HANDLING: Tires, suspension, alignment

347 Views 7 Replies 6 Participants Last post by adamk, 2 d ago

Aevus

Discussion Starter · 15 d ago

Was focused for a while on the engine, now back to my favorite topic: handling. I don't know about gen 5 Viper, but all previous gens are not exactly known for their good handling behavior... But the good news is, the Viper platform responds extremely well to upgrades and modifications (at least gen 3-4 platform). I own 5 Porsches before my Viper and now, I finally reached a point where I'm as comfortable and confident behind the wheel as I was with my Porsches. But it took a lot of work to get there...

So, I just swapped BC racing + Swift 12/14kg suspension (up for sale btw) for a new Penske Double + Hyperco springs (14/17kg) and will do all my tires and alignment testing this year with that. Will post in-depth comments later about the Penske/Hyperco kit, but all I can say for now is: Wow.
Is it as good a value as BC racing + Swift? Of course not. Is it overkill for street use? Maybe. Do I regret the purchase? Not the slightest.

Now, tires: Since the beginning, on the rear I run the ACR Kumho 355-30-19 on my stock wheels. Obviously, there isnt tons of options in 345/355 sizes and I don't want street-street tires (even though Michelin PS4 are probably the best street tire option) I want max performance street/track tires.
The Kumho traction is amazing, and frankly I don't miss the Pirelli Trofeo R tricky behavior and the fast wear of my Michelin Cup 2, that I had on my Porsches...

So, on the rear, it's an absolute no-brainer for me: Kumho ACR 355-30-19. In fact I'd buy a dozen of these as back-up if the compound would stay fresh for years... The day they stop producing it will be a very sad day.

As you can see, I didnt mention the Kumho on the front. First, it doesnt fit my stock (18's) wheels. Secundo, I don't quite trust it, and finally I'm not afraid of mix n matchin' front/rear, as long as it works.

For the last year and a half I run Yokohama A052 (295-35-18) on the front and even though I barely tested the combo on the track (4-5 hot laps) I did nearly 10,000 miles on the street and I'm very satisifed with it. I never experienced such mechanical grip on any car I drove in my life. So that's the benckmark for me.

Now, I bought a set of 285-35-18 Falken RT660 and I might also test the new 2023 compound revision Nankang CR-S (275-35-18).

These 3 tires are basically what appears to be the best options that fits the front of our Vipers.

From what I heard and read, the Yoko is the best for grip and probably also for the track. The Falken got the sharpest and overall best steering feel. The Nankang is the cheapest but seems to be as interesting as the other two, especially since they revised the compound to adress the issues with older 2021/2022 compound (heat cycles related).

Will post all my comments in this post once I get the Falken installed.

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Aevus

Discussion Starter · #2 · 15 d ago

Oh and before going further: I have quite a lot of modifications on my gen 3 snake, besides the coilovers. What I feel with tires and alignements might not feel the same on a stock or stock-ish Viper, since it's much tighter than stock.

TKO bump-steer correction kit (a must-have)
TKO control arm bushing kit
TKO adjustable sway bar links
ACR solid sway bars front/rear
IPS sway bars bushings
IPS steering rack solid bushings
Race poly engine mount
Race poly transmission mount
TKO rear shock mounts spherical bearing
Limited Slip Differential (Wavetrac)

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Aevus

Discussion Starter · #3 · 15 d ago

About Alignment now:

Will be my 5th different one, and I can tell you right now that If you don't track your car don't hesitate to trade camber for caster: helps a lot to keep the Viper straight, stable and predictable.
The stock alignment's caster is somewhere around 6 or 6.5 if I remember correctly, which is not optimal. I tried everything between 7 and 8.8 and everytime I raised for more positive caster I liked it. Of course the steering feels a bit heavier, which requires more effort when you park the car, but otherwise it's just beneficial. Obviously, if you track the car a lot, you'll want to keep the camber and since you have to sacrifice camber to get caster, it's a no-go for dedicated track cars....

But since this year I'll keep the beast on the street 95% of the time, I'll sure try even more caster and also as much grip as I can to handle my new engine's 600 lbs torque:

Camber (front)-0.8
Camber (rear) -0.3
Caster (front) 9.5+ or max possible
Toe Total (front) 0,0deg
Toe Total (rear) -0,64deg

So nearly no camber on the rear and some agressive toe-in that will reduce the life of my tires, but at least I'll get the maximum traction I can get. In fact, that's leaning toward an alignment for a drag strip, isnt it?

Drag Racing Set Up – Applications In Motorsport Suspension Secrets

Drag Racing Set Up - The set ups below are taken from a rear wheel drive professional drag racing car. Different chassis types, tyre widths

suspensionsecrets.co.uk

As a reference, my 4th alignment (the one I had last year, before swapping to Penske COs) was that:

Camber (front) -1.5
Camber (rear) -1.1
Caster (front) 8.8
Toe Total (front) 0,10deg
Toe Total (rear) -0,50deg

Which was the most satisfying I had so far, but with BC racing/Swift and stock engine.

