1985 gmc brigadier speedometer not working

[soapstoneguy]

Hey just picked up that truck. Noticed on the way home the speedo doesn't work. Any tips or tricks to get it running or places to get one?
Also, guy said it takes 3 batteries but there were only 2 in it and didn't look like there were other cables to tie a third in...any advice would be appreciated. Started up with 2 in it and didn't seem to have any issues, drove it home about 40min away.

Thanks in advance!
Anything to watch out for with these or tips and tricks from experienced owners?
I believe it has a cummins big cam in it but not sure which yet. Need to steam clean it and crawl under it. Crazy thing is there doesn't seem to be a drop of oil coming out of it...other than the pto a tiny little bit.

 

[Shimmy1]

Speedo will be cable drive most likely, maybe the drive on the back of the trans is failed, that would be the easy fix. I didn't have much luck keeping speedos working on our old trucks. If the cable is broke, you can get new stuff to fix it. As far as the battery issue, you just put a third battery next to the other two, and hopefully, if it has stud post, just connect it up with short cables, pos to pos, neg to neg.

 

[skyking1]

If it has a 2 speed rear end then it has a speedo gearbox to allow for that.

 

[IceHole]

I'd be surprised if it DID work and was accurate.

Probably easier to use GPS at this point.

 

[soapstoneguy]

So it does take 3 batteries? Thank you for the info, I'll crawl under and take a look today and see what's going on. Thanks for pointing me in the right direction!

Speedo will be cable drive most likely, maybe the drive on the back of the trans is failed, that would be the easy fix. I didn't have much luck keeping speedos working on our old trucks. If the cable is broke, you can get new stuff to fix it. As far as the battery issue, you just put a third battery next to the other two, and hopefully, if it has stud post, just connect it up with short cables, pos to pos, neg to neg.

 

[soapstoneguy]

What would you recommend for using gps?

 

[soapstoneguy]

I'd be surprised if it DID work and was accurate.

Probably easier to use GPS at this point.

What would you recommend for using gps?

 

[IceHole]

So it does take 3 batteries? Thank you for the info, I'll crawl under and take a look today and see what's going on. Thanks for pointing me in the right direction!

Takes however many you want to put and have room for. Have seen trucks with only 1 and some with 6

 

[soapstoneguy]

Takes however many you want to put and have room for. Have seen trucks with only 1 and some with 6

What would be the advantage of having 3 vs 2 if it started with 2 in it?

 

[Old Doug]

You should be able to look and see if it ever had 3 or if it just had 2. If it starts ok all the time I would stay with 2 . 3 will just make it turn over better when its cold.

 

[Truck Shop]

There are three types of speedometers that can be used, mechanical, electronic & GPS.
In many cases on trucks a ratio box is used at the transmission to increase or decrease
speedometer speed, several variables come into play such as tire size and final drive
gear ratio. The electronic is run off a sensor at transmission and uses dip switches on
the back of speedometer head to set speed using the same tire size/gear ratio to work
up settings using math to calibrate. The there is the GPS speedometer-real simple has
a sky aimed transmitter located outside of cab. Very accurate but does have a slight
delay as speed increases, but is quick to reset, easy to install. Link to speedo ratio box.
*

https://texasindustrialelectric.com/800_Series_Speedometer_Adapter.asp

 

[BC Placer gold]

There are three types of speedometers that can be used, mechanical, electronic & GPS.
In many cases on trucks a ratio box is used at the transmission to increase or decrease
speedometer speed, several variables come into play such as tire size and final drive
gear ratio. The electronic is run off a sensor at transmission and uses dip switches on
the back of speedometer head to set speed using the same tire size/gear ratio to work
up settings using math to calibrate. The there is the GPS speedometer-real simple has
a sky aimed transmitter located outside of cab. Very accurate but does have a slight
delay as speed increases, but is quick to reset, easy to install. Link to speedo ratio box.
*

https://texasindustrialelectric.com/800_Series_Speedometer_Adapter.asp

We put a gps unit in our Ford cab over, works really well, nice analog style. As you say there is a slight delay. It fit nicely in the factory housing.

 

[IceHole]

I normally use my phone

 

[Truck Shop]

CFR-393.82---Trucks and buses have to have a working speedometer.
same as.
CFR-393.81---A working horn.
*
A phone wouldn't look too well in case of a accident--has to hands free.

 

[soapstoneguy]

Thanks for all the information and replies, it really helps.

So crawling around under there after cleaning the old girl off, turns out it's a cummins lta10. Looks like it takes 10gal of oil and 2 oil filters yes?

 

[soapstoneguy]

Also, was going to drain the coolant and replace it. Anyone have any recommendations on which coolant they prefer for this or no?

 

[Truck Shop]

L10--10 gal sounds right and a full flow with by-pass filter, Just drain the coolant replace
with pinkish-red extended life coolant. 5109 for fuel filter-should be.

 

[skyking1]

Thanks for all the information and replies, it really helps.

So crawling around under there after cleaning the old girl off, turns out it's a cummins lta10. Looks like it takes 10gal of oil and 2 oil filters yes?

nice to not have to go it alone

 

[IceHole]

CFR-393.82---Trucks and buses have to have a working speedometer.
same as.
CFR-393.81---A working horn.
*
A phone wouldn't look too well in case of a accident--has to hands free.

Set the phone in a holder. Google maps. Done.

Reminds me I should fix the horn on one of my trucks

 

[IceHole]

L10--10 gal sounds right and a full flow with by-pass filter, Just drain the coolant replace
with pinkish-red extended life coolant. 5109 for fuel filter-should be.

I don't know any shop not running ELC these days