prokilllsx

We've been chasing this issue for a while now. Swapped converter, swapped valve springs, swapped cam, valve springs again, valve seals, etc., etc. etc.
Car falls off pretty hard at 5800 rpm when trans is cool, sooner the hotter it gets. On the dyno, the tuner can see a slight spike in rpm as the hp flatlines. It originally started at 6200 rpm, back in the spring. It has progressively gotten worse. Used to hold 471 rwhp before slipping. Now will only hold 456 rwhp at 5800 rpm.
Tuner says the clutches won't hold the power. We are planning on a performabuilt level 3.
Has anyone here seen this problem before and know what it is?
fuel, spark, signal are all where they should be.
BTW, thanks Brian Tooley for an amazing cam and Edge Converters for a ridiculously awesome 4000 stall!
The SS drives tremendously better than before. Throttle response even at 5% is unbelievable for the combo and the rpm's stay close to stock until throttle goes considerably more than that. On top of that, the engine is now quieter than the 2 stock ones I've had (drivetrain wise. lol)
And Brian, that cam you made me is absolutely EVIL! I am stunned at how much quieter the car is through the exhaust, even though nothing exhaust-wise was changed. I imagine it has to do with the more gradual valve events, but WOW! Talk about taking the sleeper effect to the next level!

Jake's Performance

iTrader: (2)

What kind of slip numbers does it show under these conditions?

In any certain gear or all gears?

mrvedit

I suggest hooking up a line pressure gauge to check if the pressure is sufficient to prevent slippage. As the trans and its fluid warm up, the line pressure goes down because the fluid is more viscous.
A local trans shop can easily do this, or buy one on ebay for $45.

prokilllsx

Sorry guys, I've been extremely busy with family and business and have not had time to get back here until now.
I believe it is doing it in every gear but it is most noticeable in 2nd. First gear is just over with so quickly and with that ratio, it pulls well enough to hide the symptoms in the second or so they would show. Second gear allows a couple of seconds to see and feel the problem. We finish the quarter mile in 3rd but since the car doesn't pull as hard in third gear, again it's harder to tell just how bad it is.
My last race was the second and last pass in the car since having the cam and valve train re-worked. The first pass was a waste due to poor track conditions and extreme tire spin. The second pass I torque-braked it up to about 2400 rpm and then launched at 1/3 to 1/2 pedal and then eased the pedal down once I realized the car dead-hooked. My 60 ft was a 1.68, 1/8th mile was 7.49 at 93 mph, and 1/4 mile was 11.70 at 116.8 mph. DA was 2500. Shift points were set at 6400 to avoiding being in the flat spot for too long. We should be able to spin to 7000 no problem if the problem was fixed. Even with the shift points set that low, I could tell it was there. My last race I was right next to my opponent all the way down the track. He literally ran an 11.68 to my 11.70 and he left a few thousandths of a second before I did. In all 3 gears it looked like this... I would put a bumper on him, then just before the shift he would make it up and put a bumper on me, my car would shift, then I would catch him then put a bumper on him, then, after 5800 rpm, he would pass me again, my car would shift and I was dead next to him, then he slightly inched me out as I got over 5800 again. We crossed the line just as my car fell off again.
Let's say it's a line pressure problem:
What are the possible problems and solutions?
Am I better off just to put the Performabuilt in instead of chasing the wrong thing?

prokilllsx

Ah, 2 more things to consider.
1. when I got the car it had a 5200 stall in it (for about 6000 miles maybe). I notice that on a 60 mph kickdown it just felt like crap. It made a lot of noise but just wasn't going anywhere until after it would shift to 3rd. Even then it didn't feel quite right. Now it has a 4000 stall and it's much better but still doesn't have that positive engagement feel.
2. I noticed a few days ago...took off from light, stepped it to half throttle, then it hit 2nd gear. chirped the tires but I felt what can only be described as a grunt. Took off from the next light, when nearly full pedal, hit 2nd gear. Quick shift but didn't chirp the tires and didn't feel that solid.
Does that add up?

Jake's Performance

iTrader: (2)

You could be losing pressure at high rpm. It's a possibility with a 4L60E due to the variable volume pump and not uncommon. The guys who really know how to make one live, know how to fix this.

prokilllsx

If there is much of a possibily that the clutches are burnt and it needs torn down, rebuilt, and modified; does it not make more sense to just swap it out for a well-built trans from a reputable dealer?
What I don't want to do is keep chasing this problem.

mrvedit

Yes, I think that is a good choice. Even mechanics that have rebuilt a thousand stock 4L60E won't know the various mods to the input drum to improve high rpm longevity. (In addition to the high rpm pump mod.)

prokilllsx

The last time I drove it I noticed that under light accelleration the 2-3 shift seems to have 2 stages. It's not a solid, single thump like the 1-2 shift.

mrvedit

That sounds like a "flare" where the 2nd gear band is fully released before the 3/4 clutch is engaged. Or it could just be the 3/4 clutch taking a long time to fully engage, in the process slipping and destroying itself.

prokilllsx

Thanks man, that makes sense. Time for a Performabuilt.