Speedometer Help

Hi,
I just installed a instrument cluster and speedometer cable from a 88 Cherokee in my favorite old XJ/ project jeep, a 1984 jeep Wagoneer. The printed circuit on the old instrument cluster bit the dust and was peeling away from itself, half of the illumination and gauges didn’t work when it was pulled out.
Everything with the new cluster works great now, except for the speedometer. The speedometer is way off.

It has np-207 transfer case, 3.73 axle gears, 30X 9.5 X15 tires.
The old speedometer was only off by 5 mile per hour, if it read 40 mph it was actually 45. The new one reads much lower then actual speed, still don’t know by how much yet, I have to borrow my brother in-law’s GPS.
Pulled the speedometer gear and it is a small plastic 20 tooth (green?) gear.


How can this be fixed?
Is there a correct speedo gear available ?


Thanks for any help, Paul.
1984 XJ Wagoneer, 2.8 V6, 5speed, np207, 3.73

Re:NP207 Speedometer Help

Ok, same problem different idea.
From what I understand there is not a great range of speedo gears available for the NP207, 21 tooth to 18 tooth (?) or there abouts. Any way for a new tact, what about changing the gear in the transfer case (drive gear) that turns the speedometer gear (driven gear) ?
This is the speedometer drive gear from a np207 that had an automatic transmission.





I imagine that it would either be the same or similar to one with a 5sp transmission.
Is there a way to replace the gear inside the transfer case with one that is a closer match for what I need?
Also does anyone know the Revolutions per minute (RPM) ,turns of the cable, to register 1 mph on the 1984 speedometer and/or the 1988 speedometer?
From what I’ve been told there should be a mark on the bottom face of the speedometer, something like 850 or 1000. I can find no such a mark on either of the speedos.

Would any parts from a s10 or something else that used a np207 work?

Paul.
1984 XJ Wagoneer, 2.8 V6, 5speed, np207, 3.73

Re: NP207 Speedometer Help

If nothing else a Speedo shop will have these little "adjuster/adapter/conversion" boxes available.They go inline with your current cable set-up.

Re: NP207 Speedometer Help

RCP Phx said:

If nothing else a Speedo shop will have these little "adjuster/adapter/conversion" boxes available.They go inline with your current cable set-up.

Click to expand...

Yep,
Just recently seen them online, holding that off as a last resort. Kinda hoping that there is a factory or nearly factory way to make this work. Fits with my sense of the way things should be, might have welded a Ford 8.8 LSD in there but it was the factory 3.73
But it doesn’t really matter, fixed is fixed. Once I know by how much the speedometer is off, hopefully this weekend, and no other fix presents itself, I’ll try to get an adaptor that will work. Doesn’t have to be perfect, just closer to accurate.
How much should these adapters cost?
Seen them online for around $70.

1984 XJ Wagoneer, 2.8 V6, 5speed, np207, 3.73 & 1991 4.0 automatic np231

Problem solved!
unfortunately the first clusters' speedometer was defective in some manner. I picked up another cluster (out of a 89XJ) last week from a junk yard cause it just looked better. Popped it in Saturday and gave it a test drive today. According to GPS it is only off by 2.3 mph! Not the 20mph slow the other was. Now at 45mph it is actually 47.3 or .4