speedo off by 15 mph

[CUMMINS KID]

ok i know it's not a big deal buit it annoys me. i'v had this truck for ooohhhh 2 month's put 6,000 miles on her and it's annoying me to the point i dont care what it takes i want it fixed! 2so here is what she does
lets say in going 65 mph the speedo reads 80
i cant figure it out traced all the wires and everything look's good
thank you for your help Jason
p:s how do i figure out if i have a W250 OR A D250???

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1993 LE 250 4X4 AUTO 95,000
MILES. BED RACKS. ALL STOCK ... FOR NOW... .

 

[ETOBICOKE]

W is 4 wheel drive, D is 2 wheel drive. Would not suspect that your speedo is the problem, it uses a transducer, not a cable drive. I think the previos owner had larger wheels/tires and changed the drive ratio of the speedo or the axle ratio has been changed. You should be able to remedy the problem by changing the drive gear that runs the tranducer, it's located on the transmission tail shaft housing. Most dealers parts departments have a chart with the gear part numbers for the tire size and gear ratio you have, failing that try a speedo shop.

Neil #ad


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Neil Copeman 92 D250,LE,limited slip, 16cm turbo housing, Isspro gauges, factory tach option, Lear cap, DC crankdown tire carrier
Hadley air horns, Stealhorse leather seats, e-mail (home): bombedcummins@sympatico. ca

 

[David Phipps/Mike Hurd]

OK, changing stock tire size will affect speed on the head unit. But not to a great degree unless your running big mud boggers. Any speedo shop can get your speed correct. When I replaced my gettrash with the nv4500 It was off by 43mph. I got it reading correctly by a speedo shop in Orlando, Fl for 85. 00. On the w vs. d I thought W was for 4x4 and D = 2 wheel drive But I'm sure someone will correct me on this. Mike

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http://hometown. aol.com/hotshothauler/myhomepage/business.html 2000, Air brakes on truck & trailer. 179,000 miles todate. DOT custom built sleeper unit. pulling a 40' G/N flatbed
2000 FL-70 Pulling a 48' low boy.

 

[unclebilly]

Perhaps your rear gears have been changed from 3. 54s to 4. 11s - that would nock it out by ~15%.

Scott.

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91. 5 CTD 4X4, 5" Stacks, Tweaked Pump, 33" Boots (in the summer), Unlimited Slip,
<P><B><A Big, Bad Dodge

 

[Crash_AF]

The previous owner of my rig changed the transmission out and forgot to make sure he had the right speedo gear in it. Now mine is off by . 7 miles per hour. (MM to MM it clocks 1. 7 miles) which is more than 15% I think. I believe the donor rig had 3. 55s in the rear while mine has 4. 11s.

Someone also stole the speed transducer off the transmission while it was in front of his house, so I bought a new one and installed it... Imagine my surprise when I was accellerating down the interstate and the speedo passed 100 MPH to bury against the odo reset... #ad


I guess I've just got a REALLY fast truck... #ad


Joe

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Joe Hinson, 93 D-350
Stock, 3in straight pipe - For now

 

[CUMMINS KID]

ALRIGHT THE REAR END AND FRONT END ARE BOTH 3. 73 S OR 3. 74 WHATEVER THEY ARE THEY ARE STOCK THE transmission IS NEW WHEN I GOT IT IT LOOKED ABOUT A WEEK OLD NO DIRT NOTHING BOLT'S STILL SCRATCHED W/O RUST YET LEAD'S ME TO BLEAVE IT'S NEW... . ALSO ANOTHER? HOW MUTCH HP AND FT LBS COULD I PUT THROUGH THAT STOCK transmission??? WANT MUTCH ABOUT 750 FT LBS WHEN IM DONE AND WHATS THE MODLE transmission IN THIS THING????

THANK YOU FOR ALL YOUR HELP JASON

 

[unclebilly]

THAD TRINNY ID A GETRAG A360 IF'N ID'S DA STOCK 'UN.

I BET SINCE THE transmission WAS SWAPPED, THE WRONG DRIVE GEAR IS IN THERE (THE ONE FOR 4. 11 GEARS).

IF YOU WANT TO PUT 750 FT-LBS THRU A GETRAG, MAKE FRIENDS WITH MIKE AT STANDARD TRANSMISSION, YOU'LL BE TALKING TO HIM ALOT.

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91. 5 CTD 4X4, 5" Stacks, Tweaked Pump, 33" Boots (in the summer), Unlimited Slip,
<P><B><A Big, Bad Dodge

 

[Paul Herioux]

From the amount your off it sounds like you might be missing the speedo drive adapter. It would screw onto the t/case, the speed/distance sensor screws onto the adapter and the speedo cable screws into the sensor. The adapters are kind of fragile and expensive, it may have fallen apart in past and not been replaced but by-passed instead.
Hope this helps.

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89 w250, 47rh trans, cleaned up exhaust, Dynomax bullet muffer, 3" lift

 

[Bob Beauchaine]

CUMMINS KID
There is a speedo shop in Portland OR that can fix you up with an adapter to correct your speedo. You just tell them how far off you are and they will build you an adapter for under $50. It goes between drive gear and the sensor. If you decide to go this route email me and I will dig out their number. They set mine right when I put in the NV4500HD
Happy Trails

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1993 250 4X2 - Banks Power Pack, BD Power Injectors, K&N Air Filter, 6 gauges and tweaked pump. 27lbs boost unloaded.
Horton fan & NV4500 5 speed.

 

[paccool]

OK guys, I just changed my speedo gear and there are a couple of things you need to know.

Mine was reading 20% slow when I changed the rear ratio back to 3. 54. Figured the easiest way was to go to a dealer and have them get me a gear. After 2 tries and 2 wrong gears, I went back and we pulled the pictures up on the screen. They didn't even show the one for my truck. I went to a speedo shop and told them what happened, that the new gear was about twice as long as the existing and he said "you need the short gear for that truck". He walked over to a bin without looking at a book and pulled out the right one.

There is one bolt with a clamp bar that holds the housing in place. When changing, you will note that the new gears are different size as well as different tooth count than the old and there are some tooth count numbers on the housing along with a mark on the tail piece. the speedo housing needs to be rotated to match up the different gear sizes. This probably sounds confusing but look at the housing before you pull it off and you will see what I'm talking about.

There is also an O-ring were the speedo housing slips into the tail piece. I would suggest this be changed while things are apart.

One last thing - the above info is for my 93 with an auto. I don't know if the manuals are the same.

Hope this helps! #ad


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Stan
93 2WD extended cab, Banks Power Pack, K&N air filter, PW Injectors,rebuilt and tweaked pump, auto w/3. 54 rear with limited slip, US Gear Exhaust Brake, 3-1/2" Exhaust, 5K air bags, Boost/Pyro/Tach Gauges, Green/Silver, new 40-20-40 bucket seats, 151K

 

[Crash_AF]

Yepper, it's the same for almost everything. My 89 Comanche had the same small round adapter on it when it was 2 wheel drive, the Getrag has the same one, as do all modern NP transfer cases and the NV4500. (at least that I've found)

Later,
Joe

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Joe Hinson, 93 D-350
Stock, 3in straight pipe - For now

 

[paccool]

The 93's have an electronic sender at the speedo gear. I think the 92's and earlier have a cable. The manual is not a lot of help in this area.

Stan

 

[unclebilly]

My 91. 5 has an electric setup - no cable

 

[paccool]

unclebilly,

thats what I meant when I said the book isn't a lot of help. It says 92 and earlier. Oh well, this is probably why the parts house couldn't find the right part!

Just trying to help a fellow first genner

Stan