Joel K
Supporter
Thanks Murray, this is very helpful. Can you post a couple pics of your tires? To show the amount of poke and also how they fill out the wheel well.
Front tire poke at zero toe and zero camber
- Thread starter Jkviper
- Start date
Joel, Body and front / rear clams are off the car as we speak ( Go kart stage ) so sorry, no pics. The tyres did sit nicely within the front clam - just fine. Having built 4 Cobras, I was mindful of wheel offset ( enough to fill the arch, but next to no tyre protrusion )
When I set up the suspension, I started by adjusting lower A arm inboard ends in almost as far as they would go - pulled in a smidgen of camber and adjusted caster with the upper A arm. Steering links you spoke of, were not a problem - plenty of thread on rack ends.
I will also be changing those alloy steering arms that connect to the spindle / upright - to mild steel ( they look a bit frail to me )
Joel K
Supporter
Ok, a little more data to try to figure out the possible issue and fix.
The backspace on my F14 19”x9.5” front rims are 6.375”. Also, I can fit a 3/8” block of aluminum between the caliper and the spoke with maybe 1-2mm to spare.
Some of the compiled backspace info so far:
Stock 18” Z06 Rim backspace as per Ken is 6.82”
Murray’s 18”x 9.5” Rim backspace is 6.9”
Chris’s 19”x10” Rim backspace is 7-7.25”
Bill from RCR measured two different 19”x9.5” wheel backspace of 6.427”
Clearly my rims have the least amount of backspace. I viewed the Forgestar backspace chart and each wheel design has different concave profiles which determine how much backspace you can have before the wheel hits the caliper so it’s not that simple. Also depending on wheel size, the concave profiles for the same rim style are also different. For example, for the F14 Wheel style, a 18”x9.5” wheel is flatter or less concave than a 19”x9.5” wheel,
Below is a pic of the gap between the spoke to the caliper with the 3/8” block. Now I’m wondering if the wheel can be modified to remove about 5/16”, that would leave about a 2mm clearance. From what I understand that should be enough clearance and should get the top of the wheels closer to the top of the fender. Still not tucked in, but mayb the issue is part too little backspace and the style of the F14 19” rims.
The backspace on my F14 19”x9.5” front rims are 6.375”. Also, I can fit a 3/8” block of aluminum between the caliper and the spoke with maybe 1-2mm to spare.
Some of the compiled backspace info so far:
Stock 18” Z06 Rim backspace as per Ken is 6.82”
Murray’s 18”x 9.5” Rim backspace is 6.9”
Chris’s 19”x10” Rim backspace is 7-7.25”
Bill from RCR measured two different 19”x9.5” wheel backspace of 6.427”
Clearly my rims have the least amount of backspace. I viewed the Forgestar backspace chart and each wheel design has different concave profiles which determine how much backspace you can have before the wheel hits the caliper so it’s not that simple. Also depending on wheel size, the concave profiles for the same rim style are also different. For example, for the F14 Wheel style, a 18”x9.5” wheel is flatter or less concave than a 19”x9.5” wheel,
Below is a pic of the gap between the spoke to the caliper with the 3/8” block. Now I’m wondering if the wheel can be modified to remove about 5/16”, that would leave about a 2mm clearance. From what I understand that should be enough clearance and should get the top of the wheels closer to the top of the fender. Still not tucked in, but mayb the issue is part too little backspace and the style of the F14 19” rims.
Joel K
Supporter
Last piece of the puzzle.
I measured the dish in each wheel and I was surprised to see the fronts have deeper dish than the rears. The shallower the dish, the more room you have for the calipers and deeper backspace.
Now I’m thinking the fronts need to have less concave shape and more backspace. Pic of the front dish measurement…
Pic of the rear dish, it is .25” less than the front…
Just for kicks I put the rear wheel on the front to see how it fits…
Now because the dish is shallower, it had almost .75” clearance to the caliper….
So, if anyone can measure their dish front vs. rear I’d be interested in what you come up with.Thanks!
I measured the dish in each wheel and I was surprised to see the fronts have deeper dish than the rears. The shallower the dish, the more room you have for the calipers and deeper backspace.
Now I’m thinking the fronts need to have less concave shape and more backspace. Pic of the front dish measurement…
Pic of the rear dish, it is .25” less than the front…
Just for kicks I put the rear wheel on the front to see how it fits…
Now because the dish is shallower, it had almost .75” clearance to the caliper….
So, if anyone can measure their dish front vs. rear I’d be interested in what you come up with.Thanks!
