TH350 and your factory speedo:
The TH350 transmission was designed to be used with a cable driven speedometer. There is a drive gear mounted on the tailshaft and a driven gear mounted in the tailshaft housing that drives the cable to the speedometer.

Your LS1 car uses a Vehicle Speed Sensor (VSS) and reluctor ring. The metal reluctor ring is mounted on the tailshaft and passes by the 2 magnets on the VSS sensor creating a pulse with every tooth. This VSS signal out of the transmission is an AC sine wave. The VSS signal has two sides, one grounded at the PCM (VSS LOW) and the other side (VSS High) the PCM takes the signal and modifies it into a square wave and outputs 4000 pulses per mile for use by the speedometer, odometer, cruise, radio and the PCM uses the signal to determine which block learn cells to use. Which is very important for a street driven application.

The ABS uses a Wheel Speed Sensor (WSS) and a reluctor ring to pulse the same AC sine wave to report wheel speed to the Electronic Brake Control Module (EBCM) as the VSS uses to report vehicle speed to the PCM. To make your speedometer work with the TH350 you can use one of your front Wheel Speed Sensors as your VSS signal.

The VSS reluctor ring on the tailshaft of the T56 has 17 teeth, thus makes 17 pulses per TAILSHAFT revolution, but pulses more than that per TIRE revolution because it goes through the ring and pinion. So multiply the gear ratio by the number of reluctor teeth. So a 3.42 gear ratio would pulse 58.14 times per TIRE revolution (3.42 x 17).

The VSS reluctor ring on the tailshaft of the 4L60E has 40 teeth, so multiply gear ratio times number of teeth. So 3.42 x 40=136.8 Pulses per TIRE revolution.

The number of teeth on both front WSS reluctor rings is how many pulses they give per tire revolution, because they are attached to the wheel. The number of teeth on the front WSS is less than 58.

T56 or 4L60E to TH350:
Just cut the two wires that run to your front WSS and splice the VSS wires into them. Wires are: Tan --> Yellow , Dkgrn -->Ppl (Right Front WSS).


THIS WILL DISABLE THE ABS. Your ABS will not work without one of its WSS sensors, but you will regain the use of your speedometer, odometer, and cruise

EDIT: You cannot just "splice" into WSS wires for the signal and have both ABS and a speedometer.

When using this mod your speedometer won't be exact. You can correct this easily with programming just like compensating for different gears/tire sizes. Use 2.76 for switching from a 6spd. Use 1.175 for switching from an A4. Be sure and check your roll out on your front tires to get it exact.

 

wow. this is an awesome write up. i have one question though. is there any way to leave your WSS connected but just splice in the VSS into the wires?

 

No, unfortunately not. The ABS will detect a weak/incomplete signal and become inoperative. The same condition that can be caused by a dirty sensor or metal on the WSS.

 

Why dont you just take the reluctor off a 700R and put it on a 350 and use a late model extenion housing thats alot simpler?

 

There isn't a tailhousing that is in equal length of the TH350 9" tailhousing that uses any type of VSS. The reason for the use of the 9" tail TH350 is to keep from purchasing a driveshaft. (M6 to TH350)

 

Good write up, when I get my car back from the auto body shop I will try this and hopefully report back good news. Thanks again!

 

Thanks alot guys, It works fine on my car but still need to calibrate the speedo. I jumpered some wires on top of the EBCM connector to shut off my abs inop and brake light. I then wired up my line lock so that when engaged it lights up the Brake light on the instrument panel.

 

for your info we make a custom reluctor ring for the 350 and 400 in m-6 and a-4 tooth count and have the sensors and tail housings for them also
so it is a bolt up deal

 

What would be the total price for what you would need for the TH350?

 

Do you need a n m-6 or a-4 kit as parts ar diff.

 

My car was originally a M6, but lets have the A4 price also.

 

reluctor ring is $18.00 for m-6 or a-4 the sensor for m-6 is $30.00
tail housing are $75.00
for the a-4 tail housing is $125.00 and the sensor is $80.00
total m-6 $123.00
total for a-4 $173.00
shipping on either is $18.00
we have a few of each left

 

Thanks alot Yank, Now we have another way to make the factory speedo work.

 

I have been told on a couple different ocasions that the TH400 with 9" tail shaft can use the M6 cross member and drive shaft. Can anyone confirm?

Also can the 6.0 or 98 flexplate be used on the TH400 TC without any other mods to it? Or do you still need to file the holes?

Finally (for now), what shifter works the best (least modification to console) in the M6 center console?

 

Yes, they both have the dual pattern. LS1 and SBC/BBC 10.75

 

So no spacers needed either then?

 

If I have a 9in tail housing already do I still need a new one or can I use the old one? M6 car...th350.

 

Ditto, I have a 9" TS, was an A4, converting to A3. But, I was told I need to convert to a M6 PCM Flash, so do I need a M6 or A4 setup, more confusing I know.

 

I think if you already have an A4 then you need the reluctor ring setup for the A4 so that it can be plug and play. Everything else will need to be setup for M6. (i.e. delete all electronic shifting codes from the PCM).

 

I originally thought the same, but wondered if the reluctor would need to be for an M6, with the whole tooth count being different for M6 vs. A4 (figure it must be in the tune, unless of course it resides in the VSS.