Launch with auto GM6 problems... Please Help!
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Launch with auto GM6 problems... Please Help!
I asked before (I think it was on rs25.com's forums) how to launch my car the best way with minimal damage. I got this response (forgot who posted it... i think it was RS25, the mod/admin). My car is a 1998 Impreza 2.5rs with an automatic transmission.
I tried it once (in the snow, so probably not as bad on the car as in the dry), i left it in 1st when i revved up and launched it, and shifted to second at redline. That was about a month ago, and now my car is in the shop getting a new tranny (under warranty, thank god), because my car makes a huge bang from the 1-2 shift and bogs down from the 2-1 shift. I don't know if it was caused from the launch though...
My question is... is what is quoted above a good and safe way to launch fast? I would imagine it would not only have a huge stress on the tranny fluid... but also the brakes for holding the car still at several thousand RPM in 1st gear... Im not sure if it disconnects when in 1st and not moving and connects when you release the brake though... maybe it does... i have no idea
thanks for your help =)
You don't need to pump the brakes, just push them down. Then floor it and build the RPM until it won't rev any more, then take your foot off the brake.
However, do note, revving the engine in gear will heat up the tranny fluid VERY quickly (like 2-4 seconds) and HEAT is what kills automatic transmissions. So, wait until the last few moments to launch. If you hold it like that for 10+ seconds you are asking for trouble. Depending on how often you launch, have the dealer flush and refill your tranny. They have a special tool which completely drains and refills it, where if you do it you can only drain the pan.
However, do note, revving the engine in gear will heat up the tranny fluid VERY quickly (like 2-4 seconds) and HEAT is what kills automatic transmissions. So, wait until the last few moments to launch. If you hold it like that for 10+ seconds you are asking for trouble. Depending on how often you launch, have the dealer flush and refill your tranny. They have a special tool which completely drains and refills it, where if you do it you can only drain the pan.
My question is... is what is quoted above a good and safe way to launch fast? I would imagine it would not only have a huge stress on the tranny fluid... but also the brakes for holding the car still at several thousand RPM in 1st gear... Im not sure if it disconnects when in 1st and not moving and connects when you release the brake though... maybe it does... i have no idea
thanks for your help =)
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Car Info: 02 Impreza WRX sedan
Originally posted by awddrifter
That was about a month ago, and now my car is in the shop getting a new tranny (under warranty, thank god)
<snip...>
My question is... is what is quoted above a good and safe way to launch fast? I would imagine it would not only have a huge stress on the tranny fluid... but also the brakes for holding the car still at several thousand RPM in 1st gear
There is no safe way to launch an OEM automatic. Eventually, brake torquing a stock transmission will cause component failure, as you've already found out. Depends how often you do it and how much power the engine is putting out. There may be some benefit to aftermarket transmission fluid and a transmission cooler.
Brake torquing won't hurt brakes. Brakes are under the most stress when dissipating heat from application at high speeds. Not the case when the car isn't moving. Mashing the stop pedal down only creates high pressure in the brake lines but the lines and seals can take it. In this case, the heat generated from all that engine power is within the transmission and torque converter when the car isn't moving. Think of brake torquing as a way to try to bring transmission fluid to its flash point in the shortest amount of time. Just kidding, but I think you get the point.
Unfortunately, if you want to go quick with a stock automatic transmission, brake torquing is what you have to do to cut low E.T.s.
Im not sure if it disconnects when in 1st and not moving and connects when you release the brake though
I don't understand the question...
--
0==WW==0
"…axles of evil…" - george w. bush
That was about a month ago, and now my car is in the shop getting a new tranny (under warranty, thank god)
<snip...>
My question is... is what is quoted above a good and safe way to launch fast? I would imagine it would not only have a huge stress on the tranny fluid... but also the brakes for holding the car still at several thousand RPM in 1st gear
There is no safe way to launch an OEM automatic. Eventually, brake torquing a stock transmission will cause component failure, as you've already found out. Depends how often you do it and how much power the engine is putting out. There may be some benefit to aftermarket transmission fluid and a transmission cooler.
Brake torquing won't hurt brakes. Brakes are under the most stress when dissipating heat from application at high speeds. Not the case when the car isn't moving. Mashing the stop pedal down only creates high pressure in the brake lines but the lines and seals can take it. In this case, the heat generated from all that engine power is within the transmission and torque converter when the car isn't moving. Think of brake torquing as a way to try to bring transmission fluid to its flash point in the shortest amount of time. Just kidding, but I think you get the point.
Unfortunately, if you want to go quick with a stock automatic transmission, brake torquing is what you have to do to cut low E.T.s.
Im not sure if it disconnects when in 1st and not moving and connects when you release the brake though
I don't understand the question...
--
0==WW==0
"…axles of evil…" - george w. bush
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You likely cooked the transmission launching it that way. Get a transmission cooler and a trans temp gauge installed so that you at least have an idea how hot things are getting. If you want to race a A/T then looking into getting a higher torque converter installed as well as a new valve body for harder shifts. It will let you get off the line at a higher RPM and not have nearly as much lag when it shifts gears.
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Got my car back today... and it turns out it DIDN'T have any problems (unlike they told me) and they decided to just change the tranny fluid (just empited the pan.. didn't flush out the whole tranny)
But when i was driving home, it still gave me a HUGE jolt from the 1-2 shift, so I dunno what the mechanic is on, but it must be something that makes you #&@*ing stupid.
Im bringing it back tommorow probably to drive with the guy in it and show him whats wrong... im only giving it half acceleration too, not flooring it, when it does this.
One last thing, should I leave the gear selector in 1st and rev up to launch? or leave it in drive? Im not planning to race my auto or anything, or probably even launch it that much at all, I just wanna know for some knowledge about my car =)
But when i was driving home, it still gave me a HUGE jolt from the 1-2 shift, so I dunno what the mechanic is on, but it must be something that makes you #&@*ing stupid.
Im bringing it back tommorow probably to drive with the guy in it and show him whats wrong... im only giving it half acceleration too, not flooring it, when it does this.
One last thing, should I leave the gear selector in 1st and rev up to launch? or leave it in drive? Im not planning to race my auto or anything, or probably even launch it that much at all, I just wanna know for some knowledge about my car =)
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