Jake Brake Install

richard5933 · April 03, 2019, 12:19:12 PM

Just an update to my long-planned Jake install...

Bus is currently at Interstate Power Systems near Milwaukee in the care of one of their old-timers who's got decades of experience with buses (Jack).

So far things are progressing well. The Jakes looked good when I got the parts, but a full tune-up was done on them hoping to eliminate as many problems as possible. No way to know how long since the last tune-up. Jack says that he did an engine tune up after the initial install, and that only one of the injectors was out of spec and only by a tiny amount. Not surprising with only 47K on the odometer, but comforting to know nonetheless. I believe that he's doing the install strictly by-the-book regarding specs for the Jake settings. Other than this, the engine is bone stock.

I did as much prep work myself as I felt comfortable doing - electrical components installed in driver's electrical panel, installed tailgate bump, etc. but I left the engine internals to someone with the experience to get it right.

Looking forward to hitting the highway soon to give the Jakes a test. I'll report back once I have the bus again.

luvrbus · April 03, 2019, 12:42:05 PM

Pay attention and check the difference in oil consumption when you start using the Jakes it will use more

Geoff · April 03, 2019, 12:51:12 PM

If "Jack" sets the Jakes to book specs, the most you are going to gain is a little "flutter" in your exhaust noise and not much engine braking.

richard5933 · April 03, 2019, 01:20:32 PM

I'm going to let Jack do his thing on the Jakes for now. He set the Jakes on our 4106 a couple of years ago, and they did a pretty decent job of slowing things down. They didn't put us through the windshield, but they clearly were braking.

If needed, I can always have things tweaked down the road.

chessie4905 · April 03, 2019, 08:21:42 PM

I'm still waiting for Cliff to report back on how much piston to valve clearance there is on an 8V-71 at tdc. I mentioned on having Scott Crosby check it when he rebuilt a guy's 8V-71, but apparently he wasn't interested in checking.

TomC · April 04, 2019, 08:38:03 AM

Don Fairchild in Bakersfield set my Jakes. Coming down 6% grade of I-5 Grapevine, I have to switch between low and high to keep from slowing down too much. Properly adjusted, the Jakes are very affective.

With the higher valve covers, I couldn't shut my engine cover door. I simply removed the door cover and let the valve cover be exposed. Good Luck, TomC

luvrbus · April 04, 2019, 09:51:32 AM

Quote from: TomC on April 04, 2019, 08:38:03 AM
Don Fairchild in Bakersfield set my Jakes. Coming down 6% grade of I-5 Grapevine, I have to switch between low and high to keep from slowing down too much. Properly adjusted, the Jakes are very affective.

With the higher valve covers, I couldn't shut my engine cover door. I simply removed the door cover and let the valve cover be exposed. Good Luck, TomC

Your jakes are set om .55 that is what Don sets Jakes on plus you have transit gears not highway gears (3:73) he won't get the braking you do TomC.. Richard will be fine in in 1st,2nd and 3rd he just won't have much in 4th gear

richard5933 · April 04, 2019, 01:40:26 PM

Side benefit of this project - shop pointed out that the fuel pump on the 8V71 was leaking. Can only imagine that this would have gotten worse before it got better. Sometimes having extra eyes on the bus can be a good thing. I saw the moisture and assumed that the engine was doing its typical Detroit Diesel oozing.

muldoonman · April 04, 2019, 01:46:46 PM

Quote from: Geoff on April 03, 2019, 12:51:12 PM
If "Jack" sets the Jakes to book specs, the most you are going to gain is a little "flutter" in your exhaust noise and not much engine braking.

I guess your use to getting thrown through the window after hitting them.

For 9 years, I have used mine all the time, or since I've owned my bus. "8V92TA" Mine didn't work 3 days ago (1st time) heading upstate Texas. Noticed a huge difference in braking without. When they work, You will use a lot less brakes. Found a breaker under drivers area tripped and hope that will get them back online. You won't be sorry you put them on.

Geoff · April 04, 2019, 02:13:53 PM

Yup, I had to put an LED flashing red light in the center of my engine tailgate that reads "JAKES ON" so trucks don't run into me.

Quoteauthor=muldoonman link=topic=33888.msg388176#msg388176 date=1554410806]
I guess your use to getting thrown through the window after hitting them. For 9 years, I have used mine all the time, or since I've owned my bus. "8V92TA" Mine didn't work 3 days ago (1st time) heading upstate Texas. Noticed a huge difference in braking without. When they work, You will use a lot less brakes. Found a breaker under drivers area tripped and hope that will get them back online. You won't be sorry you put them on.

richard5933 · April 04, 2019, 02:28:38 PM

Quote from: Geoff on April 04, 2019, 02:13:53 PM

Yup, I had to put an LED flashing red light in the center of my engine tailgate that reads "JAKES ON" so trucks don't run into me.

We had the brake light discussion on an earlier thread, but here's where I ended with it...

They are installing them without tying into the brake light circuit. If the Jakes have the fair-to-midland effect on braking that others are talking about, then I'll probably have the Jakes engaged all the way down the larger hills. That's really why I wanted them, for the long downhill grades.

However, if I find that they are engaging more like service brakes and slowing things down quite considerably, I can always add the wiring to connect the Jake circuit with the brake light relay so it triggers the brake lights.

Or, I can do like Geoff and add a third (centered) brake light which is triggered by the Jakes and leave my regular brake lights to function only with the service brakes.

For now, the Jakes won't activate the brake light though.

lostagain · April 04, 2019, 04:52:47 PM

Brake lights are for service brakes, not for engine brakes. Jakes will slow you down considerably when driving an empty semi, but not enough to justify activating a brake light. I think a brake light that comes on with the engine brake would make you look like an idiot with your left foot on the brake pedal.

JC

chessie4905 · April 04, 2019, 05:35:16 PM

Put a flip up flag on the roof.😂

Geoff · April 04, 2019, 05:42:22 PM

Quote from: lostagain on April 04, 2019, 04:52:47 PM
Brake lights are for service brakes, not for engine brakes. Jakes will slow you down considerably when driving an empty semi, but not enough to justify activating a brake light. I think a brake light that comes on with the engine brake would make you look like an idiot with your left foot on the brake pedal.

JC

Think what you want, but CA was (or is) thinking to make it a law and they are in lockstep with DOT. My method is a rear center light that does not activate the brake lights.

richard5933 · April 04, 2019, 05:46:00 PM

The GM wiring diagram for our bus has a page for the optional Jake brakes. Even back in 1974 the wiring diagram showed the brake lights being activated by the Jakes.

The guys at the shop doing the work agreed that it's probably best to not activate brake lights with the Jakes, as was mentioned earlier it would look like I'm going down the entire grade with my foot on the brakes. No one would really know when I used the service brakes.