HighMileSS

Alright guys I'm new to the website and to the whole ls1 world. But I seem to have a problem with my car. It's 99 ss with an automatic transmission with 167k miles . It doesn't seem to want to shift in to 3rd gear at WOT. But every other gear will shift fine. When driving normal. All gears will shift fine. Just 3rd gear at WOT will not shift. It'll just bounce off the rev limiter. The speedometer is off 10 or so mph if that matters. Help and lead me in the right direction please

blackLS1m6

iTrader: (14)

Sounds like the 3-4 clutch pack is worn.

HighMileSS

Wouldn't it be the 2-3 If it was that?

blackLS1m6

iTrader: (14)

No because when the transmission is shifting from 2nd gear to 3rd gear it applys the 3-4 clutch pack, when that clutch pack is worn it wont be able shift into 3rd or 4th gear. Your trans has enough to shift into 3rd and 4th under normal conditions but under WOT it cant complete the shift or hold it in gear. Very common problem with the 4L60E.

HighMileSS

So how much would it cost to fix?

blackLS1m6

iTrader: (14)

At that mileage your looking at a complete overhaul. Depends on if you are going to do a stock rebuild or do some upgrades. You could also look around for a used trans but you never know what you might be getting. Check out the sponsors too RPM transmissions, FLT, Performabuilt etc.

HighMileSS

I'd prefer just a stock rebuild for now

mrvedit

While blackLS1m6 is right that a worn out 3/4 clutch is a common 4L60E problem and exactly matches those symptoms, your speedometer error might be the culprit.

Under partial throttle, the 4L60E shifts according to throttle position and MPH set in a tuning table. However under WOT, it only shifts when both the tuned MPH and the tuned RPM are reached. (These are specified in separate WOT shift tables.) If your MPH is relatively low, due to slippage of a high stall converter, or a defective speed sensor, you will hit the rev limiter before the PCM commands the shift.

Therefore, I would suggest getting the speedometer error checked first. You might borrow a scanner (e.g. from an auto store) and compare its speed to your speedometer. If it matches, you might have a bad VSS or related problem and should correct that first.

If the scanner reads 10mph higher than your speedometer, then just your speedometer itself is bad and you likely have a worn out 3/4 clutch.

Frankly, you probably do have a worn out 3/4 clutch as blackLS1m6 suggested.
How long have you had the speedometer error?
How long have you had the 2-3 shift problem?

If indeed the 3/4 clutch is worn out, the trans needs to be removed and completely rebuilt. Typical cost is $1500 to remove, rebuild and re-install. The shop may insist on a new converter or not offer any warranty; reason is that sludge from the worn out 3/4 clutch frictions can accumulate in the converter and cause future problems in the trans.

This thread really belongs in the Auto-Trans section. I will move it there in the next day or so. We have a similar thread there now:

https://ls1tech.com/forums/automatic...-flooring.html

HighMileSS

Thanks. This leads me in the right direction