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19" wheels and slicks on an 812?

Discussion in 'FF/Lusso/F12/812S' started by Frank_C, Nov 7, 2019.

  1. Frank_C

    Frank_C Formula 3
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    While I wait on my 812, got to thinkin.....I signed up for Daytona in January. Maybe it'll be here on time for that event, if not it'll be the swan song for my F12.

    I don't street my 991.1 GT3 RS any more now that I've bought a trailer. Slowly turning it into a track car. Besides exhaust/cage stuff, one of the suggestions from track guys has been to go to slicks and 19" wheels. The main benefit is not necessarily the grip from the slicks, but a huge down force increase from dropping the car 2" on the 19s. Anyone done so on an 812? The good thing is that unlike the RS, this is an easy change as the 812 has normal wheel hubs instead of the one hole centerlock on the RS. Anyone used slicks?
     
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  3. Solid State

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    Stock the car comes with 20" wheels so 19" wheel is only 1/2" drop from the center point excluding any tire differences.
     
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  4. Frank_C

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    Came from a PCA instructor who’s DEd the .1 and .2 RSs and turned his .1 into a .2 with springs and diffuser, etc. I don’t understand set up math and spring settings, bar stiffness, camber and tie settings. But as I understand it drops front lip 2” not axle height 2”.

    Regardless I just am interested in putting slicks on the 812 if I can and will it take the extra grip.


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  5. Il Co-Pilota

    Il Co-Pilota F1 Rookie
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    Not sure you are going about this the right way.

    Let's get the wheels themselves out of the way. You can fit 19" wheels on the 812. So that in itself is not the problem. The issue lies within what you wish to accomplish.

    While the 812 is an incredibly capable car in every way, I very much doubt that the suspension is capable of handling slicks. A car like the 488 GTB is not capable of this without modifications. Too soft, too little camber which result in tyres that either skip or roll over. A car like your GT3RS or a Pista is much more capable of handling such a tyre as it was set up for it. When the Trofeo R tyre came out, people thought it would be a great upgrade over the MPSC2, but it was quickly found that the suspension on stock 458 and 488 cars were not up to snuff. Some got around this by adding a ton of camber to prevent the inside of the tyre from lifting, but it was a bandaid - even on the 458 Speciale. Stiffer springs were needed to keep the high grip tyre with a very stiff sidewall in proper contact with the surface. This has through all my years of being a car nut and a tyre geek, been the biggest and most common error I've seen. Grip that overpowers the suspension.

    If I were in your place, I would go about it in another way. You say you want to lower the car for aerodynamic grip. Well, if the air you remove from under the car translates DIRECTLY into downforce, yes this could be the result. However, when you lower the car a lot, you also take away the diffusers ability to work, as there's less air going across it to create the venturi effect. Add to this that the air now going above the car may just be displaced to the sides and up, but without adding actual downforce. One thing Ferrari has worked very hard on, is reducing lift from air going under the car. This is a major priority, not only because Ferrari hates big fins and spoilers, but also because a street car needs some ground clearance. There's a very good chance that you migh do more harm that good in terms of aero grip from excessive lowering. Can you gain a bit? Most likely, but that sweet spot is probably found at a fairly moderate amount of lowering. 25-30 mm perhaps. You need some air under the car for that aero to work, it's not a real aero race car like a GT2 Ferrari.

    When you change the tyre circumference as much as you would have to do for a 2" drop, i.e 4" diameter change, you actually lose a lot of thread patch. What good will more aero do you if you lose a lot of contact patch? Add to this you get a lot less surface for heat dissipation. It's a poor deal all around with such a big car.

    If I were you and wanted to try some seriously sticky rubber on a lowered 812, I would go about it completely differently.

    Get some stiffer springs from Novitec for a start. Then lower the car about 30 mm rear and 35 mm front.

    For wheels and tyres, I would pair MPSC2 R up with a set of Forgeline GS1R Open wheels. 265/35R20 front and 325/30R21 rear on 9.5x20 and 11.5x21.

