700R4 Driving Characteristics
11-30-2016, 12:45 PM
#1
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Car: 1991 Z-28
Engine: 305 TPI
Transmission: AUTO
Axle/Gears: 2:73
700R4 Driving Characteristics
Hi, New 3rd Gen owner, I have just gotten my 91 Z-28 (5.0 TPI) through inspection and started driving it (YAY).
I have a stock 700R4 (120k miles) and am noticing some things with the trans operation but don't know if it is operating normally or not.
I have replaced the fluid and filter and added some Lucas Transmission Conditioner.
Under hard acceleration the 1-2 upshift is fine firm and quick. The 2-3 shift is softer and it seems like it "sllliiidddeeesss" into gear not really firm and quick but makes the shift fine, not sure about 3-4 shift under hard acceleration.
Under normal acceleration all shifts are fine.
Downshifts are generally pretty hard almost too hard.
At cruise in OD the trans acts almost like it is shifting in and out of another gear but not into third. (It almost feels like engaging disengaging a clutch) but when I get into the throttle it shifts firmly into 3rd and then into second with enough throttle.
Sorry if this seems like an idiot question but does this sound like the trans is operating like it should or should I think about rebuilding or replacing???
Car was sitting for 8 years and I am thinking it needs to be run, but just thought I would ask.
Thanks for any comments or questions.
I have a stock 700R4 (120k miles) and am noticing some things with the trans operation but don't know if it is operating normally or not.
I have replaced the fluid and filter and added some Lucas Transmission Conditioner.
Under hard acceleration the 1-2 upshift is fine firm and quick. The 2-3 shift is softer and it seems like it "sllliiidddeeesss" into gear not really firm and quick but makes the shift fine, not sure about 3-4 shift under hard acceleration.
Under normal acceleration all shifts are fine.
Downshifts are generally pretty hard almost too hard.
At cruise in OD the trans acts almost like it is shifting in and out of another gear but not into third. (It almost feels like engaging disengaging a clutch) but when I get into the throttle it shifts firmly into 3rd and then into second with enough throttle.
Sorry if this seems like an idiot question but does this sound like the trans is operating like it should or should I think about rebuilding or replacing???
Car was sitting for 8 years and I am thinking it needs to be run, but just thought I would ask.
Thanks for any comments or questions.
11-30-2016, 01:22 PM
#2
Supreme Member
Re: 700R4 Driving Characteristics
Hi, New 3rd Gen owner, I have just gotten my 91 Z-28 (5.0 TPI) through inspection and started driving it (YAY).
I have a stock 700R4 (120k miles) and am noticing some things with the trans operation but don't know if it is operating normally or not.
I have replaced the fluid and filter and added some Lucas Transmission Conditioner.
Under hard acceleration the 1-2 upshift is fine firm and quick. The 2-3 shift is softer and it seems like it "sllliiidddeeesss" into gear not really firm and quick but makes the shift fine, not sure about 3-4 shift under hard acceleration.
Under normal acceleration all shifts are fine.
Downshifts are generally pretty hard almost too hard.
At cruise in OD the trans acts almost like it is shifting in and out of another gear but not into third. (It almost feels like engaging disengaging a clutch) but when I get into the throttle it shifts firmly into 3rd and then into second with enough throttle.
Sorry if this seems like an idiot question but does this sound like the trans is operating like it should or should I think about rebuilding or replacing???
Car was sitting for 8 years and I am thinking it needs to be run, but just thought I would ask.
Thanks for any comments or questions.
I have a stock 700R4 (120k miles) and am noticing some things with the trans operation but don't know if it is operating normally or not.
I have replaced the fluid and filter and added some Lucas Transmission Conditioner.
Under hard acceleration the 1-2 upshift is fine firm and quick. The 2-3 shift is softer and it seems like it "sllliiidddeeesss" into gear not really firm and quick but makes the shift fine, not sure about 3-4 shift under hard acceleration.
Under normal acceleration all shifts are fine.
Downshifts are generally pretty hard almost too hard.
At cruise in OD the trans acts almost like it is shifting in and out of another gear but not into third. (It almost feels like engaging disengaging a clutch) but when I get into the throttle it shifts firmly into 3rd and then into second with enough throttle.
