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rondefly

how efective should the Jake brake be?

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I have a 2001 Mack Vision 450 HP the jake has a two position sw and while I am loaded (approx 75000 lbs) going down a 6% hill I have to be in 3rd or 4th low range to hold it back, My question is: is it just not working well or should it be more effective. everyone else is passing me by while I am down to about 15 or 20 MPH.

Thanks

Ron Triano

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It ain't no Jake. Doesn't do much does it. I have one of those "Power Leash" engine brakes, first off, there ain't no power, not enough for a leash. Never even thought of my brakes as far as wear on the C15, the engine break would stop 120,000 on 6% in any gear. Plan on break jobs a little more often.

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I had similar problem, took a while to pinpoint the problem

I started with running the overhead, O rings, wireing and such, it is affected by oil pressure

The next thing is boost

Should be making 15 to 20lbs of boost at 1600 rpm's on 6% grade

Engine fan is around 25 brake horse power

After going through all that, my engine brake was still terrible.

VGT actuator went out, got that replaced and new exhaust manifold gasket

Boost during engine braking went from 5psi to 18psi

Made huge difference, was going off 6% like you, now I go off the same hills grossing 75,000 in 6th or 8th fanning the brake occasionally in 8th near 40 mph

Hope this helped

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I think you have a Dynatard, which is what the "power Leash" replaced because it was so much better lol.

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Don't know if you read owners manual

Engine brake automatically turns off around 1,800 rpm's

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I had a 2001 that had a jakobs engine brake

My power leash does it's best between 1600 and 1800

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I like the Jake better

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Me 2 cents worth sez

FWIW

Wot ever gear n speed U go up ahill with the same load

U should cum down the same hill n load in same gear n may just fan the brakes a bit

so ifn U slog it out up the hill if 3rd @ 20mph

'U should also B in 3rd cumin down the hill (watch them revs) n dont let the wheels over speed U

Jakes work best in the lowest gear @ max revs

cya

§wishy

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Thanks for all the replys, glad to see others have the same problem. hope all you have a nice day.

Ron

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Me 2 cents worth sez

FWIW

Wot ever gear n speed U go up ahill with the same load

U should cum down the same hill n load in same gear n may just fan the brakes a bit

so ifn U slog it out up the hill if 3rd @ 20mph

'U should also B in 3rd cumin down the hill (watch them revs) n dont let the wheels over speed U

Jakes work best in the lowest gear @ max revs

cya

§wishy

I think 40 years ago that may have held more truth but now with the high horsepower rigs that will hold 55-65 mph up hill might be a bit fast for going down hill. Have a good one.

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ok hindsite 55-60mph is probably a little bit fast but I am sure you got the point, new trucks have way more power than they used to and probably can go up in a gear too tall to go down in. See ya.

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I think 40 years ago that may have held more truth but now with the high horsepower rigs that will hold 55-65 mph up hill might be a bit fast for going down hill. Have a good one.

I was told go downhill one gear than you went up lower because of today's aerodynamics. You brought up a great point about todays higher hp/torque engines but the problem I see with with the "same gear" method is there's no guarantee that the downhill side has the same degree of incline as the uphill side. I just choose whatever gear will keep me at a suitable speed and rpm that will require the least amount of braking.

The lamest Jake Brake I've seen is the one in the Sterling I currently drive. If it weren't for the sound I'd have a hard time telling whether or not it was on. Limited effectiveness above 1600 rpm and all but worthless below that.

I don't think the Maxicruise engine brakes were much better but the ones in the MP7 Pinnacles work very well.

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Yeppers GD you're right, use common sense and you shouldnt have a problem rather than trying to go strictly by a rule of thumb.

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Yeppers GD you're right, use common sense and you shouldnt have a problem rather than trying to go strictly by a rule of thumb.

I call it the trial and error/smelly brakes/change of underwear method of learning.

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I just choose whatever gear will keep me at a suitable speed and rpm that will require the least amount of braking.

The lamest Jake Brake I've seen is the one in the Sterling I currently drive. If it weren't for the sound I'd have a hard time telling whether or not it was on. Limited effectiveness above 1600 rpm and all but worthless below that.

I don't think the Maxicruise engine brakes were much better but the ones in the MP7 Pinnacles work very well.

this is true. and the engine brake on that paccar engine is about the same way as your Sterling. It's not nearly as stong as the one on the c-15 cat was,but it's geared higher,got 3.36 rears and the Pete had 3.55's. I can go down Sandstone in 7th. gear at a low rate of speed with 45-46,000 on and not even have to touch the brakes, in 8th I have to hold them lightly all the way down, so I always ease on down it in 7th.

