Jerry, Richard may be right, but before you do anything about the welded side plates on the roll bar, I suggest you call Jeremy Thoennes (pronounced like the game "tennis") at SCCA, 800-770-2055). There are a great many formula and sports racer cars that have the roll hoop boxed in like what I see in your photos, and the club may consider that legal and desirable. Stan
Stan Clayton
Stohr Cars
Stan,
I'll call tomorrow to check on that. Also the old Merloy DSR had the same design roll hoop. That is where I got the idea.
Not sure how I deleted the other pics. If someone can tell me what happend I would appreciate it. I tried to clean the upload window and lost all the other pics.
Jerry,
The panels welded to the roll bar braces was ok on the Merloy because in DSR there are no restrictions on stress bearing panels.The way the F1000 rules are at the present time the only panels that are allowed to be stress bearing are the floor pan,the front bulkhead,the dash hoop bulkhead and the roll hoop bulkhead.Also if you don't have forward facing roll hoop braces you will have to submit it for approval as an alternate design by an engineer.The Merloy you copied was an approved alternate design.
John
I can argue that Jerry's side panel welding of the rollhoop is legal:
1) The Van Diemen FC's use the same concept - FC has the same non-stress bearing panel rules.
2) There is only one continuous weld on each side. So the welds cannot ever be less than 6" apart. To obtain a distance, you must have two points. In this case, there is only one.
So I agree with Stan for Jerry to call Mr "Tennis". And I would never protest this. At the track, if I thought it might be unsafe, I would carefully tell him.
IF the welds were continuous around the full perimeter of each plate, then I would tend to agree - I've put forth the arguement before that if one had weld "tacks" that were 6" long, separated by .1", they would be perfectly legal because the centers ( the measurement point specified in the rule) would be more than 6" apart. Also if they were brazed in place, the rule has been circumvented because it doesn't specify brazing!
From a safety standpoint, my opinion is that this sort of boxing in of the hoop should be legal.
For some reason I cannot open up the new pictures.
I can't open any of the pictures and I feel all left out!
Brian
pictures changed somehow?
the pictures used to display, but do not show up now. an error message is displayed instead when an attempt to open them is made.
glad I'm not the only one with this problem.
Jerry said he accidentally deleted some of the pictures.Originally Posted by rickjohnson356
Scott Woodruff
83 RT5 Ralt/Scooteria Suzuki Formula S
(former) F440/F5/FF/FC/FA
65 FFR Cobra Roadster 4.6 DOHC
To everyone,
First thing is that I'm trying to get the pictures back up. I don't know what happened. It seems like you can only post so many pics and then you run out of memory or something. When I tried to clean up some space the pics disappeared.It took five years to figure out how to get pics to post and now there gone again. I was starting to get some good feedback and now this. Sorry.
Now, about the roll hoop. I called Jeremy at SCCA today and he said that the side plates were legal. He didn't say anything about them being welded solid or skip welded. Only problem is that the support tubes run back instead of forward. Haven't heard from John Bauer at homologation about this. I may have to get a finite element analysis done or add tubes going forward. If someone can give me some information on this analysis it would be great. Ten dollars of tubing and 30 minutes in the shop will probably be the way the problem gets solved but I would rather not scrap the body and change the way the car looks if the analysis is not to time consuming or expensive.
It would be interesting to hear just what rule ( or interpretation) Jeremy based his opinon on to justify the side plates!
Jerry:
Don't for a second make the common mistake that Jeremy's opinion carries any weight if a protest ever came up. The only people who's word is final on the interpretation of any rule is the Court of Appeals. Everyone elses opinions are just that : Opinions!
I had hesitated to bring up the braces as I wasn't exactly sure what I was seeing in the picture. If indeed the vertical hoop is the main hoop ( and passes all of the other criteria to be declared the main hoop - GCR 9.4.1, and GCR 9.4.5), then you will need to add in forward braces. Sorry!
However, if you can get a registered engineer to do an FEA study to show that it passes the alternative structure requirements ( GCR 9.4.5.E), then you can forget about forward braces. Unless you have friend willing to take on that responsibility, this route can get expensive!
The VD's etc, that have the hoops paneled, and no forward braces ( is this really so? I haven't bothered to really look at the newer VDs in quite a while!), in my opinion could only be legal if the either went the alternative construction verification route, or where FIA certified the design ( which I have heard many times is a legal alternative, but have as yet been unable to find the rule that actually states that!).
However, I would still question the use of these sorts of stressed panels in an "alternative" design, since the rules expressly forbid the use of stressed panels everywhere except the bulkheads and floor. While it might possibly be a perfectly valid arguement that such stressed panels are an integral part of such an alternate design, I would personally hesitate to just blindly believe that the rest of the Club would see it the same way!
Good luck!
Last edited by R. Pare; 07.13.07 at 10:06 PM.
