Do GN's have a reducer on the speedometer cable near trans?

[buickrob]

My 87 GN read 20% faster at the speedometer than it should. Say, if I'm driving 50 mph the speedometer says 60mph. Also if I drive 1 mile the odometer says I went 1.2 miles. I was told by someone I worked with that some GM cars had reducers on the speedocable right where the cable meets the speedo gears in the drivers side of the tranny. My car just has the cable going right to the "bullet" for the speedo gear.

The rear end ratio is the stock 3.42, the speedo gear in the trans is the correct blue gear so I think this reducer thing could be what I need. Anybody know about it? Thanks

 

[quick85]

wrong gear or wrong tires my friend, i've been under a bunch of tr's. never seen a gear reducer.

 

[WE4]

Nope.... and it will screw up the vss...

 

[buickrob]

I don't know what the heck it is then
I have the right gear, correct tires, and correct rear end ratio. Could it be the wrong trans?
also, isn't my vss already screwed up due to the fact that the car is reading 20% over?

 

[WE4]

Only time I have seen this is when someone bought that decal 145 mph speedo kit. Never do this. Always have the speedo recalibrated.

 

[rob85gn]

speedo

i know a place in town here that makes those reducers for speedos u need to know for sure how much u r off then they can make one they r made for mack trucks etc but work on cars i had them make one up a few years ago for my van if u want i can check my gn speedo was off i changed the gears in the tranny

 

[buickrob]

I think somebody screwed with my trans

 

[quick85]

bweavy should be able to get you the right gear or trans, pat

 

[buickrob]

thanks all!!!!

 

[buickrob]

is it possible that I have the wrong VSS in my car? I have a digital dash car, maybe I someone put in a VSS for a analog dash car. Would that do anything?

my turbolink confirms that what the dash is saying is also what the vss is putting out. That means the VSS is also reading 20% higher than it should. Think it could be bad?

 

[rob85gn]

speedo

r u sure that they are 343 gears and not 373`s what tire size are u running and is it the original tranny they are all things to throw your speedo off hope this helps

 

[buickrob]

Definitely has 3.42 gears, I checked the numbers on the ring gear and divided them like you're supposed to. It came out to 3.42s.

Tire size is still 215/65/15 so I know they are right.

Only thing left is tranny. I thought it could be VSS but I guess you are saying it wouldn't be (shows what I know )

This tranny sux

 

[rob85gn]

speedo

i had to change the gears in my tranny to get the speedo right it is a pain in the but cus u have to drop the pan but worth it if u want it right ask around there are a few people on here that have the gears that u need i have one extra set my self but bweavy would hook u up better good luck