    Get the car cornerweighted and move the bias slightly towards the front to co.downstate for the slightly narrow front tyres, and use the springs and collars for proper lowering. Then star adding camber, because that will be needed with the sticky rubber. No idea how much as all of this would be purely experimental, but I would use the Pista camber settings for a start. It will not be perfect but I'm sure it will be a suitable place to start.

    At any rate, don't use very small wheels cor lowering, especially without proper data on the aerodynamic properties of your car. My guess is that all you gain is a bunch of tyre wear not to mention a hell of a lot of wear on your diffuser, side skirts and front splitter.

    Stick with a nice diameter but lower with stiffer springs and go from there.

    But hold your horses...

    Personally here's what I'd do to keep it simple, usable and drivable on and off the track.

    TdF PZero Corsa 4 rubber on lightweight Forgeline wheels with stock offset - perhaps adding 2mm rear and removing 1mm front, for just a hint more turn in and oversteer. But removing too much offset from the fronts to push them out even further, will mess up the steering geometry. Removing front offset or adding spacers screw up the roll center completely. It might look cool, but it does all **** for handling.
    Novi springs with only 15mm lowering all around. This mainly for the added stiffness for the added bite.
    Pista spec camber and corner weighting.

    You can do all the previously described things, but my bet is that the last suggestion, my personal choice, will work the best and cause you the least headaches. Once you have gotten the "simple" setup right, then you could try the more oddball stuff. But trust me when I tell you that adding 19" wheels with rubberband profile slicks for tyres, will not do anything good.
     
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  6. Frank_C

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    #5 Frank_C, Nov 7, 2019
    Last edited by a moderator: Nov 7, 2019
    Thanks. What I was concerned about. I know the RS is bullet proof. I guess in this case what is good for the goose is not good for the gander......

    There’s la whole bunch of track specific and general setups on Rennlist for the RSs. Most people don’t track their proper (V12 up front) Ferraris. I don’t street mine as much since I’ve joined MSR. Just not as much fun.

    Only complaint I have with the F12 is major dive under braking. Hopefully sorted out on the 812.

    Any thoughts on Texas heat and tires- was told Dunlops don’t cord as easily as the cup 2s in the RS. How are Pirelli with heat cycles?

    PS wish I could add a signature- my Ferrari is my momentum car...


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  8. Solid State

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    Co-Pilota has given you sound advice. The Novitec springs are close to the VS setup and will remove the dive you mention. The height, balance, corner weighting and camber calibration can be set by a suspension shop familiar with F12/812. Might want to address brakes/fluid if you like to track these cars. Good luck and post your results.
     
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  9. Il Co-Pilota

    Il Co-Pilota F1 Rookie
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    The Pirelli PZC4 fair quite well. Unlike the regular PZ4 it handls heat well. Not sure what to make of your thoughts on Dunlops. My experience. Which I know I share with some RSR instructors and Porsche drivers, is that the MPSC2 is the overall better tyre.

    The PZC4 TdF spec tyre was designed for a car with the power and weight of the 812.
    Compound is softer than MPSC2 but harder than Trofeo R and MPSC2 R.

    The 812 and F12 you have are from the factory set up very differently. The F12 feels to me like it lacks damper - or has too high spring rate. Depends on how you look at it. But it can get really busy in the suspension and bounce a lot sometimes. The 812 is much more planted in this regard, almost opposite in fact. When I say opposite, I say this because one can really feel that the 812 has quite firm damper valving. Not to the point of making the suspension slow, but there's a lot of damper for the spring. This I definitely prefer over a somewhat busy and slightly nervous chassis setup, which I think is a bit of a letdown of the F12. It's a great car with a lot to offer, but the damper/spring rate is off imo.

    This added damper of the 812 really brings up an interesting point. It means that the car has the ability to handle a firmer spring. In stock form the 812 already squats and dives less than the F12, and with springs, good rubber, camber and corner weighting it will become quite the 800 PS front engined weapon.
     
