning you what the results can be. Guys who abuse their transmission help me make extra income... I also deal with 200-4Rs. If you don't have the billet forward drum, I would highly recommend you not do a harsh 3-2 downshift either.... even under acceleration... You'll learn the hard way what the weakest point in that unit is. I am running one behind a 427 in a '69 Chevelle. Quote Link to comment Share on other sites More sharing options...
getZ Posted January 18, 2006 Author Share Posted January 18, 2006 It's from bowtie transmissions. I'd have to check what they put in intermediate trannys. Quote Link to comment Share on other sites More sharing options...
jakeshoe Posted January 18, 2006 Share Posted January 18, 2006 The only vendors of the drum I would use in a performance 200-4R build is CKPerformance and PTS. I do not use PTS, although it isn't necessarily that their parts are faulty. Some other vendors use a heat treated drum, which is better, but not a fix. A WOT 2-3 upshift with a locked converter, or a 3-2 downshift with a billet servo can break the forward drum shaft. Even behind a stock type motor. The best bet on a 200-4R is to dual feed the direct drum, but this adds even more stress to the forward drum on the shifts, so necessitates the billet forward drum. If you don't dual feed the directs, it takes tremendous line pressure to keep them alive. Not good for the variable displacement style pump.... Quote Link to comment Share on other sites More sharing options...
getZ Posted January 19, 2006 Author Share Posted January 19, 2006 This is from "Bowtie Overdrives" website: High Performance Street - $1050.00 Our Level Two Transmissions have all the wonderful features of our Level One Transmission, but their built to handle more horsepower and feature firmer and quicker shifts. These units are still quite street able, however, they should be installed into performance oriented cars and trucks. They will handle a steady diet of around 450/500 hp and 400/450 ft/lbs. of torque. This Level Transmission is definitely a huge step up from what the popular brand name companies offer (according to their descriptions) and they still charge more! We have sold thousands of this Level Transmission over the last seven years with tremendous success. They have proven to be very reliable and tough in serious street performance vehicles. Our Level Two Transmissions feature all the components and modifications built into our Level One Transmission plus the following upgrades: ? New overrun and low/reverse sprag clutches. ? Our own custom machined billet servo with 11% larger surface area than Grand National servos. ? New hardened steel stator shaft. ? Upgrade to a ten vane pump rotor with new rotor, vanes, slider, "O" ring, seal and rubber spring and rotor guide. Thirteen vane pump is optional at no extra charge. ? Hardened steel pump guide rings to prevent breakage in severe high rpm operating situations. ? Main boost valve is upgraded to a .500" main boost valve and our oversized low/reverse boost valve produce higher operating pressures for firmer, quicker shifts and better clamping pressures in all gears. ? Reprogrammed for more aggressive shift timing and feel. http://www.bowtieoverdrives.com/catalog/catalog_inc/viewitem.php?ITEMID=12 Quote Link to comment Share on other sites More sharing options...
jakeshoe Posted January 19, 2006 Share Posted January 19, 2006 That trans contains what I would consider a minimum rebuild. It doesn't even mention an improved forward drum. If it doesnt have it, it won't take 450 lb ft for very long. If you haven't purchased it yet, I would look elsewhere. For more goo dinfo on the 200-4R I would look on the TurboBuick website.... or ask around. PTS, CkPerformance, Century Trans, DynoTech, those are names I would be looking into. BTO doesn't have a great reputation with the 200-4R. Quote Link to comment Share on other sites More sharing options...
280zwitha383 Posted January 19, 2006 Share Posted January 19, 2006 Ah, I don't downshift to slow down not only because I don't like doing that to a transmission but I don't like the thought of stretching out rod bolts because of the sudden reverse torque on them (don't know if that's factual or not but an old hotrodder told me that and it makes sense). Anyway, that I don't recommend. Quote Link to comment Share on other sites More sharing options...
jakeshoe Posted January 19, 2006 Share Posted January 19, 2006 Downshifting under accleration is not a huge issue. Calibration comes into play, but since the drum continues to drive the planets, there is MUCH less shock to the sprag. The trans is designed to make a 3-2 downshift under accel on it's own. I downshift under acceleration all the time. No worries there. Quote Link to comment Share on other sites More sharing options...
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