# Calculating shear strength of bolts on corrugated roads



## malmac (Dec 26, 2018)

Hi Team, We are installing a 2nd diesel tank for a vehicle which is going to see long distance travel on corrugated roads.

Shear strength for the bolts (10mm 8.8 bolts are the plan) is readily available. However the impact of corrugations must certainly increase the likelihood of failure from metal fatigue or coming loose. I would assume the coming loose is a question of torquing the bolt adequately - however the shear strength is an unknown to me.

Do any of you have any insights into this question.
	

		
			
		

		
	




Here is a rough diagram of how I would install the bosses for the bolts. 

Thanks in advance.

Mal


----------



## john.k (Dec 26, 2018)

With a tank in a SUV ,you wont have a problem......In a truck,there is a lot more impact load,but the tank will crack,the bolts will be OK........you should note you also have to comply with relevant ADRs.....


----------



## pontiac428 (Dec 26, 2018)

john.k is right, cracking is going to be the greater concern.  OEM tanks are soft mounted, usually with a pair of straps.  This allows the normal twisting behavior between frame rails to occur.  In order to combat fatigue cracking, use as few mounts as possible, and make them soft.  For example, I soft mounted a 100 gal transfer tank to a truck body using four 3/8" anchor bolts with valve springs as washers.  It held up to off road work for years.


----------



## GrayTech (Dec 26, 2018)

I second soft mount with straps. The stresses surrounding you hard mounts will crack the tank in short order. 

Sent from my H3123 using Tapatalk


----------



## P. Waller (Dec 26, 2018)

What is a corrugated road?


----------



## T Bredehoft (Dec 26, 2018)

Originally it was a road paved paved with logs, laid crosswise.  Stone roads when left unmaintained will develop a surface similar to  ripples or corduroy fabric.


----------



## vocatexas (Dec 26, 2018)

Down where I'm at we call them 'washboard' roads after the old washboards that were used to do laundry by hand.


----------



## Downwindtracker2 (Dec 27, 2018)

They go on for kilometers. It's not like here. We went up to Mitchell Falls, all day. 8" deep. You know the advice, air down  and speed up . From my experience of pounding gravel roads,  use high quality six ply or better tires. Ripped shale and granite blastings are called gravel here.


----------



## Downunder Bob (Dec 27, 2018)

Corrugated roads are the norm here in Australia. Mal the original poster is in Australia, and would be very familiar with them they destroy vehicles very quickly. They are named after corrugated iron which is a sheet building material usually rolled steel that is galvanized for weather resistance. The sheet is rolled with these corrugations much like a sine wave. On many country roads these corrugations can get quite large, and are very destructive to vehicles using them.


----------



## malmac (Dec 27, 2018)

Thank you for the input. I was planning to have the tank with a rubber mounting system - but given the helpful comments, I am going back to the drawing board and thinking it through again. 

Thanks for everyone's thoughts.

Mal


----------



## just old al (Dec 27, 2018)

To add a thought here - a long time ago I owned a Ford pickup - a 1955. 

The tank in that was supported in a cradle - the cradle bolting to the chassis. Think a set of L legs - the long side bolted to the frame. 

The tank was then supported on the other side of the L, and its mount to the L and the chassis was steel strapping.

Admittedly parasitic weight, but that bugger was NOT going to get loose as long as the though bolts to the chassis held.

I shook a lot of bits off that truck in some fairly inhospitable places, but the tank was never a worry.

Just my two penn'orth - Alan.


----------



## BGHansen (Dec 27, 2018)

I didn't look up the shear strength of grade 5 vs. grade 8 bolts so just guessing here off the top of my head.  Shear is force per unit area.  Back in the day, we'd estimate up to a 30g load because of extremely rough roads or 30 times the weight being supported.  An extreme pot hole was only 10 g because it was a one-time event,

Calculate your cross section area of the bolt(s) and divide that into the weight being supported.  Again, available on-line with a quick fact check, but grade 5 bolts are probably good for around 100,000 psi.  Grade 8, maybe 150,000 psi.

