Speedometer
Thread Starter
|
Freshman User
Joined: Jan 2012
Posts: 44
Likes: 0
Speedometer
Have a 1991 f150 with a 302 and 4 wheel drive. Noticed the other day while doing around 60 65 that the speedometer was reading around 80. It has always been around 5 miles or so off but not sure why its that far off now. Anyone have any ideas?
Tuned
Joined: Aug 2004
Posts: 269
Likes: 0
the faster you go, the more mph you will be off. it is off by a percentage, not by a set mph.
i'm guessing it if off becuase you have changed gear ratios, or are running a tire with a height different than stock, or a combination of the two?
i'm guessing it if off becuase you have changed gear ratios, or are running a tire with a height different than stock, or a combination of the two?
Thread Starter
|
Freshman User
Joined: Jan 2012
Posts: 44
Likes: 0
Yes the tires are slightly oversized. 32x11.5. This was a odd incident as I tend to drive this truck on a regular basis. I dont know what caused it to read that high of a speed. I can run what the speedometer says is 70 and am right around 65, but that morning the speedometer was pegged over as far as it could go. I pulled the cable out of the transfer case and kinda gave it a quick look but was thinking that even if the gear had broke it wouldnt cause it read faster?...idk The gear should be the stock gear though as I havent ever changed it
Postmaster
Joined: Aug 2005
Posts: 4,728
Likes: 8
From: Cleveland, TN
Well, something is wrong, the larger tires "should" make the speedometer run slower than actual speed.. not faster.. Has the transmission been changed? If so it might have a gear for a different gear ratio rear end.
Thread Starter
|
Freshman User
Joined: Jan 2012
Posts: 44
Likes: 0
Yes the transmission was changed about 3 or 4 years ago..I had it rebuilt. I havent had any issues with it over the time period since. Is it possible for a mechanical speedometer to just fail?...the altenator gauge actually had the cap fall off of it and dosent work anymore but seeing as the speedometer has a cable I dont know if it could just fail? moving parts getting wore out?
Thread
Thread Starter
Forum
Replies
Last Post
Mr7.50headsup
1973 - 1979 F-100 & Larger F-Series Trucks
9
Feb 20, 2014 11:22 PM
jpjahn
1980 - 1986 Bullnose F100, F150 & Larger F-Series Trucks
62
Jan 17, 2006 11:26 AM
