4 Corner Winter Project

[XfireZ51]

Thought I'd start a new thread since my other one has expanded beyond just new rubber. We're moving onto reducing rotational mass w lighter rotors, plus upgrading rear trailing arm mounts and tie rod brackets.


Had discussion w Pete on possibly massaging the cylinder heads some more, but our concensus was that motor feels pretty strong right now. Bang for the buck not as strong as maybe looking in other areas. With updating my Invos to
Mich SS, I started looking into the whole rotational mass thing. Seems that this is an area that would yield better results in terms of ROI. The Michelins will add a total of 10lbs over current tires. Also, the Z06 brakes are large w front rotors weighing in at 28lbs. ea./rears 20lbs. ea.
Been researching the alternative rotors and have found two that look up to the task. The preferred rotors by the Z06 crowd is the Coleman 2pc. rotors built by Performance AFX. These rotors weigh 17F/15R. They basically reduce rotating mass by 30lbs overall w 20lbs coming off the front end. Rule of thumb is 1lb ~1hp. On the dyno that should mean about an 8-10hp pickup since the front wheels aren't going anywhere.
However, the mitigating factor is that the new rear tires will be ADDING a total of 6lbs. The rear weight loss will net out at 4lbs. The net weight loss on the front after new tires will be 16lbs for an overall net weight reduction of 20lbs.
Pickup of 20hp to the wheels would be huge. Other benefits are quicker steering and shorter braking distances.

Rear Rotors(pic) are made to accommodate the Z06 eBrake. Side view is of front rotor.

[RussMcB]

Thanks. I look forward to following this thread.

[XfireZ51]

Holy Smoke! Just got the rotors. Woah! Pics to come. Fronts at 16lbs, rears 14.5.

[alnukem]

Hi.....question, do you have C6Z06 Brakes all around?

[XfireZ51]

Hi.....question, do you have C6Z06 Brakes all around?

Yes.

[Dynomite]

I started looking into the whole rotational mass thing. Seems that this is an area that would yield better results in terms of ROI.

I am thinking :p

The Winter Project (http://www.corvetteforum.com/forums/c4-zr-1-discussion/3756290-4-corner-winter-project.html)

So.....a loss of 1lb makes the equivalent of 1hp gained? Or is this just in rotational weight?
Horsepower Losses from Angular Acceleration of Rotational Mass (http://www.corvetteforum.com/forums/c4-zr-1-discussion/3756290-4-corner-winter-project.html#post1591155636)

[alnukem]

So.....a loss of 1lb makes the equivalent of 1hp gained? Or is this just in rotational weight? Sorry...........I was never the sharpest tool in the shed! Thanks.

[XfireZ51]

So.....a loss of 1lb makes the equivalent of 1hp gained? Or is this just in rotational weight? Sorry...........I was never the sharpest tool in the shed! Thanks.

Al,

I have searched other forums, other brands and there are several w threads on this subject. The results of the tests appear to indicate that level of return. As I posted elsewhere, other benefits include less sluggish steering and braking. The Z06 rotors are massive. Dropping 22+lbs on the front end and 12 on the back gotta help. We'll see how much.

http://highboostforum.com/forum/showthread.php/25845-Dyno-testing-light-weight-rotors?p=167934#post167934

[alnukem]

Great stuff! Thanks for educating me. I know a lot of us have lightweight flywheels, but I don't think it's quite as "free lunch" as something like rotors, wheels or a driveshaft would be. Is there any other areas that would be "bang for a buck" improvements?

[efnfast]

Al,

I have searched other forums, other brands and there are several w threads on this subject. The results of the tests appear to indicate that level of return. As I posted elsewhere, other benefits include less sluggish steering and braking. The Z06 rotors are massive. Dropping 22+lbs on the front end and 12 on the back gotta help. We'll see how much.

http://highboostforum.com/forum/showthread.php/25845-Dyno-testing-light-weight-rotors?p=167934#post167934
I remember mailing those rotors to you Dom. They were some heavy!

[Fully Vetted]

Dom, you've got 19" wheels to accommodate those big rotors, correct?

[XfireZ51]

Dom, you've got 19" wheels to accommodate those big rotors, correct?