Bruce


----------



## Downwindtracker2 (Dec 27, 2018)

8.8 grade ISO  are about the same as grade 5 SAE


----------



## malmac (Dec 27, 2018)

Bruce, that was the sort of figure I was looking for. I didn't think it would be that high, but would prefer to have a few extra bolts than not enough.  The plan was always to have a rubber mount which would allow for some chassis /tray twist - just trying to work out the best way of applying the help that the group have passed on to me. Much appreciated.
The weight of the fuel will be approximately 145kg plus the weight of the tank which I estimate will be probably about 60kgs - so a 200kg dead weight. 30 times that is 6000kgs momentum. It sure adds up.

Here is a quote from another source about this matter.

"For an M12 bolt on the thread I'd use 10mm as the bearing area to be safe.
Allowable bearing force on 12mm mild steel plate with a bolt diameter of 10mm would be 2.06 tons according to the table I have, 12mm shank/pin would be 2.47 tons. The shear strength of the bolt will far exceed the bearing capability as even an 8.8 rated M12 bolt would have a shear strength of 4323 kg.
The table I'm using has a safety factor of 5 which is the lifting industry standard rather than 3 which some non critical applications use."

So If this is true, then I don't need a dozen 10mm bolts to support 30 times the weight - however I still need to design the interface (straps or what ever) that connect the fuel tank to the tray. I had better go and do some more thinking.

Thanks again to all.


Mal


----------



## BGHansen (Dec 27, 2018)

malmac said:


> Bruce, that was the sort of figure I was looking for. I didn't think it would be that high, but would prefer to have a few extra bolts than not enough.  The plan was always to have a rubber mount which would allow for some chassis /tray twist - just trying to work out the best way of applying the help that the group have passed on to me. Much appreciated.
> The weight of the fuel will be approximately 145kg plus the weight of the tank which I estimate will be probably about 60kgs - so a 200kg dead weight. 30 times that is 6000kgs momentum. It sure adds up.
> 
> Here is a quote from another source about this matter.
> ...


Hi Mal,

Not a problem. We used 10g for FMVSS 208 standards on things like console arm rest lids. Weigh the armrest and pull up with that force. If it stayed closed we were good to go. That was in the 1990's so don't know if the old validation by calculation still holds true.

One of the Milford Proving Ground engineers told me for suspension parts on military vehicles (Hummers) they used 30g which seems high. But if it was my kid in harm's way, the bigger the safety factor the better.

Bruce


----------



## john.k (Dec 27, 2018)

The secret with corrugated roads is to drive fast enough so that the wheels only hit the tops of the ridges.This is how big trucks survive on the roads......If a truck slows ,the corrugations twist and work the chassis and axles to failure in a short time.


----------



## malmac (Dec 27, 2018)

Thanks Bruce. I am busy redesigning the mounting points to make sure there will be no interference when the tray with tank is fitted to the Toyota. Better to have lots of planning before our fabricator starts to knock up the actual parts in metal.

Attached is a plywood mock up of the diesel tank to be built. Yes it will be tweaked but this is the opening iteration.

Mal


----------



## gwade (Dec 27, 2018)

I suggest you look at a phone app called "IEngineer".  It shows the strengths (including sheer) of all common sizes and grades of bolts.  I use it frequently as it also shows drill size and a lot of other pertinent data.  I believe it is free for imperial sizes and a minimal cost with the addition of metric.  Give it a try - I don't think you will be disappointed.


----------



## Downunder Bob (Dec 29, 2018)

Mal you might also consider using resilient mounts, as commonly used in mounting machinery, they are designed to absorb these cyclic vibrations.


----------



## malmac (Dec 29, 2018)

Downunder Bob said:


> Mal you might also consider using resilient mounts, as commonly used in mounting machinery, they are designed to absorb these cyclic vibrations.



Bob, I am open to all suggestions - I will do a search and see what I come up with.


