Learn Me: roll your own coilovers

I think I’m in the market for some coil overs for my X1/9. Factory style struts and springs take up a lot of room and don’t allow for wider wheels and tires, so coil overs are the common solution. Plus corner weighting and ride-height control is a big bonus.

Midwest Bayless sells complete coil overs for the car, ranging from $2200 for single adjustable to $2800 for double adjustable Konis. They also sell just the strut housings for $750. This is what a set of $750 dollar housings look like:

I’ve seen other people make their own, and I think this is the path for me. I’ve got plenty of fabrication ability and resources, but no hands-on knowledge of coilovers.

I’m reasonably confident I could make housings just like the ones Bayless sells for $40 of materials. Maybe $100 if I want to get the flanges cut out on a water jet or laser. I suppose I could make them out of titanium or gold or something if I really wanted to get the price more comparable to Bayless. A tube, some cut flanges, an end cap, and a sleeve ring. Add tig welding and powder coat. Do I then add in these sleeves, springs, and some Koni inserts?

I know Koni inserts aren't cheap- like $650 a pair. All in I'd still be under half the price of the Bayless units.

Should I look at modifying other pre-assembled coilovers like Penske or something similar?

I'd love to know if I'm on the right track, and any pitfalls I should look out for. Please share your homebrew coilover knowledge, or point me to awesome build threads. Thanks!

Substitute your home-grown housing for the Bilstein in this thread and there's some good info

http://www.miataturbo.net/suspension-brakes-drivetrain-49/better-bilstein-ebay-coilover-thread-78451/

I'd say go for it - how hard could it be?

Like I said over on your X-1/9 thread: Make sure the welds for the mounting tabs are well done. You don't want those to break, especially if you're planning on using sticky rubber and heavy spring rates (and who wouldn't after making your own strut tubes).

Also for the X-1/9, you'll want to stiffen the upper strut mounts on the body as they tend to flex and bend when hammered. Obert offered optional stainless steel strut mount "doubler" plates to resolve this issue. I know some have adapted Fox-body Mustang adjustable strut mounts to the cars which would help improve adjustability and reduce the strut mount weaknesses.

Here are the pictures of the ones I received from C. Obert & Co. I think they cost me $600? Don't remember other than it was more than the car was worth and I was stealing pennies from the couch to keep the bank account in the black.

I also welcome the commentary from the great, all-knowing, all-enabling sarcasm that is the GRM Collective(tm).

It has been a long while since I looked into X19 stuff so help me out here.

You have these on your car, correct?

Are you planning on going to rabbit inserts? Do you need to drop the mounting ears? or is that a 128 thing?

Anyway. If you don't need to change the tube just cut the spring perch off the existing tubes with an angle grinder or whatever, smooth it off with a flap disc or belt sander or file. Place the sleeve where you want it. I usually put the strut insert in and tighten the nut down, push the sleeve up and mark the tube where the new perch should be located and turn a stepped perch on the lathe that I then weld in place. That way when you tighten the strut insert in it holds the sleeve as well.

This has been standard practice for as long as I can remember.

I would be looking for 4 front Rabbit strut housings so I could follow this guys foot steps. X1/9 Rabbit Struts

That's the way I've always planned to do when I finally find an Exxie worth buying. I actually had all the stuff needed to do it (4 external thread strut tubes, springs, collars, etc) but Ditchdigger wanted a pair for the Triumph 2000 project, and another buddy wanted a set for his MK3 VW project.

So when I built my own for my Mirage, I used A1 Rabbit tubes in the front and the rear was basically a modified dirt modified setup.

For the front, I filled it with the Koni 2812 inserts for the A1 rabbit since the weights and travel were really close. We cut off the rabbit mounting ears and used the mirage lower mounts. Then we topped them off with a set of Cusco pillowball mounts.

In reply to cmcgregor:

The Fiat uses struts, not shocks, so the Miata information does not apply. Bilstein shocks cannot carry strut side loads.

In order to make a strut from a Bilstein, you have to:

1) hard chrome plate the shock body so it's like a linear bearing guide rod

2) weld a strut mount plate stud to the bottom of the shock body

3) fabricate a strut housing with a couple dry-slide bearings that match the chrome-plated shock body, mounting ears for your knuckle, and a hole on the bottom cap that fits your shock shaft end. you'll also need a spring perch on it, so add a c-clip groove or weld on a perch.

4) the shock, shaft end first, into strut housing with a bit of grease, and tighten a nut to the end of the shock shaft to fasten it

6) install your spring and bolt your strut plate to the top of the strut (which is actually the bottom of the modified shock body).

EDIT (2015-02-11):

Here are some illustrations I made to show how Bilstein shocks and struts go together:

In reply to series8217:

Or order a set of MK1 VW Bilsteins, Part No: V36-0103

They look kind of like this on the left and they are shorter than the stock MK1/A1 Rabbit parts:

The ones on the right are stock length 924/944 struts modified with adjustable spring perches and Koni inserts.

In reply to series8217:

Thanks for that. Obviously I gots some learnin to do....

cmcgregor wrote: Substitute your home-grown housing for the Bilstein in this thread and there's some good info http://www.miataturbo.net/suspension-brakes-drivetrain-49/better-bilstein-ebay-coilover-thread-78451/ I'd say go for it - how hard could it be?

Dammit. That thread just made me buy some eBay coils and isolators. Decided against the torrington bearings since my car's a DD. Now to figure out a suitable spring length.

Thanks for all the great info everyone!

So any tips on selecting the insert length? Should I just make it close to what is in the car now less the amount I plan to reduce the ride height? I expect I can fine tune with spring lengths from there.

Ethnic Food-Wrap Aficionado wrote: I would be looking for 4 front Rabbit strut housings so I could follow this guys foot steps. X1/9 Rabbit Struts

That thread is pretty helpful at one thing: showing me how much easier it would be to just make my own tubes from the ground up. I've got a lathe and all the metal tools one could need, so I think I'd just start with my own flanges and thread my tubes myself. It would save me the trouble of grinding off all the things I don't need, and the disassembly of everything.

I've gotta hand it to the guy for taking on the task without any tools to speak of and making due. Pretty inspirational in many ways.

When I was planning on racing my A1 chassis Mk II Scriocco I looked at making my own struts and using Koni DA inserts. As mentions if you have some fab skills and a welder & lathe it's not hard and I have all three, but I came across a complete set of slightly used Bilstein threaded body racing shocks & struts for a good price so I went with them. These strut tubes use remove able strut inserts by Bilstein. I never checked to see if a Koni insert would fit?