changing 85 mph speedo to 140

[stng87]

I am talking about changing just the speedometer in the cluster as I have one from a 93 140 mph cluster. How difficult is this to do? Thanks.

[skiwesser]

You can't put the 140 face on a 85mph speedo mechcanism, you have to get a 140mph unit(take the whole thing apart and switch the whole mech that the speedo cable hooks into). I'm not very happy with mine as after getting the 140 mech. $75 on e-bay,
& changing it all out my backlighting looked like crap, could'nd read all the numbers at night & the yellow on the tach was blinding. So I took it all out agian and after cutting off some misplaced plastic light directers and swapping brighter bulbs in some spots & dimmer ones in others it is a lot better but still is pretty crappy. A lot of hassle IMO.

[thdrcat]

don't.


i changed my 87's cluster for a 140 and still have wiring problems.

[stng87]

I am not talking about changing just the face, or the whole cluster pullout all-together. I am talking about simply switching the speedometer section in the cluster. Removing the 85 im place of a 140. This must be possible since they sell these seperately.

[Ackbar00]

Prolly the best way is to have BBK do it. It is like 170$, but at least it would work. Try here.

http://www.brothersperformance.com/s...nversions.html



Edit- Hmmm, said it was only 70$

[Terrifson77]

I'm running into a similar situation with my '88 GT resto project. As long as you have the speedo unit (the molded pot-metal mechanism on the back, and the black plastic sheet, you should be able to do it. Try removing the needle (carefully), swap the '87s for the 140 unit, and then carefully peel the black plastic faces off and exchange them. I'm not positive this will work, and it might and up lookin like crap as Skiwesser said, but hey, it's worth a try. Let me know if it works.

Jeff

[skiwesser]

Yeah you are right you have to change the speedo unit in the cluster to a 140 mph unit, still those plastic light directors must change with diffrent years because the 140 mph unit's did'nt even come near to some of the bulbs, all i know is mine was not what i expected and the faces were not the prob. (hold a flashlight behind just the face and it was perfect) But once installed and i saw it at night i yanked it out the next day,
I've had it out like 4 times and it as good as its gonna get,
great in the day but at night it looks x-tra ghetto

ps the actual swap is pretty easy & strightfoward
pps what kind of wiring problems everything plugs in nothing to wire but clean all plugs as i had a bad connection and the needles fluctuated on about removal #2

[stng87]

Im going to go out on a limb and say before I do this that it is going to work just fine. I see no reason why switching the speedo would cause any problems. We'll see...

[88GT 5pt0]

What I did was took the instrument cluster to a local shop, they changed the it over to 140mph for $40 then I put reverse glow gauges on there that go up to 140mph, and colored the lightbulbs red with a sharpie (so the needles were red at night). Look in the phone book, mine had a section for speedometers in the yellow pages. However when I drove past one of those signs the cops set up that tells you your speed my speedo was 5mph off, not too bad. It looks great