WOT = no Overdrive anymore?

[camarosource]

1992 Camaro Z28 with a 7004r (with Transgo shift-kit).

Recently I discovered that it doesn't want to shift to (I believe is overdrive) when I floor it; just goes into the redline).

I can shift into each gear without any problems

- Park = no problems
- Reverse = No problems
- DRIVE = No Problems
- Overdrive (D) = No Problems
- 2nd Gear = No Problems
- 1st Gear = No problems

They all appear to work fine. If I put it into DRIVE and then shift into (D), it successfully lowers the RPM's so that seems to work.

HOWEVER if I WOT, the tach just goes into the red and doesn't shift out 1 last time to decrease the RPM's like it used to.

WHAT can this be? A clutch? Pad? Throttle Linkage? or could this mean my Valve Body is GONE and needs replacing? (which I assume means I have to buy another shiftkit?)

The transmission was rebuilt twice already:

- Shift Kit
- Gasket and Seal set
- 9 Friction plates replaced (Kevlar)
- 9 Steal clutch plates were replaced
- Band H/D replaced
- Bushings replaced
- TV Valve replaced
- And a re-manufactured torque converter replaced

This was all done in 2006 (8 years ago)

What type of $$ are we looking at and what do you think is the problem?

Thanks

[Obsessive Camaro Disorder]

http://www.thirdgen.org/overdrive-au...c-transmission

Doesn't sound like anything is wrong.

[camarosource]

OK so I've come to the conclusion according to the description of what OVERDRIVE IS, I was WRONG in what I was describing.. So let me start over knowing this.

I believe it's gears 3 into 4 is the problem.

So basically if I am at a stand still [driving in OVERDRIVE "(D)" ] and I casually drive away, gears 1 -2 seems fine, 2 - 3 seems fine, and 3-4 seems fine. However if I am driving and I FLOOR IT, it shifts normally, but it REDLINES into 7,000 for approx 3-5 seconds BEFORE the tach jumps down (assuming that is gear 3 INTO 4). NEVER used to do that! I was NEVER in the RED when I floored it.. The tach just dials right into red with no stopping.

So I took it into my local Chevrolet Dealership and the transmission specialist of over 20 years takes the car out and gets into the freeway with me in the passenger seat.. We're doing like 80km/h and he FLOORS into and the tach needle continues into yellow and then into red.. if it removed his foot from the pedal it will shift. If he waits the 3-5 seconds (in red) it will then shift one last time. Course it's hard to get that much time on the freeway with cars around.

HERE IS THE CONCLUSION HE SAYS:

- There is NOTHING wrong with the transmission. The engine is working perfectly as well.
- He says the INSTRUMENT PANEL is the problem (tach to be more precise) and have removed it and already sent out for repairs. ($500)

NOW... I am UNABLE to understand what the tach needle has ANYTHING to do with shifting. Now I can understand if the needle is either NOT moving, or as he states it's moving too quickly into red when it's not actually anywhere near red... But HOW can the tach only do then when you FLOOR IT and it's going from 3 into 4th gear. How can the problem ONLY occur at that specific instance? I would THINK that if the tach is having issues rotating the needle the correct amount for acurate readings, that it would show for EVERY GEAR would it not?

And with a instrument panel sent out for repairs WITHOUT a car.. HOW can they possible fix it when they can't see what's happening during that SPECIFIC INSTANCE? It's not like the needle is NOT moving at all in which case that's easy to see and fix..

Am I being taken?

Thanks.

PS. I might be under the wrong assumption to WHICH gear as I am rather confused with the whole transmission gearing system ;-)

[camarosource]

If OVERDRIVE means 4th gear and the car is not supposed to go into 4th at WOT (which that is what I've been reading), then perhaps I should mean 2 into 3? WHATEVER the last year would be that shifts at WOT. :-)

[Obsessive Camaro Disorder]

I wouldn't say your being taken. Tachs in 92 are known for going bad but I would have checked it before i sent it out. I have a 92 and fixed my tach last winter for under ten bucks. Here is a link. Only try if you can solder. http://www.thirdgen.org/techboard/el...meter-fix.html . I was revving to 7 grand too.

