85mph to 140mph SPEEDO UPGRADE

[chgostout]

I am under the impression (from reading in the corvette black book), that ALL the speedo's in 1980 were made to read no higher than 85 mph., but for how many years were they like this before they went back to their standard?

I just bought an '80 with what I now have to assume, from reading alot the the threads in this post, is an upgraded 140 mph. speedo. Because of this, I guess I have to take the guy's word for "the car" having 46.000 "original" miles on it, because if he or someone before him did change out the speedos, ... it's anyone's guess about what the TRUE mileage on the car could be.

Now I don't know what to think.

Can any of you enlighten me about the true facts about whether all '80 vettes were given this 85 mph speedo? And how long were they put into the cars? And how i might be able to recognize this 140mph one as "authentic" to this car or how old it might be? It does have the corvette insignia on it.

Thanks

 

[rgtrough]

speedo answer

Hey guys, my 1974 sharks' original speedo has 160 in white numbers. I am looking for a tach from a 1975 if anyone knows of one please contact me. peace :cool
Bud

 

[Dave L.]

Mike - Beginning it late 79 they started putting those 85 mph speedos in corvettes up to and including all 82's. Does the 140 mph speedo you have in your car now have blue kilometer markings? That is not the original speedo that came from that car from the factory. I remember back in 1980 when I had just started working at my present location that guys were buying the 'early' 79 speedos and transplating them in their new 80's.

Dave

 

[Evolution1980]

...ALL the speedo's in 1980 were made to read no higher than 85 mph., but for how many years were they like this before they went back to their standard?
Can any of you enlighten me about the true facts about whether all '80 vettes were given this 85 mph speedo? And how long were they put into the cars? And how i might be able to recognize this 140mph one as "authentic" to this car or how old it might be? It does have the corvette insignia on it.
Thanks

ChgoStout,
ALL 80-82's had 85mph speedos, as it was a federally madated change. (GM took a break in '83). When the vette re-emerged in '84, it was digital. So only the 1980-1982 had 85mph speedos. Here is a before and after picture.

Notice the original yellow sub-numbers on the 85mph unit, versus the blue digits on the 140mph unit. I believe these 140mph units are taken from 1979 units and recalibrated to work with the OEM setup for the 85mph unit.
When I purchased my speedo from RedLine, I had them set the milage before they sent it to me. With your's showing 46K miles, it's unlikely those are since the speedo was replaced. The previous owner likely had it set when the swap was done. Of course, he could have embellished on the number a little, ya know...say like dropping 20K miles. But you won't know know unless there is some documentation showing such. I just happened to take pictures, as well as have it on the onvoice from RedLine that I had the mileage set to XXXXX miles.

 

[chgostout]

Hey thanks burglar and evolution!

The 140 mph speedo in the car has the blue sub numbers, but the corvette insignia in the face of it has elongated flag ends, and doesn't match the insignia in the tach (like the 2 insignias in evolutions pictures), so I don't know if that matters; Although it could mean that the switch of mine was done some time ago, which might lend some creedance to my being told it showed true mileage. If some of you guys are just now switching it out - the ones you're getting from redline have the faceplates matching - so that even the insignias match. But if mine were switched more recently - using a cheaper company who didn't bother to go to the detail of matching the insignia, then the guy could've told them to set it at 44.000, to make that mileage seem much more palatable than the actual mileage, which conceivably could even be in the hundreds of thousands of miles! And that's something i don't want to think about tooo strongly .... right now.

Anyway, thanks again you guys, .... and if anyone else could shed any more light on this ... I'd appreciate it!

 

[Bob Yates]

Corvette Craig.... make sure it has a speed sensor in back of the speedometer gauge. I changed to a 140 when I had an 81 C3. It was cool. I got mind from Eckler's. It wasn't at that good of price that you have. Good Luck !!!!!

 

[LEEJANDZ]

chgostout -- and if anyone else could shed any more light on this

I know this is an older thread... but I thought I would jump in.
First of all there are 79's with factory 85mph speedometers.
Secondly your PO could have replaced the old assembly with a brand new one that started at 0.
So you have at least what ever your odometer says now + whatever was on the old odometer.
That sounds like the most likely scenario.

My 175mph speedometer is on its way to replace my factory 85mph unit.
Once I get it Ill ship it over to JOHN @ redline and have him reset it to 0.
My current odometer reads 49522, but is that 149522 or 249522?

Who knows?

JASON *** BRAND NEW MAGNECOR WIRES FOR SALE!!! *** 1979 L-82

 

[chgostout]

Thanks for your response, Jason.
Since posting the thread I've learned that the motor in the car was rebuilt, and I'm going to assume the speedo was changed at that time. So, the motor has 49k miles on it, if Im right.

If the speedo was changed before the rebuild - it has even less miles on it. Nevertheless, I'm happy with the car, because the mechanic described the rebuild as having been a "good one" - done well & properly. And that's all I'm really concerned about.

He determined the car had also been a race car, in it's previous life, as their was telltale signs of it's old race numbers underneath it's current paint job, and their are other aspects of it's suspension, springs, and rear end, that had been "beefed" up for racing.

So, while it would be nice to know the exact & complete history of the car - knowing that it's in good shape mechanically - is all any of us are REALLY concerned about - isn't it? We can't change their past, but we can project their future.

Imagine the stories these cars could tell us, about their experiences - if THEY could talk!

 

[Daryllawman]

live it long, and live it FAST

 

[KANE]

...ARISE FROM THE DEAD, OLD THREAD!






Does anyone know what the RPO was for the 140mph speedometer?

Just curious as to what option/RPO allowed for the 140mph speedo versus the 85mph unit. It's my understanding that GM succumbed to the Feds in late '79 and the 85mph speedo became the law of the land- thus the option / requirement either removed the 140mph unit or simply disappeared.

Seems to me... the 140mph factory gauge cars also came with a tachometer that had the 500rpm indicator numbers too.

I debated on starting a new thread, but thought this old thread was as good as any to ask in.

Perhaps JohnZ will chime in...





FWIW... Redline is making up a custom set of gauges for me- 140mph unit with the correct 1982 crossed flags (but with blue km's like the previous years) and then a custom tachometer with a red line specific for my .465"/.488" cammed motor (5,200rpm yellow and 5,500rpm red line since my shift point is at 5,450rpm).

I'm working on a historically-accurate-yet-fantasy-build sheet that has my OEM RPOs but also includes "options" that I've added... like bored out TBs, cam, injectors, fuel pump, VAFPR, EBL, etc. Would be nice to understand what the RPO was for the cars that had the 140mph units so that I can include that in my fantasy build package.

 

[bill81vette]

there was no option for the 140 MPH speedo.
it was 85 and that was it.140's were aftermarket only....
sorry.....:ugh

 

[KANE]

there was no option for the 140 MPH speedo.
it was 85 and that was it.140's were aftermarket only....
sorry.....:ugh

Bill- yeah, that's where it gets really confusing.

Several sources I have read indicate the 140mph unit was a factory piece for 1978s and available up until mid/late 1979. I was looking for the RPO for those years.

1979 Chevy Corvette - Vette Magazine

https://books.google.com/books?id=o...0mph speedometer 1978 corvette option&f=false

Besides... it's not like a lack of an RPO used in 1978 or 1979 is stopping me at this point.

 

[bill81vette]

I'll look in the corvette black book,and see if there in there..