Noise in drag car

July 28, 2025, 09:54 PM

markemark

Noise in drag car

quote:
I had torque converter bolts that were just a little bit too long. No clue how that happened. Had some noise whenever car was idling. don't remember noise while driving at any speed or any vibration, just a mild ticking. Broke two flexplates before noticing the bolts were tight, but not clamping down enough to the flexplate due to bottoming out in the torque converter. They tightened enough that it wasn't visibly apparent.

July 29, 2025, 06:31 AM

ski_dwn_it

Are the straps accounted for on your diaper? Last year I was doing an oil change and found some "hair like" fibers in my filter. Couldn't figure out what in the world they would have come from inside the engine. Started searching around and sorta wrote it off. While cleaning the car underneath I found the excess strapping from the belts that hold the diaper came loose and want up between the flywheel and motor. To my shock the strap got pulled into the motor thru the rear main seal! I tried to pull it out and it stopped after about 2inches of strap getting retrieved. Fear of pulling the main seal out, I cut the strap and ran the remainder of the season. 2 oil changes later no more strap signs in filter. On the off season I pulled the motor. about 3 inches remained inside. Never leaked a drop of oil.

The excess if there is any isnt blowing back and whipping the flywheel making a noise is it?

July 29, 2025, 09:26 AM

Goob

Have you looked into the valve train?
Broken valve spring?
Loose guide plate?
Loose tie bar on roller lifters?
Carbon knock?
Cracked or loose windage tray(s) or trap doors?

I heard a very distinct "ting" sound when I smacked an exhaust valve in the burnout once.

July 29, 2025, 10:05 AM

markemark

I use shaft rockers, check valves every 30 runs and keep records of last setting, record valves that need to be adjusted and by how much. Since new I’ve only had to adjust 10 valves 1 time, less than .002, and the other 6 have never needed adjustment. Spark plugs are 95 runs new that replaced a set with 268 runs. 7500 hi rpm limit and 7200 BO limit.

Car is always on the top of a 2 post lift when not racing.

Racing 3 days this coming weekend out of state and whether its making intermittent rattle or not I’m going to try driving it within reason.

July 29, 2025, 01:25 PM

Phil Dees

I had a pebble in a center cap make that noise before. I would only hear it at slow speed.

July 29, 2025, 03:16 PM

green1

Do you have slip on collectors and maybe have a tube rattling in the collector? I am deaf so I don’t hear these type of sounds but can imagine a loose tube bouncing in the collector will make a similar noise.

July 29, 2025, 04:21 PM

FootbrakeJim

Seeing a lot of worthwhile things to look at in the comments.
Markemark, I hope you have success this weekend, and figure out the cause of the noise.

Ski, we have all seen or heard of some wild stuff happening with race cars, but you win this week's prize for the most bizarre occurrence yet! You probably couldn't make that happen again if you tried!

quote:
Originally posted by ski_dwn_it:
Are the straps accounted for on your diaper? Last year I was doing an oil change and found some "hair like" fibers in my filter. While cleaning the car underneath I found the excess strapping from the belts that hold the diaper came loose and want up between the flywheel and motor. To my shock the strap got pulled into the motor thru the rear main seal! I tried to pull it out and it stopped after about 2inches of strap getting retrieved. Fear of pulling the main seal out, I cut the strap and ran the remainder of the season. On the off season I pulled the motor. about 3 inches remained inside.

July 29, 2025, 04:58 PM

markemark

quote:
Do you have slip on collectors and maybe have a tube rattling in the collector?

My collectors are welded to these mufflers that have a straight thru baffle. This baffle has come loose slightly in the past but the bend I put on the ends have made them tight. I always check them after a racing weekend.

The collectors slip onto the header tubes. Because I use an O2 sensor I want the tubes sealed tight and use hi temp silicone on the collector openings and sliding the tubes in seals extremely well. When one tries to pull them apart it takes a sincere effort. I then wrap the tubes to the collector with exhaust wrap and they remain tight not moving, no leaks. Been doing this for 5 years.

July 29, 2025, 05:08 PM

markemark

quote:
I had a pebble in a center cap make that noise before. I would only hear it at slow speed.