That's affirmative although the rears are only 13" rotors. The fronts are 14's and 18" wheels clear them and the calipers.

[Dynomite]

That's affirmative although the rears are only 13" rotors. The fronts are 14's and 18" wheels clear them and the calipers.

OK......on the Front you have 14 inch diameter rotors.
On the Rear you have 13 inch diameter rotors.

For the New Rotors........
1. What is the weight of the Front and Rear Rotors?
2. What is the weight of the Front and Rear tires including the rims?
3. What is the outside diameter of the Front and Rear Tires?

For the Old Rotors......
1. What is the weight of the Front and Rear Old Rotors?
2. I shall assume the same wheels (rims with tires) Before and After installation of New Rotors?

I shall assume you hit 120 mph in the quarter mile using old rotors and you want to know increase in horsepower available using lighter New Rotors?

The outside diameter of the wheels and top speed is to calculate the wheel/rotor angular acceleration (shall assume it is constant from 0 to 120 mph) in the quarter mile. It will be tricky to calculate the Moment of Inertia of the wheels but I shall assume most of the weight is concentrated toward the outer part of the tire itself. I shall also assume the Rotor weight is uniform from the center outward but in actuality the center separate hub is less weight. I shall (maybe) neglect the weight of the hub, bearings, wheel studs and bolts since such small diameter of hub.

I will also calculate the TOTAL Front and Rear Horsepower Savings on Asphalt in the quarter mile when going from the Old Rotors to the New Lighter Weight Rotors. See Item #2 for some initial Calculations Horsepower Losses from Angular Acceleration of Rotational Mass (http://www.corvetteforum.com/forums/c4-zr-1-discussion/3005470-tech-info-lt5-modifications-rebuild-tricks-500-hp-9.html#post1588414138)

I might also calculate the mass (moment of inertia) of the inertial DYNO Drum that would give you 10 horsepower savings (on the rear only) in the change to lighter rear total rotor mass even though the actually horsepower savings might be more or less in the quarter mile on asphalt.

[XfireZ51]

Nitto Invos

Front: 28lbs. 25.5"
Rear: 37.4 26.7"

Michelin SuperSports

Front: 28. 25.9" dia.
Rear: 35. 27.2"


OEM Rotors. OEM Rims

Front: 27.5. 25.8lbs.
Rear : 20 27.4

Performance A/FX

Front: 16.5
Rear : 14.5

Rear Axle: 3.73:1

Cliff,

I would also say that since these are 2 piece, the hub represents the majority of the weight savings.

[cvette98pacecar]

They look nice.

[XfireZ51]

Found a very interesting C&D article that was alongside the main topic of C7 Corvette Z51 v Shelby GT350. Forgetting for the moment, the topic of the main article, C&D looked at an interesting aspect of the GT350.
The Carbon Fiber Wheels that are available. They did some testing to see what the effect of 58lbs lower unsprung weight had on performance.
I have attached a pic of a table outlining this. You can see it in the Feb. edition of C&D pg. 18. Significant performance enhancement that I thought was relevant to the discussion at hand.

[XfireZ51]

[QUOTE=XfireZ51;236809]40d in Chicagoland today so took the opportunity to throw on new rotors. Offset is same as stock rotor so wheel fitment shouldn't change.

http://i187.photobucket.com/albums/x198/Z51Xfire/Mobile%20Uploads/image_zpsyvbamo2o.jpeg (http://s187.photobucket.com/user/Z51Xfire/media/Mobile%20Uploads/image_zpsyvbamo2o.jpeg.html)

http://i187.photobucket.com/albums/x198/Z51Xfire/Mobile%20Uploads/image_zpshhnmz2ky.jpeg (http://s187.photobucket.com/user/Z51Xfire/media/Mobile%20Uploads/image_zpshhnmz2ky.jpeg.html)

[WydGlydJim]

I've got Exotic muscle front calipers (brembo)...anyway, I bought a set of new front rotors, and the dang things rub on the calipers....first time I got down on them pretty good, the brakes actually seized, and the car would not roll until they cooled off...
:-x
So the guy at Exotic muscle just told me to start clearancing the calipers with a drimel tool.....seems like I shouldn't have to do this......anyone else ever have this problem, or hear of it....it also cause the rotors to warp, and I had to have them turned....I haven't braked hard since I clearanced them some more...makes me nervous....

