Towing with a 200-series Toyota Land Cruiser (2 Viewers)

[tincan45]

Don't be afraid to use 2nd gear on a steep downhill. It won't hurt your engine to rev 5000 RPMs. Use your brakes sparingly to control your speed as needed but if you're riding them you need to slow down a use a lower gear.

Turn your trailer brake controller up. I usually run around ~6 on my redarc but I'll crank up to 8+ on a steep descent. Too high trailer brakes are not ideal for emergency maneuvers but don't hesitate to use them. I don't manually activate mine hardly ever but YMMV.

Yes - I find it rare to get out of S4 even on long trips. S2 and S3 (on 6 speed trans) are normal on long grades, both up and down. Look like you might have a 8 speed so I don't know how that translates. The 5.7 seems like it really hits it's stride at around 4K and has no problem humming away at that speed.

I also have the redarc, and I assume they all tune differently. I run mine around 2-3 and 4 on the steep downhill grades. Above 5 I get lock ups. You will be surprised how small adjustments make a big difference.

 

[2021 LC200]

A couple of thoughts on downhill breaking with a trailer or even vehicle alone:

- Slower or taking it easy is better and when applying brakes do it for a shorter duration harder
- The 200 series brakes are pretty good by design as they also allow for prolonged offroad A-TRAC application
- In case of a heavy trailer probably limit to S2, maybe even S1 if there is not much other traffic
- The revs on the engine to allow for efficient engine breaking, my experience is around 3000 to 4000 rpm. Once over that it tends to take off to 5000/6000 rpm and you definitely need to apply brakes.
- It appears to me the braking on the engine revs coincide with higher torque output by the engine or in other words, the airflow is most efficient through the engine (best fill pressure due to engine manifold design and standing wave affect). My experience with the throttle closed it appears providing most resistance as well. For the 3UR-FE max torque is around 3500 to 3750 per the purple graph below and posted engine specs on the internet.

So all in all I would once getting above 4000 rpm apply brakes to drop down to 3000 rpm and if that is becoming too quick a cycle brake more and shift down one (say S3 to S2 or S2 to S1) while braking (so the brakes take most of the load and not the transmission), then go back staying between 3000 to 4000 rpm, brake to 3000 and let it run up again to 4000 rpm. Apply extra braking for corners ofcourse . And after corners when possible going real slow let the speed slowly build up again to 4000 rpm giving the brakes more time to cool down. Since I am a MSc mechanical engineer I do this automatically as it makes sense to do it this way.

I would not engine brake at 5000 to 6000 rpm as it is in my experience not braking much and just puts a lot of high rev reverse loading on the engine.

Interested to hear further thoughts on optimum engine braking rpm.

 

[linuxgod]

Yes - I find it rare to get out of S4 even on long trips. S2 and S3 (on 6 speed trans) are normal on long grades, both up and down. Look like you might have a 8 speed so I don't know how that translates. The 5.7 seems like it really hits it's stride at around 4K and has no problem humming away at that speed.

I also have the redarc, and I assume they all tune differently. I run mine around 2-3 and 4 on the steep downhill grades. Above 5 I get lock ups. You will be surprised how small adjustments make a big difference.

6 speed, but I'm geared with 4.88s. Prior to that I never drove above 4th.

FWIW 5th gear w/ 4.88s gets me a little less RPM than 4th with 3.90 gears, but overall MPG on my trips is within ~5% I think.

 

[linuxgod]

I'd be cautious on this without prior testing on the specific vehicle/trailer combination. Brake sensitivity can vary between trailers.

Just a few weeks ago I was pulling my trailer out of my driveway, and had the trailer breaks lock up and suddenly yoink my LX backwards after the slightest application of brakes on the LX. Turns out I had accidentally changed the RedArc's setting from my usual 4-4.5 to 8 while cleaning the vehicle. I'd hate to have that level of brake application in a non-emergency road situation.

Yes definitely something to test beforehand. I've found even with mine set acceptable sometimes by the time I get near home on city streets if I hit the brake a bit too hard I'll lock my trailer brakes up to a screeching halt. Seems like as they get hotter sometimes they get more sensitive?

