I've read a bit about this on the boards already. I've adjusted my TV cable twice, once to the procedure in Haynes, once to a procedure I found on the board. Driving WOT, I wind it up to basically 5000, and then end up letting off a little before it will shift. I know shifting to Overdrive you have to be below 3/4 throttle, but this is happening every gear. I've heard about a governor that might need to be changed, I've heard my TV cable might be sticking in the trans(?). Also, another random question. What exactly is a "Corvette servo" that I seem to read all sorts about? Thanks, -Dustin

I had the same problem. In my case it was a sticking valve in the governor. I had to replace mine, cleaning didn't help (probally a burr). Works fine now. It is probally not the tv valve or cable adjustment. Tv system controls line pressure to the clutches based on engine speed. A miss adjusted tv cable would slip the clutches, expecially during shifts. based on my experience. A corvette servo is a piston with a larger apply area for the 2-4 band. It has greater holding power. It replaces the servo in normal 700R4's. Jetchip.com has a servo with a larger apply area than the corvette servo. About $80.00 I believe.

brl90Iroc

Mine was doing the same thing. I pooped the TV cable out 1 more notch and it fixed it. TV cable too tight = late shift, TV cable too loose= shift too soon

The thing is that it seems to be shifting normal at part-throttle, at least nothing that I notice out of the ordinary. Shift to OD at about 40-45 mph under part throttle, which seems consistent with what I've heard from others.

Maybe it's shifting where it should, but I think it's too high? I know the TPI is done making power by 5000. Yesterday I left it in Drive, and under WOT shifts happened at about 5200 RPM, which doesn't make sense to me.

If I try to manually shift, the times I have tried I shifted from 1-2 at 4000 RPM, and it stayed in First until 5000, when I let off a little and it then finally shifted to Second. What would that indicate, or is that normal?

-Dustin

on thing to keep in mind about the 700R4/4L60 trans is that shift points are set by the governer. never set your shift points by adjusting the cable. adjusting the cable is done only because it has to be correct to keep line rise correct. if your shift points are too high simply swap governer's out for another one or change the weights/springs to your own choices of shift points. my 86 IROC that i had shifted at 5200 on the 1-2, 4800 on the 2-3, and 4900 on the 3-4 at w.o.t.. an 86 tpi stock was done long before it ever hit that rpm so as you can imagine it slowed it down, but that's how it was from the factory. my fix was just to put in a bigger cam and make it turn the rpm. manually shifting won't fix that since it won't shift lower than the governer's settings, just higher. as for the servo, the billet version made by superior which is sold under many other brand names is the one to go with. it has a much larger apply area and is machined much more accuratly than the stock one's. they are the only way to go. here's what you're looking for there.

I agree with Zippy, do not change your TV cable setting to correct a shift problem. It's a good way to lunch a trans well before it's time.

It's a spring problem in your governor. If it was shifting right before, you probably lost a spring off the governor altogether (BTDT). It happens if you race a lot. Be very careful what spring you install because it will change all your shift points. Try to put the stock one back in...... When in doubt as to the color of the reamining spring. Change them both out.

Lighter springs = Later shifts. Lighter weights on the governor body = later shifts.

I have heard nothing but bad things when people adjust their TV cable to set shift points, so I am not going to do that.

Like I said, part-throttle shifts seem to be fine, but I don't know if the shift points WOT are normal from a factory 700R4 or if it is out of whack at all.

If I change my governor springs to heavier so the tranny shifts in it's powerband, will my part-throttle shifts then be super-low?

-Dustin

part throttle won't change much. i'd recomend buying the b and m kit (just because it's the lowest price kit for this) and trying different combinations until you get it how you want it. changing the weights and springs both allow you to adjust not only the wide open shifts, but change the part throttle shifts a bit also.

It is best to set the tv cable to the factory specs and leave it. If it is not set properly you will slip the clutches.

Before you try to change the shift points by changing weights or springs you should ensure the governor is working properly. Most likely it is a stuck piston or a broke/missing spring. Check for stuck piston by holding the weights together and shaking back and forth. Piston should slide freely. Even if piston moves freely, I would remove pin from gear and slide out piston, clean and replace to ensure no particles are in the bore. Check to see if both springs are in place. If it worked before, it is not a shift point problem due to incorrect weights or springs. Something is stuck or broken.

Barry

Thanks for the advice. Anyone have pictures or other Tech articles on this, since I've never done any trans work at all before?

I can't say if it has ever "worked before", since as long as I've had the car(about 3 years), it's always been the same. I've just haven't ran it WOT hard very much

Finally, what are the shift points that you guys have stock? I can't think that 5200 or so from 1-2 would be set factory, but maybe it is.

-Dustin

I would like to change the govenor in my tranny but I'm just not sure which automatic tranny I have. I have an 87 firebird with the 2.8L V6. How would I find this out guys



Knight75

with 87 f-bodies you had your choice of automatic's. 700R4 or 700R4. i'm guessing you have a 700R4.

Sweeeet!

Thanks ZIPPY!:hail:



Knight75

Ok, so where is it supposed to shift at?
Mine runs up to 5K like Dwillms before it shifts.

shift points very by the engine. what are your specs?

Mine is an 88 305TPI, came stock with 3.23 gears but now has 3.73's.

if you're still running the stock cam and intake, i'd recomend shift points to be around 4800-4900 for the 1-2 and 4600-4700 for the 2-3.

4800-4900 seems to high since it stops pulling after 4500. Everything is stock except for a K&N cone inplace of the stock canister.

And I have a 86 305 TPI with weak-suck 2.73's, looking to switch to 3.23's. Any idea what STOCK shift points would have been, and what shift points I should be aiming for, stock cam/intake?

-Dustin

go with 3.42 or 3.73. I went from 3.23 to 3.73 and the car is much snappier off the line and from a roll.

i forgot yours being the pontiac version the air intake does lower the rpm range a bit, but you need to pass the peak power point in first to get it to not bog on the shift caused by the low stall of the converter and the high gear seperation (3.06 first and 1.63 second). i would say ideal for that car should be 4800 and 4600. in a third gen the ideal daily driver gear would be around a 3.23, but a 3.42 also works well, just with more highway rpm. 3.73 isn't bad, but once you go that far unless you're going to add nitrous or boost, you might as well go 4.10.

unfortunatly, the stock shift points on the 86 were around 5200 for the 1-2 and 4800-4900 for the 2-3 and 5000 for the 3-4. they were constantly complained about during magazine testing for being too high and it wasn't changed until 87. i've owned an 86 LB9 car myself that i had bought with 38k on it and not only did the high shift points slow the car down, but they gave me more reason to put a cam in it. a friend of mine has a car lot that sells alot of 3rd and 4th gen f-bodies and every 86 i've driven (with LB9) has the same problem. if i can scan some of the older articles i'll point out the issue. with the stock cam in an LB9 86 and newer (automatic version), the shift points i've found were best was 4800 and 4600. much lower seemed to allow it to fall on it's face and bring on knock retard for a few seconds and more just ran it out of breath even worse.