Rod C's Ohio RCR40

[Randy Folsom]

My spider does not fit to the cage for crap. It is not symmetrical from right to left. I was afraid the spider was way off, but took to measuring the cage to the chassis first.
(1) The two overhead front to rear bars of the cage are shifted towards the driver and are not in the center of the chassis.
(2) My front hoop has a bit of fore/aft curve along the top "straight" part, especially on the passenger side
(3) Passenger A pillar cage point is more outboard on the bracket while the drive A pillar cage point is centered in the bracket.
(4) I needed to trim the spider at the bottom of the A pillar due to cage interference.
What is really odd is the overhead bars are shifted toward the driver while the front hoop of the cage seems to be shifted toward the passenger side of the car. I do not believe any of this is the end of the world or has any functional impact. It certainly does not look right from the front of the car.
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Rod,

I decided to cut off the front hoop and move the rear hoop behind the FW. There were just too many challenges with retaining the front hoop and many advantages to moving the rear hoop. I am retaining the ability make and install a front hoop, but it will be significantly different.

If you want I can share the plans for the rear hoop I made in Fusion 360.

Cheers, Randy

 

[Randy Folsom]

I started body fitment with rockers and the spider. The edge of my rockers was far from horizontal when placed on the chassis and even further from being flat.
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I tried to heat and adjust with no success. I decided to remove the edge and glass in 1 1/2 x 1/16 aluminum bar. I fixture this to be parallel with the bottom edge and straight/flat. I figured the aluminum would make for a stronger top surface for mounting, body pins, etc. I have some gaps to fill and body work to do, but overall they cam out looking pretty good.
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I will attempt to fit them to the car this evening.

Rod, I found the same issues with the rocker panels. I was planning to use fiberglass mat to correct the edge. I like the idea of using aluminum but I am concerned that the aluminum might expand differently than the fiberglass when heated by the sun and result in cracks. No idea if this is something to worry about. Cheers, Randy

 

[Randy Folsom]

I put my roll cage back on, along with the rear bulkhead. When I tighten everything down, the bulkhead 'bar' between the rear window and lower bulkhead access panel would bow, quite a bit, more than an inch. I tried to slot the bulkhead between the front and rear cage connection with no success. I then noticed the trailing rod connection covers by the rear bulkhead stuck into the cabin past the bulkhead. There was no way I could have installed the lower access panel. The rear bulkhead was out of whack once all connected. If I removed the screws at the bottom of the bulkhead into the tub I could get the bow to go away and maybe get the lower access panel to fit. I have installed a 3/8 thick spacer along the edge of the tub where the rear bulkhead connects. Everything fits a better now.
I am terrible at taking pictures as I go. I will add a few pictures here to help every see what I am talking about.

Rod, I removed the trailing rod end covers. These cars have been around for a very long time and I have never heard of anyone getting speared in the back. Those covers were recently added. If you want to retain the safety aspect that those covers are supposed to provide, you could just rivet a square piece of 1/8” steel plate on to the back of the seat. I mentioned earlier that I am moving the rear hoop behind the FW. One of the advantages is that the hoop foot no longer goes below the bulkhead so the FW can sit about 1/8” lower. I slotted the six lower mounting holes to make that happen. Cheers, Randy

 

[Randy V]

I continue to plug away putting this car together. I have my fuel tanks installed and bolted down. Nothing real exciting there.
I have installed the suspension, front and rear, set everything back on the ground and dialed in the alignment fairly close. I do not have a steering rack yet, so setting front toe is not possible, which makes a wheelbase measurement not quit accurate. Currently I am setting around 95 3/8 on both sides. I could bring the rear in a bit since my lower trailing arms are threaded out a little (few turns). See my first concern below as another potential to shorten wheelbase.
I have few areas of concern I hope others may be able to help me with.
1.) My fronts are not set with bottom A-arm to the front and top A-arm to the rear. My tops are toward the front and bottom are towards the rear. This has given me 5deg of caster. I would have to figure something else out to reduce the caster. This is opposite of most of what I have read.
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Rod - If I read you correctly, you have the shims reversed on your front control arms.
The lower control arm should be shimmed all the way forward (toward front of chassis)
The Upper control arm should be shifted toward the rear of the chassis.
ultimately, you’ll want +5° to +6° (positive) caster.
—
Setting toe without the rack is possible, but you’ll need to fabricate something to connect the steering arms to.
—
Remember that your alignment should be done at finished ride height - that’s generally when the lower control arms are level to the ground. This is true for the rear also..

