First trip through mountains

luvrbus · June 30, 2018, 06:57:52 AM

One should learn to descend without the Jakes they can go away in a hurry on a older 2 stroke engine.i am not a huge fan of Jakes on the old Detroit the more you use the Jake on a 2 stroke the more oil it uses.I have always had Jakes I just never used them that much and we traveled all over the west

bobofthenorth · June 30, 2018, 10:14:29 AM

Go as slow as you need to in order to feel comfortable and safe. What's behind you doesn't matter. I see way too many trucks on semi-controlled downhill runaways, one tight corner or stopped vehicle away from a disaster.

TomC · June 30, 2018, 03:54:49 PM

The first thing I had done to my 8V-71 was installing Jakes. I know how well they work from my experience with my 8V-92TA. When pulling my car I weigh 34,750lbs. Going down the north bound I-5 Grapevine-5% grade of 5 miles, I can maintain 50mph without touching brakes. When up in the mountains, I just pull the shifter down to 1st and get torque converter lockup down to 20mph. In 1st the Jakes are really powerful. In my opinion-if you have drum brakes and travel west of I-25, Jakes are needed. Good Luck, TomC

eagle19952 · June 30, 2018, 07:03:52 PM

Quote from: TomC on June 30, 2018, 03:54:49 PM
The first thing I had done to my 8V-71 was installing Jakes. I know how well they work from my experience with my 8V-92TA. When pulling my car I weigh 34,750lbs. Going down the north bound I-5 Grapevine-5% grade of 5 miles, I can maintain 50mph without touching brakes. When up in the mountains, I just pull the shifter down to 1st and get torque converter lockup down to 20mph. In 1st the Jakes are really powerful. In my opinion-if you have drum brakes and travel west of I-25, Jakes are needed. Good Luck, TomC

most don't have 1st gear lock down...

Geoff · July 01, 2018, 05:49:13 AM

I drove many miles in California and Oregon and used the stabbing method to keep the speed down in the mountains. Now I have Jakes and really like them, like Tom says with Jakes you don't need to brake to slow down. However, I had to follow the trucker's advice and set the Jake clearance a lot tighter than the books give you in order for them to work good.

lostagain · July 01, 2018, 07:08:29 AM

The Jakes work quite well on my 6V92TA. They feel about the same as the ones on a loaded semi. I did set them tight. Can't remember off the top of my head how tight, I'd have to look it up. I drive with them on most of the time. It is nice to have as an anchor if you take your foot off the pedal.

On the new Prevost and MCI cars now, the engine brakes (they are not Jakes, they are proprietary systems to Volvo and Cummins), don't come on instantly when you take your foot off the pedal, it takes a few seconds before they activate. So I only use them to go down a hill.

As you get to know your bus, you will know which gear to use to go down what grade. Start slow, and go up from there.

JC

lostagain · July 01, 2018, 07:09:32 AM

The Jakes work quite well on my 6V92TA. They feel about the same as the ones on a loaded semi. I did set them tight. Can't remember off the top of my head how tight, I'd have to look it up. I drive with them on most of the time. It is nice to have as an anchor if you take your foot off the pedal.

On the new Prevost and MCI cars now, the engine brakes (they are not Jakes, they are proprietary systems to Volvo and Cummins), don't come on instantly when you take your foot off the pedal, it takes a few seconds before they activate. So I only use them to go down a hill.

As you get to know your bus, you will know which gear to use to go down what grade. Start slow, and go up from there.

JC

lostagain · July 01, 2018, 07:11:43 AM

Sorry, double post. This new forum platform tells me someone else posted while I was typing, so I hit post. But the someone else was me...

JC

luvrbus · July 01, 2018, 07:43:02 AM

0.055 is about as close as you can set Jakes on a 92 or 71 series me I don't chance it I stick with the 0.059 Jake gauge.I replaced 2 heads on 8v92 where the owner decided if 0.055 was good 0.045 was better.Me and my buddy Don don't see eye to eye on that one he sets those at 0.055,one really needs to know what cam the engine has before he starts playing around with adjustments on Jakes or it will bite you in the @$#

Geoff · July 01, 2018, 08:18:26 AM

Mine are set around .035. The only way you can hurt the engine with the Jakes tight is if you overspeed the engine rpms going down a mountain. That would bend the valves by them hitting the pistons. I've had a few customers do that who did not even have Jakes, and one who downshifted with the Jakes on.

luvrbus · July 01, 2018, 08:27:23 AM

Nope beginning in 1985 when DD started the emission game they were changing cam lifts like people change socks .Set your Jake's on 0.035 on a DDEC engine and see what happens the 1st time you turn it on.0.059 was the safe number for all the cams and I am sure they didn't come up with that number for no reason so it is 0.059 for me

Geoff · July 01, 2018, 08:41:21 AM

I'm talking pre-DDEC, and you're right.
But, what a difference between .059 and .035! Jakes are nearly worthless at .059-- you hear a little puff-puff and keep rolling. I go down the Tehachapi mountains on low Jakes (1 bank) and have to turn the Jakes off so I don't roll to a stop. Without Jakes it was frequent stab braking.

Geoff

luvrbus · July 01, 2018, 08:59:25 AM

The setting on the 71 series was 0.065 the 0.059 was a improvement with the 71/92 heads

lostagain · July 01, 2018, 11:29:31 AM

I looked at my records. .059" is what I set mine at, on Don Fairchild's recommendation. Works good for me.

JC

luvrbus · July 01, 2018, 12:03:15 PM

Quote from: lostagain on July 01, 2018, 11:29:31 AM
I looked at my records. .059" is what I set mine at, on Don Fairchild's recommendation. Works good for me.

JC

Don will go to 0.055 on some engines ,but I don't have problems with Jake's set 0.059 working like they should