Thread: APT Rocksliders - D3

Originally Posted by Tombie

To get even close to the strength of the steel ones an alloy one will be twice as thick and only save around 3kg per side.

They will cost a shed load more, and once damaged will be a write-off item.

For some alternative perspective - I've got the GoE alloy ones and they are poorly designed and constructed. They don't fit well and are not overly strong given their bulk and structure. The powder coating is not durable and everything forward facing is bare alloy now despite mudflaps and relatively little time spent on gravel/dirt. Plus they have significant protrusions and hang-up points underneath and have no capping as previously mentioned. They are not the alloy poster child in any way. However a properly designed alloy set would be half the weight of equivalent steel ones of similar strength (typically 45-50% weight saving is realised for this sort of product). Same strength, half the weight. The only things you are giving away are that the alloy is harder to repair properly if really badly belted out of shape (ie creased or torn) and alloy doesn't slide as easily on sharp rocks, tending to gouge and drag more. As you stated they do tend to cost a bit more (emphasis on "a bit") than steel ones but that's somewhere around +30%. For my usage I like to have step/sliders to protect the sills but I don't typically seek out rock-hopping so it's more insurance and confidence to explore plus the functionality of accessing the roof area. A set of sliders/steps is a dead-set bargain against even a small dent on the sill or door. Honestly they could be fully sacrificial and would still pay for themselves ten-times over if wrecked. For others the steel vs alloy equation may favour the other side (like you ) but I'll take any weight saving I can on my already porky beast with limited payload. My D1 has steel step/sliders, brush bars, etc but it gets exposed to more challenging usage than my RRS.

Now for some real numbers: APT quote their step/sliders (steel) at 34kg for the pair. My GoE alloy ones are 16.5kg (pair). Of course the D3/4 has a few inches more wheelbase so there's a couple of kg extra in that, but the weight save is definitely there and can be seen to be about half. BTW - the factory side steps I removed were a significant 22.5kg (pair) so I got more protection for less weight.


Others have mentioned the grip tape and I can vouch for it working a treat. I have it on the rear roof ladder rungs on my D1 and it made a huge difference wet or dry. Highly recommended and cheap.

Good post!

Agree, there is a weight saving to be had. I’d be more concerned on modulus of elasticity though.

All things being equal, and both steel and alloy sliders being built to the same overall strength:

The alloy ones will be twice as thick,
The alloy ones will begin to deform under lesser impacts and won’t come back.

The overall weight saving then becomes ~10kg.

The risk however is deformation that bends the sill inside the slider. This is the most critical area to protect - stand off bars are the more sacrificial component.

100% agree that if overall weight is getting critical it needs to be saved then anything and everything needs be considered.

One such way to regain this weight is to switch auxiliary battery to Lithium etc.



Oh and a tip, be wary of grip tape if wearing shorts! It can easily carve open skin!

Yep, the modulus of elasticity being a third of steel can be a bit of a challenge. Some of the 'better' alloy grades are getting up towards mid-range steel for yield but it is inherently a fairly ductile material (some of the high tensile alloys are freakishly elastic however). I looked at this from the perspective of doing it "properly" (ie. with tailored extrusions, etc) so you can get the strength and sectional characteristics required with minimal extra weight or structure (webbing, internal bracing, etc). If you essentially just fabricate an alloy facsimile the exact same way you'd make the steel one then you'd need to nearly treble the thickness of the sections to get similar strength and at that point you are close to weight parity at higher cost and lower impact resistance. Just doesn't make sense. Which I think is your point, Tombie, and I agree. I also 100% agree that the sill protection is absolutely the thing it needs to do. Any damage pass-through here is abject failure. That'd be the reason I have the APT compressor guard in 4mm steel as caving that in would be really bad, but all other undershielding is in alloy as it can deflect a fair way before compromising function.

Look at APTs steps (as one example) and there are multiple folds wrapping around the sill and using eleven or twelve (?) fixing points per side. Very robust design that is weight-efficient for its (very high) strength. And the profile is smooth with no snagging points. Uses folds instead of welds wherever possible which provides even more strength. Also there is a decent gap between door swing and top of step so minor deflections (ie. bending) won't make you have to channel the Dukes of Hazard. Great example of good, thoughtful design. Undoubtedly robust and fit for purpose.

Now look at the GoE alloy abomination. A couple of bits of flat 10mm alloy strap 90deg butt welded in a few small places and only using six fixings per side to the vehicle. I drilled through to every other factory point I could use (underneath) to increase that to nine and give it half a chance of spreading the load and doing its job if clouted. And then there are the reinforcements that hang down significantly in four places per side without ramps that are perfect snagging points if you do try and use them as sliders. I had to pack my steps down to clear the doors. Actually dragged along the door trims as made. Both steps get mostly wiped clear of dirt any time the doors are opened as the swing clearance is so small even after spacing down. And I've had a situation where I couldn't open a rear door because a small rock had flicked up through the gap and jammed between door and slider. The door lower seals don't engage the slider either (leaving a gap) so the door jambs get packed with crud. How is that a good design? Aaargh.

After writing all that I've nearly convinced myself to just get APT steel ones instead and go on a diet to offset the added bulk....

Pic attached of what I'm talking about. This is awhile ago after fitting the GoE steps and APT tank & compressor guards, but before fitting the rest of the APT undershielding.

20190124_203738.jpg

Thanks, the weight loss bit put a smile on my face!

I’ve just lost a little over 30kg in the last few months so can completely relate to the comment

Even noticed the Pwr to Weight ratio on my bike is improving significantly

Originally Posted by DiscoClax

After writing all that I've nearly convinced myself to just get APT steel ones instead and go on a diet to offset the added bulk...

Great summary. I went through much the same thinking back when I bought a very early set of the APT sliders. I think I may have had the first set with the bottom skid plate (for a D4). I had the advantage of close inspection of the competition on a friend's D4. Noted all the issues you mentioned plus an actual major tubing dent.

Regards,
Scott

PS .... the diet is still a work in progress

Originally Posted by Tombie

Thanks, the weight loss bit put a smile on my face!

I’ve just lost a little over 30kg in the last few months so can completely relate to the comment

Even noticed the Pwr to Weight ratio on my bike is improving significantly

Great work! I knocked off a bit over 20kg a year ago and have held that off and it has made a massive difference. I reckon I need to get closer to your number though so there's still work to do...