1HD-T 5 Speed or 1HD-FT Auto

[cmjtaco]

If you had only those two options, which would you pick, and why?

I'm currently living in Japan as a service member, and am about to buy a 1HD-FT Auto cruiser, due to how rare the manuals are. There are a couple 1HD-T 5-Speed's every now and then, and they're expensive. I want a manual, but also want that sweet 24V Turbo Diesel power. Why, Toyota! Why did you not make more manuals in the Japan market!?

Interested to hear your arguments for both!

 

[SaturnAscends]

I'd look for a 5 speed over there. The only reason I have the auto is it was the only way they offered the 80 series here, I miss driving a manual everyday.

@mudgudgeon and @Nemesis1207 might help fill you in on the driving experience of a RHD 5 speed 80 series.

 

[mudgudgeon]

5 speed all the way.

theres not a lot of difference performance wise between 1hd-t and 1hd-ft.

even when hotrodded with upgraded turbo's, tuned fuel pumps, custom exhaust etc, the hd-ft only has a slight advantage, and it's mostly at higher RPM, so not that useful in a diesel.
there is benefits, but engine wouldn't necessarily be the deciding factor for me.

tuned up 1hd-t 5 speed can be a lot of fun to drive

 

[DivByZero]

5 speed hands down. Rather than lay a case for the "why", I'll just ask, does anyone know anybody who's owned a manual 80 series who would pick an auto instead? I'm sure there must be someone out there, but I've never met them.

 

[mudgudgeon]

this is a big part of what i like about a manual.

steep descent, 1st-Low, minimal brake input.

apart fun this, i just find then more engaging and fun to drive

 

[Dusten]

I'd keep my auto. Because I have zero desire to wheel with a stick or sit in traffic with one.

And it's a low revving slow diesel. It's unengaging to drive. I have other toys if I want to be engaged.

 

[PDXTiger]

this is a big part of what i like about a manual.

steep descent, 1st-Low, minimal brake input.

apart fun this, i just find then more engaging and fun to drive

Diesel hardly engine brake, if at all. Big trucks only do it because of devices like a jake brake.

 

[DivByZero]

Diesel hardly engine brake, if at all. Big trucks only do it because of devices like a jake brake.

...Have you driven a manual? I engine brake in my HZJ80 every single time I stop for a light. Every manual vehicle can engine brake.

 

[DivByZero]

I'd keep my auto. Because I have zero desire to wheel with a stick or sit in traffic with one.

And it's a low revving slow diesel. It's unengaging to drive. I have other toys if I want to be engaged.

Is that speaking from experience from owning an 80 series manual diesel or driving one for an extended period, or just guessing based on how you think it'd drive?

 

[PDXTiger]

...Have you driven a manual? I engine brake in my HZJ80 every single time I stop for a light. Every manual vehicle can engine brake.

Curious how you're creating vacuum in your intake mani on a diesel. Unless you have a compression or exhaust brake, or fancy variable geometry modern turbo wizardy, your engine isn't doing anything when you do this.

 

[DivByZero]

Curious how you're creating vacuum in your intake mani on a diesel

You don't need it. In a manual tranny, as you engage the clutch after a geardown, you're transferring the rotational energy from the wheels back through the gearbox into the engine, and forcing the engine internals to spin at a much faster rate than they were at the higher gear. The compression from that process eats power, causing resistance, which is transferred back down the drivetrain and causes resistance at the wheels. You control how much resistance hits the wheels by how much you release the clutch. When the clutch is fully engaged and you've slowed, you switch to an even lower gear and repeat.

I mean, I've been doing this since I learned to drive. In diesels no less, but I've owned and driven petrol manuals too. What experience do you have driving stick?

 

[DivByZero]

*Re-reads posts*

...Ok, I'm coming off as a real dick here. Sorry guys. It's been a s***ty morning.

