Pulling my hair out

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yellow rose said:
It’s possible when it unloads the tires it’s getting enough RPM to make it hit the chip. If it is hitting the chip my deaf ears can’t hear it.

I know the Rev limiter works like it should. After I did the video I checked it at several other RPM and it was spot on.
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I could go w/ that ^^^^^^^^
 
bob mCcarty said:
I could go w/ that ^^^^^^^^
Click to expand...


It’s also possible I can’t hear the miss. I even put my ear buds in so I had no outside noise and I couldn’t hear a miss. My wife says I’m legally deaf and we all no she is never wrong so therefore, I must be deaf.
 
I set the high side limiter to its max of 10900, and it still had the issue. Tried the two step from 3000 to 4000. Launched from an idle without using the transbrake, and it did the same thing but just once. I’ve had the problem of it porpoising the rear suspension before, and this isn’t it. When it does that it will rev way up, and now falling on its face. When I’ve had that problem I can fix it by tightening the shocks a click or two.
I removed my front shocks, and can’t feel any abnormalities working them in and out by hand. Doesn’t mean they aren’t bad, but not glaringly so.
I really think this ties into the problem I had last year with it triggering the shift box to hit second at the release of the transbrake button. Never could figure that out, so I’ve had to shift by hand. Seems like something in the box is reading actual engine rpm wrong which would trigger the shift box, and now activating the limiter.
 
When you say you tightened up the shock 2 clicks, what did it change? As in did it make it stiffer in bump and rebound or did it make it stiffer in one direction and looser in the other. If I could understand what change happens when you move the clicker it would be easier for my simple mind to understand.

I know Calvert says it changes both when you turn the knob but I don’t know if it’s making both directions stiffer at the same rate or what exactly happens.

My cousin bought a set of Calverts for his flaming chicken (Firebird) and he claimed he had wheel hop with a set of Caltracs.

So I had his girlfriend take some close up video of it and what was happening wasn't “wheel hop” but the tire bouncing back after the hit. He got some of it out but not all of it. Calvert told him to buy a different tire.

The tire gets hit like you are hitting it with a big hammer. The harder you hit the tire, or if you use a bigger hammer or both, the more the tire will try to push the hammer back off the tire. That’s the same thing that happens in the car. The tire is fighting back. I’m not saying that’s exactly what’s happening. Now you have another box to test to rule that part out.

This kind of thing can drive you nuts, especially when you have to go to the track to make the car do what it’s doing. That gets expensive real quick. And frustrating.

BTW, you can get to the point where the valving of the shock can’t handle the shaft speeds it’s seeing. The only fix for that is to revalve the shock or buy a different shock.

Interestingly, Dave Morgan of the “Doorslammers” chassis book either wrote an article about shock speeds, or I heard it at one of his seminars or both.

Anyway, he was tuning on a big block Camaro with a stick and ladder bars. A horrible combination to say the least. Anyway, they had a data logger on the car so they hooked a potentiometer up to the rear shocks to measure how fast the shock was coming apart at the hit. With the shock on the stiffest rebound setting, the shock came apart so fast the computer showed the shock was essentially not controlling anything.

Like I said, that is a worst case scenario but I can be rather easy to overcome a shock’s ability to dampen in either direction. And that is the shock’s job. It has to control the motion of the rear axle. The instant center sets the maximum speed the tire gets hit and the shock needs to dampen that movement so you have some ability to tune the hit, and any motion of the tire/axle trying to bounce back into the wheel well.

I’m not saying that’s your issue. Just pointing out how important the shock is. As the engine makes more power and with a short, high IC like a Caltrac or similar system that hit can be incredible and the tire just can’t deal with it.

That’s why Pro Stock has a rule that sets the MINIMUM weight for the rear axle. If the PS guys had their way, they would put more static weight on the front suspension so they could hit the tire harder with the 4 link. There is more to it than that, but that’s the simple explanation as to why that rule exists. It’s also one reason you don’t hear the PS teams screaming for aluminum blocks. They don’t want to give up that forward weight.
 
I also forgot to mention that if you ever want to upgrade your distributor to a cap what has the HEI ends on it rather than the female sockets you now have, you can order a Mallory 208m. That is a nice cap with HEI ends on it and a nice wire hold down too. It comes with the kit to convert your distributor from that cheesy clip system that holds the cap down to housing. That’s a much better way to mount the cap, plus you eliminate the female socket ends on the cap.

Just an FYI and Summit says they have more than 10 in stock.
 
yellow rose said:
When you say you tightened up the shock 2 clicks, what did it change? As in did it make it stiffer in bump and rebound or did it make it stiffer in one direction and looser in the other. If I could understand what change happens when you move the clicker it would be easier for my simple mind to understand.

I know Calvert says it changes both when you turn the knob but I don’t know if it’s making both directions stiffer at the same rate or what exactly happens.

My cousin bought a set of Calverts for his flaming chicken (Firebird) and he claimed he had wheel hop with a set of Caltracs.