R Pare,
I can't tell you how Jeremy came to his decission on the plates. You'll have to ask him. Not sure how there is no person to tell you an exact definition of a rule. I personaly think there is to much gray areas in the SCCA rules. The NHRA had definite rules and that was that.
I have already talked to an engineer about doing an analysis on the chassis. I think it will be reasonable. If the structure doesn't pass I'll just add the forward bars.
I would still like to know if you meant 700-800 pounds on each spring or a pair of springs because I can't find any springs over 450 pounds. I'm using old koni shocks with a long spring. 12 inches I think. I'll have to measure again to be sure.
Jerry:
I just edited in some more stuff in my last post while you were replying!
Springs: Yes, that was per corner. You can find the necessary rates in shorter lengths, no problem. In the rates we all normally use, 4" springs are all that is necessary.
A rule interpretation CAN be had by paying the Club $250 to go thru the process. Outside of that, the only way to get a ruling is through the protest system (ending in the Court of Appeals), but even then that ruling is only valid for THAT car for THAT event, and expires at the end of the calendar year unless added to the GCR. The CoA ruling CAN be used to help determine the outcome for any subsequent like protests for that same or other cars (true in the initial protest portion, but you should expect that the CoA would make the same ruling again if the protest gets that far), but will only become a real rule if the BoD enacts a change in the GCR.
Yes, the rules can be a bit vague in this club! But, being able to adjust your thought process as technology changes is half the fun!
PS; Is your main hoop the minimum 1 3/8" that is required? Hard to tell in the picture.
The main hoop is 1 3/8 o.d. x .120 wall. I'll have to recheck the wall thickness but that is what I was told when I bought it from Matt when I bought it.
Any progress on uploading the pics? This sounds like a good thread but...pictures...thousand words...yada yada..
thx
Pics are back
I finally got most of the pictures back up.I can't get the rest of them on here because it says I've used up my quota space. And I won't be able to put more on but these sould me good enough to show the best parts to critique. If you want to e-mail me about something send it to 1012noemi@msn.com but I would rather keep it an open discussion on this forum. If you want more pics I'll have to start a new thread or e-mail them to you.
Thanks for the input.
Jerry-
Here's how to post more images:
1) Go to www.imagershack.com Click on "Image Hosting", then click on "Free Image Host".
2) Click the browse button to find the image on your computer and open it.
3) Then click "Host Image" - it will upload the image and give you a link to it.
4) Copy (highlight it and hit the ctrl key and C at the same time) the code in the "Link for forums format #1" and paste (highlight it and hit the ctrl key and V at the same time) it into the apexspeed message window. It will create a thumbnail image like the one below.
When someone clicks on the thumbnail it opens up another window that has the picture.
(Sorry if some of that is obvious, just wanted to make sure you knew all the tricks)
Billy Wight
Luxon Engineering
www.luxonengineering.com
858.699.5313 (mobile)
billy@luxonengineering.com
Thanks Billy,
You have an e-mail I just sent.
Testing...testing....one...two...three...is this mic working?
I have been playing with MySCCA.com to see if I can directly link to photos posted there. To test this I simply opened the public photos albums (don't you know...they are all "cool"...
If this works, you should see a Ralt FA.
MySCCA.com is an officially licensed SCCA site, so posting up your photos and videos supports the club and gets around those pesky monthly bandwidth limits (talk about LAME excuses...)
Anyway, I hope it works.
Stan Clayton
Stohr Cars
Jerry;
What is the radius of the main hoop at the top ( centerline radius)? It has to be 3X the tube diameter ( or a minimum of 4.125 radius) to meet the basic specs (GCR 9.4.1.G). If it is not that radius (or larger), it has to be certified under the "alternative structure" rule. Also, does the hoop meet the chassis at at least a 15" (inside walls) width at some point? Again, if not, it will have to go the alternative route.
R Pare,
The roll hoop is 1 3/8 o.d. x .120 wall. It has a 5" centerline radius (maybe 5.25 depending on where it is measured) and it meets the bottom main frame rails at 19.25" inside measurement. It should be ok. The only thing I was worried about when I built the car was the forward braces. I tried to read the rules 6-7 times before I started the project and kept the rule book close through the whole process. But with what I call floating rules it's hard to know if your doing the right thing.
Good!
Looks like the only part that will bite you 9make you go the alternative route) is the braces, and possibly the panels.
example of welded rollbar gussets
Hate to dispute Richard's comments, but there is a history of situations where this approach has been approved, therefore, based on precedent, the (large) gussets should be ok.
I have attached a picture of the rollbar portion of my C-71F, a 1991 car homologated in 1993. I have had no poblems with annual techs or at the many races we did last year.
--------------------------------------------------------------------------------------------------
Richard: I called then 'gussets' for lack of a better term when I was writing the post. Don't really know the correct term for these or similar panels. There was one entry in the logbook regarding the RB, but right under it was a higher-up Chief Tech signature and date saying it was approved. I will check the entry and the specific GCR section it referred to again to be sure.
I've got enough worms for right now, no need to open any new ones.
