Bracket Talk
Grid RPM Shift issues

This topic can be found at:
https://drr.infopop.cc/eve/forums/a/tpc/f/80760912/m/3587065396

June 05, 2020, 09:36 PM
Bigdrive88
Grid RPM Shift issues
A friend of mine just installed grid igntion on his new dragster. The shift point is set to 7200 on & 7400 off. It is actually shifting around 7700. Approx 500 rpm more than its set to do. Any Ideas ?
June 06, 2020, 07:51 AM
Alaskaracer
What wire is he using to trigger the shift? Brown and white? I did that and had the same issue...markemark had me change to the yellow shift light wire and now it's pretty much spot on.


Mark Goulette
Owner/Driver of the Livin' The Dream Racing dragster
www.livinthedreamracing.com
"Speed kills but it's better than going slow!"
Authorized Amsoil Retailer
June 06, 2020, 08:06 AM
Bigdrive88
He is using the brw/white. When Mark help me set mine up he had me use the yellow wire as well.
June 06, 2020, 08:36 AM
Mike Rietow
I put a grid in my ride so I could shift to high 3 tenths after transbrake release and pull 14 degrees simultaneously, in order to slow down to as close to 6.50 as I could get, for a 370 pro tree 6.50 index class.

I made 4 runs within a couple thousandths, on the fifth in the quarter finals the shift was late and the car sped up a bunch 60 ft. Because the shift was late instead of holding a tenth, I was actually holding two tenths.

I only ran it for one race BUT I had heard prior to the race the shift isn't good with a grid, and I didn't have any reason to monkey with it to resolve the glitch, so I'd be interested to hear from Mark on this as well.



This message has been edited. Last edited by: Mike Rietow,
June 06, 2020, 09:53 AM
SCDIV1
Page 11 of the TIPS thread gives a ton of helpful information on the grid.

I’ll be reading this one myself. I just hooked up my grid after using chips previously with an analog box. Swapped to all grid.
June 06, 2020, 06:34 PM
markemark
Here’s the error one makes when first using the Brown / White wire for the Output Switch to shift with. The Output Switch is Not an accurate RPM output device. Output Switch is a “Timer” with an RPM function. The RPM function in Output Switch is best used to create a “Window “ of when the Timer function will output.

When forced to use the RPM feature in Output Switch for shifting (and several other things)it’s
Best to program in Hysteresis mode. This means the ON RPM value is set higher than the OFF RPM value. Example ON RPM = 7200 OFF RPM = 7100.

Shift Light Output (Yellow wire) is the most accurate RPM output in Grid. It also allows some other features to work with it to control the Gear Indicator in the event of peddling prior to shift. It’s best to use Shift Light for shifting your car. That’s what it’s designed to do.

Somehow (I blame the person that wires the car)the Output Switch gets wired to the shifter. How that person determines this I do not know. The only thing I recommend is to STOP doing this !!!
June 06, 2020, 07:29 PM
SCDIV1
I recently installed the grid black box removing a 7AL3 and this rpm shift activation wiring led me to use the brown and white wire in place of the RAS output on my old analog box. I will have to change it to the yellow.

The K&R color coded wiring diagrams show it wired this way if I recall right. Brown and white to RAS terminal on K&R panel. I’ll have to recheck that, it might be shown as the yellow

I have K&R relay/fuse and switch panel and delay box.

K&R panel has a switch for RPM or time shifting.

I shift by time usually regardless of what type racing I’m doing.

Delay box controls the shift by time.

Thanks for the clarification on the rpm shifting issue with the grid.

It’s not real clear even reading thru the info you posted in the Tips thread that I have read.

This message has been edited. Last edited by: SCDIV1,
June 07, 2020, 08:28 AM
SCDIV1
Fixed it and tested it using the built in test feature. Shifter works in RPM mode.

The K&R drawing shows a yellow wire connected to the ras terminal on the relay panel. It originates at the grids brown and white and the yellow is blank. That is not clear and is maybe why some people like myself connected the brown and white thinking it was a mistake on the diagram.
June 07, 2020, 08:44 PM
369dragster
quote:
Originally posted by markemark:
Somehow (I blame the person that wires the car)the Output Switch gets wired to the shifter. How that person determines this I do not know. The only thing I recommend is to STOP doing this !!!


I’m not sure how you blame the person that wires the car when every set of directions that I have ever seen says to use the brown and white wire. If you can’t tell I wire cars. Haha


Ken
June 08, 2020, 05:59 AM
SCDIV1
And not for nuthin but who the h-e-l-l has ever heard the word Hysteresis and has any idea what that means !! LOL

Not me that's for sure.....
June 08, 2020, 06:34 AM
Alaskaracer
I think that word refers to what you become when you try to figure it out!!!


Mark Goulette
Owner/Driver of the Livin' The Dream Racing dragster
www.livinthedreamracing.com
"Speed kills but it's better than going slow!"
Authorized Amsoil Retailer
June 08, 2020, 09:20 AM
Mike Rietow
So, Grid can only shift the car consistently using the rpm mode, is that where we're at so far in explanation?

This is shifting three tenths after transmission brake release.

Pulling fourteen degrees timing simultaneously.


June 08, 2020, 09:25 AM
Bigdrive88
I think he is meaning that the Shift light output is the only reliable way to shift on RPM through grid. All i know is mine is setup through the shift lite & if i want to shift on time I use the delay box timer.



quote:
Originally posted by Mike Rietow:
So, Grid can only shift the car consistently using the rpm mode, is that where we're at so far?

This is shifting three tenths after transmission brake release.


