Are Coilovers Universal?
If you are looking to buy a set of coilovers, you may be asking whether coilovers are universal and fit all cars.
The short answer is it depends on the coilovers. If you are looking at a complete coilover kit, then no, they are made to be car specific and will only fit the model of car(s) they were designed for. However, if you are looking at a universal coilover sleeve and spring set, then yes, those are universal and will fit any car that has shocks which match the inner diameter of the sleeve (so that you can slide the sleeve onto the shock). Coilover springs themselves, generally come in standard sizes and are universal, as long as they are the correct inner diameter.
The long answer is a little bit more complex because you have several factors to consider when looking at a universal coilover sleeve and spring kit, however, I will answer those here.
Firstly, What Are Universal Coilover Sleeves And Springs?
Universal coilover sleeves and springs come with a threaded sleeve and adjustment collars, which allow you to replace your factory spring with this spring, and by using the sleeve and adjustable collars you are able to adjust the ride height. They look like this:
They slide onto your factory shock, with the sleeve sitting on the bottom spring perch. When installed, they look like this:
Many cars have wide spring perches on the front, which can make it difficult or impossible to install the sleeves and adjust the collars. In that case, you could cut off the factory spring perch using an angle grinder, and then install the sleeve. Here is an example of that done on a front BMW E28 shock, you can see how just the welded base of the spring perch was left, and the sleeve sits on that:
NOTE: If doing this, be very careful not to cut through the shock housing, and ideally remove the damper as the heat could cause the damper to blow up if it gets hot enough.
What to Look For When Buying Universal Coilover Sleeves
When buying universal coilover sleeves, there are a couple of things you want to look for in order to get ones that will fit your car.
Diameter of the Coilover Sleeves
First and most important is the inner diameter (ID) of the coilover sleeve. You want to measure the outer diameter (OD) of your shocks, and get sleeves that are 1-2mm bigger to ensure that they will be able to slide over your shocks. Make sure you measure the part above the spring perch as that’s where they will be sitting.
If you get sleeves that are too small, they won’t be able to slide on. If you get sleeves that are too big, they won’t sit properly and could be even dangerous to install and use.
Spring Length
You need to consider the length of the spring you are getting and make sure that it will remain captive when the shock is at full extension. If you want to go super low, you will need to get short springs, but then these probably won’t be captive on factory shocks. In this case, you will also need to get helper (also known as keeper) springs:
Helper springs sit either under or on top of the main spring and help to keep it captive when the shock is at full extension. You can see the helper spring here on the photo from earlier:
When compressed under the weight of the car, the keeper springs fully compress and don’t add much to the height of the car – usually around 5cm-10cm (1/4-1/2 inch).
The reason why you’d need helper springs to keep your springs captive is that if the springs are too short, and you go over a bump or the shock extends past the height of the spring for whatever reasons, the springs could unseat themselves and this could have very negative effects to the handling of your car, as well as cause potential damage to your suspension. Basically, it’s not very safe.
Spring Rates
You also need to consider what spring rate you are going to get the springs in. The spring rate plays a big factor in both ride comfort and handling:
Too stiff and you’ll be bouncing all over the road and not have a very good time in the car.
Too soft and you’ll be bottoming out all the time and the car will roll around a lot.
Which spring rate you need is going to be determined by the car and what you intend to use it for. The car’s weight, the dampers, the height you are going to run will all play a factor, so you may need to do some research here to discover what the best combination for your setup is.
Some Things to Consider If You are Looking To Buy a Universal Coilover Sleeve Kit
The biggest thing to keep in mind when looking at universal coilover sleeve kits is the fact that your factory shocks were probably not designed to go as low as you are planning or to handle the high spring rates.
That being the case, unless you are using aftermarket dampers paired with the universal coilover sleeve kit, odds are you are going to blow your factory shocks sooner rather than later.
Now, you are most likely looking at universal coilover sleeve kits because they are cheaper than a full coilover kit. However, you need to keep in mind that you are probably going to have to buy new shocks not too long from now, and you are likely to blow those up too if you continue running the coilover sleeves.
So, while it may look cheaper at the outset, you’ll probably end up spending more money than if you just bought a proper coilover kit.
However, if you are dead-set on getting universal coilover sleeves, you can buy them here:
BUY UNIVERSAL COILOVER SLEEVES
Are Coilover Springs Universal?
Now we’re just talking about the springs that come on coilovers themselves, not the universal sleeve kits mentioned earlier.
Coilover springs generally come in standard sizes and can be swapped over to any other coilover as long as the ID is the same, making them universal.
The benefit of doing this is that if you want a spring with a different spring rate for your coilovers, you can just buy a set of coilover springs with the correct ID and length and swap them on. That’s going to cost you a whole lot less than a new coilover kit.
Eibach is one of the biggest producers of universal coilovers springs that come in a huge range of sizes, IDs and lengths to suit basically any coilover on the market.
If you are looking for universal coilover springs, you can find them here:
BUY UNIVERSAL COILOVER SPRINGS
Cars owned: Mk2 Golf with 1.8T swap, BMW E28 with M30B35 swap, BMW E36 328I Mtech, BMW 750IL, Nissan 300ZX, Honda Civic EF
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