th 700

[adey]

i have a 84 silverado with a 700r4, this was rebuilt by the last owner around a year ago. i am experiencing a problem with it shifting up and down from 3rd to 4th at 40-50mph. this problem is intermittant and is only occuring around 20% of the time, in this mph range. has anyone any idea as to what this may be? hopefuly it is nothing serious as it is intemittant, any help would be most welcome.

[Robyn]

I am not quite sure with how you are describing your problem.

Does it just shift up and down rapidly or just go along and shift for no good reason.

Are you sure its not the converter locking and unlocking??

Give me some more info and we will go from there.

Robyn

[adey]

robyn

yes the auto shifts up and down repeatedly, as if it is unsure as what gear to be in.this can be intermittant, .i drove it this evening and it did not play up. however another time it is awfull to drive , cheers adrian

[john8662]

Could be the TCC unlocking.

Suggest checking the adjustment of the TPSwitch, which is located on the side of the injection pump. These switches do fail.

As a troubleshooting technique the next time the thing acts up. Pull-over and unplug the connectors to the switch and then go for a drive. You won't get a locking torque converter. If it still feels like it's shifting on the top end again, it's something else.

J

[Robyn]

When you drive it next and it starts it little thing, try just touching the brake pedal lightly (Just enough to activate the switch) all the while keeping the throttle steady.

If it stops doing it its the Converter clutch, but if this does not help then its actually shifting between 3-4.

Could be a throttle pressure cable issue or a more serious issue inside.

WHEN WAS THE FILTER AND FLUID LAST CHANGED??? Plugged filter????


Another thing you may want to do is get yourself a transmission pressure test gauge and hose.

Hook it up to the main pressure tap on the tranny and run the hose up and into the cab so you can watch it.

You can then watch whats going on during actual operation and see what the line pressure is.

You could be having the beginings of an input shaft failure. (The early 700's were notorious for this) What year is your 700? Original?

Does it do it more when hot than cold?

Give this a go a let us know what happens.

Robyn

[adey]

hi guys, i am pretty confident it is a faulty tps switch on the throttle body now. do you have any idea where i could buy one, napa will not allow me to purchase one as i am outside the usa. i explained that i would onnly need it to be shipped to chicargo and my freght forwarder would deliver it to me in the uk.Paypal or visa would not be a problem

chhers adrian

[SimonUK]

Hi Adey,

I use American Autoparts over here

http://www.americanautoparts.co.uk/home.htm

They will probably have the part you need in stock. If not it will only take a couple of days for the part to arrive at your door.

I've called them at 3 in the afternoon and the parts been delivered before 11 the next morning.

Longest I've waited is 4 days for stuff to come frome the states.