BCM Community
Bus Discussion => Bus Topics ( click here for quick start! ) => Topic started by: Nick Badame Refrig/ACC on May 21, 2007, 05:39:57 AM
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Hi Members,
After my weekend venture to North Western PA, and being diverted off I-80 because of a bus accident.
I really got a wake up call on some very steep decents down mountains on Rt 322.....
Going up a mountain is no problem, the 8V92 flattens them out.. man, I had my heart in my mouth quite a few times
They have signs that say, Trucks 35 mph.. Yea, try keeping that speed with no Jakes and your brakes will be gone
in no time. I know I overheated my brakes a couple times. All in all, it's pretty scary wondering if your brakes will hold!
Question, What kinda job is it installing Jakes in my bus? "DD 8V92T HT-740"
Thanks in advance
Nick-
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I recall reading some posts about Jake brakes very recently and I thought someone (TomC maybe) saying that Jakes are not very effective on two stroke diesels.
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Hi Nick
I had jakes installed on my 6V-92, they work great as I live in British Columbia lots of grades. I got a used set from a wrecker for $800 and paid $800 to have them installed.
Gary
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Brian -
Whoever made that statement doesn't have a lot of "seat time" in a bus equipped with a two-stroke and a jake.
IIRC, his comments were about an 18-wheeler loaded to 80,000 lbs, a whole different scenario compared to a 30K bus.
Back in my charter driver days, I used to put 80K/year on buses with jakes, working CA, OR, NV, & AZ. Believe me, jakes work fine on two-strokes. Example:
WB I-80 from Reno NV to Sacratomato CA has over 70 miles of 4, 5 and 6% grades once you crest Donner Summit. Flip the jake on at the summit, and the coach would settle in between 60 - 62 mph all the way down the mountain, never once having to touch the regular service brakes. Unless, of course, traffic conditions required you to. But your brakes were cool in these situations - not hot from having to control your downhill speed.
Same thing coming off the Grapevine either NB or SB on I-5 - a jake-controlled 60 - 62 mph all the way down the hill, never touching the service brakes.
Next time somebody claims a jake doesn't work with a two-stroke, ask them how much time they've had behind the wheel of a bus equipped with one.
Nick -
Spend the $$ to have a jake installed. It's well worth it, in terms of safety.
Just make sure you've got a good two-stroke technician doing the installation, as some of the set-up is tricky (fast idle buffer switch, for example).
FWIW & HTH. . .
;)
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You need an extra 4 inch clearance (realistically) to clear the higher valve covers. Other than that, the Jake Brakes for the 8V-71 and 8V-92 are the same, so locating a set should not be a problem. What needs to be installed- Installing the Jakes over the rocker arms; wiring the two heads with individual wiring so you have the option of running just one head or both heads. As to the gas pedal micro switch, there are two options for this. One is just running a simple micro switch on the gas pedal that is normally closed, so when the gas pedal is released and pushes the micro switch it turns on the electricity for the Jakes. The disadvantage of this is the possibility of the Jakes still activated at idle and stalling the engine. The other better way is to install the idle switch on the buffer on the governor on the engine (I assume you have a mechanical engine?). This usually replaces the fast idle solenoid. There are kits that you can incorporate both, you'll have to ask your Detroit dealer. The advantage to this is the Jakes will only be activated at 'no fuel' on the governor-which will be during coasting and also if you over speed the engine, but not at idle.
The easy way to wire, is you'll need three wires from the engine to the drivers seat. If you don't have that, just get a 50ft extension cord and use it. I recently bought 5 three wire 50ft cords of different colors and ran them the length of the bus (a bit of a pain, but their in now). What I did was to cut off the socket side leaving a foot of cord. Ran the wire with the cut end to the drivers compartment. Then in the engine compartment mounted the plug side of the cords to the bus and then plugged in the other ends to the engine. This will facilitate not having to cut anything if you have to remove the engine-just unplug it and since their different colors-easy re hooking up. I just tape the joints to keep dirt and water out.
With those three wires, first you'll need an ignition switched power source in the engine compartment. Then run an inline fuse (I think 20amp) and run that power source through the governor switch to the dash. Then you can either run two switches-one on/off, one high/low, or a single pole double throw off-on-on switch.
When I first had the Jakes installed, they were conservatively adjusted so when coming down the Grapevine (5 miles of 6%) I would have to tickle the brakes about 5 times, but no overheating issues. Now that Don Fairchild has precision adjusted them tight, going down the grade is now a no brake decent, in fact I have to switch it in between one and two heads, or I'll slow down too much! Install them, and enjoy a no white knuckle mountain driving!! Good Luck, TomC
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Nick, with your demonstrated capabilities, I do not think you would have any problem installing a set of Jakes. Even the buffer switch adjustment is a piece of cake in my opinion.