 

[Randy V]

My spider does not fit to the cage for crap. It is not symmetrical from right to left. I was afraid the spider was way off, but took to measuring the cage to the chassis first.
(1) The two overhead front to rear bars of the cage are shifted towards the driver and are not in the center of the chassis.
(2) My front hoop has a bit of fore/aft curve along the top "straight" part, especially on the passenger side
(3) Passenger A pillar cage point is more outboard on the bracket while the drive A pillar cage point is centered in the bracket.
(4) I needed to trim the spider at the bottom of the A pillar due to cage interference.
What is really odd is the overhead bars are shifted toward the driver while the front hoop of the cage seems to be shifted toward the passenger side of the car. I do not believe any of this is the end of the world or has any functional impact. It certainly does not look right from the front of the car.
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Rod -
You’re in the process of realizing that you’re trying to attach a non-symmetrical body to a perfectly symmetrical (CNC) chassis. Most of us that have built these cars struggled in the same way.
I would advise that you remove the windshield and store it in a safe place.
Take the bolts out of the roll cage and just let gravity keep track of it for now.
Get your alignment done and wheelbase set to ~95”
Wheels on and set to ride height (lower control arms parallel to ground)
Put the spider in place (no screws)
Put the sills in place - held with tape
Put front and rear clams on the chassis
Adjust the rear clam to have the wheels centered in the arches.
Adjust the front clam to have the wheels centered in the arches.
Note - clams should be spaced up 1/8” from sills
Slide the sills fore/aft to align with the clams
Move the spider fore/aft to get a tolerable fit with the clams.
Set doors in place with tape.
You should be able to get a good read on cage fitment at this point. Noting that the factory holes are not necessarily perfect or permanent.
—
Reassess the fitment.
Note that you should have weather stripping in place when final fitting of the doors and rear clam.
Note also that sometimes it takes a bit of sanding on the edges and corners of 5he windshields to make them fit properly. Don’t do this right away - wait until the fitting of the doors is nearing completion..

 

[Rod Chaffee]

Randy V - Thank you for the replies and information provided. I am going to go back to the alignment and verify everything, then move along with body placement again, primarily just to triple check everything to make sure I am headed in the right direction.

 

[Rod Chaffee]

Randy F - I am fairly jealous at the speed you are moving along with your RCR. I am not even going to attempt your pace. Thanks for the input and advice. I am going to take a few steps backward in hopes it will improve my steps forward in the future.

 

[Randy Folsom]

Randy F - I am fairly jealous at the speed you are moving along with your RCR. I am not even going to attempt your pace. Thanks for the input and advice. I am going to take a few steps backward in hopes it will improve my steps forward in the future.

It getting hot here in Austin. I will be slowing down for sure.

I continue to plug away putting this car together. I have my fuel tanks installed and bolted down. Nothing real exciting there.
I have installed the suspension, front and rear, set everything back on the ground and dialed in the alignment fairly close. I do not have a steering rack yet, so setting front toe is not possible, which makes a wheelbase measurement not quit accurate. Currently I am setting around 95 3/8 on both sides. I could bring the rear in a bit since my lower trailing arms are threaded out a little (few turns). See my first concern below as another potential to shorten wheelbase.
I have few areas of concern I hope others may be able to help me with.
1.) My fronts are not set with bottom A-arm to the front and top A-arm to the rear. My tops are toward the front and bottom are towards the rear. This has given me 5deg of caster. I would have to figure something else out to reduce the caster. This is opposite of most of what I have read.
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2.) My front driver side suspension is noisy. It squeaks with up and down movement. I did get in the tub and grind away some weld ends and interference to improve the connection for the top A-arm brackets. They were not sitting flush due to interference inside the tub with welds and such. Improving these mounting surfaces did not help. Could this be because everything is not torqued to spec yet? Specifically the lower A-arm bolts inside the tub?
3.) The lower trailing rod connection is really close to the rear wheel. I am concerned with any in/out movement causing this connection to cut a rear tire. I do not want to cut a rear tire. Should I worry about clearance here? How much clearance should I have?
Picture here shows the area I am describing. I will post a picture of the actual gap later today.
View attachment 140062
4.) I tried to keep the trailing rod connecting brackets at the rear tire 'vertical'. This made it difficult to connect everything, so I let the rotate a bit. Should I worry about these being vertical, or just let them rotate as long as they do not bind? Again, picture to show the area I am describing.
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I am beginning to set on the body & will post about how that process is going.

