resonance question / tranny question
Thread Starter
Race Director
Joined: Nov 2000
Posts: 17,103
Likes: 39
From: stop the fun suckers
resonance question / tranny question
Resonance: If you experiance bad resonance could you please describe the driving conditions where it occurs?
My Setup:
1993 A4 LT1 Stroker (mild)
Rebuilt tranny 2800 stall vig converter
2.59 gears
After the stroker rebuild my converters went south so i just cut them off (cheaper than replacing). The car got louder but not to bad.. the rest of the exhaust is stock. At that time the tranny did not lockup (junky shop did a bad rebuild) and it eventually blew the 3-4 clutch pack.
Rebuilt the trans with the help of some tranny guys that are friends of mine (and own a tranny shop of good reputation in town), Pete K's help in selected parts and answering some 700R4 corvette specfic questions and the guys at Presicion industries.
Anyhow with the new tranny installed, when it locks up in OD below say 65 mph it seems like the exhaust is resonating (car vibrates alot). once i'm over 65 all is cool.. If i get in the gas enough a lower speeds to get the converter to unlock it also smooths out.. and in the same RPM in OD at teh same speed (under 65) without the converter locking up it does not resonate.
I took a few tranny guys for rides in it and they seem to thjink its the exhaust resonating with the car at low RPM's heavy load with the converter locked up.. however, someone elses thread got me thinking maybe something is goofed in the tranny...
Could you guys with exhausts that "resonate badly" describe what you car does in low RPM, heavy load lockup conditions...
Pete K - Any thoughts? think I screwed something up?
My Setup:
1993 A4 LT1 Stroker (mild)
Rebuilt tranny 2800 stall vig converter
2.59 gears
After the stroker rebuild my converters went south so i just cut them off (cheaper than replacing). The car got louder but not to bad.. the rest of the exhaust is stock. At that time the tranny did not lockup (junky shop did a bad rebuild) and it eventually blew the 3-4 clutch pack.
Rebuilt the trans with the help of some tranny guys that are friends of mine (and own a tranny shop of good reputation in town), Pete K's help in selected parts and answering some 700R4 corvette specfic questions and the guys at Presicion industries.
Anyhow with the new tranny installed, when it locks up in OD below say 65 mph it seems like the exhaust is resonating (car vibrates alot). once i'm over 65 all is cool.. If i get in the gas enough a lower speeds to get the converter to unlock it also smooths out.. and in the same RPM in OD at teh same speed (under 65) without the converter locking up it does not resonate.
I took a few tranny guys for rides in it and they seem to thjink its the exhaust resonating with the car at low RPM's heavy load with the converter locked up.. however, someone elses thread got me thinking maybe something is goofed in the tranny...
Could you guys with exhausts that "resonate badly" describe what you car does in low RPM, heavy load lockup conditions...
Pete K - Any thoughts? think I screwed something up?
Last edited by Z06_BluByU; Sep 21, 2006 at 10:59 PM.
Team Owner
Joined: Aug 2000
Posts: 40,156
Likes: 45
From: San Pedro CA
I would not bet against the exhaust. I had a problem with my corsa system - the main center muffler/resonator came apart, and the resonance was killer. Seriously deafening.
The C4 exhaust is prone to resonance as it is, removing the cats will only make it worse.
I would wait for Pete K to comment...
The C4 exhaust is prone to resonance as it is, removing the cats will only make it worse.
I would wait for Pete K to comment...
Safety Car
Joined: Apr 2003
Posts: 3,793
Likes: 9
From: VA
The LT1s have a natural resonance at ~1800-1900 rpm. Never heard of it making the car vibrate though. I think you have a tranny problem.
The exhaust resonance is better at heavy load, because you run right through that rpm range. It's low-load cruising at that rpm that sucks.
The exhaust resonance is better at heavy load, because you run right through that rpm range. It's low-load cruising at that rpm that sucks.
Thread Starter
Race Director
Joined: Nov 2000
Posts: 17,103
Likes: 39
From: stop the fun suckers
Originally Posted by Vis Croceus
The exhaust resonance is better at heavy load, because you run right through that rpm range. It's low-load cruising at that rpm that sucks.
thats the zone... low speed cruising, in OD - 1200-1600rpm
