just picked up an 84 z28 and upon driving the car noticed that the tranny will not shift the gears unless you let up on the gas pedal.
then it does shift very strong as if it has a shift kit installed.
i have tried this from the overdrive position,or the low to drive manually.
no matter where i put the shifter it will not shift a gear until i let up on the throttle.
anyone got any ideas what this could be?
i know it's a dumb question but i am just getting into the newer camaros.
all the others i have owned were 400 turbo trannys,and this seems to me like a new game.

thanks guys for any help me can provide.
maybe give me some things to try,or some things to look for?

thanks again,
jd

you can reply to my email if you like.
msjdracing@rtmc.net

 

Re: 700R4 Automatic problems
You should really check you TV (throttle valve) cable. If that cable is not set properly it will affect your shifting.

 

Try replacing the throttle Position Sensor. I got that fix from:

http://www.carsurvey.org/reviews/che...mments/page-5/ scroll down a bit and you will find the reasoning and success behind it.

Richard.

 

rj,i sent you a picture of the 84.
it was taken tonight but looks better than
i thought it would.
jd

 

http://www.familycar.com/Transmission.htm suggests to check the following:

Governor, Vacuum Modulator, Throttle Cable
These three components are important in the non-computerized transmissions. They provide the inputs that tell the transmission when to shift. The Governor is connected to the output shaft and regulates hydraulic pressure based on vehicle speed. It accomplishes this using centrifugal force to spin a pair of hinged weights against pull-back springs. As the weights pull further out against the springs, more oil pressure is allowed past the governor to act on the shift valves that are in the valve body which then signal the appropriate shifts.
Of course, vehicle speed is not the only thing that controls when a transmission should shift, the load that the engine is under is also important. The more load you place on the engine, the longer the transmission will hold a gear before shifting to the next one.
There are two types of devices that serve the purpose of monitoring the engine load: the Throttle Cable and the Vacuum Modulator. A transmission will use one or the other but generally not both of these devices. Each works in a different way to monitor engine load.
The Throttle Cable simply monitors the position of the gas pedal through a cable that runs from the gas pedal to the throttle valve in the valve body.
The Vacuum Modulator monitors engine vacuum by a rubber vacuum hose which is connected to the engine. Engine vacuum reacts very accurately to engine load with high vacuum produced when the engine is under light load and diminishing down to zero vacuum when the engine is under a heavy load. The modulator is attached to the outside of the transmission case and has a shaft which passes through the case and attaches to the throttle valve in the valve body. When an engine is under a light load or no load, high vacuum acts on the modulator which moves the throttle valve in one direction to allow the transmission to shift early and soft. As the engine load increases, vacuum is diminished which moves the valve in the other direction causing the transmission to shift later and more firmly.

Richard.

 

Try putting 'Controllling Shift Quality" into this website 'find in page'

http://www.montecarloss.com/SSThunder/drivetrain.html

and you will find:

Controlling Shift Quality
In automatic transmissions, the Governor, Shift Valves, and Vacuum Modulator, work in unison to select the proper gear. In light throttle conditions, very little hydraulic pressure is needed to apply the bands and clutches. As load increases, higher hydraulic pressure is needed to apply the bands and clutches to change gears.

Automatic transmissions monitor engine load with a TV valve or modulator to get information for shift timing. The valve body uses this information to adjust the hydraulic pressure, to compensate for varying engine loads. The pressure regulator valve has a spring "pushing" on one end of the valve, and hydraulic pressure "pushing" on the other end of the valve. When the hydraulic pressure is high enough to overcome the spring pressure, the valve moves, and bleeds off the excess pressure.

The Throttle Pressure Valve, or modulator, helps the pressure regulator valve, by varying fluid pressure depending on engine load. This pressure coming from the modulator, is directed to the pressure regulator valve, and helps the spring "push" on the valve. This makes the spring seem stiffer, hydraulic pressure must be higher, to overcome the increased pressure, caused by both the spring and the throttle pressure helping the spring, before the valve can bleed off the excess pressure.

In this way, hydraulic pressure increases with engine load. By the way, this hydraulic pressure is commonly referred to as "Main Line Pressure", and it varies, from transmission to transmission, but tends to be around 50 or 60 PSI at an idle, in neutral, and may go as high as 250 PSI under certain highload conditions. This accounts for some of the shift-quality-improving characteristics of a modern automatic transmission.

There are other ways, commonly used in conjunction with main line pressure "altering", to improve shift quality. One way, is to provide a restriction, in line, to "slow down" the application of the friction components. The fluid must pass through a small hole,or orifice, before applying the friction component, similar to "pinching" a garden hose, to slow water flow, thereby filling a bucket with water more slowly.

To further cushion the shift, engineers often incorporate Accumulators. An accumulator can be, as simple as a piston with a spring on one side. When a shift is commanded, hydraulic pressure is routed through an orifice and into a chamber, acting on one side of the piston (the side of the piston, opposite the spring). This hydraulic pressure "pushes" on the piston, compressing the spring (on the other side of the piston), and "absorbing" some of the hydraulic pressure that is also acting on the friction component needed to create the desired gear change. This acts to "slow" down the application of the friction component, and smooth the application, and make the gear change less harsh.

I am almost convinced it is a sensor, but then I don't know what transmission it is, etc.

Richard.

 

thanks for the help man,i really appreciate it.
i will check it out and see what i can find.
my last fix for the stick shift car was a fuel
pump and idle sensor.
i got the fuel pump with lifetime for 55.00.
idle sensor was 32.00 i think.
now i have noticed that car will cut off if you
come to a quick stop with the clutch to floor.
jd
p.s.i guess it's meant to be?
go from stick shift to automatic?
i still rather drive the stick shift.
i am looking for a nicer one than i
have if anyone has a nice one to
sell,or trade?
i think i have my anniversary automatic sold.

 

The car had been sitting awhile.
Seems the more I drive it the better it gets.
Is there any good Tranny conditioner out there to put in the fluid to make it last longer,or shift better?
I don't want to put anything in there to hurt it?
Is LUCAS tranny stuff a good idea?
How about in my oil,and gas?
Since car has been sitting I just want to know should i do any of the above?

Thanks again for everyones suggestions,
jdracing

P.S.just picked up another 92 rs saturday.
Needs fuel pump.It also needs the fx behind rear passenger tire,bottom quarter.92 RS.

 

Hey JD! appropriate time to post about cars that have sat for a while.

My 85 sat for 4-5 years, got some awful quotes from reputable brake shops, but found the best deal in a service station who looked at the car for me before I bought, and I got the front brakes fixed for $221, needed new brake lines from the chassis to the caliper and rotors. I go back to get the rear brakes done for $259 on Wednesday. Other quotes were $850 and $1150. Brakes evenly now, no pulls.

The owner has had a lot of old cars, and said sitting does not do much if any damage.

The worst is a car sitting on grass, as moisture underneath promotes rust, rust and more rust.

The paint will oxidize, which is an easy fix using a color restorer, then polish and protect it, mine was just that easy.

Next up, after the rear brakes, is to replace the console lid, black, do you have one?

Next will be driver and passenger door weatherstripping, as well as T-Top weatherstripping.

Also on the list is ground effects, behind the grill fog llights, power window complete, except for windows, of course, power locks, power antenna, replacing front hood pistons, and rear hatch,

Got any of this stuff? maybe I turn out to be a parts customer of yours!!!

Forgot this, need to replace my plastic dash on the passenger side, and the dash top, and would like to get A/C, so need that complete.

Are you buying and selling 3rd gen camaros, exclusively?

Richard.