THUNDERHILL RACEWAY PARK NEW TRACK SURFACE EVALUATION

THUNDERHILL RACEWAY PARK NEW TRACK SURFACE EVALUATION

Dave Moss
2007 Triumph Daytona 675

Lap times averaging 2:05 to 2:01

GENERAL:

VISUAL:
Surface color contrast to ground is stark and the consistency of the color demands attention. This is perhaps the most profound visual change when on the track having adapted to muliplte colors and markings. There is an immdeiate visual impression of smoothness just looking at the track, and that places a good state of mind into the rider while looking at the track from the hot pit. The immediate visual impression is one of a European track surface, as per MotoGP camera shots, sans curbing and paint.

QUALITY OF FINISH:
Is reminiscent of 600 grit sandpaper while driving at speed on it. That would apply to overall tire finish (with correct set up and pressure) as tires are polished after riding on the track, much the same as Laguna. Seams are visual but appear to be level and blend in evenly with each other.

CURBING:
There is an odd combination of flat and raised curbs. The raised curbs are a known concern for motorcyclists, as the fast line requires the tires to be within inches of the curbing at apex, and that will cause hard parts to hit the curb (I did it myself yesterday while passing someone in T10).


SPECIFICALLY:

STRAIGHTS:
15-1: there are no discernable bumps or seam issues on this straight until after the building where there is a gate in the fence for track access. When going to the far right to set up for T1, crossing the second seam to set up for a late apex of T1 will upset the bike momentarily when this seam is crossed.

9-10: once T9 has been exited, there is a very smooth drive over the hill and down the straight to T10. I found no high speed bumps at all in this section.

12-14: once through T11, the racing line was very smooth all the way to the braking zone/bridge for T14.


TURNS
1: The old surface gave paople serious angst while approaching at speed knowing that the bumps entering and at the apex of the turn would create a brutal and somewhat violent experience with the bikes suspension. Now approaching the turn in point from a wide right entry to the right of the current white blend line, there is a sharp high speed bump crossing the second seam from the left. Nothing serious and does not upset the bike at lean. There is also a noticeable off camber part of the third row of new surface as you enter the track. Approaching the apex there are only a fraction of the high speed bumps left from the inside curb running the length of the curb. While cresting and post apex, there are several high speed bumps close to the flat outside curb from the 10th slab going forward to 10-12 past the end of the curb. There is nothing severe, but the rider will feel them at irregular intervals until 2/3rds of the distance between T1 and T2 from far right to fading to the left to enter T2. Huge improvement!

2: The old surface had several hard hits to the suspension at the entry point that continued throughout the entire corner, with some severe surface changes in the middle third of the corner. Now entering T2 there are a visual continuous series of small high speed ripples starting about 3' from the inside and going about 5' wide to the right lasting until the mid point of the turn. If a rider takes a double apex approach to the corner the line is smooth throughout the turn with no bumps that were discernable. Huge improvement!

3: This corner was always a survival corner for the rider/racer in just keeping the chassis neutral and riding out the bumps using mostly an inside line or a wide entry line. Now entering T3 if the rider enters on the paint, there will be sporadic and irregular bumps throughout that line all the way to the corner exit at the end of the inside curb. If the rider takes a wide left approach there are less bumps until the line tightens up mid corner.It is visually obvious that there are shining black spots randomly in the track surface throughout the corner and these are the high speed bumps that are depressions in the surface.Overall much better, especially with one camber for the whole turn from edge to edge.

4: The old cut out in the surface of this turn at the apex point caused some front wheel slides/pushes if not on the right line and with the bike more upright. Now any line can be taken and any apex point selected with no significant high speed bumps at all. The reducing of the curb hieght in this corner is very noticeable. Huge improvement!

5: The approach to T5 seems the same and the old bump on the right hand side from the turn in point is still there but not so pronounced. The dangerous part of T5 was the lip just after the crest that frequently caused low sides. That lip has gone and as such the overall transition to the down side is much smoother.However, at the high point it feels as though there is a broom handle laying just under the surface, most significantly at the left hand side of the track at the crest of T5 and it will get both the front and rear wheels airborne at speed. This rounded ridge seems to run the width of the track at this point, but lessens approaching the right third of the track.On the downside of the hill, there are visual small high speed ripples in a narrow band 2 from the right hand edge of the track extending most of the way down the hill but they are gone before the track flattens out. Worthy of note is the removal of the depression at the base of turn 5 making for a much more aggressive approach to T6! Big improvement!

6. The old approach to turn 6 was full of ripples especially close to the inside curb, some severe enough to cause the front tire to lose grip. The new surface is smooth no matter what line you choose and seems to have more of a positive camber to it on both entry and exit. Huge improvement!

7: Many riders lost traction is this corner due to the high speed ripples in the pavement while being close to max lean angles at the apex, often taking bars out of their hands mine were no exception. That made the racing line through this corner extremely narrow and required precision in execution. Now there are some small high speed impacts from crossing the seams, but they are subtle and do not instill fear. Any line can be taken and there seem to be no severe high speed bumps anywhere that I could find. Huge improvement!

