Exceeding Redline In 1998 Trans Am With Automatic Transmission?
08-02-2012, 01:21 PM
#1
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Exceeding Redline In 1998 Trans Am With Automatic Transmission? I have a 1998 Trans Am with an automatic transmission. I've been wanting to see what my 0-60 and 1/4 mi. times are, but I was told by the dealership that the 1998s are not equipped with a rev limiter. I realize I can blow the transmission by downshifting at high speed, but in a 1/4 mile or 0-60 time test, there's no reason I'd ever need to downshift -- only upshift. So my question is this: If I leave my automatic in high gear at the start line, and then stomp on it when the flag goes down, will my transmission ALWAYS upshift to the next gear before I reach redline, no matter how hard I drive it? I've looked all over your forum for the answer, but I can't find it. My fear of overreving my engine with no built-in protection, and the huge cost involved if I do, is what's keeping me off the track. I'd appreciate it if only members with extensive background in racing and/or automatic transmissions answer this question. In other words, gearheads 
not boneheads. 
Thanks!
not boneheads. Thanks! 
08-02-2012, 02:04 PM
#2
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The guy at the dealership is a moron. Your car has a rev limiter, 6200 or 6300rpm if think. If 98's didn't have rev limiters then mine would be dead after missing 3rd gear at the drag strip a few months back. Also assuming your car doesn't have anything wrong with it's transmission it will upshift for you when you leave it in high gear, in fact that will more than likely net you your fastest time.
08-02-2012, 02:08 PM
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The 4L60E is controlled by the PCM, and it will prohibit manual downshifts above certain speeds for certain gears (if you manually put the shift level into 1st gear at 100mph, it will not allow this to acutally happen within the transmission).
Hopefully my experience/resume is good enough.
08-02-2012, 02:14 PM
#4
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Well, I've owned four of these cars (LS1/4L60E combos), and in those cars I've owned four stock 4L60E transmissions and two "built" 4L60E transmissions. One was tuned by a shop, and the other was tuned by me. I've raced with both the stock and built versions of these transmissions.
Hopefully my experience/resume is good enough.
Hopefully my experience/resume is good enough.
Just kidding of course!
08-03-2012, 08:34 AM
#6
My advice would be to never return to that dealership for information such as this ever again. They are completely wrong. Rev limit for your '98 is set to 6200rpm in the stock PCM.
The 4L60E is controlled by the PCM, and it will prohibit manual downshifts above certain speeds for certain gears (if you manually put the shift level into 1st gear at 100mph, it will not allow this to acutally happen within the transmission).
Yes, assuming that there is nothing wrong with your transmission causing it to slip or shift late, etc. And assuming that you have stock tuning or aftermarket tuning that has the proper relationship between shift points and the rev limiter (you don't want to set the rev limit and shift point to the same rpm, there needs to be a window between the two - the stock window was 200rpm [shift point at 6000, rev limit at 6200] but you can usually get away with as little as a 100rpm window if your trans is in excellent working order).
Unlike a manual trans car, you can't mechanically overrev a 4L60E car, so unless you remove the rev limiter via tuning, this should not be a concern.
Well, I've owned four of these cars (LS1/4L60E combos), and in those cars I've owned four stock 4L60E transmissions and two "built" 4L60E transmissions. One was tuned by a shop, and the other was tuned by me. I've raced with both the stock and built versions of these transmissions.
Hopefully my experience/resume is good enough.
The 4L60E is controlled by the PCM, and it will prohibit manual downshifts above certain speeds for certain gears (if you manually put the shift level into 1st gear at 100mph, it will not allow this to acutally happen within the transmission).
Yes, assuming that there is nothing wrong with your transmission causing it to slip or shift late, etc. And assuming that you have stock tuning or aftermarket tuning that has the proper relationship between shift points and the rev limiter (you don't want to set the rev limit and shift point to the same rpm, there needs to be a window between the two - the stock window was 200rpm [shift point at 6000, rev limit at 6200] but you can usually get away with as little as a 100rpm window if your trans is in excellent working order).
Unlike a manual trans car, you can't mechanically overrev a 4L60E car, so unless you remove the rev limiter via tuning, this should not be a concern.
Well, I've owned four of these cars (LS1/4L60E combos), and in those cars I've owned four stock 4L60E transmissions and two "built" 4L60E transmissions. One was tuned by a shop, and the other was tuned by me. I've raced with both the stock and built versions of these transmissions.
Hopefully my experience/resume is good enough.
08-06-2012, 04:49 PM
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my 98 TA really impressed me in terms of being idiot-proof. That's an excellent improvement in terms of technology, because I am one of those idiots sometimes
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08-07-2012, 11:40 AM
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When I asked for header bolts at the local dealer for my header swap the guy looked at me and said oh you're replacing the exhaust manifolds? Do you need those also? And I simply said yeah something like that and no I have it taken care of, do you have the bolts? Couple minutes later I had what I needed without trying to tell them anything more than they needed to know and not allowing them to give me "advice"
08-07-2012, 12:23 PM
#10
Don't ever manually shift your tranny. You'll burn your clutchs out downshifting and waste your time upshifting because the CPU controls the shift. Not you. You need alittle dragstrip time!
11-13-2012, 12:29 PM
#12
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Thanks guys. I really appreciate your answers and it does take a load off my mind. It amazes me though that the Service Advisors (more than one) that I questioned about this didn't know the 98s have rev limiters. After I got your answers, I did some internet research and came across tons of online parts stores that carry stock as well as upgraded rev limiters for 98 Trans Am's. Absolutely amazing! So it's time to hit the track now!
11-13-2012, 03:24 PM
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11-13-2012, 03:41 PM
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11-17-2012, 06:59 PM
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forum members will watch your back while you figure out what you have and what to do with it
09-14-2013, 02:35 PM
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I do have 1 more question. Redline is 6000 RPM. So if the purpose of the rev limiter is to protect the engine from over- revving, then why is it set at 6200 RPM? I would think Pontiac engineers should have set it at 5900 RPM. But since it is what it is I'm just wondering what Pontiac's rationale was for essentially setting a rev limiter to allow for over-revving the engine by +200 RPMs? Any former Pontiac engineers out there that can shed some light on this?
09-14-2013, 02:45 PM
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I do have 1 more question. Redline is 6000 RPM. So if the purpose of the rev limiter is to protect the engine from over- revving, then why is it set at 6200 RPM? I would think Pontiac engineers should have set it at 5900 RPM. But since it is what it is I'm just wondering what Pontiac's rationale was for essentially setting a rev limiter to allow for over-revving the engine by +200 RPMs? Any former Pontiac engineers out there that can shed some light on this?
6000rpm is just the "red line" as shown on the tach.
You're right, if the design limit was actually 6000rpm, then the rev limter would be set to this, and shift points would be set to ~5800rpm.
