| Author |
Message |
Bradd B. Smith (Bbsrtbusproject) (208.26.165.155)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, August 10, 2002 - 12:35 am: | |
I recently had a conversation with my mechanic regarding Jakes on my coach. It has a 6v92ta and an Allison v730 slushbox. He said to save my $money$ because they would not amount to much with the auto. Is this the truth? I live in the west and would really like to have them if they WORK! I would appreciate some feedback from our esteemed readers. Thanks! |
ron rice (12.228.12.48)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, August 10, 2002 - 1:10 am: | |
I drove a number of coaches out here in the west that were powered by 8v71, 6v92, 8v92 and series 60 detroits that had jakes. If you manually select the gear that you will decend a hill the jake will give you good breaking. If you let the transmission select it will just go to the highest gear which will provide no braking.
The old saying was decend a hill in the gear that you would climb it, however, now that we have the big 475 horse engines that is not as true.
Greyhound has run for years and never used Jake Brakes on their coaches. You just have to downshift the transmission manually and keep it under control. |
Richard Bowyer (Drivingmisslazy) (66.190.119.82)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, August 10, 2002 - 7:29 am: | |
Brad, I would suggest you find a new mechanic. I have an 8V92 with Allison 740 with Jakes, and they work GREAT.
My eagle weighs about 40,000 pounds and I tow a 5500-pound Tahoe. With judicious selection of the proper gear (manually) to keep the engine in the 1600-2300 rpm range it will maintain the proper speed in almost all cases. Even on level ground and in city type driving I use them to control my speed. DON'T LEAVE HOME WITHOUT THEM.
The secret to proper use is to try and maintain a higher engine RPM for desired speed.
I have driven extensively throughout the western states many, many trips. Including both ways on the grapevine in California, the passes on I-5 in Oregon, Baker grade between Baker and Los Vegas, Eisenhower pass in Colorado and all the other Colorado passes and most of the long steep grades in Utah, Arizona, Nevada on every east-west and north-south freeway and everything in between. Also throughout the eastern states where there are some grades that it is nice to have. Especially in Tennessee, North Carolina, West Virginia and the northeastern states. In all cases, I seldom if ever use the service brakes. Try this without the Jakes. It is impossible to maintain proper speed with engine braking only in most of these areas.
Prior to descending, or part way down, if necessary, I shift down to the appropriate gear (using the brakes, if necessary, in this case) and then travel down the grades all the way without use of foot brakes.
I have well over 100,000 miles on my coach and am still on the original set of brake shoes and they are still in excellent condition. I suspect I would have had to change them two or three times without the Jakes. I would never try and travel the western states without them. They are an excellent investment.
Richard
P.S. This is from personal experience, not something I have heard, read or taken off the _hit house wall. LOL |
Don KS/TX (63.15.244.30)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, August 10, 2002 - 8:40 am: | |
I have driven V730 with jakes, they work just fine with that transmission. |
mel 4104 (208.181.100.5)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, August 11, 2002 - 10:38 am: | |
bradd, i drive a 4104 with a 6/71 inline with a 2 valve head with a jake, i tow a king cab mazda all around B.C.,ALBT.,WASH.OR,CAL,AZ,NM. TEX. NEV. and have never had a problem so using the auto with a jake ,just bown shift it before you head down the hill and it will work great just keep the RPM down and it will work like a 18 wheeler, sound like one to just do not use it in any town or city or people will know that you got your drivers lic. out of a box of pop corn. mel 4104 |
Richard Bowyer (Drivingmisslazy) (66.190.119.82)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, August 11, 2002 - 1:10 pm: | |
Mel, I believe that the lower the engine rpm, the less effect the Jake has on braking. I suggest running at the top end of the rpm range. BTW, I have a large muffler on my 8V92 and the Jake noise is very low so I can use it at any time without creating noise pollution. However, it sure sounded a lot nicer originally when I had no muffler. Nothing quite beats the sound of an un-mufflered Jake in my opinion. LOL
Richard |
mel 4104 (208.181.100.22)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, August 11, 2002 - 1:45 pm: | |
Richard, you are right on if you have ever driven a logging truck on ahill with a 13* slope and the haul back line breaks1/2 the way down the sound of that jake cutting in is the sweetest musick this side of the harp in the here after,but right then it is the best there is, the smell in the truck cab is not very good beleive me, and you shake like a leaf every time you go back up for another load over the next few days. mel 4104 |
Richard Bowyer (Drivingmisslazy) (66.190.119.82)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, August 11, 2002 - 2:15 pm: | |
Sounds like an experience I would rather pass up.