Thanks   Mal


----------



## Forty Niner (Dec 29, 2018)

P. Waller said:


> What is a corrugated road?






This is a photo a friend took recently on a trip out to Western Australia.


----------



## Joe in Oz (Jan 2, 2019)

Hahaha  That's a highway! That's barely corrugated at all 
Below is part of the Gibb River Road. It is a State Highway too, but it will shake your fillings out of your teeth, because the corrugations change in frequency as the soil profile changes. So you virtually can't find a speed at which the vibrations stop....


----------



## Downwindtracker2 (Jan 2, 2019)

Even those ones look shallow ! Those ones on the Mitchell Falls run, it comes off the Gibb, were an honest 20cm or 8" deep.  Luckily I was driving a hire ute. Not my truck. The problem is guys will air down to get the cushion, but the tires then will overheat with all the flexing. They blow a lot of tires on those roads.


----------



## malmac (Jan 2, 2019)

Definitely going with the strap hangers that earlier posts have suggested. Here is a progress report in pics of how I ma reinforcing the mounting points for the strap hangers. Given the 2mm wall thickness of the RHS tray frame I figure the mounting points need to be reinforced. Here is my approach to make saddles which spread the load. Also planning to have three straps rather than just have two.

Thanks again to everyone for your ideas - much appreciated.

Mal


----------



## malmac (Jan 4, 2019)

Here are the six crush tubes and the assembly spacers to ensure the two halves of the saddles get aligned and spaced correctly. Still long way to go but one step at a time.


----------



## malmac (Jan 27, 2019)

Progress on the diesel tank.


----------



## FOMOGO (Jan 27, 2019)

Your doing some nice work there. Cheers, Mike


----------



## malmac (Jan 27, 2019)

I forgot to post this pic. This is actually the tank back from the fabricators. Building the plywood model has resulted in a perfect fit into the location on the tray. This week I will take it down and have it powder coated to reduce rust on the outside. Taped patches on the top are where the breathers will screw in.


----------



## malmac (Jan 27, 2019)

The 40 x 5 mm straps which support the tank have a major shortcoming in design. They may spread the load across their flat surface but they fail to add any support to the centre of the tank. So I am going to weld a bar across in a vertical plane which should help to provide a measurable level of support to the centre of the tank. To lighten the weight of these addistions I plan to drill 40mm holes with a 15mm space between them. The bar will be 60mm x 5mm. My calculations mean a 30% reduction in weight, however I do not know how much I have reduced their load carrying capacity.


----------



## Latinrascalrg1 (Jan 27, 2019)

Nice work.
Fyi, in case you weren't aware.....
They sell chemical tank lining kits that are marketed mainly to the motorcycle world that would be perfect to use to protect against corrosion inside the tank.


----------



## malmac (Jan 27, 2019)

Latinrascalrg1 said:


> Nice work.
> Fyi, in case you weren't aware.....
> They sell chemical tank lining kits that are marketed mainly to the motorcycle world that would be perfect to use to protect against corrosion inside the tank.



I have been giving this some consideration and at the minimum I am adding an extra filter - some of the products I have heard can just mush up and become sludge - so an extra problem. So far have not found a product that I have absolute confidence in.  But I am thinking and thank you for reminding me to revisit the question.


----------



## Latinrascalrg1 (Jan 27, 2019)

Well I wish you luck in your endeavors but i would like to add that  from my personal experience ive seen the "mush" issue when the product wasnt applied correctly by applying to much of the coating instead od several thin coat to allow the previous coat to dry before adding more and or simply not recommending for the material to cure completely.


----------



## malmac (Jan 27, 2019)

Thank you. Exactly which product are you referring too. Also given the inside of a motorcycle tank is reatively small, say 15 to 35 litres capacity and without baffles - I have been thinking how to suitably revolve the 170 litre tank so I can feel assured that I have, 1. completely sealed the inside, 2 I have completely drained out any excess from every possible corner and 3. can ascertain that the product has cured completely and 4. have undertaken all this without ingesting the toxic fumes which at least some, if not all products exude. These points are providing a substantial hurdle for me to overcome. All thoughts are welcome as I am not trying to scrap the idea but rather work through the problems and viable solutions before I get in out of my depth and stuff it up completely.


