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Discussion Starter #1
Since I've been driving my "new" STS, I noticed that the shift from 2 to 3 is harder than that of my SLS. I guess you could say it jumps into 3rd a little bit rougher than my SLS. Is that normal, or should I consider an ATF exchange at 83,000 miles to either Dex III or VI? I'm pretty certain the front center motor mount is OK since the idle is perfect and there is very minimal movement when shifting from R to D.
 

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2001 Seville SLS
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Changing the fluid is a good idea, but I doubt it will fix a harsh shift problem. The maintenance schedule calls for changing the fluid at 50 K under various conditions that are somewhat common.

City driving in over 90 degree weather.
Driving over hills or mountains.
Towing a trailer.
Limo or taxi service.
High performance operation.

A harsh shift only to 3rd gear rules out electrical problems relating to the pressure regulator valve. That means the problem will be inside the transaxle. If it were mine and the shift was bad enough to bother me, I would take it to a trusted tranny shop for a diagnosis.

The transmission mechanic I use has three general bits of advice:
1. Change the fluid regularly at 60K to 80K depending upon your driving. He says the transmission will last several hundred thousand miles if you do this.
2. Drive it until it breaks, because it costs the same to fix it either way.
3. If you are going to pull the tranny and have him rebuild it, bring the car in first so that he can scan the codes while it is in the car.
 

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1996 Eldorado
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A STS and a SLS I can't help to think they will behave differently as far as the transmission is concerned. If the difference is just "a little" as you stated, I would consider this normal with a gear 20% steeper in the STS.
 

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Discussion Starter #4
If I accelerate very slowly, the shifting is as smooth as can be. And if I punch it, the shift is also smooth. It's only mildly rough when I accelerate moderately. I'd say it's normal. I'll have the fluid exchanged in the near future. On the DIC, it says 99% for the trans fluid if that means anything...
 

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2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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Transmission fluid is not subjected to anything close to the contamination which engine oil fights on a daily basis. If you don't race, tow, or somehow overheat the fluid it will stay at 100% or 99% forever.

If you get paranoid, change the fluid somewhere between 50,000 and 100,000 miles. That gives you a LOT of leeway - again, under normal daily driver conditions, transmission fluid is forever.

Either get a real Helm/GM Factory Service Manual or subscribe your car to www.alldatadiy.com. For grins, get to the transmission sections (don't panic - huge) and find the various light, normal, and heavy load shift points for your car. (1-2-3 WOT shift points are at engine redline - period - and they should be crisp and/or hard.)
 

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Discussion Starter #6
It's a bad motor mount. I did the brake/accelerator test and the engine moves pretty considerably...I'd say over an inch of movement. I guess that would explain the hard shifting...I got screwed on this car.
 

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Discussion Starter #10
The front center motor mount checked out OK. In addition to a mechanic saying it's OK, I performed the brake torque test with my father in the driveway. He held a straight edge above the front of the motor. I shifted from P to R, and there was no movement. R to D, there was very minimal movement. When I applied the brake and gave it gas up to 1500 RPM, the engine twisted about 3/8 of an inch towards the firewall.

This brings up some other things now that the motor mount is OK...

I still have a rough shift sometimes, although most probably wouldn't call it rough (maybe I'm spoiled because my '97 SLS shifted flawlessly).
Second, at redline shift (6500 RPM) during WOT (In both 2 and D) I hear a belt screech or something...I have no idea what that could be.

Any help would be greatly appreciated.
 

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2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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It's not a belt screech - it's a tire chirp !

Under anything other than feather touch acceleration my STS definitely lets me know each shift point.
 

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Discussion Starter #12
Oh, lol....I feel stupid now :)

I guess my SLS didn't have the power at redline that this one has...
 

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2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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Power, tires, temperature, inflation pressure, road surface - all affect tire adhesion.

Here are the curves for 2000+.
 

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Discussion Starter #15 (Edited)
So this is definitely just tire chirp? I want to be sure because Goodyear told me I had a broken motor mount when I had alignment done (along with a bad wheel bearing and tie rod - which are fine), and Firestone just told me I had a broken mount yesterday when I had RFB done...He said the front of the car moves when you give it gas...(It's supposed to...??)

One mechanic said it was fine, I think it's fine (I tested - only about 1/4 inch of engine twist) and a Cadillac dealership changed the oil and inspected it and made no mention of a broken motor mount.

If there were a broken motor mount, would there be any sort of 'chirp' in the engine bay at redline during WOT?

Thanks
 

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2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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Post #6 says the engine moved over an inch. That's a broken front center motor mount.

This post ^^^ says 1/4 inch which would indicate that the mount is OK.
 

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Discussion Starter #17
Post #6 - I just took a quick look at it while someone else brake torqued it...

In the later post, I actually had my father hold a 4 ft. level across the engine bay just over the front of the engine. He said it moved 1/4 inch at the most.

I just want to be sure that it's only tire chirp I'm hearing...It's does it during WOT shifting from 1 to 2...With traction on and off.
 

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2016 Honda Accord LX. Previous: 2004 Deville, 2000 STS
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Motor mount's are oh so common on the '98-'04 Seville's. I had to get mine replaced the other day... the previous one lasted 6 months. I have a heavy foot... :sneaky: The motor mount I replaced was so bad when you gave the car too much gas it would make a terrible noise that sounded like the transmission was about to fall out (and that's what I thought had happened). Don't drive with a broken mount for too long because it can really mess the car up. Best way to check is get it up on a lift and inspect the mount. Mine had broken in half and the motor was resting on practically nothing for the most part. I've been going easy on my car for 2 days, but the urge to give it some gas is still there. :)
 

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Discussion Starter #20
I don't think it's broken..I'm sure the dealership would have noticed it at inspection/oil change.
 
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