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  10. Frank_C

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    #8 Frank_C, Jun 22, 2020
    Last edited by a moderator: Jun 22, 2020
    Ok. Just came back from a weekend at COTA with my son. We were both running red group with Edge Addicts (2:30s). We swapped driving the 812 & my GT3 RS over the weekend. 812 is stock with 800 miles on it. I haven't yet put Novatec springs in my 812, but have them ordered. My RS is a dot 1 but added a 2" taller wing upright, dot 2 side skirts & wing end plates, an R diffuser, side muffler deletes and a cage, cup 2s and a track set up.

    I totally chewed up my 812 tires on Saturday and put it on the trailer Sunday...pressures just got too high despite bleeding twice and I chewed through the centers (94*F ambient)...for the first time in my life "discretion was the better part of valor." The last session on saturday I was sliding around quite a bit. (one of the GTR drivers behind me said he could see something was wrong) It was hot and in retrospect I should have come in during the sessions to bleed the tires instead of just between sessions. But while the tires lasted, I can say the 812 is an incredible car, one can say almost RS-ish. Very well balanced, easy to toss around and an incredible amount of grip for such a big car.

    Unlike the F12, the 812 will give the GT3 RS a run for its money. The 812's gearing, RWS and brakes relegate the F12 to an almost ran and the F12 is no slouch! The biggest advantage everyone forgets is having the La Ferrari brakes. While the F12 only had the long straight hp advantage over the RS, the RS has a momentum advantage getting on the back straight and a significant braking point (nearly 40 m) advantage over the F12 (weight and lower top end speed) almost nullifying that speed advantage. The F12 just can't rotate as quick as the RS- balance, no RWS and too much up & down. In the twisties, the F12 has to be millimeter precise or you go straight to sea anchor and skip oversteer and you just lose too much compared to the nimbler RS and GT4s.

    The RWS in the 812 really puts the rear end where it needs to be and allows the car to rotate quickly. One doesn't feel the weight of the car during rotation rather the weight is only felt as one gets to the limits of adhesion in the short stuff and maybe a little bit in trail braking. The 812 can be tossed around the esses at similar speeds to the RS with less roll and with grip. Around the carousel entrance and exit speeds are the same. Despite the 25 mph top end speed (150s/170s RS/812) and weight the braking points are nearly identical. With the 812 you just don't lose time in the twisties to the more "nimbler" cars and you really don't hold them up (you're not Mustang guy like in the F12). And that top end advantage you get on the straights is not lost in the brake zones 125-30 m front straight and 150-60 m back straight (RS/812).

    But that's not where the best accolades come from...I had several GT3 RS, GT4 and a GTR drivers make a point to come over to my garage grinning ear to ear to chat as they were thoroughly impressed with the 812. All of them said they couldn't believe how fast a car it is in the turns. My son's coach (forgot what series he runs TA2?) was amazed at how well it turned. One of the (dot 2) GT3 RS drivers said he had to really work hard just to keep up with the 812 in the turns.....and no he did not come close to a point by.....

    So now it's springs and tires for the car....

    I'll post again after I put the Novatec springs on and do some laps (and take the time to lose one lap to bleed tires during a session).
     
  11. wrs

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    So what kind of lap times did you run in the 812?
     
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  13. Frank_C

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    #10 Frank_C, Jun 22, 2020
    Last edited by a moderator: Jun 22, 2020
    As with the RS 32s comfortably. Going again to COTA in the RS with Chin this weekend. Gonna do some right seat time- I learn better through example. My sons coach said he spoke with someone who raced Ferrari’s who said the Pirelli P0 tread is too deep for the heat, weight & power of that track. And like ICP suggested Cup 2s. But they don’t make the rear with the same load rating......

