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Old 09-08-2002, 05:13 PM
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Post Tranny being really wierd....

Ive got a 95 Camaro Z/28. Its the automatic tranny, I belive it is a 4L80. Just recently, when I go to down shift to slow down, the tranny slips. For example, Ill be doing 60 and I shift it into 3rd or 2nd to slow down, the car will jerk like it down shifted, but the rpms stay down and it feels like the car is in neutral coasting. A few times it has made a wwooooooppp sound when I down shifted. I cant really explain the sound but thats as close as I can describe. BUT, when your on the gas, the tranny works fine. No slipping or anything. Can someone please tell me its nothing too serious, cuz I hate working on these new cars. Any info will help, thanks <img src="graemlins/drool.gif" border="0" alt="[drool]" />

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Old 09-10-2002, 11:44 AM
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i would think that you might have broken a sprag, in your 4L60, (thats what it is, the 4l80 comes in trucke and is like a 400 with overdrive,) what might have you confused is the bolt off bell housing, buts its an 4l60 all the same.
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Old 09-11-2002, 06:17 AM
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whats a sprag?
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Old 09-12-2002, 06:36 PM
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??????
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Old 09-12-2002, 06:47 PM
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How fast are you going when you shift from overdrive into 3rd SOMETIMES 2ND? What? 60mph into 2nd??? There's your problem. Poor poor tranny...
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Old 09-12-2002, 11:07 PM
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A sprag is a one way clutch that prevents motion in one direction, as in when you downshift from such a high speed the clutch suddenly has to accelerate to Mach 1 while your using the trans to do a brakes job. You may have ruined the sprag clutch but at this point I would just stop abusing your transmission like this and see if any other damage is apparent. Use your brakes to decelerate the vehicle and downshift to accelerate once you have slowed down. You will eventually destroy your trans if you continue to drive the car in this fashion, you might want to read this guys book or take his course.
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Old 09-13-2002, 05:28 PM
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Um, I think you guy took my info in wrong, or I didn't explain it clearly, When im doing 60mph, im only reving like not even 2,200 rpms, when I go down a hill, the car likes to speed up and when im behind someone, I just downshift to 3rd, which only brings my rpms to about 2,800, and it slows the car down a little so I don't have to constantly drag the breaks. I sometimes down shift to second when im really slowing down fast to help the breaks out a little, I don't go like 90 then downshift to second, im not that stupid. But, will the tranny last just driving it without downshifting at all? How serious is this problem?
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Old 09-13-2002, 08:13 PM
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Don't use the trans to slow the vehicle down, that's what everyone is saying. Automatic transmissions are not designed to handle this kind of treatment on a regular basis, some heavy duty truck trannies maybe but not passenger cars. The manufacturer would call this abuse and refuse warranty if you tried to claim it. There is no other way to say it, stop doing it or it's going to cost you.
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Old 09-14-2002, 08:06 AM
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I dont understand, why do the cars come with a shifter to where you can down shift into 3rd, 2nd, or 1st if the tranny can't handle it? What happens when your pulling a load?? Sometimes your brakes can't handle the weight and you downshift to slow down. Every one I know down shifts their cars a gear when they are going down a hill when they don't want to drag the brakes, even in drivers ED, they showed a video that tells you to down shift when your going down a steep hill. On top of that, Ive owned many many cars with automatic transmissions that I had always down shifted all the time. Before I smartened up, I was beating the piss out of every car I drove, everything from ford mavericks, to broncos, vw's, cutlasses, el caminos, ford trucks, chevy trucks, camaros, firebirds, nissans, toyotas. In my El camino, I had a slap shifter and I would drive it like a standard all the time, I would down shift the thing into 1st doing 50 mph to slow down and enjoy hearing the tires squeal and the car kicking out sideways. One time I lost my brakes in RI, and I had to get back to CT, and guess how I made it.... I down shifted it and threw the damn thing in reverse everytime I had to stop!! And I made it. It helped a little having a 2400 stall converter for a little cushin. Same with my 81 camaro, I down shifted that thing all the time to slow down, even my 78 bronco, man, shifting into first with that thing with the 35in tires would scare the **** out of people a mile away, hearing that deep tire yelp sound. But I never had any problems with any of the trannys. I did this with everything and NEVER had any tranny problems at all. Now I get this 4th gen camaro w/ just under 100,000 miles on it, and since ive smartened up a little over the past couple of years, and since I payed 6 times more for it than any of my other cars, I havn't been beating on it that much at all, now I have this problem, I don't get it.
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Old 09-14-2002, 09:55 AM
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What can I say Chev? Roll on!
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Old 09-17-2002, 07:09 PM
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newer vehicles like for example a ford expedition, comes with a button on the shifter to downshift from fourth to third when ur goin down a hill, it even tells u in the owners manual to do this and yea in drivers ED they do tell you to do that nowadays but if the tranny cant take it then they shouldnt make it like that, and how bout brand new cars that are semi-automatic what about them you can shift if you want or dont simple as that...

