A few Q's about Stalls, Trans-Brakes, and Shift-Kits (4L60e)
06-16-2009, 10:35 AM
#1
Teching In
Thread Starter
Join Date: Apr 2007
Posts: 11
Likes: 0
Received 0 Likes
on
0 Posts
A few Q's about Stalls, Trans-Brakes, and Shift-Kits (4L60e) Hi all,
I've never really thought about doing any mods to my transmission but after reading the sticky posted on here I figure it's about time... My car is a 2000 SS with a lid, magnaflow exhaust and cat-back.. I'm fairly happy with it performance wise for now and I really would like to reinforce my tranny now so I don't have to pick up pieces of it later..
I did a search and tried my best to find answers to these but nothing specific really came up... so my Questions:
Stall:
How large a stall would I need for my car? I was thinking somewhere between 3400-3600, I still would like to keep it primarily as a DD while occasionally hitting the track (maybe once or twice a month) and what about the STR rating? Also, can someone explain to me why there's a decrease in city MPG when one of these are installed? Does it keep higher revs when driving around town? Since I have a modified exhaust I would prefer to keep low revs as it gets kinda loud after 3000 rpms and I don't need any extra attention from the boys in blue.
Trans-Brake:
Would this be an alternative to a stall? is it possible to have both installed? what are the pros/cons? I understand they hold 1st and reverse gears together when engaged to maintain higher revs during launches. So I can't see how having both would work? Is there a better one or are they more a personal preference thing?
Shift-Kits:
I have no clue what their purpose is or how they work (do you have to shift manually?), the only thing I have read is that they can help prolong the life of a transmission significantly
Well those are my questions, any input would be greatly appreciated
Thnx
I've never really thought about doing any mods to my transmission but after reading the sticky posted on here I figure it's about time... My car is a 2000 SS with a lid, magnaflow exhaust and cat-back.. I'm fairly happy with it performance wise for now and I really would like to reinforce my tranny now so I don't have to pick up pieces of it later..
I did a search and tried my best to find answers to these but nothing specific really came up... so my Questions:
Stall:
How large a stall would I need for my car? I was thinking somewhere between 3400-3600, I still would like to keep it primarily as a DD while occasionally hitting the track (maybe once or twice a month) and what about the STR rating? Also, can someone explain to me why there's a decrease in city MPG when one of these are installed? Does it keep higher revs when driving around town? Since I have a modified exhaust I would prefer to keep low revs as it gets kinda loud after 3000 rpms and I don't need any extra attention from the boys in blue.
Trans-Brake:
Would this be an alternative to a stall? is it possible to have both installed? what are the pros/cons? I understand they hold 1st and reverse gears together when engaged to maintain higher revs during launches. So I can't see how having both would work? Is there a better one or are they more a personal preference thing?
Shift-Kits:
I have no clue what their purpose is or how they work (do you have to shift manually?), the only thing I have read is that they can help prolong the life of a transmission significantly
Well those are my questions, any input would be greatly appreciated
Thnx
06-16-2009, 12:30 PM
#2
12 Second Club
You need to fully understand what each mod does before do any any of them.
A tq converter is the coupling between the flex plate (engine) and transmission. It is basically a hydraulic pump that as the engine spins it spins the transmission. It has a series of fan blades like a jet engine that as RPMs increase causes the turbine to spin and in turn spins the transmission. The whole point is to allow the engine to idle at a stop without stalling the motor, just like pushing in the clutch pedal on a M6 car. When the converter is spinning slowly the fluid flows right over the turbine and free spins. AS RPMs increase the fluid stalls out and forces the turbine to spin. The stall rating is an estimate of when this will happen. A higher stall rating allows an engine to stay up in its power band and take more advantage of a phenomenon called tq multiplication. When the engine spins faster than the transmission tq is multiplied by the effective reduction in gearing. The amount of tq multiplication is rated as STR. You will lose city mpg because the converter is slipping more at part throttle (below the stall) and therefore the engine rpms will be higher. This slipping will also create heat and shorten transmission life unless properly cooled. A good converter is a lot of fun but will not "reinforce [your] tranny now so [you] don't have to pick up pieces of it later".
