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240 Motorsport preparation details.

SpacSpac @Spac Canberra-ish.
edited October 2019 in Articles & Guides

Having recently bought a rally car that was built by inexperienced motorsport people, I realised that there's lots of tricks and tips that most people take years to learn.

This series of posts are NOT intended to be a blow-by-blow of how to build a race car from scratch - they are just a few pointers that will hopefully help people's builds be neater, safer, and/or more reliable. And will draw less negative attention from scrutineers...


Cable ties are your friend. They obviously have their limitations, but anyone who is negative about them is dreaming.

  1. Buy good quality ones in bulk. Buy a variety of sizes. Buy enough that you don't feel like you need to conserve them. Electrical supply places are usually far cheaper than your local hardware store (even the big warehouse ones) or car parts place.
  2. Cut the ends off flush, using a good set of electronics cutters. The cutters pictured are about $12 from your local Jaycar - worth it compared to tearing your skin open on a poorly cut cable tie!
  3. When you have to cut of a cable tie, get into the habit of cutting the tail just below the head. This leaves most of the cable tie re-usable: Despite what I said about not conserving them, when you're desperately trying to patch up a busted car in a panic, being able to re-use the old cable ties might just be enough to avoid a DNF.
  4. Feeding a series of them through in the same direction gives a noticeably neater job than just putting them though in whatever direction you like.
  5. Space them evenly. It is neater and helps to avoid stress points.
  6. If you are adding a wire to an existing loom, cut off the old cable ties and incorporate the new wire into the loom. When you simply add extra cable ties over the whole loom, it becomes a nightmare to trace any single wire, and can create weird stress points.



  • SpacSpac @Spac Canberra-ish.
    edited October 2019

    Photos top to bottom:

    1. Skin tearing cable tie that’s been cut using pliers or big side cutters.
    2. Done better!
    3. Cutting so the left over can be reused if you need to.
    4. Cutting to waste the whole lot.
  • SpacSpac @Spac Canberra-ish.
    edited October 2019

    Random tidbit: Current Apple software seems to not get along with OzVolvo, particularly WRT photos.

  • SpacSpac @Spac Canberra-ish.
    edited October 2019


    Not all suppliers are the same! Here's a series of photos of the cage that came in the new rally car, and the Bond cage that is in the race car. They're both BMW 318TIs, so it is a direct comparison.

    Note that the non-Bond cage is from one of the better known suppliers AND it cost more than the Bond one...

    A) Large gap between hoop and body.

    Bond has a smaller gap. As well as the obvious safety improvement, the smaller gap also gives more room for the occupants.

    B) Bolt ends pointing back at the occupants. Simply flipping the bolts around gives a bit more clearance and a flatter surface if a helmet or human body part comes in contact with it.

    Also note the dome headed bolts in the previous photo, which are even better.


    C) Not great leg design, The front leg could angle forward to meet the floor around where the chubby finger is. This would make getting in and out of the car easier and provide slightly more protection in a big front-on impact.

    This photo shows how Bond do it (albeit with a much higher, circuit spec intrusion bar undoing the good work of the better front leg design.

    Both cages are CAMS state level. Both designs would need a Sainz bar to meet the national regs, so there's no advantage to the first design.

    D) Not a great intrusion bar design, IMO.

    Being angled up so steeply has two bad points. The first is that your elbow hits on the bar - not only is this uncomfortable in general use, it also can also cause serious, permanent nerve damage in a decent impact.

    Secondly, it leaves this part open - not such an issue in a circuit car, but in a rally car it is a big exposed area if you go sideways into a tree stump or rock (noting that the most recent Australian rally fatality involved this sort of impact).

    Ideally, a rally cage would have a bar down low and parallel to the sill panel, and a higher one that is either parallel or angled slightly upward at the rear.

    A circuit car wants a bar that is parallel to the sill at the approximate height of the bumper bars of the other cars you are racing against.

    E) Front leg is still not ideal. The extra bends reduce strength and reduce occupant head room.

    Better design - bar is straight in the horizontal section, and follows the body more closely.

    F) My greatest bug-bear - bolts going down through the floor.

    In a rally car, the threads get hammered from rocks off the wheels. This damage is after one event!

    In a race car, there's also the increased risk of the protruding threads getting caught on the trailer.

    In both cases, there's also more risk of damage in an off-road excursion.

    The ONLY reason you wouldn't do this \/ , is if the driver or navigator can put their foot on the expose threads which might punch through their shoe in a big impact.

    I don't want to sound like an ad for Bond, but the simple reality is that their cage is MUCH better. As well as the design aspects I've mentioned, their front legs are made from larger diameter tubin which is both stiffer and stronger. They also use 10mm bolts instead of the minimum required 8mm of the other cage.