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  14. wrs

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    Wow, I ran PZeros on my 488 and 991tts, never had that kind of damage. I usually got a couple of events out of a set of tires. It must have been really hot on Saturday but I was at the one in July 2018 and it was over 100, still didn't have that kind of damage. You really were over pressure. I always ran starting at 30 and 28, by the end of a session they were at 45-50 and I would bleed them back down. So most of my wear was on the outside.
     
  15. Frank_C

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    #12 Frank_C, Jun 23, 2020
    Last edited by a moderator: Jun 23, 2020
    Exact same here with the pressures. Sometimes drop driver rear 1# for the carousel. A big reason why I did the side deletes on the RS- the sound was just icing on the cake.

    Yes it was a hot one. I also got the brake fluid temp warning for a second as well. I bled them twice during the day. But the damage was already done during the session. Doesn’t take long to heat up the fronts with all that heavy braking.


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  16. Il Co-Pilota

    Il Co-Pilota F1 Rookie
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    I get the same on both a Pista and 488. The.MPSC2 last maybe three 3 hour sessions, and then stock pads are gone too. One of the issues is the lack of camber which creates a ton of understeer. On a 18c day the Pista and 488 tyres spike in the low 90c and I have seen pressures spike above 2.7 bar. I think like all road going Ferraris, the wear in the pic above is just a result of the understeer and low camber our cars have. And on an 812 if you run stock tyres on track, forget about it. They boil after three laps on a twisty track and then they are shot no matter the amount of tread left. Regular PZeros and MPS4S tyres are simply not track tyres. An 812 on track needs either the TdF wheels or an aftermarket set of wheels with GT2RS rubber on it.



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  17. Il Co-Pilota

    Il Co-Pilota F1 Rookie
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    When you get your new springs in, seriously consider getting your car set up for a bit more track stuff. You don't have to go crazy, but two things you should do.

    Add half a degree of camber to each front wheel.
    Then get the car corner balanced and move the weight forward 0.5%.

    This will kille some of The understeer, but it will also put a greater demand on you as a driver. It will not be dangerous, but the safety that helps you as the front starts to slide will be gone. Instead of a car that starts to steer and regain control if you apply the brake during an understeer skid, a well balanced and more neutral car will swap ends. As a performance car it will be much less brutal on tyres as the car will be much more willing to turn and stop, and it will also be more precise and nimble in your hands, but it will not save you and help you the same way a street car with a ton of understeer will. But if you use the ESC and keep yourself in control, it is a great way to enhance the car. Just remember that you might need to take a step back and relearn the cars signals a bit. Additionally you can of course take it from toe out to toe in. This will make the response slower and less darty.

    But if you really want those tyres to live, you need to kill some of that understeer. And lastly, just keep dropping that pressure as it climbs. If you run the TdF set, try 2.25-2.3 bar hot squared and go from there. Just bring a small 12v compressor if there's no shop air. Easy.

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  18. Frank_C

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    That is exactly what that Ferrari racer told my son's coach.

    My 812 is in the shop now, TDF tires have arrived, getting track alignment & balance on Monday. COTA on 7/18. If that doesn't work, it's new wheels with 21" on the rears for the Cup 2s. Have to go up to 325/30/21 & 285/35/20 (as the only load bearing ones available).

    I don't mind a loose rear end......drive a GT3 RS. And the way to go fast in a 911 is to let the rear go.......
     
  19. Il Co-Pilota

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    Hehe, yep let it all hang out:D

    Would you mind sharing your alignment specs?:)

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  20. Frank_C

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    Got the car back. The Novatec recommended track set up is 1.25" down all around and stiffer rear springs. (It also got corner balanced so same distribution.) According to them (via the tech) the stiffer rear springs will make the rear "livelier." The tech who worked on the car had already left, but I'll get the suspension numbers.

    I'm curious as well. The rear camber is very noticeable! As noticeable as the setup my guy put on my GT3 RS. <- He also dialed in some toe out on the rear to really help out on the twisties. Accentuates the twitchy rear under heavy braking, but so what, it's a 911. Taking both cars to COTA on the 18th so we'll see how the TDF tires will compare.

