AR-1 long term review

Magpie · Postby **Magpie** » Sun Apr 30, 2017 10:06 am

Started them cold 26 and they went FL 32.4 FR 31.6 RL 33.7 RR 31.1

Lap times were 1:04.4440, 1:03.6285, 1:02.7184, 1:01.9994 (excludes in out lap). My previous PB was 1:00.47 so almost flat out on the last lap. They did feel a little 'squirmy' on the last lap, however this was more than likely due to incorrect pressures. Session 2 times with the AD08R's were 1:03.1237 1:02.7764 1:02.7777 1:02.3219.

Based on the temps (C), will set the fronts at 28 and the rears at 29 targeting 33/34 hot. Camber is approx -3.9°F and -3.5°R again very similar to what I run the AD08R's (33.5 psi hot). Not what I expected for a R Spec.
FL 47.2 52.2 60.5 (53.9 more pressure required)
FR 62.8 51.7 40.0 (51.4 almost spot on)
RL 57.2 57.2 59.4 (58.3 more pressure required, however temps seem strange)
RR 61.7 51.7 44.4 (53.1 more pressure required)

The quick glance at the surface tyre temps whilst on the track showed them getting to about 79°c when loaded up, but cooling down to about 60 on the straights. I do not log this data...

The AR-1's were taken off and then the AD08R's put on, so looking at the G Plots for session 1 and 2 should be a 'reasonable' comparison as conditions were similar. Note I did manage to do 1:00.4391 on the AD08R's much later in the day...

The AD08R's are showing better in braking, however was also taking it easy on the AR-1's so as to not flat spot them on the first outing. The blue circle (1.2g) shows that on the AD08R's the driver is making better use of turning/braking, but the AR-1's even on a heat cycle have just as much 'grip' as the well used AD08R's.

AR-1 by Eipeip, on Flickr

Will follow up with more data after the MX5 track day on 15/05/17.

Todd77 · Postby **Todd77** » Sun Apr 30, 2017 8:28 pm

Good review mate! I'm actually looking at these for when I do the nulon events. My cousin runs them and think they are great!

Magpie · Postby **Magpie** » Tue May 16, 2017 8:26 am

Ran the AR-1's at Lakeside on 14/05 and QR on 15/05,
Alignment settings (done a few months ago)
LF -3.9° camber, 2.5° caster, +1.4mm toe
RF -3.6° camber, 2.4° caster, +1.4mm toe
LR -2.5° camber. -1.5mm toe
RR -2.6° camber, -1.5mm toe

Tyre pressure/temps were taken with http://www.longacreracing.com/products.aspx?itemid=1721&prodid=11677&pagetitle=Temperature+Compensated+Digital+Tire+Pressure+Gauge

Comments:

Lakeside started cold with 27/28 and they went around 35/36 hot. The pressures were not adjusted, it was about seat time at Lakeside than 'pushing' the tyres. Managed a 1:04.2287, previous PB was 1:04.3209 (Feb 2017 on AD08R's).
QR started 28/29 cold, the tyres were adjusted mainly on the left hand side based on tyre temperatures. About 2 psi was let out of the LH side over the course of the afternoon.
Will take the tyre pressures this afternoon as they should have cooled down enough, plus the car is back in the shed. These will be my starting pressures for QR next time.
Managed to set PB's on the Sprint, Clubman and National. Biggest gain was on the clubman, a 1:03.8752 down from 1:04.4096 (Jap Nats 2017)
Tyres are very sensitive to PSI changes. Very easy to 'feel' when they exceeded their 'best' hot PSI. The tyres were still predictable and did not let go at all, BUT needed a lot of steering wheel inputs to keep pointed in the right direction.
Tyres are sensitive to alignment. Plan to set front to -3.0° (recommended maximum by Nankang) at both the front and rear, toe will remain unchanged.
Pressure gain was surprising as was the 'best' hot pressure. Next track day at QR I will drop them to 29 hot just to see what they are like.
For me the rears were always hotter than the fronts, this suggests that the car is understeering more (and it was), so a look at spring rates maybe in order.
Managed to fill the area of the tyre G Plot better than on the AD08R's.
Longevity? Too early to tell.
Theoretical fastest lap on the Sprint was 58.877 - actual 60.3552
Theoretical fastest lap on the Clubman was 63.630 - actual 63.8752
For me faster than the AD08R's and with some suspension fine tuning will be even faster. However, so could the AD08R's...
Will be writing some custom pages for the Racepak software to include alignment settings and notes.

