Other than bigger rotors, cross drilled brakes, what are the real performance differences between the Z51 Suspension and regular? Is it worth the $1700 price tag?

 

The short answer is probably yes. A lot depends on what you expect/want from the car. I had a base '05 and it handled quite well except when I took it to an autoX and then its weakness showed through with it getting loose when pushed hard.

The Z51 also gives you larger sway bars and springs and shocks geared for spirited driving. As well you get additional cooling with an oil and transmission cooler that the base (MN6) car won't have (auto's have a trans cooler). Plus the bling factor with the larger brakes is a must for many.

On the downside the Z51 tires will wear sooner than the base cars and are likely not as good when driven through standing water like during or just after a large downpour.

You may want to try and test drive both before you buy.

 

Sway bars and tranny gear ratios. I've read where the tranny gearing equates to a 3.90 rear end. So, you gain a little "spunk" from the stock 3.42 standard ratio. You get WC tires that are very soft and help in corner carving.

That's all I can think of right now.

Elmer

 

The manual tranny has different gear ratios.

__GEAR______Mode__or__Option
____________Z06___Std_6-spd___Z51_6-spd___6-spd_Auto___4-spd_Auto
__1st_______2.66____2.66________2.97____ _____4.03________3.06
__2nd_______1.78____1.78________2.07____ _____2.36________1.63
__3rd_______1.30____1.30________1.43____ _____1.53________1.00
__4th_______1.00____1.00________1.00____ _____1.15________0.70
__5th_______0.74____0.74________0.71____ _____0.85
__6th_______0.50____0.50________0.57____ _____0.67
Reverse_____2.90____2.90________3.28____ _____3.06________2.29

Axle Ratio___3.42____3.42________3.42________ _2.56_____2.73(or_3.15)


Gear Ratio times Rear Axle Ratio
__GEAR______Mode__or__Option
____________Z06___Std_6-spd___Z51_6-spd___6-spd_Auto___4-spd_Auto
__1st_______9.10____9.10_______10.16____ ____10.32_____8.35 or 9.64
__2nd_______6.09____6.09________7.08____ _____6.04_____4.45 or 5.13
__3rd_______4.45____4.45________4.89____ _____3.92_____2.73 or 3.15
__4th_______3.42____3.42________3.42____ _____2.94_____1.91 or 2.21
__5th_______2.53____2.53________2.43____ _____2.18
__6th_______1.71____1.71________1.95____ _____1.72
Reverse_____9.92____9.92_______11.22____ _____7.83_____6.25 or 7.21

 

RPO Z51 is not just a suspension option. It is a performance package.

In addition to what you mentioned above, RPO Z51 package gives you:

• Different transmission ratios (manual, designed for higher top speed in 5th gear)
• Higher spring rates
• Higher dampening rates
• Larger stabilizer bars (front & rear)
• More aggressive tires with a higher speed rating
• Grease zerts on rear outer tie rod ends
• Engine oil cooler
• Transmission oil cooler (manual)

The overall Z51 package gives the car a more performance oriented feel than a non Z51 car.

 

The Tranny cooler is no big deal. You can get Z51 sway bars installed for less then $300 even cheaper if your order them from Gene . You can order Hotchkis Sway bars that are even superior to Gm's Z51. I would rather spend the extra bucks on Koni FSD Shocks and then your car will handle much better then the Z51.

 

The coolers and the cool looking rotors were my reason for buying the Z51 option. I thought a cooler for the MN6 was interesting as most coolers I have seen were for auto's.

 

The Z51 manual is a wider ratio transmission, but note that the automatics are even wider ratio, and can get away with it because of the torque multiplication of the converter. For road racing, a close ratio transmission is favored because engine RPM doesn't drop as much when up or down shifting, keeping the engine higher in the power band, note that the base and Z06 use a close ratio manual.

The Z51 spring rate is higher, too high to use the entire suspension travel without the tires losing contact with the pavement in a car of this weight. This gives less dive on a smooth surface, but will cause skitter/hop on rougher surfaces like ordinary urban streets.

