Honda S600 – Suspension

Honda S600 Motorcycle Suspension

Motorcycle engine, motorcycle suspension.

Miata Parts

The original plan for the suspension was simple: Buy a Mazda Miata with a blown engine, take out front and rear subframes, narrow subframes as needed, weld subframes to Honda S600 frame.

This would have worked out reasonably well if not for the fact that the S600 is SO MUCH NARROWER than the Miata.

Miata Subframes
Miata Rear Subframe Narrowing

With the rear subframe narrowed the appropriate amount, the diff wouldn’t even fit. This lead to plan b: use the A-arms, but ditch the subframes.

Rear Subframe

This approach required a new rear subframe to be designed and built to accept the Mazda suspension arms. Fortunately, the lower control arms were so close together that they could just use a common tube on the bottom. There wasn’t a lot of accurate jigging for this; I 3D scanned the frame (that’s why there’s white powder on the frame in the images), drew the new subframe in CAD, and then cut the tubes as closely to the CAD as I could and hope that was enough to self-jig. It worked pretty well.

Rear Subframe Build 1 Rear Subframe Build 1 Rear Subframe Build 5 Rear Subframe Build 4

There were a few months between beginning this project and finishing it, and it got a little rusty in the interim.

Front Suspension

Unfortunately, the A-Arms on the Mazda were too long to use in the front, so I had to use custom arms that attached roughly to the stock pickup points on the vehicle side and to the Mazda upright on the wheel side.

car motorcycle suspension Car motorcycle suspensio 2Both front and rear use Yamaha motorcycle shocks. The first thing people do when they get a new fancy literbike is to swap out the exhaust and rear shock. This means there are a ton of pretty decent coil over shocks on eBay right now for a fraction of what they’re worth.

Finishing Touches

Frame before powder
RC51 for scale. I miss that bike.

After everything was located and welded onto the frame, I took it all apart and had the frame powder coated. I was going to sand it and paint it myself, but I remembered that I hate both sanding and painting.

powdercoat frame

S600 RC2
S600 RC1DIY car alignmentAlignment was done with this super expensive rig that consists of a 2×4, a creeper a big zip tie and two tape measures.

More about the S600:
Honda S600 – Acquisition and Deconstruction
Honda S600 – Drivetrain

Honda S600 Motorcycle Suspension


    1. The whole car? Man, I don’t know, maybe a thousand? I did it slowly over the course of 4 years.

    1. I’m using about 4:1. I chose my ratio based on the fact that I’m not super comfortable with the idea of going faster than about 115 in a car that small 🙂

  1. Thank you for your reply, would you be able to replicate the front end suspension setup? I would buy it from you, my S600 has a S800 chassis which has front disc brakes and live axle rear diff.

  2. Could you send cad info or any dimensional data for what you did front and rear. I would like to replicate as much of what you did with the suspension as possible. Parts list etc…even if I have to get it made.
    I just bought a coupe that was supposed to come with running gear from a mazda but all I have is an S800 chassis with adjustable upper arms and an empty RX7 axle housing with a 4 link…so it is going to cost as much to chase and replace to sort it out or do what you did; which is a better layout anyway and would save me alot in stuffing about trying to get dimensions right.
    I also have a roadster with an S2000 engine/gb which the engine fit (pan is 20mm from the road, Jag rear with issues, exhaust still a mess)…still a work in progress. Lots of stuffing about with that to and thinking I should copy your rear layout for that.
    Cheers, Dave

  3. what tires your running on compound and size? also how light could you make the s600 to where it would do less stress on the trans, or could you get away with running a trans cooler to help.

    1. I’m running the Toyo R888s. 225/50-14 in the rear and 185/60-13 in the front. I’m at about 1300 pounds now but you’d be hard pressed to get it significantly lighter unless you start swapping out body panels with carbon. The transmission seems fine so far; it uses the engine oil so as long as you keep the engine cool you keep the trans cool; that’s part of the reason I’m using a radiator that is “too big”.

  4. Hi Matt,
    How much NOS can these engines take? I will be using a Honda Blackbird 1100cc engine on my build, do you think the factory front suspension geometry setup is good enough? I have 238mm ventilated rotors with Wilwood 4pot brakes, my car is a S600 coupe but has the S800 chassis with disc brake front and live axle rear end, so I will probably get a Toyota diff and shorten it to suit, I would like to know what you think about the front supsension setup if we are chasing around 130mph speed.

    1. You can probably safely hit the engine with 35 horsepower repeatedly, but that’s really just an educated guess. I’m running 35 and haven’t had any issues, but I’ve probably only used it 25 times. I personally wouldn’t trust the factory suspension, especially if you’re planning on stickier tires and big brakes; that braking load is going to be way more than the car was ever designed for

  5. Hi matt do you still have the cad file for the mx5 pick up points as that would save me a lot of time with my project.

    1. I don’t, but I got the pick up points somewhere on the internet and then drew them into CAD, so you can probably still find the dimensions online if you do some searching.

  6. Hi Matt,
    Amazing build. So impressed and inspired. Its time to convert my 1969 Triumph Spitfire MK3 to bike power. The weights and structure seem all quite similar to the s600.
    I am considering a Yamaha R1 engine and trans for my build. After going through this process, do you see an advantage in purchasing a running bike as a donor in order to get all the matching and functioning sensors, relays and electrical….In some cases I am finding some at decent cheap examples. You do see some example “complete” packages on eBay too with harness.. But most are missing some key items. Probably stuff that got damaged in the crash that led to their salvage.
    I have only built early, pre-high tech, cars and motorcycles. Not yet knowing how hard it is to deal with tech compatibility, trouble shooting and managing electrical issues and even some interdependent mechanical systems… it seems like it might be worth an extra 1000 bucks or so to begin with a runner?


  7. Hi Matt was planning my next project car …triumph gt6 but this really grabbed my attention. Question I have is the availability of s600 project cars. Dont want to cut up running car. Second is motor. I’m looking at honda k20ish with 200 to 300 hp range. Is this even doable? Or too much motor. Under 2 litres is ok too. Thought of big bore destroke 10k rpm vtec sounds fun to me. Coupled with 5 speed. My wife ok’d a fairly large 25k budget…. I would be doing 80% of work…. can I get it built for that…the triumph looks over budget that’s why this is so attractive.

    1. I ran across a build thread a while back of someone putting a 1st gen S2000 engine in one and I seriously considered that; though you’d still have to re-do the entire drivetrain because the rear chain drive setup on the S600 is made for less than 50hp. Even with the Triumph you’d be swapping out the rear end, driveshafts, hubs, etc to something bigger, so I suspect the cost would be the same. Could probably be under 25k if you do most of the work and are frugal.

  8. Hi Matt! You inspired me years ago to start an S600 build and finally I have using a CBR1100xx. Just curious as to what brake/clutch master cyl. You used?

    1. Brake MC is from a Mazda Miata. I built a bracket and modified the brake lever to fit it. Clutch MC is from the motorcycle. I originally used a Miata MC, but the bore is too big and it wasn’t a good feel. It was like a switch.

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