Adding a hydraulic or electric retarder to a 5-ton

[Robo McDuff]

With the older 5-tons (m39 and o00 series), there is an ongoing discussion if and how to make the single brake system in a dual circuit, to help avoid catastrophic loss of brake power.

I am looking into it again, and ran across the hydraulic or electric (mag) retarders as additional brake power. It will not help you in an emergency situation, but it might help save your brakes and keep your vehicle better under control in normal daily use.

Question 1) did anybody ever added such auxiliary brake system to the older 5-tons?

Question 2) would it work on the old 6x6s at all?

Question 3) does the more modern 900 series have such systems, either standard or later added?

Question 4) Did any of these trucks ever had a jake-brake and would that work?

Edit: here a link to a guy who actually linked an electro retarder to a permanently engaged PTO. If that would work, that would certainly be a sweet modification without ruining the original aspects of the truck or needing to redo your drive-shafts

 

[73m819]

With the older 5-tons (m39 and o00 series), there is an ongoing discussion if and how to make the single brake system in a dual circuit, to help avoid catastrophic loss of brake power.

I am looking into it again, and ran across the hydraulic or electric (mag) retarders as additional brake power. It will not help you in an emergency situation, but it might help save your brakes and keep your vehicle better under control in normal daily use.

Question 1) did anybody ever added such auxiliary brake system to the older 5-tons?

Question 2) would it work on the old 6x6s at all?

Question 3) does the more modern 900 series have such systems, either standard or later added?

Question 4) Did any of these trucks ever had a jake-brake and would that work?

Edit: here a link to a guy who actually linked an electro retarder to a permanently engaged PTO. If that would work, that would certainly be a sweet modification without ruining the original aspects of the truck or needing to redo your drive-shafts

#4 -- Yes, ALL the Canadian 809s were jaked, the hood was different to accommodate the jake.
#5 -- A EXHAUST BRAKE could be used, it would work.

 

[red]

For the older m39 series trucks there is no jake brake available for the engines they used.

A exhaust brake will work and is relatively cheap.

The electric brake looks like another option but has 2 challenges over a exhaust brake. 1. Cost. 2. Mounting location. With the shorter wheelbase of your truck the driveshaft that goes from the transfercase to the middle axle would have to be shortened, which could lead to limiting the movement of the rear suspension.

 

[gimpyrobb]

Bjorn(Cranetruck) put an exhaust brake on his deuce and reported it worked very well. Thats the route I'll go if I ever find one cheap.

 

[Robo McDuff]

Bjorn(Cranetruck) put an exhaust brake on his deuce and reported it worked very well. Thats the route I'll go if I ever find one cheap.

Thanks for the interesting replies.

Here is the link to that post of Cranetruck.

And another interesting thread. This one mentions Telma retarders, which I was reading about also.

I read about Jake breaks and exhaust brakes. Can't find that article back, but I think it mentioned that an exhaust brake would put a lot of pressure on existing exhaust which might not be strong enough, rpm must be kept high for it to work good and some other problems, cannot remember what it was. The Jake brake looked too complicated to get functioning on an M51A2 multi-fuel. That was my feeling reading it, maybe I was wrong.

Reading some remarks in the second linked thread and elsewhere, can an M51A2 multi-fuel handle an exhaust brake or do you need true diesel engines for it?

I probably can forget finding an exhaust brake on a European scrapyard, older retarders might be easier.

 

[grendel]

I am putting a pac brake on my M932A2.

 

[red]

Thanks for the interesting replies.

Here is the link to that post of Cranetruck.

And another interesting thread. This one mentions Telma retarders, which I was reading about also.

I read about Jake breaks and exhaust brakes. Can't find that article back, but I think it mentioned that an exhaust brake would put a lot of pressure on existing exhaust which might not be strong enough, rpm must be kept high for it to work good and some other problems, cannot remember what it was. The Jake brake looked too complicated to get functioning on an M51A2 multi-fuel. That was my feeling reading it, maybe I was wrong.

Reading some remarks in the second linked thread and elsewhere, can an M51A2 multi-fuel handle an exhaust brake or do you need true diesel engines for it?

I probably can forget finding an exhaust brake on a European scrapyard, older retarders might be easier.

Exhaust brakes have been available for decades, might be able to find one in a scrap yard. They are not engine specific. The exhaust valve springs on a multifuel are strong enough for a exhaust brake.

Jake brakes are engine specific and none are made for a multifuel. Only engines that they are made for are used in class 8 trucks (18 wheelers) so 10 liter and larger motors. Everything smaller uses a exhaust brake.