 

[linuxgod]

A couple of thoughts on downhill breaking with a trailer or even vehicle alone:

- Slower or taking it easy is better and when applying brakes do it for a shorter duration harder
- The 200 series brakes are pretty good by design as they also allow for prolonged offroad A-TRAC application
- In case of a heavy trailer probably limit to S2, maybe even S1 if there is not much other traffic
- The revs on the engine to allow for efficient engine breaking, my experience is around 3000 to 4000 rpm. Once over that it tends to take off to 5000/6000 rpm and you definitely need to apply brakes.
- It appears to me the braking on the engine revs coincide with higher torque output by the engine or in other words, the airflow is most efficient through the engine (best fill pressure due to engine manifold design and standing wave affect). My experience with the throttle closed it appears providing most resistance as well. For the 3UR-FE max torque is around 3500 to 3750 per the purple graph below and posted engine specs on the internet.

So all in all I would once getting above 4000 rpm apply brakes to drop down to 3000 rpm and if that is becoming too quick a cycle brake more and shift down one (say S3 to S2 or S2 to S1) while braking (so the brakes take most of the load and not the transmission), then go back staying between 3000 to 4000 rpm, brake to 3000 and let it run up again to 4000 rpm. Apply extra braking for corners ofcourse . And after corners when possible going real slow let the speed slowly build up again to 4000 rpm giving the brakes more time to cool down. Since I am a MSc mechanical engineer I do this automatically as it makes sense to do it this way.

I would not engine brake at 5000 to 6000 rpm as it is in my experience not braking much and just puts a lot of high rev reverse loading on the engine.

Interested to hear further thoughts on optimum engine braking rpm.


View attachment 3698013

Nice insight. I don't necessarily worry about revving and there's still a lot of engine braking up around 5k RPMs but to be fair I try not to run that high because if you start to build speed you'll approach redline pretty quickly. I hadn't specifically noticed less engine braking at 5k RPMs but next year when I'll flying through the rockies again with the trailer I'll pay more attention

Something in that graph seems off to me. I thought HP and torque were the same at 5250 RPMs, and also that we maxed out at about 400 ft lbs of torque? Is left Y axis HP and is there a missing secondary Y axis with different values for torque?

 

[2021 LC200]

Something in that graph seems off to me. I thought HP and torque were the same at 5250 RPMs, and also that we maxed out at about 400 ft lbs of torque? Is left Y axis HP and is there a missing secondary Y axis with different values for torque?

Power (torque x rpm) is shown in kW and torque in Nm. Just a graph i picked up from somewhere else in IH8MUD. Per legend, it also has the diesel graphs on there so do not confuse.

Separate search shows 3UR-FE max torque is at 3600 rpm, so two sources pointing the same direction.

I appreciate your insights from a next decent and using engine breaking. I have noticed this on other vehicles as well (the engine braking "hump") so I am a believer, as you do when you think you understand something. I kind of think there is a logic to it. I did graduate as an MSc Mech Eng on LPG injection into a 4 stroke engine, using single point injection timed such liquid petroleum gas would be injected in the right "batch" of air coming by for each cylinder. Did a bunch of fluid dynamic modelling based on pressure wave equations. I am just not sure though regarding this case (i.e. best engine brake action around max engine torque). One change is the inlet throttle is closed vs part or fully open under normal driving.

Let me search the internet some to find any such reference or ideally testing or research around the same. If I find I will share.

I have seen folks on this forum who have tuned engines (like teckis300) who may have insights around this matter. That is an invite...

 

[GordJ]

A couple of thoughts on downhill breaking with a trailer or even vehicle alone:

- Slower or taking it easy is better and when applying brakes do it for a shorter duration harder
- The 200 series brakes are pretty good by design as they also allow for prolonged offroad A-TRAC application
- In case of a heavy trailer probably limit to S2, maybe even S1 if there is not much other traffic
- The revs on the engine to allow for efficient engine breaking, my experience is around 3000 to 4000 rpm. Once over that it tends to take off to 5000/6000 rpm and you definitely need to apply brakes.
- It appears to me the braking on the engine revs coincide with higher torque output by the engine or in other words, the airflow is most efficient through the engine (best fill pressure due to engine manifold design and standing wave affect). My experience with the throttle closed it appears providing most resistance as well. For the 3UR-FE max torque is around 3500 to 3750 per the purple graph below and posted engine specs on the internet.

