4.10 Gear Ratio

[stickshifter]

We still don't know the gear ratio in the ring & pinion set. According to an article in Tread, it might be 4.10

INEOS Grenadier: A Closer Look—it’s Not a Land Rover

A Guide to Automotive Adventure & Outdoor .

www.treadmagazine.com

 

[painter]

We still don't know the gear ratio in the ring & pinion set. According to an article in Tread, it might be 4.10

INEOS Grenadier: A Closer Look—it’s Not a Land Rover

A Guide to Automotive Adventure & Outdoor .

www.treadmagazine.com

That's going to help with the tow ratings, and putting on 33's .

Will be very interesting to see what, if any, spec differences there are for Canada/USA (power output and GVWR for two)

Article teases about a LWB wagon, a pick up and a diesel engine. Hah, how long can a fella wait !

 

[Camskii]

We still don't know the gear ratio in the ring & pinion set. According to an article in Tread, it might be 4.10

INEOS Grenadier: A Closer Look—it’s Not a Land Rover

A Guide to Automotive Adventure & Outdoor .

www.treadmagazine.com

4.1 - it's on the website

 

[stickshifter]

4.1 - it's on the website

Hadn't seen that update - thanks!

 

[RoadBuilder]

This would give the Grenadier a crawl ratio (in the gas/petrol version) of 53.8:1 (5.25 first gear in zf8hp51 times 2.5 transfer case reduction times 4.1 differential ratio).

 

[stickshifter]

This would give the Grenadier a crawl ratio (in the gas/petrol version) of 53.8:1 (5.25 first gear in zf8hp51 times 2.5 transfer case reduction times 4.1 differential ratio).

Yup. Anyone who wants to check that math can use this online calculator: https://www.crawlpedia.com/crawl_ratio_calculator.htm

Let's round it to 54:1 for simplicity. That's pretty good. Its an 8-speed transmission, so if that sounds low, don't worry, you can up-shift out of first gear. People who drive very steep inclines and people who spend a lot of time in the rocks will probably feel like it is not low enough. If you spec your order for the lowest gearing possible, you can get crawl ratios of 95:1 from the factory with a Bronco (https://www.hagerty.com/media/news/the-new-broncos-crawler-gear-ratio-is-seriously-impressive/), and 100:1 from the factory with a Jeep Wrangler (https://www.jeep.com/2023/wrangler/capability.html). These very low crawl ratios are what you want if the most important thing to you (off-road) is crawling up and down steep rocky trails. I think most people on this forum will be happy with 54:1 (especially given the 8-speed gearbox).

For some additional comparison, the 2019 and later model Power Wagons have a crawl ratio of 51:1 and the 4-Runner is around 35:1 (those are the only ones I know off the top of my head).

Anyone interested in gearing in old Land Rovers (for comparison) can check out this site: http://www.expeditionlandrover.info/gear_ratio.htm

 

[painter]

Plus with an automatic transmission the effective ratio may be lower if the torque converter allows for some slippage. Power transfer wont be as consistent or linear as with a manual trans tho.

 

[DenisM]

So, at 54:1 low ratio in first gear, and 550Nm torque input... a theoretical 29,700Nm on the axle.... "Doing the Twist" (for those old enough to remember!) takes on an entirely new significance!

 

[stickshifter]

Plus with an automatic transmission the effective ratio may be lower if the torque converter allows for some slippage. Power transfer wont be as consistent or linear as with a manual trans tho.

I really hope you are right. I think the 54:1 crawl ratio will serve many people well, but for me, a low crawl ratio is one of the most important attributes in an off-road vehicle. I've had vehicles with very low crawl ratios, and vehicles with pretty high crawl ratios. For the type of driving I do, I have a strong preference for the low crawl ratios. Using the brakes during a steep descent (especially in the rocks), really sucks, and can be dangerous.

Having said all that, there are other specs in a vehicle that impact one's speed when descending a steep hill using just engine-braking; these include - but are not limited to - vehicle weight, engine torque, number of cylinders, and overall engine displacement. You'll get much better engine braking with 100:1 crawl ratio and a 6-liter V8 than you will with 150:1 crawl ratio and a 2-liter I4. We tend to use crawl ratio as the main measure of down-hill control, but there are other important factors to achieving a controlled descent.

I know very little about auto-transmissions. I learned to drive on the beach when I was 13 in a 3-speed manual (1968 International Scout); sand will teach you how to use a clutch I've been driving manuals ever since - so I am a little out of my depth here - but it is my understanding that a torque converter can allow slippage at low speed, and that this can serve as - roughly - an additional 2:1 reduction (some say it is more like 1.8:1 - but in either case it is quite significant). But apparently, this effect doesn't last very long.

