120 MPH Speedometer Upgrade

[flint54]

Notes From Minuit:

- This upgrade is possible on 1991 through 1996 Cherokees and Comanches only. The 120 MPH speedometer discussed below was only available on 1993 through 1996 United Kingdom market Cherokees. Cable-driven alternatives may exist, but are outside of the scope of this writeup.

 

- As discussed later in this thread, this swap is not applicable to instrument clusters from 1991 model year vehicles. If you are interested in performing this upgrade on your 1991 vehicle, a 1992 through 1996 instrument cluster is compatible with a 1991 vehicle and will accept the 120 MPH speedometer.

 

As the topic says, I wanted one, and, thanks to fellow member Jim, I now have it.

This one came from a 1994 UK cluster and the swap into my 92 was total plug

and play, no modifications whatsoever. So, here's a few images of the details:

 

First the "donor cluster (note the temp and oil gauge units):

 

Cluster removal and speedo removal didn't warrant their own images, so next

is an image of the backside of the removed 120mph speedo:

 

Next, observe the UK foil circuit, in particular the three terminals for the speedo:

 

USA foil circuit looks like this, with my marks showing the difference:

 

Backside of the removed 85mph speedo looks like this:

 

This is where the epiphany took place - note the white interface adapter that makes

the units interchangeable between the two clusters and foils:

 

Swapping the adapter was three screws easy. Just as easy as three more screws

to install the 120mhp speedo into my cluster, then the cluster back into the dash:

 

To my astonishment, the drive test showed the new 120mph unit to be very accurate,

based on previously made RPM comparisons for every 5mph between 35 and 85. On

top of that, the odometer and trip meter are also accurate.

 

There's now only two things left to do:

A) send unit to these folks to have odometer reset to my mileage: http://www.gaugeguys.com/

and

B) continue modifying the truck so that it may someday actually achieve 120 mph.

[Exgrayxj]

Didn't I say...I think it will be plug and play? Why would they change that?

 

Not that I had ANY idea...glad it worked out for you, though I wish more that it would have worked in super Waggy.

 

:cheers:

 

Jim

[Rymanrph]

Can you not change the mileage yourself? When I swapped in a new cluster, I was able to disassemble the odometer and spin the wheels to the right mileage.

[Alexia]

Can you not change the mileage yourself? When I swapped in a new cluster, I was able to disassemble the odometer and spin the wheels to the right mileage.

 

Depends on the cluster. At some point they changed to welding the plastic together so it would break it you tried to disassemble it. Granted, glue can fix it! Also could just grab an older speedometer that can be disassembled easily.

[Jeepyjeepy]

I'm not up to snuff on the difference between clusters from renix and hos but am curious if It would work the same

[HOrnbrod]

I'm not up to snuff on the difference between clusters from renix and hos but am curious if It would work the same

No. The Renix speedo is cable driven mechanical, HO is electronic.

[Comanche County]

Good write up!

[TexanEliminator]

Well guys unfortunately this does not work on a 1991 I guess. The little adapter in the above pics does not exist on my speedometer or the 120mph speedometer that I got from a member on here. The circuit boards are completely different and in no way interchangeable.

[Minuit]

3 minutes ago, TexanEliminator said:

Well guys unfortunately this does not work on a 1991 I guess. The little adapter in the above pics does not exist on my speedometer or the 120mph speedometer that I got from a member on here. The circuit boards are completely different and in no way interchangeable.

Very interesting. My swap went exactly the same way as described in this writeup, but my US cluster came from a 1996 XJ.

 

That makes me think the '91 cluster is different from 1992-1996. The whole cluster interchanges '91-'96, but the individual parts might be '91 specific. If you can get your hands on a newer cluster than 1991, I suspect you'll be just fine.

[TexanEliminator]

Just now, Minuit said:

Very interesting. My swap went exactly the same way as described in this writeup, but my US cluster came from a 1996 XJ.

 

That makes me think the '91 cluster is different from 1992-1996. The whole cluster interchanges within that range, but the individual parts might be '91 specific. If you can get your hands on a newer cluster than 1991, I suspect you'll be just fine.

So do you think a cluster from a 92-96 would work in my 91? I really don’t want to give up yet because I already sent the 120mph speedo to get programmed to my mileage! 

[Minuit]

Just now, TexanEliminator said:

So do you think a cluster from a 92-96 would work in my 91? I really don’t want to give up yet because I already sent the 120mph speedo to get programmed to my mileage! 

Yes, any cluster from 91-96 will fit in your truck. I have a '91 too, but my truck came with idiot lights originally, so I had to buy a HO full cluster to swap in, which came from a '96 - plug and play into my truck, other than replacing the gauge senders. Later on I swapped the 120mph speedo into the '96 cluster. No problems and it was plug and play.

