Hi, I'm a complete newbie in the kit car or self build car scene. But been in modified cars a while. After some talks with my Dutch friend Bas (also on this forum, mid-engined ideas) I just have to build a Super Seven (even if I've been reading kit car mags for ages and always loved the Ultima's and so). It won't be a real Locost, more a midcost
Because I MUST HAVE age-related plates to re-import an SVA'd car to Belgium, where I live, I must make sure it is a single donor project. BTW: the only way of registering the car is by having it SVA'd in the UK, Belgium otherway prohibites self build cars!
I'm using a Mazda RX7 (1986 model) for donor, mainly because I only want to build a car if it has a rotary engine, and also because I have one for donor.
I took the donor car apart, and will use steering, IRS, wheels, brakes, gearbox, engine... from that one. So nearly everything. There's however a problem with the front hubs. These are from a McPherson type strut. So a ball joint like for the Locost-by-the-book cannot be fitted. The hubs don't have the upper mounting hole. They are mounted by two holes sideways. I'll post a drwaing to explain.
How can I modify this, safely. I was thinking about bolting a selfbuild piece on the strut mountings, that would provide the hole for the top balljoint.
Any comments on that?
I really want to be able to use the donors brakes, as they were made for a capable sports car in the first place and should give real stopping power to a light-weight car as the locost.
They drawing is just to give an idea, it's not very accurate, as I'm not a CAD-CAM specialist or something.
Rescued attachment hubs.jpg

Found another RX7 builder who lists the parts he got from his donor, and parts that had to be sourced elsewhere.
Doesn't quite answer your question, but may be of interest

Click Here

hmm... although intresting, it doesn't really answer my question, yet. Since the build is very well documented, he might aswell cover the front end. So maybe once he's there... Of course he is using an earlier model, so there might be some differences. Mine for example does have IRS. I will sure watch this builders story evolving. Just a pitty he doesn't go Rotary My car will be lighter as the engine is smaller and isn't very heavy. And it'll start with 150-160hp (stock, but with special exhaust) and once SVA'd go for 180-190. So that'll be something like 360-380hp/ton. I'm planning a basic car, no windscreen, no comfort goodies...

Bart, those kind of adapters have been used and made....I know, I made some

You will need something specific of course, but look at mine for ideas...it is a bit different, but similar in some ways.

http://www.desicodesign.com/meerkat/Manufactured%20parts.htm

you will need to scroll down a little.

HTH

Alan B

Thanks Alan, I had actually read through the whole site of your great car before, but it seems I never looked good enough Guess I was to busy with all the other aspects to notice ball joints.

Bart

I know that MK engineering in Langold make an adapter for the sierra macpherson strut. They may be able to help.

have you figured dimensions for the adapter yet. I, too, am using an RX7, and need some guidence on this aspect. Building an adapter like your drawing will allow placing the upper ball joint just about anywhere, thus creating whatever KPI or caster deemed necessary. By careful placement of the upper ball joint, we can virtually duplicate the upright called for in "the book."

any thoughts??

dave

not really... I'm having a real problem with the law overhere, not even accepting my Mazda RX7 (1982) Widebody, because the tires are non-stock (allowed are 185, I have 225)and the lowered suspension. Right now they let me get away with it, but what about next year's MOT?
So if a widened RX7 is illegal here, how the hell am I gonna register a selfbuild car? That's why the project is on hold, first need to be sure the car would be allowed on the streets at all!
But indeed, the drawing means the upper balljoint could be placed in various locations. I'm not to sure if the books parts are ideal, so instead of trying to get as close as possible to those uprights, we might better do some research on that first. It's good to hear I'm not the only one planning a RX7 donor, two people always know more then one
But right now: no, I haven't made any progress, and I think it'll take at least a few months before I start to do so.
Always in for ideas, though, so if any RX7 related problems occur, I'm sure willing to try to help find a solution!