  • SpacSpac @Spac Canberra-ish.
    edited October 2019


    First up, read Schedule I in the CAMS manual.


    This car had the inner lap strap mounting points too high.

    The hole at the edge of the body tar is where is was originally mounted, It was maybe 20* from the navigator's body, where the start of the acceptable angle is 45* (and ideal is 75~85* from horizontal).

    Now it is more like 60*, depending on who is in the seat.

    A not-great photo of the driver's side. The original hole was near the top of the tape on the right of the photo.

    The crotch strap mounts were also back, roughly in line with the new lap strap mounts, when the regulation is that they should be straight down, +/-20*.

    Again, none of this is to criticise the previous owner - it just to point out where a few years of experience has shown me a better option.

  • Hi Spac,

    A very good start to what I hope is a comprehesive set of articles. Your comments on cable ties are right on the money. I've no idea how much blood I've wasted on cars where they haven't cut them off neatly.

    As for Bonds, Peter et al just do the best cages for the money. I've got a full FIA spec cage in my Volvo from them, built for an international event. Very well built and well priced. I wouldn't go anywhere else.

    A couple more thoughts:

    Weight is your biggest enemy. Do what you can to minimise it. Cut off bolt ends, drill holes where you can without compromising strength. Take tools you need, not the whole tool roll. Same with spares: take the essential ones.

    Shocks are your friend: get the best you can afford and maintain them.

    Remember it's a rally car and it will get stressed. Look at others who rally similar cars and see where they've reinforced them.



  • this will make using cable ties much easier generally and once you get use to them a lot quicker and neater.

    Paint pens are your best friend if working with others, have your own color ( mine was red) and always dab a little on all bolts when you have tightened them, get your work partner to check and put their paint mark on the parts.

    Magnetic parts trays that can hang on the side of the your vehicle are the best thing when fixing something in the pits and your trying to do shit in a hurry. It also stops stuff going missing or parts all of a sudden turning up mysteriously.

    Always drill a 6mm hole through your thermostat on the fixed part if it doesn't come with one, too many engines have died a painful death through a dying thermostat.

    If you have sponsorship, get someone with the ability to put the stickers on properly and straight, makes a bloody big impression with the money man! (we had $2500 in sponsorship from BMC, Motul and sugarless confectionery, it all helps)

    Make sure you have fun, nothing worse than busting a gut and being shitty because things didn't work out the way you wanted them too. This thing above ended up coming 3rd in class (2F) in a 1 hour race at EC, Scooter was the only 1600 in the field but didn't break anything and ran perfectly for 1 hour revving up to 7950 rpm. Preparation with a tiny bit of luck goes a long way.


  • SpacSpac @Spac Canberra-ish.

    Fasteners and fabrication.

    A) Self tappers and tek screws are not your friend. They should be avoided at all costs. Their main failings are that they inevitably work loose and they love to tear open skin - but they're also not very good at actually holding things.

    B) Rivnut / Nutsert guns are cheap and vastly better than self tappers. Buy the good inserts with the bigger flanges and the knurling on the shank.

    Use loctite on the shank to ensure they don't spin. This is not always needed, but if it is mission critical and/or going to be a particular pain in the butt if it does spin, then its a bit of extra insurance.

    If you find that they're spinning even semi-often, then revise your technique. I've found that drilling the hole slightly undersize (eg: using a 9.5mm drill bit instead of the recommended 9.6mm one) massively improved my success rate.

    C) Drill your holes oversize. It always feels great when you make something and the bolt holes line up perfectly, and the 10mm bolt fits beautifully into the 10.0mm hole you drilled ... but stuff always ends up moving, getting bent and/or corroding. And then those lovely, tight-fitting bolts become a nightmare.

    Going 0.5mm oversize minimises these issues. Some applications, like gravel rally car sump guards, will want to be even larger.

    D) When making brackets and stuff, think long and hard about how strong it needs to be, and the consequences if it breaks. Think about how it will withstand normal use, abnormally hard use and a crash.

  • If there is one single recommendation I could make for competition, it's to use safety wire on EVERYTHING. I have seen all manner of things come off cars on the track, including brake calipers! I once had a caliper bolt work loose, but it did not back out because it was safety wired. Using it increases the time to change things by 30% or more, but it is absolutely worth it. If you safety wire only one item, make it your oil drain plug!

  • SpacSpac @Spac Canberra-ish.
    edited January 2020

    Fitted some boot hold-down springs to the MX5 today - thought that it might be worth doing a 'how to' on these because a surprising number of people screw it up...