So all in all I would once getting above 4000 rpm apply brakes to drop down to 3000 rpm and if that is becoming too quick a cycle brake more and shift down one (say S3 to S2 or S2 to S1) while braking (so the brakes take most of the load and not the transmission), then go back staying between 3000 to 4000 rpm, brake to 3000 and let it run up again to 4000 rpm. Apply extra braking for corners ofcourse . And after corners when possible going real slow let the speed slowly build up again to 4000 rpm giving the brakes more time to cool down. Since I am a MSc mechanical engineer I do this automatically as it makes sense to do it this way.

I would not engine brake at 5000 to 6000 rpm as it is in my experience not braking much and just puts a lot of high rev reverse loading on the engine.

Interested to hear further thoughts on optimum engine braking rpm.


View attachment 3698013

Thats interesting because when I took my air brake course they said that was proven that gearing down so that a constant 10 lbs of brake pressure was the best method of descent. The instructor said that speeding up and braking was not optimal and a constant light pressure maintained the best heat dissipation. Of course they also said to go down the hill in the same gear that you went up it. Not everything translates I guess.

 

[2021 LC200]

Thats interesting because when I took my air brake course they said that was proven that gearing down so that a constant 10 lbs of brake pressure was the best method of descent. The instructor said that speeding up and braking was not optimal and a constant light pressure maintained the best heat dissipation. Of course they also said to go down the hill in the same gear that you went up it. Not everything translates I guess.

Which air brake course is this? For 18 wheelers? Interested to hear more. I am sure there is a logic to that keeping 18 wheelers under control. Please share what you know and why.

Edit - Diesels in 18 wheelers and vehicles including the 200 series 1VD 4.5lts turbo diesel tend to have little engine brake action because the typically do not have a throttle (speed is controlled by amount of diesel injected) and peak torque is at the lower end so they get past the "hump" and in lower torque territory pretty quick. That is why 18 wheelers have exhaust brakes. They probably work best at a certain rpm range so that may explain the advised constant breaking to keep speed constant.

The logic for shorter harder breaks in passenger vehicles vs prolonged light breaking is to:
- slow yourself down more
- then let the engine brake action keep it within reason, as driving wind cools the brakes down again

Searching on the internet it points in the same direction.

 

[TeCKis300]

This is probably child's play for you guys who do the Rocky Mountains...

So far we've been blessed with fairly flat towing. However our return trip from Wellesley Island NY has us staying at a small campground that has some rather steep approaches. At least they seem steep to me.
Going uphill on this run to the campground doesn't bother me a bit as it looks like a pretty nice road with good shoulders.
But what's the advice for downhill on the return?

My plan is to:

• GO SLOW
• Dial up the Tow Pro Elite from 3.5 for level to about 4.5 or more
• Downshift from S6 to S4 or perhaps lower
• Try not to ride the brakes
• Stay ready to push the button for manual braking

Do I have this close to right?
Any thoughts?

Here's the elevation profile for the run I'm concerned about, starting at the highest point:
View attachment 3697948

I think the guys covered it. 12.9% can be spicey depending on how heavy the trailer is. If the rig is accelerating with engine braking, don't hesitate to apply brake and grab the next gear down for more engine braking. There's no limit, use as low of a gear and as high of rpm to hold the rig from feeling like a runaway freight train. Don't try to manage that momentum on axle brakes alone as that can and will overheat them. You won't need to, and the 8-speed has more and deeper lower ratios to better manage engine braking, but at altitude and very very steep grades, I've even used low range. When using extreme engine braking, if the trailer is heavier than the tow vehicle and leaning on it for engine braking, it can jackknife the tow rig. So axle brakes are just as important of a tool.

In regards to max engine braking - yes, there is relatively more engine braking per engine revolution at peak torque. But more RPM will ultimately still be doing more work to draw vacuum and compress air, which will result in more engine braking overall. So spin the engine, but as pointed out, be ready to apply brake and grab a lower gear. The max amount of engine braking should track closely to the HP curve with max output/braking @ ~5.5k rpm in a gasser. Diesel brakes work differently. The reason why the torque peak feels strong is that it's more efficient at creating engine braking per RPM, due to better volumetric efficiency (VE) at that rpm. VE means the engine draws in and fills the piston chamber with relatively more air per cycle to compress. But it is not going to result in more overall braking than the HP peak.

