Low Range Gear Ratio

[stickshifter]

Hi folks,
In this video from November 2021, they seem to be discussing the low-range gear ratio. This is the first specific info I've seen on the topic. I believe that the driver (who works for Ineos) says that the low range ratio is 2.5 to 1 (2.5:1). He is German, and he is speaking in English, so I'm not completely sure I am hearing this right. If you are interested, go to 7:40 (7 minutes 40 seconds) in the video and listen for yourself. For comparison, a Jeep Wrangler Sport is approximately 2.7:1 and the Wrangler Rubicon is 4.0:1 (super low). For most rock-crawling, and on any steep climb or descent, the lower the better. For a lot of other off-roading (deep sand, desert running) 4.0:1 is too low. For my personal use, I like a really low, low-range. A low-range ratio of 2.5:1 would not be my choice...  It would be great if some of you watched the 10-seconds in which they discuss the gear ratio, and let me know if you think I heard correctly, or if I misunderstood. Hope you all have a Happy and safe New Year's Eve!
https://www.youtube.com/watch?v=c0usAUV39Yk

 

[d1rty]

I heard it the same way, FWIW.  I agree that 4:1 is for rock crawlers.  Quick google search shows most trucks at 2.7ish range - the outliers being the mid-size Toyotas (Tacoma, 4Runner) at 2.57:1.  For the Gwagen I found a spec stating 0.87:1 in high and 2.16:1 in low.  I thank that works out to roughly 2.5:1 difference between low and high - which is not at all surprising based on who did the engineering on the Gwagen and the Grenadier.

So it's in the ballpark of most other vehicles in the class.  Would an extra 10% gearing for low range be nice?  Maybe.  Are closer ratio gears (all other variables held equal) stronger?  Yes.  It's all about the compromises you want to make.

 

[stickshifter]

I heard it the same way, FWIW.  I agree that 4:1 is for rock crawlers.  Quick google search shows most trucks at 2.7ish range - the outliers being the mid-size Toyotas (Tacoma, 4Runner) at 2.57:1.  For the Gwagen I found a spec stating 0.87:1 in high and 2.16:1 in low.  I thank that works out to roughly 2.5:1 difference between low and high - which is not at all surprising based on who did the engineering on the Gwagen and the Grenadier.

So it's in the ballpark of most other vehicles in the class.  Would an extra 10% gearing for low range be nice?  Maybe.  Are closer ratio gears (all other variables held equal) stronger?  Yes.  It's all about the compromises you want to make.

Thanks for your reply!

 

[ChasingOurTrunks]

The gear ratio seems competitive with others in the segment. I wonder if he's talking about the "At the wheel" ratio or if he's just referring to the transfer case's hard gear ratio. This is not my forte, but the T-case being 2.5 to 1 doesn't mean that it has a crawl ratio of 2.5 to 1, as it depends on how low the bottom gear of the auto trans is, doesn't it?

 

[stickshifter]

The gear ratio seems competitive with others in the segment. I wonder if he's talking about the "At the wheel" ratio or if he's just referring to the transfer case's hard gear ratio. This is not my forte, but the T-case being 2.5 to 1 doesn't mean that it has a crawl ratio of 2.5 to 1, as it depends on how low the bottom gear of the auto trans is, doesn't it?

You are absolutely right: the crawl ratio is what is important.

The crawl ratio is the number of rotations your engine makes before your tires make one full turn. The ratio is calculated by multiplying your transmission, transfer case, and ring and pinion gear ratios.

Grenadier transmission gearing for first gear: unknown at this point (as far as I know)
Grenadier transfer case low-range gearing: 2.5:1
Grenadier ring & pinion (i.e. axle ratio): unknown at this point (as far as I know)

The actual speed of the vehicle when in low range, in first gear, will also be affected by the tire size. The taller the tire (when holding all other variable constant) the faster the vehicle-speed.

With an 8-speed transmission, first gear could be quite low. We also don't know the ring & pinion, or axle ratio. So we could still have a low crawl ratio even with a not super-low (2.5:1), low range gear ratio.