[TexanEliminator]

4 minutes ago, Minuit said:

Yes, any cluster from 91-96 will fit in your truck. I have a '91 too, but my truck came with idiot lights originally, so I had to buy a HO full cluster to swap in, which came from a '96 - plug and play into my truck, other than replacing the gauge senders. Later on I swapped the 120mph speedo into the '96 cluster. No problems and it was plug and play.

So from what I gather from reading this thread over and over again from the beginning, the white “interface adapter” comes from the 85mph speedometer and not the 120mph one correct? I’ve found a cluster on eBay from a 1994 and am about to pull the trigger. I just want to make sure my 120mph isn’t what’s not compatible.

[Minuit]

1 minute ago, TexanEliminator said:

So from what I gather from reading this thread over and over again from the beginning, the white “interface adapter” comes from the 85mph speedometer and not the 120mph one correct? I’ve found a cluster on eBay from a 1994 and am about to pull the trigger. I just want to make sure my 120mph isn’t what’s not compatible.

Correct.

[TexanEliminator]

Just now, Minuit said:

Correct.

Thank you so much! I can tell from the pics online that the newer cluster is missing the 3 copper colored bigger screws into the back because they are on the adapter and the whole assembly is held in by the 3 small chrome screws. On mine, all 6 screws hold the speedometer to the gauge cluster. Gonna order it now!

[TexanEliminator]

One more question. The cluster I have picked out online seems to have far fewer light bulbs in the info center area. Possibly from a 2wd low option Cherokee. Should I feel confident that the foil is the same and will light up all lights that do on my current cluster as long as I have the bulbs in place in the correct spots?

[Minuit]

10 minutes ago, TexanEliminator said:

One more question. The cluster I have picked out online seems to have far fewer light bulbs in the info center area. Possibly from a 2wd low option Cherokee. Should I feel confident that the foil is the same and will light up all lights that do on my current cluster as long as I have the bulbs in place in the correct spots?

The "foil" will be there, and all of the lights will light up correctly so long as the bulb is there even if they are in different places. If the new cluster is missing a bulb, you can just transfer the bulb holder over from your old cluster. I don't think the MAINT REQD "replace the O2 sensor" light will be there, but nobody cares about that one anyway.

 

When going from my original '91 cluster to the '96 cluster, the only real difference I noticed was that the check engine light was orange instead of red. Some of the warning lights were in different spots, but it all worked out.

[schardein]

I've reset the odometer on 91-96 speedometers.

 

You have to sacrifice a speedometer and pull out a small metal shaft with a plastic drive gear on it.  Put that in an electric drill.  Then lay the speedometer you want to adjust on a folded shop towel.  Lay the drill next to it on a folded shop towel, so that the two gears mesh.  Turn the drill on.  Check periodically.  Helps if the replacement speedo's odometer is close to your desired mileage.  Also helps if the drill is variable speed so you can go slower than full speed.

[TexanEliminator]

I'm happy to report that I got my swap completed. The 1994 cluster that I got off ebay had the adapter for the 120mph speedo and it fit right in and works perfectly! I did spin the odometer that came in the 1994 cluster to see if it was possible to adjust it. The numbers spun freely although slowly. I sent the 120mph odometer off to get calibrated to my mileage but because of the additional week delay in ordering the 1994 cluster, my mileage is short about 2000 on the 120mph speedo. I was too scared to spin the numbers by hand on an odometer that I knew would be next to impossible to replace. Can anyone confirm that spinning the numbers manually will not damage the odometer?

[schardein]

On 8/24/2019 at 8:19 AM, TexanEliminator said:

I'm happy to report that I got my swap completed. The 1994 cluster that I got off ebay had the adapter for the 120mph speedo and it fit right in and works perfectly! I did spin the odometer that came in the 1994 cluster to see if it was possible to adjust it. The numbers spun freely although slowly. I sent the 120mph odometer off to get calibrated to my mileage but because of the additional week delay in ordering the 1994 cluster, my mileage is short about 2000 on the 120mph speedo. I was too scared to spin the numbers by hand on an odometer that I knew would be next to impossible to replace. Can anyone confirm that spinning the numbers manually will not damage the odometer?

Did you read my post right above yours?

 

I spun the odometer of an electronic speedometer with a scavenged gear in an electric drill.  It did not damage it.

[Limeyjeeper]

I used a dremel with the rubber round sander attachment. Worked great. One point to note some 91 dashes like mine. Were not compatible. So I swapped the complete donor cluster. 

The early 91 had a different circuit board setup so even changing the white cover didn't help. So I had to find a 1993 US cluster and used that for the swap. See below for some pics of the differences.

 

91 US

 

UK