The Sachs Z51 shocks have more jounce damping, giving a harsher ride, but have inadequate rebound damping, leading to wheel hop with the higher rate springs. (The base Sachs shocks have the same problem with the base springs, you need Bilstein or Koni shocks to properly control the suspension with either package.)

The Z51 sways are excellent, nearly perfectly matched to the car's weight and suspension geometry. They are very inexpensive to add to any Corvette, though.

The SC tires are softer compound and give more dry grip, improving cornering and braking, but much poorer tire life and wet or cold weather performance than the base GS2 tires. Both have the same speed rating. At $1700 a set, the more than doubling of tread life for the GS2 tires, and better wet/cold performance, has to be a serious consideration for anyone who is going to daily drive this car.

Note that the automatic cars do not get the extra engine oil cooler, and that all automatics get a transmission cooler. You do get a power steering cooler with the Z51 package. The Z51 coolers may be worthwhile if you're going to compete in a showroom stock class, but if you're going to race seriously you'll want bigger aftermarket coolers anyway. They are inexpensive.

In my opinion, for a street car, you're better off going with the base and adding the Z51 sways and aftermarket shocks. Better ride control and less expense, both at purchase and later when you need tires. If you're going to race seriously, I'd also recommend the base because you'll be throwing away less money when you upgrade to racing components. But if you're buying the car to compete in showroom stock events, then consider the Z51 package. You won't be competitive against a base car with modifications, but you won't be racing in his class.

 

proly gonna order my 08 to replace my 05 with Z51 this time mostly for resale as it's a hot option to have. But I hope to be able to work a deal with the dealer to have the Z51 tires removed prior to delivery and replaced with regular C6 tires. In addition to fast wear I've read that they can be dangerous in cold/wet conditions as they were designed for warm/dry road conditions.

The Z51 package seems to be a good deal to me but I don't think it really makes a C6 that much faster. That would be a tough thing to accomplish since the engine is identical Z51 option or not.

just my opinion

ps. you'll find a lot of discussion about the rotors used on Z51 and F55 if you search. Turns out there is only one 'side' used on the car so cooling is possibly compromised on the 'wrong' side. However, unless the car is tracked I would not think this would be material. Nonetheless, the stock rotors are heavy. Aftermarket suppliers provide two piece rotors that are direct replacements for the Z51 option ones that weigh considerably less. Those who know say this is good. I plan to get slotted instead of drilled replacements since , again, those who apparently should know say slotted OR solid rotors are actually superior to drilled.

 

The Z51 is definitely worth it. I would not get a C6 without it.

 

 

I will soon be ordering a C6 and I'm probably going to go with Z51. I had the base suspension on my C5 and felt it was too "loafy" when driving the car at higher speeds. A set of Z51 swaybars probably would have made me happy.

The main reason I'm going with Z51 on the C6 is lower gearing in the transmission. As someone mentioned, the ratios are a bit further apart, but the overall gearing is lower in 1st, 2nd and 3rd gear. IMO, this makes the car a bit easier to launch from a stand still and makes the base car feel a little more snappy driving around town. I've driven both transmissions with the C6 and I really want the lower gears.

The F55 would probably be a better choice for me because I could do without the harsher ride, but I really want the lower geared M6. If I was getting an automatic, I'd go F55 with the performance axle.

 

Just to add to that a little bit. If you're like me, and you don't like the idea of modding a brand new car too much, the z51 is for you. I'd rather order the factory package than have the headache of finding all these parts separately and finding a shop that will do a great job installing them...

 

My Z51 package on my 08 Vert cost's me $ 1406.85

You can't even buy a set of Goodyear Super Car EMT tires for $1406.85

There is nobody on this forum that can build an ADD on Set of Mods that is anywhere close to what you get in the Z51 Factory Package
for that price, not even if they BUY IT ALL AT WALLY WORLD.

 

comparing Angelina Jolie to Ellen Degeneres.

 

The Z51 compared to Base is like.....

--------------------------------------------------------------------------------

comparing Angelina Jolie to Ellen Degeneres