- My model of MX-5 is: NA
- I’m based near: Chesterfield
- I’m looking for technical help or recommendations on: Bolt Sizes
Fitting my JR CAI that I bought last year. I’m about halfway through the install and I need to take the lid off the airbox to put the filter in.
However the Allen bolts that I need to undo don’t fit anything I have in the garage. 2mm is too small, 2.5mm is too big - and it seems after Googling it, that 2.25mm doesn’t exist.
Did the Americans make these bolts imperial? Even though the rest is metric? Or am I facing every bolt on this lid being manufactured wrong?
The US Imperial is also different to the real imperial isn’t it? So wouldn’t I need to buy a specialised set for this?
in tools the imperial sizes should be the same
I’d have thought they would have been metric, are they mashed up be previous attempts by other owners?
Imperial is Imperial. On this side of the pond we inherited the entire system from the UK. Then refused to swap back to metric later…or rather I should say that adopting metric in the US has been slow. I personally have full sets of both metric and imperial tools since I work on cars that were made decades apart. In general though…I don’t know of any parts company that mixes hardware from two different systems…either all hardware is imperial or its all metric….but I was wrong once.
No! volume (gallons) are different
Ah, you are right. Strange, never noticed that before.
They were bog standard imperial. Maybe I should’ve tried that before posting like a tit 
I’ll repurpose this thread for the final (I hope) issue I’ve run into. Fitting the sodding thing.
Some people have said on various forums over the last 20 years that they needed to trim down the fan housing to fit the airbox itself. It usually isn’t necessary, but is known to be an issue in some cases depending on the cars age etc. “apparently”
That’s the hurdle I’ve hit. It’s looking like I need to trim part of the fan housing down so the airbox can drop in snuggly. I have limited tools, still relying on my dad for a few things, however I’m trying not to bug him too much as he “doesn’t understand what was wrong with the cone filter” and disapproves of how much money I’m spending on the car 
.
So does anyone have any experience with trimming the fan housing? What can I use? and even better, how much do I need to take off? I tried measuring a rough idea just now but I could barely see a thing considering the engine is pretty much back in one piece now - hoses and all.
Project cars am I right? …
While I have zero experience with this intake…I have been modifying cars for decades. Fan shrouds are generally made from ABS plastic. For that type of trimming I like to use a mini router for wood, but you can use a lot of different tools…even a small hand saw or even a file depending on how much material you need to remove. You are almost certainly going to need to remove the shroud to cut it though since you likely have no room to work with in the engine bay without the risk of hitting something else. As for finding out how much you need to cut…in general if I don’t know I will cut up some poster board(best) or some other cardboard into the shape of what you are fitting, then try to fit it in place, then mark the poster board where needed and cut again till it fits. Then if you find you have cut 1/2” from the posterboard to make it fit…you will know you need to cut 1/2” from the shroud….Just an example but you get the idea. It’s hard to give you any more details without a picture of the part and the space you are trying to fit it
Annoyingly, this is the only photo I have of the area. The airbox is to fit directly between the fan housing and the block.
However, the arm that is closest from this perspective (the 2 o clock position if you were sitting in the driver’s seat) is the reason it doesn’t quit fit right now.
The culprit is that Aluminium radiator I have. Both the radiator and the intake are designed as OEM replacements, but their compatibility with eachother isn’t listed; even though I did quite a bit of reading and bought that specific item because it had the best chance to fit with the intake.
We are talking about needing to take off maybe 10mm maximum. Certainly not enough to remove the arm completely, otherwise I wouldn’t do it as it would jeopardise the strength of the fan housing itself.
I suppose my other option would be to buy an aftermarket fan that is slimmer than stock. Getting dimensions for aftermarket is easy. But I am genuinely struggling to find dimensions for the fan housing itself because my car is a non-A/C example, which is a different part entirely.
I am away from home for work, otherwise I’d just measure it with a ruler. But I don’t have one long enough to cover the 105-mile distance
I’m at that point where I’m reluctant to modify due to inexperience (and the fact I’ve already had to call for help twice because of snapped bolts), but also don’t want to waste money buying a new part that doesn’t fit.
I have a couple ideas here: Since yours is a non-AC car does that mean you only have the one fan? If so the solution is pretty simple…just move the fan to the other side of the radiator. You would just need to extend the fan wires to reach. It would take a couple feet of wire, some wire crimps and about 5 minutes. I am fairly certain it will fit the threaded bosses of the radiator just fine regardless of which side you put it on.