Dave, what car are you using as donor, SA or FC?

I've been talking with Bart alot about this project and originally wanted to do an MR project using an RX7. But I'm going to do a locost first with SA running gear hopefully starting this summer.

I'm choosing the SA because I want to keep things as simple as possible.

For the ones trying to modify the RX7 hubs:
http://mail.softarc.com/~pasdernick/locost/Feb2000.html
Thanks for this link, Bas!

Bart, Bas - that link is certainly encouraging. It appears the upper ball joint is on a line that the strut used to occupy. That should solve the King Pin inclination question, but not necessarily where, vertically, it should be.

Bas - saw a list once that informed me the rx7 I am using is an FC. Don't know what this means, don't know the difference from SA, or others. Don't really know anything about the cars except they have parts I like. Going to use the irs in a de Dion set up. Hope to move the brake discs inboard. Like the front suspension, steering, transmission, wheels, and more. Not planning on using the engine, however. This one is a bum, and costs of replacement are prohibitive.

dave

Well, basicly, these are the RX-7 models:
SA: 1979-85 (with 84-85 also refered to as FB models)
FC: 1986-91
FD: 1992-present
This is important as the cars are very different. The SA still uses live axle setup, for example, where as the FC uses IRS.
Moving the discs inboard seems of no use to me. It will make work only more difficult, and in my opinion there wil hardly be any positive sides to such a modification.
As for engines: power to weight ratio of a rotary engine is great, aswell as power to size, as these engines are very compact. They are not that expensive, if you know where to look. UK should have plenty of offers.

but postage to Wichita, kansas, usa, would be prohibitive

dmott,

if you're USA bound you should have no problem at all to find rotary parts as USA was the main target for rotary production (well 2nd to japan offcourse:-)).

Go to http://www.rx7club.com/forum
You'll find a forum there with plenty of info on the subject and plenty of USA based enthousiasts.

[Edited on 6/4/03 by BasOlij]

quote:

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Originally posted by dmottaway
but postage to Wichita, kansas, usa, would be prohibitive

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biggest fear is that of the unknown. I am fairly confident that I would be able to plant a piston engine and get it running, and running well. Knowing nothing of the rotary means installing the engine and then praying that it works, and if it doesn't, oops.

I will investigate more. Maybe I will run across a local pro that can be available to help.

It would make building the frame easier, having the lump available right now, to make sure everything fits together.

dave

dmott get yourself well aquinted with the rx7 movement in the USA. In many respects the rotary is a much simpler engine then any piston engine but it does have it's troublesome bits. Starting off with a running engine is a must in that respect. There are plenty of people around in the USA who will gladly lend a helping hand keeping rotaries running. Once you start working on these engines you'll fall in love with them quickly:-)

What I think you should do with the RX7 uprights is scrap them. Then just buy a set of cortina or sierra uprights. Or even buy a set of ali 1s from westfield. It would be a lot less hassle than modifying the uprights you have. Yor may have to change the front brakes if you do this.

the last thing I want to do is buy something when I have a suitable part in hand. I think the RX-7 uprights are amazing in their flexibility! a simple fab on the top end results in an upright with KPI to my liking and my choice of front or rear steer. the way the lower ball joint attaches to the upright makes me think that just about any ball joint will work.

why would I toss all this for an upright that is not readily available in the U.S, that would require changing the brakes, also??

am I missing somethin??

dave

Hm, you must realize that the construction of a "adapter" bolted (welded?) to the uprights of the RX7 could become a weak link. There might appear play on that connection, making steering a bit unprecise. I'm not sure, it's just a thought. It'd be VERY important that the whole assambly is strong, very strong.
Maybe a set of custom made uprights, CNC'd to FC specs, but with upper ball joint accepting point would be the sollution, although it'd probable cost a lot to get those done...
Getting Westfield uprights is a logical decission somehow, yet I do not want to throw away the very capable brakes that came with the donor...