JUIC3D

In the endless quest for faster ETs, I'm looking to downgrade my factory Z51 brakes with C5 base.

I already have the fronts here but was debating on swapping the rears as well.

Does anyone know if there is a size, and more importantly a weight difference between the 2?

Also, what else is needed to retrofit the C5 rears onto the C6? I assume I'll need new brackets but is there any other special modifications that are needed to make it work?

Thanks in advance

el es tu

c6 base rear rotors are smaller
they use different brackets (carriers)
weight i dont know and it will vary with manufacturers

cheap rotors and pads:
(btw the c6 front base rotor is also the same size as the c5 base and they are also smaller/lighter than the c6 z51)
these people are experienced with corvettes and should be able to put a package deal for what you want
http://www.knsbrakes.com/searchResults.php?car_id=249

parts taxi sells the carriers: http://www.partstaxi.com
very low (sometimes the lowest) prices
cheap shipping

another cheap option for the carriers is gm parts house

vettenutchas

I have a set of base rear rotors and brackets in excellent shape if you are interested, converted to Z51 size with only a couple thousand miles on a 2009. chasm47@gmail.com

JUIC3D

Email sent

Tommy D

C6 base fronts weigh approximately 19.6 pounds and the rears 14.8 pounds.

JUIC3D

Hm, so the base rotors are 1.6 lbs more per side than these 2 piece I bought. I'm anxious to see what the Z51, being bigger, weigh. I'd love to see 3-4lbs off per side.

Thanks Tommy

el es tu

if you want a cheap way to get lighter rotor (at least up front), the base rotors and the z51 size rotors both come in two piece slotted versions from dba and are 399 for the front set at kns.

JUIC3D

I ordered and received the DBA from KNS a couple days ago. I don't want to have to run my adapters for my skinnies, so I had to go to a smaller diameter rotor up front so they clear.

Here is what they look like.



And as a side note, to whoever jumped in and bought the C5 rear rotors and brackets from vettenutchas, I hope you are extended the same courtesy in the future as you extended me .

I emailed vettenutchas within literally 2 minutes of him posting in my thread and I get a reply back 16 minutes later saying he already sold them to "another forum member who saw your post and bought both the brackets and the rotors."

I've dealt with some rude people in my life, but that is on a different level.

HOXXOH

I posted the differences a while back, but can't find the thread now.

Here's just the basics from my records.

Changing all 4 Z51/F55 rotors to base rotors resulted in a 15# +/- .2#reduction.

Both sets of rotors had been turned once and the base rotors were drilled to appear like the larger ones. The brackets themselves accounted for a full pound of the 15 pound difference.

JUIC3D

Great info, thanks Tom. 15# of rotational weight is huge.

badazz96z28

That transaction was wrong on 2 parts, not just 1. Most would of thought being the offer was posted in the thread YOU started, you should have 1st opportunity to purchase the item. Bad business on both Seller & Buyer

JUIC3D

I agree but there's not much I can do. Some people are rude scumbags and that is just the way the world turns thanks to internet anonymity.

Anyway. I can just order a set of new brackets from Gene at GM Partshouse if I need to.

HOXXOH

Don't get too excited about rotational weight. I've done testing that shows it's not much different than dead weight. A factor of 1.2 when the weight change is somewhere around 10" from center is about all you can expect.

Claims of 5-8 times the weight differences are wild exagerations.

JUIC3D

Without factoring in the rotational weight, it should still be 35-40lbs off the front end, depending how much the Z51 front rotors weigh over the 18lb 2-piece.

I'd love to add more power to the car, but I don't know what else I can do and still remain cam-only.

EWP: no thanks
FAST: not worth the money in my application
NW102: ^
I guess I could port my stock LS3 manifold, but considering the Katech engine dyno only saw like 5hp at the crank, I'm not sure that's worth it.

My only other option for going faster is dropping weight off the car which brings me to this very thread.

Thanks for the input Tom

corvet786c

Well there is acouple of other options if you are interested. Diffrent heads like trickflow 235's or nitrous.

JUIC3D

Ya, but then the car wouldn't be in the same 'class'. Nitrous will probably go on before the end of this year but I'm still trying to make up my mind.

HOXXOH

One of the local guys says "Nitrous is like a hot chick with a STD. You want to hit it, but are afraid of the consequences."

Be safe and live long.

JUIC3D

I've heard that one before. I love it

HOXXOH

I found a little more info from my switch to base rotors.
The scale I generally use for stuff under 10# reads in .1# increments. One of my other scales (0-150#) is +- .2#. I check all scales monthly against weights certified by the AZ Dept of weights & measures.

The ones I took off were Z51/F55 rotors. They had been turned once for a cleanup prior to new pads. I use these during the non-racing season. Fronts were 21.2 and 21.0. Rears were 19.6 and 19.4.

The base rotors were also turned and drilled to match the appearance of the larger rotors. Those fronts were 18.8 and 18.6. The rears weighed 14.4 each. BTW, the drilling accounted for almost .8# IIRC.

I had all my rotors zinc plated, but that added less than 1 oz. each.

The rear brackets were 2.6# vs. 2.1# for the base.
Front bracket was 2.9#, but I didn't write down a weight for the base ones.

The base rotors cool different than the larger ones. They are all bi-directional and the rears pull air in from the inboard (correct) side. I don't have a clue why GM put a cooling duct on the inboard side, yet the rear rotors get their internal cooling air from the opposite side.

The C5 fronts are side specific, due to the cooling vane direction, and the same diameter as the C6 base rotors. The larger C6 front's cooling vanes are identical, making one side correct and the other side wrong.

Base rotor


Z51/F55 rotor


There's a lot of base rotors and brackets just taking up space in garages where the owners have swapped to the larger stuff. Some of that can be at give-away prices or even free.

JUIC3D

That's some great info Tom, thanks for sharing.

So your Z51 fronts were 21lbs after being turned? I weighed these c5 fronts and they were 18. I thought the fronts would be heavier but still, 6lbs is 6lbs.

I wouldn't mind picking up a set of C5 rears for some more weight savings but I'll have to see if I can find a used set somewhere.

I'd probably get new rotors but the brackets should be just fine used.