June 08, 2020, 09:31 AM
SCDIV1
For S/C racing and generally for bracket racing I usually shifted by time....

Very fast shift in S/C and the delay box controls the time shift....

I used short time shifts to try and stay above 7.50 ET's in decent air at Etown....

Don't have an Advanced ET license...7.50 an under

Car did not care how early I shifted and was in the 7.40's....

I just looked at an ET slip from one of those days and shifted at well under 1.5 seconds...

For S/C its almost immediately into high gear.....and I'm on the stop before that shift....
June 08, 2020, 10:01 AM
Mike Rietow
quote:
Originally posted by SCDIV1:
For S/C racing and generally for bracket racing I usually shifted by time....

Very fast shift in S/C and the delay box controls the time shift....

I used short time shifts to try and stay above 7.50 ET's in decent air at Etown....

Don't have an Advanced ET license...7.50 an under

Car did not care how early I shifted and was in the 7.40's....

I just looked at an ET slip from one of those days and shifted at well under 1.5 seconds...

For S/C its almost immediately into high gear.....and I'm on the stop before that shift....


I was slowing a 5.90 car down to 6.50, shifting three tenths after transmission brake release, pulling fourteen degrees timing simultaneously.

370 Pr Tree 6.50 index class.

This was as slow as I could get it to go.

The shift was inconsistent shifting on time using Grid.

No delay boxes allowed in the class, in order to accomplish the shift, three tenths after transmission brake release.

The shift was late on the fifth pass using the Grid in this fashion, speeding the 60 ft up seven hundredths.

This message has been edited. Last edited by: Mike Rietow,
June 08, 2020, 10:11 AM
markemark
quote:
Originally posted by 369dragster:
quote:
Originally posted by markemark:
Somehow (I blame the person that wires the car)the Output Switch gets wired to the shifter. How that person determines this I do not know. The only thing I recommend is to STOP doing this !!!


I’m not sure how you blame the person that wires the car when every set of directions that I have ever seen says to use the brown and white wire. If you can’t tell I wire cars. Haha


If you can, share with me the source of these instructions showing how Grid is best wired to your product.

I’ll try to post more information tonight about the Shift Light and Output Switch that will show why and how to best use these outputs.
June 08, 2020, 11:27 AM
SCDIV1
Markemark is the only poster I know that may be able to sort out this shifting by time using the grid issue.....

If you can't use a delay box to shift there must be a way to use the grid and have it shift accurately every pass.....

Use RPM along with the time window switch.....you jus need to figure out what the rpm needs to be and program it right.....I think ! LOL


OR maybe rig up a stand alone t-stop timer like a Dedenbaer TS-1 to shift on time from launch.....get creative....LOL

This message has been edited. Last edited by: SCDIV1,
June 08, 2020, 11:58 AM
TomR
Been using the brown and white wire since I first wired it.

Me settings:




The results:


I figured the 200 rpm delay was because I have the brown and white triggering a relay to power the Biondo electric shift solenoid.


72 Nova "Hooptie"
June 08, 2020, 07:03 PM
markemark
Here’s an example of how to properly program the Grid Output Switch to shift your power glide using the Time function. This car normally shifts at 1.75 seconds to achieve a 7000 rpm shift complete time. It has a Maximum RPM limit of 7800 programmed in the Grid REV Limiter tab.

In RPM Switch you create a RPM Window of when the Output Switch can be activated. In this example the window is 3000 rpm large and opens at 5000 rpm and extends to 8000 rpm which exceeds the 7800 rpm Maximum RPM limiter set in Grid.

In Time Switch the Activation point is programmed to 1.75 and the Duration is 0.35.

Here’s what happens. After the Launch input is enabled and released, the Time From Launch Timer (TFLT) starts to run. The engine achieves 5000 rpm shortly after launch and enables the RPM Switch programming. As long as the engine is between 5000 and 8000 rpm this with be enabled. The Timer is also running. When it achieves 1.75 seconds, and the rpm is greater than 5000 but less than 8000 it will activate the Output Switch, and it will turn ON for the programmed Duration of 0.35. Once the Duration has timed out the Output Switch will turn OFF and not restart again until the TFLT is reset to 0.00 and restarted.

You can watch the TFLT run by turning the ignition ON and cycling the Launch input ON / OFF. Cycle Launch input ON/ OFF again and it’ll reset TFLT to 0.00 and start again.

This is why you program the RPM Switch function when using Time to shift with. In the event you cycled the Launch input prior to leaving the start line (using reverse or bumping the switch), Output Switch would NOT turn ON because the RPM Switch will be off as the engine rpm is not between 5000 and 8000.

The Output Switch is a “TIMER” with an RPM function. This Output Switch Timer is accurate. By this I mean that it will closely repeat the same output time given the programmed time settings.


June 08, 2020, 07:41 PM
markemark
quote:
Originally posted by SCDIV1:
The K&R drawing shows a yellow wire connected to the ras terminal on the relay panel. It originates at the grids brown and white and the yellow is blank. That is not clear and is maybe why some people like myself connected the brown and white thinking it was a mistake on the diagram.


If K&R drawing (proprietary?) is showing that you land the Brown / White wire from Grid to the shifter input, then there are many installing this kit that have it wired this way (incorrectly IMO).

Ask the guy that has his high power electric shifter ON a second time just before the finish line because of this incorrect (less accurate) RPM shifting choice (Output Switch) in Grid.

You can use the (less accurate) RPM feature in Output Switch to shift with if you desire. But, it is wise to use the Timer function as a window of when it can activate on RPM to keep the Output Switch from turning on a second time prior to run completion.