Can someone educate me on why Radical moved away from the Quaife and went to the 6-spd Hewland box? I'm assuming of failure rates, but I haven't read of any instances myself.
Specifically 3.5L motor application.
@99sh Seems like a good "Ask Phil" question. Radical moved between Quaife and Hewland more than once in the SR8, but I don't know about the RXC.
I'm going to revive this thread as I'm sure some have experience 5 years later. It seems the Quaife fails more often in these cars than the Hewland. How robust is the Hewland?
@nautoncall The Quaife Hypoid (QBE72G) and Hewland JFR have nearly identical technical specifications. See this response from Phil Abbott about the history of them in the SR8: Question 4 - "I'm interested in how the SR8 was developed. I've got a couple of them (#42 and #87) and they came with such different equipment! #42 came with an AiM dash and a Quaife QBE58G gearbox, and the #87 came with a Stack dash and a Hewland JFR200 gearbox. Later came the QBE72G gearbox. Can you share any stories or history about how you worked with those different suppliers as the SR8 evolved from 2005 to 2012 (when it all seemed to come together to a single supplier set). Thanks! John (@parsonsj) – Radical Sportscar Registry
I also talked with the Hewland guys about all this, and they told me that the early JFR failures were due to use on a chassis dyno (rolling road to you Europeans) as this kept gear lube from moving around like it would when turning corners.
As for me, I've been using the Hewland for the past several years. It's got a plate-based diff which doesn't get that weird "locked-up" feeling that the Quaife has with its wave-trac diff under heavy braking. Plus Hewland still makes parts and I've found a US-based place to service it (Scott Young Enterprises in Texas). The last refresh was about $6k, which included a new CWP and custom seals to keep the shifter slider from leaking.
I've modified my gearbox cooling to use a fluid-fluid system (similar to the SR8 engine oil cooler). That way, when I'm warming the engine before a session, it's also warming the gearbox. The Hewland also has many threaded bosses suitable for use with mounting the compressor/accumulator, wheel speed sensors, fluid vents, catch cans, etc.
I've also found the Hewland tech support and documentation far superior to Quaife, but maybe that is just me.
In the end, both gearboxes require aggressive maintenance and periodic refreshes to keep them alive. I replace (and inspect) the fluid after every event. I do 6 events a year or so, and I refresh the gearbox in even years, and the engine in odd years.
@parsonsj Thank you so much. I had been talking to someone about their RXC and it had the Quaife and just had 12K worth of work done and the car only had 40-50 hours as I recall. And the motor was the weakest motor, 3.7L V6 Ford NA in the earlier cars.