    I like these on motorsport cars because they are simple, reliable and they avoid a repeat of the incident where the 244 rally car's keys were locked in its boot thanks to a service crew member trying to help. I have had a number of cars' boot latches get full of dust and either refuse to latch, or become very difficult to open.

    Obviously these springs are not a good option for road cars that require any sort of security. And don't be tempted to fit both, 'cause that's the worst of both worlds.

    These are chinabay copies of the Sparco ones. They do the job are well as the real ones, but they will get surface rust on the stainless springs over time, and the 6 year old Chinese kid who assembles them screws the brackets too far into the springs causing them to sit badly on the bodywork.

    The one on the left is how they come out of the packet, the one on the right has been 'fixed'. This is a way harder job than it would appear, because unscrewing the bracket tightens the spring onto the bracket and locks it all solid.

    Proper ones don't have this problem, but its $45 vs $15 too...

    Work out where you are going to mount them! This one is about the easiest I have ever done - plenty of meat on the bootlid, and plenty in the top part of the rear bumper.

    This photo is meant to show how much cavity space there is between the boot skin and the inner frame. Makes life very easy.

    Remove the original boot latch components - having to manually unlock/release the boot every time you need to open it, will wear thin quickly.

    Locating the brackets evenly/equally is important for avoiding the job looking like crap.

    I forgot to take a photo of sitting the assembled spring up against the car to make sure it was all going to work, but you should do this!

    Again, the MX5 was super easy with a nice edge to measure off.

    I don't use the pop rivets that come with these. They're waaaay too long and simply don't work. This is one task where my hatred of self-tappers is forgotten. If there's any chance of dragging clothing or body part across the end of the self tapper (inside the boot), then either don't use self tappers, or cover the pointy end of screw with a short length or rubber hose.

    Two important things in these two photos.

    First is that I've hooked the spring onto the lower/looser of the two options. This means if the spring is stretched/fatigued, you can do to the tighter/higher hook position.

    Second is that I've marked only the top mounting hole on the bootlid.

    And drilling the pilot hole.

    And then that hole is used for the BOTTOM mounting point. Doing this gives a good amount of spring preload for a mostly horizontal bootlid.

    The more vertical the bootlid is (like a wagon tailgate), the more preload you need but this method has served me well on numerous cars now. There comes a point where these springs simply won't be capable of holding something like a 245 tailgate shut.

    And done. I like to use a straight edge across the mounting points to locate the second set of mounting holes.

    Some people prefer to mount these 'upside down', so the spring is mounted to the body and the clip moves with the bootlid. Their reasoning is that these hooked finger holds could catch a person's eye or nostril.

    I don't do this for two main reasons:

    A) Most cars move the bootlid up and forward, away from soft human parts, so the risk of this actually happening is very low - I've never seen or heard of it actually being a thing. Even on the MX5 (which is low to the ground and has a short bootlid), the resting position is comfortably above my head height.

    B) Closing and opening the bootlid is far easier - you simply grab the hooks and pull down. You can do both hooks at one, or if you only have one hand free, you can do one side and then the other. The 'upside down method' requires one hand to close the boot, and then the other to hook the spring - not so good if you are in a hurry and/or have something in one hand.

    As I said, the MX5 was ridiculously easy. Many cars are more difficult. The BMW hatchback needs them mounted on an angle.

    I haven't worked out a nice way of mounting them on a 940/960. Current thinking is to drill a hole through the bumper bar, and mount them upside down with the springs bolted to the body behind the bumper. Still needs more thought before I commit to anything.

    Occasionally you'll see a Swedish or Norwegian 940 rally car with the springs mounted above the tail-light, and on a very shallow angle - and these cars usually seem to have the bootlid bouncing partially open through the stages, so I'm not doing that!

  • gavinhGav @gavinh Parmelia, Perth
    edited January 2020

    Great post, I'm a sparkie and it's a pet hate to see badly cut cable ties. Have you ever felt the rath of bady cut stainless steel ties, they maise well be razor blades your catching your arms on.

    On a side note I'm looking at getting a car ready for a veriety bash in 2 years (a volvo 122s 4 door) I was looking at installing a single roll over hoop or a 3 point cage? Over to the rear parcel shelf. Is there any pointer @Spac you can give.

    Cheers Gav

  • SpacSpac @Spac Canberra-ish.

    i have copped a couple of poorly cut stainless ties on CV joints - not been opened up by one, but it is easy to imagine!

    How many seats will it have in it?

    If only two, then definitely suggest getting a CAMS spec cage. Along with the safety of being built to a standard, it will make the car/cage far easier to sell later.

    And my personal advice is to NOT buy from AGI.

  • gavinhGav @gavinh Parmelia, Perth

    It will be a 4 seater, after doing the bash plan is it will be my run round car and have some fun with it

  • SpacSpac @Spac Canberra-ish.

