Possibly silly question regarding bash plates!
 

Quick question for anyone in the know regarding bash plates / sump guards.

Almost all of the bash plates available are made from 4mm Ally, I assume for lightness, what would be the issues of having one made from stainless steel instead?

I am owed a few favours by someone that works with stainless steel for a living, and he has offered to knock me up a bash plate to my spec free of charge. I appreciate that it would be heavier, but a bash plate is not a huge item so I am thinking the weight saving from a purchased plate compared to a free stainless steel plate would not be enough to warrant paying for one, but is there anything else I should take into account. Also any idea what thickness I would need to go for on a steel plate as opposed to ally?

Thanks in advance

Steve

Only other issue I can think of apart from weight is rust. Sure you will paint it but it is going to get bashed and will without doubt start to rust.

I know several people use steel so it isn't like it is a serious no no or anything.

possibly silly question regarding bash plates
 

Rust ? He's talking stainless steel !
I would reckon 2mm of steel would be as strong, maybe stronger than ally.

The weight advantages of ally aren't that great if the steel part is designed correctly. KTM use steel frames that are quite a bit lighter than some alloy ones. I think regidity is an issue, although this could be sorted with some well placed creases or corrugations.

2mm Stainless might just be very nice. I'm sure you can find out what the weight would be.

One point though - alu. alloy absorbs impact by deforming: stainless is very strong. Would this strength transmit shock impacts directly to your frame?

Yes indeed
 

Exactly. The alloy will absorb shock and stretch a bit. It will not transmit the force and thus punch the frame, but also it will take many, many impacts and still be there. Linzi.

Although I am not fitting it to an engine, I am planning to make a bashplate out of plywood.

For a bike, P-clamps to the frame and its secured.

Its light, strong, easily replaced, and absorbs impact well.

I will make a plate for the underside of my sidecar from rectangular sections on a steel flatbar square frame bolted on rubber mounts.

Not pretty but very easy to work with and does the job. Food for thought...

Damn
 

Damn but I almost mentioned ply there myself. I have been with a friend today discussing a sump and rear oil filter guard for my Guzzi for protection against thrown up stones. He mentioned Ply: lightweight, won't screen against heat loss so much ( my bike's air cooled) and it's resilient. The guard would probably be best if it was progressively destroyed after a few impacts, then replaced. Linzi.

In most cases it seems a serious bash plate is not really needed

plywood?
 

thats an interesting suggestion warthog. as a trainee furniture maker i use this stuff now and again and think that a bash plate is the only thing its good for! :thumbup1:

I wouldnt suggest using any 'real' timbers as the engine heat would dry them out which would cause them to bow.

As far as alu. vs stainless steel good points made. how about mild steel (carbon steel)? you would have to paint to protect, but it would absorb impact as it is quite soft compared to stainless.

Materials
 

For bash plates the deformation of alloy makes it very suitable indeed. Mild steel doesn't have the same ability to absorb energy in big strikes. You're more involved in furniture than I am as I only use it but surely you are doing it an Funny how different peoples' views can be. Hell, some people don't like bikes!!!!!!!! Linzi.

Aluminium is brittle compared to steel. Alu will break and steel will bend and can be straightened again and again. It'll probably be a little heavier for the same strength but as said, can be straightened with a hammer or a stone.

Try straightening a piece of aluminium. It will break.

Desert racers
Why?

Hardness
 

Sort of, it depends on the grade of alloy used. Some aluminium alloy is soft, that's the type I'd use. Linzi.

Ply wouldn't sound as hardcore on gravel roads with the rocks bouncing off it but maybe thats an advantage.
Ally transmits heat quicker than steel so perhaps marginally helps an aircooled engine whereas a ply guard would insulate it.

Whichever is chosen, I'm not sure that the insulating/conductive qualities are so important. The effects are margnial IMO.

SS or Alloy may conduct heat bettrer but they are also shiny so they reflect heat radiation back toward the engine. Ply may insulate, but is opaque so does not reflect any heat back.

More importantly, where does an engine generate its heat and where are most of its cooling design traits? The cylinder; some way from the sump... My guess is that engine temps on a moving bike would not differ that much.

Having said all that I would probably choose Ally over ply. In my case its for the sidecar undercariage, and ply is a lot easier to work with than ally and a lot cheaper too. No contest for me, even if it may not look as cool...

Afterthought - Mollydog's comments on steel bashplates make me think that 1.5-2mm mild steel would deform well under impact and has all the benefits of being easy to weld and shape. Good paint will stop rust.

Guilt
 

Please ignore my comments on temps as they only apply to me and my bike. I put a deep sump on a guzzi and fitted an oil filter to the rear of it. The sump is now very low and the bike is vulnerable to stones thrown up in a third world situation, not in Europe. I want to use the bike once in this situation and it'll be summer so the temperature and protection apply to me only on this one trip. Appearances don't matter so I'll use a sheet of ply and chuck it away after the trip. I guess it should be called a stone guard. I was in New Zealand a while ago and ungraded roads wrecked the floor pans and exhaust of cars on them which made me think about the poor oil cooler! Linzi.

My CCM came with a factory fitted stainless steel bashplate - just a simple flat sheet that covers the bottom of the engine and bends up at the front to protect from stuff thrown up from the front wheel - no side wings etc. It's 2.1mm thick and weighs a ton (you have to take it off to change the oil).

I turned down the offer of a new stainless plate with wings and other bits from someone on the owners club site because of the weight.

