Programming a T43 to work in an offroad buggy with 39" tires

[gmh308]

I'm the original poster's co-driver. I figured I would post a couple pics to help stimulate the discussion. I know Dave is out of town on business and will be more active on the thread here shortly when he is back working the buggy i think tomorrow.

yes those tires are rather talll!

I get different numbers to Swingtan. Dont know why: calculator says >

H0101 - 52750 per km / 84892 per mile
H0102 - 36 of course is same
H0103 - 4.56 of course is same
H0104 - 321 tire revs per km / 517 tire revs per mile.

These numbers if duplicated in the ECM should give you a 4000ppm speedo output signal. (OS & cal permitting.)

I doubled check the above numbers via regular math and they line up ok.

[swingtan]

The big problem is that you can't "guess" the circumference of these tires due to the size and probably running pressures. During racing, they will probably be inflated to a lower pressure than a normal car would to allow the tire to deform and add traction ( like drag slicks ) so the actual rolling circumference will be less once load is placed on them.

I should test the relationship between {H0101} and {H0104} to see if the individual numbers are critical, or if the relationship between them is what counts. I don't have an auto to play with ATM though. My figures were really just an example.....

To get the "real" rolling circumference, mark the tire with liquid soap or grease ( or anything that leaves a mark ) and roll the buggy forward so you get 2 marks on the ground. Then measure the distance.

Simon

[A6sportsracer]

I suggest setting it up for tap up/down shifting like the corvette, You may be able to install a vette wheel or column to use the tap up/down switches, if you use your own switch(s) you will need to wire it through an original corvette switch because of the three resistors in the switch.

[whypave]

Sorry I didn't post back up sooner. Our race was last Friday so last week was a lot of long days and nights getting the buggy put together enough to race.

On Tuesday of last week I took the buggy to Chuck at Corvettes of Westchester and we did some tuning of the T43 in my 6l80. it shifts much better now and actually downshifts which was a huge improvement in the race. the shifts are fairly slow and we need some more tweaking but we are working on it. the big improvement came from both setting up the right r&p ratio as well as tire size but then Chuck changed a bunch of other shift points and turned of torque management etc.

I will try to keep this thread updated as to my progress in case anyone is interested or someone comes along in the future trying to put one of these trans into a non GM can bus vehicle.

I must say now that I've learned to use EFI live a bit more its pretty damn cool to work with. the main problem i had originally is that the obd2 port on my Mast harness is not currently communicating with the trans. Chuck had to use a bench harness with an e38 hooked to it to get efi live to see the T43 controller. so we had to do a bit of extra work each tune to unplug the harness from the car to the trans and plug in the bench setup then reverse the process to go testing.

Unfortunately my 427 L92 has enoug power it snapped an axle shaft from street driving and the rear spool. we found that out the hardway when we went to qualify for start position last Thursday.

[Chuck CoW]

CHUCK CoW can tune ANYTHING with an A6!!!

WATCH and SEE BELOW!


Chuck CoW

[whypave]

Thanks for posting the video Chuck. once I get a few bugs sorted out with the buggy I want to come back and try and setup tap shifting. I need to get my obdII port live so we can talk to the transmission without your bench programming box.