 

[bug616]

24v auto without a doubt. In my view it is the best engine and transmission combination ever offered in the 80. I sold my built manual 1hdt for an auto just to get away from a manual. Driving lots of twisty hill tracks and roads the manual is a chore. Same in traffic. Auto is much nicer to drive especially off-road and is infinitely better in soft sand. There are some caveats though. The A442F box does not handle heat well and is prone to overheating. Big tyres’s without a re-gear and/or steep hills generate a lot of heat. A big transmission cooler is highly recommended. Manual control in all gears can be added with a valve body and lock-up switch. Manual is definitely simpler with no real issues other than the box being agricultural and worn synchros being a common issue.

 

[PDXTiger]

*Re-reads posts*

...Ok, I'm coming off as a real dick here. Sorry guys. It's been a s***ty morning.

You're fine, no worries. I'm not trying to be or sound like one either, I'm just confused and wondering if I'm misunderstanding something. Auto or manual doesn't really make a huge diff in this equation, you can gear down in both and I've driven just about transmission you can think of short of big truck gazillion gear stuff, and used to be a (non-diesel) mechanic. On a petrol/gas engine, yes, the process you described works because of the vacuum in the intake manifold when the throttle body closes. That is the source of the resistance.

Now, my understanding is that in a diesel, which has no throttle body because everything is based off sucking as much air as possible at all times and controlling engine speed with fueling, there is no vacuum, hence no resistance. You're just spinning the rotating assembly faster, but it's not causing any resistance because it can still freely suck in air. If I am right, which I might not be, my concern is that you're effectively using the friction of a partially-engaged clutch to slow. When I heel-toe a manual gas (petrol) car, that clutch pedal is in and out very quickly to get the full force of the engine braking, but also to prolong the clutch life by not slipping it.

 

[DivByZero]

You're fine, no worries. I'm not trying to be or sound like one either, I'm just confused and wondering if I'm misunderstanding something. Auto or manual doesn't really make a huge diff in this equation, you can gear down in both and I've driven just about transmission you can think of short of big truck gazillion gear stuff, and used to be a (non-diesel) mechanic. On a petrol/gas engine, yes, the process you described works because of the vacuum in the intake manifold when the throttle body closes. That is the source of the resistance.

Now, my understanding is that in a diesel, which has no throttle body because everything is based off sucking as much air as possible at all times and controlling engine speed with fueling, there is no vacuum, hence no resistance. You're just spinning the rotating assembly faster, but it's not causing any resistance because it can still freely suck in air. If I am right, which I might not be, my concern is that you're effectively using the friction of a partially-engaged clutch to slow. When I heel-toe a manual gas (petrol) car, that clutch pedal is in and out very quickly to get the full force of the engine braking, but also to prolong the clutch life by not slipping it.

When the piston is on its compression stroke, both the intake and the exhaust valves are closed in the cylinder. This is the same in both diesel and petrol engines. In diesels however, there's a higher compression ratio because we're relying on heat concentration from the compression of the air rather than a spark to trigger ignition of the air/fuel mix. If either of the valves were open, the air/fuel would be forced out the exhaust or back into the intake on the compression stroke, and if detonation was still able to occur, the force would also exit via the valves as the path of least resistance, rather than forcing the piston down.

 

[kw90surf]

It'll be manual for me. Ever since I swapped my FJ80 it's been so much better to drive, but one of the main reasons is that now I am able to get the most out of my powerplant instead of wasting energy spooling the torque converter and pump in the auto box. As such, economy and power to the ground are increased in a platform that needs as much of those two things as it can get. As well, I appreciate the deeper gearing of the manual box. Have also briefly driven a manual 1HD-T and it's awesome.

Yes, the auto was more point-and-shoot offroad, but I'll take the greater control in all other situations versus advantage in rock crawling or very steep hill climbs. Rowing through the gears in a big beast like the 80 is so much fun.

With regards to the gas / diesel engine braking thing, you're dealing with compression and throttle restriction in a gas engine, and largely compression only in a non-emissions diesel, albeit greater compression. When I removed the emissions-related throttle plate in my diesel Hilux Surf, I noticed my engine braking became less effective, but still not ineffective.

