BCM Community
Bus Discussion => Bus Topics ( click here for quick start! ) => Topic started by: richard5933 on 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.
-
Pay attention and check the difference in oil consumption when you start using the Jakes it will use more
-
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'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.
-
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.
-
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
-
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
-
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.
-
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. ;D 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.
-
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.
author=muldoonman link=topic=33888.msg388176#msg388176 date=1554410806]
I guess your use to getting thrown through the window after hitting them. ;D 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.
-
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.
-
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
-
Put a flip up flag on the roof.😂
-
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.
-
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.
-
I give up.
-
It's a option DOT Standard 108 for Jakes or a retarder,the school buses here the brake lights activate the Jakes and they drop out at 15mph
-
New coaches came with brake light jake activation since the late '90's. We simply pulled the breaker on that circuit.
-
I give up.
Not sure why - yours is the option I liked the best. If the Jakes are more than marginally effective adding the third LED brake light seems like the most logical way to go.
I want to see how things go before doing the mod though.
-
My DL3 is a 1998 and factory setup on the jakes does not activate the brake lights. Most stick and staple pushers I have come across with jakes usually activate the brake lights. Clifford how is your DL3 setup?
-
The Jakes or the retarder does not activate my brakes lighs on my DL3.I doubt it will ever become a DOT rule
-
It seems to me that the intention of brake lights is to signal to a following driver that you are slowing down regardless of HOW you are doing it-service brakes, jake brakes or dragging your foot. I don't have jakes(unfortunately) but I think they slow you down.
-
It seems to me that the intention of brake lights is to signal to a following driver that you are slowing down regardless of HOW you are doing it-service brakes, jake brakes or dragging your foot. I don't have jakes(unfortunately) but I think they slow you down.
You have 4 way flasher if you slow down to much
that is the purpose of those ,the millions of trucks on the road you never see a 3rd light warning for engine brake use
-
It seems to me that the intention of brake lights is to signal to a following driver that you are slowing down regardless of HOW you are doing it-service brakes, jake brakes or dragging your foot. I don't have jakes(unfortunately) but I think they slow you down.
Guess it all depends on how strongly the braking action is from the Jakes once they're installed and I get to give them a test on the road. If I find that they are providing a decent braking action and really causing us to slow down, I'll probably wire the brake light circuit to the Jakes. However, if I find that what they are really doing is keeping us from gaining speed or only slightly slowing us down it might be more confusing to drivers behind me. Imagine a 5 or 6 mile downhill grade where the Jakes are just helping us maintain current speed? They'd be activated all the way down the hill and would keep the brake lights on the whole time. Guess I'll know more of which way to go once things are completed and installed.
Right now, it's just a waiting game till things are done. Ran into a slight hiccup, as we're waiting for the fuel pump to arrive, and that has to be done before the Jake install can be completed. Apparently a cooling line had to be removed to gain access to the fuel pump, which necessitated draining the coolant. The mechanic didn't close the valves on the bulkhead, so he drained all 23 gallons and has to re-bleed the system. Not a big problem but additional time (that I'm not paying for).
Always seems to be something to slow things down. Glad that I brought the bus to them early in the season so I'm not chomping at the bit to get on the road.
-
you can always just apply the brake peddle just enough so to turn on the brake lights if you want to ? that's what I do if I see some dumb @$# behind me cumming up fast
dave
-
that's what I do if I see some dumb @$# behind me cumming up fast
dave
Sounds a little risque.
-
Uhh...who's going to follow you? Ones that cannot pass? Trucks already know you are slowing while going down a grade, just like 99% of the other trucks on the road.
-
the millions of trucks on the road you never see a 3rd light warning for engine brake use
In this country we have cattle haulers deluxe, followed one the other day he never touched the brakes once to turn off the highway from 65 mph.
But then here a town of 8000 is a big town so all drivers wave at each other.... In a big city I can see why you would want it.
Just a matter of your personal opinion. There are ups and downs of both ways... Same as everything ;)
-
confuse them.
https://www.youtube.com/watch?v=j_x7wpzwKMM
-
My 91 lights um up when activated. Usually if they're on, I'm slowing down. Hence, brake lights. Don't run into me.
-
Would it be logical (maybe legal as well), to have a amber light in the rear that comes on with the Jacobs brake? That way there would a two stage warning of braking action.
