Brick nose speedo

laserjock

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So, I have an issue that has gotten progressively worse. My speedo started out perfect dead on by GPS. Then it started bouncing around at higher speed (over 65). That has progressed to now it’s basically pinned at 55. Won’t go much over that. I’m quite sure that I didn’t drive 400 plus miles of interstate at 55 the last 2 days. My trip gauge would also seem to be way behind as well. It seems to me like it has to be the gauge. If it were a cable issue you would have thought it would have just broke by now.

What say the collective?
 

IDIBRONCO

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Just a guess here, but could it be your speedo gear in the transfer case? or the one on the end of the cable?
 

pelky350

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Mine went bouncy and not working correctly when my truck went further than the guage reads lol it's still bouncy and off to this day
 

laserjock

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Well, I wondered if I hurt the gauge when I started it in gear without the driveshaft in on the last reassembly. It running okay then dropping bouncy then running okay makes me wonder what’s going on.
 

no mufflers

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I have one I looked at and if the speedo is slow then the miles will match, unless there are some parts in the gauge that are completely FUBARed.

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Shadetreemechanic

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Well, I wondered if I hurt the gauge when I started it in gear without the driveshaft in on the last reassembly. It running okay then dropping bouncy then running okay makes me wonder what’s going on.
That is intermittent drag on the cable. Try taking it out, clean, lube and reinstall.
 

ifrythings

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I got rid of the cable and having to find different gears when you changed tires
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Thewespaul

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Hmmm maybe swap to a second or third gen 10.25 and convert over to a vss run speedo, two birds with one stone. Could really help your rear end problems
 

laserjock

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My truck has the sensor in the rear diff. It was out of an E4 truck but I thought all the rabs trucks had that sensor??

The updated speedo is ****. Does the odo work?

If the cable dragging would cause that, wouldn’t you think it would wind up and break after a couple hours pinned low?? I guess it could have been slipping enough to release the tension but not enough to move the needle.

I have never lubed a speedo cable. I thought they were pre-lubed. What do you lube them with??
 

ifrythings

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My truck has the sensor in the rear diff. It was out of an E4 truck but I thought all the rabs trucks had that sensor??

The updated speedo is ****. Does the odo work?

If the cable dragging would cause that, wouldn’t you think it would wind up and break after a couple hours pinned low?? I guess it could have been slipping enough to release the tension but not enough to move the needle.

I have never lubed a speedo cable. I thought they were pre-lubed. What do you lube them with??

Everything works on the Speedo including programmng it for new tire sizes and the odo/trip works too, very simple to hook up also, ground, ignition, battery constant and the 2 wires to the vss and the vss output to ecm/cruise works also.

For the Speedo cable use a dry graphite lube to lube the cable, common problem is the cable binds slightly which causes it to accelerate abruptly and the speedometer portion is very senstive to acceleration changes and is shown as bouncing on the needle, you will notice your odo is accrate throughout this.
 

79jasper

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My truck has the sensor in the rear diff. It was out of an E4 truck but I thought all the rabs trucks had that sensor??

Right. I think it's actually the same sensor between the two. It's just a matter of the psom and stuff.

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