Looking for a better $8D

[RobertISaar]

CARS existed back into the 8D and possibly earlier days.... it's just control of a relay (IIRC) that's used to block all shifter positions except for 1st and 4th on the T56 and i think one other 6 speed manual.

[1project2many]

IIRC only last year of TPI Vette had 6 speed trans... 1991. CARS was called CAGS, Computer Aided Gear Selection. Prior to that GM used weak Doug Nash 4 speed OD transmission which was really a T10 with an overdrive planetary set on the back. Same wire and ecm controls used to operate planetary solenoid as TCC in auto trans. Neat idea but ultimately too weak for serious performance. And funny too, because similar idea 3 speed w/ overdrive manual used from '50s to mid '60s was also too weak for serious performance.

We used to have a international 4300 at work that had to ultrashift. It didnt know the first thing about shifting. It would upshift too soon, and wait way too long to downshift. It sucked.

They're pusing to use "progressive shifting" which is earlier shifts based on torque curve. Doesn't feel as fast and seems to lose power but numbers say otherwise time and again. Computers programmed this way can be pretty blind to what the real world needs are.

[RobertISaar]

looking through alldata diagrams.... 90 corvette L98 shows the 1-4 upshift relay.
89 shows it as well.
88 and earlier has some other type of relay, "overdrive relay", i don't think it serves the same purpose though.

so, i'd bet it's somewhere in the 6E code as well.

and i've always wondered: so use the clutch for shifting 1-4, but shifting 4-5 and 5-6 requires no clutch movement, right?

[JeepsAndGuns]

CARS existed back into the 8D and possibly earlier days.... it's just control of a relay (IIRC) that's used to block all shifter positions except for 1st and 4th on the T56 and i think one other 6 speed manual.

What the heck is the purpose of that?!?!?
If there was something as stupid as that on a vehicle I owned, it would quickly be disabled.

[EagleMark]

It's a communist plot against the American way...

[1project2many]

The purpose of CAGS / CARS was to improve CAFE compliance. Govt watches average fuel economy for a company's entire fleet of vehicles. Gas guzzlers like Cadillac and hi perf Camaro need to be offset by Aveo's and Metros to keep numbers in line or else big fines. CAGS caused gearshift to bypass 2nd gear position and drop into 4th. This improved economy in EPA mileage testing and helped CAFE.

looking through alldata diagrams.... 90 corvette L98 shows the 1-4 upshift relay.
89 shows it as well.
88 and earlier has some other type of relay, "overdrive relay", i don't think it serves the same purpose though.

Thanks for the clarification. Something has stuck in my mind about a 91 Vette with 6 speed though. Maybe it's just that that was the best TPI plus 6spd to own. Anyway, the overdrive relay is for the Doug Nash trans. http://www.5speeds.com/dne.htm Also called "4+3" as the OD unit could be engaged in 3 of the forward gears.

All shifting required clutch. CARS is attached to the shifter and affects the shift gates. Nothing is affected internally.

Mark, just because you're paranoid doesn't mean they're not out to get you. The best boy scouts know the value of being prepared.

[JeepsAndGuns]

Anyone have the error code listing for a $8D car? I'm thinking there are a couple in this XDF thats not actually used.

[JeepsAndGuns]

No one has a error code list? I would much rather trust a list from yall than a random list from the internet. I think there are a couple in the xdf that not correct, or not used. Also want to double check the other ones.
Right now thats the only thing holding me up.

[RobertISaar]

alldata list for 91 firebird w/5.7TPI:

13
14
15
21
22
23
24
25
32
33
34
41
42
43
44
45
46
51
52
53
54