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Ouch. But it probably relates to replacement wrap around bumpers on modern cars so not toooo bad

About 38% more than buying them from Kinetic, not considering freight.

Steve,

Have you made any further progress on your design?

John

Regrettably no. Work and family have taken priority, and I got side-tracked a little putting a new engine in a friend's daily driver. Did you get my e-mail about the CAD files?

No, I checked my email. Maybe its in the trash, let me check.

Wow this is too cool somebody building something really close to a real caterham. I've seen a few others, but none have had this level of sharing. Perhaps by the time I finish my master's degree (a year and a half or so) I can really start to play with this and follow in your foot steps. It looks great though keep up the great work and keep us updated.

-Greg

I have essentially been traveling for work for the last two months straight and haven't had time to spend in the garage, but I was able to sneak a visit to the Caterham Midlands dealership into my itinerary!

They had an R500 and the prototype Team Lotus Special Edition 7 on the floor as well as several very nice S3 and SV's. That's me with the sh*t eatin' grin in the R500. Unfortunately I didn't have the time to take one for a spin, but it was still a great dose of motivation to get back into the 7 project!

I have been pondering recently on how to design the lower front wishbones around the rather cumbersome mounting arrangement of the stock Miata ball joints.

Ideally, I would like to replace the Miata ball joints with readily available press-in type ball joints. Unfortunately, I haven't been able to come across a loaded type ball joint with the same stud taper and diameter that wasn't originally used in a 1960's muscle car and is the size of my fist! Also, I don't want to re-ream the Miata uprights if I don't have to. So instead I have started looking at if I can replicate the design of the Caterham lower wishbones which use a spherical bearing specifically designed for racing suspensions and proven in day-to-day use in Sevens for decades.

A few minutes of Googling and I found the manufacturer and part number of the spherical bearing. It is a New Hampshire Ball Bearing (NHBB) model ABWT10. At about $40 each they are comparable in cost to a reputable brand Miata lower ball joint. So far, so good.

A bit of layout time in CAD, a bit of rendering time and voilà!


I haven't been able to find commercially available bearing housings and taper studs yet. It looks like the bearing housings will have to be custom machined. For the taper studs, the ones used on early model Mustang bump steer kits look promising. Mazda used the same 1-1/2" per foot taper as Ford. When I get a chance I am going to see if a Mustang outer tie rod end fits in the Miata upright.

Keeping my fingers crossed....

Chassis Shop and some other circle track suppliers offer spherical bearing housings for a -8 or larger bearing. Might be worth checking them out if you don't want to do anything custom.

I would also keep an eye on the deflection angle. NHBB's website says that bearing has 12 degrees of deflection. Based on the experiences with my car this number sounds like it might be a little low* - I'd just keep an eye on it so you don't find out when its too late.

*my car also deviates from the book; actual results may vary

Thanks Andrew for suggesting Chassis Shop. They offer Aurora Bearing Company's COM series of bearings. The size 10 COM bearing only has about 40% of the NHBB ABWT10's ultimate static radial load rating and is limited to 8.5 degrees of misalignment. The larger sizes aren't much better. The Uni-Ball Weld Cup would have been perfect.... At least I can blatantly copy its dimensions and I have a snap ring selected!

Those are '94 spindles? I'm trying to figure out what the difference is between earlier (94-97) spindles and later ones. Any thoughts?

Nice looking work!

They are '94-'97 NA's. Basically the same as '89-'93 NA's. '99+ NB's have the tie rod attachments raised 7.1mm. There are other differences between the NA and NB front suspensions, but those are in the control arms, not the spindles.

Awesome. Thanks. That's just what I needed to know! Oh, and you have a PM.

Well, I am a bit closer to finding commercially available components to replace the Miata LBJ with a spherical bearing.

Light Racing out of Longmont, Colorado sells the correct size weld cup for the NHBB ABWT10 bearing complete with a snap ring for just $16.15 each. The only problem is that they are just 0.84" tall which might not be enough to accomodate the angle at which it will be welded to the control arm tubes. Maybe some nice flat streamline tubing will solve that challenge.

http://www.lightracing.com/products/57-spherical-bearing-receivers

I have also discovered that the dimensions of the Miata lower ball joint's tapered stud are about the same as that of an '87-'96 Ford F150 pick-up truck's outer tie rod end. Who woulda thunk it?

Steve there are press in ball joints that fit the Mazda taper. One that I do know that fits is the ones used in the Nissan Silvia (200sx) as I have some here, just not sure if you can buy them seperate from the arms, but they are easy enough to press out. The other I am told is from a Ford, just not sure which model but could find out if you would really like to know. Your design looks great, nice and clean. I did consider using the Nissan ball joints but in the end opted for the originals, as they gave me more ability to lower the arm in relation to the b/j centres so that I could clear the tie rod. I will have them finished soon I hope so will have something to show you.
Bruce