:neutral:

[XfireZ51]

Jim,

These are Coleman rotors and as u can see from the pics, they identical with the stock rotors. Read several threads of Z06 drivers using these rotors w the Z06 calipers.

[XfireZ51]

Another "decent" day in Chicagoland today. Really looked like an early spring day. Lovely sunshine. Got the front fascia off and now the rear rotors are on.
Just need to torque the caliper bolts. Difference in weight for the rear rotors is not as dramatic as fronts.
Tomorrow is supposed to be a bit warmer so I will be putting on DRM brackets for rear trailing arms. Next weekend mount rear tires to wheels.

[RussMcB]

... so I will be putting on DRM brackets for rear trailing arms.Would you mind sharing thoughts and maybe pictures of this? I bought them, but haven't gotten around to installing them yet. Thanks.

[XfireZ51]

Would you mind sharing thoughts and maybe pictures of this? I bought them, but haven't gotten around to installing them yet. Thanks.

The installation is pretty straightforward. I've removed and installed dog bones multiple times. Won't really be able to comment on what they do until I finally get car out and have it aligned.

[RussMcB]

The installation is pretty straightforward. I've removed and installed dog bones multiple times. Won't really be able to comment on what they do until I finally get car out and have it aligned.Thanks. Understood. I look forward to hearing about it.

[XfireZ51]

Brackets and rotors are on. Brackets are just a bit tricky since the bolt holes for the trailing arms are spread a bit further apart. That makes for some additional work in lining things up to bolt back together.
It's best to bolt the bottom arm first, then top. Keep things loose until all nuts are on, then torque down. Other possible sequence is to connect bracket onto trailing arms loosely, then bolt bracket onto chassis. This will draw both arms towards chassis rail without needing to line up arms with bolt holes in bracket.
I did not do that preferring to torque bracket bolts first then install arms.
Rotors went on easily. Well made. Dimensions seem spot on.

[XfireZ51]

Front Fascia delivered to BNC Auto Body. It'll be stripped and re-sprayed. Should be back in 2-3 weeks.

[XfireZ51]

Tires have been mounted and balanced. DAMN they are wide. I hope to have
pics next weekend with weather getting warmer. Thinking of pulling plenum and do a quick rebuild on the starter while I'm at it. The thing is, you never know what else you'll find in the "while I'm here" zone.

[Karl]

Would you mind sharing thoughts and maybe pictures of this? I bought them, but haven't gotten around to installing them yet. Thanks.

I installed my DRM brackets today. Took about 1 hour to do both sides. Be careful to not drop the nut in the back into the hold where the screw goes. I dropped two of them on the driver side.

I just unbolted the dog bones from the trailing bracket and then the bracket from the frame. With the dog bones still attached to the knuckle the trailing arm brackets slide out from the bottom.

Very easy. Now I need an alignment.

[Karl]

Thought I'd start a new thread since my other one has expanded beyond just new rubber. We're moving onto reducing rotational mass w lighter rotors, plus upgrading rear trailing arm mounts and tie rod brackets.


Had discussion w Pete on possibly massaging the cylinder heads some more, but our concensus was that motor feels pretty strong right now. Bang for the buck not as strong as maybe looking in other areas. With updating my Invos to
Mich SS, I started looking into the whole rotational mass thing. Seems that this is an area that would yield better results in terms of ROI. The Michelins will add a total of 10lbs over current tires. Also, the Z06 brakes are large w front rotors weighing in at 28lbs. ea./rears 20lbs. ea.
Been researching the alternative rotors and have found two that look up to the task. The preferred rotors by the Z06 crowd is the Coleman 2pc. rotors built by Performance AFX. These rotors weigh 17F/15R. They basically reduce rotating mass by 30lbs overall w 20lbs coming off the front end. Rule of thumb is 1lb ~1hp. On the dyno that should mean about an 8-10hp pickup since the front wheels aren't going anywhere.
However, the mitigating factor is that the new rear tires will be ADDING a total of 6lbs. The rear weight loss will net out at 4lbs. The net weight loss on the front after new tires will be 16lbs for an overall net weight reduction of 20lbs.
Pickup of 20hp to the wheels would be huge. Other benefits are quicker steering and shorter braking distances.

