Motorcycle Polished Stainless Steel Battery Box

Several things need to be considered when designing a Custom Motorcycle building a battery box.

  1. Size – to allow battery to fit
  2. Shape – for battery fit and also where on the bike it will fit
  3. Mounting method / position e.g. brackets, flanges, bolt fixing, welded to frame, removable.
  4. Will it sit snug in its space and be fixed strongly enough – as a battery can weigh a good bit.
  5. Will it interfere / hit / affect operation of / with other components e.g. gearbox, carbs / throttle bodies, side panels, seat, rear panel, electrics etc.
  6. Can you access the battery terminals easily should you need to?
  7. Consider mounting and positioning so that terminals do not touch or foul and arc onto another metal part of the motorcycle.
  8. Drain, in case battery leaks.
  9. Battery is held in position / fixed by clamps, rubber straps etc.
  10. Do fuses need to be located or relays on the battery box or near to it – is there room for them and fixings to hold them in place?
All these things may be a simple point to note but if you are building a battery box in what ever material you do not want to find that after you have spent good time and money it will not fit and be secured in the designated area.
When we deal with customer requests for battery boxes or trays for cars or motorcycles we very often ask – “have you made a cardboard mock up of what you want to check that it will fit ok”?
Inevitably if not there can be issues of the manufactured box or tray not fitting correctly, hitting or fouling on other components, difficulty locating it, rubbing or damaging frameworks (especially after you have paid a lot of money for a paint job) during fitting etc etc. For a small amount of time messing about with scissors, cardboard & sellotape you can save yourself both time, money and grief.

Battery Tray Customer Drawing

Anyway we recently received this drawing from the customer and had a couple of emails and phone calls to clarify things and make sure he got what he wanted and we could manufacture as a 1 off item at the most economical cost.

One or two bits were redesigned and we ended up with an easier slightly cheaper item to manufacture which was good for all involved.

Once all happy we proceeded to manufacture parts to make up the battery box from stainless steel, this was going to be mirror polished and so during marking out (using scribe, rule, square), cutting out (using guillotine &  cutting disc) we needed to be very careful not to mark the surface.

We used Stainless Steel 304 grade, PC1 – Plastic Coated 1 side, 1.5mm thick, the idea is the plastic coating provides resistance to marking etc during manufacture, we have also in the past covered the whole surface in masking tape to prevent marking. Once all the parts had been marked out, cut out and folded where required it was time to tack weld and assemble all the parts –

Parts ready for Assembly, edges pre polished

Before tacking the parts together we made sure that the edges were pre polished – this makes it far easier when final polishing the parts after assembly and welding.

Tack Welded Panels

As you can see in the above 2 images, “tack up” and “set up” is critical in getting any job right 1st time, It is worth spending a few minutes more at these stages as if not it will take a lot longer to sort out the consequences at a later stage.

For example if the job is tacked up out of square and then welded up you would have to cut out all the welds to be able to get the job squared up properly, time consuming, messy and it will never be the same. If you tack up a joint out of level for example you can get a larger gap one end compared to the other and this may affect the size of the weld where you have welded along and then found you have to lay a larger fillet to “fill” the gap, this can also increase risk of distortion and penetration through the joint, both of which may cause problems later.

So the idea when cutting and forming this job was to make sure that we got our panels sized correctly so that we could achieve a neat corner corner joint at the tack up stage between panels. see B below !


If the joint was not quite set to a corner joint we simply closed down the tack using a small Pin Hammer, this is sufficient for closing the gap down as minimal effort and “weight” is need to do this.

When all parts are tacked together and the joints are all neat closed down corner joints this will be ideal for a neat bead of weld along them, after checking the job for square again.

Fuse Welded Joint

 As we achieved a good set up of the joints we were able to “fuse weld” them together, this is a method where as no filler wire is added to the molten pool of weld, the edges of the material are simply melted together as we run along the joint. If you are an experienced welder you can set up your machine to achieve this easily as long as you get your rate of travel along the joint correct. If not then you will get a build up of localised heat and excess penetration and in some cases a nice hole in the joint just where you dont want it.

I completed the welding of this job by using the TIG welding process which for this kind of  job is ideal as it is a very “neat” and “precise” method of welding when compared to MIG welding .

Polished Battery Box

Using the TIG welding “fusion” welding method I was able to mirror polish the complete job without sanding or blending in the welds as these were “smooth and flush” to the material and looked neat and tidy as they were “laid”.

