Hey guys. I'm a new member of the forum, although I've been lurking for a while as I design my own locost-ish project. Here's a high level overview of what I'm looking to do, to frame my question:
- Single seat, mid-engine configuration
- Steel tube frame
- 1300cc bike engine (likely 'busa or ZX)
- Chain drive
- 700lb target vehicle weight
- SLA/Dual a-arm/wishbone suspension front and rear
- Maximum use of junkyard/standard OEM parts
- Minimum "complex fabrication" (anything beyond tubing work and basic fabrication, e.g. no CNC uprights or custom diff cases)
I've been making good progress on the overall design and have been able to find general solutions for most things, but where I'm hung up is the differential/cv axle/rear upright system. I've decided that I will try to splurge on a Quaife QDF7ZR
http://www.quaifeamerica.com/qdf7zr-0.html differential, likely making it the second most expensive part of the whole car after the engine. The differential is described as using "Escort/Fiesta shafts," and after much back-and-forth with Quaife about what this actually means, I've determined that the output from that diff is 23 splines in a 28mm bore, the same as Ford used on the "IB5" FWD trans. Apparently these axles are plentiful in the UK as they were used on the UK Escorts and Fiestas, but the only US cars that used this "inboard spline" are 2000-2004 Ford Focuses with the 2.0L SPI engine and manual trans (code IB5).
So that's all well and good - I could use the whole Focus front drivetrain as my rear setup. No big deal, just an easy toe-rod connection to the frame. The problems with this are twofold: the Focus used an idiotic 4x108 bolt pattern, ruling out all the nice lightweight wheels available in 4x100. Second, the Focus used a strut front end, making the uprights difficult to adapt to an a-arm setup.
So now I'm stuck. Custom CVs are far, far too expensive (from what I've seen). Quaife sells stub shafts for a "100mm Lobro" joint, but they're another $300 on top of the diff cost, and then I still need some kind of axles. And the Focus hubs are press-on, so I can't just bolt them on a custom or compatible upright. Machining an upright to fit the press on hub isn't an option I'm considering. Ideally I'll run some OEM upright with a 4x100 bolt pattern that is readily adapted to a-arm connection. I'm not that concerned about geometry (KPI etc.) given that it's just the rear.
Since you all have a wealth of knowledge on parts compatibility and out-of-the-box solutions, I'm interested to hear what you have to say. A few general questions leap to mind:
- Is there a viable alternative to the Quaife chain-drive diff?
- Are there other US-market CV axles known to be compatible with the QDF7ZR?
- Can I affordably ship over some junkyard UK axles?
- Can I piece together custom shafts from Focus inner joints and some other outer joint?
- Can I just duct tape a sawed off broom handle between the diff and the hubs and go easy on the throttle?
Any wisdom is appreciated!
Mike