Oversteer on trail brake

93_Clubman · Postby **93_Clubman** » Thu Jun 08, 2017 10:42 am

omx500 wrote:Still have 16mm rear bar due to not finding another but have increased front bar to 25mm, up from 22mm.

Keep a close eye on the front sway bar mounts as some others that have gone to 25mm or so have found mounts detaching from the chassis.

omx500 · Postby **omx500** » Sun Jul 09, 2017 8:34 pm

OK. To all the people who suggested in a more or less direct way that I needed more spring rate....you were 100% correct. To recap, previously I was running 200lb/inch front and 150 lb/inch rears on DMS gold coilover bodies. This did seem a long way off most people were running, so I ordered some 350 lb/inch front and 275 lb/inch rears. Didn't think the physics of it through well and got them in the same length. I had a bit of room to drop the lower spring seat and thought it would be OK. It wasn't. Turns out before the springs go too far down the shock bodies they start to foul on big hard things like driveshafts and upper suspension arms. I put them down as far as I could and it still looked like a 4wd. I should have taken a photo to give you a chance for a laugh at my expense. Drove it round and was surprised that it was no that hard, so when I ordered 50mm shorter springs I went a touch harder again to 400 lb/inch front and 300 lb/inch. I did a short course hillclimb today and the car feels so much better, with far less moving around, front to rear pitching etc. Was looking forward to putting in a reasonable showing as the track warmed up, but then it seems that the combination of my new OS Giken superlock LSD and my revived A050s have generated too much traction (how can you have too much traction) and clutch started slipping

so went home early again.

I am determined to get a setup which works and keeps working so will just keep plugging away. I feel like I am making progress but it has been an expensive fortnight....

lightyear · Postby **lightyear** » Mon Jul 10, 2017 8:01 am

It's not that complicated to get an MX5 to handle. Buy B.C coilovers with the standard 10 and 8kg springs. Buy a large front sway bar. Wheel align and corner weight it. And a Torsen diff is fine. That's it,there is no need to buy anything else or change bushes.

lucmor444 · Postby **lucmor444** » Mon Jul 10, 2017 10:41 am

Lightyear - slightly off topic but some relevance so I'll ask - any one you recommend for wheel alignment and corner weighting in Melbourne?

lightyear · Postby **lightyear** » Mon Jul 10, 2017 9:49 pm

I only get Nick at Lux racing in Keysborough to do mine. He will be busy, so book it in ASAP.

lucmor444 · Postby **lucmor444** » Mon Jul 10, 2017 9:56 pm

Thx Lightyear

Magpie · Postby **Magpie** » Tue Jul 11, 2017 12:09 pm

lightyear wrote:Buy B.C coilovers with the standard 10 and 8kg springs.

DONE

lightyear wrote:Buy a large front sway bar.

Purchased and then sold it, running OEM

lightyear wrote: Wheel align and corner weight it.

DONE on a regular basis

lightyear wrote: And a Torsen diff is fine.

Had it and then swapped for a two way clutch pack

Other changes:

Had a manual bias adjuster put on the rear brake circuit. This has been replaced with dual masters and custom pedal setup (brake booster delete). The ability to adjust bias on the fly has helped with trail braking.
Notebook to record setup changes (heights, weights, pressures and temps). Cheap and gives amazing results.
Learning the theory (why is it so)
Seat time, seat time, seat time, seat time...

omx500 · Postby **omx500** » Wed Jul 12, 2017 4:48 pm

lightyear wrote:It's not that complicated to get an MX5 to handle. Buy B.C coilovers with the standard 10 and 8kg springs. Buy a large front sway bar. Wheel align and corner weight it. And a Torsen diff is fine. That's it,there is no need to buy anything else or change bushes.

Wheel align and corner weight it. And a Torsen diff is fine. That's it,there is no need to buy anything else or change bushes.[/quote]

Hey mate. Thanks for the tips. I run a fair bit of road course stuff and I am thinking that 10 and 8kg springs would be pretty rugged. It is that compromise issue again!

OT Looking forward to getting my fastback!