A trans-brake is a mechanism specifically for drag racing that engages forward and reverse at the starting line. This does several things for a drag racer. It holds the car in position so he does not need the brakes. It disengages very quickly improving reaction times and hits very hard reducing 60' et. It also allows the driver to increase RPMs above the brake stall on the converter. This is the RPM at which your car would start to spin the tires with the brakes applied. The effect is less lag in the motor which again reduces rt and 60' et. If you are not a serious drag racer, skip it.
Shift Kits change the amount of pressure in the passageways of a transmission. They can make the transmission shift harder and hold rpm longer. If you've ever ridden in a hot rod that has a real violent 1-2 shift on the street, you've felt a shift kit. At part throttle they can feel like a kick in the pants or make a thud, in some cases breaking the tires free for a split second. They smooth out at WOT because the increased tq causes the transmission to slip just a bit taking the violence out of it. Some people say they increase trans life due to increased pressure on the clutches and reduced slippage. I don't know for sure. I believe they help more on a car with a higher than stock stall rating.
If you just want to prolong the trans, install a cooler and change the fluid/filter regularly. After you install the cooler: If you want to wake it up and still drive it on the street, go for a high quality mild converter (3200-3400 rpm) and possibly a shift kit. Stay away from the trans-brake until you get more into drag racing and mod the car more.
A tq converter is the coupling between the flex plate (engine) and transmission. It is basically a hydraulic pump that as the engine spins it spins the transmission. It has a series of fan blades like a jet engine that as RPMs increase causes the turbine to spin and in turn spins the transmission. The whole point is to allow the engine to idle at a stop without stalling the motor, just like pushing in the clutch pedal on a M6 car. When the converter is spinning slowly the fluid flows right over the turbine and free spins. AS RPMs increase the fluid stalls out and forces the turbine to spin. The stall rating is an estimate of when this will happen. A higher stall rating allows an engine to stay up in its power band and take more advantage of a phenomenon called tq multiplication. When the engine spins faster than the transmission tq is multiplied by the effective reduction in gearing. The amount of tq multiplication is rated as STR. You will lose city mpg because the converter is slipping more at part throttle (below the stall) and therefore the engine rpms will be higher. This slipping will also create heat and shorten transmission life unless properly cooled. A good converter is a lot of fun but will not "reinforce [your] tranny now so [you] don't have to pick up pieces of it later".
A trans-brake is a mechanism specifically for drag racing that engages forward and reverse at the starting line. This does several things for a drag racer. It holds the car in position so he does not need the brakes. It disengages very quickly improving reaction times and hits very hard reducing 60' et. It also allows the driver to increase RPMs above the brake stall on the converter. This is the RPM at which your car would start to spin the tires with the brakes applied. The effect is less lag in the motor which again reduces rt and 60' et. If you are not a serious drag racer, skip it.
Shift Kits change the amount of pressure in the passageways of a transmission. They can make the transmission shift harder and hold rpm longer. If you've ever ridden in a hot rod that has a real violent 1-2 shift on the street, you've felt a shift kit. At part throttle they can feel like a kick in the pants or make a thud, in some cases breaking the tires free for a split second. They smooth out at WOT because the increased tq causes the transmission to slip just a bit taking the violence out of it. Some people say they increase trans life due to increased pressure on the clutches and reduced slippage. I don't know for sure. I believe they help more on a car with a higher than stock stall rating.
If you just want to prolong the trans, install a cooler and change the fluid/filter regularly. After you install the cooler: If you want to wake it up and still drive it on the street, go for a high quality mild converter (3200-3400 rpm) and possibly a shift kit. Stay away from the trans-brake until you get more into drag racing and mod the car more.
06-16-2009, 12:49 PM
#3
Teching In
Thread Starter
Join Date: Apr 2007
Posts: 11
Likes: 0
Received 0 Likes
on
0 Posts
wow good info and i def learned something new.. thx a lot 91RS383!
Just out of curiosity, how violent can the 1-2 shift get? could it possibly cause any problems for my rear end?
Just out of curiosity, how violent can the 1-2 shift get? could it possibly cause any problems for my rear end?
06-16-2009, 01:18 PM
#5
12 Second Club
How violent do you want it? They range from barely there, to almost unstreatable. Be smart about it and you'll be fine. A strip only, or racing, shift kit is just that. The shift kit I had in my '91 was middle of the road and would ocasionally bark the tires on the 1-2 shift. In the rain, watch out! When I went around a corner I had to let it idle or make sure it didn't go over 15 mph or it would shift, break the tires loose and fishtail. Twice it completely spun the car.