Rod,
My car’s wheel base is 94.75”. If my limited research is correct, original car’s wheel base is 94.5”. So my wheel base is just a bit too long. I still have one washer on the back side of the aft LCA so I can move the front back 1/16” but the turning radius is already quite limited because the tire hits the fuel tank cover. The lower Hiem joints are inserted 9/16”. The minimum is generally considered to be the diameter of the bolt (5/8”). I have about 1/16” of thread left at the UCA so I might turn both top and bottom in another 1/16”. That will also shorten the wheel base, but not very much.
At the back, I don’t have much thread left on the trailing arms, they are just about fully inserted. I might have enough to bring the rear wheel forward 1/8”. I have the longer control arms that go with the +2 flares so your situation might not be the same.

The lower link bar mount is indeed very close to the tire. I rotated the mount for a bit more clearance. I removed the shock and moved the suspension full travel to ensure no binding of the Hiem joint and then tightened the bolt.

Hope that is helpful. Cheers, Randy

 

[PaulProe]

Randy,
The SAE papers submitted by Ford and the FIA papers from F.A.V. both show the wheelbase to be 95" (2413mm) - You're just a bit short. If you need copies of the documents, let me know

Paul

 

[David mono]

Search for the SAE papers on this forum a PDF can be found.

 

[Neil]

It getting hot here in Austin. I will be slowing down for sure.

Rod,
My car’s wheel base is 94.75”. If my limited research is correct, original car’s wheel base is 94.5”. So my wheel base is just a bit too long. I still have one washer on the back side of the aft LCA so I can move the front back 1/16” but the turning radius is already quite limited because the tire hits the fuel tank cover. The lower Hiem joints are inserted 9/16”. The minimum is generally considered to be the diameter of the bolt (5/8”). I have about 1/16” of thread left at the UCA so I might turn both top and bottom in another 1/16”. That will also shorten the wheel base, but not very much.
At the back, I don’t have much thread left on the trailing arms, they are just about fully inserted. I might have enough to bring the rear wheel forward 1/8”. I have the longer control arms that go with the +2 flares so your situation might not be the same.

The lower link bar mount is indeed very close to the tire. I rotated the mount for a bit more clearance. I removed the shock and moved the suspension full travel to ensure no binding of the Hiem joint and then tightened the bolt.

Hope that is helpful. Cheers, Randy

Does that 1/4" wheelbase difference really matter?

 

[Devin]

Does that 1/4" wheelbase difference really matter?

My “original” skin sill covers were about 1/4” different in length from side to side as well as the non symmetrical dimensions of the front and rear clamshells. I would make the alignment and thrust angle correct to the recommended specifications and be less concerned with the original wheelbase possibly being slightly different which can be made unnoticeable when adjusting the body and gaps.

 

[Randy Folsom]

Randy,
The SAE papers submitted by Ford and the FIA papers from F.A.V. both show the wheelbase to be 95" (2413mm) - You're just a bit short. If you need copies of the documents, let me know

Paul

Paul, Thx much. My very limited research was Tom’s build log. I agree with what others have mentioned about prioritizing making it fit and not fretting over a 1/4”. I am actually hoping I will need to move the front forward so as to provide a bit more clearance to turn the front wheels. Just 1/8” could make a difference. Cheers, Randy

 

[Randy Folsom]

My “original” skin sill covers were about 1/4” different in length from side to side as well as the non symmetrical dimensions of the front and rear clamshells. I would make the alignment and thrust angle correct to the recommended specifications and be less concerned with the original wheelbase possibly being slightly different which can be made unnoticeable when adjusting the body and gaps.

Agreed. Thx much.