One caution to turning up trailer brake gain - the drum brakes on trailers are low tech with little heat dissipation capacity compared to the tow vehicles modern disc brakes. The trailer pads are also low end and will not put up with significant heat. On longer descents, trailer brakes can quickly overheat and fade - well before the tow vehicles brakes which might have upgraded high temp pads. This is why we engine brake after all as to not overheat the physical brakes on any of the axles. It may feel stable to increase gain on the trailer as that keeps the hitch in tension, but it's also a risker proposition with less margin, as it makes axle overheating limits lower when asking the least capable set of axle brakes to work harder. Personally, I leave the brake gain where it is. On really long descents and I'm driving faster than I should towing, I actually turn the gain down (to avoid overheating the trailer brakes), and use as much engine braking as I can.

Agree with @2021 LC200 with technique - Strong stabs of the brake in a straight line, letting up before entering a turn, with a stabilized rig that has shed most of the excess momentum from the trailer.

 

[FrazzledHunter]

I think the guys covered it. 12.9% can be spicey depending on how heavy the trailer is. If the rig is accelerating with engine braking, don't hesitate to apply brake and grab the next gear down for more engine braking. There's no limit, use as low of a gear and as high of rpm to hold the rig from feeling like a runaway freight train. Don't try to manage that momentum on axle brakes alone as that can and will overheat them. You won't need to, and the 8-speed has more and deeper lower ratios to better manage engine braking, but at altitude and very very steep grades, I've even used low range. When using extreme engine braking, if the trailer is heavier than the tow vehicle and leaning on it for engine braking, it can jackknife the tow rig. So axle brakes are just as important of a tool.

In regards to max engine braking - yes, there is relatively more engine braking per engine revolution at peak torque. But more RPM will ultimately still be doing more work to draw vacuum and compress air, which will result in more engine braking overall. So spin the engine, but as pointed out, be ready to apply brake and grab a lower gear. The max amount of engine braking should track closely to the HP curve with max output/braking @ ~5.5k rpm in a gasser. Diesel brakes work differently. The reason why the torque peak feels strong is that it's more efficient at creating engine braking per RPM, due to better volumetric efficiency (VE) at that rpm. VE means the engine draws in and fills the piston chamber with relatively more air per cycle to compress. But it is not going to result in more overall braking than the HP peak.

One caution to turning up trailer brake gain - the drum brakes on trailers are low tech with little heat dissipation capacity compared to the tow vehicles modern disc brakes. The trailer pads are also low end and will not put up with significant heat. On longer descents, trailer brakes can quickly overheat and fade - well before the tow vehicles brakes which might have upgraded high temp pads. This is why we engine brake after all as to not overheat the physical brakes on any of the axles. It may feel stable to increase gain on the trailer as that keeps the hitch in tension, but it's also a risker proposition with less margin, as it makes axle overheating limits lower when asking the least capable set of axle brakes to work harder. Personally, I leave the brake gain where it is. On really long descents and I'm driving faster than I should towing, I actually turn the gain down (to avoid overheating the trailer brakes), and use as much engine braking as I can.

Agree with @2021 LC200 with technique - Strong stabs of the brake in a straight line, letting up before entering a turn, with a stabilized rig that has shed most of the excess momentum from the trailer.

Thanks for commenting. This is helpful as were the other posts.
I should have stated the weights. We weighed our trailer & LC with an actual load in the trailer and a simulated load in the LC (2 passengers, full tank of gas and lots of junk in the cargo bay). We weighed in a 5400# trailer and 7000# LC. We expect that to be our actual loads towing. We have a REDARC Tow Pro Elite which has been awesome so far. We also have DBA & Hawk rotors/pads and Slee stainless brake lines. The hitch has the LC absolutely level.

The brake gain has me a bit puzzled - so I thought I'd increase it somewhat. I was a bit concerned about manual braking and had visions of smoking trailer brakes!

I have no idea the quality of brakes on the trailer - all I can say is that there is very few miles on the trailer so far (815 miles to be exact LOL) so I hope the brakes are in good shape. I plan to have the brakes looked at this fall at a highly regarded local RV shop if for no other reason than to find out the quality.

