DOUBT IT

iTrader: (13)

I was at the track last night, running really well, and I noticed that at the top-end, the converter seemed even looser than usual. As in, I was hitting the rev limiter just after I crossed the line.

I was wondering if ATF loses some viscosity after some mileage, and if I could mix in a quart or so of a different kind of fluid ( such as Type F ) to make the converter a little more efficient on the top end.

I want to see what all the tranny guys have to say.

FLT

iTrader: (1)

What were your tranny temps? The hotter the oil gets the thinner it gets. Might be something to think about especially if you were hot lapping it. I do not recommend mixing oil types.

DOUBT IT

iTrader: (13)

Not hot at all. I have a big-*** 24k GVW cooler on there. It never got over 170*

Does fluid wear enough over time that the viscosity goes down? It used to read 125 on the speedo before it slapped the limiter, Friday night it was reading 120.

The converter is a TCI SSF 4000, and I have 3.73 gears. Also, Gomer tuned for the converter, so I KNOW it's not a tune issue.

I'm thinking of just changing the fluid this weekend, and seeing where that gets me. You have any recommendations Vince?

FLT

iTrader: (1)

The oil can break down and a service might help. I would however advise dropping the pan to do a visual inspection to see if clutch material or debris from the converter are present. If so a service will probably not fix your problem. Vince

DOUBT IT

iTrader: (13)

Just for reference, I took the car out this evening, and found a nice empty stretch, and nailed it in third. The car still hits the limiter @ 120. This was with tranny temps at 130*

I got some fluid, I'm gonna change it and check out the bottom of the pan while I'm at it. I got Castrol ATF this time, instead of the cheapo Advance brand.

NHRAFORMULA00

iTrader: (2)

sounds like the tranny is slipping

DOUBT IT

iTrader: (13)

It doesn't act like it is. It still pulls fine, just acts like the converter is a little less efficient up top.

Actually, I guess that it isn't that far off, because the gear calculator lists my top possible speed @ 6000 rpm as follows.

1st: 40
2nd: 76
3rd: 123
4th: 175

Maybe it's just that my car is trapping faster than I consistently have before, as well as wore out fluid. *shrugs*

performabuilt

iTrader: (25)

If the shifts feel firm and the cars pulling up till that point I doubt the trans is slipping at a certain MPH and causing the car to hit the rev limiter. As suggested I would pull the pan never hurts to look. But there are many other things that can have effect on tuning and change how it works, Even though you had it tund and it may have been perfect at that time a sensors value could have changed or something along those lines also causing your present issue.

DOUBT IT

iTrader: (13)

I just thought of something. There is one bolt in the valve body that is completely loose. I mean, the last time that I changed the filter (March 2006) the only thing that was holding the bolt in was the filter. I hand-tightened it back up there, and meant to torque it back down, as well as check all the other bolts, but I had to get the car off the rack fast (I was at work on my day off) and forgot.

Could one loose bolt cause problems? And also, does anyone have the tightening sequence for the 4L60E valve body bolts? I already know that the torque figure is about 7 ft/lbs (95 in lbs)

Any help would be greatly appreciated, and Sunday morning, when I get around to changing the fluid, filter, and inspecting everything, I'm gonna take pictures, as well as drain the fluid through a coffee filter, just to be sure...

DOUBT IT

iTrader: (13)

Welp, drained the fluid and there was nothing out of the ordinary. Looked fine, smelled fine. Picked up only very small speckles of clutch material in the coffee strainer, actually looked better than the last time I changed my fluid, and that was before the converter!

I misplaced my Allen wrench, and couldn't find one to take the tranny pan down, so I couldn't inspect anything or tighten the bolt, but the fluid looked good, so I figure it's no big deal.

Took the car out, got everything warm, and the trans actually felt a little better. The overrun clutch is coming on quicker than before, so that's a good thing. But everything else, shifts, TCC lockup, felt smoother and more positive than before.

Traffic was too heavy, so I couldn't make a WOT 3rd gear run to see how that felt, but all in all, the trans seems to like the fresh premium fluid.

We'll see how she does at the track. I guess that the old fluid was just worn out. 10,000 miles of mainly hard street driving and drag strip abuse will do that I guess.