Unfortunately for me my motor on my polisher died a death whilst trying to finish polishing this job and I had to polish by sander and hand – this took me 3 times as long and still ended up not quite 100% up to my standards. As several sides of the battery box will not be seen when in situ it should be fine though once fitted.

4.5 inch grinder with polishing attachments

For all your Custom Car & Motorcycle Parts Manufacture and Welding / Repairs


Don`t forget to email or call us for all your custom made 1 off bespoke items.

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Threading and Tapping Holes in Metal

A tap

standard 3 piece tap set

cuts threads on the inside of a hole – known as FEMALE threads, to accept a machine screw or bolt. Taps can also be used to restore an internal thread

Typical Internal Thread

that has been damaged or to cut a new, larger thread in the case of severe damage or stripping.

The opposite of an internal thread is an external thread – MALE thread

External Thread

which you can cut using a die

Split Die

Taps come in 3 types – usually as a “set”, starting a first cut, middle or 2nd cut and lastly a bottoming or plug tap. 1st cut has the most taper and is design to start the thread in a new hole, 2nd has a bit less, bottoming will cut threads all the way to the bottom of a blind hole. You can usually get away with just 2nd and bottoming. If you are cleaning out a hole, I would use 2nd or plug tap because there is less risk of cross threading, which is easy to do in a mangled thread.

Dies on the other hand usually come as a Split Die – this is to allow the Die to be “opened out” to make the first cut on a round shaft easier to start (similar to a first cut tap), and then closed a little to finish the thread to a good fit to the nut or female thread.

So to recap a “TAP” is used to make a FEMALE or INTERNAL THREAD, a “DIE” is used to make a MALE or EXTERNAL THREAD.

A TAP needs a TAP HANDLE which clamps the “tap” in place in order to be able to manually turn the tap to produce the cutting action

Tap Handle

These come in various forms, as above or

Tap Wrench

Both types are often called a “TAP WRENCH

If we are going to put a female thread into a part we will need to know what size to drill the hole. In order to do this we must look this up on a “Tapping drill” chart see example below.

Tapping Drill Size table

A good idea for most engineers is to invest a couple of pounds into a ZEUS book which contains many “technical” charts / tables / formula that engineers require – they are worth every penny –

An extremely handy pocket sized reference booklet of data charts and tables for the drawing office, toolroom or workshop.

This metric revision publication is produced by Zeus Precision Charts Ltd, who are members of the British Standards Institution.

The 28 laminated pages contain data on standard drill sizes and decimal equivalents, tapping drills and clearances for metric and imperial threads, BS4500 tolerances, hardness comparisons, jig boring co-ordinates for equally spaced holes, allowances for sheet metal bending and Morse tapers.

Also, long tables for sine, cosine, tangents and cotangent.

Threading a hole is a skill, the tap has to be aligned with the hole and care needs to be taken to ensure that the thread stays aligned with the drilled hole otherwise you can end up with a thread running at an angle to the hole that has been drilled.

When tapping a standard right handed thread you must take great care to “break off” the swarf that is being cut from the inside wall of the hole. To do this we wind the tap in clockwise 1 turn at a time, stop and then turn back (anti-clockwise) 1/2 a turn. It is also a good idea to use some form of cutting compound to “ease” the process.

Typical Manual Tapping

Great care must also be taken with consideration to force being used and resistance being felt through the tap handle. If there is excess swarf build up the the rotary motion of turning the tap becomes difficult and “tight”, this may also be true if no tapping / cutting fluid or compound is used and certainly if the hole has been drilled out too small. As the actual tap is made of hardened steel it is possible to break a Tap off in the hole you are tapping, particularly with smaller taps.

Automated tapping heads are available for pedestal drilling machines, these actually reverse the action before too much pressure is built up thus reducing the chance of breaking a tap.

More than likely though it is worth investing in a good quality Tap & Die set – Recommended is this DRAPER set – if looked after will last a life time.

Draper 79203 37-Piece Tap and Die Set

Click on image to take you to Amazon site

Product Description

Manufactured from carbon steel. Taps and dies suitable for cleaning and cutting threads on mild steel and aluminium. Supplied with the correct drill bits for tapping. Contents held in plastic insert within steel storage case.

We can repair threads in aluminium, mild steel, stainless steel & castings


Don`t forget to email or call us for all your custom made 1 off bespoke items.

