Jun 18, 2016

Rolling Chassis

It's been an embarrassing long time since my last post.  I could blame it on a busy job and family, but mostly laziness if I'm honest with myself.  Life gets in the way, but I've been able to achieve a major milestone recently... a rolling chassis!

It's a roller!!!
Several projects completed in the last year to get it to this point....


Rotor runout
In the front suspension post last summer, I discussed measuring the rotor runout at more than spec at ~0.010" but didn't have shims yet to adjust.  They were eventually delivered from McMaster-Carr and they are in place now between the hub and rotor hat.  Tedious work with several iterations of different shims, taking the rotor off & on each time held on by lug nuts, resetting the dial indicator, etc... but finally got it to within Wilwood spec for the front.  Thankfully for the rear, no shims were necessary... probably because the expert build I got for trailing arms, but more on that later.



Stainless steel fuel lines and brake lines
I chose stainless for peace of mind in durability.  The rear crossover line is a stock shape available from various corvette suppliers, but the front crossover line and front-to-rear line were custom to mate up with the Wilwood big brakes I'm using... 14" slotted rotors in the front with 6 piston calipers, 13" slotted rotors in the rear with 4 piston calipers.  It'll stop like a modern sports car!  The need for the custom lines arises from my desire to use an adjustable Wilwood proportioning valve.  The stock one is not adjustable and the aftermarket suspension/brakes I'm using could cause the front-to-rear brake bias to be 'unbalanced'.  The adjustable Wilwood version will allow me to dial it in to fit my new components, but the fittings for the front-to-rear line connection are different from stock.  I formed the shapes with copper tubing and sent them off to Inline Tube to be made in stainless.  I did not want to tackle bending/flaring my own since I had heard working stainless could be a PITA and not a situation where you can tolerate less than perfect fit of course.  Caliper to chassis lines were provided in the Wilwood package, but I did need to get a few adapter fittings and braided hoses to complete it all.  For the fuel lines... all are stainless stock shapes along with rubber hoses at the tank available from various corvette suppliers.



 
 







Steering
The steering is being converted to rack & pinion from Vette Brake & Products.  I wanted modern steering plus it will clean up the engine bay look with the steering box no longer there to butt up to the headers on the big block engine.  Everything came together fine except for one of the driver side bracket supports did not quite line up with its sister bracket.  VB&P were very helpful over the phone and sent me another one, but still did not fit well.  So I took matters into my own hands and cut off the "sail" piece that hangs down, clamped it to the sister bracket it was to bolt to and then welded the sail piece back to its base mounted on the frame.  Cleaned up my welds and had the part powder coated and all is well now.
 



Trailing Arms (built by Gary Ramadei)
After much research, I decided to have the trailing arms built by Gary Ramadei (aka gtr1999 on various corvette forums).  He was absolutely fantastic to work with!  Crazy as it sounds, I've not had the chance to meet him yet but after some phone calls & emails I became quite comfortable with trusting him for this work.  So shipped him the parts and received back expert results.  For my trailing arms, one of them turned out to be bent and needed to be replaced so I decided to replace them both with stock parts.  Gary cleaned up and fitted my remaining parts going the extra mile at every step... such as parallel surface grinding the spacer to really nail down the fine end-play tolerances on expert builds, hand-fitting the stainless parking brake components to work better than stock, and the list goes on.  He even sends loads of pics at each step to keep you informed.  For a complete description of his trailing arm build process, see this post he created on one of the corvette forums...
http://www.digitalcorvettes.com/forums/showthread.php?t=77000


Half-Shafts
I restored my original half shafts by hand cleaning the rust/grim off then giving them the POR-15 rust preventative treatment followed by the color.  For U-joints, I followed Gary's suggestions and used SPICER 5-1350X's.  This is a solid-body joint without a grease fitting, an area where some have failed when subjected to high horsepower.  The half-shaft flanges have to be perfectly flat to get the joints to fit, so you need to bolt the flange to a flat support plate before you work with it to prevent it from bending.  You can make your own plate or buy it from various corvette suppliers.  Here's another post by Gary that discusses the recommended work in detail...
http://www.digitalcorvettes.com/forums/showthread.php?t=76752


"Super 10" Rear Differential  (built by Gary Ramadei)

dusty I know!
After a bunch of research, I eventually decided on having Gary build my rear differential to his "Super 10" specs.  The goal is to have the rear end as strong as reasonably possible to handle a ~500 HP engine when it is eventually finished.  In a nutshell, this diff amounts to a 10 bolt but with 12 bolt internals and thus much stronger than stock.  The build is not cheap, but I am very pleased with the decision and end product... no fear now of rear end issues if I ever decide push the car hard in a club autocross event or something similar.  I recommend again hearing the details straight from Gary so see his post which describes the work in detail...
http://www.digitalcorvettes.com/forums/showthread.php?t=124412




Wheels & Tires
Did a ton of research with respect to fit, style, photoshopping different looks, etc, and finally decided for the front... 18x8 American Racing Polished Torq-Thrust II wheels, 4" backspacing, 245/45/18 Nitto NT555 tires.  And for the rear... 18x9.5 American Racing Polished Torq-Thrust II wheels, 5" backspacing, 285/40/18 Nitto NT555 tires.  The backspacing had to be ordered custom for those wheels but was required to get everything to fit under the wheel well without interference from suspension components, etc.  The big brakes I'm using require 18" wheels, plus I dig the look with the 5-spoke design to show off the brakes.  The front combo is otherwise stock size and backspacing.  The rear is wider than stock because I'm after a meaty look from a rear view and that was about as big as I wanted to go after tons of research on what others have done.  Fitment looks good for now, but I'll be monitoring close areas such as the rear sway bar, the parking brake bracket on the trailing arms, and the transverse spring.

   



Sway Bars
The plan initially was to upgrade the front and rear sway bars to the ones that came with the Vette Brakes & Products suspension package, but I've decided now to go back to the original sway bars.  The front sway bar from VB&P was going to fit up nicely, but not the rear bar.  It didn't quite reach to the trailing arms to mount properly and would likely cause binding in the rear suspension travel since it doesn't have the pivot points similar to the stock sway bar that originally came on '72 big block cars.  So I disassembled my original rear bar, pressing out the old rotted bushings, and had it blasted and powdered coated to match the frame.  The original front sway bar got the same blast and powder coat treatment too because I had researched that the sway bars are designed to work together.  If one is 'overpowering' the other because it is too large relative to the other, the result could be oversteer or understeer issues.  The front sway bar from VB&P is larger than stock, thus the concern of not matching with the stock rear sway bar.  After I got them back from powder coat, I pressed in new bushings to the rear bar and used all new poly chassis bushings with lubricant to prevent squeaks when assembling them to the frame.

expert sway bar help
























What's Next?
Originally, I was going to tackle the engine next and even have it mostly disassembled already.  But after seeing a post on one of the corvette forums where a few people lament on doing the engine too early, I think I'll go on to the body next.  Makes some sense to do the engine next, get it on the chassis, and thus out of the way.  But I know when the engine is done, I'll want to have it dyno'd to be sure all is well... and then it sits idle for who knows how long as I do body work off the frame.  So the plan is now to get the body to the point where there is no more to do until it is back on the frame.  Then I'll stop body work, do the engine and get it on to the chassis, and then lower the body back to the chassis for the final work.  

No comments:

Post a Comment