YET ANOTHER OBS Instrument Cluster Question!

[mook62]

Hey folks,
Bear with me. I've just got through searching and reading everything I can find about gage cluster swaps for the OBS trucks. After all of the reading,

Now, correct me if I'm wrong. Here's the deal. I have an 88 Silverado with some odd ball option combinations (thats another story!)it's a RCSB but has rear window defroster,factory trailer hitch, full power.

Anyway, the truck is equipped with "Moonies" that only go to 85 MPH. I have a line on a SS454 cluster out of a 90 model that is in good shape. They are "Moonies" as well.

Can anyone give an opinion as to whether or not the swap will be a plug and play?

Any help is appreciated.

[Menard666]

Well, I've read a lot into this and I would say that yes, that cluster will swap right in, but I ask why would you swap from moonies to moonies? For a higher MPH reading? IMO, I'd swap to needles if you're gonna bother.

[WhiteBrow24]

ya dont go moonies, i have them and they are worthless and look dumb for a lack of better words. get a nice needle set with a tach, youll be much happier

[mook62]

Points taken regarding swapping from Moonies to Sweepers.

Here is some of the reasoning behind swapping Moonies for Moonies.
1. I want to upgrade to a higher MPH, but want it to be "period correct" for the approximate model year of the vehicle.

2. I currently don't have a tach and see no need to have on in my cluster swap.

3. I don't want to hack into the harness and add wires or change harness connectors or have to worry about addign a Drac module.

My master plan (everyone has one, right??) is to buidl the truck into a SS305 if Chevy had of built one in the late 80's early
90's.

I'm in the process of reworking the 305 in it to Vortec heads, Eldelbrock Victor Jr. Intake with a TBI adapter and a Comp Cams Xtreme Energy cam. I'm keeping the TBI and adding a recurved Distributor and MSD 6AL system. The T700R4 will stay; but be rebuilt with a mix of B&M parts and Corvette parts to raise the presures for firmer more positive shifts.

With all the research I've done, this combination will give me a 290 to 300 HP at the crank so I can see about 225 to 240 HP at the rear wheels. That's assuming a net loss of 25% to front end parasitics and slushbox ineffiencies. My goal is SIGNIFICANTLY better performance out of my 305 with on highway mileage of around 20mpg.
From everything I have read, this is very possible if not probable with the mods that I have listed.

So, in keeping with my theme. That's why I thought of going with the unpopular Moonies but just getting a better looking (read that as cleaner and unmolested) gage cluster.

[Menard666]

I see your point in keeping it "period correct", but how many people will even notice if you don't tell them? All "molested" parts will be hidden away behind the cluster, the only person that will know is you, and you could do a very clean install if the time was taken. I have the moonies in my '91, and I have a cluster from a '92 sitting on the floor. It has 0 miles on it, and no tach. It really pleases the eyes staring at it, rather then the large white strips of the moonies. Plus you can add LED's to change the colors of the gauges to match your truck. IMO sweepers/needles are the way to go, and the engineer that invented the moonies should be caned in public.

[Buffalo]

One other thing to think about, your speedo is most likely going to be off if you do the moonie to moonie change. Gm used to sell a kit to correct this, but it is my understanding that this kit is no longer made and is difficult to find. If you switch to the needle style, you will have a DRAC and will be able to correct the speedo now, and also have the ability to change it later if you change tires or gear ratio's down the road.

Plus they just look better...
http://buffalolake151.20fr.com/gauge%20015S.jpg

[Roehl_909]

One other thing to think about, your speedo is most likely going to be off if you do the moonie to moonie change. Gm used to sell a kit to correct this, but it is my understanding that this kit is no longer made and is difficult to find. If you switch to the needle style, you will have a DRAC and will be able to correct the speedo now, and also have the ability to change it later if you change tires or gear ratio's down the road.

Plus they just look better...
http://buffalolake151.20fr.com/gauge%20015S.jpg

I love that cluster! Where did you get it? Did it come with the blue needles?:drool:

[mook62]

Buffalo,
Just curious, but if I swap Moonies to Moonies, why would I be off? All of the tire sizes and rearend ratios on the 1/2 ton trucks 88 to 90 were within 10% of each other. The gage's accuracy should be somewhere in the +/- 5% range.

And guys, I do agree. I Like the sweepers! I've had an extremely hard time trying to find a set of sweepers without the tach.

I have been narrowing my search qutie a bit though to just trucks. Maybe if I include Tahoes, Suburbans, Escalades I might have better luck.

I think that part of it may have been the DRAC module phobia. I'm just a little apprehensive about cutting into a wiring harness.

Thoughts?

