Mx5, Chapter 2

[greenMachine]

The 10kg springs have 200mm free length, which is the same as the 6kg that came out.

Given what you are looking at, unless there is an installation issue, 200mm is too long. Logically, that makes sense - stiffer spring, car rides higher with no other changes. And you don't have the adjustment range to eliminate all of that increase in ride height.

Do the math. Those springs are 66% stiffer than what they replaced, so if the originals compressed (say) 50mm under static load, the new ones will compress less than 20mm (unless rising rate). On that example, 170mm free length might be pretty close, given the movement ratio and you want to move the perch up.

Another way of looking at is, how far did you have to move the spring perch? As you have (I gather) not been able to move it far enough, add that in, that will tell you what compressed length is excess, do the calc for how far it compresses under static load, and you can determine free length for that rate spring. Say the numbers are 20mm movement of perch height, you reckon (measure better) another 10mm needed, plus say 20mm static compression, you need a free length of 200mm less (20+10+20) = 150mm (hypothetically) to get your spring perch back to where it was. When you have done this calculation, check that under static load, you have enough spring compression to the compressed (or no) bump stop without coil binding.

Lots of people use helpers. Some don't. If you want to use them, you would need to subtract the compressed height of the helpers from your free length or just move your perch down (or a bit of both). To find out if you need them, how much droop do you have in shock travel from static loaded condition? If that is more than the static compression of the spring, the spring will be loose under full droop condition.

My 2c

[The American]

My 2c

Thank you. With the benefit of hindsight, I could have easily worked out (using your suggestions) that the 200mm 10kg springs wouldn’t work for the target height with these Tein coilovers. I had to lower the perches a lot - all I could. I didn’t measure before I adjusted, but probably 30-40mm, which wasn’t enough.

Tein springs are $300/pair and you’re a little stuck with buying from them, unless you modify the spring seats to accept a more common internal diameter. The set of Tein I have are also fairly cheap coil overs to start with and have 30,000 km on them. I’ve decided not to to start spending money on them for re-valving, more spring sets etc as it would quickly add up to most of a new set of something more suited to the job.

To that end, I picked up a set of MCA’s with 11/7kg springs. They have helpers front and rear, and the front spring itself is 180mm. Alternative spring rates are $50/spring.

I fitted them on Saturday night:



I haven’t adjusted them yet, but out of the box they are sitting at 100mm at the front pinchwelds, and 107mm at the rear. The rake is about right, but about 15mm too low, but with plenty of adjustment room available.

I wasn’t planning on new suspension just now, but I could see that transforming the Teins from a budget street shock into a track oriented set up was going to be expensive without necessarily achieving a good end result.

I’m pretty sure I was running the old springs on the bump stops, and I’ve got some relearning to do with the new set up.

[greenMachine]

Good move! Looks like you were a step or two ahead of me, and I could have saved a whole bunch of electrons

I look forward to driving impressions!

[SKYHI]

Good choice on the MCAs. Which ones did you go for, the Reds?

[The American]

Good choice on the MCAs. Which ones did you go for, the Reds?

They are the ‘Reds’

I will share more once I’ve had a chance to set it up and drive it.

[The American]

The White Mouse is set up and aligned.

Pinchwelds:
115mm front
122mm rear
Camber
4 degrees front
3 degrees rear

The 2012 vintage medium compound semi slicks have gone in the bin, replaced with some new ‘softs’ (this will be the first time I’ve used softs).

The new coilovers with 11/7 spring rates are installed and have had their first drive.

The shiny red expired extinguisher has been replaced by an equally shiny new one.

The White Mouse is looking and driving like a grey rat - a bit scruffier, and with sharper claws.

The next outing is the CQ Crane Hire Goldrush Hillsprint at Mount Morgan, Central Queensland on 14 July.
There are only 76 entries and the driver’s briefing is at 6am - barring any incidents, there should be plenty of attempts at the 2 kilometre course.
According to the start list, there are 9 cars in my class. One of which is a Pace Skeleton, which is a kit car based on the Ariel Atom concept. It is dual entered by the owner, and co-driven/entered by the fellow who usually wins the Noosa Hillclimb in an open-wheeler. There is also a Cobra with a v8 supercar engine (usually top 5 at Noosa Hillclimb), two Silvias, two Skylines and a V8 Cressida.

The Skeleton and the Cobra should have several seconds of daylight on the rest of the field. I will be happy if I can place close to or ahead of the Nissan’s.

[The American]

[The American]

What a weekend!