All the best!

 

[DenisM]

Thank you for posting this spec. on the transfer case. Just for clarification...I noted from comments elsewhere, they (Ineos) have specifically stated that while the Grenadier has been designed for "hard work", they have not designed it for "hard core"   off-road as such ...i.e. rock crawling. The TF case is their own in-house design mated to an upgraded "modular" ZF 8 speed.  I can't wait!!?

 

[Gr84dier]

Thank you for posting this spec. on the transfer case. Just for clarification...I noted from comments elsewhere, they (Ineos) have specifically stated that while the Grenadier has been designed for "hard work", they have not designed it for "hard core" off-road as such ...i.e. rock crawling. The TF case is their own in-house design mated to an upgraded "modular" ZF 8 speed. I can't wait!!?

Hi DenisM:
Their TF Case is from Tremec

 

[DCPU]

 

[emax]

From when is this article?

 

[stickshifter]

Just FYI: this thread was started back in January. Since then, we have learned much more about gear ratios.

Grenadier transmission gearing for first gear in the B58 (petrol/gas) version: 5.25
Grenadier transfer case low-range gearing: 2.5
Grenadier ring & pinion (i.e. axle ratio): 4.1

This gives the Grenadier a crawl ratio of 53.8:1 (5.25 times 2.5 times 4.1). For simplicity, I think we can call the crawl ratio 54:1

 

[bemax]

Page 25 of the Supplier Bulletin
August 2021

 

[Scan4]

 

[Scan4]

Do you know who is responsible for the AC?

 

[DenisM]

Wondering if anybody has data on the ratios of the 8sp ZF box used on the B57 (8HP76) ?

 

[DaveB]

Wondering if anybody has data on the ratios of the 8sp ZF box used on the B57 (8HP76) ?

 

[DenisM]

yep.. thanks Dave.....I should have been more specific.
I saw all that "data" in the brochure but am looking for the actual numbers..... maybe it will be in the owner's manual.

 

[stickshifter]

Hi Denis,

I found this info from a google search on both the 8HP51 (for the B58) and the 8HP76 (for the B57). The title for each table is hot-linked to the source. I can't speak to the accuracy of the sources. NOTE: the data for first gear in the 8HP76 in this table does not correspond to the data presented by Ineos in the table Dave posted, so maybe my source is incorrect, or maybe the transmission has been tweaked for application in the Grenadier. That's my best effort before a cup of coffee

8HP51 (Gen 3) Gear Ratios:​

• 1st gear 5.25
• 2nd gear 3.36
• 3rd gear 2.17
• 4th gear 1.72
• 5th gear 1.32
• 6th gear 1.00
• 7th gear 0.82
• 8th gear 0.64
• Reverse 3.71
• Fluid Capacity: Roughly 6 liters
• Fluid Type: ZF LifeguardFluid 8 or equivalent
• Torque Limit: 500 NM (369 lb-ft)

8HP76 Transmission in the Alpina B7​

Type	8-Speed Sport-Automatic ZF 8HP76 SWITCH-TRONIC
1st	5,00
2nd	3,20
3rd	2,14
4th	1,72
5th	1,31
6th	1,00
7th	0,82
8th	0,64
Final drive ratio	2,81

 

[DaveB]

yep.. thanks Dave.....I should have been more specific.
I saw all that "data" in the brochure but am looking for the actual numbers..... maybe it will be in the owner's manual.

A genuine question so not meaning to be difficult but why do you need that information?
What are you planning to use it for?
I may have the same need and not know it.

 

[Krabby]

Page 25 of the Supplier Bulletin
August 2021

Where was this found? Is there an up-to-date one? This list is August 2021 and I’d imagine some suppliers have changed. It’s fascinating to see where components are coming from.

 

[bemax]

Where was this found? Is there an up-to-date one? This list is August 2021 and I’d imagine some suppliers have changed. It’s fascinating to see where components are coming from.

I never found an actualised one.
It might be a task for DCPU.
If he doesn’t find it it doesn’t exist or he has his own dark reasons for not sharing it with us!