greg

Jake Brake

24 posts in this topic

I have a 300 e-6 mack engine year 1986 and the engine brake is real weak. Was wondering how to make stronger. It also has a low rpm cutout but its not to low 1400 rpm and the jake stops, how do i get rid of this or lower the cutoff rpm to around 900 rpm's.

Share this post


Link to post
Share on other sites

I have no mechinacal info on how the 6cyl jake can be improved but I have driven a few macks with the Jake brake and they all performed poor in my opinion. At best they would slow the rpms but never could hold back a meduim loaded truck. I think the reson is because of the smaller 673,676, 675 etc... displacement engines??. we have an E9 at the yard with a jake and it stops much better than the small 6 cyl.

Trent

Share this post


Link to post
Share on other sites

its probably a dynatard engine brake is why it doesnt perform like you would expect, that was macks engine brake, it doesnt have the retarding horsepower of a jake, more for the noise than the actually slowing factor, you need to try and find an actual Jacobs engine brake, they are kinda hard to come by we have a 65 bmodel that my grandpa put a 237 in back in the day when they used it as a wrecker, and it has an actual jacobs that works awesome. Good Luck, Jon

Share this post


Link to post
Share on other sites

You can still get a jacobs style brake. 'Bout 1500 bucks!!

Barry looked into it a few years ago for me for my 673.

Share this post


Link to post
Share on other sites

Around here in NJ almost every town have signs restricting Jake or engine brake use, has that been happening in the rest of the country? I figure it's from all the juveniles with their straight stacks blasting the Jake 3 in the morning empty or loaded, it doesn't matter to them. I'll bet they were the ones with all the baseball cards flappin' their bicycle tire spokes when they were kids. Funny thing though is that my DM has it's factory exhaust system and I've never heard a complaint about Dynatard noise in the restricted zones or anywhere 'cause you can't hardly hear it.

Share this post


Link to post
Share on other sites

the signs are posted all the way out to the west coast . most signs say "excessive engine brake use is not allowed" or something along those words.

Share this post


Link to post
Share on other sites

I have a 300 e-6 mack engine year 1986 and the engine brake is real weak. Was wondering how to make stronger. It also has a low rpm cutout but its not to low 1400 rpm and the jake stops, how do i get rid of this or lower the cutoff rpm to around 900 rpm's.

Are you sure it's a jake? Maybe it's a dynatard which is like pissing in the wind. I'm not sure on the cut out my dog stalls if I'm dumb enough to forget the dynatard is on( and it's happened more than once!)

Share this post


Link to post
Share on other sites

You can still get a jacobs style brake. 'Bout 1500 bucks!!

Barry looked into it a few years ago for me for my 673.

Damn straight. I just got the jacobs style 2 stage put on my truck last month and that's what it cost me! It works great. They aren't hard to come by.

Share this post


Link to post
Share on other sites

its probably a dynatard engine brake is why it doesnt perform like you would expect, that was macks engine brake, it doesnt have the retarding horsepower of a jake, more for the noise than the actually slowing factor, you need to try and find an actual Jacobs engine brake, they are kinda hard to come by we have a 65 bmodel that my grandpa put a 237 in back in the day when they used it as a wrecker, and it has an actual jacobs that works awesome. Good Luck, Jon

Does it have a wire on top of the valve cover, if it does it is a dynatard , a jake has a spacer plate under the valve cover and the wire comes out of it.

Share this post


Link to post
Share on other sites

Just got a rebuild kit for my 2 valve 237 Jake brake.

The cost was $95.00 plus shipping. Got it from Tec Brake.

If the 'O' rings are hard, cracked, etc. or pistons galled, the brake won't work to it's capacity. On Cummins that's about equal to the rated horsepower. Macks do not have the injector rocker arm to get top-dead-center on the exaust stroke quite as well as the Cummins engines but is still way ahead of a dynatard.

Packer

Share this post


Link to post
Share on other sites

if you have everything adjusted properly,a Dynatard works damn good.I have no complaints about the one I have in my Superliner.

Share this post


Link to post
Share on other sites

We have a factory installed Jacobs-brand Jake Brake on our '90 CH613 with a E6-350, and it's absolutely useless. It barely even slows the truck down while bobtailing. The local dealer said that's probably about all it was good for when it was new.

Dan Bruno

www.stlouisdumptrucks.com

Share this post


Link to post
Share on other sites

On a Cummins engine, with only one head turned on, and a new rebuild on the engine brake, the brake will kill an engine at idle. With all working and even a little oil leaking by, the brake will kill an engine at idle. With the engine idling and you here a little putt-putt-putt sound, that's an indication the brake is in need off an hour or two of TLC.

The only dynatards I ever drove were while test driving at the Mack shop in S.L.C. UT. At that time, the only other engine brakes were Cummins and that was just after I had rebuilt them.