my theory---drive it like a standard...lol
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Old 09-17-2002, 07:13 PM
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yea, drive it like a standard!! Sounds like..."drive it like you stole it"!!
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Old 09-17-2002, 08:20 PM
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The point you guys are missing is that with a standard transmission you have to match rpm to downshift (syncros only do so much), with an automatic you have to do the same thing...if you don't then the trans will over-run the sprag clutch and slip the bands. Not good.

What you are in effect doing is making the auto trans syncronize engine and drivetrain rpm in different gear ratios, this is accomplished with slippage. If it didn't the car would lock the tires on a downshift, any slippage is bad and driving this way won't kill it right away. BUUUUUT it is a bad habit to get into, brakes are for slowing the car and trannies are for ratio changes. Using the trans for slowing the car is described for use on descending hills and occurs at a light load, any road race track will provide enough clues that you should listen for when your there. They don't downshift until the corner apex or just before, using the trans to slow the car under race conditions needlessly heats the oil and will kill a trans faster than you can say "burnt bands"...never mind the clutch.

When an automatic downshifts it grabs the next lower gear with less force than a full throttle upshift would...this means slippage and heat. You don't downshift before the corner, you downshift in it when the speeds are low and the load is light. These are good rules to follow with any kind of transmission, if everybody did it I bet the trans rebuild shops would go out of business.

At the very least I would change the trans oil, it's probably had it. <img src="graemlins/nono.gif" border="0" alt="[nono]" /> :p
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Old 09-17-2002, 08:40 PM
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4 Jaw is exactly right. Transmissions are for changing gear ratios. Modern transmissions are very complex, and in most instances (particularly in today's vehicles) not very sturdy. I own a small repair shop, and alot of transmissions croak under fairly normal conditions, let alone doing manual downshifts all of the time.
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Old 09-17-2002, 08:41 PM
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Thanx for all the info Jaw 4 Chuck, I understand now why it might be doing this, but I really havn't been manually downshifting or beating on this car that much at all, maybe the owner before me beat the crap out of it and im getting the results. I havn't really been driving it that much anyway, ive got my 69 camaro out for the summer, and a couple of other beaters. I guess im just kind of upset that I could be so hard on older cars for a long time and never have any problem, and I get a newer car which I actually spend more than $800 for, more like over $7000 and I get these stupid problems, I had a fuel problem too, I ended up spending 80 bucks for a scan test to have the shop tell me I needed a number 1 fuel injector which they said was going to cost $500+ to fix. I ended up putting fuel injector cleaner in a low tank and it started running fine!! It was just a stuck injector!! Im just going to sell the car and let someone else deal with it, Ill stick with the older cars....much cheaper and easyer to work on.

[ September 17, 2002: Message edited by: chevyelc81 ]</p>
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