TheSkunkWorks

If the class/category rules have little tolerance for moving the camber strut link points, it would seem moving the upper links (1/2 shafts) would likely be against them too. If not, IMHO it's a bit of an oversight open to being exploited (and it should be) by going ahead and raising the diff and then moving the strut bracket back down 0.5".

BTW, addressing this issue would reduce the required static toe, and greatly reduce scrub. Having a large amount of toe is like dragging the brakes. There's better lap times to be had...

Jim_Harrison

BTW, addressing this issue would reduce the required static toe, and greatly reduce scrub. Having a large amount of toe is like dragging the brakes. There's better lap times to be had...[/QUOTE]

You are right, for road racing at higher speeds, toe in or out changes slow you down. On an Auto X course were we rarely get over 70 mph and don't go straight much it is all about corner speed and corner exit.

mpettus

Any luck getting the vette back on the road? How is the road noise with the solid mounts?

I'm Batman

Getting much closer, thankfully.

1mpalss

Hey Batman,
Have you had this out on the road yet? Just looking for a "driver's impression".

1mpalss

Old rearend is out:


I'm raising the shock mount 1.5", which corresponds to the amount I'd like to drop the car:


Another angle:


Nothing is "easy" with this thing. It is turning out to be a lot more work than just rebuilding the suspension!

TheSkunkWorks

1mpalss, I'm just making sure your not actually lowering the diff, as stated in your post's header.

1mpalss

Nice catch on the typo! Yeah, I'll raise the diff in the crossmember. It will lower the car. It's still a pain trying to do it right.
By the looks of the stock setup I can't raise the diff much more than 1.5" or I'd have to cut the floor. I'm going to measure and cut everything for a 1.5" change. I'll tailor the height of the diff with spacers, if required.

TheSkunkWorks

I was hoping that was only a typo.

Also, Captain Obvious won't stop bugging me until I make sure you are aware that you don't have to raise the diff the entire amount by which you wish to lower the car, just enough to address half-shaft attitude...

And, I have to ask, are you just lowering or slamming it?

1mpalss

I'm just lowering the car because the 17" wheels just don't fill the wheel wells. My suspension angles were just about right already so this was the next option.
It was a pain but I finished raising my upper rear shock mounts by 1.5" today. As they say, a picture's worth a thousand words:

This was the prettiest side as I did it last! I really, really, really hate welding upside down.

1mpalss

I took the plunge and modified the crossmember. I started by notching the stock mounting location:


I added a 1/4" steel rib down the middle:


Finished welding it back in with 1/4" plate filling the sides of the gap:


Profile view:


Diff is literally right against the floor:


I may add a 1/4" (maybe a 1/2") aluminum spacer between the diff and crossmember to give it a little breathing room. I think I'll add some 1/8" wall tube on top of the crossmember to gain back the strength I lost with the notch.
In hindsight, I should have just eliminated the rubber bushings and created a steel mounting surface to gain the 3/4" of lift there and called it a day. It would have been a whole lot quicker.

Gale Banks 80'

I'm a bit late to this Tread. As I havnt read the Gulstand article I asume that the main point is that by raiseing the Rear you can lower the car and still have the 1/2 shafts Flat or Angleing down to the Spindels. I meet and talked to Dick Gustrand for 10 minutes at the NCM in 06. As my Car is an 80' with the Dana 44 the mounting is all different but it wouldn't take much to raise the Mounting Tabs on the Frame. I am contemplating installing a Viper Super 44 and could do this all at once. As far as the Viper Rear I have allready found just as many reasons not to do it as reasons to do it and I havn't even started.

1mpalss

"by raiseing the Rear you can lower the car and still have the 1/2 shafts Flat or Angleing down to the Spindels"
Exactly right! My inner half shafts were exactly 1" above the outers already (just about where you want them to be) and my rear was sitting too high.

1mpalss

Here's a shot of my braced crossmember:


More shots of the installed crossmember and diff:




Overall shot:


I haven't had it on the road yet as I still have to finish the interior, wiring, installing the rest of the suspension, and setting up the alignment.

TheSkunkWorks

Looking good, and I especially like that you added a stiffener above the notch. Couple of Q's (for other viewers as much as for any other purpose)...

Did you fab up your own top link hardware or find the bits available somewhere? Sufficient clearance in full bump so as not to interfere?

Are the top links or side yokes floating? If the new top links are now serving as your fixed uppers, you did recalculate that your new IC's are good to go, yes?

Keep up the good work.

1mpalss

Thanks. Yes, the inner yokes were cut-off at the C-clips and they float. The upper links are fixed. I made the setup myself, trying to copy some geometry that Flexusmark published several years ago. The yokes move in and out a tiny bit. I'd be suprised if they moved more than .125" or so during full travel. I should measure it now, as you've got me curious.
Funny you should mention full bump travel, as that seems to be the limiting factor - and a great source of extra work and aggravation! I moved the bumpstops up, notched the frame a little, raised the shock mounts, and still need to notch and raise a section of the floor to clear the upper/outer links.
Stock bump stop setup:


Notched frame and higher shock mount:


Relocated bump stop:

TheSkunkWorks

Sounds to me as if you have a good handle on this. Do keep up posted.

Richard Daugird

I know this is an old thread but any updates???

1mpalss

Almost,
I need to have my new windshield installed and start testing the car. I should be driving it any time now.

Richard Daugird

Did you ever finish the car?