Speed Calibrator on The Mark

Ordered 2 front tires - 235/45/18 Pirelli PZero Nero's for the front of The Mark today - on sale at Tire Rack $165 ea. :) . They are the closest size that I could find to match the circumference of the rear 265/40/18 MT ET Street drag radials.

Hopefully, this will help Aric tune the trans now that all the tires will be rolling at the same speed. :)


http://www.tirerack.com/tires/tires...5YR80NXL&vehicleSearch=false&fromCompare1=yes
 
OK Here is the final diagnosis on the mysterious shifting issue that has had Aric chasing it for some time now. He data logged the crap out of the car, and has concluded the tune is fine. He made some minor tweeks, but the problem actually lies with not being able to hook the tires.

He has in one log, where he launched the car with violent spin, that commanded shifting early, and when it finally hooks, it commands a downshift because of slower wheel speed - like it should. He kept the logger going and brought the car to a stop and launched it again, only this time, it hooked. Bam, bam, bam, and the car went through the gears perfect. He was able to duplicate this test a couple times, and is convinced the tune is doing what it was designed to do.

The new front tires that now matched the circumference of the rear drag radials, fixed the bouncing speedo needle, and the stock 327 speedo gear is back in the car.

I should pick up the car tomorrow or Saturday, whenever he has JC detail it for me.

Now the big test will be when I take the car to the track, whenever this daggum rain stays away for a weekend. :)


I finally had Ryan print off a copy of The Marks final dyno sheet, with the new T-Trim and 3.33 pulley. This is with the neutered street tune and big pulley that I asked them to do, to keep it way way safe. This is the tune that is in the car now. One of the nicest graphs I have seen with 0 smoothing. Aric is my hero... :)

DSC02435.jpg
 
Crud, I should have read your last post before sending that PM.

Although it sounds like you are saying the car spins its tires in the top of third and shifts to fourth then realizes it was too early and downshifts back to third? So its not the TC locking then unlocking?
 
During the testing Aric was doing, overdrive, traction control, and the WOT torque converter lock up function were all turned off. If the tires spun from a standing still start, it would shift 1-2-3-2-3 in a 1/4 mile run.

Aric turned the WOT torque converter lock up function back on now that he is convinced the tune is good, so now if the car hooks with no spin, it should be 1-2-3 and then torque converter lock up right after it goes into 3rd.
 
I took The Mark to opening day at Atlanta Dragway yesterday to see how the car will shift. Had some fun, and most importantly, I did not break anything :) I could not get the car to hook at all, and the car was shifting like it did not know what gear it needed to be in. Aric said it would do it if it did not hook, and he was right.

I made three passes - a 12.5, 12.4, and a 12.8. Turn the volume up on the video and you can hear the shifts. Wendy and I ended the day going to Sonny's for some BBQ, then to the outlet mall for some shopping.


Here is a link to Wendyvision...

Atlanta Dragway T&T 2-27-10 - Car Videos on StreetFire
 
Stangman said:
Anyone ever use the Dakota Digital speed calibrators from Summit?
Click to expand...

I have one lying around that I've been too lazy to install.. looks like a quality piece. Bought direct from Dakota Digital cheaper than Summit, looks like the price is the same now but you might save a couple $$ on shipping...
 
Just my two cents, I had the same type of problem. It was the difference in tire size, the Mark uses a differential traction control to control vehicle slide along with wheel spin, same as town cars and later model continentals. The ABS sensor calibration needs to be changed front to back to achieve the same ratio. Even with the traction control of, the ECM stills see's the different ratio front to back and will try to compensate by controlling the trans shifts and lock up.
P.S. The wheel sensors and ECM still are trying to control differential wheel slide, and spin as if the traction control is fully active. Front sensors show a lesser speed compounded by a difference tire size, traction control is not active but the ECM still reads the differential ratio settings and will pull lock up to apply ABS and up shift or down shift to manage torque. Net result strange full and part throttle trans behavior, playing with the lock up and shift modifiers will help but not cure.
 
I fixed the tire size issue. Ordered 2 front tires - 235/45/18. They are the closest size that I could find to match the circumference of the rear 265/40/18 MT ET Street drag radials. The fronts roll 789.6 revs per mile, and the rears roll 790.2 revs per mile. I still have 4 shifts and a tc lock-up when at the drag strip going down the track.

I had a 1.849 60' on the first pass, a 1.926 on the second, and a 2.002 on the third. 15psi in the dr's. This car has never done better than a 1.8 60', even with the 16" ET street tube tires on Marauder rims, or the 16" ET street dr's on stock rims.

All three passes, the car shifted 1-2-3-2-3-lock up, or 1-2-1-2-3-lock-up. lol Take your pick - I count that many shifts going down the track. From what I have been told the other day, this shift sequence will happen if I spin the tires. I assume the tires are spinning like hell, because of the 4 shifts. If the tires aren't spinning like hell, what else could it be? I suspect the tune, but I have been shown data logs that prove otherwise. :confused:
 
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