Lockup Converters
04-06-2006, 01:10 PM
#31
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Join Date: Jan 2002
Location: Bay Area, CA
Posts: 1,697
Re: Lockup Converters
rkrause - what about dyno tuning? They lock it up in 4th and go WOT. I had it tuned about a month ago and now i'm having problmes with lockup in 4th!
see this thread..... http://web.camaross.com/forums/showt...16#post3779916
the problem is getting progressively worse
see this thread..... http://web.camaross.com/forums/showt...16#post3779916
the problem is getting progressively worse
07-07-2006, 11:07 AM
#33
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Re: Lockup Converters
i assumed it was fourth cuz the revs sounded like it, and the car went up to 161 mph on the dyno. I don't think 3rd can do that.
I found out its not a converter problem, the tranny is slipping in 4th now.
I found out its not a converter problem, the tranny is slipping in 4th now.
07-12-2006, 02:33 AM
#34
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Join Date: Jul 2000
Location: MD
Posts: 520
Re: Lockup Converters
One thing that a few of you seem to be confusing is that stall speed and STR (Stall Torque Ratio, torque multiplication) have no relationship. You can build a higher stall converter with a higher or lower STR depending on vane and mostly stator designs. Typically there are reasons why you don’t just build every converter with the highest torque multiplication ratio possible, on the street the issue is that usually higher ratios result in a converter that is less efficient, slips more above the stall speed and makes more heat, and in a race car the ratio can be used to tune for the power band of the engine, chassis setup, tires…
Besides what was already noted with a lot of cars running faster with the converter locked (again, you could jumper the terminals on the ALDL connector or just run 2 wires to the backs of the terminals and mount a switch… FWIW, more then a couple of miles of normal driving with it locked like this will set an SES), some of this statement just doesn’t make sense, primarily the argument that it would slow the car down.
When making a pass, in most cases the only place that you’ll the converter below stall is off the line, once you leave the line you’re pretty much above the stall speed the rest of the pass (one exception that I can come up with is some TPI cars with moderate stalls in them will drop below the stall speed on shifts). That being the case the 5-10% slip that you’re getting at the converter is nothing more than that, slip, loss of power. Locking the converter would be nothing except a gain.
This is also pretty much the case in cruising around with a stockish setup, stock stalls are usually in the 1200-1800rpm range and you’ll rarely shift below that point.
No argument on the durability side here and that is probably the only reason why it is done the way it is from the factory… first, most stock clutches are not designed for the kind of loads that we can put on them “beating” on our cars (or towing with a truck…), and second, that slippage on the shifts can really make a big difference in the tranny’s lifespan, a little bit of slip in a fluid coupling is much preferred to programming a little slip in a clutch pack or band. This is really noticeable when you install a higher stall converter and install a shift kit. You can program for MUCH firmer shifts with a higher stall converter then you could without it without the shifts being all that harsh, just because of the extra slip of the higher stall converter.
It’s also important to not that this is a GM thing. For example, the ford AOD tranny uses a 2 piece input shaft and the converter only stalls in first gear, in the rest of the gears the second piece of the shaft is used that provides a direct drive, there is no TCC at all, so basically, if you’re not in 1st you’re locked up.
Originally it was strictly a durability and a weight issue. Durability in that even the stock clutches were marginal when pushed in stock applications, and that most performance converters didn’t have the room for them, and that stock GM did some weird things in the name of MPG with fluid routing when the converter clutch is locked. Weight, well that’s an obvious, the volume of the converter goes up dramatically as it’s size is increased and with that the weight of the converter and fluid result in a slower revving/less responsive engine. An extreme example is the stock converter used in something like an 4L80e… since it was designed for trucks I’m sure that that wasn’t really a concern for gm and from their perspective extra rotating weight will make things smoother and pull down at lower rpm’s better, but that converter is in the range of 70#...
FWIW, as people found out that there was performance to be had by locking the converter on a pass some markets (notably the Sy/Ty guys) started seeing UFO converters, where they grafted the big front end/cutch assembly to a smaller converter on the back to get the advantages of a small, high stall converter and also that of a large TCC clutch.
I have a 3 disk lockup Vigilante converter in my 4L80e, basically their upgrade/custom setup. They claim it to be RELIABLE when locked up under power at up to 1600hp (bothers me slightly that they give you an HP number rather then a torque number). As of yet I haven’t played with it to find out, but I do think it would be wild if you could haze the tires on a TCC lockup.
