Ken Roberts
Supporter
Also.....the OEM front Z06 wheels have a 40mm offset and the rear wheels have a 59mm offset.
Shane's SLC Build
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Shane
Supporter
Thought I would add this to the conversation.
You can see why our wheels are sticking out compared to the Z06.
Z06 = 9.5" Width / 2 = 4.75" -> 40mm = 1.575"
This means the wheels street side face is 4.75" - 1.575" = 3.175" from the Mounting face
F14 = 9.5" Width / 2 = 4.75" -> 30mm = 1.181"
This means the wheels street side face is 4.75" - 1.181" = 3.569" from the Mounting face
With the suggested 285 tires, I bet we are almost a full 1" farther out.
I know you all have done the math and understand it and I really appreciate you just letting me document this so I don't forget.
cncwheels.com.au
You can see why our wheels are sticking out compared to the Z06.
Z06 = 9.5" Width / 2 = 4.75" -> 40mm = 1.575"
This means the wheels street side face is 4.75" - 1.575" = 3.175" from the Mounting face
F14 = 9.5" Width / 2 = 4.75" -> 30mm = 1.181"
This means the wheels street side face is 4.75" - 1.181" = 3.569" from the Mounting face
With the suggested 285 tires, I bet we are almost a full 1" farther out.
I know you all have done the math and understand it and I really appreciate you just letting me document this so I don't forget.
Wheel Offset Explained | Understanding Wheel Backspacing And Offset
Still not sure which offset to choose? Before you buy new wheels, get to know the importance of choosing the right rim offset and backspacing for your vehicle.
cncwheels.com.au
Joel K
Supporter
Thought I would add this to the conversation.
You can see why our wheels are sticking out compared to the Z06.
Z06 = 9.5" Width / 2 = 4.75" -> 40mm = 1.575"
This means the wheels street side face is 4.75" - 1.575" = 3.175" from the Mounting face
F14 = 9.5" Width / 2 = 4.75" -> 30mm = 1.181"
This means the wheels street side face is 4.75" - 1.181" = 3.569" from the Mounting face
With the suggested 285 tires, I bet we are almost a full 1" farther out.
I know you all have done the math and understand it and I really appreciate you just letting me document this so I don't forget.
Wheel Offset Explained | Understanding Wheel Backspacing And Offset
Still not sure which offset to choose? Before you buy new wheels, get to know the importance of choosing the right rim offset and backspacing for your vehicle.
View attachment 151126
Shane,
Another thing to keep in mind that was not that obvious to me is the concavity of the spoke design. Wheels with more concave design leaves less room to clear the brake calipers. So with Foregstar, a semi concave wheel design provides more clearance than a wheel with the same backspace and deep concave design. If you look around the Forgestar website, they show the various sizes and you can’t purchase all sizes in all the different concave styles. This is why the 18X10” wide Semi Concave font wheels fit the SLC perfectly and the 19” x 10” or 9.5” wheels stick out.
I have no idea what I was smoking when I looked up those numbers! Corrected again. At least I was right about it being an offset issue
Shane
Supporter
So moving on from the wheels for a bit.
I got the tub temporarily mounted. I had to notch around my brake lines that are running inside.
We got the chassis sitting on blocks so it is level all the way around. I made 5" blocks. The body is now level on all four corners by the wheels. I am sitting at 5.25", which makes sense.
The B pillars are sitting on top of the cross brace (on top of the tub so up ~0.125") The A pillars are flat and solid on the dash cross brace. And the front corners where the foot well is, it is up about 0.3125". I will make a couple of spacers for that.
Overall I am happy with where it is sitting. So I went and grabbed the windshield. And it is way off!
I tried to widen the base of the A posts by using a 2x2. It worked but messed up the alignment of the spider to the pan, like a lot.
What are your thoughts? I have searched a lot today on the forums trying to see what people have done and I really haven't had a lot of success. Can you point me in the right direction?
I got the tub temporarily mounted. I had to notch around my brake lines that are running inside.
We got the chassis sitting on blocks so it is level all the way around. I made 5" blocks. The body is now level on all four corners by the wheels. I am sitting at 5.25", which makes sense.
The B pillars are sitting on top of the cross brace (on top of the tub so up ~0.125") The A pillars are flat and solid on the dash cross brace. And the front corners where the foot well is, it is up about 0.3125". I will make a couple of spacers for that.
Overall I am happy with where it is sitting. So I went and grabbed the windshield. And it is way off!
I tried to widen the base of the A posts by using a 2x2. It worked but messed up the alignment of the spider to the pan, like a lot.
What are your thoughts? I have searched a lot today on the forums trying to see what people have done and I really haven't had a lot of success. Can you point me in the right direction?
I kept the same tires and ordered front wheels with different offsets, it was super difficult to sell the old set, I finally sold it for $600 through ebay after several months. Yes a huge f-- up wby RCR, thay have known about it for a long time.