    Depending on your plans, sus out whether you actually need a cage.

    When we did the 65 Roses CF bash a few (13!) years ago, the supp regs made a big fuss about needing an approved cage. We got a proper half cage built, got the car engineered, fronted up and discovered a few things:

    1. Only about half the field had any sort of cage fitted.
    2. Our cage was WAY better than most of them.
    3. The nature of the event meant that (I think) the cage was a waste of time anyhow.

    On #3, I will never discourage anyone from fitting safety gear, and big distances over long days in unfamiliar terrain does increase the risk... but fundamentally we were just driving along at the speed limit on good dirt roads. The crashes we were likely to have were unlikely to be helped by a half cage.

    So... assuming that you want to go ahead with a cage:

    Unless there’s a loophole I am unaware of, to be legal with road authorities it will basically have to be a glorified cargo barrier (which I would strongly recommend in any case).

    In that case, I would get a half cage that mounts behind the rear seats and has two good stays back to the rear floor. Even though it is no good for CAMS motorsport, I would build it to CAMS Schedule J specs because anything else will forever have a question mark over it (there are other ways that are perfectly ok, BTW).

    I would also recommend at least one diagonal member in the hoop, and for the rear legs to mount on the horizontal section of the hoop (not down lower on the more vertical section).

  • Not sure i follow with what you mean by "behind the rear seat". I kinda get it for a ute or a wagon, but what about a sedan?

  • SpacSpac @Spac Canberra-ish.

    Dang, been thinking too much about 122 wagons and got my wires crossed!

    Pretty much an impossible task to get any sort of cage legally into a 4-seater sedan or coupe nowdays.

    The street car guys have probably got better ideas of work-arounds than I do.

  • gavinhGav @gavinh Parmelia, Perth

    Hey appericiate the advise, I think it's ok to have a cage in a pass car as long as it doesn't have any extrusion bars that block the door, or you can strike your body on? But would have to check. It's a while off yet but I'm going to try for a year to get the car road worthy etc.

  • SpacSpac @Spac Canberra-ish.

    There's also requirements about head clearance that are impossible to meet in most cars.

    Then the NCOP adds a very lazy line about "nothing in front of the driver", regardless of the clearance.

    While I understand what the rules are intended to achieve, there's a gulf between what is written and what makes sense.

  • Have to agree with you on the bond roll bars. Very tight to the body , top quality.

  • SpacSpac @Spac Canberra-ish.

    Attitude/philosophy to building a motorsport car.

    Been kicking the idea of this post around in my head for a while now, but was finally motivated by some new blokes at the Deputy 4hour Enduro yesterday. They'd built their car on a budget and appeared to have spent their limited money wisely.

    EXCEPT... they'd also bought a super-bling billet quick shifter that "cost more than the car"... This sort of thing happens all the time- people pour money into "cool" parts that offer no real benefit.

    I also see a lot of well-meaning advice instructing newbies that they "must have" things that are absolutely optional.

    Building race cars is fun and we all love cool stuff, but the reality is that none of us has an unlimited budget and it is easy to get lost... so here's my list of priorities.

    A) A car that passes scrutineering. If they don't let it on the track, then you've wasted your time and money, simple as that.

    Make sure the car meets the safety standards, meets the class rules, is built to an adequate standard, and is in acceptable condition.

    B) A car that meets YOUR safety standards. Lots of people love to moralise with idiotic statements about "Never compromise on safety", but those statements are stupid and unhelpful - you're increasing your risk by competing so you've compromised your safety right from the start.

    What you really need to do, is have a long, hard think about the risk vs reward that you are comfortable with, and ensure that your car and your driving fit in with that.

    C) A car that will make it to the end of the event. A slow car that keeps running will always beat the fast car that breaks down (with few event-format-specific exceptions), and more motorsport is more fun, right?

    For example, If you work out that your car regularly breaks the diff, then fix it before you go spending money on anything else.

    There's an old saying that goes "Fast, cheap, reliable: choose any two", and it is worth keeping in mind when you're planning on winding up the boost or whatever.

    D) A car that you can afford to keep running. Sure you can scrimp and save and buy/build an awesome car, but keep in mind that the more serious the car is, the more it costs to keep running.

    This also applies to your choice of car to build. I would love to build an Amazon rally car, but I don't want the hassle of chasing 50yo panels and suspension.

    E) Stuff to make it fast. Exactly what that is, depends on the car and the events you're going to.

    F) Bling. I want to say that shiny things are irrelevant but they're not completely so. Firstly, a pretty car keeps scrutineers happy, and secondly it is easier to work and and stay enthused about a nice car than a shitbox.

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