-
Seems like this debate has been going on for decades - the book shows the brake lights being tied into the Jake brakes, but apparently few people actually starting doing that until recently when Jakes began performing more like the service brakes. At least that's what I'm reading online and gathering from the 'old timers' at the shop.
Tying into the brake light circuit isn't that difficult, according to the wiring diagram. Apparently there is already an unused wire in the OEM harness to bring the 24v signal from the Jakes back to the driver's electrical compartment. A short wire in the engine bay brings the signal to this wire in the harness, and then another short wire in the driver's electrical panel connects to the stop light relay to activate the stop lights.
Only question I have is which of the two stop light relays in the driver's electrical panel is used? There are two, one is labeled in the book as 'stop light relay' and the other as 'DD-3 brake stop lamp relay'. I'm guessing that they are talking about the one labeled 'stop light relay', but the diagram in the wiring diagram doesn't at all match the layout of the relay itself. Guess it's time to pull out the multimeter.
If I find that the Jakes provide actual stopping power, I'll connect the stop lights. I might add a toggle switch so that I can turn them back off for those long steep downhill grades where the Jakes do nothing but prevent acceleration so as not to have people think I'm riding the brakes all the way down.
-
When you are using Jakes about every truck or bus is doing the same,the transmission in our Trek will hold the same speed coming down from Golden Valley to Laughlin and that is 6% for 12 miles.This has always been just a option and not required by any law for years do what makes you happy .The newer buses have it or don't have it, none around here in Valley have it on these 6 % grades lol and I haven't heard of any getting rear ended,FWIW when wired to the stop light when the 1 way diode on the buffer switch blows and they do the Jakes will activate everytime you apply the brakes
-
...FWIW when wired to the stop light when the 1 way diode on the buffer switch blows and they do the Jakes will activate everytime you apply the brakes
That's one thing I couldn't find in the wiring diagram - the diode.
My assumption is that something about going through the relay keeps the stop lamps from backing up into the Jake circuit and firing the Jakes. But, looking at the diagram I just don't see it. At whatever point the power feed from the Jakes hits the stop light circuit, there will also be power being fed from the regular stop lamp circuit.
Sounds like a diode belongs in that circuit somewhere.
UNLESS...
Perhaps the 'stop lamp relay' shown in the Jake wiring circuit is an additional one which is added specifically to allow the Jake's power feed to the stop lamps to remain totally separate from the one from the service brakes.
Thoughts?
-
That's one thing I couldn't find in the wiring diagram - the diode.
My assumption is that something about going through the relay keeps the stop lamps from backing up into the Jake circuit and firing the Jakes. But, looking at the diagram I just don't see it. At whatever point the power feed from the Jakes hits the stop light circuit, there will also be power being fed from the regular stop lamp circuit.
Sounds like a diode belongs in that circuit somewhere.
UNLESS...
Perhaps the 'stop lamp relay' shown in the Jake wiring circuit is an additional one which is added specifically to allow the Jake's power feed to the stop lamps to remain totally separate from the one from the service brakes.
Thoughts?
From the wiring diagram you can see that when the engine brake solenoids are energized it also power the stop relay(terminals 3&4) wich close the circuit (terminals 1&2) for the brake lamps. With that setup, you don't need a diode.
As for blown up diode, one could put two in series hoping that they would not blow at the same time, but then...when would you know that one is blown and that now you're at the same point as having only one... I guess it would be better to replace the diode with one having higher watts rating.
-
From the wiring diagram you can see that when the engine brake solenoids are energized it also power the stop relay(terminals 3&4) wich close the circuit (terminals 1&2) for the brake lamps. With that setup, you don't need a diode.
As for blown up diode, one could put two in series hoping that they would not blow at the same time, but then...when would you know that one is blown and that now you're at the same point as having only one... I guess it would be better to replace the diode with one having higher watts rating.
I understand how the Jakes make the brake lights turn on. What I don't get is what will keep the brake lights from triggering the Jakes?
If I'm connecting power from the Jakes to the same relay that the main brake light circuit uses, then wouldn't the brake lights be able to back feed into the Jakes without a diode? That's why I'm thinking that they intended for the relay in this circuit to be an additional one and not one of the relays already in the brake light circuit. The Jakes would trigger the new relay, which would then send power to the existing brake light relay (on the same terminal that the service brakes use to trigger the brake lights). By using the extra relay, the brake lights couldn't back feed. Or so I think...
-
" I understand how the Jakes make the brake lights turn on. What I don't get is what will keep the brake lights from triggering the Jakes?"
Turning Jake switch to off.