I went in between, moved it a little out, it still had a significant gap on the windshield but not as large missfit on the tub. some people have secured the body at the right fitment with the tub and then push out the fiberglass around the windshield by using spacers against the cage or at the corners of the spider, where it sits on top of the footwells. The problem with that approach is that you will have tension on the windshield if you need to remove the spider after the windshield is mounted and will likely crack. Or I guess you could remove the windshiled first.
Whatever you do . DO NOT try to bend the windshield, DO NOT put stress on it, it will crack.
Shane
Supporter
After thinking about this overnight I think I am going to mount the spider and then start building out the body to match the windshield. I know that is a lot of work but I think that is the right way.
What do you guys think about cutting the A pillars off and then re attach them to match the windshield . I know I would have to build and modify the doors, but that might be the easiest way. Thoughts?
What do you guys think about cutting the A pillars off and then re attach them to match the windshield . I know I would have to build and modify the doors, but that might be the easiest way. Thoughts?
Joel K
Supporter
Shane, as you probably found, there are a few different methods that builders have used.
1)Build up the a-pillars and make the spider fit the windshield. One builder also added a ridge in the door to match the new profile of the windshield area.
2)Stretch the spider then lock it down so the windshield fits better. In some cases the roof then wants to come down so that needs to be addressed. As you see the sills no longer meets up with the interior tub and also the front clam may no longer clear the lower windshield area. So some trimming and re-profiling needs to be done. I’m thinking when you stretch the spider, have the front clam installed and stretch that at the same time.
Colin used some airbags to widen out the spider against the roll hoop and it worked well. My thinking is if you leave the body in that position for a few weeks the fiber glass may relax and hold that shape. Also apply some heat to the pillars with a heat gun may help. Perhaps just move it out a little bit each day so you don’t crack anything.
I tried using some shims agains the roll hoop and left it there for a few days and the body retracted right back. Also, the roof came down too much and then the windshield was too tall.
3)Spread the body slightly and lock it down, then when installing the windshield close the gap with some wood clamps against the windshield without applying too much force. Allan has this technique down, but I am not bold enough to try this,
I’m not 100% sure what direction I’ll go but leaning to make the body fit the windshield by either building it up or cutting the lower corners and bringing them out a bit. I saw Dan Carter’s car in person and thought it looked good. He did not re-profile the door edges, but felt it was a good solution.
Here are some pics..
Dan built up the a-pillars, Kyle’s was installed by Allan, Johan shaved down the top of the a-pillar and stretched out the bottom of the a-pillars.
Hope this helps. Keep us posted on how you approach it..
1)Build up the a-pillars and make the spider fit the windshield. One builder also added a ridge in the door to match the new profile of the windshield area.
2)Stretch the spider then lock it down so the windshield fits better. In some cases the roof then wants to come down so that needs to be addressed. As you see the sills no longer meets up with the interior tub and also the front clam may no longer clear the lower windshield area. So some trimming and re-profiling needs to be done. I’m thinking when you stretch the spider, have the front clam installed and stretch that at the same time.
Colin used some airbags to widen out the spider against the roll hoop and it worked well. My thinking is if you leave the body in that position for a few weeks the fiber glass may relax and hold that shape. Also apply some heat to the pillars with a heat gun may help. Perhaps just move it out a little bit each day so you don’t crack anything.
I tried using some shims agains the roll hoop and left it there for a few days and the body retracted right back. Also, the roof came down too much and then the windshield was too tall.
3)Spread the body slightly and lock it down, then when installing the windshield close the gap with some wood clamps against the windshield without applying too much force. Allan has this technique down, but I am not bold enough to try this,
I’m not 100% sure what direction I’ll go but leaning to make the body fit the windshield by either building it up or cutting the lower corners and bringing them out a bit. I saw Dan Carter’s car in person and thought it looked good. He did not re-profile the door edges, but felt it was a good solution.
Here are some pics..
Dan built up the a-pillars, Kyle’s was installed by Allan, Johan shaved down the top of the a-pillar and stretched out the bottom of the a-pillars.
Hope this helps. Keep us posted on how you approach it..
Attachments
I dont recommed cutting the A Pilars, you will be chasing your tail with the roof and the doors, the doors are hard enough as it is, also if you shimmy the spider you have to think what will happen if you need to remove the spider in the future. the windshiled will be under a lot of stress. You may not, but you have to think about it as a possibility . As Howard wisely said. you probably will have to remove and reinstall every part of the car a few times during the build. He is 100 percent right .
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Shane
Supporter
AC Condenser Brackets and #6 Pipe routing
Here is how I made the AC condenser mounting brackets. I also mounted the dryer and switch. I think I will paint the dryer but maybe not. I designed the brackets and used SendCutSend. I have attached them here if anyone ever wants to used them or modify them. I also worked with Mason at Gemini Ultimate to design the fan shroud. Like Ken mentioned the fan shroud should have a divider that isn't in the current design.
