ChrisW

Notwithstanding Carnity’s very welcome approach of stock cars being entirely suitable in the early stages - I wanted to start a discussion on the merits of having a winch and aftermarket bumper. I’ve been conscious of power vs weight with my Jeep (the 3.8L engine is not blessed with much other than a thirst for oil), and having gone back to check the data sheets - I’ve discovered that my winch weighs 60lb and my steel bumper comes in at a whopping 140lb. That’s basically an adult sat ahead of the front axles…not great for balance or overall mass. On the upside however I have a bumper that is pretty rugged, unlikely to get damaged any time soon, has some solid tow points, and a winch that could scale the side of a mountain single-handedly. So…I’m curious to hear views on at what stage a winch is genuinely useful to have, the merits of stock vs near stock vs fully rugged bumpers, - and given the choice between lightness or resilience, which way our resident desert rats would run…

😂😂 Oh man - we should have stayed on the sand!

Yeah, I live in AD so the speed limit and red light traffic cameras are a well known feature for me! I have to admit that I thought I’d already crossed in to Dubai side and had a little slack as compared to the signs.

Not sure if you caught my earlier post - but I had the same issue, and my solution was to change the ring and pinion (final drive ratio) - aka regearing.

I’m not sure that’s the case: - The Rubicon transfer case is 4:1…you’ll be spinning the engine and transmission really fast when running at average speeds - The Rub’s transfer case is also meant for rock crawling…running it continuously at higher RPMs and power will likely cause it to prematurely fail. That’s not to say that when conditions call for it (certain climbs, recoveries etc), then it makes sense - but full time general sand driving will probably trash the transfer case or other parts prematurely.

That was really good fun - some nice technical practice, a few good ridges, and some (mis)adventures to learn from. Thank you @DP1011 for leading, and @Alexanderrr for giving me some good tracks to follow! Great support from @Luke K P and @Hani crest king too - thank you. I was very impressed with the on-the-drive coaching you all gave. I think the main takeaways for me were a reminder in the fundamentals of momentum driving on technical dunes (especially given the soft sand), and consistently applying the basics on ridge crossings (particularly being stable on the ridge before manoeuvring onward). It was also such a good drive that the AD police sent me a nice picture to remember it by… 🤦🏻‍♂️🤦🏻‍♂️🤦🏻‍♂️

For those sufficiently curious - these were the quick total drive ratio sums…

I have some views @Josh S, but I should caveat the following by saying that I’m not an experienced sand off-roader or Jeep driver! I do however have a technical background and have driven various car setups and terrains over the years. I have a Jeep JK with a six speed manual and 3.8L engine, which is fairly notorious for being uninspiring at the best of times. The powerband really comes in above 3000 RPM - much less and you can easily start to have decaying RPM on an uphill section or soft sand, and sadly 5000 RPM is pretty much where you top out for power and torque; so the useful power window is narrow. After my first few drives on sand (pre-Carnity) with this car, I was worried that I’d made a bad decision. On technical dunes it was incredibly difficult to drive slow enough in 4H to keep behind folk driving technical dunes, and on faster sections it was a continual swap between first and second car - often with shifts being required mid-manoeuvre! Hard work, not much fun. I then did the bad thing - I did a drive in 4L. Wow…it was much easier; suddenly now third gear was my default starting gear and I had a lot more control available to me by coming up and down from there. Staying in the useful power band was easy. But…the transfer case really doesn’t want to be driving at high speed…you will kill the planetary gears eventually. What that did was to set me off wondering why that is - and this is what I found. - The default Jeep Wrangler Sport has a final drive ratio of 3.21 - so in order you have engine, transfer case, gearbox, final drive (ring and pinion), wheels. What this means is that the car is biased to have less RPM at high speed, whereas on sand (and given the gutless engine), we want more of the RPM at lower speed. Selecting 4L does that. - The first gear on this particular JK is very long; it covers a really wide speed range. Coupled with a low final drive ratio, it makes it hard work…you can’t really crawl, and you end up sticking with first gear until quite high speed. What can be done about this? Good news is that you have options. You can change the final drive ratio to a variety of different options. This is quite common in the US where the rock-crawling crowd like to run really big tyres, and you need to shift the RPMs around. I did some maths using the transmission data sheets, and what I found is that the golden 2/3/4th gears in 4L could be approximately replicated as 1/2/3 in 4H if I swapped the rack and pinion from 3.21 to 4.56. You can also go to 4.88 and 5.21 if you want your 4H first gear to be a crawling gear - the caution just being that you’ll be cruising on the highway at high RPMs (…as is often the case with engineering issues, you can only optimise for one thing at a time!). Circa five thousand dirham later I now have a Jeep I enjoy driving on sand, and the lingering thought that I perhaps bought the wrong car in the first place…but we learn. This car isn’t my daily driver, so optimising it for the low end worked for me - and I just enjoy drifting along at 100-120kph on the main road.

Thank you kindly, @Looper @Frederic - you’ve all created a great culture in this group.

Thank you, @DP1011! Looking forward to joining you on Saturday.

Thanks again, @Davie Chase - that was my first fewbie drive and I really enjoyed it. Great support from @Batuhan Kulac @Mark B @Gary F @Benjamin - thank you! I also had the pleasure of following @Talal H …I hope you don’t mind me sharing what started our fun with shovels…

That was an excellent drive and I was able to learn and put together experience from past drives. Thank you for leading @JeromeFJ, and great support from @Benjamin @Joji varghese and @Gary F - thank you.

Thank you kindly, @Gaurav - and to all the other drive leads and mentors who have kindly helped my initial learning. Really excited to stretch a little further now.

Thanks for taking the time to write that up - exactly as you briefed on the sand, and as you say, the technique works provided you make a prompt decision. Hoping next time to practice getting the crossing a bit more consistent. Also, not wanting the learning point and Davie’s explanation go to waste, I’ve uploaded a “dewarped” version that tells a slightly better story:

Morning all - thank you for a really enjoyable drive. @Gaurav great leadership as always, and @Davie Chase thank you for helping me out down at the tail end! I had a good learning moment yesterday about the risks of sticking with a ridge crossing rather than rejecting and turning down with gravity - I thought I'd share the following still images and invite @Davie Chase to perhaps share a few of the mentoring words he gave me during the break about what went wrong, and what to do differently next time... The first six images are start-middle-end looking at the car, and the latter four images are the same timeframe but with a "drivers eye" perspective of approach, mid-move, exit.