tach sensor question

[Jan-78FJ40]

How does a tach sensor on a 3b or 2H EXACTLY work? Does it count teeth of the flywheel, or does it count how fast the teeth fly by?
In other words, would a tach sensor of a 3B give me the wrong rpm readings in a 2H?
thank you,
Jan

 

[brisveganbj42]

i dont think a tach sensor from a 3b would fit in a 2h...

reason i know is i attempted teh reverse.. my 3b tacho sensor is cactus so i tried to source a replacement from the wreckers.. all they had was one for a 2h and when i tried to install it it was too long compared to the 3b sensor...

I would be curious to know if there is a way to fix the 3b sensor seeing a replacement is so hard to find here in OZ.


from what i could tell.. 3b tacho sensor is flat an wide, and 2h is long and thinner..
sorry i dont have exact dimensions or pix cos this was a while ago..

HTH.

 

[Jan-78FJ40]

i dont think a tach sensor from a 3b would fit in a 2h...

reason i know is i attempted teh reverse.. my 3b tacho sensor is cactus so i tried to source a replacement from the wreckers.. all they had was one for a 2h and when i tried to install it it was too long compared to the 3b sensor...

I would be curious to know if there is a way to fix the 3b sensor seeing a replacement is so hard to find here in OZ.


from what i could tell.. 3b tacho sensor is flat an wide, and 2h is long and thinner..
sorry i dont have exact dimensions or pix cos this was a while ago..

HTH.

It must depend on the year. The 3B sensor fit exactly, it had the same length. It came from a 1985 BJ70, and fit into a 1984 HJ60.
Jan

 

[Tapage]

where is the exact place for this sensor . ?

 

[Jan-78FJ40]

it's on the flywheel housing, on the driver's side. it sticks into the housing close to the flywheel, and 2 wires hook into the harness from it. On the pic you can see the hole where the sensor screws into on the right.
jan

 

[Tapage]

Thank you very much Jan .. it will be very apreciated .. !

 

[Greg_B]

How does a tach sensor on a 3b or 2H EXACTLY work? Does it count teeth of the flywheel, or does it count how fast the teeth fly by?
In other words, would a tach sensor of a 3B give me the wrong rpm readings in a 2H?
thank you,
Jan

Punch the part number 83180-60040 into EPC. Good for lots of applications, including 1984 and newer BJ60's, and 1980-87 HJ6*'s. I would "guess" from EPC it would work, but till ya try...

hth's

gb

 

[Jan-78FJ40]

Punch the part number 83180-60040 into EPC. Good for lots of applications, including 1984 and newer BJ60's, and 1980-87 HJ6*'s. I would "guess" from EPC it would work, but till ya try...

hth's

gb

Thank you Greg,

I actually have the sensor in the truck, and it srews right in. It also gives an rpm reading, I am just not sure if it is the correct one. If the sensor counts teeth, and the HJ60 flywheel is bigger/has more teeth, than I would get a wrong reading.

Here is the background: I have a BJ70 on 33 tires, with 3.73 gears, and at 100km/h it runs about 2500 rpm (all approximately).
The HJ60 supposedly has 4.11 gears, is also on 33 inch tires, but at 100km/h it shows 3000rpm (with a BJ70 tach sensor), which seems high to me.
That's why I am wondering.
Thanks,
Jan

 

[Greg_B]

Thank you Greg,

I actually have the sensor in the truck, and it srews right in. It also gives an rpm reading, I am just not sure if it is the correct one. If the sensor counts teeth, and the HJ60 flywheel is bigger/has more teeth, than I would get a wrong reading.

Here is the background: I have a BJ70 on 33 tires, with 3.73 gears, and at 100km/h it runs about 2500 rpm (all approximately).
The HJ60 supposedly has 4.11 gears, is also on 33 inch tires, but at 100km/h it shows 3000rpm (with a BJ70 tach sensor), which seems high to me.
That's why I am wondering.
Thanks,
Jan

If it's working, check your actual speed with GPS, then have an adapter made to correct the ratio from the t-case to the speedo cable...

gb

 

[Jan-78FJ40]

If it's working, check your actual speed with GPS, then have an adapter made to correct the ratio from the t-case to the speedo cable...

gb

sure, that would fix the altered speedo reading, but not the rpm, right?

thanks,
Jan

 

[Greg_B]

sure, that would fix the altered speedo reading, but not the rpm, right?

thanks,
Jan

Ya...brain fade there on my part.

I don't see why EPC would list that one part for so many crossovers if it was not able to work on all the flywheels though, and any adjustment made elseware...unless I am missing something. Is your tach gauge cluster from another HJ series truck, or?

hth's

gb

 

[Jan-78FJ40]

Yes, I agree. thank you,
Jan

 

[curious1]

The hall effect sensor pick up that goes on the bell housing is the same on all models. The tach unit at the guage comes pre set for the car it was in. If it is reading wrong at the guage, you can have a potentiometer added so you can adjust it.

 

[tlcruiserman]

Jan,

Based on the gear ratio chart in the tech section of WCC I think everthing is correct and somewhere along the way the gears were changed to 4.56 gear on the 60 series. Here is the link, the numbers are a close match to support 4.56 gears on the HJ60

http://www.westcoastcruisers.org/techgearratios.html

Maybe we can lift up tha back and do the visual check of driveshaft to wheel spin.

Cheers,

Michael