I have a 115 speedo and found a trans am with a 155 speedo on it but its a m6. My t/a is a 94 and the other is a 95. Can i just switch the clusters without ahving to do any programing or madifications?

 

since when did any 4th gen v8 fbody come with a 115 speedo?? did you do a v6-v8 swap?

 

My 94Z conv. came with a 120mph speedo. Since it had S rated tires the speedo was limited to 108 mph as well. The swap should be striaght forward. You'll need to reprogram the CPU to erase the limiter.

 

That's weird. didn't know any came with less than a 150 speedo. Never seen one that wasn't a v6.

 

To answer your question, if you're were switching out your speedo from stock to one with more "mph" on it, then yes you would need to have some programming done. We have a 200mph speedo gauge that we've held constant GPs on. Everyone had to have the cluster reprogrammed in order compensate for the difference in speedo's. If not, then you will not be correctly gauging your speed. For example, say you went from stock to a 200mph speedo. If you never got your cluster re-programmed, then the new gauge would read something like 60mph where in fact you're travelling at 80 (arbitrarily speaking).

 

Can anyone verify this???

 

and i dont think theres 200mph guege clusters for the Lt1

 

It should plug and play 115 to 155..[stock speedos that is]
In a Z the 110 to 150 speedo swap is a plug and play..
The limiter would need programming out..
And a search will reveal why there are 110 and 150 speedos[simply put, it has to do with whether Z speed rated tires were on the car new or not]

 

That is right. We only have the layouts for the '98's and up.

 

My 1994 Z28 convertible came with a 110 mph speedometer. I removed it and installed a factory 150 mph cluster. It was 100% plug and play. It works perfectly.

I still have a speed limiter, so I still cannot go faster than 110, but that will be fixed soon enough.

 

Thanks, i was hoping to ge feed back from someone that had dont this. Thanks

 

"Calibration" is only required when changing gauge faces on the same gauge cluster. The computer sends the same signal to the different gauges, so you don't need calibration if you're just swapping clusters out. You could probably even get away with swapping out gauge faces and not using calibrations if you used a funky gear ratio in the ecm. So an LT1 could in theory have a 200 mph gauge set if you use the 97 cluster and get ahold of the 200 mph faces that are intended for LS1s, then multiply your diff gear ratio by 4/3 and "trick" the computer.

 

When I bought my car in late 94 the only one real requirement was that it have a six speed. Of all the dealers and cars I looked at the only one I found that was a 6speed was also the only one that I found with a 110 or 115 speedometer. I remember asking the "salesman" about it, and can't remember his response. However it only took about 20 or 30 minutes on the trip home to figure it all out. Imagine my disappointment when the damn thing cut of at 105. Upon immediate research I discovered that like said previously cars that were not equiped with z rated tires from the factory had the 115 speedo, and cut off at 105 or so. Of course I took care of the limiter long ago, however I have always been told that it was a "major deal" to swap to a 150 speedo. After reading this I believe I will go down the road and visit a friend who parts 4th gens out and see what I can pick one up for.

 

The only part that's a PIA about swaping speedo's is trying not to crack the top dash plate as you take it out. Other than that it's pretty easy.

 

Any car that is sold in the U.S. has to have a limiter based on the speed rating of the tire as set by the DOT. Since S rated tires are approved only to 108, that's as fast as it will let you go (otherwise there'd be lawsuits for blown up tires, even though there's not really any public roads you can go that fast on here in the US...). I'm not sure how they're doing it now, I've noticed a lot of cars coming out have 155 speed limiters, so it's possible the DOT said all Z rated tires are now approved for a max of 155, and you've got to send out your cars with W or Y rated tires if you want to get around it now. I guess what I'm trying to say is that since you probably have Z rated tires or something like that on your car, originally that limiter served to keep the tires from overheating due to excessive speed and causing ply separation or other bad things to happen. Although it's funny that most tires actually fail from underinflation, not overheating...