And please, do not listen to anybody who indicates that jakes do not work great on an 8V92. My coach weighed over 40,000 pounds and I towed a Tahoe up and down every pass on the west coast as well as all the passes on the east and i guarantee the Jakes eliminated the use of the service brakes in 99% of the cases and also allowed you to comfortably maintain a higher speed.
The above is based on the fact that I lost my Jake Brake operation during one trip to New England and believe me it made a believer out of me. I can assure you it did not take long for me to repair the problem once I got back home.
Again do not pay any attention to the nay sayers. If the Jakes did not help them, then they were not installed and adjusted properly.
Richard
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Tom C posted while I was typing, but I do agree with him 100%. I recommend the buffer switch in the rear on the governor and I also recommend installing two of the small cube type relays in the rear to control the actual Jake solenoid operation. That way the current going thru the cable from the front to the rear and also thru the buffer switch is actually only a few milliamperes instead of several amps. It worked for me!
Richard
BTW, the Jakes would not stall my engine at idle. Not enough oil pressure to operate the Jakes. Might be different on engines where more oil pressure is available at idle.
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I went and looked up the old thread. I thought maybe TomC had posted the comment about jakes not working well on a 2 stroke Detroit, but it was someone else.
I have Jake brakes on my Series 60, but of course it is four stroke. I would personally never buy another bus without Jake brakes or an electric retarder.
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If I was adding one, I'd seriously look into a Telma retarder. Gary (boogie the cat) talks so highly of them. Might be worth a look.
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All Great reply's Guy's!
And I'm learning some more about them now...Thanks!
Richard, Thanks for the vote of confidence but, maybe not a challange I'm ready for yet!!
Jim, telma retarder is also intresting, Does anyone know of a installation simmular to mine?
Tom, your giving me some very good info. Thanks!
At this point, Jakes are sounding affordable since my engine and drive train are fairly new.
Next question....Who can undertake this job for me? I'm ready!
Nick-
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Nick et al, one more piece of advice from someone who has been there and done that.
Make sure the engine is up to operating temperature when you adjust the valve lash and the buffer switch. A few thousands of swell in the steel when the engine heats up can make a significant difference in the operation of the Jakes.
I actually decreased the recommended valve clearance by about .003-4 thousands of an inch. From .059 to a loose .055. That really made a significant improvement and my old time DD mechanic said there was still plenty of clearance for the valves. Ran many thousands of miles like that and no apparant harm to the engine. Again, do it hot.
Richard
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Hi Nick
I had jakes installed on my 6V-92, they work great as I live in British Columbia lots of grades. I got a used set from a wrecker for $800 and paid $800 to have them installed.
Gary
Gary and others,
Where do I start looking for a set of Jakes?
e-bay.. maybay, lol...
Nick-
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Brian -
Whoever made that statement doesn't have a lot of "seat time" in a bus equipped with a two-stroke and a jake.
IIRC, his comments were about an 18-wheeler loaded to 80,000 lbs, a whole different scenario compared to a 30K bus.
Back in my charter driver days, I used to put 80K/year on buses with jakes, working CA, OR, NV, & AZ. Believe me, jakes work fine on two-strokes. Example:
WB I-80 from Reno NV to Sacratomato CA has over 70 miles of 4, 5 and 6% grades once you crest Donner Summit. Flip the jake on at the summit, and the coach would settle in between 60 - 62 mph all the way down the mountain, never once having to touch the regular service brakes. Unless, of course, traffic conditions required you to. But your brakes were cool in these situations - not hot from having to control your downhill speed.
Same thing coming off the Grapevine either NB or SB on I-5 - a jake-controlled 60 - 62 mph all the way down the hill, never touching the service brakes.
Next time somebody claims a jake doesn't work with a two-stroke, ask them how much time they've had behind the wheel of a bus equipped with one.
Nick -
Spend the $$ to have a jake installed. It's well worth it, in terms of safety.
Just make sure you've got a good two-stroke technician doing the installation, as some of the set-up is tricky (fast idle buffer switch, for example).
FWIW & HTH. . .
;)
Hi Russ,
You and Tom talk about that "grapevine" on I-5.
This RT 322 had a decent that sorta pictures in my mind of what you discribe.
At the top, I was able to see the many circles that were to come. at that point the decent
didn't look that bad until thoose sharp turns at the bottom of the steepest drops scare the s**t
out of you! That brake smell is ok for a bit....but after a couple times it quickly changes to a awful stintch..
and then you can notice serious brake fade.
Nick-
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Nick, there are grades in Tennessee and in New England that are as bad as the grapevine on I-5 in California in my opinion. I have traversed all of them several times as well as the other ones in Northern California and the Rockies. I do not remember ever smelling brakes on any of those grades while using the Jake. I know if I started smelling brakes I would be stopped at the next pull off till they cooled down and then proceed down the rest of the grade in a lower gear.
