V8 / V6 VR instrument cluster and speed alert

[rickybobby]

hi,

trying to sort out previous owner shenanigans with a VR V8.

- speedo is reading higher than actual speed
- speedo reads 116 while GPS (and other cars and freeway speed check) reads 110
- speed alert is functional and accurate and different from the speedo (speed alert matches GPS)
- speed alert background light does not work (alert light is ok and beep is ok)

a) can somebody please confirm that the V6 and V8 instrument clusters are different (on this particular car the original V8 cluster has been replaced with a V6 cluster) - do i need to find and install a V8 cluster ? are the speedo electronics different inside the v8 cluster ? it's looking like they are...

b) speed alert is accurate enough but i can't see the display at night - i'm also suspecting that the V8 and V6 speed alerts are different parts - does anybody know for sure ? the speed alert that is currently installed (v8 factory ?) has homemade soldering on it and it's not as easy as it should be to simply replace the background light. do i need to hunt down a V8 specific speed alert ?

thanks for any info, feedback, links to other threads or ideas,
rob

[westbad]

the only difference between V6 and V8 clocks is the tacho, it will read about 800-1000rpm more than your actually doing if you have a V6 clocks in a V8, the speedo should be the same as should the speed alert, you can convert the V6 tacho to read V8 RPM but this involves some soldering.

Most commodores ive been in read more than there actually doing, apart from my ss.. which actually reads a few kms slower than im going.

[88GreenVN]

I'd say 6 kph out is not uncommon.

The speedo head is the same for v8 to v6. Infact I think you can run VN to VS speedo's head in any VN/P/R/S L1/2 cluster.

[rickybobby]

thanks for replies

i can live with tacho reading a little high for the moment (which it does as suggested) and the speedo must just be 10% crap (my other car VN V6 speedo is surprisingly accurate +/- 1%)

will try another speed alert in the VR V8 with a functional background light (it came out of a vs v6) - hopefully it will also be +/- 1%

what i'm wondering about now is...

vr v8 car has abs and airbag factory fitted which aren't lighting up on the replacement v6 instrument panel when starting or any other time

are there abs and/or airbag model specific instrument clusters ?

thanks again for any info..

[Fonzie]

The other thing to check is, where's the needle when you're stopped? I've seen cars where the needle has been removed and replaced in the wrong spot.
As for the speed alert light... Should just be a simple globe change. Failing that, there'll be a break in the wire somewhere. You could trace it, or easier would be cut the positive illumination wire at the speed alert and wire it to another somewhere behind the dash that has tested OK.

[rickybobby]

had a bit of a fiddle and here is what is happening - thanks again for replies - they helped heaps and were spot on.

a) exec VR V6 cluster instrument lights are all ok in VR V8 with abs,airbag
abs and airbag lights/circuits are all good (i was simply missing globes in V6 replacement cluster)

b) v8 cluster speedo is same as V6 cluster speedo and in this case is crap
i tried very accurate vn v6 speedo cluster in vr v8 and it's good

c) vn v6 and vr v6 cluster tacho are both reading too high when installed in Vr v8 - i'll investigate simple solder fix later but can cope with this at the moment.

d) the speed alert in this particular vr V8 has dodgy internal background light modifications (colours and flashing and homemade solder resistors, etc.) and the background light cannot simply be inserted into the circuit board as it should be - however, a complete cheap replacement speed alert from the wreckers (vs v6) works fine in the vr V8 so it's all good at the moment.

cheers.

[slepar]

does your car have standard 3.08 diff gears?