Are there better brake pads for trailers then what typically comes from the factory? If so I'll unhesitatingly have them replaced this fall with something better just as I did with the LC's rotors & pads which were in perfect shape.

 

[GordJ]

Which air brake course is this? For 18 wheelers? Interested to hear more. I am sure there is a logic to that keeping 18 wheelers under control. Please share what you know and why.

Edit - Diesels in 18 wheelers and vehicles including the 200 series 1VD 4.5lts turbo diesel tend to have little engine brake action because the typically do not have a throttle (speed is controlled by amount of diesel injected) and peak torque is at the lower end so they get past the "hump" and in lower torque territory pretty quick. That is why 18 wheelers have exhaust brakes. They probably work best at a certain rpm range so that may explain the advised constant breaking to keep speed constant.

The logic for shorter harder breaks in passenger vehicles vs prolonged light breaking is to:
- slow yourself down more
- then let the engine brake action keep it within reason, as driving wind cools the brakes down again

Searching on the internet it points in the same direction.

The short story is that the easiest way to stop momentum is to not let it build. Braking harder to slow down heats the brakes more than lighter braking that slows momentum. Air is a lousy medium to transfer heat and trying to get rid of brake heat by coasting between brake applications is not terribly effective. When you come up to a stop sign do you wait until the last minute and brake hard to save the brakes? I tend to slow down easily and use engine back pressure to stop. If you double the weight the stopping distance doubles and if you double the speed the stopping distance quadruples. Light braking that keeps speed down is more efficient.

 

[2021 LC200]

The short story is that the easiest way to stop momentum is to not let it build. Braking harder to slow down heats the brakes more than lighter braking that slows momentum. Air is a lousy medium to transfer heat and trying to get rid of brake heat by coasting between brake applications is not terribly effective. When you come up to a stop sign do you wait until the last minute and brake hard to save the brakes? I tend to slow down easily and use engine back pressure to stop. If you double the weight the stopping distance doubles and if you double the speed the stopping distance quadruples. Light braking that keeps speed down is more efficient.

Well, this does not make sense to me and I would like to understand the logic.

And air does cool brakes, no doubt.

This is why some performance vehicles duct air to the brakes and we have the air ventilated style typically on the front axle.

Also reading up on truck drivers on descending from significant grade, they do understand brakes will fade by continuously applying brakes.

Again if that does work different for 18 wheelers, I like to understand as the principles for passenger vehicles or passenger vehicle + trailer are all very similar.

Now going slow downhill in low gear to prevent issues, that is certainly the way to keep things manageable as once you go above the system capability you become a run away vehicle.

 

[GordJ]

Well, this does not make sense to me and I would like to understand the logic.

And air does cool brakes, no doubt.

This is why some performance vehicles duct air to the brakes and we have the air ventilated style typically on the front axle.

Also reading up on truck drivers on descending from significant grade, they do understand brakes will fade by continuously applying brakes.

Again if that does work different for 18 wheelers, I like to understand as the principles for passenger vehicles or passenger vehicle + trailer are all very similar.

Now going slow downhill in low gear to prevent issues, that is certainly the way to keep things manageable as once you go above the system capability you become a run away vehicle.

I’m not sure why this is such a point of contention. For one, I didn’t say that air doesn’t cool. I said that it isn’t efficient. Take a hot piece of metal, say after heating it with a torch to free a bolt, and wave it around for a while and then dip it in water. Which cools it faster? My point is that a light application, constantly applied, keeps the heat from building more efficiently than allowing speed to build and then brake more aggressively to slow the momentum. Remember, when braking, speed kills. At least that is what the government licensed driving school instructor taught in his course.
Of course to be able to descend with a light application of brakes one has to be in a low enough gear that engine braking is doing most of the work.
And when doing your internet research you should try and differentiate between the different causes of “brake fade” because most large vehicle loss of braking, historically, seems to be caused by aggressive braking depleting air pressure faster than compressors can replenish and not just overheating brake drums. Heavy braking requires more air. Again, which can be avoided by correct gear selection and light application of brakes. Of course this is just my experience, you do you and I’ll do me.