8: The concrete patch on entry, the sink hole at the apex of this corner and the odd raised run off area made this corner extremely intimidating and required a calm head and faith being the fastest corner of the track. The new corner seems wider on exit and while that is not strictly true, this creates a little more of a comfort zone for the rider. The smoothness of the surface on entry, at apex and when exiting up the hill inspires a lot more confidence in attacking the corner and again, the rider can choose any line through the corner with confidence.

9. The old surface had a bit of a dip at the apex point which is gone and it seems that the whole grade from the turn in point to the crest is a little smoother and not quite so steep? It certainly seemed a lot harder to loft the front wheel initially post apex, but this may not be the case. The turn in point to apex has some high speed ripples going in, again about 2' off the inside curb for the length of the curb, and these shift out to about a third of the way out from the right maintaining this band of high speed bumps that are very visible. These disappear about 15-20 before the crest and the downside of 9 is perfectly smooth. Big improvement!

10: The old surface was very smooth here, and it is the same now.

11: There were some high speed bumps in the braking zone for this corner but those have gone and braking now is smooth and drama free. Cresting the inside by the curb is a very smooth transition as is exiting the corner.

12/13. There were tar snakes and patches here, making for a somewhat nervous application of the throttle coming through this area of the track, again requiring precision. In the visual approach to the 12/13 combination after cresting T11, acceleration can be done with confidence and authority.There is a great deal of ambiguity in the current layout in regards to correct lines due to the extra run off being (temporarily) available to riders?

14: The approach to this corner provided a plethora of visual references to use for brake markers along with many different surface conditions to deal with while braking approaching the corner. Along with all of this came some fairly severe braking bumps that we had to deal with. These bumps seem for the most part to have gone completely across the width of the track, but more importantly from the far left of the track. Huge improvement!

15: The elimination of the sink hole in this corner was I am sure what everyone was praying for as you had to hold back from getting on the gas after exiting 14. Now you can hold the throttle wide open once through 14 when you learn the line and that gained me 20mph after the start finish tower with a true corrected speed of 145mph on the 675. There is no doubt that this is by far the most improved section of the track as you cannot wait to get through 14 to be on the gas with authority in 15. Magnificent improvement!


CONCLUSION:

Overall -the track surface is visually impressive, resembling a European facility.- the smoothness of the surface immediately relaxes riders.- the track surface inspires confidence to attack the corners not survive them once a rider has had time to get used to the new track with no reference points.- the improvements in profile and leveling bumps is very significant and should not be understated.- the few bumps that exist currently are marginal other than T5.

For motorcycles, this new pavement is not kind to tires at all being so raw, much the same as Laguna was when first repaved. Some tires will not last more than a morning, even when brand new unless they can be turned around and run in the opposite direction. Riders need to be prepared to come with hard compound tires running higher than recommended air pressures due to the increased grip. As with Laguna, this will get worse before it gets better, so sharing this information is critical to ensure a positive experience for the user, no matter what provider they use when visiting Thunderhill.

SIMPLE IMMEDIATE CHANGES:

Raised curbing in 3, 6, 8, 9, 10 to be flattened out or replaced. Adding the two white hash marks as turn in points as per old track in turns 1, 3, 5, 6, 8, 10, 11.

feedback from Reno Fernley Raceway

Email:

Dave,

Just wanted to say thank you again for working with me and setting my bike up. The bike finally handles awesome. After you left Sunday I added two more clicks of compression on the shock and the bike just handled incredible! It completely took that bounce out of the rear when coming out of the apex of the corner on the gas!

I still feel like I am working too hard to get the bike to lean over all the way though. Also, on my front tire there is appx 5/8” of stripes on the sides still not being used ( obviously because I can’t get it to lean as much as I want to). On my back tire, the whole tire is being used and has a great wear pattern ( you dialed that in PERFECT)!

Would you recommend to do:
Lowering the forks a couple of mm’s to make it lean more?
Take a small amount of preload out of the forks?
Raise the rear ride height?

I am looking forward to doing another track day where you are there so I can use your services again!
Sincerely Thanks again for all your expertise, you are the man!


REPLY:

Hi Mike,
Thanks for the kind words. Glad the bike worked well after the changes and thumbs up to you for adding the compression - nice work!

The front tire from edge to edge has much more profile than the rear tire does and is much more u-shaped. It is very common not to use the front tire edge to edge - the only way to do it is to low side....... we don't want that. SO, don't get caught up in the unused strips being there :)
If you want to make changes to the front, you need to be systematic in the approach. Here are your options.

1. Lower the fork 2mm in the triple clamps and see how that works.
2. Take out fork preload one turn at a time to assess changes in turn in.
3. Take out 3 clicks of compression at a time to assess turn in.

If you have any other questions, please let me know!
cheers,
dave