[Menard666]

Yah, you're not really cutting into a wiring harness, think of it more like changing ends that plug into the gauge cluster. Simple clip and solder as long as you've got the wiring diagram in front of you. What gears came in the 454ss? If they're not the same as what you're running then the speedo will be off. With a DRAC it's all adjustable, so you won't have to worry about it. eBay is a good place to get clusters. If you wait long enough, the odd one with zero miles comes up.

[Menard666]

This is the same guy I bought my cluster off of. Stand up guy, packaged really nicely and no miles on it. Just FYI incase you changed your mind. You will still need a DRAC and the Connector with wires from another truck.

http://cgi.ebay.com/ebaymotors/CHEVROLET-TRUCK-SPEEDOMETER-CLUSTER-GAUGES-CHEVY-C-10_W0QQcmdZViewItemQQcategoryZ33675QQihZ013QQitemZ230114035010QQrdZ1

[Buffalo]

I love that cluster! Where did you get it? Did it come with the blue needles?
This is just a standard cluster from a '92. I bought a Nu-Image gauge face on Ebay for $79, and a stainless steel cover on Ebay for $9.95. I cleared the needles myself, and colored them with a sharpie. But I have had a little trouble with the needles showing up good at night. I have currently changed them to red for more contrast.
Just curious, but if I swap Moonies to Moonies, why would I be off? All of the tire sizes and rearend ratios on the 1/2 ton trucks 88 to 90 were within 10% of each other. The gage's accuracy should be somewhere in the +/- 5% range.

Not necessarily, your new speedo may not have come from a 1/2 ton. You could easily have a 1990 1/2 ton that came with a stock 225/75R15 tire (28.3" high) and a 3.42 gear ratio. The new speedo could come from a 1990 3/4 ton with a stock 235/75R16 (29.9" high) with a 4.10 gear ratio. The input ratio for the 1st speedo would be 0.756305 to make it read correct. The input for the second would be 0.858486 to make it read correct. On my truck I run a 265/75R16 tire with a 4.10 gear ratio (30.5" high). My input ratio is 0.810044. However, 0.810044 is not a ratio offered by GM. I can either go to the 0.808594 ratio and be 7 mph slow, or go to the next setting up of 0.817671 and be 10 mph too fast. I have used actual mileage markers on long trips using both the 0.808594 and 0.817671 settings to determine the 7mp and 10mph differences. So the 0.756305 to 0.858486 would be a major change.
I've had an extremely hard time trying to find a set of sweepers without the tach.
I spent over 3 months searching Ebay for the right cluster for mine, because I wanted one with the same mileage as my truck. I eventually found the one that I was looking for, but I saw more gauges without the tach in that time than I saw gauges with a tach.
Yah, you're not really cutting into a wiring harness, think of it more like changing ends that plug into the gauge cluster. Simple clip and solder as long as you've got the wiring diagram in front of you.
I agree. If you take your time, make sure that have the right diagram, then cut-solder-shrinksleeve 1 wire at a time you'll do fine.

[Joe Dirt]

Points taken regarding swapping from Moonies to Sweepers.

Here is some of the reasoning behind swapping Moonies for Moonies.
1. I want to upgrade to a higher MPH, but want it to be "period correct" for the approximate model year of the vehicle.

2. I currently don't have a tach and see no need to have on in my cluster swap.

3. I don't want to hack into the harness and add wires or change harness connectors or have to worry about addign a Drac module.

So, in keeping with my theme. That's why I thought of going with the unpopular Moonies but just getting a better looking (read that as cleaner and unmolested) gage cluster. Damn, you sound like me. :crazy: I agree with the period correct comment, that's one of the reasons I got a 1990 454SS cluster to go in my '90, the other reasons are I kinda prefer the looks of the "moonies" over the "sweepers," and I didn't want to hack up my dash wiring harness. Besides, I have a tach/shift light mounted below the dash for when I need a tach. :D

I see your point in keeping it "period correct", but how many people will even notice if you don't tell them?How many people will notice that he put "sweepers" in a '88 model truck if he doesn't tell them? I'm going to take a guess here and say the same people that would notice he put a '90 454SS cluster in a '88 model. :smokin:

[Buffalo]

can either go to the 0.808594 ratio and be 7 mph slow, or go to the next setting up of 0.817671 and be 10 mph too fast. I have used actual mileage markers on long trips using both the 0.808594 and 0.817671 settings to determine the 7mp and 10mph differences.
I'm sorry, I should clarify a little more. On the setting up of 0.817671 my odometer would register 110 miles for every 100 miles actually driven. The 0.808594 ratio would register 93 miles for every 100 miles driven.