Jake Brake Opinion Wanted

[Lin]

I was talking the Don Fairchild yesterday.  He said that he has some Jake sets and some high valve covers.  There are possibly even NOS sets.

[luvrbus]

Ok guys unless you have a torque converter lock up valve and switch which I don't recommend Jakes do you no good when the transmission drops out of lockup and free wheels then most Jakes disengage around 900 rpm on a 2 stroke because of low oil pressure Drive alt 89 from Cottonwood AZ to Prescott Valley AZ and tell me about Jakes 

good luck

[HB of CJ]

Excellent additional information luvrbus and thank you.  For Jake Brakes to work properly, lots of times other equally important additions and adjustments MUST be included....such as fiddling with that pesky lock up clutch on Bus Conversions with automatic transmissions.  I have learned from this excellent forum that gadgets are available for Allision automatics that keep the lock up clutch engaged practically down to just above idle speed...even in first gear.  Very cool.

My old Crown Supercoach 10 wheeler did NOT have that cut off switch that turned off the Jake at a low RPM.  When the Jake was turned on and the schoolie was waiting at one of those seemingly endless Bakersfield red traffic lights in neutral with the clutch out, I had to give the throttle a little bit of foot to keep the engine RPM at around 700 RPM.  If I did not do so and did not just turn off the Jake, the engine would INSTANTLY "Jake" and stop.  No big deal...one just had to get used to it.

Made it nice going kinda slow in about 7-8th gear or sosss with the engine turning about 800-1000 RPM.  The school bus just maintained the slow floating road speed going down hill.  The school bus route then ran about 5 miles West of Frazier Park....I have no idea where it goes today.....if at all.  Pine Mountain did not exist back then.  Anyhow, "Jakes" years ago certainly had their place safely hauling school kids.  I could come off the "Ridge" and make my first brake application and the brakes would stone cold "squeek". HB of CJ

[yeeolde48]

Hi Guys,  I am about to re-power our Scenic with an 8V92 DDEC II and HT748 with retarder.   BK mentioned the retarder offered greater breaking force than Jakes, and some of the research I have done supports that for the 2 strokes.   I haven't seen much discussion on the forum on retarders, what are peoples opinions of retarders, vs Jakes.   
Thanks, Dave

[luvrbus]

They work good Dave just install a transmission temp gauge and keep the temp under 300+ degrees you will like it they are reliable

[yeeolde48]

Thanks Clifford, I will definitely have trans and engine temp gauges.
Dave

[HB of CJ]

Somebody once told me or I read some where that a Jake dumps about 30% of the absorbed energy out the exhaust pipe as extra heat and the other 70% goes back into the engine cooling system...great for maintaining a decent engine coolant temperature while "Jakeing" (sp?) down a steep hill.  And ...a very small percentage gets converted directly into a cool sound indeed.  Just me.  The engine cooling system is designed for this with no problem.  In fact it likes it.

Please think it through.  My old 743 inch 4 stroke 220 Cummins was probably absorbing at least 220 hp through the single stage Jake Brake.  It could and did maintain a 33,000 pound 10 wheeler School Bus with sometimes 60 kids going down a 6% grade right at 25 mph without touching the service brakes.  A automatic tranny retarder absorbs --converts equal or sometimes greater heat energy...but it has to dump it all back into a marginal TRANSMISSION OIL COOLER system.

The tranny oil cooling system MAY NOT be designed for it.  Thus all the required or recommended extra tranny oil coolers.  Even then you may not have enough capacity.  A short story.  Several years ago a un mentioned Type One fire engine, (pumper) came down the Ridge Route at 75 MPH with the tranny retarder set in the max retard position.  The august Fire Engineer, (the driver) did not touch the service brakes.  He did know any better.  $30,000+ damage.

Had the grade been steeper or if he had been going faster, the entire fire engine may have gone up in smoke.  Rumour had it the "chip" indicated over 400 degrees F oil temp?  Anyhow, they had to tow it back to the shops.  The Engineer got off scott free because of...well...use your imagination.  My point is he did know better by training and profession.  He didn't care.  He did not even look at the tranny temp gage or hear the audible alarms....if any.  The average Bus Conversion owner?

Maybe, maybe not.  My greater point here is that sometimes bad things happen.  You can melt an auto tranny with the retarder even if you do know better.  Kinda hard to do so with a Jake.  I for one think a Telsa type electronical (new word) drive line retarder with heat grid may be a better way to go...you do not have to open up the diesel engine to install the Jake.  Also the Telsa type retarders are silent..no small thing now a days.  We all must maintain the political correctness.

My read only.  I love this Bus Conversion Forum.  HB of CJ (old coot)

[belfert]

Om my B500 transmission the tranny temp is almost always within a degree or two of the coolant temp.  I have an oil to water cooler.

[luvrbus]

All depends where the sender is located on a B500 mounted on the sump it will read 20 degrees cooler that the converter out temp the converter is where the heat is 

The Allison's with a retarder do fine up 330 degrees then start watching they can stand 350 degrees intermittent without any problems 

[eagle19952]

So what does a 5 speed Allison non DDEc old school transmission with an external retarder cost ?.....will it fit an Eagle 05/8v71n.
Or an internal retarder....will it fit ?
Can you put one in any transmission ? at what cost / and last where would you buy it...as in where is the best deal....Mexico ?
They got lots'a steep grades in Mexico...and crappier roads....and more kamikaze drivers......something's keeping those guys alive...

[akroyaleagle]

I have a Jake.

The retarders I have used on the H3s quickly cause a lot of heat if used beyond 3rd stage.

I was amazed at how high the transmission temp quickly got. The temp must be closely monitored.

Having said all that, we never had a problem with them, even though we had several not very alert drivers.

I believe damage to the trans may occur if routinely operated above 270 degrees. I learned that from Bob Ware.
Some of you may know him.

[luvrbus]

Bob Ware the ultimate Allison guru have you talked to Bob lately Joe I have tried calling but never can reach him since he retired,the 700 series won't heat as fast as a B500R the cooler on the back of the B500R is real small  

[Melbo]

I have an L10 and it is too tall with jakes so I use a retarder in the trans.  I upgraded the trans cooler according to my service shop.  I have in and out temp on the cooler and a pump that will cool it down if I need to. So on the down hills I turn on the retarder and watch the cooler temp. Turn on the pump for extra cooling if necessary.

It was not set up that way at first BUT a couple of trips over Tennessee Pass in CO and the long down hill into Denver it seemed like a good idea.

As previously mentioned it works fine without but is MUCH more relaxing driving with a retarder (I'm guessing the same for jakes)

HTH

Melbo

[Barn Owl]

I agree with luvrbus. I think they are nice to have but you can live without them. I have been up and down grades and over mountain passes that many bus owners will never, ever take their bus on. I have Jakes and I have intentionally not used them at times to see the difference. I found that without them I have to go slower and be more conscientious of my driving. Probably not a bad thing.

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[akroyaleagle]

Clifford,

I have a home number for Bob. It worked last time I used it. Call and I'll give it to you.