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Rock-Sliders
11-14-2012, 06:42 PM
Post: #1
Rock-Sliders
I've given my Syncro a slight dent because I've wanted to build these a long time ago but never got to it...

Well... here it is.
Its strong and well fitted, it will give your long range fuel tank protection, under and side body protection and also serves as a small "step"...

Its mild steel 50x50x4.5mm and uses 32mmx3mm pipe to fit to the original jack-points..
I did not want to drill holes into the chassis and thats why it mounts to the original jack-points that is made of 3mm think metal..

Who would be interested in a set?

I might be able to cut on the price if there is enough that is interested but for now ... depending on the steel price...
R2500 a set, Powder-coated.

You will however have to drill four holes and weld four nuts to the jack points.


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11-14-2012, 11:03 PM
Post: #2
Re: Rock-Sliders
As before- count me in

I'll show you a place
High on a desert plain
Where the streets have no name
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11-16-2012, 12:39 PM
Post: #3
Re: Rock-Sliders
Hi all,

As I am an Engineer and more into "method behind things", I was wondering if the rock sliders (design and material selection) would be suficient to do the job they are, purchased and fitted, for. I remembered reading a thread on the "4x4 forum" on this subject. I will try and copy some of the content on here, but feel free to search for the complete thread. looks like it was posted on (03.12.09) search for "Rosck slider".

"The general method to do this is to use a thick(ish) walled pipe. Although this is practical and strong, IMO sqaure/rectangular tubing is a better option. The bending resistance of a member (be it pipe or SQ tube is determined by the second moment of area of the member. A list of formulas used to determine this is available here. A list with section properties is attached - look at the Ixx value.

Using this to compare a pipe with sq tubing, let assume 60 x 3 pipe compared with 50x3 SQ tubing. The sections are selected with simular weight per meter, and thus cost, in mind.

Pipe: I= 129 000mm^4

SQ Tubing: I = 190 000mm^4 (47% stiffer than pipe)

The difference is marginal, but now concider a 76 x 50 x 3 rect tubing.

Rect tube: I = 528 000mm^4. (309% stiffer than the pipe).

Now compare the masses:

Pipe: 4.24 kg/m
SQ Tube: 4.18 kg/m
Rect tube: 4.84 kg/m

From this data the rect tubing is clearly the best section to use by far, but might reduce the break over angle of the vehicle. IMHO you want the rock slider to sit equal height or HIGHER than the chassis, but not lower. Should a 76 mm section fit in this criteria, I would attempt to use that, alternatively, the 50mm sq tube is smaller, lighter and stronger option than a 60mm pipe.

This comparison is only done to explain why I feel that SQ tubing is better to use than pipe.

Now question that arise is, how strong do I need to make the slider bar? I designed mine to be able to handle the GVM x 3! You obviously have to divide this by 2 to get the force applied to one slider bar. The Fortuner has a GVM of 2510 kg. The slider bar should thus be able to handle (2510 x 3)/2 kg = 3 765kg. I decided to go for 4 000 kg or 39 240 N (multiply kg with 9.81 to get N - or to make it simpler, multiply by 10). So well design for 40 000N.

Here I stood on a round rock, which spun out from under the wheel, the car fell about 300mm before landing hard on the slider - no damage to the car or slider bar.

The design criteria for me was deflection. I did not want more than 10mm deflection, because the sliders is located 15mm from the body - it looks better than having them 30mm away ... The weakest point of the slider bar (where most deflection occurs) is half way between the two mountings. The calculation for a simply supported beam applies here.



We know that:

F= 40 000N
L= 1.3m (measure on the vehicle how far apart the centers of the mounting brackets will be)
E = 200e9 (constant for steel)
I = To be calculated
y = 0.01m (10mm) (deflection)

The formula for the deflection:

y = FL^3/48EI

Thus

I = FL^3/48Ey
= 1.19e-6 m^4
= 1 190 041 mm^4 (multiply 4 by 1000x1000x1000x1000 to go from m^4 to mm^4)

From this it is clear that the 76x50x3 section would not be able to handle the force within the specified deflection limit. You would require a 100x50x3.5 section to handle the force. This is obviously way to large, and not practical, so now you have three options, design a custom section to handle the force, add a third mounting point to the vehicle, or reduce the requirement of 10mm deflection to a larger value.

I designed a section which I fabricated form a laser cut and bend plate with gussets and cross stiffners to handle the force - something which you'll most probably require specialized software for. Here is a picture of what I did. I traced the profile of the vehicle under the doors, and designed the slider bar according to that."

Perhaps a bit of useless information for some, but I hope it makes sense.

Regards,
Herman
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11-16-2012, 06:50 PM
Post: #4
Re: Rock-Sliders
Eish
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11-17-2012, 07:39 AM
Post: #5
Re: Rock-Sliders
These are commonly known as rock sliders but arnt relay as they will not hold the weight of a van.
They are more rock or tree deflectors as from a side impact.
I have been making and using sliders for many years on my syncros and they have saved my sliding doors on many occasions.
If you fit an infill pane between the slider and the body it will also prevent all that gritty stuff on your sliding door seal and bottom runner.
You also dont want the front to be blunt as this will catch on things and sometimes draw obstacles into your body work.
BUT the most effective place they are for is parking lots. No more dents from other unconcerned car owner's doors.
Russel


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01-21-2013, 03:08 PM
Post: #6
Re: Rock-Sliders
EcLiPsE, what do these rails weigh per side?
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01-21-2013, 05:36 PM
Post: #7
Re: Rock-Sliders
No idea, ill try and check at some stage

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01-23-2013, 09:03 AM
Post: #8
Re: Rock-Sliders
I suspect it's at least 10 to 12 kg a side
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04-22-2014, 12:55 PM
Post: #9
Rock-Sliders
10kg per side yes!

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