Sorry if this seems like an idiot question but does this sound like the trans is operating like it should or should I think about rebuilding or replacing???
Car was sitting for 8 years and I am thinking it needs to be run, but just thought I would ask.
Thanks for any comments or questions.
11-30-2016, 02:15 PM
#3
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Car: 1991 Z-28
Engine: 305 TPI
Transmission: AUTO
Axle/Gears: 2:73
Re: 700R4 Driving Characteristics
Pretty much all speeds. Primarily on a fairly neutral or level surface. I have been reading posts related to Lock Up converters and it almost feels like the converter is releasing and then locking up when it senses load. (or what I imagine this might feel like) but I don't have any basis for comparison.
11-30-2016, 09:31 PM
#4
Re: 700R4 Driving Characteristics
see bold for my answers
Hi, New 3rd Gen owner, I have just gotten my 91 Z-28 (5.0 TPI) through inspection and started driving it (YAY).
I have a stock 700R4 (120k miles) and am noticing some things with the trans operation but don't know if it is operating normally or not.
I have replaced the fluid and filter and added some Lucas Transmission Conditioner.
Under hard acceleration the 1-2 upshift is fine firm and quick. The 2-3 shift is softer and it seems like it "sllliiidddeeesss" into gear not really firm and quick but makes the shift fine, not sure about 3-4 shift under hard acceleration. seems about normal for a stock 700r4. 1-2 is a big difference in ratios. 2-3 will be softer unless you put a shift kit or bigger servo on it. the trans wont shift into 4th at WOT. i want to say it is half throttle or less for it to go into 4th.
Under normal acceleration all shifts are fine.
Downshifts are generally pretty hard almost too hard. it would be a good idea to make sure your TV cable is SET correctly. i say set not adjusted for a reason. the TV cable only has 1 correct position. some people "adjust" them for a better shift feel but that is a quick and easy way to ruin a trans. search around on the web or on here for how to set the TV cable. it is easy and only takes a minute.
At cruise in OD the trans acts almost like it is shifting in and out of another gear but not into third. (It almost feels like engaging disengaging a clutch) but when I get into the throttle it shifts firmly into 3rd and then into second with enough throttle. sounds exactly like the lock up in the converter. it shouldnt be going i and out if you are at a constant load though. once it locks it should only unlock when you press the gas a decent amount.
Sorry if this seems like an idiot question but does this sound like the trans is operating like it should or should I think about rebuilding or replacing???
Car was sitting for 8 years and I am thinking it needs to be run, but just thought I would ask.not stupid questions. you are learning about a new car. this place is an extremely good source of info. if you have anymore questions dont hesitate to ask.
Thanks for any comments or questions.
I have a stock 700R4 (120k miles) and am noticing some things with the trans operation but don't know if it is operating normally or not.
I have replaced the fluid and filter and added some Lucas Transmission Conditioner.
Under hard acceleration the 1-2 upshift is fine firm and quick. The 2-3 shift is softer and it seems like it "sllliiidddeeesss" into gear not really firm and quick but makes the shift fine, not sure about 3-4 shift under hard acceleration. seems about normal for a stock 700r4. 1-2 is a big difference in ratios. 2-3 will be softer unless you put a shift kit or bigger servo on it. the trans wont shift into 4th at WOT. i want to say it is half throttle or less for it to go into 4th.
Under normal acceleration all shifts are fine.
Downshifts are generally pretty hard almost too hard. it would be a good idea to make sure your TV cable is SET correctly. i say set not adjusted for a reason. the TV cable only has 1 correct position. some people "adjust" them for a better shift feel but that is a quick and easy way to ruin a trans. search around on the web or on here for how to set the TV cable. it is easy and only takes a minute.
At cruise in OD the trans acts almost like it is shifting in and out of another gear but not into third. (It almost feels like engaging disengaging a clutch) but when I get into the throttle it shifts firmly into 3rd and then into second with enough throttle. sounds exactly like the lock up in the converter. it shouldnt be going i and out if you are at a constant load though. once it locks it should only unlock when you press the gas a decent amount.
Sorry if this seems like an idiot question but does this sound like the trans is operating like it should or should I think about rebuilding or replacing???