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Viper Explorer

· #4 · 15 d ago (Edited)

Aevus said:
Nankang is the cheapest but seems to be as interesting as the other two, especially since they revised the compound to adress the issues with older 2021/2022 compound (heat cycles related).

Oh wow, haven't heard that name in awhile lol. I ran their AT truck tire once like 8 years ago? There was a weird shortage of tires and couldn't get the right size in right spec from not even BFG and even Nitto was like weeks out from ordering and needed tires and that was only brand available in the right size (just under 34s if I recall). Fairly cheap too for an AT. I wouldn't say they were great (def not on level of say Toyo AT3s today lol) but they weren't bad either.

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Ssssnake529

· #5 · 9 d ago (Edited)

One of the biggest handling upgrades I made to my car was installing a Quaife dif.

Changed the car's personality when cornering (in a good way.)

[Edit] Just noticed you have a Wavetrac dif, so I guess you've already figured out the benefits of a torque biasing dif.

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Recluse

· #6 · 5 d ago

Aevus said:
Now, tires: Since the beginning, on the rear I run the ACR Kumho 355-30-19 on my stock wheels. Obviously, there isnt tons of options in 345/355 sizes and I don't want street-street tires (even though Michelin PS4 are probably the best street tire option) I want max performance street/track tires.
The Kumho traction is amazing, and frankly I don't miss the Pirelli Trofeo R tricky behavior and the fast wear of my Michelin Cup 2, that I had on my Porsches...

So, on the rear, it's an absolute no-brainer for me: Kumho ACR 355-30-19. In fact I'd buy a dozen of these as back-up if the compound would stay fresh for years... The day they stop producing it will be a very sad day.

I'm looking around at tires for an 06 with stock 18/19 rims. Are these the Kumhos you are talking about?
KumhoEcsta V720P 355 /30 R19 99Y SL BSW FC
Item #39068

Discount Tire | Tires and Wheels for Sale | Online & In-Person

www.discounttire.com

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Ramtuff

· #7 · 4 d ago

Ive gotten my last 2 sets from here with no problems.
https://simpletire.com/brands/kumho-tires/ecsta-v720-acr

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adamk

· #8 · 2 d ago

Aevus said:
Was focused for a while on the engine, now back to my favorite topic: handling. I don't know about gen 5 Viper, but all previous gens are not exactly known for their good handling behavior... But the good news is, the Viper platform responds extremely well to upgrades and modifications (at least gen 3-4 platform). I own 5 Porsches before my Viper and now, I finally reached a point where I'm as comfortable and confident behind the wheel as I was with my Porsches. But it took a lot of work to get there...

So, I just swapped BC racing + Swift 12/14kg suspension (up for sale btw) for a new Penske Double + Hyperco springs (14/17kg) and will do all my tires and alignment testing this year with that. Will post in-depth comments later about the Penske/Hyperco kit, but all I can say for now is: Wow.
Is it as good a value as BC racing + Swift? Of course not. Is it overkill for street use? Maybe. Do I regret the purchase? Not the slightest.

Now, tires: Since the beginning, on the rear I run the ACR Kumho 355-30-19 on my stock wheels. Obviously, there isnt tons of options in 345/355 sizes and I don't want street-street tires (even though Michelin PS4 are probably the best street tire option) I want max performance street/track tires.
The Kumho traction is amazing, and frankly I don't miss the Pirelli Trofeo R tricky behavior and the fast wear of my Michelin Cup 2, that I had on my Porsches...

So, on the rear, it's an absolute no-brainer for me: Kumho ACR 355-30-19. In fact I'd buy a dozen of these as back-up if the compound would stay fresh for years... The day they stop producing it will be a very sad day.

As you can see, I didnt mention the Kumho on the front. First, it doesnt fit my stock (18's) wheels. Secundo, I don't quite trust it, and finally I'm not afraid of mix n matchin' front/rear, as long as it works.

For the last year and a half I run Yokohama A052 (295-35-18) on the front and even though I barely tested the combo on the track (4-5 hot laps) I did nearly 10,000 miles on the street and I'm very satisifed with it. I never experienced such mechanical grip on any car I drove in my life. So that's the benckmark for me.

Now, I bought a set of 285-35-18 Falken RT660 and I might also test the new 2023 compound revision Nankang CR-S (275-35-18).

These 3 tires are basically what appears to be the best options that fits the front of our Vipers.

From what I heard and read, the Yoko is the best for grip and probably also for the track. The Falken got the sharpest and overall best steering feel. The Nankang is the cheapest but seems to be as interesting as the other two, especially since they revised the compound to adress the issues with older 2021/2022 compound (heat cycles related).

Will post all my comments in this post once I get the Falken installed.

Interested in your BC coilovers up for sale if you still have them. I picked up an 05 SRT about 2 months ago after having a poster on my wall of vipers since i was 14. Just getting into research on good upgrades and during my initial inspection saw that the stock suspension was leaking some juice which i guess they tend to do.

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