 

[Dusten]

Is that speaking from experience from owning an 80 series manual diesel or driving one for an extended period, or just guessing based on how you think it'd drive?

A diesel 80 no. But numerous diesels in my history yes. I've owned 7 diesels counting my 80.

Add that with owning other low revving, low power vehicles with manuals and I can come up with a pretty good idea.

A diesel manual can be a bear especially because boost drops on each shift. This isn't an issue with an auto.

 

[mudgudgeon]

Curious how you're creating vacuum in your intake mani on a diesel. Unless you have a compression or exhaust brake, or fancy variable geometry modern turbo wizardy, your engine isn't doing anything when you do this.

This has come up before.

I get that vacuum may ceate some engine braking, but think thats only part of the picture.

IMO/ IME diesel provides engine braking through compression at 22:1 (you reference compression braking above).

Having owned both diesel, and petrol 5 speed 80 series landcruiser, and 5 speed diesel 105 series, they absolutely priced engine braking.

A few experiences / scenarios i can think of that illustrate it

Push starting either.

Petrol, get it rolling at a bit more than walking speed, pop the clutch in second gear to start.

Diesel, get it rolling, and speed, pop the clutch in second gear, laugh as you're mate face plants into rear tailgate as the diesel compression stops the truck dead.
Try again, get er rolling, pop the clutch in 3rd or 4th gear to start the engine

Diesel, accidently shift from 4th to 3rd, instead of 4th to 5th, step off the clutch, all four wheels lock up, and you just about kiss the windscreen.

Driving over rough terrain, is hard to keep a steady speed because as your foot lifts off the gas pedal momentarily as you bounce over bumps, the engine brakes as the throttle input is reduced, lurch forward as you go over the bump, engine brake as you bounce off the next one.
Ask anyone who's driven a 12h/12ht manual offroad. Torquey, peaky throttle response, and high compression. They were cursed for it by many a bloke.
Get the right kind of bumps, and you end up bunny hopping over them unless you step on the clutch to stop the lurching.

Driving in traffic in low gears, step off the throttle to suddenly, and a diesel will decelerate dramatically. You have to feather the throttle on AND off.
That deceleration is the result of engine braking.

this is my observations driving various diesel 4x4, and light trucks 3-4 tonne max.
I can't comment about heavy trucks

Teaching my 10 year old to drive a 5 speed diesel landcruiser, the torque off idle was his friend. Made it easy to teach him clutch control. Also was obvious when he eased up on the throttle, to the extent I could coach him to slow down quicky by backing off the gas, knowing engine braking was gonna take care of most of his speed, without stressing about him having to coordinate clutch and hit the brakes.

When my boy got his learners permit, I taught him how to drive on the road in my fzj80. He commented on the difference in feel from my previous diesel cruisers he'd driven.

I taught him to down shift at every intersection or stop light to use engine compression braking so he wasn't relying on brakes. He knew it was nowhere near as effective in the petrol as it was in my diesel cruisers, and questioned the value.

 

[mudgudgeon]

A diesel manual can be a bear especially because boost drops on each shift.

I'll disagree with this too.

In my hdj80, I'd increased boost and increased fuel to bump up the output.
With a 30-40% increase over stock output, it was a lot of fun to drive.

Shift gears at peak power, and yeah, the turbo spools down slightly, but when driving it at slightly above 'Miss Daisy', boost never dropped to zero between gears.

Mine was boosting to 18-22psi, and during shifts boost dropped to around 8-10psi. More than enough to keep a fire lit under it

 

[Dusten]

I'll disagree with this too.

In my hdj80, I'd increased boost and increased fuel to bump up the output.
With a 30-40% increase over stock output, it was a lot of fun to drive.

Shift gears at peak power, and yeah, the turbo spools down slightly, but when driving it at slightly above 'Miss Daisy', boost never dropped to zero between gears.

Mine was boosting to 18-22psi, and during shifts boost dropped to around 8-10psi. More than enough to keep a fire lit under it

That's a specific situation. A majority of diesel Land cruisers aren't turned up.