Trail carnage

[Matt H]

I think the factor that is perhaps making the difference here is the Moab slickrock? In regular dirt you can get away with a little tyre scuff. But the super high traction surface they have in the Moab area is like driving on sandpaper. Many trails have steep uphill sections and have tight corners at the top to navigate.
Any time your on the gas, a Detriot locker is locked. High traction + locked diff causes the axle to wind up. You need to be on the gas to make the climb but there is little or no tyre slip allowed by the rock surface as you negotiate the tight turn. When I was down there a couple of years ago I found I had to disengage my ARB lockers as soon as I could to prevent this from happening.

And of course Trevor does like to let her buck a little  ;D.

I think he runs aftermarket 4.11:1 gearing.

[Trevor]

If you switch to a selectable locker your shafts won't be taking a beating 24/7.

I personally don't think that is the case.  There is very little force needed to unlock a Detroit when it is in good shape.  On the road, there is no binding up of the axles.  Where Trevor is stressing it, he needs the diff locked.  I've run one for the last ten years and you would not know it is there. The biggest downside is the "small" Detroits used in a Rover diff get damaged when a shaft breaks.

Trevor is breaking ground.  I would be surprised if anyone else has broken an RCV 4340 shaft on 32s.  I've only heard of it happening with race guys on big tires.  How old are the shafts?  Ashcroft does have a 5 year warranty against breakage.  I'm sure they would credit the cost to upgrade to 300M.

Is the R&P stock?  The ones available now are a lot better designed than what you could get a few years back.

The R&P are GBR 4.11's. I've had those in for a couple years now. The axles I bought right around 5 years ago. I will dig up the invoice when I get home to check as I had completely forgotten about their warranty. Some replacement 300M's would be nice. :)

New R&P's are on my short list. I'd like to get something in the 4.50 or 4.75 range, pegged and with a heavy duty design. The 4.11's I have are good and have held up ok, but they are just not going to last, especially if I start moving to 300M shafts. Those axles did see a lot of Moab too, about 8-9 trips. They've seen some tough miles.

I've bounced back on forth about moving to air lockers. I do really like the Detroit/Trutrac combo I have. A full lock up front would be nice, and it may be the first candidate to get an Ashcroft air locker and continue to run the Detroit in the back, since it brand new.

As an aside I ran with  my TC off today. I just tripped the 3 amigo's and let things stay that way. We ran Steel bender which has it fair share of tough climes. It's too early to tell, but the lack of TC felt better. It will take some more testing but things just felt smoother...well, as smooth as things cna feel bouncing up a rock wall  ;).

[Red90]

For what it is worth, a Detroit can allow the outside tire to overrun the ring gear under power in a corner.  Sometimes they do get stuck, but it should release normally.  What is your experience, Trevor, on the slickrock?  Do you find it binding in tight turns under power?

Did you talk to Bill of GBR about things?  I'm sure he must have an opinion.  ;)

[Trevor]

I've found that it behaves as expected most of the time. It's not fool proof though as it will stay locked longer than it should at times. I find that mostly occurs after you've done a climb of some sort and the trail curves out but still at an incline, so you don't really unload completely. In those instances the detroit will often stay locked up as you turn.

That said, I do find you also get a good feel for the slickrock effect fairly fast too and its not too hard to manage.

[binch]

A friend of mine broke his Ashcroft shafts winch trialing and they wouldn't honour their warranty so he's going to Australia for some fancy ones that are stupid expensive. ;D

[Matt H]

For what it is worth, a Detroit can allow the outside tire to overrun the ring gear under power in a corner.

I always thought that only happened under partial-low throttle? I had a Detroit in the 14 bolt rear axle of my 87 Chevy pickup many years ago and that damed thing was savage. I pretty much had to coast around corners. I'm the first to admit I was a bit of a lead foot driver back then so my experience is probably not that accurate.