Richard |
Stephen Fessenden (Sffess) (208.230.117.50)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, August 11, 2002 - 8:04 pm: | |
Usually you will be able to use the Jake alone on downgrades but you may have to use the brakes occasionally on very steep grades to keep the engine RPMs below the shift point. Still the Jake does almost all of the braking and prevents the brakes from overheating. My Allison 754 will automaticly upshift at 2250 RPMs, so I touch the brakes to drop the speed and RPM. If I have to use them very much then I slow way down and select a lower gear. |
Richard Bowyer (Drivingmisslazy) (66.190.119.82)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, August 11, 2002 - 8:56 pm: | |
Mine operates a little different, so maybe there is some adjustment that can be made by an Allison shop to change operation.
In mine, once I pull it down into third or second it will stay there regardless of rpm. At least I have had mine up to 2500 rpm and it never shifted.
First gear is another story. It will not stay in first above a certain rpm, but I really do not remember what it is. This creates a problem on some of the secondary roads I have been on in California as the speed to negotiate the turns and safe speed is 10-15 mph. This is also about the speed that the tranny torque converter lock up drops out. In those cases, I had to come down all the way using service brakes only.
The grades were identified as not recommended for tractor trailors or busses, but the sign was so far down the grade that there was no place to stop and turn around. On grade in particular was coming west from Yosemite park that was particularly bad.
There is another bad one coming into Tennessee from North Carolina into the Smokey mountains on the way to Gatlinburg.
Richard |
john foote (206.191.131.120)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, August 12, 2002 - 1:56 am: | |
The retarder on the Phantom M-11/B400 I drive is adjustable. Don't ask me how, but the shop lords decided they wanted the retarder to brake a little harder. And lo, it came to pass, overnight. The whole fleet started retarding a little harder. Some drivers whined about it (some drivers whine about everything), but I love the higher setting. The more you pull your foot off it, the more the retarder retards, so you can just sort of ease off the throttle, and pick the degree you want. It's not perfectly fluid, but I think there's at least three stages involved with each gear, as in coast, mild and full. The higher the revs, the more kick you've got to play with. I do a lot of driving, in traffic, up and down twisty hills, without touching the brakes at all. Sweet set-up. |
jmaxwell (66.42.92.2)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, August 12, 2002 - 2:23 am: | |
John: Are u talking trans. retarder or jakes? |
Don KS/TX (63.15.244.176)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, August 12, 2002 - 6:12 am: | |
The retarder on a recent MCI Renaissance was driver adjustable. You just put the little lever at what stage you wanted to brake, it would do it all from slight drag to a real "slide the passengers from their seats" setting. You can literally drive it with throttle foot only, adjusting for level ground or super hilly country. Only drawback, when doing heavy retarding, the temp gage goes up in a hurry! |
Buswarrior (Buswarrior) (64.229.209.158)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, August 12, 2002 - 8:23 pm: | |
Hello Brad.
Before we have your mechanic shot (but only just before, to be sure we're getting the whole story) I'd ask him what he means.
He may be hesitating because with a 730, you have very big spreads between the 3 gears, and keeping the jake working strong will only happen at certain road speeds. It will still drag along very nicely, even if the RPM are less than best. So, firing squad, load your rifles.
He may also be hesitating if he thinks he knows how many miles you plan to drive a year, and wants to save you from sinking a ton of money into "brake savers" when you won't wear out the brakes in 25 years of driving, due to small mileage. Depends whether he's afraid you'll run off a cliff somewhere and whether he's worried about you, or your business.... ah, just shoot him, there's more mechanics out there.