Thanks for reading our blog – we hope this has been of use to you.

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Induction Kits and Performance after market filters – do they really give more BHP

Do Induction Kits or High Flow Air Filters really increase engine power.

To understand the principle of filters we can compare an intake system on a normally aspirated 4 stroke engine to our own air intake system. Humans have very High Flow Air intake system with minimal restrictions slowing the air intake. We have hairs in our nostrils and we have mucus lining our air nasal system to trap or capture dirt and dust, this dirt and dust is removed by Cilia (tiny hairs in the lining of the nasal cavity and trachea) which move these “contaminants” back up to throat, which is then coughed up or mechanically blown out through the nose. Still our lungs are susceptible to dust ingress which long term could damage the lungs efficiency.In exactly the same way an engines intake system must have some method of “filtering” the air intake to remove dirt and dust. This is even more critical to an automotive engine as it has no way of removing any damaging dirt particles that may reach the combustion chamber and damage the internal parts of the engine and cause premature wear. If the air is not filtered to a high level before the air charge enters the combustion chamber there could be the opportunity for these particles to damage, pistons, cylinder bores, combustion chamber, spark plug electrodes, injector nozzles, piston rings and so on. This could all lead to premature wear or imminent failure of the engine.

Typical “element” air filter

Shown above is a typical “element” style air filter used in most cars. These are adequate at filtering out dirt and dust but by no means the most efficient when it come down to air flow and performance.

What are we trying to achieve with an after market Induction Kit ?

Many claim to improve air flow, many claim to improve BHP or engine power or torque or all of these.

Mmmmm lets think for a moment !

A bit of science first. Cold air is more dense that Hot air so common sense tells us that cold air will have a higher concentration of oxygen particles in the same volume of air when compared to hot air !  FACT.

Therefore forgetting about Performance Filters and spending wads of dosh – consider getting a cold air supply to your intake. If you want to get more “BANG FOR YOUR BUCKS” you need to be feeding COLD AIR into your intake system. If your intake system draws air from under your bonnet you may well be sucking hot air (engine heat, manifold heat, turbo heat etc etc)  into your intake a BIG NO NO straight away. Now we have a cold air feed or an intake pipe that is drawing cooler air from outside of the engine bay we can consider filters, filter boxes, etc.

There are many differing types of after market filters available, do a bit of research and take time to make a “judged” decision. Panel, cone, paper element, wire gauze, cotton, sponge are all types that could be found to fit your car or bike or truck or whatever vehicle you are looking for ! So now we have considered air supply, lets look at the filters available – Above are a selection of filters you might come across when searching for intake filters By methods of research and testing FLASH CUSTOMS can say from experience that lightly oiled cotton filters offer the best flow rates of any. This is ok but many applications are not covered by these types of specialist filter.

We would recommend for average FAST ROAD use that a modern gauze type filter or sponge filter (panel, cone etc) be used with impregnated dirt re tentative spray, both far better than a standard paper element filter. Only a very slight coating of oil spray will aid filtration. If excess oil is coating the filter this may actually reduce the flow and even worse clog up your MAF sensor (Mass Air Flow) and confuse your ECU, simply making matters worse. Make sure you clean the MAF sensor regularly if this is the sort of intake system you have.

Whatever after market filter you fit, remember one rule of thumb:- the larger the surface area of the filter, the better the air flow.Most after market filters allow for complete removal of the original air box, good and bad arises from this.

  1. You will generally have far more induction “ROAR”, boy racers may love this !
  2.  Better AIR FLOW can generally be achieved with after market filters.
  3. Positioning of “open” filters is critical (due to hot engine bay temps)
  4. A 20 degree rise in temperature can reduce BHP by as much as 3%
  5. Smaller engines sometimes suffer from a POWER LOSS when fitting “free flowing” after market filters
  6. Sometimes it is best to fit a replacement “free flowing” after market panel filter in your standard air box particularly for smaller engine sizes.

So as you can see there are positives and negatives to after market filter kits, getting the right one for your car, keeping intake charges “cool”, fitting in a designated “air box” or open is all things that need to be considered.

Filter with cold air feed pipe

Filter positioned at back of engine where lots of heat will accumulate

A shielded Filter set up, reducing the impact of under bonnet temperatures

Simple aluminium ducting that can be used to direct cool air into the filter

At FLASH CUSTOMS we still recommend a specially built induction box to fully surround the after market high flow filter with a cold air feed into the box. This must be sealed to stop hot under bonnet air entering the box and in some instances I have seen customers insulate this box as well!

