4l80e question

[aaronr]

o.k. here my question. you should be able to divided your Tos by your TIS to get your gear ratio.
1st gear tis 2003/ tos 812 = 2.4667 so close but i guess it good.
2nd gear tis 3054/tos 2069 = 1.4760 so second gear looks good.
3rd gear tis 3106/tos 3114= 0.9974 So the gears are close but little off.
o.d. grear. tis 2682/ tos 2678 = 1.001 should this be .750
I can see the rpm drop when the truck goes in O.D.
4l80e has been rebuilt, racing clutches and shift kit.
Here is my log file. what do you guys think?

[joecar]

Hi aaronr,

I was looking thru various threads today and I must have previously missed this one by a few months, I do apologize...

The answer is this:

In the 4L80E, the TIS sensor reads the reluctor teeth that are machined on the circumference of the forward clutch housing.

The forward clutch housing is driven by the overdrive gearset.

In gears 1, 2, 3, the overdrive gearset drives the forward clutch housing at 1:1 ratio.

In gear 4, the overdrive gearset overdrives the forward clutch housing at 0.75:1 ratio.

The TIS sensor reads the RPM's of the forward clutch housing.

If you pick a place your the log chart where the TCC is locked, you will see TCCSLIP is zero,
and here you can divide engine RPM by TOS and you will find it to be 0.75.

:)

[aaronr]

Hi aaronr,

I was looking thru various threads today and I must have previously missed this one by a few months, I do apologize...

The answer is this:

In the 4L80E, the TIS sensor reads the reluctor teeth that are machined on the circumference of the forward clutch housing.

The forward clutch housing is driven by the overdrive gearset.

In gears 1, 2, 3, the overdrive gearset drives the forward clutch housing at 1:1 ratio.

In gear 4, the overdrive gearset overdrives the forward clutch housing at 0.75:1 ratio.

The TIS sensor reads the RPM's of the forward clutch housing.

If you pick a place your the log chart where the TCC is locked, you will see TCCSLIP is zero,
and here you can divide engine RPM by TOS and you will find it to be 0.75.

:)

Yea, i had my trans guy look at my log files as well and he said the same thing. Thanks for reply back :grin:.