I wonder how the Ford 8" compares to the Toyota 8" stuff? It could be another good option for a portal center section if the 9" is deemed too big/heavy. They have a third pinion bearing and have decent aftermarket support, although not nearly as good as the 9". There was even a company that used to make aluminum thirds for them too. Most of the classic Ford guys say they are good for 300-350 HP, so it seems like they would hold up decently.
The beauty of portals is that you don't need 35-40 spline shafts, so a competition ARB shouldn't really be necessary. I think pretty much all of the JHF HMMWV portal buggies are running 30 spline axles. The smaller diameter axle shafts also help with shock loading since they can twist more than a larger diameter shaft.
I've got a couple 8" Fords out in the axle pile to play around with IF I ever make the time to do it. The differential share the same R.G. bolt pattern as the 9" Ford, but it is 3/4" shorter than the 9". Currie used to take the OE Ford 9" LSDs and re-machine the pinion side 3/4" shorter and viola you have a 31 spline LSD for the 8" 3rd.
Have always wondered if you could do the same with a couple old school RD55 Air Lockers. I do have one or two in a corner somewhere....hmmm.
It’s CE, and maybe I’m making that up because I know where they came from. But the RD99CE revision came from Shannon Campbell and Bill Baird.
Supposedly CE stands for Competition Edition, but the joke around the ARB offices back in the day was it stood for Campbell Edition, because they were created to withstand the abuse from Shannon's racing.
This has been disproven many times.
A 40sp shaft will take the shock loads a lot better than a 30sp, I don't care how you slice it.
Yes, a 40 spline can take more shock than a 30 spline shaft, but it will also pass more of a shock load further upstream into other components. The twist in a shaft helps absorb the shock to keep form passing it into the ring and pinion or further up the drivetrain.
40 spline vs 30 spline is not a great comparison due to diameter difference. Maybe a 1.5" 35 spline vs the 1.75" 40 spline would be the better comparison. If you were to build that 1.5" 35 spline shaft and a 1.75" 40 spline shaft out of the same material, the 1.75" 35 spline shaft would have approx. 83% less twist. Absorbing less shock load and passing it upstream through other components.
One good example of passing the shock load through the shafts upstream is when I got a chance to chat with Dennis Anderson (Grave Digger fame). When they first built his 1800hp King Sling mud truck, they were originally using some (iirc) Ouverson 2" shafts in the front F106 axle. The first few hard runs out, they were breaking ring and pinions in the F106. Ouverson then built them some 1.75" 40 spline shafts and they stopped breaking ring and pinions. The smaller diameter 1.75" 40 spline shafts were twisting just enough to absorb some of the shock load, saving the R&Ps. The stiffer 2" shafts were passing enough shock load into the 3rd to break the R&P.
Sandy Cone (desert axle builder extraordinaire) and I talked about the 36 spline shafts for KOH applications and he didn't like them, says it passed too much shock into other components, but the whole bigger is better mentality is always king. He had told me, along with a couple others in the industry that the big name race teams were swapping out R&Ps after every race due to possible shock-loading issues with the gears.
In reality, the 9"/10" is undersized for what people in competition ask of it. Someone really needs to develop a true 10" or 10.5" version of the 9". The so-called 10" gear sets in racing use today are better, but not a true upgrade as they are still running an undersized differential.
ARB RD249CE 40 Spline Air Locker
gearworksinc.com
maybe
Tech Tim can give all the details, but i was under the impression that the improvements need to make the collar have better engagement (which is what was failing) was not possible because there physically was not room to resolve the issue. there was some collars made from super fancy materials that increased the durability but ultimately were a very expensive bandaid.
Both Spidertrax and Wild West were offering 300m locking rings for the RD99. Yes, the 300m clutch gears were a lot stronger, sometimes stronger than other components in the Air Locker. But there was also a lot more things in play causing the failures. One of the single most important items was to get enough air pressure into the Air Locker to hold them lock under severe racing loads. We first bumped them up to 150psi (max pressure with the electric solenoids) and then later were bumping them up to 200psi and even 300psi with air switches.
Pinched air lines were also a cause of a lot of issue in those early days. That soft copper alloy line ARB used was awesome to work with, easy to bend and route. But it was also easy to over tightened the fittings and compress the airline down small enough that it was causing delayed lock ins, which in turn would caused chipped locking gears when load was applied and the locker wasn't locked in all the way.
Wild West also went on to offer 300m locking rings for the RD114 14 bolt air locker. Never had a single issue with those swapped in and running enough air pressure, everything in those Air Lockers were burly.
I didn't help with the development of the RD99CE/249CE, so I can't speak of all the improvements. The little I do know about them, ARB went to forged gears (I believe now that all Air Lockers have forged gears) and they changed the center block to better support the side and spider gears along with a stronger outer case.
IMO, one of the best Improvements that never happened was the new end cap that Ashcroft in the UK built. Instead of splitting the locking gear engagement with the side gear and the case, they moved the case engagement out to the outside of the clutch gear, directly into the end cap, allowing more engagement at the side gear. There was a thread with pics on the old board, I don't have pics of that set-up anymore.
I’d say the problem is fixed. But you can’t erase the negative memories of a first version from the people who suffered the failures.
The stigma is still showing its head, even in this thread a little.