Originally Posted by rskrause
Well, first of all, performance would suffer. With lockup, the converter ceases to multiply torque. It also effectively makes the converters stall speed 0 rpm. This obviously puts you way out of the powerband at low speed. The cushioning effect of the converter on the tranny is also lost, which would decrease tranny life when shifting during hard acceleration. Overall, it would slow the car down.
When making a pass, in most cases the only place that you’ll the converter below stall is off the line, once you leave the line you’re pretty much above the stall speed the rest of the pass (one exception that I can come up with is some TPI cars with moderate stalls in them will drop below the stall speed on shifts). That being the case the 5-10% slip that you’re getting at the converter is nothing more than that, slip, loss of power. Locking the converter would be nothing except a gain.
This is also pretty much the case in cruising around with a stockish setup, stock stalls are usually in the 1200-1800rpm range and you’ll rarely shift below that point.
No argument on the durability side here and that is probably the only reason why it is done the way it is from the factory… first, most stock clutches are not designed for the kind of loads that we can put on them “beating” on our cars (or towing with a truck…), and second, that slippage on the shifts can really make a big difference in the tranny’s lifespan, a little bit of slip in a fluid coupling is much preferred to programming a little slip in a clutch pack or band. This is really noticeable when you install a higher stall converter and install a shift kit. You can program for MUCH firmer shifts with a higher stall converter then you could without it without the shifts being all that harsh, just because of the extra slip of the higher stall converter.
It’s also important to not that this is a GM thing. For example, the ford AOD tranny uses a 2 piece input shaft and the converter only stalls in first gear, in the rest of the gears the second piece of the shaft is used that provides a direct drive, there is no TCC at all, so basically, if you’re not in 1st you’re locked up.
Why don't race converters have lockup mechanisms? First, it would be difficult to design and produce a clutch mechanism to fit into the available space that would handle the amount of power the would need to be transmitted. In that regard, keep in mind that high stall race converters are quite a bit smaller than street converters. Typically 8" or 9" diameter versus up to 12" for street converters. The extra rotating mass would also be a negative. But more to the point, at least for a drag car, it would probably slow the car down to lockup the converter. Maybe you could get a couple of more mph at the big end locking up just at the end of the track. But the gain would not be large.
FWIW, as people found out that there was performance to be had by locking the converter on a pass some markets (notably the Sy/Ty guys) started seeing UFO converters, where they grafted the big front end/cutch assembly to a smaller converter on the back to get the advantages of a small, high stall converter and also that of a large TCC clutch.
What you want to avoid is lockup under WOT as the stock converter was certainly not designed to do this, even behind a stock motor. Vigilante claims to have designed their converters to lockup reliably behind fairly stout motors. They make a hp claim that I can't recall at the moment. I can't verify this one way or the other.
Last edited by WS6 TA; 07-12-2006 at 02:36 AM.
11-05-2006, 04:52 AM
#35
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Actually,this happened to me with an inexperienced dyno operator at a shop in Memphis. I do not have a dyno graph of that run since the operator realized that at 140+ MPH.... there was something wrong lol, {where the dyno machine saftey circuit shut the system down and no results of that run were saved, {or at least not for me to see.}.
------------------------
Originally Posted by rskrause
Well, it doesn't appear to me that the TCC locks up under WOT based on what I have seen on the dyno. After all, isn't why A4's consistently dyno 15-20hp less than an M6? IF the TCC locked up, I think they should dyno ~ the same. But I sure could be worng on this one.
rskrause
rskrause
I'd say the automatic RWHP 'with locked converter' would be close to the manual tranny's RWHP * other than the fact that the auto requires some extra power at all times for supporting the hydraulic pumps resistance, {which provides pressure to apply whichever circuit{s} are in use at the time.
And also, the automatic's hard parts, used to transfer the power, {looking at rotating assembly weight issues}, scale in at a consinderable bit more weight than the manual tranny parts do. ...
One more thing..., the automatics basic component weight, being more than the manual, will eat a few ponies there.
