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Old 08-12-2017, 05:29 PM   #1
RedBed
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New 4L60 (YEA!) and speedo problems... :(

Just picked my truck up from the mechanic. He swapped my TH350 out for a 4L60. Works great and happy I did it. Hopefully the extra MPGs will help pay the bill.

About halfway home, the Speedo quit working. And I did speak to the mechanic and he will fix it later in the week, but I thought I'd ask about it first.

As I said - it worked, then didn't work. No noise, and the cable was recently lubed.

I unhooked it at the transmission side, spun the cable, and the speedo works. What would cause it to quit working inside the transmission?

When I removed the cable from the trans side, a very small wire ring (like a clip) fell out, so I have it in an envelope.

Any ideas? I might fix it myself if I can.

Also - He said it is currently 17/37 speedo gears. When my speedo reads 60, my GPS speed is 57. So would that mean I need to maybe a 17/36 setup?

THANKS
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Old 08-12-2017, 07:32 PM   #2
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Re: New 4L60 (YEA!) and speedo problems... :(

most likely stripped the plastic drive gear..

Last edited by mongocanfly; 08-12-2017 at 07:38 PM.
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Old 08-12-2017, 08:23 PM   #3
RedBed
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Re: New 4L60 (YEA!) and speedo problems... :(

Does the little clip have anything to do with holding the gear from moving back and forth?

I thought about the teeth being stripped (or did you mean the part where the cable slips in), but I am betting that it just popped the clip and disengaged somehow? I can't find any pics of how the clip goes on, but it's a pretty simple job to pull the gear, so I will do that in a while.

If anyone knows where to find a pic of the little ring clip, that would be great.
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Old 08-12-2017, 09:04 PM   #4
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Re: New 4L60 (YEA!) and speedo problems... :(

2-3 mph is the factory error built in to most older vehicles speedo's . unless certified for police use equipped .
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Old 08-12-2017, 09:10 PM   #5
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Re: New 4L60 (YEA!) and speedo problems... :(

http://sethirdgen.org/vss.htm
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Old 08-12-2017, 09:58 PM   #6
RedBed
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Re: New 4L60 (YEA!) and speedo problems... :(

The shaft of the gear snapped. I'll replace it!

I currently have 17/37 speedo gears.

At the GPS speed of 57mph, my Speedo reads 60mph.

So should I try a 36 tooth gear?
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Old 08-13-2017, 09:47 PM   #7
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Re: New 4L60 (YEA!) and speedo problems... :(

yeah one tooth is about 3 mph.
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Old 08-14-2017, 01:46 PM   #8
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Re: New 4L60 (YEA!) and speedo problems... :(

Bought a new gear, but I was originally wrong. I bought a 2-tooth larger gear (not smaller) because I need to slow down the Speedo. Will post results when I get it installed.

Thanks
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Old 08-14-2017, 08:54 PM   #9
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Re: New 4L60 (YEA!) and speedo problems... :(

Quote:
Originally Posted by RedBed View Post
When I removed the cable from the trans side, a very small wire ring (like a clip) fell out, so I have it in an envelope.

Any ideas? I might fix it myself if I can.

Also - He said it is currently 17/37 speedo gears. When my speedo reads 60, my GPS speed is 57. So would that mean I need to maybe a 17/36 setup?

THANKS
The wire ring (clip) holds the speedo gear shaft seal in place. Expand it slightly and slip it back into the sleeve down just touching to the seal.

You need a 38 tooth gear to get the speedo slower. 3 mph is an acceptable variance at highway speed if you check it at 35mph it is probably dead nuts on. Mechanical speedometers are never accurate through the entire spectrum. One tooth on the driven gear equals about 3 to 4 mph.
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Old 08-16-2017, 11:34 PM   #10
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Re: New 4L60 (YEA!) and speedo problems... :(

Went with a 39 tooth gear and dropped it in today. Damn near dead-nuts on now. Success!

But, of course, then I have another problem. Seems like the lockup is lurching or hesitating, but not sure. Back to the mechanic!
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