-
All buffer switches have a one way diode on the switch or built it the switch to prevent back feed ,even with the switch off if the diode goes bad it will activate the Jakes wired through the brake lights
-
" I understand how the Jakes make the brake lights turn on. What I don't get is what will keep the brake lights from triggering the Jakes?"
Turning Jake switch to off.
The connection shown in the wiring diagram between the Jakes and the brake lights is rearward of the Jake switch. Heck, it's even rearward of the buffer switch. Apply 24v to that junction point it's going to send power to the Jakes, bypassing everything forward of that point. That's why I'm assuming that the stop light relay shown in the diagram is a new one installed specifically to isolate the Jakes from the existing brake light circuit/relay.
-
Makes no difference if wired with a 1 way relay the buffer switch will have a 1 way diode on if you look, I have replace a 100 of those diodes over the years on the snap type buffer switches like you have.Years back Jake sold a small capacitor to mount on the master and they would blow that diode in heart beat
-
Makes no difference if wired with a 1 way relay the buffer switch will have a 1 way diode on if you look, I have replace a 100 of those diodes over the years on the snap type buffer switches like you have.Years back Jake sold a small capacitor to mount on the master and they would blow that diode in heart beat
I must be missing something - the wiring diagram from GMC shows the connection point between the Jakes & the brake lights to be between the buffer switch and the Jake solenoids. The buffer switch diode will not do anything to stop the Jakes from applying if the brake lights were to back feed 24v at the point they're indicating. I've circled it on this copy. With there being nothing to prevent the Jakes from being activated with voltage applied to this location, that's what has me thinking that the stop light relay itself must be the isolation point.
-
From Jake troubleshooting manual, the diode seem to be only for protection. I guess that diode was not blowing when it was installed whit a capacitor.
The brake relay is an added relay. There is one in the DDEC II front junction box on my Prevost XL.
No need for a diode with this relay, stop lamps current cannot backfeed thru open terminal 1 or 2, since they are isolated from terminal 3&4 wich are connected to jake brake solenoid.
-
From Jake troubleshooting manual, the diode seem to be only for protection. I guess that diode was not blowing when it was installed whit a capacitor.
The brake relay is an added relay. There is one in the DDEC II front junction box on my Prevost XL.
No need for a diode with this relay, stop lamps current cannot backfeed thru open terminal 1 or 2, since they are isolated from terminal 3&4 wich are connected to jake brake solenoid.
That makes sense - thanks.
-
The manual transmissions have a switch on the clutch too there is a 101 ways to wire Jakes ,DDEC's Jakes are wired through the ECM plus the buffer switch shown is a early electronic type not what Richard has he has the snap type
-
By snap type, do you mean this kind of switch ?
-
I still think a dedicated third, centered stop light strip is the best route if you want to warn other upcoming traffic that you have your Jake's on. Activating the regular brake lights is overkill; using your 4-ways is for slow speed climbing hills, not going down them; and my center light is not illegal.
https://www.ebay.com/itm/17-quot-High-Power-40LED-Red-Trailer-Truck-RV-Stop-Tail-Rear-Brake-Turn-ID-Light-Bar-/222651952160?txnId=2229079231012
-
Yep I think if you want a light the 3rd light is the way to go lol but Geoff 4 ways are slow vehicle coming or going not just up.I am trying to help another guy where they didn't use a buffer switch with the fast idle and his system works off the transmission presuure so many ways to wire a Jake
-
Looking at EV that have regenerative braking, from Prius to leaf to tesla, rear brake lights may light up depending on the conditions. For example, Prius and Leaf have somewhat weak regen capability so the vehicle is not slowed significantly when the regen is working thus no rear brake light.
The Tesla has far stronger braking capability and does enable rear brake lights depending on the degree of braking generated by the regen. Following is a quote that describes it better.
"Unless the Model 3 is very different, Tesla vehicles automatically turn on brake lights when regenerative braking passes a certain threshold of deceleration. In practice, this seems to happen on my Model S when I’m slowing from moderate speeds (40 mph ish?) to about 4 mph. Below 4 mph, there is no regen braking. If I’m going at highway speeds, I don’t usually see the brake lights come on from regen, as the actual decrease in my speed is more gradual and doesn’t seem to reach the car’s threshold."
Personally, it seems excessive for rear brake lights to be connected to the Jakes.
-
Easy-peezy...
