JrRifleCoach

My 86 coupe seems to hang (about a second) at high rpm before shifting 1-2. Although this makes for an impressive 2nd gear shift, I'd can't believe this makes the best use of power during hard acceleration runs. Can this hang be adjusted out or the 1-2 shift changed to a lower rpm? If so, can I accomplish this with standard tools?

:cheers:

TIMSPEED

Try adjusting your TV Cable...It takes a while to shift at part throttle, or does it just shift high (round 5200rpm) at WOT on the 1-2 shift?

BIG JIM 54

I know what you mean....

My '87 did the same thing. The shift points were higher than the engine wanted to rev. It would pull hard to 4900 RPM or so then fall flat on it's face then finally reach 5000 RPM or so and then shift to second. And it only did that on the 1st to 2nd shift.

Adjusting the TV cable doesn't work because if you do get the shift points right in the 1-2 shift, all the other gear shift points are screwed up. I been through it all and it's very frustrating. And every Corvette guy you talk to thinks you're crazy. This is evident by the number of responses on this forum as well.

The problem is the engine isn't breathing as well as it once did. It's running out of air. And a K&N with a cut lid, air foil, etc- none of that helps. Even a Hi-po cam doesn't help.

The problem is in the induction system. Since it's right on the edge, replacing or porting any of the parts in the induction helps greatly. A friend of mine just replaced the runners on his C4 with good aftermarket ones and his problem went away. I ported everything from the heads on up and my prob went away. And I still have to stock runners as I was going to replace them later instead of porting them. This lead me to the conclusion that anything you do to increase airflow above the simple stuff cures the problem and allows the engine to rev up at least to the point that the tranny shifts.

Don't ask me why some cars have this problem and some don't. If it happened to every older C4, we wouldn't get such dumb-founded looks from mechanics when we explain the problem. It could be the tranny raises it's shift points gradually I thought. But my '85 Z51 had the same problem brand new only not as bad.

There might be other cures, I don't know. But I couldn't find any.

Hope this helps,

BIG JIM

LT4BUD

Not sure if it is the same thing, but on my 89, the Corvette Action Center explained there was a race between the rev limiter and the 1-2 shift point.

They are nominally set only 100 rpm apart, which turned out not to be enough considering various environmental conditions & manufacturing tolerances.

Sometimes mine would just "hang" at the shift point for a second or so, other times it would shift just fine.

Sorry I don't recall if there was a recommended correction.

65Z01

You can try adjusting the TV cable toward the firewall a few clicks but when you go to WOT the throttle linkage may pull it back to the prior seting. To do this deperss the tang on the side of the TV cable bracket and move the cable slightly.

The real way to adjust WOT shift points is to change the weights & springs in the governor on the left side of the tranny. B&M makes a recalibration kit for just this purpose.

I had my A4 rebuilt with performance parts, a shift kit and shift points raised well into the 5k RPM range and now there is not "lingering" on the shifts.

JrRifleCoach

The real problematic area is at the 1-2 shift @WOT. I've tried adjusting the TV cable. It seemed that the shift point always came back to the same place. The other spot that feels really weird is WOT at a speed when 4th is starting to pull really good and then it shifts down to 3rd. Lift a little bit and its back to 4th, but now you've lost momentum and the revs drop, so the darn thing goes down to 3rd again....... and the Mustang pulls away (waaaaaa :cry )

Big Jim 54, I'm thinking that the intake/fuel system probably needs a good general cleanup. Fresh K&N, clean the TB, check fuel pressure and new fuel filter. And maybe another TV Cable adjustment attempt.

One item mentioned by 65Z01 is the B&M governor spring/weight kit. Since the tranny has 110k on it, maybe things have just gone out of calibration? :skep:

Can this be?


[Modified by JrRifleCoach, 10:16 PM 11/3/2003]

ENGINE TROOP

:iagree: with 65ZO1
To properly chang the wideopen trottle shift points you need to adjust the govener in your transmission.

larrybsp

I had this same problem with my 86 Z51 automatic. I solved it by going to a transmission shop and swapping out standard GM 700 R4 governors until I found the one that shifted where I wanted it. You want to shift so that the next gear puts you just below the peak engine torque rpm.

dtorc4

I've always been told not to mess with the TV cable. If you set the TV cable out of stock adjustment, it can mess with the transmission line pressure too much and really screw things up inside. I'm not a tranny guy, so I don't know exactly what happens, but I've been told it's not good.

JrRifleCoach

To throw another wrench in the works...... I detected an obvious slipping sensation during the 3-4 shift. If one lifts slightly at this shift past 45mph, the tranny can be convinced to lockup.

Looks like my winter project has yet another big expense. :banghead:

Im not heavy into drag racing, would like to get back into Solo II. Any sugestions for replacement transmissions? B&M maybe?

TIMSPEED

If you're up for a drive, I'd go up to Walnut Creek, and have them build you a nice 700R4. I know a guy who had one built...it went in his 650rwhp NOS'd ZR1..yes, he swapped out the ZF6 and put in the 700R4 built by Walnut Creek Transmissions's. BTW: He's running a 5000:eek: stall converter. I think they wanted like $1500 for the nice 700R4...When my new motor goes in, I'm DEFINATELY going to them. Because if they can get a 700R4 to live behind that kinda power, and continual 10 second passes at the drag strip, then it MUST be strong. :thumbs:

ICANTDR55

JrRifleCoach, I had the same problem with my 87. I tried everything in the above responses. The thing that will fix your problem will be to get the cal. kit for the govenor from b&m. It may take a few times to get it right but it will be worth every min. My 1-2 shift bangs at 4900 rpm every time after doing the mod. Even if I pull it down to low it will shift at 4900. :yesnod:

JrRifleCoach

Someday we need to meet :cheers: Until then, Id like to talk to shop down by the bay. Gotta name/address?


[Modified by JrRifleCoach, 10:13 PM 11/5/2003]

JrRifleCoach

I agree. The post regarding intake/porting is well worth noting when the trans is optimal. Those notes will definately be opened from my archive when the motor is pulled next year for internal mods.

Thanks all!

Southern Comfort

:nono: There is no true TV cable adjustment. It is setting the cable at the correct position. There is only one place the cable should be set. Go here for directions if you dont have a Shop Manual. Kind of like set it and forget it.
http://700r4.com