 

[Robo McDuff]

I am putting a pac brake on my M932A2.

Just checked what that means. The pressure-regulated version (works also at lower rpm) or the fixed hole version (a lot cheaper but works only good at higher rpms)

 

[73m819]

You might want to look into Russian military vehicles, the have used some sort of auxiliary braking for a long time, even on there big 12 cyl. multi.

Another idea for the auto trans trucks, is to install a retarder, basically just replace the twin vane converter with a four vane converter (a double sided veined disk between the two halves of the converter, of course there is more to the install but if you have a big truck auto, most times you can find a retarder converter for it.

 

[grendel]

Just checked what that means. The pressure-regulated version (works also at lower rpm) or the fixed hole version (a lot cheaper but works only good at higher rpms)

Pressure regulated with an over ride switch.

 

[wcuhillbilly]

I love Jakes,,,, Jacobs Brake,, I jaked my 36,000 lbs 816 wrecker with a 3 stage jake, meaning that stage one activates the jake on one head, stage two does two heads, stage three kicks in the last head, -855 cummins (the 250nhc that is in our 5 ton trucks) segmints the head for the engine into 3, individual heads housing 2 cylinders each.
The Jake is by far the best for the big engines, you would have to source civilian truck parts to make the swap and likely wire in a voltage reducer from 24vdc to 12 vdc depending on your countrys standards. Like mentioned earlier,,, each jake is engine specific and some engines do not have a jake available, once bolted on they become an integral part of the engine and if the truck was not designed for it, you may have to modify the existing sheetmetal of the truck.. I did, look up "816 Jakes and Turbo" in the hotrodding 5 ton section.....
The smaller engines will likely lead you to the exhaust brake AKA pacbrake which is nothing more than a vacuum or air actuated butterfly valve in the exhaust pipe. this kind can be added to any existing pipe and only requires enough surrounding space to cut out some pipe and install this valve and associated tubing to actuate. very simple and very cost effective. Becoming a standard option on most 1 ton pickup trucks with diesel engines here in the states. I have retro fitted a few onto older diesel engines, only draw back is they create some back pressure on the valves, so increase the valve spring strength when you install one of theses. I believe a multi fuel would do just fine in the non industrial/non commercial realm... basically it will serve you well in the hobby world. The exhaust brake doesn't work as good or quickly as the Jake, but they do work very well. I have modified mine by welding up the bypass hole in the butterfly plate and shortening the actuation arm slack to make a more restrictive, positive engagement. Folks have ridden in my truck and asked how my brake feels so much more stronger than the identical one on their same make model of truck/brake. I then explain my modification. The exhaust brake does work at lower RPMs just not as well, a Jake will almost stall an engine out because it is releasing compression from the cyl, an exhaust brake forces more back pressure on an engine, thus making it hard to breathe, thus it is not going to stall the engine very well.

The "Brake Saver" is another option that is rare but extremely effective, however I doubt it is very common on the smaller diesels. I have run them in big Peterbilts/freightliners, Volvo/White. They basically put a retarder that is activated by engine oil in the bellhousing of the trans and upon activation dumps a few extra gallons of hydraulic resistance into that retarder housing effectively slowing the driveline down without the annoying noise associated with the Jake brake. Electric retarders are similar but rely on magnetic activation by electric and a location on the driveline.

Another option is to split the master cylinder. Mount a second master cyl next to your existing one and modify the actuation arm/rod so that it will actuate both mastercylinders at the same time. Put rear axles on one cyl and the fronts on another, This was done in the 1960s with the big trucks until they combined the mastercylinders into dual reservoir cylinders with proportioning valves. Lastly,,, Air brake conversions.... but this opens up another can of worms....

 

[Robo McDuff]

I think the picture is getting clearer.

Let's ignore the 900 series. It's a completely different beast, an older modern truck, while the M39 and 800 series are basically newer old trucks. Anyway, the 900s have auto trans and mostly already a retarder installed (if not connected).

However nice, a Jake Brake is out also. Never made for these old trucks, would be too costly in engineering and a problem with noise.

That leaves the cheap and dirty exhaust brake alternative as the cheapest and easiest to do. Not sure how they work on an old multi fuel though.

Or electric or hydraulic retarders. Sweet but probably rather expensive and not that simple to install. Maybe with the low-powered multi fuel (175 HP) connecting an electric retarder to a permanently engaged PTO might be the best. The M51 has two of them. Problem is the cooling and the need for additional juice, maybe extra high-quality batteries?