Car was sitting for 8 years and I am thinking it needs to be run, but just thought I would ask.not stupid questions. you are learning about a new car. this place is an extremely good source of info. if you have anymore questions dont hesitate to ask.
Thanks for any comments or questions.
12-01-2016, 07:02 AM
#5
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Car: 1991 Z-28
Engine: 305 TPI
Transmission: AUTO
Axle/Gears: 2:73
Re: 700R4 Driving Characteristics
Thanks so much for the response.
I will take a look at the TV setting. Yes, at constant load, steady state, the trans is steady. I notice the "releasing" and "engaging" with small changes in throttle loading and unloading.
I only have a couple hundred miles on the car now and LOVE it, but am still nervous about the sounds and feel of the car. It would sure be a relief if I didn't have to work on the trans right now.
Thanks again this is a great forum and the members are very helpful!!!
I will take a look at the TV setting. Yes, at constant load, steady state, the trans is steady. I notice the "releasing" and "engaging" with small changes in throttle loading and unloading.
I only have a couple hundred miles on the car now and LOVE it, but am still nervous about the sounds and feel of the car. It would sure be a relief if I didn't have to work on the trans right now.
Thanks again this is a great forum and the members are very helpful!!!
12-07-2016, 07:56 PM
#6
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Car: Sport Coupe
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Transmission: WC T5
Axle/Gears: 3.42
Re: 700R4 Driving Characteristics
IF you aren't sure about setting your TV cable, find someone who can.
I can also tell you that when it starts rapidly shifting from 3-4-3-4 rapidly, your days are numbered.
I can also tell you that when it starts rapidly shifting from 3-4-3-4 rapidly, your days are numbered.
12-08-2016, 09:56 AM
#7
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Car: 1985 Pontiac Trans Am WS6
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Re: 700R4 Driving Characteristics
As for the 3-4 shift under hard acceleration, well, good luck getting it to do that XD. There are ways you can modify your trans to take more than 1/2 throttle in 4th, but I don't know the specifics. It doesn't sound like you have anything unusually bad with your transmission. Best of luck!
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12-27-2016, 05:23 AM
#8
Re: 700R4 Driving Characteristics
Yeah, the problem of them "searching" between 3rd and 4th gear when cruising is really common with the 700r4. There's a couple of cures for this. You can buy the B&M 3/4 downshift throttle valve, or look at the sticky at the top of this forum regarding the 3/4 throttle valve mod. The stock valve forces a downshift into 3rd, and the converter to unlock any time the throttle is pushed down any further than 2/3rds of the way, which is really easy to do even when just cruising down the freeway. Pretty easy mod to do. Just have to drop the fluid pan, and the valve is located at the end of the TV cable in the valve body area. One cause of hard downshifts is when the 1-2 accumulator spring either breaks or pushes it's way through the thin steel separator plate between the valve body and the main body of the trans. Dana at Pro-Built Automatics sells a reinforcement plate you can install that will prevent the accumulator spring from pushing through the thin steel valve body separator plate. My stock 700r4, before the rebuild/upgrades, had both problems: broken spring and pushing through the plate. If yours is doing this, get a new separator plate and the reinforcement plate. It's also a good idea while you're right there to replace the accumulator springs and pistons. All these parts are relatively inexpensive to get.
12-29-2016, 08:54 AM
#9
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Car: 1991 Z-28
Engine: 305 TPI
Transmission: AUTO
Axle/Gears: 2:73
Re: 700R4 Driving Characteristics
Thanks, I appreciate the comments and suggestions.
I am going to try a Transgo Junior Shift Kit as it looks like this may address Pat's suggested areas and see where it goes.
I have never been inside an automatic trans before and hope this will be simple enough for me not to screw up. (baby steps)
I am going to try a Transgo Junior Shift Kit as it looks like this may address Pat's suggested areas and see where it goes.
I have never been inside an automatic trans before and hope this will be simple enough for me not to screw up. (baby steps)
12-30-2016, 05:06 PM
#10
Re: 700R4 Driving Characteristics
Yeah, the TransGo Jr. shift kit is probably a good idea. Make sure to either buy the B&M 3/4 shift valve, or modify your own per the sticky in this forum. Shift valve should eliminate the going back and forth between 3rd and 4th, and going in and out of lockup. None of these mods are too difficult to do, so you should be fine.