Here is how I made the AC condenser mounting brackets. I also mounted the dryer and switch. I think I will paint the dryer but maybe not. I designed the brackets and used SendCutSend. I have attached them here if anyone ever wants to used them or modify them. I also worked with Mason at Gemini Ultimate to design the fan shroud. Like Ken mentioned the fan shroud should have a divider that isn't in the current design.
Shane
Supporter
Back to wheels.
I talked to Forgestar and this is what I have found.
My wheels are F14 19x9.5 with a 6.4375" backspace. I want to move the wheel in 0.75" So the new backspace would be 7.1875"
From Logan at Forgestar "Perfect! With that backspace I can do a 19x9.5 +50 which is that exact backspacing which shifts the wheel inward .75". He also said it moves the wheel to a semi concave giving the wheel to caliper more room.
I made a mold today of the caliper to spoke profile. Blue line is the caliper and the red line is the spoke. I have almost 1" of room.
It is an expensive mistake by RCR. The quoted price for the wheels is
19x9.5 (raw finish): $548 each
Pair: $1096 plus tax. Free shipping!
Not sure what the other options are?
This is risky and I don't like it but has anyone thought about cutting 0.75" off the lower A arm? This would move it in. I think there is enough stroke on the shock to handle it. I just don't like messing with that geometry.
I talked to Forgestar and this is what I have found.
My wheels are F14 19x9.5 with a 6.4375" backspace. I want to move the wheel in 0.75" So the new backspace would be 7.1875"
From Logan at Forgestar "Perfect! With that backspace I can do a 19x9.5 +50 which is that exact backspacing which shifts the wheel inward .75". He also said it moves the wheel to a semi concave giving the wheel to caliper more room.
I made a mold today of the caliper to spoke profile. Blue line is the caliper and the red line is the spoke. I have almost 1" of room.
It is an expensive mistake by RCR. The quoted price for the wheels is
19x9.5 (raw finish): $548 each
Pair: $1096 plus tax. Free shipping!
Not sure what the other options are?
This is risky and I don't like it but has anyone thought about cutting 0.75" off the lower A arm? This would move it in. I think there is enough stroke on the shock to handle it. I just don't like messing with that geometry.
Joel K
Supporter
Shane,
Based on all my measurements, the F14 19x9.5 with deep concave style with 7.1875 backspace will interfere with the calipers.
The most you can do is possibly 6.749 backspace which leaves 2mm to the caliper. That has zero margin of error if the measurement wasn’t dead on. At most with a margin of safety is 6.7” or 6.65”
If you want that much movement in, the 19X9” is the better choice, but you will need new tires.
Based on all my measurements, the F14 19x9.5 with deep concave style with 7.1875 backspace will interfere with the calipers.
The most you can do is possibly 6.749 backspace which leaves 2mm to the caliper. That has zero margin of error if the measurement wasn’t dead on. At most with a margin of safety is 6.7” or 6.65”
If you want that much movement in, the 19X9” is the better choice, but you will need new tires.
Ken Roberts
Supporter
His proposed new front wheels will be a "semi" concave. I assume his current front wheels are a "deep" concave.
Definitely do not modify the lower A arm.
Definitely do not modify the lower A arm.
Joel K
Supporter
Ken,
Forgestar does not make F14 19x9.5 or 19x10 in semi concave. Only deep concave. They make a 19x9” semi concave.
Ken Roberts
Supporter
Did I misread what Shane said in post #152? He claims Logan said it would be a semi concave.
Joel K
Supporter
You read it correctly, but I went through this with the regional manager and they don’t do a semi in that size unless something has changed. I just checked the web site and semi in 19.5x9.5” is not listed.
If they did, it would solve the problem.
Shane
Supporter
Thanks guys so much for checking me on this. It is really helpful and I want to get it right. Here is my measurement, I'm calling it 6 7/16" or 163mm. So that is where I get the 7.1875" backspace. And yes, Logan from Forgestar said it would change it to semi concave. I will double check with him tomorrow.
The measurement is in inches on the caliper. You can see I have almost 1" from the spokes to the caliper and that checks with my tape measure. I did the mold just to make sure I wasn't missing something. Do we have different calipers? Mine were the Camaro ones.
The measurement is in inches on the caliper. You can see I have almost 1" from the spokes to the caliper and that checks with my tape measure. I did the mold just to make sure I wasn't missing something. Do we have different calipers? Mine were the Camaro ones.
Joel K
Supporter
For comparison. My backspace measured 6.375-6.4” on a 9.5” wide rim and have the 2010 Camaro SS Calipers. Here a pic showing a 3/8” block between the caliper and spoke. Clearly not close to a 1” gap.
Are you sure you have 9.5” rims and not 10”? the size should be embossed on the rim.
Are you sure you have 9.5” rims and not 10”? the size should be embossed on the rim.