The Dynatard may have been weak and I know the Jakes were strong so I may not have had the whole story.

When driving with and for my Dad, we would get 350,000 miles from a set of brake linings. when drivers were add, the brake life dropped to 150,000 miles.

When lease O/O were added, trailer lining went to 50,000 miles.

The old Jake instructions said to "Use the same gear going down hill as going up"!

Something to think about!

Packer

Share this post


Link to post
Share on other sites

We have a factory installed Jacobs-brand Jake Brake on our '90 CH613 with a E6-350, and it's absolutely useless. It barely even slows the truck down while bobtailing. The local dealer said that's probably about all it was good for when it was new.

Dan Bruno

www.stlouisdumptrucks.com

On a international 4300 i drove at the international truck tour they had a 3 stage jake brake on the dt466. it was STRONG! On the 3rd setting and let off the gas it nearly threw me thourh the wind sheild! The system has a bleeder brake in combination with an exhaust brake. The cat powerd 7600 had a jake and it was very strong. I guess it depends. Must stop drinking.

Share this post


Link to post
Share on other sites

Does it have a wire on top of the valve cover, if it does it is a dynatard , a jake has a spacer plate under the valve cover and the wire comes out of it.

I know it's a jake because of the spacer plate that says jacobs on it. How do you adjust the brake?

Share this post


Link to post
Share on other sites

you can adjust it like you adjust your valve lash. don't know the spec but it's the same way you have to rotate the engine and everyting... (too long to explain..) but well adjusted jacob works great on Mack engines. Dynatard from Mack are great on 4VH engine. 2VH with dynatard help when bobtailing...

Share this post


Link to post
Share on other sites

The adjustment is something like "Down to touch and back off 5/8 (or 3/4) turn".

Be sure the valve lash is set first, then adjust the Jakes. Incorrect valve lash will mean incorrect Jake adjustment.

Packer

Share this post


Link to post
Share on other sites

On a international 4300 i drove at the international truck tour they had a 3 stage jake brake on the dt466. it was STRONG! On the 3rd setting and let off the gas it nearly threw me thourh the wind sheild! The system has a bleeder brake in combination with an exhaust brake. The cat powerd 7600 had a jake and it was very strong. I guess it depends. Must stop drinking.

I never did see one of them jake brakes on a DT.May be a new deal.But they ant big enough to be too powerful. Glenn Akers

Share this post


Link to post
Share on other sites

Packer is absolutely correct. I run the adjustor down till the jake it hitting slightly and then back it off 3/4's. Mack jakes arent great but they do ok. The dynatard on my 4 valve does a good job.

Share this post


Link to post
Share on other sites

yeah where can you find info on the dt466 jake or engine brake..i have never seen one. that was one of the bad things about a dt 466 because it can't have ajake.. if they make one pleaae let me know i know a few who would like them.

Thanks

Deo

Share this post


Link to post
Share on other sites

yeah where can you find info on the dt466 jake or engine brake..i have never seen one. that was one of the bad things about a dt 466 because it can't have ajake.. if they make one pleaae let me know i know a few who would like them.

Thanks

Deo

Here is the link for information on the International engine brake. It is only available on the new 2004 I6 engines (DT466/570 HT570). Don't know if they can be field installed but I would ask anyway. Its also quiet. When I tried it All you herd was the engine rev up a little.

http://www.jakebrake.com/products/md-bleeder.php

Share this post


Link to post
Share on other sites

"www.tecbrake.com",

800-322-9609.

These people fixed me up!!!

Sharp people and no run-a-round!

Call them or e-mail.

They have rebuild kits, adapters, all the stuff a guy might need.

And prices were good.

Packer

Share this post


Link to post
Share on other sites

Howdy any engine brake is better then none a proper Jake really helps you may have to downshift though-this area has a lot of steep grades and my brake life exceeced 200k on a rd690 back dump with a 2stage Jake mostly shorthaul stop and go-we werent always legal either.Some of the the rest of the guys had problems getting good brake life-a few high speed stops really shortens brake life you can run sensible & have the same load count.Yes retarder restrictions in town are very annoying-but shoot DOT got pay the the salarys someway-Kevin

Share this post


Link to post
Share on other sites

Howdy any engine brake is better then none a proper Jake really helps you may have to downshift though-this area has a lot of steep grades and my brake life exceeced 200k on a rd690 back dump with a 2stage Jake mostly shorthaul stop and go-we werent always legal either.Some of the the rest of the guys had problems getting good brake life-a few high speed stops really shortens brake life you can run sensible & have the same load count.Yes retarder restrictions in town are very annoying-but shoot DOT got pay the the salarys someway-Kevin

Thanks guys , it turns out I do have a dynatard, now that it is adjusted it work pretty good. Thanks for all the input , great help. :chili:

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now