So I had his girlfriend take some close up video of it and what was happening wasn't “wheel hop” but the tire bouncing back after the hit. He got some of it out but not all of it. Calvert told him to buy a different tire.

The tire gets hit like you are hitting it with a big hammer. The harder you hit the tire, or if you use a bigger hammer or both, the more the tire will try to push the hammer back off the tire. That’s the same thing that happens in the car. The tire is fighting back. I’m not saying that’s exactly what’s happening. Now you have another box to test to rule that part out.

This kind of thing can drive you nuts, especially when you have to go to the track to make the car do what it’s doing. That gets expensive real quick. And frustrating.

BTW, you can get to the point where the valving of the shock can’t handle the shaft speeds it’s seeing. The only fix for that is to revalve the shock or buy a different shock.

Interestingly, Dave Morgan of the “Doorslammers” chassis book either wrote an article about shock speeds, or I heard it at one of his seminars or both.

Anyway, he was tuning on a big block Camaro with a stick and ladder bars. A horrible combination to say the least. Anyway, they had a data logger on the car so they hooked a potentiometer up to the rear shocks to measure how fast the shock was coming apart at the hit. With the shock on the stiffest rebound setting, the shock came apart so fast the computer showed the shock was essentially not controlling anything.

Like I said, that is a worst case scenario but I can be rather easy to overcome a shock’s ability to dampen in either direction. And that is the shock’s job. It has to control the motion of the rear axle. The instant center sets the maximum speed the tire gets hit and the shock needs to dampen that movement so you have some ability to tune the hit, and any motion of the tire/axle trying to bounce back into the wheel well.

I’m not saying that’s your issue. Just pointing out how important the shock is. As the engine makes more power and with a short, high IC like a Caltrac or similar system that hit can be incredible and the tire just can’t deal with it.

That’s why Pro Stock has a rule that sets the MINIMUM weight for the rear axle. If the PS guys had their way, they would put more static weight on the front suspension so they could hit the tire harder with the 4 link. There is more to it than that, but that’s the simple explanation as to why that rule exists. It’s also one reason you don’t hear the PS teams screaming for aluminum blocks. They don’t want to give up that forward weight.
Click to expand...
It tends to tighten the extension of the shock. The higher I go the less it drives the tire down at the hit. If it’s set low at 5 it will drive the wheel into the asphalt which causes the tire to bounce back which then bounces the whole rear end of the car. The axle doesn’t really move down much in the video where the shock is set at 9.
 
gumper said:
It tends to tighten the extension of the shock. The higher I go the less it drives the tire down at the hit. If it’s set low at 5 it will drive the wheel into the asphalt which causes the tire to bounce back which then bounces the whole rear end of the car. The axle doesn’t really move down much in the video where the shock is set at 9.
Click to expand...
What rear spring are you using?
 
It really seems g-force related . I have no idea how your injection system and fuel supply work but is there any possiblilty it is uncovering the pickup or cutting the fuel supply during extreme G's ?

On a side note.... do you happen to remember a Green 70 Hemi Charger 4sp car in Anaconda ?
 
gumper said:
I set the high side limiter to its max of 10900, and it still had the issue. Tried the two step from 3000 to 4000. Launched from an idle without using the transbrake, and it did the same thing but just once. I’ve had the problem of it porpoising the rear suspension before, and this isn’t it. When it does that it will rev way up, and now falling on its face. When I’ve had that problem I can fix it by tightening the shocks a click or two.
I removed my front shocks, and can’t feel any abnormalities working them in and out by hand. Doesn’t mean they aren’t bad, but not glaringly so.
I really think this ties into the problem I had last year with it triggering the shift box to hit second at the release of the transbrake button. Never could figure that out, so I’ve had to shift by hand. Seems like something in the box is reading actual engine rpm wrong which would trigger the shift box, and now activating the limiter.
Click to expand...
I wonder if it is an internal connection inside the box, affected by launch g-forces. You have had problems with the box that you still havent solved.
I would beg,borrow, or steal another box, (hopefully a known good one from a buddy) and try that.
It sounds to me like an ignition problem, not fuel or suspension. My half-fast opinion only.
 
33IMP said:
I wonder if it is an internal connection inside the box, affected by launch g-forces. You have had problems with the box that you still havent solved.
I would beg,borrow, or steal another box, (hopefully a known good one from a buddy) and try that.
It sounds to me like an ignition problem, not fuel or suspension. My half-fast opinion only.
Click to expand...
Yellow rose was generous enough to send me one to test. I also feel like that’s the problem as I’ve yet to find something else while going through everything else in the car.
 
Since it didn't hesitate in the burnout box, I'm guessing it isn't fuel...although it is bucking like my old truck did once when the fuel filter was clogged solid, so it might be worth a quick look. After watching it over and over I would agree that it appears to be some type of g-force related electrical issue. Best way to sort it out would be remove all the fancy bracket racing electronics and start minimal and add 1 piece back in at a time (this would mean completely unhooking power to the T-brake, shift box, etc). Best of luck.