We are going to work on the truck this spring (fingers crossed, famous last words etc) and making a double circuit is second on the list. The retarders are an extra to that; we have some small but steep hills around us.

 

[gimpyrobb]

The multifuel in a deuce and a multifuel in a 5ton are no different. If you read Bjorns exhaust brake install, you know all you'll need to know.

 

[74M35A2]

Few other options, feel free to take the good ideas or just shoot them all down, but it is fun to think creatively:

-An SS member in OH is swapping out his juice 5T axle ends for those from an M939 series, so going to air brake. I don't think he has started yet, and thanks grendel for the parts. Could do this? Could gain CTIS same time if wanted. People are now running CTIS full manual successfully, so it may regain popularity.

-Refresh your brake system completely from booster to wheel cylinders, it "should" hold well for a long while, especially with updated coated or stainless lines. It did work well when new as intended, has anybody actually experienced failure on relatively new parts?

-Truck should be 5 speed manual? Forced downshifts will help to slow if you have distance ahead to do so, like compression or exhaust braking.

-Reman the parking brake so it would have maximum effectiveness to be used when rolling, if need be. Not much, but every bit would help.

-Add a pinion brake to one of the rear axles, with it's own activation circuit/pump. This would effectively make your brake system dual circuit for emergency use only. You could use an automotive ABS pump and a dash mounted switch to activate it. I don't think these are strong enough to lock up once moving at high speed? I have no experience with them, but it would work very well compared to a busted open single circuit system, that's for sure. If they are relatively weak, then add one on each rear axle. Ask the monster truck guys if they are any good at slowing down built up speed, I have no idea. This is the path I would go, it is completely independent, and relatively low cost. Even better than "dual circuit", a true "emergency brake".

For those not in the know, Jake brake and exhaust brake are 2 different things. Jake brake forces the engine to act like an air compressor, and exhaust brake is just throttling the exhaust pipe closed. Exhaust brake has limited effectiveness compared to Jake brake, but it still does something over nothing, and is relatively low cost. Effectiveness is reduced with reduced RPM. I have not seen anybody confuse these two here though.

 

[gimpyrobb]

Pinion brakes are no good for trucks that are street driven. The pinion spins 6 times faster than the axles. That creates so much heat you will burn up at least the brakes if not the axle housing.

 

[74M35A2]

OP was worried about single circuit failure. Would the pinion brake not work even a single time to prevent him from hitting something? I think it is a perfect emergency brake.

 

[red]

OP was worried about single circuit failure. Would the pinion brake not work even a single time to prevent him from hitting something? I think it is a perfect emergency brake.

Pinion brake would work for that 1 emergency stop from highway speed. Warp the rotor but that's better than not stopping. Can mount up to 4 pinion brakes on the rear axles (never the front axle). Bad idea to plumb it in to automatically engage, leave it as a separate system.


With air brake conversions I'm doing that to my m816 wrecker as well.

 

[gimpyrobb]

From the folks I've spoken to that have used pinion brakes, they will burn up on a street driven truck. Even though there is minimal drag, the fact that it spins 6 times faster is what creates the heat and damage.

I've never seen them in person so I cannot speak with much authority.

 

[red]

Guessing that the folks you've talked to are running pinion brakes on mud boggers or rock crawling vehicles? Their setup is designed differently, meant to serve as the service brakes so it uses hydraulic calipers (usually 80's era chevy 1/2 ton pickup calipers) which maintain contact with the rotor even when the brakes are not applied. Pinion brakes that are meant to be used for parking or as a emergency brake will run with either a cable or air actuated brake caliper which pulls the pads away from the rotor completely.

 

[Robo McDuff]

OP was worried about single circuit failure. Would the pinion brake not work even a single time to prevent him from hitting something? I think it is a perfect emergency brake.

Correct, but as mentioned earlier, we are going to dual the circuit regardless, and as number two priority. If I have the whole truck up and am messing around, might as well add some kind of retarder as a nice extra to help regular brake action in our hilly entrance into town. However, I do not consider the retarder, certainly not an exhaust brake, as the thing to save my neck (and live) in case of a catastrophic brake failure.

As to catastrophic brake failure, I think one or two members had good maintained systems that failed, and I know from other oldtimers and normal cars that blown seals and ruptured flex brake lines do happen also on well-maintained or even new systems.

With a dual system or a small passenger car, mostly you can handle it (if you are lucky). With an old truck weighing 10 tons, not so much. Besides, even the smallest problem connected with me not braking quick enough will automatically shift a lot of attention to me, regardless if somebody else was the cause of the accident or not.