Don't rush out and get jakes just because everyone else is doing it. The entire transportation industry managed quite nicely without them for many years. You just go down the mountain slowly enough, and down enough gears that you don't use the brakes too much.
As noted by Ron, Greyhound has chosen not to run jakes until quite recently on their equipment. I'm of the opinion that if the 'hound don't run 'em, then they don't save enough money for what it costs to maintain them. Greydog is in the business to make money. period. They rarely spend one red cent more than necessary to put the coach down the road.
Also, jakes let you go down the hill at speeds which would make an oldtimer flinch. Lots safer to keep your drivers slow within the limitations of their brakes than to let them get used to flying down the hill and then have to compensate for a failed jake.
If you have cash to spare and you are making an informed decision, go ahead and get jakes, but don't feel you have to.
I drive highway and teach transit. I've driven MCI 102DL auto with jakes, auto with retarder, and 7 speed with nothing, Renaissance auto with retarder and jakes, H3-45 auto with jakes, MC9 auto and 5 speed with and without jakes, transit buses auto with retarders and nothing.
Personally, I prefer the driver controllable retarder in the Allison B500R auto transmission, as Don told us about, but that won't be a busnut option for another 20 years!
If you boil it down, having a jake or retarder for most of us just means you don't have to pay as much attention while coming off a mountain, which is a nicer thing as we all get older.
Many of us are going to have the brakes go bad from lack of use, or contamination from wheel seal seepage, before we wear them out. Just because you have lots of brake lining doesn't mean it is gripping!
When was the last time you did a brake test with your bus? When was the last time you had the drums pulled? If it had to pass the commercial inspections, would it be declared fit or unfit?
So, what about me? My MC8 with HT740 doesn't have jakes, and the motor doesn't smoke once it is warmed up. If I happen to stumble on a cheap set of jakes, I'll pick them up and wonder about doing the heads sooner than later.
If my motor needed work, I'd think hard about installing them now, just for the convenience. You don't have to put the switch on, unless you want to, but you can't turn on what isn't there?
so, more grist for the mill....
happy coaching!
buswarrior |
FAST FRED (63.208.84.226)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, August 13, 2002 - 5:32 am: | |
The Jakes Mfg will send you the instalation & service books.
Be sure you really need them before installing equippment with a rather large Annual service requirement.
FAST FRED |
Richard Bowyer (Drivingmisslazy) (66.190.119.82)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, August 13, 2002 - 11:07 am: | |
FF, What is the annual service requirement? Once the proper clearance is set (.059 or.064 depending on the head) I can think of no other requirement. I have had mine for 15 years with no special service required. Even if you wanted to check the clearance, it is only a simple matter of removing the valve covers and checking it.
Richard |
Don KS/TX (63.15.249.245)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, August 13, 2002 - 1:46 pm: | |
And for those looking, it is the "Jacobs Manufacturing Company" Jakes is just an old dumb truckers term. I have had them for many years, never done a lick of maintenance yet, and just looked at my book from them, it mentions no maint required either. |
Joe Laird (Joelaird) (205.188.197.37)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, August 14, 2002 - 10:51 pm: | |
My jakes may be the best investment I've made on the bus. I bought them new instead of rebuilt but think rebuilt would have been ok.
The manual says .065, mine were set to .055 on the 8V71 and adjusted by "experience" on the 8V92. They have always worked GREAT!
I have a 740.
I also run a muffler and leave the jakes on all the time. Mine has 2 stages. I only use both stages and never half the jakes.
I tow a large trailer all the time and like the braking action. I can exit the freeway at 70mph and will have to push the accelerator to keep from getting to slow before the stop sign.
My transmission goes out of lock-up about 18mph so the jake stops there but that is long before the stop sign usually.
For the jake to work best, the engine needs to be above 1800rpm, preferably nearer the max no load speed when descending big grades.
We've got H345s and Renaissances, Some with jakes and some with 6 stage retarders. The jakes are 1/2 or full. All of them work fine but the retarders REALLY make the trans temp gauge go up if they are used above the 3rd stage.
We trade them all in at the 5 year mark and so far have not had transmission troubles due to the retarder.
Hope this helps, Joe Laird |
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