All we need is to install a decelerometer and connect it into the brake light circuit. Wouldn't matter the reason, as long as we're slowing down at a rate above the setpoint the lights come one. No problem.
-
LOL now we pole vaulting over a piss ant bed
-
Easy-peezy... Up
All we need is to install a decelerometer and connect it into the brake light circuit. Wouldn't matter the reason, as long as we're slowing down at a rate above the setpoint the lights come one. No problem.
That works for more than Jakes! Just think if you fell asleep and hit an overpass abutment, your brake lights would come on even if you were dead!
-
Yep but you wouldn't know it........ :o
-
Whatever you do, the point is alerting the following driver.
4 miles of steady downhill brake lights on does NOT make friends...
And as you round the next bend, traffic is stopped, so you have to go deep into the service brakes... and nothing on the rear changes it's display...
In the transit/regional market, it is popular to have the retarder/jake activate a separate set of amber lights when engaged, and the brake lights stay reserved for service brake display.
Unorthodox lighting may be used against you by a savvy lawyer.
Stick to what is common?
Happy coaching!
Buswarrior
-
Yep but you wouldn't know it........ :o
Why would you need to know? This is all about the traffic behind you! A last saving grace might give you the ticket to heaven after a dubious life.
-
For many years I have had a set of amber lights come on when the Jake is working. I like the idea that there is some kind of warning that I am slowing. If I apply the service brake of course the brake lights come on.
-
4 miles of steady downhill brake lights on does NOT make friends...And as you round the next bend, traffic is stopped, so you have to go deep into the service brakes... and nothing on the rear changes it's display...
@bw - Perfect logic why not to connect Jakes to rear brakes. Not too smart to void the primary purpose of a rear brake light!
Adding the decelerate detection logic to a Jake-rear brake light would only light up when bus was truly slowing down.
-
Jake install is complete and has been tested. I wasn't there for the road test, but the mechanic tells me that I'll be impressed. A few delays along the way, but it basically went as planned. As close to the book as possible, other than the brake lights.
-
yep do it by the book is my way also,amazing that engine still has the original old style heads
-
yep do it by the book is my way also,amazing that engine still has the original old style heads
I'd guess it is the first time the valve covers have been removed.
-
!974 was the last year those heads were used and at a rebuild at Detroit they tossed those and replaced with the newer style lol 45 years of service is not too shabby
-
!974 was the last year those heads were used and at a rebuild at Detroit they tossed those and replaced with the newer style lol 45 years of service is not too shabby
What difference is there between these heads and the newer ones?
-
What difference is there between these heads and the newer ones?
the new style have larger water jackets,2 lbs more metal and easier hookups for the water cooled manifolds in marine use those heads were the pits, they will not withstand much heat in any application
-
Guess that means I'd better keep a close eye on the temp gauge...
Does using the Jakes build engine heat?
-
Does using the Jakes build engine heat?
No fire in the cylinder...
Happy coaching!
Buswarrior
-
That's ok. When you crack them on a long grade out west in the summer@ +100° without a good mister system, you can upgrade to the newer style.
-
Yes jake use does produce heat, but not near as much as an engine under load. When the jakes are operating you still get heat from friction and compressed air. Compare temps running down the same hill with and without jakes on and you will find the engine cools down much faster when the jakes are off.
-
How can Jakes make the engine run hotter than just coasting? Jakes prevent combustion, coasting means you still are firing each cylinder.
-
If I understand correctly, the Jakes turn the engine into a big air compressor. Air compressors get hot when running. Got to be less heat than when firing, but still more heat than coasting.
-
Physics.
Compressing a gas (air) will raise its temperature.
Also how you get compression ignition.
Happy coaching!
Buswarrior
-
I was talking about CLIMBING a hill, not descending one. Although I can see where some may be confused.
-
You Guys are gonna make Cliff get out his pole vaulting stick again. ::)
-
After a 45-minute drive home from the shop, I can say that the Jakes work. Not 'through the windshield' work, but they definitely provide braking action. On flat ground obviously they are more pronounced, but on a downgrade they certainly help hold speed.
Only problem with the install I noticed is that the valve cover rubs the bump, but it was easily fixed. The valve covers I was able to get had breathers on top of them, which were pulled and replaced with the DD blank plate/gasket. They sit flat, but do stick up about 3/8" higher than the surrounding vavle cover. To remedy things, I just adjusted the bumps stops and striker plates on the engine bay tailgate so that it doesn't close quite as far. From two feet away it's not possible to tell it's not sitting where it was before.