I read on Barry's site the 50 reasons to love your Foretravel and came across this statement
I know it says every coach, but when was that statement written and does it include all the 4 speeds?
Not on the older units and there was one or two that the new owners tried to push thru without it as well to save money. They did not sell. The older GVs have jakes. You will see the retarder onthe allison transmission 3066 and 4066 I think.
Some 89 GV's with the DDA with the 4 speed Allison did have the retarder. Must have been very unusual.
Dave M
Am I recalling correctly that it was the 2007 Nimbus (and possibly '08) where the retarder was not standard but available as an option? Not sure on the '06 Nimbus (very few built) which was the '02-05 style U-series with a different name.
Michelle
To my knowledge the U225's did not have a retarder or Jake. They came with the Cummins 5.9 ltr engine. Most people had an exhaust brake, like the PAC brake installed but a supplemental braking system did not come as standard equipment.
I have a 1993, U300 with the 350hp Detroit. I came with the Jake and I like it very much. It does the job on the steep grades and does not create heat but it is not as versatile as the transmission retarder.
Generally speaking, I think you'll only find a four speed with a retarder on a U300 between the years 1987 and 1991. In 1992, the Jakes became standard on the U300s.
The controls on these earlier retarders only worked with the brake pedal (i.e. no joystick) where about 1/4 brake force would give you full retarder.
That said, when it comes to shopping for a coach you need to investigate each unit to be sure. These coaches were often customized and I know I'm always running into a feature or configuration that I didn't think existed. Like yesterday where some brought up the existence of a 1993 U280 with basement air conditioning - I would have never guessed.
I have an 89 Grand Villa, what is a DDA.
Detroit Diesel Allison
I saw one on RVtrader that had the air in the bay. I might have to have a look at it as it is in my price range.
And some of the older GVs such as the U225 have exhaust brakes, which is a completely different animal than the Jacobs engine brake (Jake brake).
You drop a Banks kit on that C8.3 and you'll think you've got 450.
Actually, you could only fit an exhaust brake (no engine compression brake) on: Cummins B and C and Caterpillar 3116 and 3126.
michael j,
I have the 2 stage jake brake with a 93' U300(built in nov 92') and a 4 speed allison. I've only had it since last march and in my limited driving experience so far even with the 4 wheel disc brakes, the Jake makes a huge difference and I really like it. The roar of it really lets everybody around you know when you're slowing down!
Jerry
Hummm I can barely hear mine. Makes me wonder if mine is working properly. Any of you 6v92 owners want to weigh in?
see ya
ken
Ken,
Have you tried listening to it with your driver's side window open. Not only should you feel it, but you should be able to hear it loud and clear. My shop is located on Hwy 49 and I get to hear trucks with jakes all day slowing down to cross the railroad tracks about one block away and 4 blocks from the entrance to the port of Gulfport on Hwy 90. Sometimes they're loud enough to rattle the windows. Between the trucks, trains and sirens it can get really noisy around here!
I went through the small town of Louisiville, Ms a couple of weeks ago on my way to Legion state park and there was a "No Jakes" sign at the city limits. I'm sure they don't want you waking people up late at night going through there! I'll bet Pierce has some funny stories about Jakes as well as some of the old truckers on this forum.
I can't wait to hear it when I go through the Mobile tunnel!
Jerry
Actually, the U300 is the first Jake equipped diesel I've driven. All of our fire apparatus and my 4107 were non-Jakes. One International (with 1000 gallons water, 200 gal fuel) had a trans retarder with a big yellow heat warning light on the dash and a pedal on the floor to go with it.
Yes, the big 14 liter 4 cycle rigs make a lot of noise with the Jake on. Think most the noise comes from minimal mufflers. I keep the Jake switched on around here in the Sierras. It's not very noisy so I don't even pay attention in residential neighborhoods. The 6V-92TA has a pretty efficient muffler and at 5 inches, it flows a lot of air but doesn't bring the noise with it. I do like going through tunnels a full throttle with the window open. Great sound. For people used to Cummins or Cats, the Detroit fires each cylinder each time the piston comes up in contrast to the 4 cycles firing every other time. So a 2 cycle Detroit at 2150 sounds like any other engine at 4300 rpm. Our fire apparatus shut the fuel off at 2400 rpm so the blower and exhaust sounded like a race car at almost 5000 rpm.
I can remember sitting for hours on my top floor balcony of a high desert Mexican hotel on a hot night . All the Mexican buses had 8V-71s without mufflers, just a 90 degree turn in the exhaust pipe and out the back. You could hear the same bus for several minutes as he went through gear after gear and then matched rpm with the throttle, downshifting while passing other cars and trucks. The eerie howl cut through all the other city noise and was impossible not to marvel at in the darkness. A desert creature battling any and all in it's way. From that night on, I knew I had to have one of my own one day.
You can't believe what they sound like trying to blow out a palm tree fire with the deck pipe from your fire truck. The throttle on the pump panel is screwed all the way out, the tach is at 2400 rpm and even with headphones on, the noise from all the gears, supercharger, exhaust and fire pump go through the headphones like they weren't on your head. All this while pushing up to 1000 gallons of water a minute out the nozzle.
As Cagney would say, "Made it, Ma! Top of the world!"
Pierce
Agree with Pierce, when I had the 12V-71 in the MCI, at 2100 rpm going thru tunnels, speed about 60 mph, hitting the Jake Brake, traffic would stop behind me, guessing their thought was the end of the world was happening, oh yes, not good mufflers, looked like mufflers but home made to fit the space, not too effective.