Failing that, you can simply trim fan shroud just a touch at a time. Try to fit the intake, mark the shroud where it seems to be touching, trim it back. I am pretty sure 1cm isn’t going to make any structural difference to the fan shroud, I have taken more off of fan shrouds myself. The whole point of the shroud is to increase the efficiency of the fan in pulling air through the radiator, losing a bit of shroud has a negligible effect. It does lead to the question though: Is the airbox going to be blocking part of the fan airflow itself? If so, I would definitely move the fan to the other side.
With the airbox going in between, I would imagine that even if partially, it is blocking the fan a little.
I never thought about moving the fan to the other side. Would that not affect the performance of the car?
Would you be able to point me in the the right direction for wire extensions? I don’t have soldering irons or anything like that in my garage, or even the materials to spare. So I’d have to purchase
Im in the states so I am not sure what wire harness differences there are. On my car the fan harness extends from the left side(passenger side for you, driver side here). Assuming your wire harness also extends from that side all you really need is 2 feet of each wire(usually 2 wires per fan) and 4 wire crimps as well as a pair of wire crimpers. Generally you can find a wiring kit that contains all of that for around £20.00. You cut the wires somewhere easy to work with. Strip back about 10mm of wire from the old wire(chasis side) and one end of the new wire….slide the crimp over and use the crimpers to crimp them together. You now have a wire 2 feet longer than it used to be. Repeat the process on the other end to reattach your wire to the other cut end of the original(fan side) and crimp that end too. Repeat the process for the 2nd wire and you are done. There are cleaner ways to do it…I use some heat shrink solder tubes that you just slide over wire ends twisted together and hit with a heat gun…the heat gun heats a solder ring built into the tubes which flows over the twisted wires…but regular old wire crimps work fine. I do recommend using heat shrink over the finished joint (it can be shrunk with a lighter or some matches)just because its good practice and helps keep moisture out but its not required. Just be sure that the wire you use to extend is rated for the same amperage as the fan fuse. The radiator doesn’t care what side the fan is on…it will cool the same.
You can’t just swap the fan to the other side of the radiator. The mounting points differ between the normal cooling fan and the extra fan used for air conditioning.
The other option I suppose then is to use the AC fan instead and wire it to the main fan loom. Assuming its the same spec as the main fan…which it probably is since its cheaper to use the same fan twice. I can take a look at mine tomorrow and see if the AC fan looks to be the same part….and measure the mounting points.
Doesn’t sound like I’ll have much luck then.
At a glance it looks like my radiator would fit it, but I’m not so sure now.
Looks like it’s a Dremel job or this twin fan system I was considering before I bought the JR intake. Easiest way to make that decision is to find out if that would be overall thinner than the stock cowling, or if modification is inevitable.
As you can tell, I’m trying not to modify if I can help it. I’m just not mega confident with that type of bodge work yet.
If anybody has a twin fan system, specifically the one from SkidNation (Mishimoto is a bit spendy although I would love to), would they be able to say if it’s overall thinner than stock?
Never thought if be worrying and ducking around a problem created by a few mm. But here we are 
You could always revert to the OEM radiator - they’re quite a bit thinner than the aluminium “upgrades”.
(And more efficient than generic aluminium replacements if Flyin’ Miata testing is to be believed.)
I dint measure the bottom bosses, but top boss measurement shows to be the same:
Physically I am pretty confident it will fit. No sense in speculation though…just unbolt it and try.
My fans at least seem to be different from side to side…but who knows whether they are stock, previous owner modified the car enough
I bought the aluminium radiator to replace my stock one as it had gone green.
It was black Friday, so I managed to get the Ali rad for £20 cheaper than a stock one from MX5Parts
They seem to be identical I agree. I suppose could just try it like you say, though I would have the issue over wire harness length there.
Without a solder or anything like that I could potentially be spending the same amount of money than it would to buy a Dremel or the SkidNation twin system (and hope it’s thinner)
This car man. Love her to bits, but shes higher maintenance than the actual lady in my life. I can’t afford both, one must go
I hate dremel tools honestly. They rarely have the torque needed to get the job done. Most often you just break the little cutting disks before you get anywhere. I don’t know how big a cut you need to make but I would recommend an angle grinder or a body saw(its like a mini-sawzall) over a dremel tool any day. The only thing Dremel tools come in useful for is if you swap often between their small accessory bits. Besides, if the box is going to block fan airflow, you are better off moving the fan so it doesn’t(assuming it fits)