2.1mm does seem to be overkill and enough to protect against just about anything that the bike is likely to come up against (although I admit that I'm no expert). Anything that would get past the plate would most likely have completely wrecked the engine. If it just to stop stones etc from damaging the crankcase then half the thickness would probably be good enough.

Ask the 4WD guys, they prefer steel rims over aluminium, because steel will bend rather than shatter and can be bashed back in shape.

Thanks everyone for your input, looks like stainless may not be a bad option after all, will see how it goes and post a few pics if everything goes to plan. :thumbup1:

no worries linzi, its a good point you made. only used mild steel once to make a botel opener years ago in high school lol even then i remeber thinking "could i use this to make a part for my bike/bicycle" haha

What do I know?
 

As others have said mild steel doesn't tear, unlike alloy. I am simply a huge supporter of people who use materials in ways others haven't thought of and wood is one such. Much underestimated ply is environmentally superb. Linzi.

Ply would work fine for a while but won't cope well with being wet then dry, hot and dry on one side and muddy and wet on the other. Also quite good at soaking up oil which will make it go soft. Might reduce the oil stains on your kitchen floor though :innocent:

All good
 

Yes indeed but I only want stone protection for one trip to north africa--you suggesting Guzzies leak oil then?

No, just a reference to my Wife's unrealistic objections to motorbikes in the kitchen. Do Guzzies leak oil then ??
The one that I will never be forgiven for is walking a big dollup of the black crud that collects on the frame near the front sprocket, into the hallway and up the stairs; approx. 20 mins after the carpet fitters had left
:oops2:
Being a chippy and having some experience of plywood boats, I think a good lump of ply as a stoneguard is a cool idea. When I was involved with F1, they had odd bits of ply stuck on the floorpan of the cars as sacrificial guards.

The biggest problem with plywood will probably be its inability to "slide", thats the area where steel might win out over aluminium.


Maybe :cool4:

Hello there,

I am a student aerospace engineering and I've learned a thing or two about material properties. Steel is about three times stronger than aluminium and three times heavier. (Depending on which types of course) The reason aluminium is mainly used to make airplanes is a combination of material properties, but the major reason is that because you need only one third of the thickness of the aluminium version if you use steel, you will have more buckling when the material is under compression, because it is so thin.
So you could use a stainless steel bash plate, and it could be one third of the thickness of a aluminium one, but make sure that it is thick enough to sufficiently resist denting, because you wouldn't want it to bend against your engine with every little stone.
The reason that most bash plates are made of aluminium are probably, weight reduction, corrosion resistance (stainless does not mean that it does not rust!), ease of production/manufacturing and looks.
Another alternative would be plastic bash plates, which can even be stronger than metal ones, provided the correct type of plastic is used. Another would be carbon/kevlar composite, which would be the best way to go, carbon is really very strong, but also brittle, when you combine it with kevlar, it is very strong and no longer brittle, and it is much lighter. The only downside is that it is slightly more difficult to repair (though not very difficult).
Wood on the other hand is an excellent material strength wise, and it is also very suitable for airplanes, the reason it is no longer used for that purpose is that it is more difficult to manufacture, it needs much more maintenance and is not that resistant against outside influences (warm/cold, fire, water etc.) This also applies for motorcycles of course.

So, you could use alloy or stainless steel if you'd want to without much difference in use. If you'd want something else (or better) go for a composite material and if you go for wood, do not expect it to last long.

Just my view on things,
Habicht

Plywood is a fantastic material especially layered up with balsa (proper aircraft type). This really needs hot bonding, so isn't easy at home. For wooden items at home, try covering in fibreglass resin. It's a true carbon based composite too, so you can impress any rice rocket power ranger type mates down the pub :clap:

Andy

Chairs
 

I'm looking for an old school chair made of ply. They had a good width and a handy curve. I envisage cutting it off so I have a flat panel with an upswept front. This will be perfect for my bike's shape and the fact that it's recycled and environmentally sound pleases me no end. It's only going to be used on unsealed roads at worst. ( Famous last words, adventurer in blood). Linzi.

I don't think you need the chair. Plywood is really easy to shape, just soak the wood in water for a couple of days until it is soft enough to bend it to the shape you want. Bend it over something which has the form you want the plate to be and fixate it with a clamp or whatever suits. Than leave it to dry completely, you can put it close to the radiator or something but do not try to dry the wood to quickly, e.g. by using a heat gun.

You don't need really thick wood, 4mm should be ok. It you want to laminate it with glassfibre 1.5 - 2 mm should do.

OK this is my personal simplistic view...

Owed a favour.... mate works in SS.... free bash plate to my spec...

Bit of a no brainer IMO. Weight means nothing taken out of context... you ride in mud, bike gains 10kg, rider fat(ish) like myself...few kg you can't shift quickly... bash plate a bit heavy, doesn't even count in my books.... especially as it'll be a top class job, not the garbage welding you pay for off the 'net. Get your mate to machine some location clamps that are fixed to the frame & you have a bargain.

RTS

i agree, go with the ss as i dont think you can have a guard thats too strong, just mount it on rubber mounts, that will help take the shock from impacts.
Iv used both steel and alloy tank guards on my rally car and the steel lasted alot longer against the gravel rash and also never got bent half as bad.

as for composit materials, they are great for impacts but get very shredded and look real tatty after very few scrapes, but if you put a thin alloy protector over the composit guard then you have the best guard available. (short of titanium)
cheers
chris