Rear Rotors(pic) are made to accommodate the Z06 eBrake. Side view is of front rotor.


Sorry if this has been asked before but do the C6 ZO6 breaks and rotors bolt directly onto the C4? Less the need for larger wheels if using the 14" rotors?

Thanks.

[XfireZ51]

Sorry if this has been asked before but do the C6 ZO6 breaks and rotors bolt directly onto the C4? Less the need for larger wheels if using the 14" rotors?

Thanks.

Karl,

The C6Z brakes use an adapter similar to the C5 brake adapter. However, it's not the same because the Z06 caliper is pushed further away from the center of the hub using 14" rotors. And u do need minimum 18" wheels with good front clearance.
Whenever I remove those "dog-bone" bolts, I always snap on a small vice grip onto the nut so it doesn't fall into the frame. Sounds like u were able to recover them. You could also duct tape the hole.

[-=Jeff=-]

Karl,

The C6Z brakes use an adapter similar to the C5 brake adapter. However, it's not the same because the Z06 caliper is pushed further away from the center of the hub using 14" rotors. And u do need minimum 18" wheels with good front clearance.
Whenever I remove those "dog-bone" bolts, I always snap on a small vice grip onto the nut so it doesn't fall into the frame. Sounds like u were able to recover them. You could also duct tape the hole.

which nuts are you referring to falling in the frame?

[XfireZ51]

which nuts are you referring to falling in the frame?

The trailing arms bolt to the bracket which is attached to the frame. The nut is on the backside of the bracket facing the chassis. There are holes there which allow the bolt end needed clearance. If you're not careful, the nut can fall into that hole and into the chassis rail.

[secondchance]

The trailing arms bolt to the bracket which is attached to the frame. The nut is on the backside of the bracket facing the chassis. There are holes there which allow the bolt end needed clearance. If you're not careful, the nut can fall into that hole and into the chassis rail.

I dropped one one time replacing the bracket you are referring to on one of our WAZOO member car. Took me 20-30 minutes but was able to fish it out with a magnet on flex arm. Not fun...

[XfireZ51]

Finally got starter rebuilt, re-installed, new plug wires on, plenum bolted down, and finally IGNITION. Motor started up once fuel got to injectors. Ran a bit rich at first but that's somewhat expected given BATT was disconnected.
Fired up and awarded up without much drama. Settled into a nice idle at ~ 850-900rpm. Coolant warmed up and fans kicked on.
All systems normal.

[RussMcB]

We need a "Like" button. :-) :thumbsup:

[XfireZ51]

UPDATE. So the car is now on the road. As part of my winter project, I removed the front fascia to have it repainted. Paint was bubbling and cracking off the bumper. Apparently it was symptoms of painting over paint. I took it to the shop that also did my plenum/cam covers. They had to take the paint down to the plastic. Did a great job w color match. What a PITA all those screws on that hold bumper on.
So took car out for a maiden run w new rotors and tires. Initial impression is that the Michelin SS feel and ride smoother than the Nittos. Maybe because they are new and so not hard. The 345s rub inner wheel well on some dips.
Steering feels lighter. Stops just fine, maybe a bit quicker. SuperSports BITE.
Also, w 285s up front ASR sensors appear to be happy.

[XfireZ51]

Finally installed the lower control arm brackets w Pete's lift and help. Drove the car home w some negative camber showing. Tires cocked in at the bottom.
Got alignment this morning, everything set fine and it seems as if the alignment
cured issues of tire scrapping inner fender well. Car takes bumps w very good control. One bounce and that's it. Really nice ride. Really good control. I'm pleased.
So to summarize:
Lightweight rotors saving overall 36lbs.
Michelin SuperSport 285/345
DRM trailing arm relocation bracket
DRM lower rear control arm bracket
Strip and re-paint of front bumper fascia