Starting with the ignition box from YR is a good place to begin.
 
flyfish said:
Since it didn't hesitate in the burnout box, I'm guessing it isn't fuel...although it is bucking like my old truck did once when the fuel filter was clogged solid, so it might be worth a quick look. After watching it over and over I would agree that it appears to be some type of g-force related electrical issue. Best way to sort it out would be remove all the fancy bracket racing electronics and start minimal and add 1 piece back in at a time (this would mean completely unhooking power to the T-brake, shift box, etc). Best of luck.

Starting with the ignition box from YR is a good place to begin.
Click to expand...
I tried it with the shift box unhooked. I have the transbrake hooked to a toggle switch that was off when I tried foot braking. Can’t totally unwire the brake since that’s also how the car goes in reverse. Unwired the tach for one pass. I do have a little auxiliary shift light that I didn’t think to unhook, but it will be for the next run it makes.
 
Could it be the trans brake solenoid bouncing the plunger against the seat?
 
33IMP said:
I wonder if it is an internal connection inside the box, affected by launch g-forces. You have had problems with the box that you still havent solved.
I would beg,borrow, or steal another box, (hopefully a known good one from a buddy) and try that.
It sounds to me like an ignition problem, not fuel or suspension. My half-fast opinion only.
Click to expand...


I sent him one of my boxes that is the exact same as he has. And I’m sending out the box he has that doesn’t work today to be repaired. So he will have a different box to test with and all his wiring and such will all hook up without changing anything.
 
If your disconnect switch is older than 5 years, it's time to replace it. It's a maintenance item that is often overlooked and should be replaced every 3-5 years. I've had a lot guys with issues with Optimas as well, even mounted in the correct orientation. Dataloggers will tell you really quick the whole story, but since you don't have one the light bulb wired in the supply to your MSD box trick will work as long as the power cycle is long enough to flicker the light. Electronics don't like fast power cycles and may be the reason the shift box went to lunch in the first place.
 
I would swap out the ignition box, no matter how it tested on a bench.. have had several Digital 6 issues over the years that were bizarre
 
I gave you a very simple procedure in post #50 to check for electrical failure, if that is what the problem is. You have to start somewhere if you are going to fix the problem.

You could use two buzzers or two lamps if you wish.
 
I'm not a toilet guy but I do run methanol. You may be way lean when the car leaves. I know my carb stuff must be on the rich side at the hit other wise it stumbles. I had one just die at the hit, after richening it up it ran good.
 
Bewy said:
I gave you a very simple procedure in post #50 to check for electrical failure, if that is what the problem is. You have to start somewhere if you are going to fix the problem.

You could use two buzzers or two lamps if you wish.
Click to expand...
I don’t have a race for a few weeks. I can’t try it for a bit, but I will.

DavidDean said:
I'm not a toilet guy but I do run methanol. You may be way lean when the car leaves. I know my carb stuff must be on the rich side at the hit other wise it stumbles. I had one just die at the hit, after richening it up it ran good.
Click to expand...
I had the same thought since it has happened before albeit only one stumble. I richened up the idle mixture, and used a smaller bypass pill. No changes either way.

So far I rewired the ignition, removed the ballast resistor, changed the battery, in the middle of changing ignition boxes, moved the starter in case the power post was arcing off a header tube, went through the fuel system barrel valve, checked and cleaned all the grounds, and changed the shift timer box.
 
gumper said:
I don’t have a race for a few weeks. I can’t try it for a bit, but I will.


I had the same thought since it has happened before albeit only one stumble. I richened up the idle mixture, and used a smaller bypass pill. No changes either way.

So far I rewired the ignition, removed the ballast resistor, changed the battery, in the middle of changing ignition boxes, moved the starter in case the power post was arcing off a header tube, went through the fuel system barrel valve, checked and cleaned all the grounds, and changed the shift timer box.
Click to expand...
When you removed the ballast resistor did you change out the coil?
 
gumper said:
I set the high side limiter to its max of 10900, and it still had the issue. Tried the two step from 3000 to 4000. Launched from an idle without using the transbrake, and it did the same thing but just once. I’ve had the problem of it porpoising the rear suspension before, and this isn’t it. When it does that it will rev way up, and now falling on its face. When I’ve had that problem I can fix it by tightening the shocks a click or two.
I removed my front shocks, and can’t feel any abnormalities working them in and out by hand. Doesn’t mean they aren’t bad, but not glaringly so.
I really think this ties into the problem I had last year with it triggering the shift box to hit second at the release of the transbrake button. Never could figure that out, so I’ve had to shift by hand. Seems like something in the box is reading actual engine rpm wrong which would trigger the shift box, and now activating the limiter.
Click to expand...
Pages.

Are the mounts tight, no trans or motor bucking?
 
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