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Replacing speedo/tach needles in cluster on '92 GTP - how to align?


crazyd

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Has anyone here ever disassembled or replaced the indicator needles on the speedo/tach and had to realign them? Mine are all screwy and it's driving me crazy - there must be a better way than trial & error!

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Trial and error. I've done it before with my tach needle- at hot idle, I think the LQ1 sits around 750 rpm... so set it on there approximately where that should be. I'm assuming you have HUD? Set the cruise at 55 and press on the needle there. :lol:

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Just out of curiosity, how far off are they? I need really need to adjust the ones on the 90. Ever since I put the UB3 cluster in, the speedo/tach have been wrong. I thought it was a bad cluster but maybe I'll try this.

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Hmm, so in my car if I'm doing 55 it says about 85. Should I be thinking of doing the same thing as you guys and just adjusting the needles? I thought I needed a cluster or the harness was pinned wrong.

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Why not?!? Have you ever owned a 20-year old car built by a bankrupt company?

 

He's owned several. :lol:

 

And "new" doesn't necessarily mean BRAND new. Junkyards/eBay/Craigslist.....

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Hmm, so in my car if I'm doing 55 it says about 85. Should I be thinking of doing the same thing as you guys and just adjusting the needles? I thought I needed a cluster or the harness was pinned wrong.

I'm not sure if this affected the Luminas of that vintage too, but the first year Pontiac went to the sport cluster with needles (in 1990), the 1990 clusters are horribly inaccurate. The best fix for them is to swap in a 91-93 cluster.

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there are two potential problems with any of these clusters.

 

the most common one is the calibration resistor being junk. with that issue, the speedo (and tach) are generally correct at 0MPH/0RPM, but as they rise, they are off by a certain percentage at all times. fixable with a pair of 500K potentiometers(i would choose 15 turn versions).

 

the other issue is if the needle for some reason is not correct even when at 0. that i've never had to deal with personally.

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Hmm, so in my car if I'm doing 55 it says about 85. Should I be thinking of doing the same thing as you guys and just adjusting the needles? I thought I needed a cluster or the harness was pinned wrong.

The needle being off would mean that at 55 it says your doing 85 and at 15, your doing 45... If the resistor (or whatever Saar mentioned, it will be off by 20% or more which means at 15, it would read closer to 20, make sense?

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in that situation(bad resistor assumed), the speedo reads roughly 54.5% faster than in reality.

 

so:

real - read

10 = 15

20 = 31

30 = 46

40 = 62

50 = 77

60 = 93

70 = 108

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You're about dead on with the numbers actually yes. Here's how it usually reads.

 

10 = 15

25 = 35

35 = 45

45 = 62

55= 75 (sorry not 85, was just looking at a pic.. I dont have access to the car until 4/15)

65 = 85

75= 95ish

 

I do have a 91-94 cluster, maybe I'll try that in there and see how it acts. The one I bought came from Ebay and was like $5 so maybe that's why.

Edited by 3pt1lumina
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Once I can physically get my hands on the car I'll post. I don't know how to use one but I'm sure I can learn plus might be good for others on here who don't know either. Thanks for the info.

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So here's the full story, now that I've got some more time to talk about it. The problem is finding a REAL GTP 3.4 cluster in perfect shape. I have been patiently acquiring clusters from various sources, and each one of them has something wrong with it - so it's pretty annoying when someone says "just buy a new one!" because it doesn't answer my question and insults my intelligence and hard work up to this point.

 

Here's what I have:

 

- The first one is from a 3.1 GT. It has a 6k redline instead of 7k, its trip odo is broken and it has the flickering "CHECK GAGES" and low fuel indicator problem, BUT its needles were all orange.

 

- The second cluster came from an STE, and the STE's oil pressure gage is different, but its trip odo works and it doesn't have the flickering problem, but its needles had all yellowed.

 

- My original cluster has a broken trip odo, yellowed needles, AND the flickering problem. But it has the right redline and the right oil pressure gage.

 

I wanted to take all the good stuff from each of these and make one good cluster, that would have the right oil pressure gage, the right redline, orange needles, a trip odo that works, and no flickering indicators (yes, I know about the supposed fix for this, but I tried it and it didn't work on either of these boards).

 

I worked on it some more today and I think I've got everything lined up now. The best way seems to be to remove the clear front cover, leave it plugged in and connected, power it on, then hold the needle with your left hand at the '0' point while finding the shaft and pressing it on with your right hand. Then shut it off and press them on firmly with your thumb, because they will come loose if you don't.

 

I still haven't had any success with the trip odo, though. Turns out some marketing genius at GM thought that the odo/trip mileage indicators should be 1/8" further to the left for the STE cluster than for the GTP cluster, presumably for a very important brand-attribute reason, and thus trying to swap them results in them being unreadable through the cutouts. :think:

 

So anyway, my hope was that there was an official gage-calibration procedure, but I guess nobody here knows what it is.

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probably because tampering with that stuff is a big no no. there are several companies out there that fix this stuff. instead of messing around with it, why not just send it to a professional who knows what they are doing?

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probably because tampering with that stuff is a big no no. there are several companies out there that fix this stuff. instead of messing around with it, why not just send it to a professional who knows what they are doing?

 

Because it isn't rocket science, and because those same "pros who know what they are doing" have, in my experience, more often screwed it up than not.

 

My work was a success by the way, the Speedo and tach are dead-on accurate now, everything works, the flickering has stopped both on the cluster and the HUD, and the needles are all orange instead of faded yellow.

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