According to Motortrend: "This sounds really great, and it is. But the catch is that this torque multiplication doesn't last very long. The multiplication factor is based on the speed difference between the turbine and impeller. At stall speed, the impeller is spinning at engine rpm and the turbine is stopped. This creates the greatest speed difference between the turbine and the impeller and therefore the maximum torque multiplication. Once the brakes (or the transbrake) is released and the vehicle begins to move, the turbine spins up and the speed difference between the two diminishes."

So now I don't really know what to think about how much a torque converter can actually lower the crawl ratio

Let's say there is an additional 2:1 reduction; does that mean the effective crawl ratio of the Grenadier is around 100:1? And if so, why are the wheels locked-up during the hill-descent between 1:20 - 1:27 in the video below? This is a genuine question - I'm not trolling here. Steep descents are really common where I live, and controlled descent is super important to me.

Just for fun, here is a 1968 International Scout:

 

[emax]

Looks quite a bit like one of the modern EVs ... ;-)

 

[painter]

We tend to use crawl ratio as the main measure of down-hill control ...

Hey, stickshifter,

Well, that shows how little I know... I was was only thinking of, and referring to, ascending.

For decent, I don't think the multiplier effect would come into play, because you'd probably be off the accelerator as well as manually selecting, and holding, a single gear anyway.

My 'wheeling days are some time ago. But back in the day I'd be with you, manual Low 1. Probably still the ultimate in driver control.

Now there is Hill Decent Control and the like. I haven't had experience or know much about those systems but I played back the video you linked in slow mo and suspect HDC is a factor. Of course don't know whats happening on the right hand side. And I sure don't know how the 3 lockers alter the equation.

Agree tho, it's not overly inspiring, kinda like that other "gold standard" hill decent video clip (which looked like a runaway to me).

Great question, sorry I'm not much help.

 

[stickshifter]

Hey, stickshifter,

Well, that shows how little I know... I was was only thinking of, and referring to, ascending.

For decent, I don't think the multiplier effect would come into play, because you'd probably be off the accelerator as well as manually selecting, and holding, a single gear anyway.

My 'wheeling days are some time ago. But back in the day I'd be with you, manual Low 1. Probably still the ultimate in driver control.

Now there is Hill Decent Control and the like. I haven't had experience or know much about those systems but I played back the video you linked in slow mo and suspect HDC is a factor. Of course don't know whats happening on the right hand side. And I sure don't know how the 3 lockers alter the equation.

Agree tho, it's not overly inspiring, kinda like that other "gold standard" hill decent video clip (which looked like a runaway to me).

Great question, sorry I'm not much help.

Hey painter,

Thanks for your reply. Yeah, I was thinking that they might be using HDC in the video, and that the computer was applying the brakes resulting in the wheels locking up. But I don't know - I've never used HDC - so I really don't know how it works (I thought part of its goal was to never lock-up the wheels, but I really don't know). To me, the great value of the Grenadier is getting a new vehicle that is built with old-school tech (as much as possible, anyway). I'd really prefer it to have a really low, low-range and not have HDC at all! I had an old FJ-40 and I could put that thing in first gear (low-range) and get out and walk next to the truck with one hand on the steering wheel (at least in the summer when I took the roof and doors off).

I think the Grenadier is the closest thing available to what I want to buy. I might have to just accept that it is 95% of what I want and not 100%. The only other thing close is the Wrangler, and its got a different set of issues...

 

[painter]

I'll add, we have a diesel F350 with a small popup slide in camper. The gear ratios for that year were:

Manual trans: 5.79/3.30/2.10/1.31/1.00/0.72 = Crawl 58.7:1 (2.72 TC, 3.73 final ratio)
Auto trans: 3.11/2.20/1.54/1.09/1.00/0.71 (4th is cold operation only) = Crawl 31.5:1 (as above)

So, at least back then, the AT option had "higher" gears than MT. I don't think that was uncommon or that AT buyers gave up as much as those numbers might imply. So I'm going with: there is (was) something to the torque converter multiplier effect, especially on first and maybe second gear.

For personal experience, our previous truck was a gas F250 with MT, ran the same camper. For the off highway driving we were doing (as opposed to "off roading") the auto vs manual trans wasn't a downgrade. Though to be fair, the newer truck has so much more torque and weight for tire traction that climbing hills is not a problem. I do ride the brakes more downhill tho, even with it in L1.

And it should be noted this current truck is longer, taller and much heavier (thank you weight gain) so sketchy stuff is mostly avoided, unless it's just a short pitch . Plus, we're on a different type of trip now (thank you graceful aging) ...

I wouldn't be overly concerned with the auto. Since you posted what I've read is all good about the ZF8.

And it's all were gonna get with that foot rest in there !

 

[stickshifter]

Yes, the ZF 8-speed is probably the best auto on the market (relevant to this application). I've driven a handful of Jeep Wranglers and Gladiators with it, and a couple of Power Wagons. I've never enjoyed driving an auto before the ZF, but I think this one is really excellent.