Couple of updates:
1 Tube diameters did not work.
The end bells seam to be the same size so I might be able to grind the welds out and the replace with a 2.5" tube and make a driveshaft. I'll see what Stampie comes up with.
There was a brace bolted across the rear end, we changed that to a welded in brace that we can use to mount the rear seat mounts.
First order of the day was upgrading the tubing bender. Hammer store had the 20 ton air/Hydraulic jack on sale for $79 so not more 10,000 pumps to make a bend. Of course the jack is bigger so we had to re do the front half of the bender frame. We also changed the plate system a bit so we can bend to 100 degrees so that we can plan better for spring back.
Then we finished the front seat mount.
All of this was so we can place the steering wheel in the correct position. We bent up a dash bar out of 1" then got is positioned and marked for cope cuts. That is where we ran out of time. Forgot to take a picture of everything mocked up. All of this required us to think about how we canted the body work to go and consider many future design decisions so it all takes longer than expected.
I did get the gas pedal and brake pedal/master cylinder assembly ready to put in, but need to position the steering to determine exact brake placement. So it is ready to go but not welded in .
On the good news front I am starting a new job tomorrow. Will mean more time on the road and away from home, but more money and more opportunity for advancement in the company.
Congrats on the job. Sorry the bullE36 M3 yard in town didn't have the car they said they had. I have a backup to my idea that should still work without a bunch of money.
I was busy with new job last weeks so not much time to work on things during the week, but we go some things done this weekend.
First mounted seat on tracks, we used the passenger seat slides from the corvette on our race set. We have enough travel for both the tall guys and the short guys to fit.
Then we started on the dash bars
Next test fit steering column
Made a plate to mount the brake booster, master cylinder and brake pedal.
Ready for race car noises
Plan is to mount Q45 cluster in our new dash. We are also going to make a tray across the center of the dash area to mount all of our electronics and keep the wire harness short.
Ummmm, the main hoop is supposed to be behind your head
In reply to Patrick :
The rule is " Maximum of 6" from drivers helmet to roll bar" There is no specification of in front or behind the driver. The picture makes it look much further back than it is. We made it this way so that when the seat is all the way forward or all the way back it is still within specification.
We started on transmission tunnel and firewall today. First was the CAD layout.
We traced this out on some sheet metal but did not get it bend up today. we did make two pieces of the firewall and got them welded in. Didn't take any during pictures but here is a couple of after shots.
The language used to be "within 6 inches of the rear" of the driver's head, i'm not sure what the latest rulebook language is but the drawings clearly show it behind helmet and within 6" from the back of the head. I'm not trying to be a dick, i just think it would suck to show up and fail tech for something in the easy to remedy stage
i've been building cars by the nhra book for 20+ years and never seen anyone try and pull off sitting under or behind the main hoop. Sitting in that position the diagonals aren't legal either because they must pass the body between the shoulder and elbow, which they cannot do if they don't begin to pass the body until they're forward of your torso
In reply to Patrick :
I have not been building cages at all so my expertise ends there, but I did talk with two chassis builders locally about this configuration because of the unusual seating position, and they both said it would be fine. I did not consider the diagonals, and no one brought that issue up when I was discussing this roll bar. The problem with moving the bar further back is I run into the rear wheel well and the rear bars are then too steep. Guess right now only the short drivers are legal.
In reply to Patrick :
I didn't take your post as being a dick, just frustrated that people I talked to about this that are supposed to know what they are talking about are full of BS.
The easy to remedy part is not so easy as this is basically starting over.
I also dont see anything specifying behind head, but how are you going to build bar "a"?
Might be a good time to send a quick email to Tom.
In reply to Robbie :
Bar A is a bent tube same size as roll bar to extend behind seat. Then we planned on bracing it with two down bars to base of main hoop. Again my previous experts said this was fine but as Patrick has pointed out they may not know what they are talking about.
FWIW, NHRA has put their entire rulebook online for the first time ever.
https://nationaldragster.s3.amazonaws.com/Rulebooks/2020_NHRA_Rulebook_11_01/index.html
The reader window is a total PITA, and I still recommend getting yourself a hard copy, but at least these rules aren't a secret anymore
In reply to gumby :
Now that rule says within 6 inches of the rear of the helmet, but is does not say must be behind the helmet. All of the rules I could find only specify how far in front of the roll bar is the maximum safe distance. There is nothing that specifies the other direction.
It still looks like to safely pass tech I will be cutting the bar out and re doing it.
Stampie said:That front flange is the problem. 1/4 inch plate with the 3 bolt pattern and then the standard Nissan 4 bolt pattern on it also?
Sorry been slacking on this idea so I drew this for you.
Solid red holes bolt to the transmission. The open red holes bolt to a standard u joint yoke. Sorry my pot lid apparently wasn't totally dry before I used it to draw a circle.
Fladiver64 said:In reply to gumby :
Now that rule says within 6 inches of the rear of the helmet, but is does not say must be behind the helmet. All of the rules I could find only specify how far in front of the roll bar is the maximum safe distance. There is nothing that specifies the other direction.
It still looks like to safely pass tech I will be cutting the bar out and re doing it.