Scrutineering was taken care of the weekend before at a volunteer workshop in Brisbane, but it was still necessary to be onsite on Friday for documentation, to set up and to hopefully have a look at the track. The drive to Rockhampton took much longer than I expected - 9 hours including stops for fuel and food. At least an hour of this was due to roadworks outside of of Rockhampton. I got to the pits at 2pm on Friday and I was one of the last to arrive.

Late afternoon, there was an opportunity to drive up the course for a brief look. The road winds up the range to the west, and there is an expansive view back to the east towards 'Rocky'. Just driving up it at 40km/h in a 4wd was exciting.

There was some talk of a late start the following day due to dense fog being forecast, and set up had been delayed because one of the semi's carting barriers had crashed requiring recovery. Driver's briefing was set at 6am.

I stayed the night with a local mate who I'd met at the Noosa Hillclimb.

Saturday got off to a slow start with apparently lots of work still being completed to get the event started. The first run got underway about 9am.

I had an embarrassing start to the day when I managed to lose control of my car in the staging area while driving up to the start line.

[The American]

Drivers briefing was nice and early and quite ‘fresh’





The first untimed but ‘race pace’ run got underway about 9am. Cars were released at 30 second intervals and it took very little time to run through the first group of 38 cars, which were then run back down the hill to regroup.




This was my first drive of the White Mouse with the new suspension and tyres, and it drove very nicely. Gone was the uncertain feel of the set up for the last Noosa event. It turns in nicely and feels very controllable once it starts to slide. Confidence inspiring - it feels like I have a lot more room to safely push it than before. Still getting used to not hitting the bump stops. I’m very much looking forward to the next opportunity to drive it (wish I had better words to describe the difference in ‘feel’).

The gentleman talking to me in this shot is Rodger, and he has a nice 10AE.




There weren’t any real incidents on track. The Pace Skelton that ran in my class and just before me in the order, suffered a drastic gearbox oil leak at the top of the hill after the first run. It dropped pretty much its entire oil capacity when a dummy shaft from its 4wd-adapted-to-2wd gearbox slid out of position and off its seal. The owner was able to fix that and get back for some runs. On its last run I watched as it destroyed one of its axles on the start line, and had to be towed for a second time.



The only other incident to occur interrupted the final run of the day and discounted my best time from the competition. Sadly, a spectator had a medical emergency and the track had to be closed to allow emergency services to reach the spectator point.

The location is spectacular, and the elevation change over the 2km course is such that you get to enjoy every bit of the view, with the mountain on your right, and at times, just the sky on your left. I didn’t get to take many photos and my description does not do it justice.





The corners are fantastic, with elevation, camber changes and various combinations of corners that will reward practice. It was not as quick a course - yet - as anticipated. I made it to 4th gear in the stretch away from the finish line, but the rest of the course was 3rd gear, and might have been quicker if I’d used a combination of 2nd and 3rd.


I was in the first group to run, and as a result was lucky enough to get 5 runs in total, three of which counted towards the results. I finished 15th overall (of 76ish), and in 2nd place in class behind the broken Pace Skeleton. My quickest time for the day was 1:40:9 and here it is:



It was a very long drive for a single day event. Thanks to the road works, it was almost quicker to get to Bathurst than Mt Morgan. The organisers are experienced when it comes to Motorsport events, and were able to make some good decisions on the day to address difficulties with spectator transport. Next year, they expect to run the event over two days. As a driver, or spectator, it will be worth the travel.

[Custardtart]

Enjoy reading your write ups and watching the vids. Thanks for sharing

[Kevin07]

If there was a like button I would push it. Thanks for the hillclimb report.

[Magpie]

If there was a like button I would push it. Thanks for the hillclimb report.

AGREED

[Red_Bullet]

Yeah me too, so you drove it 9 hours to Rocky with 4 deg camber?

[The American]

Yeah me too, so you drove it 9 hours to Rocky with 4 deg camber?

I’ve got a little single axle Tilt-a trailer that the Mx-5 goes on (lives on it at home as well). It means I don’t need to worry about getting home if the car gets damaged.

I drove it out to Morgan Park a few years ago, and drove the tyres nearly off it. They were practically slick by the end of the day - and then had to drive home in the rain

The trailer also means I can easily take spares, camping gear, tools, fuel etc.

[The American]

I’m glad someone is reading and getting something out of this thread. As the title suggests, it is the second chapter of my Mx-5 story, and I’m enjoying it, and the places it is taking me.