Cluster Upgrade: 88 Moons to 91 Needles

[Striker49]

I've been browsing the forums and net for a few days now trying to find some good how-to info on doing a cluster swap. I've got a bad temp guage on my 88 moonies and am tired of looking at em. I found a late model 91 with a cluster I'm buying out of it a few days from now which includes a tach. I currently have a dash-mounted tach.

Now, from what I've gathered, the swap should be pretty easy but I wanted to see if anyone else here had done the conversion and if they could give me better insight on the few random oddities that I have to change up to get the tach and such to work.

Thanks in advance!

[ShotgunFacelift]

Im in the same boat. Any help?

[sortasuave]

Check this thread:

http://www.fullsizechevy.com/forums/general-discussion/tech-articles/69806-update-94-gauges-w-tach.html

I'd think it'd be the same info as this one... Besides I thought the tach didn't come along till 94....

[xtremepimpin]

the cluster will plug right in but since you have a 88 and half way threw 91 they changed to needles some wires may be different,you will probley have to run a tach wire,and then the speedo calibration is more difficult to set ,i have a 91 and i just switched from moonies to needles with tach and i lucked out and it all worked,you would be better off going to the 94 gauges cuz the DRAC is cheapier to modify for speedo calibration,cuz the 91 cluster the calibration kit is very sparce since they quit making them

[Striker49]

I picked up a diagram for the rerouting of the wires for the 91 cluster off the forums here somewhere, but as to where that piece is located I don't know. Keep in mind I already have a tach wire ran since I have the dash mounted tach. Id rather not goto the 94 cluster, since from what I've read, is much more complicated to get working than the 91 cluster.

[hornsfan10609]

Ditch the other tach. GM first offered the needle gauges with a tach in 91 and you got the only year the clusters were made with the same plug as the 88-91 trucks. You just have to change a couple wires around and the cluster should work.

[Striker49]

Yea, I plan to ditch the dash-mounted tach I have now in place of the factory styled one. If I dont manage to grab any info in the next couple days, Ill fool with it and hopefully write up a good how-to.

[91chevZ71]

FWIW, I swapped out my moonies for a tach cluster directly with no changes, works great. 1991 truck. I lucked out and found a 1991 cluster with tach so no changes were needed.

[lowdown]

You will have to swap some wires around on your 88 or it will not work.

The information for this used to be posted on 454SS.com but last time I looked it seems to be gone.

I set up a page with the information you need to install the 91 cluster, you can find it here:

http://www.koolcartoons.com/lowdown/speedo/91cluster.html

lowdown

[Striker49]

Exactly what I was looking for, thanks! Do I need the additional parts to reprogram the speedo or can I just leave it set as it is now?

Just want to clear up as many questions as possible before I dive into this on Monday. Thanks again!

[JohnO356]

You can leave it as it is. Just follow a friend at a few different speeds to find out how much off the speedo is, and keep that in mind on the road.

[Striker49]

Ok, bout what I figured. If anything, I'd time myself on mile-markers.

Thanks for the help yall, I appreciate it! Wish me luck tomorrow.

[Striker49]

Well, everything went fairly smoothly but it looks like the cluster came out of a 4x4, probably with a 3.73 rear end, so the speedo is off. Rewiring and all was fairly straight-foward and simple. Had to do some cutting on the dash to get the harness out to rewire, but no issue. I also got a harness from a local junkyard for free and used a connector from it to tap in my tach wire. Now I have to find the recal kit so I can get the speedo reading more than 25mph while I'm actually going 55ish. Thanks for the help guys, it's much appreciated!

[JohnO356]

Glad you got it in. Your local dealer may be able to find you a calibration kit on his computer if he doesn't have one. They're getting hard to find.

[Striker49]

Not much luck. Cost me $100 to "possibly" get it shipped to a local dealer, but unlikely and I had another deal trace down the parts and there arent but a few left in inventory on the GM records in the country, and the closest of both parts is over an hour from my place. All-in-all, it'll be cheaper if the dealership can actually get them for 100, but I really really dont want to spend that, but its looking like I have no choice. Had no luck on EBay either. May try to call around some random places tomorrow and see if I can find anything, but this is getting dumb.

[JohnO356]

One of the local dealers here gave me about 6-8 dealer phone nrs around the country who had them . A few of those I called didn't want to sell them "in case they needed them in house". A dealer in Little Rock mailed me the whole kit, including two chips for $14 total. A big price mistake on his part but I'm not complaining. The things are good for 8-10 uses, but I tore mine apart to use one of the connectors for my tach. Wish I hadn't.