    The only bad thing is now I can't open up the door in my trailer so it is winch up/down and a pole to push on the brake pedal to get N.

    Also, got some bad news about brake wear. Pads down to 5.1 mm from 9 mm. That's after 856 track miles - according to them (Car only has 962 total miles ;) Damn COVID)

    Yup, they told me exactly how many miles I did on track......il Fratello Grande back in Maranello knows everything.......

    And the stance.......makes the car look Superfast-er...


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  21. wrs

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    Hope you got the front lifter. Looks pretty good. Is that the ATT conference center in the background?
     
  22. white out

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    Looks fantastic.

    If you want R888r, you can drop to a 30 series tire for stock wheels (will lower the car). The front will bump to 285.
     
  23. Il Co-Pilota

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    That's not bad for OE pads. They are not made for the track. Note that you cannot go lower than 3mm in thickness, so 2mm left. Contact Vivid Racing and ask if they have any more Pagid RSC2 pads left in stock. Unfortunately Pagid has discontinued the 4580 and 4581 pad shape in the RSC2 compound, but there are still examples out there. They are longer lasting and more of a race compound than the OE pad.
    As an alternative you can look into getting Surface Transforms CCST brake discs. Aside from offering all the "regular" CCST disc advantages, they open up the ability for running the Pagid RSL1 race pads.

    Not sure toe out on the 812 rear is a great idea, but looking forward to hear about it:)

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  24. Frank_C

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    Well I had an interesting day. When I pushed down on the brake pedal (with a pole) to start the car in the trailer I noticed the pedal was soft. Ok. Thought nothing of it. Warmup lap- first brake point the pedal was soft- hmm. Back straight- pedal to the floor outbraked myself, barely made the corner. Made for an interesting day. Somehow when they flushed my brakes they introduced some air.

    I figured out if I pumped the pedal 4-5 times 50m before my heavy brake points I had 80% pedal almost every time I needed it. I only outbraked myself 3 more times the rest of the day. Last session got the brake red warning light- pads are gone (4 track days 1000 track miles).

    The Novatec springs made a huge difference. The one thing I did notice is (not only did they decrease body roll) the stiffer rear springs really loosened up the rear- a wonderful thing as the car now no longer has that dreadful understeer as in the F12. One can now properly plant the rear and aggressively throttle around mid & high speed corners with no push. Not maintenance throttle, honest to goodness planted rear, apply throttle with zero push. And the rotation............. the rotation..........just joyous rotation!!! Just couldn’t do that with an F12.

    As for the TDF Corsa tires, it was 96* ambient at the track and it was greasy. Even the guys driving GT3s and clubsports with slicks were complaining. As the track cooled I finally got the tires to really hook up and was pleased. They maintained pressure well despite getting hot at times. Are they better than the OEM P zeros- hell yeah. Are they better than Cup 2s. Eh, probably not.

    It’s unfortunate I had no brakes from the get go. Despite this I did drop nearly 2 sec from the last event and on a greasy track. Could have been more as the car was hitting 177 on the back straight and had to lift and pump.

    I met Dan from Finspeed wheels who took some pics for measurements and will do some calculations over the weekend and come up with some ideas for Cup 2s.


    ps Out of the blue he asked me how the 812 did on turn 10- I told him first time I drove it I lost the rear and nearly hit the inside wall. Apparently this is a common issue with other drivers as the rear steering gets confused and doesn’t know what to do- go parallel or go out. So it wasn’t me after all. I figured out the best way to handle it is to early apex it with little steering input and just go wide to keep the rear wheels underneath me.




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  25. day355

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    Very interesting comments !

    On my F 12, i ve 4 brand new shock absorbers withe the new reference product for the front, 4 TDF springs 35 % more rigid than stock s F 12,
    TDF ground clearance & alignment.
    Concerning the tires, i installed news Bridgestone S007 , not a half slick, but very near.
    The complete set up change everything, not the same car !!!
     

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