All things considered, I'd think if the 4l60e and converter are built with the components to hold the power, enough power is being supplied by the motor, and the PCM flash is correct, the difference in dyno numbers should be fairly similar. JMO
Originally Posted by Fast Caddie
there is definitely a benefit of locking the TCC after the torque multiplication has been utilized after the launch. The launch is when the TC's torque mulitplying ability takes place while it's in "overrun" state... meaning the shearing of the fluid acts like a large rubber band and thrusts the car forward while the two sides of the TC try to catch up to each other in regards to rpm. But after it does catch up, torque multiplication ceases and then the slippage eats up your power the rest of the way down the track... locking the TC after the overrun state is done combats this, but is pure hell on the TC clutch pack.
The main intention of a higher stall converter is to get the motor into an RPM range where it is making more power {when launched}. A motor built to run at a maximum power output in RPM ranges above that of general factory built units will suffer performance at the lower RPM's, and when linked to a converter with a stall speed RPM designed for {factory} street based motors, will not perform to potential...
Likewise; When a street based motor linked to a converter with stall speeds that are above it's RMP output range, the stall speed becomes a power eater, and the STR is only applicable for a short spred of the powerband-to-speed ratio, which becomes irrelivent at higher speeds.
{BUT} As discussed, lock-up circuits can eliminate, {or for the most part at least}, the lost power in the situation of higher speed when the stall speed and STR are way less applicable toward transmitting power to the ground.
Also, running a higher stall speed converter will certainly require modifying the tranny hydraulic circuit to match as well as the PCM program in a post 'non-electronically controlled' unit. There are several ways to trick-out the tranny, but if the motor won't support the characteristics of the converter then transmission modifications will have minimal effects.
I'd like to comment on a couple of more responses in this thread but I don't have time, or want to waer out my welcome.
Excellent thread IMO to all that have posted here.
11-05-2006, 05:08 AM
#36
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I have gone back and looked at some PCM .bin files for A4's and yes, they will lock up under WOT. What's interesting is that you don't "see" this in the dyno generated power curve. This supports the concept that a properly designed converter doesn't "slip" much once it's past the stall speed.
Rich
Rich
11-05-2006, 05:12 AM
#37
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Location: Calimesa, California. US
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"For example, the ford AOD tranny uses a 2 piece input shaft and the converter only stalls in first gear, in the rest of the gears the second piece of the shaft is used that provides a direct drive, there is no TCC at all, so basically, if you’re not in 1st you’re locked up."
The AOD does not lock the torque converter till you go to 3rd gear, not 2nd as you stated. Non lockup TC's work great with this unit.
The AOD does not lock the torque converter till you go to 3rd gear, not 2nd as you stated. Non lockup TC's work great with this unit.
11-05-2006, 09:54 AM
#38
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Join Date: Feb 2006
Posts: 46
Grunt off the line
I have been reading the Torque threads and I appreciate it. But having trouble trying to understand what I should do best to get more grunt off the line in street or casual strip use.
I have a 2002 SS with 3.23 gears. Do I go the 3.73 gear route or get a 3k-3.5k torque converter change. If I do one do I have to do the other?
Thanks
I have a 2002 SS with 3.23 gears. Do I go the 3.73 gear route or get a 3k-3.5k torque converter change. If I do one do I have to do the other?
Thanks
11-10-2006, 02:40 PM
#39
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Join Date: May 2003
Location: Ocala FL
Posts: 268
I have been reading the Torque threads and I appreciate it. But having trouble trying to understand what I should do best to get more grunt off the line in street or casual strip use.
I have a 2002 SS with 3.23 gears. Do I go the 3.73 gear route or get a 3k-3.5k torque converter change. If I do one do I have to do the other?
Thanks
I have a 2002 SS with 3.23 gears. Do I go the 3.73 gear route or get a 3k-3.5k torque converter change. If I do one do I have to do the other?
Thanks
As far as needing to install a lower ratio, {higher numerically} gearset and higher stall converter together, yes it would be beneficial to the higher stall speed at the first stage of acceleration, but it would also be benificial to the first stage of acceleration {stall or no-stall}, but after a certian ground speed point, the extent of your LS1 motor's ability to make power at high RPM would become a big factor, and with the HP/TQ curve of a basic heads, cam, exhaust, tuning ect. motor, the stall / gear ratio combo may not be very efficient beyond a certain point: maybe even a liability - which I've seen with several cars, some of my own included that were stalled with a converter that really killed the RPM vs ground speed RWHP/RWTQ because of a motor that was not built to match, or vise-versa.