[dollar14]

best i remember dealing with the 700r4 in my 1990 chevrolet truck,anything over half throttle in 4th gear would make it downshift into 3rd. i found out B&M made a 700r4 kick down valve that allowed 3/4 throttle in 4th gear without downshifting into 3rd allowing more top end speed which is what i was after.pick one up at jegs or summit about 30 bucks.you have to remove the valve body and replace the stock one with the new one.its a aluminum sleeve about 5/8's dia. by about 2-1/2 in. long with some holes and notches in it.

[Obsessive Camaro Disorder]

What is your rear gear and rear tire size?

[Sp00ner]

Isnt 'overdrive' in a 700r4 torque converter lockup?

Been a long time since I had mine...

[376LS3]

Take some pressure tests. We just put a 700R-4 in my dads 69 Camaro and it was a bitch to setup. Will it shift if you shift it manually? My '87 IROC tach needle is way in the red before it shifts. I wouldnt hold too much truth to what they read.

[eymang]

You say your tach rpms redline but do your hear your engine rev up to 7K? There are some tach gauge issues with the gen3. http://www.thirdgen.org/techboard/el...aayyy-off.html

[Obsessive Camaro Disorder]

Originally Posted by eymang

You say your tach rpms redline but do your hear your engine rev up to 7K? There are some tach gauge issues with the gen3. http://www.thirdgen.org/techboard/el...aayyy-off.html

Yes, its very common with the 90-92 tach. i posted the link to the 90-92 tach repair above. Like i said its very easy if you can solder. Its a sticky on TGO's electrical board.

[camarosource]

I understand the reports above of is being a resistor or something out.. But to me I cannot see how this is the reason.

Correct me if I am wrong.. if there is a problem with the tach displaying the needle WAY too high WOT, then HOW is it that it's ONLY on WOT when the last gears are shifting?

I would think every single gear was be racing way off and be completely too high but this is not the case.

I am idling at 800-1000 which is normal for me. My tach moves what appears normally during 1-2 and 2-3 shifts..

[Obsessive Camaro Disorder]

WHAT IS YOUR REAR END GEAR RATIO??? STOCK REAR TIRES??? i can be more helpful if you tell me this. http://www.thirdgen.org/calculations Use this to determine how fast each gear should be. Use the first calculator, there is a chart with your trans ratios at the bottom.

No, the tach isn't the reason for the tranny. they don't affect each other. We are now talking about two issues. My tach looked completely normal to me. It appeared to idle and rev completely normal but it was further off the higher it revved. I thought it was awful strange my 305tbi was pulling all the way to 7k before it felt like i should shift. ALL 3rd gen engines (that haven't had significant air flow mods) run out of breathe before 5k. So although the tach isn't affecting your trans you should still need to consider it may need repaired. You can check it with a timing light that has rpm. Or you can pull the chip and check the resistance with an ohm meter.

Have you read the link i posted above in post #2? I'm still not convinced you have a tranny problem. If all the other gears (1-2, 2-3/D) shift normal under WOT but it won't shift 3/D to 4/OD under WOT, that is how GM designed it. If you let up to 3/4 throttle does it shift to 4/OD? and then when you WOT again downshift back to 3rd? You should be able to do about 120 mph(5500rpm) in third at WOT if you have 3.42 gears. You and a mechanic took the car out and went that fast to see if it shifted to 4/OD under WOT?

[camarosource]

STOCK 3.23:1 REAR and 275/40zr17 all around.

I don't get how I am supposed to fill out the calculators. I am based in Canada so we don't use MPH. Also, The calculator seems backwards.. It's trying to give me the MPH that the shift should occur but I thought we're looking for what RPM (tach) when each shift should be occurring.

Rather confused here..

And as mentioned before, please IGNORE what I originally posted about WOT and O/D.. I was under the impression that O/D was the 4th gear and was the last gear that I would see shifting at WOT right away..