Outer Limits 4x4 Board

Just curious if a jake brake would be of use on a auto 4by to assist with decents?????

Has anyone tried this?

Thoughts?

Nev62 wrote:Just curious if a jake brake would be of use on a auto 4by to assist with decents?????

Has anyone tried this?

Thoughts?

Jacobs is actually a brand but is what most refer to when talking about an engine retarder.

I think you mean an Exhast Brake not a Jacobs brake. If you are sure you mean a Jacobs brake do you actually understand how they work?

I have heard of people using exhast brakes in deisel auto 4wds when towing heavy loads. It would work well going down a hill at road speed but just idling down a hill in a 4wd situation i dont think you will have the exhast flow to slow the engine.

Some info on a Jacobs brake for those that dont understand the difference-

The Jacobs Engine Brake® is a device that mounts on, or within, the engine overhead. It changes the timing of the engine exhaust valves, turning the engine into a giant air compressor. The resulting retarding power is proportional to engine RPM (always stay within engine manufacturers recommendations). It is typically used on heavy-duty vehicles commercial vehicles ("big rig" trucks and buses) enabling safer vehicle speed control in several driving conditions, from flatlands to steep downhill descents. The result is increased productivity (thus profitability) from shorter trip times (faster downhill control speeds), and reduced maintenance costs and downtime (from reduced use of the foundation braking system).

Here is the info on an Exhast brake and how it works-

Unlike gas engines, diesel engines produce no vacuum when you lift your foot off the throttle. Even without fuel, the engine takes in air, compressing it in the cylinders and continuing to power the vehicle. The Jacobs Exhaust Brake® mounts in the exhaust system of the vehicle, and restricts exhaust flow when activated. This supplementary braking system helps to slow your vehicle. This slowing power is achieved by restricting the flow of exhaust gases and increasing backpressure inside the engine. This increased backpressure creates resistance against the pistons in your engine, slowing the crankshaft's rotation and thereby slowing your vehicle. Overall, you use your service brakes less, they last longer and save you money.


Generaly big trucks run Jacobs brakes and small trucks run exhast brakes.

Ruff, yeah I did mean an exhaust brake and did know the difference (used to drive trucks for a living). I don't think they make a jake brake for a GM motor anyway.

Many moons ago, I remember a company in the snow fields using exhaust brakes on their people mover 4x4s. I know from driving semi's that the jake brake did not do a lot the last few KMH but was thinking more of stoppin an auto from running away on a step grade when wheeling (more to keep the speed in check than for stopping).

Well I did not know of the 2 types or how they worked.
Cheers for the info Ruff.

found this add in a verry old 4wd monthy my dad came across at work and brough thome for me to read..

its fro an exhaust brake system, australian owned and manufactured, comes in easy to fit form, air vacuum opperated, fits all diesel veichels.

ONLY $ 1190 inlcuding GST

from EBS enginnering, po box 25b bungalow cairns QLD 4870

free call 1800 632 611 or phone/fax - (07) 4035 5611

thats about it...

Or duck off to a truck wrecker and pick one up off an old Dyna and slot her in.

Just hook it up to your exhauster and rig up a switch to your cab. Or cable it if you're lazy. No good for low speed though. Only for hill descent towing on the highway.

Nice explanation Tony ,

currently driving a little NPR350 st 170 TBi , with an auto ,
Its still fitted with the exhaust brake , You can get some braking from
the exhaust brake as long as the revs are well over the stall speed of the auto trans converter , its un reliable braking though it will fall into free fall at any time , but still worth using ( 35,000 ks first set of rear linings )

I don’t think they are called jake brakes any more, their Cummins brakes as Cummins brought the name, company, product or something??

Dozoor wrote:Nice explanation Tony

Thanks but i Bogged it from the Jacobs Vehicle Systems site

Bogged It

If you want to do this all you need to do is go and get an exhaust brake valve off a wrecked jap truck, say a Toyota Dyna or something like that, all the jap trucks run the same set up. Its only the likes of Cummins, CAT and Detroit that run Jakes and they can't easily be adapted to any old engine, there is no comparison between an engine brake and an exhaust brake, engine brake wins hands down. Personally I think you're better off holding an open hand out the window than bothering with an axhaust brake, or try two hands and make it interesting!

dromana7411 wrote:found this add in a verry old 4wd monthy my dad came across at work and brough thome for me to read..

its fro an exhaust brake system, australian owned and manufactured, comes in easy to fit form, air vacuum opperated, fits all diesel veichels.

ONLY $ 1190 inlcuding GST
from EBS enginnering...

they been advertising them for years... never seen one on a 4b yet...

I met a chippie once who had fitted an exhaust brake from a truck to his 75 series cruiser. He said it worked well and didn't cost much from the wrecker. I think he needed it as his cruiser was usually about 3.5 tonne with all the gear he had on it.

I have driven mitsubishi canters and ford traders fitted with exhaust brakes and they do work, U cant just slam them on to stop u instead of using the brakes, they have the same affect as changing down a gear.