I recently purchased a 1999 Z34. The transmission shuddered badly so I had it rebuilt before I really drove it much. Here's the question... under normal/light acceleration, at what MPH should I see a third to fourth gear shift? I have a 96 Lumina (3.1, 4t60e) that shifts from 3-4 at about 35-40 MPH. The Z34 (3.8, 4t65e) shifts 3-4 at about 28 MPH. Not talking TC lockup here, just 3-4 shift. That feels too early to me. Tranny shop says that tranny checks out normal.

 

Your car will shift into fourth as early as it possibly can because that's overdrive and it saves the gas mileage.

If you HATE it, you can tune the shift points to change

 

I wouldn't say I hate it, but it is annoying. Just seems like it shifts too early. I was just curious to hear from other owners if that's what they experience. Didn't know if it's shifting at the correct factory setting, or if my car is doing something the factory did not intend. I thought about taking it to the dealer, but I'd probably just have a service advisor tell me that it "seems ok" or that there are no "codes" stored, or worst case - pay a $85 dx fee to tell me that there's no issues.

 

Doesn't sound like there is an issue to me. Why do you find it annoying??

 

It bogs the motor down somewhat. Feels like it lugs in 4th till you get up to about 35-40, which is where I'd rather see a shift. It's like the 6-speed skip shift....... yea it works, and maybe it increases mileage, but who drives 28 mph in overdive? Causes the tranny to flip back and forth between 3rd and 4th if you try to drive around 30mph too

 

I know what you mean... I would say just a quick tune to move those shift points would really be your benefit, until then just have to deal with it

 

i just drop it into drive unless im on the highway or a long straight road, then i pop it into OD once its up to speed with traffic.

even though i have the same driveline as your lumina, my car likes to dump into OD asap even if im driving around here, alot of curves and hills so alot of braking then throttling up. im not worried about if its gonna make it last longer, its just annoying to have it drop into OD goin up a hill and have to stomp it to get up the hill better.

 

chibiblacksheep - when you suggest a quick tune to move the shift points, what are you referring to? Is that the PCM? I've heard about reprogramming the PCM - is that what you are referring to? If so, who can do that? I'm not doing any mods to this car, so I don't need any complicated reprogramming, I just want a slightly higher rev/mph on that one shift.

 

28 MPH for 4th gear does not seem normal at all to me. My Monte will slip into 4th at 37 mph if i'm not on the gas much, and that puts me at 1,000 RPM, which is reallly low. I've never heard of any car going into 4th at 28 mph.

As a general refrence, here are the LOWEST 4th gear shifts for all the cars in my house:

-The Monte 3.5L 37 MPH
- Bonneville 3.8L 45 MPH
- Silverado 5.7L 38 MPH
- Solora 3.0L 40 MPH

I just don't see how its possbile for it to shift into OD at 28 MPH, and that is considered normal. I highly doubt it came that way from the factory when it was new...

 

Mine will shift into OD at 45 and no sooner but I think the gear ratios are different in the transmissions they put behind the LQ1s. I dont know what the shift points are in the other transmissions.