95z115

I have a 1995 Z28 automatic transmission. When i floor my car, instead of shifting right before redline like it usually does, it stops a little short and the valves float and i get a loud ugly sounds from my exhaust and it wont shift into the gear. When i drive regular it is fine, even if i get on it, its fine, as long as its not floored. What is my problem? Thanks

treyZ28

are u sure your trans isn't slipping?

95z115

No I am not sure that the tranny is not to blame, but me and my dad both agreed we felt the sound was coming from the exhaust, I have a cutout so its pretty loud. I thought it was the tranny at first though, is there a way to test it to distinguish? It really sounds like the valves are floating though.

TobyZ28

Mine has just started to do this once in a blue moon.. I just had my tranny rebuilt so I think its the valvesprings. I also have a 95Z with a good bit of milage on it. I'll be replacing the valvesprings any time now...

94F1Z28

It does sound like it could be floating the vavles.I would change them out and then see if that fixes the problem and if it doesn't fix the problem then it is probably the tranny.And it never hurts to have a good set of valve springs so you won't really be wasteing any money.

95z115

Thanks 94f1z28, I will look into that. Also, another update, it also does it when i rev in nutral, when it hits 5,000 rpms it makes that grinding type noise in nutral, but i think if i wanted to i could keep revving higher. The noise seems to be coming from the engine bay (I want to say on the drivers side. Still think its the valve springs?

Ace_437

Don't rev it that high in nuetral. It's extemely hard on the motor as there is no load being placed on it. Maybe that's the cause of your valve float.

craigffb

I don't think it your valves floating, I think it's your trans. I had valve float and the car shifted fine, it just tapped before the shifts and it only did it at the track. If your valves are floating it because your springs are week. But like I said I think it's your trans.

bad95z28

i'd say check your coil wire and opti, etc. this sounds like something ignition related being that its high rpm.

Perry93TransAm

I think you may have both going bad, your floating because of the RPM but youre not shifting because the tranny may be slipping. Look your fluid over and see what it looks like if its burnt its obvious, if its been a while since you changed the tranny fluid , do that and look at the amount of clutch debris in the pan.
You can get an on head sping pressure checker to see if the spring pressure is ok.

Gripenfelter

Upgrade to LT4 valve springs from www.paceparts.com

95z115

So check the valve springs, tranny, and ignition? How will I be able to test these and see if they are at fault, I would first like to find whats wrong instead of like replacing the valve springs and ignition and then find out its the tranny and realize i just wasted money you know?

craigffb

If you do end up getting LT4 springs get them from Jason Cromer not pace. They are cheaper from Jason. That were I got mine and checked all the prices.

Perry93TransAm

You can check the valvesprings by either removing them and getting a spring scales (compress in a vice to max lift and to installed height) or get an on the head spring scales, it is a lever type compressor with a scales. Look your fluid over for tranny condition and debris in pan.

BennyBoy

Another vote for checking the ignition. My upper RPM range was really erratic when I got the car and changing the plugs did the trick.

Tranny went out a year later too though... lol.