----------



## Latinrascalrg1 (Jan 28, 2019)

Wow ok, so first I used a product called Red Kote.  My bikes tank was 4.2 U.S. gallons with baffles.  I bought a quart sized can, poured 3/4 can into tank, rock/rolled tank for 10 minutes then drained back into original can (about 1/3rd the amount I poured in came out, also some spillage occured in the process). I waited 8 hours then recoated using the remaining liner fluid. Empty what you can of the liquid then let dry.  
***I would recommend giving it a few minutes rocking/ turning the tank after you drain the liner that is still liquid from the tank in order to help disperse any pudding that might happen around the baffles after each coat.

So long as diesel fuel hasnt been in the tank (you would need to sandblast the metal if it was) you can degrease and rinse and when you think its clean and ready to move to next steps immediately after rinsing 
You can pour in some acetone to dry up the leftover moisture,  drain what you can of the acetone then pour in the Red Kote. 

As for the rest I guess thats something you will need to work out cause i never did a tank that large sorry.


----------



## malmac (Jan 28, 2019)

Thank you for taking your time to explain your process. More thought required on my part. By the way what make of bike do you have? Looks like a Japanese Cruiser, maybe Kawasaki? 
This is my sons bike but I have one that is very similar, I just cant lay my hand on a pic to show you.

Thanks for all your tips, much appreciated.

Mal


----------



## Latinrascalrg1 (Jan 28, 2019)

You're welcome, i just hope i haven't caused you more stress with your project!

On the bike in my picture, you are close, its a Suzuki Boulavard M109R.  

Is that a 60s BMW R60?


----------



## malmac (Jan 28, 2019)

Ah Suzuki was going to be my second guess. Yes that is a 1967 R60. I actually have the R69s version, which is like the spots version, but same frame and just a fe go faster bits.

I have decided I am going to leave the inside untreated and if in a couple of years time it gets uncontrollable rust then I will get a tank made out of aluminium to replace it. I just dont have the time at present to tackle the decision or the implementation of the coating process. It would mean I would have to build some sort of rotating framework so I could effectively rotate the tank - it is quite heavy, but I guess I could just roll it along the ground. I am sure there are solutions. Thank you very much for your ideas and information. Much appreciated.

Mal


----------



## Latinrascalrg1 (Jan 28, 2019)

R69s Nice.  Aren't those sorta rare?  I think i remember reading something  about BMW making less then 15,000 in the 60s decade but im not sure!  Either way nice bike.
My M109R is considered a Power Cruiser and it certainly lives up to that designation.
As for the tank thats of course totally your decision, i was just throwing out a suggestion......fwiw im pretty sure you and a partner would have no trouble gently rocking and Flipping  the tank to spread the liner for 10 minutes or so.
Anyway i wish you luck which ever road you choose to travel.

And make sure you keep the shiny side up on those bikes.


----------



## middle.road (Jan 28, 2019)

What vehicle is this going into?
I'm wondering if mounting similar to a vibratory feeder is even possible.
We use to mount a two cylinder petrol engine up on top of it to power it and the hydraulic pump.
I seem to recall that the fuel tank was mounted on heavy short/stout springs.

OK, the heck with the fuel tank in the vehicle. 
How the devil do you keep your teeth in your head traveling that kind of corrugated/washboard?
I remember some rough roads out in Colorado as a kid, but the picts above make the ones I experienced seem glass smooth...


----------



## jcslocum (Feb 2, 2019)

I have used Caswells epoxy to seal up quite a few used tanks and the stuff is superb. The last tank I did was for a Lotus Esprit that had pinholes and perforations from water in the bottom and a corroded top seam from mice building a nest and peeing on it for years. Cleaned up with acetone and drywall screws inside, I sealed up the holes with tape and poured the magic epoxy in. Sealeup us all the pin holes and larger holes. It’s been is service for 2 years now and no leaking. Granted, it’s not driven on those roads either!