Now the details (bigger images available, just click on the link). Pressures in PSI, temperatures in F
Session 1 (Clubman)

Clubman_S1 by Eipeip, on Flickr

LF

S1_LF by Eipeip, on Flickr

RF

S1_RF by Eipeip, on Flickr

LR

S1_LR by Eipeip, on Flickr

RR

S1_RR by Eipeip, on Flickr

Session 2 (Clubman)

Clubman_S2 by Eipeip, on Flickr

RF

S2_RF by Eipeip, on Flickr

RR

S2_RR by Eipeip, on Flickr

Session 3 (Clubman)

Clubman_S3~ by Eipeip, on Flickr

RF

S3_RF by Eipeip, on Flickr

RR

S3_RR by Eipeip, on Flickr

Session 4 (Sprint)

Sprint_S1 by Eipeip, on Flickr

RF

S4_RF by Eipeip, on Flickr

RR

S4-RR by Eipeip, on Flickr

Session 5 (Sprint)

Sprint_S2 by Eipeip, on Flickr

RF

S5_RF by Eipeip, on Flickr

RR

S5_RR by Eipeip, on Flickr

Session 6 (Sprint)

Sprint_S3~ by Eipeip, on Flickr

LF

S6_RF by Eipeip, on Flickr

RR

S6_RR by Eipeip, on Flickr

rascal · Postby **rascal** » Tue May 16, 2017 9:51 am

Magpie wrote:Ran the AR-1's at Lakeside on 14/05 and QR on 15/05,
[*]For me the rears were always hotter than the fronts, this suggests that the car is understeering more (and it was), so a look at spring rates maybe in order.

Hotter rears would mean the car is oversteering more, not understeering!
Sliding more generally heats up a tyre more than gripping.

Magpie · Postby **Magpie** » Tue May 16, 2017 10:24 am

Rascal - yes you are right. Higher rear average than the front is oversteer, yet the car felt more prone to understeer.

Maybe I should have used google

https://nasaspeed.news/tech/wheels-tires/tuning-tires-tracking-tire-temperatures-and-tuning-your-setup-accordingly-can-pay-dividends-on-the-racetrack/

Magpie · Postby **Magpie** » Wed May 17, 2017 6:59 am

Another error in my post the Toe values have the incorrect signs

Front is -1.4mm and the rear is +1.5mm each side for toe.

Magpie · Postby **Magpie** » Fri May 19, 2017 8:51 pm

Have tweaked the Racepak page for tyre data and added some additional fields as well as 'green/red' lights for camber. The only issue could be that on the cool down laps the tyres are not being 'worked' hence the inside edges are 'hotter' than what they really are.

Also added a comments field to make notes for changes etc.

AR-1 TEST by Eipeip, on Flickr

Magpie · Postby **Magpie** » Thu May 25, 2017 4:39 pm

Alignment done and in light of this it is now obvious why the rears were hotter than the fronts. It is always a pleasure to speak to Ken at Accurate Suspension Services, he has so much knowledge on alignments!

The alignment was, Toe/Camber
FR +2.5mm -4.11°
FL +2.0mm -4.49°
RR -0.5mm -2.94°
RL +10.2mm -3.10°

YES +10.2mm toe on the RL as well as + toe on the front. This was more than likely caused by an off I had at Lakeside a few weeks ago.

The Alignment is now, this is Ken's suggestion for running 205/50/15 AD08R's on 8" rims. On 01/06/17 will find out!

Toe/Camber
FR -0.7mm -3.53°
FL -0.7mm -3.45°
RR +0.7mm -2.91°
RL +0.9mm -2.92°

Magpie · Postby **Magpie** » Fri Jun 02, 2017 6:19 pm

Another 36 odd laps (3 x 6 lap sessions Sprint and clubman) PM 01/06/17 (Time Attack Round 2)

Managed to get under the 60 seconds on the sprint, however I'm still getting the rears hotter than the fronts and hence a fair bit of oversteer (mid/exit corners). Alignment felt much better and was able to do some consistent fast laps. Only did data for the Sprint.

Session 1 - started cold 29 maybe a bit much...

20170601 S1 Sprint by Eipeip, on Flickr

Session 2

20170601 S2 Sprint by Eipeip, on Flickr

Session 3

20170601 S3 Sprint (PB) by Eipeip, on Flickr

StillIC · Postby **StillIC** » Fri Jun 02, 2017 8:19 pm

Magpie wrote:however I'm still getting the rears hotter than the fronts and hence a fair bit of oversteer (

I think you mean you are getting a fair bit of oversteer hence heating your rears up more than your fronts. That is, unless you are overheating your rears, but they look pretty good to me.

When the tyres are cold is the car handling neutral or oversteery?

Magpie · Postby **Magpie** » Fri Jun 02, 2017 8:53 pm

Some of the oversteer would be driver caused, power down too early on exit. However some is on a fast change in direction, like the dipper on the Sprint at QR.

Cold, after warm up lap they are neutral, provided I have the start pressures right. I should have the start pressures right next time out. If I get the tyres too hot a cool down lap will bring them down enough to then do a hot lap.

Having spent almost the past 2 years on AD08R's exclusively, not to mention actually getting faster is a whole new learning curve for me.

