Engine/Transmission (1994 - 1998) jacobs brake from 24v to a 12v

[BTighe]

i have the chance to pick up a jacobs e brake for cheap. the truck its on is a 99 and i am wondering what all i need to install this on my rig. both rigs have hx35 so i know it will bolt on. TIA

 

[HoleshotHolset]

Vacuum lines, mircoswitches, on/off switch for the cab, etc.



Don't forget that you need to install 60-pound exhaust valve springs in your 12-valve before using the exhaust brake. That's the biggest pain in the neck of the whole process, IMHO.



Matt

 

[Got Smoke?]

Vacuum lines, mircoswitches, on/off switch for the cab, etc.



Don't forget that you need to install 60-pound exhaust valve springs in your 12-valve before using the exhaust brake. That's the biggest pain in the neck of the whole process, IMHO.



Matt

I did the very same for my for my previous 97..... bought a pacbrake from Craig Severson (when the pulling bug REALLY bit him :-laf ) and his is a 99 I think and mine was a 97. I had to buy the mirco switch, vacume lines, and I also bought a wiring harness. DON'T buy the last one.



You can make this brake work on your truck without the mirco switch behind your accelerator. You can wire it to a toggle switch on the dash, or to a push/pull switch on your gear shift. Just buy the vacume line kit with the plastic fittings, and the vacume switch and you can wire the rest.



And yes you will have to have 60lb springs installed for the full braking effect.

 

[Joseph Donnelly]

If back pressure isn't too great, you can use the stock springs. You will get about 70% of the possible braking effort vs. how you could set it with the stiffer springs. Vendors of these brakes can tell you how to measure backpressure and adjust it.

 

[GAmes]

If you need install instructions and the exploded parts diagram/list let me know. I can scan them and send them to you.

 

[Andy Redmond]

I just took one the other way, from a 96 12V to a 24 v (2001).



A Cummins dist had warrantied the late model casting out/brake out and sold us the new in box harness for a song. I was just about to order the late model harness and vacuum assy.



The harness from the 96 is complete (used in excellent condition) and for sale with installation instructions (I can't give it too you it belongs to the customer). Send me a pm, if you want the price and the customer's digits. I have some 60lb springs too!



Good luck

Andy

 

[BTighe]

if i do get this i would do both intake and exhaust spring changed for a 4kgsk

 

[Got Smoke?]

if i do get this i would do both intake and exhaust spring changed for a 4kgsk

Exh. Brake = just Exh. Springs

4K GSK = All Springs..... don't want to float/drop a valve do ya?

 

[BTighe]

id like to try but for now my temps are high enough with no turbo upgrade.

would installing 60lb springs on the intake and exhaust valves have any negative effect if i dont have a gsk?

 

[GAmes]

would installing 60lb springs on the intake and exhaust valves have any negative effect if i dont have a gsk?

None that I've seen so far.