I'm a pacbrake dummy

[whited44]

Hey everybody. My 94 Tourmaster has a 250 cummins, allison 6 speed, and a pacbrake. I've tried to use is several times but it doesn't seem like it's working. It has a switch so I turn it on. Then I have noticed no deceleration. Is it because it has not slowed down to the pre selected gear in the tranny? What is the best way to use it? Thanks

[deandec]

The pacbrake should only engage when you release the throttle and at speeds above 30 mph.

The light on the dash indicates that the Pacbrake has received an electronic signal on my rig. At the same time you should feel deceleration.

I find it most noticeable and also irritating when driving on surface streets and therefore turn it off on those occasions.

It is quite effective on steep grades.

[bdpreece]

Or if it has never been lubed it may be stuck and not working at all.
See here for instructions Maintenance

[whited44]

Thanks fellas. I will check and make sure everything is lubed properly when I get it out of storage. I think the previous owner may have pulled the fuse because he said the manifold was warped. But from what I have read it mounts off of the turbo right?

[whited44]

Then does it matter what gear it is in? So I should feel it when I let off the throttle in 6th gear right?

[deandec]

The pacbrake does mount to the turbo in many installations.

It will function in the 4 higher gears for sure.

You should feel it in 6th gear but if on level ground it does not seem as noticeable to me. Try it uphill, in 6th gear, off the throttle, that should give lots of feedback.

Do the same test with the Pacbrake on and then off. The results should be different if it is working.

[RVNeophytes2]

Quote:

Originally Posted by whited44 ... I've tried to use is several times but it doesn't seem like it's working.

Several sources point to it needing to be exercised regularly, kept clean and lubed.

Plus, mine works all the way down to walking speed.

["007"]

Here is some information on PAC BRAKE.

More information on wiring, installation and maintenance.

[SlocanPaul]

There is a throttle switch or relay that may not be functioning as well. This activates the exhaust brake when you take your foot off the throttle.

[Gary RVRoamer]

You may not feel much in 6th gear - there is not a whole lot of braking power in high gear at moderate speeds- but you should feel something. Then as speed drops, the tranny should downshift, with progressively more braking in each gear.

[samert111]

Two problems I've had with my Pacbrake over the years was a broken wire on the E-brake activation switch mounted on the fuel pump linkage and then the exhaust pipe exiting the turbo cracked and was allowing the exhaust back pressure when the E-brake was applied to escape and rendering the E-brake ineffective. The crack was almost impossible to see due to a support clamp keeping the broken pipe in place.

Also, my E-brake is not tied into my Allison MD3060 transmission so it doesn't automatically start to downshift when applied and I like it that way and just manually downshift as needed to hold my speed down.

And yes, you should feel some braking in 6th gear but these E-brakes will not throw you forward in your seat when applied.

[grye]

Many manufacturers in the 1990s installed a foot switch on the floor at the left side of the steering column. If your MH has one, use your left foot to activate the Pac Brake. The brake will release when the service brakes are applied.

[whited44]

So i'm getting time to mess around with the exhaust brake. Where would the fuse be located for the switch? I looked where all my other fuses are and it's not in there. I know I don't have the foot switch, and I don't think I have a light saying that it is in use. I'm going to be hitting the WV turnpike in July and it'd be real nice if this thing is workin.

[Steve Ownby]

If you have a pushbutton shift pad then when the pac brake receives a signal to close the gear selected window will change to 2 or 3. Then means that the signal is going to the Pac Brake but it could still be not closing.

Pick a spot on a slight to moderate downgrade with rpm's down below 1500 in 6th with the Pac Brake switch on and lift your foot completely off the throttle. Look at the gear selected window and see what happens. If the gear down happens but you are still unsure if the brake is working then repeat this exercise but turn the brake switch off and when you take your foot off the throttle manually downshift to 2 or 3 and see if you detect any difference in deceleration.