I agree on your reading of the rule, but I'm still going to recommend reaching out to Tom before cutting it all out. Unless you already did that.
In reply to wheels777 :
No worries, corrections will be made.
Maybe I'm missing something but it looks like you have plenty of room to extend the pedal box forward and thus move the seat forward as well. Sure it would mean cutting up your newly done firewall but that's better than redoing the entire cage.
Ok so clearly my assumptions and the advice I was previously given has proven to be incorrect, so a re build will be necessary. Before I go cutting and rebuilding I would like to see if these assumptions will work and/or what other ideas are out there to solve out issues. I think the big issue I was trying to solve is that we have a wide envelope for drivers, I am 6'6" and my partner is about 5' 8" so we need to push the envelope as much as possible.
So first up the main hoop attachment point. I had wanted it at the rocker/rear floor pan junction so it was tied in vertically and horizontally. I can move it rearward about 7" but then it would just be a part of the rear floor. If I make the plate larger say 8x8 do you think that should still be OK.
So if I move the main hoop to this position and lean the bar back 10 degrees. then I think I can get the bar to be right at the back of my helmet when the seat is in the rear most position. What exactly is the rule here? Back of helmet flush with front of roll bar
OR can back of helmet be flush with back of bar?
This sounds like a small thing but it does make an 1.75" difference and adds that to the acceptable range of drivers so it is important.
Here is me in the seat with the seat all the way back, bar leaned back 10 degrees. The aluminum tube is about the height of the roll bar and the back of my helmet is just about at the front of the roll bar. Kurt is not hear to test the forward position but I think it will exceed the 6" rule, so I may have to tilt the bar a bit more vertical and live with my seating position being further forward. Not like I haven't been squeezed into a car before.
Next issue I see is the rear bars, with the main hoop that far rearward the bar angle will exceed the 30 degree spec. IF I run them down to the pads we welded above the shock towers the angle would be about 42 degrees. If I run the bars back further, like the square tube I have in the picture, can I put a 15 or 20 degree bend in it to clear the shock tower and get my angle down?
Lastly can I section the existing door bars and extend them with a sleeve or do I just need to cut them off and start over. Looking at it, it may be easier to just cut them off and re-do but thought I would ask in case.
In reply to AxeHealey :
Yes that is a possibility, not sure I can get enough space as part of that area needs to be removed for front tire clearance. Neither project is going to be fun, and either will require taking out a bunch of stuff we had already finished. I am sure we will look at both projects in detail before we take out the saws all.
Patrick, Wheels77, Gumby, AxeHealey and Robbie, Thanks for offering solutions and help, hopefully plan b will work out.
In addition to Andrew's fantastic list, I would submit an option of fabricating some removable floor mount pedals with simple linkage attachment to the originals, rather than attempting to make the pedal set(and everything connected to it) adjustable.
In reply to wheels777 :
1. Yes first on list, from my above drawing can back of helmet be even with front of bar or rear of bar? This is a 1.75" difference so every little bit helps.
2. We currently have 5" of adjustability
3. I like gumby's suggestion of making a floor mount extension set for shorter driver, that can be easily bolted in.
4. I did not know until yesterday what the lever at the top of our corvette steering colum did, it is a lock for a telescopic column. So there is about 3 " of travel avalible. We did not know about it but now we will paln on making the most use of that feature.
5 and 6 good points we can work on once the engineering is set.
Thanks for your feed back.
In reply to gumby :
I like the idea of a removable floor mount pedal set , I was looking at what it was going to take to make adjustable pedals and not liking the solutions I was coming up with.
So I think that will let me bend the rear stay around the shock tower and keep the angle acceptable.
Thank for the input on the door bars, I still have to decide but it may end up being easier to just install new bars rather than bending and sleeving. I am going to have to put at least some new material in since the main hoop will move back.
I am not good at drawing to scale but could I do this:
Main hoop moved back and leaned rearward 10 degrees.
Rear bars with a bend to go around wheel housings. The dash lines show the original rear bars which would now be at a 42 degree angle.
The dashed line is about where the original door bar was and we attached the dash bar to it, so my thought was maybe bend the new door bar to come down and intersect the old one then weld them together.
Thanks again for the help
OK so yesterday was roll bar repair day, First cut everything out, no fun going backwards.
Then we plated the new area to mount the roll bar, Plate was a bit larger than required and we added a plate going up the wheel well to add strength in a different direction.
Next we welded in the main hoop in the new position ( forgot to take a picture). This location is laid back 10 degrees, with me in the seat my helmet is just in front of the roll bar at a natural seating position. With Kurt in the seat his head is at 5.5" from the roll bar and we will not have to make any changes to the pedal box.
Next was bending some tubing to match the new roll bar position to the existing door bars. Angle was 33 degrees, over bending 3 degrees put it right on when it relaxed. The air over hydraulic jack is a great upgrade to the tubing bender!
We made up an insert repair with some 1.5 in tubing 6" long for that area to joint the new pipe to existing.
After welding and cooling , since we are such master craftsmen both sides
.
Had to take a picture of that because it is likely to never happen again. Final result below, we have not added the back bars because we are changing some things at the back end because of the roll bar change so we will have some other fabrication to do first. Overall we are very happy with the result.
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