A situation where a higher stall converter is always certainly needed is in combo with a cam profile that is intended for maximum horsepower output at high RPM. Some cam profiles are intended to increase low RPM torque like in 4WD off road applications and in this case a higher stall may not be the set-up needed.
Okay, I've worn out my welcome here for now.
With a stock or near stock motor I would reccomend the gearset over the converter anyday.
I got way more increase in performance, trap speed, and ET when I put Strange 3.73's in mine than when I install the 3k stall.
JMO - Have fun!!!
02-22-2007, 11:18 PM
#40
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Join Date: Feb 2007
Posts: 2
Hey Guys
Quick question.
Im putting a 700r4 in my wifes 80 camaro Z28. Im going to run a 2400-2800 stall with 4.10 gears. It has a 375 hp 350. This car will be 99.99% street driven (but driven hard) Question is if I can control the heat and dont care about gas mileage can I run a non lock converter and is it possable to control the heat? It will have the biggest cooler in front of the radiator that I can get.
Thanks for the help!!!
Quick question.
Im putting a 700r4 in my wifes 80 camaro Z28. Im going to run a 2400-2800 stall with 4.10 gears. It has a 375 hp 350. This car will be 99.99% street driven (but driven hard) Question is if I can control the heat and dont care about gas mileage can I run a non lock converter and is it possable to control the heat? It will have the biggest cooler in front of the radiator that I can get.
Thanks for the help!!!
02-22-2007, 11:23 PM
#41
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If you have a good cooler, and aren't running in stop and go traffic for long periods, a 2,400-2,800 stall should be no problem whatsoever. Why not use a lockup converter if you can?
Rich
Rich
02-23-2007, 09:03 AM
#42
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Join Date: Feb 2007
Posts: 2
Just the added expense of the converter and the switch and getting it all working together. I just saw a few posts up that pro built automatics is on here, I am buying his upgrade rebuild kit. What does a vacuum switch for the lockup cost? Can I just run a wire for the existing brake light switch to the tranny to control lockup instead of buying some 40 kit?
Thanks
09-08-2007, 01:49 PM
#43
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Join Date: Jul 2006
Posts: 420
Well i have a tci superstreet fighter stall and it locks up at 95wot in 3rd,and traps 129 @ 10.60s with the stall unlocked it traps 125@ 10.70-10.80s, but now the conveter isnt lock up like it did its hitting real soft any ideas what i should do or who can fix the stall? Also the car has 3.73 and 26inch tires and if the conveter is un locked it hits the rev @7000 just before the 1/4.
09-16-2007, 12:15 PM
#45
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Posts: 420
think about going with this anyone else use it can it handle being locked up in 3rd wot?
converter#MR-1. " MegaRaptor-1 " Performance gains of 2/10 of a second in 60 feet and up to 3/4 of a second in the quarter mile have been reported. The torque multiplication rates can be ordered in 2 to 1, 2.5 to 1 or 3 to 1. The torque multiplication of this converter will deliver an increase of up to 50 horse power to the rear wheels. The MegaRaptor-1 with its carbon fiber clutch will withstand power levels of 700 horse power. This 9 1/2 inch converter can be ordered with stall speeds of 2000 to 5500 RPM. The Ultimate Top of the Line Single Clutch Lock-Up Converter. Two year warranty on workmanship and materials and one free restall. Fits 700R4, 200-4R and early style 4L60E transmissions. Cost $675.00
converter#MR-1. " MegaRaptor-1 " Performance gains of 2/10 of a second in 60 feet and up to 3/4 of a second in the quarter mile have been reported. The torque multiplication rates can be ordered in 2 to 1, 2.5 to 1 or 3 to 1. The torque multiplication of this converter will deliver an increase of up to 50 horse power to the rear wheels. The MegaRaptor-1 with its carbon fiber clutch will withstand power levels of 700 horse power. This 9 1/2 inch converter can be ordered with stall speeds of 2000 to 5500 RPM. The Ultimate Top of the Line Single Clutch Lock-Up Converter. Two year warranty on workmanship and materials and one free restall. Fits 700R4, 200-4R and early style 4L60E transmissions. Cost $675.00