Good luck with you project.


----------



## malmac (Feb 3, 2019)

middle.road said:


> What vehicle is this going into?
> I'm wondering if mounting similar to a vibratory feeder is even possible.
> We use to mount a two cylinder petrol engine up on top of it to power it and the hydraulic pump.
> I seem to recall that the fuel tank was mounted on heavy short/stout springs.
> ...



Hi Dan

This tank goes into a 79 series Toyota Landcruiser. I don't think there are many in the USA - but maybe I'm wrong.

The strategy for travelling on corrugated roads which we follow is, low tyre pressures - like 20 ~ 25 psi and we keep our speed down - so unlike many we don't drive at 80 K/hr - just kills the vehicle.

Here is the Landcruiser as delivered without a tray.

Mal


----------



## malmac (Feb 9, 2019)

Been working on a heat shield to go under the new diesel tank.

Pic 1 - the muffler
Pic 2 - the brackets to create the air gap
Pic 3 - the sheet of stainless I plan to use for the heat shield.

The project edges it's way forward.

Mal


----------



## kvt (Feb 9, 2019)

An old FJ45, land cruiser, have seen a few in the USA/Alaska.  none of them that new.   The 1965 FJ40 I had was one ruff ridding thing.  So I can imagine what the truck is like on those roads. 
Like your project and keep it going.   Those were some tuff old vehicles,  glad to see you keep it on the road.


----------



## malmac (Feb 9, 2019)

WE have some pretty trick suspension under the cruiser and it rides better than our Previous Mazda BT50 (if you get them over your way). Though corrugations are never pleasant.


Here are the straps I have manufactured to hold up the 165 litre diesel tank. I hope this design will help to take some of the load from the cenre of the tank floor rather than shifting all the load carrying effect to the corners. We will see how it sits when she is installed and loaded.


Mal


----------



## Latinrascalrg1 (Feb 9, 2019)

malmac said:


> WE have some pretty trick suspension under the cruiser and it rides better than our Previous Mazda BT50 (if you get them over your way). Though corrugations are never pleasant.
> 
> 
> Here are the straps I have manufactured to hold up the 165 litre diesel tank. I hope this design will help to take some of the load from the cenre of the tank floor rather than shifting all the load carrying effect to the corners. We will see how it sits when she is installed and loaded.
> ...


Id be interested in the specs on the suspension if you wouldn't  mind sharing  your Knowledge?   I have a 95' dodge ram short bed short cab 4x4 that i Absolutely love and want to  restore to road safe condition.  My problem is the suspension is sorta like a wild stallion full of energy and i have a medical condition  that makes car sickness a common occurrence bad enough to keep me from going anywhere unless its a positive necessity.........SO im looking for options to tame the bucking beast aka the suspension system.  At this point i am considering an air bag system for at least the rear axle (hopefully front also) but my only experience with an air ride system is on my bike which was a very positive experience but it's also a much different machine so i could only assume to "possibly " expect a different result?  I figure a rig setup to run on those roads for a large portion of its lifetime could provide 
Some very useful info for me so Any advice no matter how trivial  you think it might be would be Greatly Appreciated.  It might be the key that would allow me to get out into the world more often.
Thanks in advance!


