TH400 speedo question
You need a reluctor wheel from your old 4L60E (it's on the output shaft and needs to be pressed off). Machine the INSIDE of it to fit on the output shaft of the TH400 (don't remember the exact size but it must fit tight like it did when it was on the 4L60E shaft). Next you need to purchase an ELECTRONIC speed sensor for a TH400 (this can be purchased at a chevy dealer and was used in some trucks). The final piece is a pigtail with the proper plug end to plug into the new speed sensor (just cut off the factory speed sensor plug on you vehicle's harness and attatch the new plug to the original wires there is no polarity). Your speedo will now work and there is no tunning required as it's using the factory reluctor wheel from the 4L60E.
Yeah but you lose your ABS if you do that, not what everyone wants right?
In the TH400 FAQ there are two part numbers that you have to order from either LS1speed.com or GM directly and you'll be able to get your factory speedo working again.
GM8655291 GM Speedometer Sensor $99.99
GM8655315 GM Speedometer Drive Sensor Rotor $65.99
There you go
Searching this site is hit or miss so lets just try to help answer questions.
In the TH400 FAQ there are two part numbers that you have to order from either LS1speed.com or GM directly and you'll be able to get your factory speedo working again.
GM8655291 GM Speedometer Sensor $99.99
GM8655315 GM Speedometer Drive Sensor Rotor $65.99
There you go
Searching this site is hit or miss so lets just try to help answer questions.
Machine the INSIDE of it to fit on the output shaft of the TH400
I guess you need to figure out if you have the short 32 spline output or the small diameter long output.
TH400's came from the factory with electric senders on both sizes.
Last edited by 8a8mfh; Jul 29, 2007 at 06:41 AM.
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Originally Posted by XpEdItIoUs
Anyone know what is need to press it on?
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Originally Posted by XpEdItIoUs
Anyone know what is need to press it on?
Originally Posted by frcefed98
Pics of these pieces too please.
I have what look to be a set of speedo gears pressed onto the output of my TH400?
I have what look to be a set of speedo gears pressed onto the output of my TH400?
Originally Posted by GMRACER13
I put them on by heating them up first in a toaster oven. If you get it hot enough you should be able to slide it on by hand (wearing thick gloves). Have a punch and a hammer ready just in case it needs some adjustment before it has a chance to cool. If your too slow and it cools down before you get it EXACTLY where you want it and it won't move you can re-heat it with a torch.
Thanks for that info GMRACER13. I'll check em out a lil closer. When I say a set..there are two sets of helical gears one in front of the other. I took the tailshaft housing off to see what was on the output shaft and thats what was there
LOL what a pain this has been.
J
LOL what a pain this has been.
J
Originally Posted by frcefed98
Thanks for that info GMRACER13. I'll check em out a lil closer. When I say a set..there are two sets of helical gears one in front of the other. I took the tailshaft housing off to see what was on the output shaft and thats what was there
LOL what a pain this has been.
J
LOL what a pain this has been.
J
A lot of them had a STEEL SPEEDO GEAR.
The easiest way to get these off is with a cutoff wheel.
The gear you see cut into the shaft up by the case is to drive the governor.
Both are steel gears
Cut off the first gear only right? 
Staging Lane
Joined: Oct 2006
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One of the gears is for governor drive, the other is speedo.
The governor drive is cut into the shaft.
Measure the depth of the speedometer gear from the end of the output shaft before removal and install the new one that same depth.
The governor drive is cut into the shaft.
Measure the depth of the speedometer gear from the end of the output shaft before removal and install the new one that same depth.