1990lumina Posted July 24, 2005 Report Posted July 24, 2005 Well, over the last while my 90 Lumina 3.1 w/ 4T60 has been harshly shifting into reverse. I've been told to check the vacuum modulator, which I have yet to do. However, today, I was backing up onto the driveway like I always do, and when I got the front wheels to the sidewalk curb, (we have the rolled style), anyway, I gave her some gas to keep going, and all there was was a severe vibration and chunking. So I immediately let off the gas at which point it stopped vibrating. I then took a run at the durb (drive forward, put in reverse and give it gas, then let off and let it coast up the curb). Anyway, the fluid appears to be good, no burning. I dunno why this would have happened. The tranny has around 89700miles (144500km) on it. I hope I don't lose reverse and that this was some freak screw up internally. So far reverse is still working. I plan on checking this vacuum modulator thing sooner then later now as I think the harsh shift into reverse has worn it down... Any opinions, etc?? - Jeff L. Quote
z34_nut Posted July 25, 2005 Report Posted July 25, 2005 Well let me just say that reverse is the first to go. And I know from experience... Quote
1990lumina Posted July 25, 2005 Author Report Posted July 25, 2005 Fuck, that doesn't sound good... Guess I'll check this vacuum modulator thing ASAP before it finally screws the whole reverse gear. And I'll have to take her easy in reverse then. All the foward gears shift very nice and smooth which is why I was surprised when this happened. Thanks for the heads up though z34_nut! Quote
THe_DeTAiL3R Posted July 25, 2005 Report Posted July 25, 2005 Do you come to a COMPLETE stop with your brakes locked when shifting into reverse (not rolling 1mph or anything)? If so it shouldn't shift hard. If the engine revs are up at all with a plugged vac line/modulator then it will shift too hard. That's the way it was when I plugged the line on my 88 GP anyways.. Quote
1990lumina Posted July 25, 2005 Author Report Posted July 25, 2005 As an example. When I started her up after work today, I shifted it into reverse from a dead stop and it had the usual "CLUNK". This is of course when th engine is cold....and the revs are around 1100rpm instead of the usual 800 or so rpm. S this would go along with your theory of higher revs causing the harsh shift. When I drove home my dad was talking to some ppl on the driveway so I parked on the street, then after they left I backed it up onto the driveway..again, I started it up, and my engine takes like 40 or so secs to drop down to normal idle....so usually I just shift into reverse with no brakes applied (car isn't moving because this is a shift from "park" to "reverse"). Anyway, it clunked again because the revs were higher then usual. How much is this item to replace from the dealer? I looked at it in my Haynes manual tonight and it doesn't look like much. I'd like a new one rather then a j/y one.. Thanks - Jeff L. Quote
THe_DeTAiL3R Posted July 25, 2005 Report Posted July 25, 2005 If it's the 4T60 I think they're cheap, but not sure. I tried to find one for my 95 (4T60e) and they're hella expensive, most places didn't even carry them. Wish I lived in the country then I'd still have my 88 GP with a good 4T60 lying around... Quote
Robby1870 Posted July 25, 2005 Report Posted July 25, 2005 yeah, adjustable modulators are like $17 or something Quote
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