----------



## kvt (Feb 9, 2019)

Your straps look good,  one that I was going to say was either a sub frame or skid plate under the straps with rubber between them and the tank,   then the sub frame/plate would take the center load and hold it.    or at least that was my thinking


----------



## malmac (Feb 10, 2019)

Latinrascalrg1 said:


> Id be interested in the specs on the suspension if you wouldn't  mind sharing  your Knowledge?   I have a 95' dodge ram short bed short cab 4x4 that i Absolutely love and want to  restore to road safe condition.  My problem is the suspension is sorta like a wild stallion full of energy and i have a medical condition  that makes car sickness a common occurrence bad enough to keep me from going anywhere unless its a positive necessity.........SO im looking for options to tame the bucking beast aka the suspension system.  At this point i am considering an air bag system for at least the rear axle (hopefully front also) but my only experience with an air ride system is on my bike which was a very positive experience but it's also a much different machine so i could only assume to "possibly " expect a different result?  I figure a rig setup to run on those roads for a large portion of its lifetime could provide
> Some very useful info for me so Any advice no matter how trivial  you think it might be would be Greatly Appreciated.  It might be the key that would allow me to get out into the world more often.
> Thanks in advance!




Look up ARB BP51's - 



 here is a youtube clip about the system.

We have it is good but it was expensive.

Mal


----------



## malmac (Feb 10, 2019)

kvt said:


> Your straps look good,  one that I was going to say was either a sub frame or skid plate under the straps with rubber between them and the tank,   then the sub frame/plate would take the center load and hold it.    or at least that was my thinking



The tank has baffles which help support the floor from inside and the straps which will have rubber between them and the tank hopefully will do the rest.
Because space does not allow the rear of the three straps to have the full support I have made rubber blocks which sit neatly under the rear strap in four places.

Here are a couple of pics to illustrate.

Cheers


mal


----------



## malmac (Feb 10, 2019)

Here is the heat shield for the muffler completed and ready to be fitted back onto the vehicle. I hope I will eventually finish this work on the vehicle and just go and sit by a river somewhere and have an afternoon nap.

Mal


----------



## malmac (Feb 14, 2019)

Here is the new diesel tank getting the breather plumbing test fitted.

These are the breathers I machined up for the diesel tank and the under tray water tank.

Lots of small steps.


----------



## malmac (Feb 21, 2019)

A question re the filler pipe for the new diesel tank.

I don't have much room between the front of the tray and the cabin of the vehicle.
I did consider running a rectangular RHS filler that was say 60mm x 40mm - so I had more clearence.
But it all got messy with the transitions from round to rectangular and back again.

So I have come up with a precision fitting (as illustrated).

What problems do you see in adopting this approach as opposed to the big chunk of rubber with two hose clamps.
The hose clamps are the real problem. Because to tighten them they need to be positioned at the worst possible orientation.
Right where they rub on the cabin of the vehicle.

Suggestions welcome.

Mal


----------



## stupoty (Feb 21, 2019)

malmac said:


> A question re the filler pipe for the new diesel tank.
> 
> I don't have much room between the front of the tray and the cabin of the vehicle.
> I did consider running a rectangular RHS filler that was say 60mm x 40mm - so I had more clearence.
> ...



Could you install the lines using some sort of flare nuts instead of hose clamps ? They could be attached to the tank before install and have a joint some ware convenient.

Stu


----------



## malmac (Feb 21, 2019)

stupoty said:


> Could you install the lines using some sort of flare nuts instead of hose clamps ? They could be attached to the tank before install and have a joint some ware convenient.
> 
> Stu


Stu

I have thought of flare nuts or the pipe joints that have a left / right thread - but to fit the filler pipe at the front I need it to be conscise size wise.
Yes I could down size to a 40mm pipe but then I severely reduce flow - so to fill the tank which I estimate will hold 135 litres - maybe it would be an impediment.

Mal


----------



## stupoty (Feb 21, 2019)

malmac said:


> Yes I could down size to a 40mm pipe but then I severely reduce flow - so to fill the tank which I estimate will hold 135 litres - maybe it would be an impediment.




Whoops sorry I totaly missed the word filler pipe,  Yeah I can see how that size nut might be a bit difficult..

You could have a few coffees while you filled up though ?


----------



## malmac (Feb 25, 2019)

Things are starting to go back together. Today we secured the tank into the tray along with the water tank and a rear opening storage box.

Also shown are the straps that hold up the diesel tank.

Mal


----------