I have personally seen many young drivers add a simple after market induction kit mounted totally in the wrong place, open to hot air temperatures with no cool air supply and wonder why it makes no difference what so ever to the performance of their car. But, it makes lots of induction roar so it must be going faster ?

With a little bit of thought and not always a lot of money these sometimes quite expensive induction kits can be made to work a lot better and actually give your car some extra performance.

Another “myth” that some kits promote is “RAM AIR” where simply a feed pipe is mounted in the front grill or under the bumper in the flow of air hitting the front of the car. Ram air systems really don’t work up until you reach approx 100mph (so absolutely no use what so ever in normal road driving conditions. Secondly many performance filters tend only to really work at higher engine revs and will in fact be detrimental to the lower end power band.

So personal conclusions to this blog on after market filters is that:- if you have a smaller engined car go with a high flow panel filter to simply replace the original and make sure that you have a nice cool air feed to the intake. For larger engines if you can go with a cotton gauze filter with a cold air feed and an enclosure to prevent hot air getting into the intake.

A final take on this subject, no matter what you do to your intake system to improve it if the intake manifold is rough, and edges and lumps and bumps in it, has mis-matched joins that do not allow “smooth” air flow you will be wasting your time trying to improve your intake system. Get the manifold “gas flowed” and the make sure that every piece of pipework and join is smooth as can be to help air flow.

Here at FLASH CUSTOMS we tend to prefer smooth bore thin wall aluminium tube to make up an induction pipe run, this is much more efficient at allowing air to flow smoothly compared to other types of pipework such as concertina type aluminium or plastic air hosing.

Smooth bore mandrel bent aluminium tube


Recommended Reading

This work is aimed at the enthusiast engine tuner and race engine builder. Founded on the author’s many years of experience in building, tuning and modifying high-performance engines, it sets out the principles involved in forced induction, supported by tables and numerous illustrations. From basic theory through to building a rugged engine, all the important aspects of supercharging and turbocharging are explained and analysed.


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Carbon Fibre Wrapped Oil Catch Tank.

Wrapping” is becoming ever more popular in the automotive industry. Many effects, colours and designs can be achieved using vinyl wrap. This can be used to change the body colour of a car, or other vehicle, or used in business advertising for company vans, cars and vehicles.

Not only can you change the appearance of your vehicle but a vinyl wrap also helps to protect your vehicle from day to day scuffs and scrapes, swirls and scratching.

Heat activated adhesives backing the wrap material leave no real residue should the wrap ever be peeled off the vehicle and if applied correctly a stunning effect can be achieved for a lot less than a respray and or airbrushed artwork.

We came across a very good company for wrapping  vehicles and parts, they have wrapped a simple alloy catch tank for us to showcase their skills in wrapping smaller items.

The wrapping on this tank is a carbon effect wrap and is an excellent and effective finish. We simply wanted something different and this sure is, I think you`ll agree it looks absolutely awesome.

The beauty of this is that heat should not affect the wrapped finish, should the Oil Catch Tank get hot vapours through it.

John our wrapper gives a few bullet point tips for wrapping parts

  • Make sure your using good quality carbon fibre vinyl wrap
  • Measurements of the item your wrapping, do not cut direct to the size of the item, allow overlap
  • Applying the carbon wrap- clean the item or items before applying the wrap clean this by (alcohol related liquid) and wash thoroughly by cleaning this gets all the grime anything that has attatched on the object, it will remove them which will give you a smooth finish.
  • When you have measured your vinyl then at constant heat with a high temperatured heat gun the glue will then be activated and ready to be stuck to any surface ( you have to know when the vinyl is flexible enough to apply)
  • Work out the bubbles and creases bit by bit, but also making sure the vinyl doesnt skrink too much around the object.
  • Any overlap may be cut/sliced with a sharp tool
  • A lot of patience time and skill is required for a great outcome.

 If you would like help in getting your car, vehicle or parts wrapped you need to contact John email –

Don`t forget to email or call us for all your custom made 1 off bespoke items.

Thanks for reading our blog – we hope this has been of use to you.

Recommended sites

FLASH CUSTOMS – Specialist Custom Car & Motorcycle Parts
Loaded Wallet – Discount and cash back offers
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