I removed the distributor cap recently checking the center ball and overall condition. There is some play in the rotor/ pump drive shaft and considering removing this to inspect the gear next.

July 29, 2025, 06:51 PM

green1

quote:
Originally posted by markemark:
quote:
Do you have slip on collectors and maybe have a tube rattling in the collector?

My collectors are welded to these mufflers that have a straight thru baffle. This baffle has come loose slightly in the past but the bend I put on the ends have made them tight. I always check them after a racing weekend.

The collectors slip onto the header tubes. Because I use an O2 sensor I want the tubes sealed tight and use hi temp silicone on the collector openings and sliding the tubes in seals extremely well. When one tries to pull them apart it takes a sincere effort. I then wrap the tubes to the collector with exhaust wrap and they remain tight not moving, no leaks. Been doing this for 5 years.
Well there goes that thought

July 29, 2025, 07:48 PM

inferno camaro

I had a rattle I chased half a season, ended up being the outside of the harmonic balancer was loose and spinning around the center portion.

July 29, 2025, 08:34 PM

markemark

quote:
Originally posted by inferno camaro:
I had a rattle I chased half a season, ended up being the outside of the harmonic balancer was loose and spinning around the center portion.

Interesting…. Were you able to rotate the outside shell by hand? If not did the balancer indicate the wrong timing even when it was correct when checked?

July 29, 2025, 09:19 PM

inferno camaro

I never found it until it was pulled to freshen it at the end of the season. Yes you could grab it and spin it by hand.

July 29, 2025, 09:57 PM

Canted Valve

quote:
...the outside of the harmonic balancer was loose and spinning around the center portion.

I have a C6 corvette, both C6 and C5 generations are famous for failing OEM harmonic dampers. Mine has survived thus far, but I have put paint index marks around the face through the hub, elastometer and the outer ring. Each time I'm in the area one of the marks is generally visible and I can confirm no movement... so far.

July 30, 2025, 08:48 AM

ski_dwn_it

quote:
Originally posted by FootbrakeJim:
Seeing a lot of worthwhile things to look at in the comments.
Markemark, I hope you have success this weekend, and figure out the cause of the noise.

Ski, we have all seen or heard of some wild stuff happening with race cars, but you win this week's prize for the most bizarre occurrence yet! You probably couldn't make that happen again if you tried!
quote:
Originally posted by ski_dwn_it:
Are the straps accounted for on your diaper? Last year I was doing an oil change and found some "hair like" fibers in my filter. While cleaning the car underneath I found the excess strapping from the belts that hold the diaper came loose and want up between the flywheel and motor. To my shock the strap got pulled into the motor thru the rear main seal! I tried to pull it out and it stopped after about 2inches of strap getting retrieved. Fear of pulling the main seal out, I cut the strap and ran the remainder of the season. On the off season I pulled the motor. about 3 inches remained inside.

Glad I won something

July 30, 2025, 11:18 AM

markemark

I just finished getting everything back together from the new flexplate install Monday. Of course it was raining out this morning, but it stopped for 15 minutes and I pushed the car out on the driveway and started. Could only drive it backwards and forwards for 150’, but doing this a dozen times and getting the trans to 125* the noise was GONE!!!

I want to Thank Everyone that offered suggestions and support as it was appreciated. Feel much better knowing I have a safe car to compete in this weekend. Mark

July 30, 2025, 12:06 PM

ski_dwn_it

Glad you got it. So you feeling it was the flexplate? Any signs of anything on the one you took out?

July 30, 2025, 12:50 PM

markemark

^^^I have a lighted magnifier on an articulating stand and looked at the old felxplate and there are no cracks that I can see and the welds on both sides on the ring gear look perfect. Somehow, it’s making noise. I’ll know for sure this weekend but am confident that this was the problem.

What is unusual is that I had a starter fail along with a stuck spool in the VB while trying to determine the noise problem.

I’m having a new full Reid th400 fresh build being assembled today, dynode tomorrow and picking up Monday. They gleaned the planet and VB from the old trans.

July 30, 2025, 01:03 PM

FootbrakeJim

Really glad to hear that you got it solved!
Now you will have one less "bug" working in the back of your mind as you are preparing for your next pass... Best of luck to you this weekend.