BJ74 Restoration and LHD Conversion has begun!

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I was able to get time to swap in 60 series speedo drive and driven gears in the 74 to compensate for the 33 inch tires. Cruiser dan got me the parts and simple directions. I didn't drain the transfer case, just pulled off the flange and seal and let it run in the drain pan out the flange. by the time i was ready to put the seal back in, it was about done draining. The seal held the rest in. Very straight foward.. Just topped off the fluid.

Dan said it would correct the speedo, so I will find out when I drive it next.

Thanks Dan


Well--that didn't work out very well :(

At 60 MPH on the GPS, 2200RPM, my speedo now reads 68 MPH! However, the odometer registered 50.3 KM, or 31.23 miles. GPS registered 33.9 miles. 9.5% under. I doubt if the GPS is off. So now I think the BJ70 speedo face is not such a great idea.

went in the wrong direction.
 
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Well--that didn't work out very well :(

At 60 MPH on the GPS, 2200RPM, my speedo now reads 68 MPH! However, the odometer registered 50.3 KM, or 31.23 miles. GPS registered 33.9 miles. 9.5% under. I doubt if the GPS is off. So now I think the BJ70 speedo face is not such a great idea.

went in the wrong direction.


I pulled the speedo gears back out. The ones Dan gave me were labeled 6 X 15-17. The one that was in there was 6 X 18. I put the OEM gears back in, and I am back down to the speedo reading 64 at 60 MPH. GPS registered 20 miles, Odometer registered 27.5 kM, or 17 miles
 
I discovered a long time ago that my GPS is not accurate When used as an odometer. Of coursr it will give accurate distances to the next corner when a destination is programmed but not if your trying to measure distances off the units life mileage counter
 
I discovered a long time ago that my GPS is not accurate When used as an odometer. Of coursr it will give accurate distances to the next corner when a destination is programmed but not if your trying to measure distances off the units life mileage counter

Yeah, the distance (Odometer) did not seem consistent. MPH was though
 
i did not know this ... the mileage higher or lower than odometer?
seems to be common practice to use the GPS as accurate measurement for fuel mileage. if incorrect then a lot of posted claims could be questionable.
interesting.
 
Your rear end ratio could be throwing the math off too. Drive teeth X gear ratio X tire revolutions per mile divided by @ 1000 = how many teeth.
I don't know the drive tooth number, but if the error is the speedo is being driven too fast, then a higher tooth count would yield a slower speedo. no expert here, but that's what I would try
 
74 stock is 4.11
is the GPS out enough to really matter? on a 1500 km actual trip, what would the GPS be out by?
 
74 stock is 4.11
is the GPS out enough to really matter? on a 1500 km actual trip, what would the GPS be out by?

Mine was off about 10%. With the new drive setup it is spot-on.
 
i did not know this ... the mileage higher or lower than odometer?
seems to be common practice to use the GPS as accurate measurement for fuel mileage. if incorrect then a lot of posted claims could be questionable.
interesting.
The firsy dr
Mine was off about 10%. With the new drive setup it is spot-on.

did you see the post? i put the gears in and it added 5mph to the reading. instead of the speedo reading 5mph high, it became 10 mph high
 
That doesn't make sense. With stock gears and 33 inch tires the speedo should have been reading SLOWER than the vehicle is actually traveling, not faster. I did not see the other posts but it sounds like the needle is not reading properly in relation to the mechanical drive. There is a magnetic cup that spins to move the needle. I presume you had to remove the needle when you changed the faces? Maybe something something happened when it went back togther.

Mine is running 65MPH/105KPH at 2400 RPM (edit in 5th gear). Indicated and GPS are within a mile or two of each other.
 
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Mine is running 65MPH/105KPH at 2400 RPM. Indicated and GPS are within a mile or two of each other.

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......... and this is on 33" tires?
 
I have heard those cups can be touchy. Maybe a speedo shop can check the indicated speed against the mechanical odometer and make them match. I bet right now the mechanical ODO is running slower than the indicated speed on the dial.
 
Mine is running 65MPH/105KPH at 2400 RPM. Indicated and GPS are within a mile or two of each other.

--------------------------------------------------------------------------
......... and this is on 33" tires?


Yes, 285/75/16 BFG KM2.
 
I have heard those cups can be touchy. Maybe a speedo shop can check the indicated speed against the mechanical odometer and make them match. I bet right now the mechanical ODO is running slower than the indicated speed on the dial.
yes---the odometer is running slower, with each of the different speedo gears. Those numbers are posted below
 
WITH THE NEW GEARS

At 60 MPH on the GPS, 2200RPM, my speedo now reads 68 MPH! However, the odometer registered 50.3 KM, or 31.23 miles. GPS registered 33.9 miles. 9.5% under. I doubt if the GPS is off. So now I think the BJ70 speedo face is not such a great idea.



I pulled the speedo gears back out. The ones Dan gave me were labeled 6 X 15-17. The one that was in there was 6 X 18. I put the OEM gears back in, and I am back down to the speedo reading 64 at 60 MPH. GPS registered 20 miles, Odometer registered 27.5 kM, or 17 miles
 
Then I would say it is a dial/cup issue.
 
Maybe one day i will dive into my speedo and try to solve the same mystery. With 32" tires my speedo reads about 6% higher than actual while the odo reads a few % low. Every once in a while I try to rationalize it but before I reach a conclusion I go have a beer. That seems to help...
 
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