Unfortunately sometimes there is no lower gear to use. I could not get my Eagle with auto to stay in first gear, even with Jakes, when coming out of some of the California back roads and it was really a problem. It would shift out of first at about 15 mph and that was just too fast for some of the passes.
Richard
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While you didn't mention any tranny problems .... you may be interested in this old thread ...
http://www.busconversions.com/bbs/index.php?topic=883.msg12267#msg12267
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Brian, what a great idea and I had forgotten your writeup.
I would like to incorporate that in the Help section of this board so it does not get lost again. Any suggestions how to do it and then be able to find it?
Thanks, Richard
author=Brian Diehl link=topic=4242.msg38628#msg38628 date=1179768535]
While you didn't mention any tranny problems .... you may be interested in this old thread ...
http://www.busconversions.com/bbs/index.php?topic=883.msg12267#msg12267
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Nick,
From what I've seen of Telma retarders (on fire engines), our driveshafts are not long enough and not enough HEAVY framing adjacent to the driveshaft to take the torque produced by the Telma. Jack
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While you didn't mention any tranny problems .... you may be interested in this old thread ...
http://www.busconversions.com/bbs/index.php?topic=883.msg12267#msg12267
Hi Brian,
It seemed that when I downshifted, it sounded like I would be over reving the engine.
Maybe I was just unfamiluar with how to do that.
I'm going to keep reading that thread
Nick-
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Nick, I do not think it will downshift until a safe RPM is reached. I know that even if I pulled mine down to a lower gear it would not downshift until a certain speed was reached and that never had the engine over 21-2200 rpm.
Richard
While you didn't mention any tranny problems .... you may be interested in this old thread ...
http://www.busconversions.com/bbs/index.php?topic=883.msg12267#msg12267
Hi Brian,
It seemed that when I downshifted, it sounded like I would be over reving the engine.
Maybe I was just unfamiluar with how to do that.
I'm going to keep reading that thread
Nick-
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Nick if you buy jakes from someone make sure they have 71-92A stamped on the housing on the top because that the ones that works on a 8v92 engine
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Nick ... Luke might be the closest one to install ... like many have said you need someone how know 2 strokes to set them up or they don't waork worth a dam
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Nick, check out this link - http://jakebrake.com/support/parts-and-service-literature.php?engine_mfr=3&engine_model=28&jacobs_product=25
Should have some answers to your questions.
Hope it helps.
Sammy 8)
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Nick
I found a set at a local truck wrecker, I got the high covers and all related parts for $800. That was three years ago. Try HB Industries they advertise them on their web site. Here is the link.
http://www.hbindustries.ws/
Gary
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Brian, what a great idea and I had forgotten your writeup.
I would like to incorporate that in the Help section of this board so it does not get lost again. Any suggestions how to do it and then be able to find it?
Thanks, Richard
How about copying my reply where I post the solution? You could title it something like: "Manual Torque Converter Lockup Modification"
Would that work?
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Hi Brian,
It seemed that when I downshifted, it sounded like I would be over reving the engine.
Maybe I was just unfamiluar with how to do that.
I'm going to keep reading that thread
Nick-
One solutiont to the "How fast is my engine turning" question is something others have posted before.
Manually put your transmision in 1st. Run the bus up to the govenor and make note of the speed.
Shift to 2nd and do the same.
Proceed through each gear noting the MPH when the motor stops speeding up.
Once you have all the split points you will know at what maximum speed you can shift down into each gear. This should give you the confidence you need to know if you are over speeding the engine or not.
Of course, do this all in a safe and courteous manner (not that you wouldn't). ;)
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Nick
I found a set at a local truck wrecker, I got the high covers and all related parts for $800. That was three years ago. Try HB Industries they advertise them on their web site. Here is the link.
http://www.hbindustries.ws/
Gary
Thanks for the link Gary!
Nick-
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As has been said most recently - TomC is a concientous and totally awesome poster of the facts - I would follow his instructions TO THE LETTER - As to the 2 stroke 8v92, Nick I probably outweigh you by 10k (GVW - 46k+) - Jakes on the 2 stroke 8v92 work fine - 2 speed Jakes on the 2 stroke 8v92 work twice as fine - maintaining your speed on a downgrade is as simple as flipping a switch - HTH - or more perfectly, Hope TomC's info helps -
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Belfert:
I have Jakes on DD8V71 ... wouldn't want it any other way.
Coming down hills from State College, or I-40 from NC to TN ... love my Jakes.
Jerry H.
I recall reading some posts about Jake brakes very recently and I thought someone (TomC maybe) saying that Jakes are not very effective on two stroke diesels.