 

[linuxgod]

I’m not sure why this is such a point of contention. For one, I didn’t say that air doesn’t cool. I said that it isn’t efficient. Take a hot piece of metal, say after heating it with a torch to free a bolt, and wave it around for a while and then dip it in water. Which cools it faster? My point is that a light application, constantly applied, keeps the heat from building more efficiently than allowing speed to build and then brake more aggressively to slow the momentum. Remember, when braking, speed kills. At least that is what the government licensed driving school instructor taught in his course.
Of course to be able to descend with a light application of brakes one has to be in a low enough gear that engine braking is doing most of the work.
And when doing your internet research you should try and differentiate between the different causes of “brake fade” because most large vehicle loss of braking, historically, seems to be caused by aggressive braking depleting air pressure faster than compressors can replenish and not just overheating brake drums. Heavy braking requires more air. Again, which can be avoided by correct gear selection and light application of brakes. Of course this is just my experience, you do you and I’ll do me.

Light may be more efficient than heavy braking but any continuous braking over a long descent will eventually cause the brake fluid to boil. If you’re light braking for miles, the friction will continually heat the brake fluid, just ask my wife who years ago left a parking brake lightly set on an old car of ours and drove about 15 minutes on a flat highway… then promptly had no brakes on the off ramp.

 

[2021 LC200]

Sorry GordJ, I do not get the logic of continuous braking and the reasons described.

Also the point about air I do not get. With no air (i.e. vacuum) brakes would continuously heat up. That would lead pretty rapidly to fading and brake fluid boiling and uncontrolled acceleration. The example mentioned above about air cooling down a heated bold in water better, i have to agree for that case, yet we do not normally drive down a river as we come down the mountains, do we...? Air is our only friend to control brake temperatures and our vehicle speed is a friend of the same.

The advice of continuous braking is dangerous as a) it will heat up the brakes and brake fluid continuously (and there is no gauge to tell you what is going on) and b) you would not know if there is a balance between engine braking and applying the regular brakes. By intermittent braking you know you have to slow down if the engine braking action is not sufficient. This would be exactly the same for 18 wheelers.

Now can you do what is being proposed (continuous braking), maybe? Materials and capabilities and the size of brakes and brake fluid have improved over the years. I am sure a significant improvement in that area over say 50's or 60's cars. I would not count on it though. Same for truck drivers.

Now 18 wheelers are running a business and time is money. It maybe that exhaust brakes + modern oversized regular brake systems can maybe be used and pushed differently. Still find that scary as a participant on the road.

Happy I use my mirrors a lot as part of the way I drive so I typically know what is going on behind me as well.

 

[2021 LC200]

Light may be more efficient than heavy braking but any continuous braking over a long descent will eventually cause the brake fluid to boil. If you’re light braking for miles, the friction will continually heat the brake fluid, just ask my wife who years ago left a parking brake lightly set on an old car of ours and drove about 15 minutes on a flat highway… then promptly had no brakes on the off ramp.

Correct and I have also seen a case of a parking brake being applied leading to overheated brakes and a loss of the system with expensive repears. My father did this in his 60's car when many did not have a warning light let alone a buzzer yet. Luckily this was on flat roads with front brakes still working.

 

[2021 LC200]

This pretty much confirms on long downhill grades to make sure a) use engine breaking and b) use brakes intermittently to control speed aka snubbing.

Definitely not continuous braking. See around min 4:30



Shocking what was thought to GordJ by the government licensed driving instructor, in fact criminal, as continuous brake application on long downhill grades almost certainly leads to a run away and a major deadly type accident endangering other road users as well.

 

[TeCKis300]

This pretty much confirms on long downhill grades to make sure a) use engine breaking and b) use brakes intermittently to control speed aka snubbing.

Definitely not continuous braking. See around min 4:30



Shocking what was thought to GordJ by the government licensed driving instructor, in fact criminal, as continuous brake application on long downhill grades almost certainly leads to a run away and a major deadly type accident endangering other road users as well.

Snubbing. I learned a new term today. I like it.

 

[GordJ]

This pretty much confirms on long downhill grades to make sure a) use engine breaking and b) use brakes intermittently to control speed aka snubbing.

Definitely not continuous braking. See around min 4:30



Shocking what was thought to GordJ by the government licensed driving instructor, in fact criminal, as continuous brake application on long downhill grades almost certainly leads to a run away and a major deadly type accident endangering other road users as well.

like I said, you do you and I'll do me.

 

[2021 LC200]