Magpie · Postby **Magpie** » Sun Jun 04, 2017 2:19 pm

Again, a rookie mistake... I should have made sure of the car's baseline BEFORE doing any testing

With the intention of making some changes to the car today, set the car up to be weighted and height check...

Turns out that the car has changed from its previous recorded setup. The car has gained 20 kgs (excluding driver). This would be mainly due to the 6.5" rims with AR-1's and the surge tank. The last time the car was weighted was with the 6UL's.

With the AR-1's on 6.5" rims mounted the setup that saw PB's at QR had a 53% cross weight, which is not really a good thing as QR is mainly right hand turns (as is Lakeside), however Eastern Creek has more lefts

As previously mentioned the car exhibited mid/exit oversteer, more than likely this is driver induced and NOT a setup issue. The driver is getting faster hence pushing more hence starting to find limits, this is good.

What was interesting was the rake, with no driver weight the Right side had zero and the Left -5mm. This should have made the car more understeering. Have set the car up with +10mm of rake by raising the rear, whilst this may increase the oversteer it sets a known baseline to test from. The cross balance is now 51.47%

Also checked the Cold pressures in the tyres (last hot pressure)
LF 27.5 (36.4)
RF 29.6 (36.1)
LR 25.8 (36.9)
RR 29.5 (35.9)

project.r.racing · Postby **project.r.racing** » Tue Jun 13, 2017 8:41 am

It is interesting seeing the differences in pressures. You can tell by the changes the left hand side is doing all the work at Lakeside.

Magpie · Postby **Magpie** » Thu Jun 22, 2017 7:23 am

At the recent MX5 Club track day at Norwell Motorplex I took the opportunity to run a set of 2015 AD08R's on the Advanti Racing 8" rims as well as the AR-1's on 6.5' rims.

In a nut shell the AR-1's were 01:07.538 and the AD08R's were 01:08.637.

However, was it a 'fair' test?

The AD08R's were old and well used on the track between Oct 2015 and Oct 2016, then they have been stored (correctly)
Jumping straight from the almost 3kg heavier 6.5" rims required a change in driving style. That is inputs had to be VERY smooth, this is something that I found it difficult to adjust to over the first few sessions.
It took time to find the 'sweet' spot for the AD08R pressures.
The AR-1's on 6.5" rims felt like putting on your favorite jumper, warm and familiar. A reflection on the amount of time I have spent with them
The AR-1's only required a few pressure tweaks again on the LH side, just like the AD08R's
The AR-1's had on average about 5°c more internal temperature and 1.5 psi more than the AD08R's

Interestingly at Norwell I was not 'cooking' the rear tyres like I did in the past, but like QR and Lakeside I'm still not making full use of the tyres grip when braking heavy. However, I am managing to 'fill the circle' by trail braking more and this is a positive.

Another interesting observation is that on average I set my best times on the second hot lap of a session.

Could have done another session, however was stuffed, plus I had 'peaked'. Did around 45 laps for the day so even dropping the last session it was very good value for money.

Session 1 - AD08R's on 8"
Started at about 0900. Had a big lockup on the first hot lap due to brake bias adjustment. Did not get much heat into the tyres. Initial feel was VERY light steering, hence very easy on the inputs (steering, brakes, acceleration)
Fastest lap (#2 of 6 ) 01:11.647

S1_AD08R by Eipeip, on Flickr

Session 2 - AD08R's on 8"
Started at 0954. Again very light on the inputs. Adjusted left pressures up to 34 psi, right side left alone as temps indicated psi about right.
Fastest lap (#4 of ) 01:09.973

S2_AD08R by Eipeip, on Flickr

Session 3 - AD08R's on 8"
Started at 1039. Again very light on the inputs. Adjusted left pressures up to 35 psi, right side left alone as temps indicated psi about right.
Fastest lap (#4 of 4) 01:10.126

S3_AD08R by Eipeip, on Flickr

Session 4 - AD08R's on 8"
Started at 1126. Again very light on the inputs.
No adjustments to pressures. RH side bump +3 clicks (to hard) .
Fastest lap (#5 of 6) 01:08.637

S4_AD08R by Eipeip, on Flickr

Session 5 - AR-1's on 6.5"
Started at 1249. Felt 'normal' for any input. No adjustments to pressures.
Fastest lap (#4 of 6) 01:08.471

S5_AR-1 by Eipeip, on Flickr

Session 6 - AR-1's on 6.5"
Started at 1334. Felt 'normal' for any input. LH pressure increased to 35 psi.
Fastest lap (#2 of 5) 01:07.982

S6_AR-1 by Eipeip, on Flickr

Session 7 - AR-1's on 6.5"
Started 1416. LH side pressures increased to 35
Fastest lap (#3 of 5) 01:07.538

S7_AR-1 by Eipeip, on Flickr

Session 8 - AR-1's on 6.5"
Started 1504. No tyre data, loaded car after session finished.
Fastest lap (#2 of 4) 01:09.060

S8_AR-1 by Eipeip, on Flickr