Unless it's snow covered, then I park at the top until a salt truck goes by.

Oh, as for the "rule of thumb"- the only one I like is "you can go down the hill too slow many times, but you can only go down it too fast once."

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My Jake on my Superliner will kill the engine if I forget and leave it on and take my foot off the accelerator too long while downshifting.I had a "Stealth" Jake brake on a '97 CH that you might as well drug your foot out the door.

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I have one with jake and one with dnyotard. They work great if you open both doors wide open and leave the windows rolled up.Cant see any difference in the holding power they have.The jake will make more noise.

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It ain't no Jake. Doesn't do much does it. I have one of those "Power Leash" engine brakes, first off, there ain't no power, not enough for a leash. Never even thought of my brakes as far as wear on the C15, the engine break would stop 120,000 on 6% in any gear. Plan on break jobs a little more often.

I feel your pain. but when I come down a 6% grade I am usually in 4th low split sometimes 3rd high. But I am usually over 145k. That is also 1 to 2 gears give or take lower then I climbed up.

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this is true. and the engine brake on that paccar engine is about the same way as your Sterling. It's not nearly as stong as the one on the c-15 cat was,but it's geared higher,got 3.36 rears and the Pete had 3.55's. I can go down Sandstone in 7th. gear at a low rate of speed with 45-46,000 on and not even have to touch the brakes, in 8th I have to hold them lightly all the way down, so I always ease on down it in 7th.

Unless it's snow covered, then I park at the top until a salt truck goes by.

Oh, as for the "rule of thumb"- the only one I like is "you can go down the hill too slow many times, but you can only go down it too fast once."

You're probably familiar with the 13 mile 6% grade on eb I-68 between Frostburg and Cumberland, MD. With 30k or more in the box, I'd like to be able to drop into 9th (direct on my od 10 speed) and let the jake do most of the work since 9th will have me around 49 mph (45 mph limit) at 1600 rpm. Since 8th gear is too slow, I simply have to apply the brakes as I would without a jake.

The Pinnacles are a different story. They are geared faster, 1420 rpm @65 mph vs 1500 rpm @ 65 mph in the Sterling. On the same hill with a similar load however, I can drop to 9th, turn on the engine brake, and count on one hand how many times I have to apply the foot brake to maintain 45-50 mph.

The EM6 in the R model in my avatar had a Dynatard that worked well. Granted, we never grossed over 45k, but it could almost put you into the windshield on a 10% grade if you weren't careful. When I first drove the truck, the brake was cutting out around 1700. I wrote it up and the mechanic adjusted it to where it was still somewhat effective all the way down to 1400. That truck would just about stall if I forgot to turn off the brake and tried to float a gear.

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You're probably familiar with the 13 mile 6% grade on eb I-68 between Frostburg and Cumberland, MD. With 30k or more in the box, I'd like to be able to drop into 9th (direct on my od 10 speed) and let the jake do most of the work since 9th will have me around 49 mph (45 mph limit) at 1600 rpm. Since 8th gear is too slow, I simply have to apply the brakes as I would without a jake.

The Pinnacles are a different story. They are geared faster, 1420 rpm @65 mph vs 1500 rpm @ 65 mph in the Sterling. On the same hill with a similar load however, I can drop to 9th, turn on the engine brake, and count on one hand how many times I have to apply the foot brake to maintain 45-50 mph.

The EM6 in the R model in my avatar had a Dynatard that worked well. Granted, we never grossed over 45k, but it could almost put you into the windshield on a 10% grade if you weren't careful. When I first drove the truck, the brake was cutting out around 1700. I wrote it up and the mechanic adjusted it to where it was still somewhat effective all the way down to 1400. That truck would just about stall if I forgot to turn off the brake and tried to float a gear.

My Vision is 1650@65mph 4:30 rear gears, I just had the valves adjusted which effects the engine brake, well at least thats when you adjust the engine brake side. I really don't feel it much, but if you shut it off, you realize it is doing something. Had the window down the other day and noticed it when I shifted, could hear it, blurp a little.

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A Mack dealer in Florida once told me that if I wanted my '99 e-tech 460 jakes to work right, I needed to have an oil passages drilled in the head and to also install the high pressure oil pump regulator. I haven't had time to do these mods yet.

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