Looks like Trevor is heading towards a full fabricated/custom axle. You can only do so much with the Rover stuff before you run into the law of diminishing returns. 
Unless things have changed recently I've never heard anything encouraging about Rover axles and gearing deeper than 4.11:1. I've never tried it myself but it seems that there just isn't enough gear tooth strength if you go lower (higher numerically) than that?

[Red90]

I suspect the modern Detroits are better at unlocking under load. The other thing to understand is that in a corner only the inside tire gets power. The outside tire goes free. On a 2wd vehicle this does strange things as you a trying to turn with an inside tire only pushing you.  They are not really a good choice for street use because of this.  It gives poor cornering behaviour and traction.  With 4WD. the front axle pulls you around and it is not as noticeable.

On the ring gear question there have been a lot of changes in the last few years. The available gears are much better designed with less flexible rings and laer, stronger teeth. Pinning is the big thing though. The case and gear is too flexible and under load moves away from the pinion. When you get the load at the tip, the stress is over double on the tooth.  From the best I can tell, the new gears when pinned make the R&P stronger than can be achieved by the axle shafts.

[Red90]

A friend of mine broke his Ashcroft shafts winch trialing and they wouldn't honour their warranty so he's going to Australia for some fancy ones that are stupid expensive. ;D

There must be a lot more to that story.  Only the current generation ones have a failure warranty.  They have the best customer service of any company I've seen.  There is no point spending more money elsewhere. There is no way to make them stronger at that size. RCV knows what they are doing.  That and the only shafts in Australia that are comparable are the Maxi-Drive ones. They are not stronger.  The material science behind what is used for axle shafts was all known and put into text books before any of us were born.  The company that makes the shafts for Ashcroft are as knowledgable as anyone out there (http://www.rcvperformance.com/about.aspx).  You can find as good a shaft elsewhere, but it won't be better, so there is no point in spending more.

[Trevor]

A bit of an update on this thread. I decided to go with the the Ashcroft 300M option...a complete set of front and rear shafts, with HD CV's, arrived the other day. I'll be installing them before heading down to Moab in September.

Figured there's no sense messing around, go big or go home :).

Also got a couple diff pegging kits from Ashcroft as well. On my way back from Moab I'm going to pickup a set of 4.71 Extreme Duty ring and pinions from GBR, and then peg the diffs when I swap them over. One more winter project!

And to think, if I had not got into offroading all those years ago I could have bought something practical with all the money I saved....like my own island, or Conneticut.

[binch]

ROFL ;D

[Matt H]

Well I like to justify it like this.

To get to the same places as I can in my 4WD by other means I would need to spend even more money.
I could buy a helicopter and fly. Probably die in a crash in poor weather.
Buy a horse, ranch to keep the horse, horse trailer and truck to pull it within 20km of area (requiring a 4WD so this option doesn't count) likely die of hypothermia or heat stroke.
Buy a motorcycle and die in traffic before I ever get off the #2 Hwy. If by some miracle I make it off the black top to a dirt road I would still likely die of hypothermia or heat stroke. Or go deaf from the aweful exhaust noise they make. Not hear a Bear and get mauled to death.
Buy a Quad or Side by side, trailer and truck to pull it to within 20km of area (requiring a 4WD so this entire option also doesn't count) die of hypothermia or heat stroke. Or go deaf from the aweful exhaust noise they make. Not hear a Bear and get mauled to death.....again.

All the above options are vastly more expensive than a 4WD and are potentially deadly!

Of course I could walk or mountain bike and while those are significantly cheaper, I would never actually get to where I want to go in one lifetime so they don't count either. Plus there is the "Bear" issue. I'm not young or fit enough to out run/peddle a Bear.

So all things considered I think you should give yourself a pat on the back for choosing the more thrifty (not to mention safer) option. 

[Trevor]

Lol, I like the way you think Matt! Bravo!

[binch]

If I didn't know any better I'd say I'd seen Matt in a four Yorkshire men skit of monty pythons!!!

Great Rant there Matt....really enjoyed that  ;D