Enjoyed the Boys & Toys approach.
Dave M
As said previously, I can barely hear the Jake with the windows shut but can defineitely hear it with the drivers window open. I can also feel the difference between Jake 1 and Jake 2 position. It is a subtle reduction in speed and if used on long, steep grades you must use the service breaks to slow down to the speed you want, then the Jake will hold that speed if you are in the right gear.
I have seldom seen the transmission temperature gauge move except in really hot summer temps driving in stop and go traffic. But since it has moved I am assured that it is working and unlike a transmissio retarder it has little effect on the engine temps.
Ken, can you feel the difference when the Jake is on?
@Kent I do feel and hear (with the window open) the jake on downhills. I don't feel much difference at all between Jake 1 and Jake 2. I generally don't use the jake unless I'm in the mountains or the rare long downhill. I'll use it coming to a stop on an exit ramp sometimes just to exercise it.
To me the jake is no where near as dramatic as downshifting a gear. Feels more like downshifting 1/3 of a gear. I've had no problems downshifting and using the jake in the mountains of Colorado. Just use the service brakes to slow when needed. No problems overheating the brakes or overreving the engine.
Stewart & Stevenson checked out the system and replaced the jake control module (under the dash) for me about a year ago. I heard nothing from the jake before that so I do believe it's working. Maybe my expectations where/are too high.
I was a complete naive when I purchased the coach. Didn't even know it was a 2 cycle! :) Was a little skeptical about it when I found out. The more I learn about my 6v92 the more I like it and as I was told by one diesel mechanic "my heart throbbed a little bit when I heard you pull in". I feel that every time I start it now. <3 Wayne at FOT confessed to me that it was his favorite engine. He may tell that to the cummins/caterpillar guys too. :)
see ya
ken
Keep in mind the Jake is more effective at higher rpm, so down shift, get rpm up, it will be so much better.
Dave M
Echo Dave on the RPM. To even get to highway 49, it's 10 minutes of up and down steep hills. In fact, there are so many grades here that I keep the water tank and fuel tank near empty. On I-80 over Donner Pass, with the Jake on, I use the service brakes twice on the way down to Truckee. The interstate grades are usually pretty mild so a decent in 4th (high) gear w/Jake is a sleeper. On steep, 2 lane roads like the 10% approach to Jackson, Wy, I stop the coach, select 1st, accelerate, shift to second, accelerate until it shifts to 2nd direct and then back off and let the Jake do it's work. With toad, we were able to come down the steep grade without holding up traffic with a moderate use of the service brakes. We could have made a service brake free decent if we came down in 1st.
Jake brakes use the back side of the compression stroke to allow the engine to slow the vehicle. Retarders use the transmission for braking. Both have advantages and disadvantages.
In starting any decent, a quick glance at the air pressure, speed and selecting the proper gear make for a non-event especially if you think you may be over gross weight. Whatever your political leaning, this is a time to be very conservative ;D and plan way ahead.
For a more in depth explanation of the Jacobs brake and links to Pac brakes, Banks Power Brakes, see: Compression release engine brake - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/Compression_release_engine_brake)
Pierce
Pierce,
Thanks for the info on Jake brakes, etc. and your advice on mountain driving safely without becoming a aggravation to others. Your description of the palm tree fire and listening to the buses from your hotel balcony on a hot Mexican night was like reading from a novel!
Dave M,
I agree with your advice on rpms. You can really feel it when slowing down, the rpms are around 2000 and the gears are downshifting especially from 2nd to 1st. At 30,000 lbs going downhill that's a big confidence booster!
Thanks-Jerry
Years ago I was writing specs for a new E1 Aerial Tower for the Fire Dept. This was the first new piece of apparatus I had specified for them. Our fleet standard heavy engines were CATs so I put that in. Chief asked me out to lunch day after he got the spec's for comment. He said he really wanted a Detroit. After many B.S. reasons he finally fessed up and said that CATs were OK but the Detroit just sounded so much better. He got his Detroit. Pierce is right a Detroit in full song pumping for all it's worth is quite something to hear.
Keith
88 GV 3208 CAT Turbo 300HP
How would you know if the 4 speed Allison has the break and if it is working?
Fouroureye,
If you have a transmission retarder you will have a switch on the dash labeled "retarder". In that vintage (same as mine) the retarder only works when the switch is "on" and the brake pedal is supplying some air pressure to the brakes. The retarder is very noticeable. It's most noticeable with very light braking and there is about a 2-3 second delay after applying the brake pedal. The retarder switch will also illuminate when the retarder is active. I beleive retarders were standard on only the U300 which came with the Detroit 6V92.
The 88 would not have had a retarder, but someone may have added a pac brake, but if they did there should be a switch and also by lifting the bed, check the exhaust coming out of the collector after the turbo to see if the brake mechanism is located there
I currently own a 2006 Nimbus and according to the original owner,(Cindy Young), the retarder was an option when her coach was built. She and her brother stopped by today (Sun,13th) to say hello while I'm here at FT. It was a very pleasant surprise. She has not only provided me with a lot of information about the coach but pictures of the build process. Thank You Cindy. They are here in Nac having some graphics added to her coach at Xtream. She said to tell everyone hello.
When the new owners took over they made the joystick retarder and the retarder in general an option and built one coach without it. The uproar was pretty intense and the coach sat for a while. They put them back on standard again after that short experiment.
Here is the 2006 Retail price sheet on the Nimbus showing the retarder as an option for 4425.00
I remember when I saw this "Retarder as an option" originally I thought the new owners were going to lower the standards of the Foretravel.