Last edited by rickjohnson356; 03.24.08 at 2:54 AM.
Very possible that you never will get teched on that issue, but don't make the common mistake of thinking for a minute that just because the car passed Homologation that it automatically means that these panels are legal - it only means that no one has picked up on them as yet, or don't care enough to put it to the test by protesting. If someone protests them, you could very well lose if their arguement is good.
IF however, the bar design was approved through the "alternative structures" process, then I would agree that it most assuredly is legal - and from what I can see in that picture (admittedly not enough to make an authoritative statement), the only way that structure is legal is by that process.
While it might be tempting to call the panels "gussets", if Tech accepts that arguement as valid, then they would have no choice then to declare legal any full-welded-in panel anywhere in the chassis - after all, "gussets" are highly recommended!
I'm not sure that you would want to open than can of worms !
now that I can see the pictures, this is a really fun thread! My comment is that the front lower wishbones have a rod end loaded with the suspension weight in bending. I like to use a spherical joint pressed into a housing there, but it does look like a hefty rod end.
I always wondered how the VD's et al got away without forward roll hoop braces, actually, has anyone actually answered that yet?
Brian
Jerry;
Brian's mentioning the front rod ends made me go look at them again. He's right - they may be a bit over-stressed , especially the lowers ( the uppers should be fine). We've seen 1/2" high strength rod ends bend the shanks under braking on FF's if there is too much exposed shank, and the problem is even worse on FC's. You have to remember that the lower rod end is not only taking those same braking torque loads, buy also the car weight, PLUS cornering and bump loads. I'd suggest strongly that you use a 5/8" rod end at the least, and get the nut out as close to the head as possible to keep the unsupported shank as short as possible.
Also, beef up the mounting tabs for the pushrod by lengthening the base where it welds to the arm, and add a washer to each side.
Rick,
The plates were said to be legal but if someone wants to protest them I will get a die grinder and cut them off. For now they stay.
R. Pare and Brian,
The VD rearward braces were probably sent in as an alternate structure. As for the plates on the sides they may get away with them because the hoop is bolted on with the bolts farther apart then 6". I still think this is VERY weak. I don't want a bolted on roll hoop on my go kart.
The rod ends on the bottom and top a-arms are 3/4 chrome moly. Like I said before I tend to overdo things till I know what I can get away with. I figured If they worked on a 4-link suspension on a high torque drag rear end they would hold the loads I was going to put them under. Also there are only 2 threads showing past the jamb nut. I'll design the next set of bottom a-arms with the spherical bearings you are talking about. I did it like this to get more adjustment. Maybe they will hold up.
Not exactly sure what you mean about the push rod tabs. Could you elaborate a little more please?
I found 650lb. springs that will work and I can tighten them up to get the pressure I want. One problem solved.
I'm working on cutting down the Porche 914 rack and pinion and tapping it so I can turn the rod ends and make straight steering tubes out of aluminum. They will also move the bolt up point very close to the attachment point of the a-arms to get the bump steer better. After some work I should have another problem solved.
Once I figure out the ackerman point I'll change the spindle arms and solve another problem.
I'm still trying to figure out the rear suspionsion.
My biggest problem right now is getting the roll hoop passed. We'll see how that goes. I can save the bodywork by making the forward bars bolt in which is what I would have to do anyway to get the fuel cell container in the car. According to the rules this is legal if you do it the right way.
Jerry
Jerry:
The push rod tabs - the welded-on sheet stock that the pushrod bolts to on the lower arm - are rather short length-wise. To keep all of the weld in compression, you want the outboard end to go at least to the line described by the centerline of the pushrod - otherwise, the outboard end of the weld acts as a pivot point, causing the stresses on the inboard end of the tab to be upwards - ie - the tab is in tension at the inboard end.
Bolted hoops can do the job very nicely - how do you think they are attached to Indy car and F1 monocoques? As with anything, the design has to be right.
The upper arm outer rod ends can be 1/2" alloy, as long as the overhang is kept to a minimum. No need to carry the extra weight. The inboard ends can be 5/16" mild. The lower arm inner rod ends can be 3/8" alloy.
Most likely no one will ever bother to question the side panels - it ain't worth it unless you are spanking their butts on the track!
Hopefully the picture will post.
I have new steering and anti-intrusion bars started.
I machined the Porche 914 steering rack and made it where the
steering arms are straight. I also made the bolt center on the rack
and the a-arm alot closer. I went from 4 3/8" c/c to 7/8" c/c.
I've still got to figure the ackerman point and make the arms
on the spindle correct.
The top anti-intrusion bars are 1/2" o.d. tube with 3/8" i.d.
telescoping tube inside. The stohr has 3/8" welded solid but
I believe the VD cars use the telescoping tubes also. The push
rods clear so I think I'm o.k.
Great progress!
Steering arm help
Well, the car is homologated and I'm trying to get ready for the ARRC.
I did have to do a finite element analysis and alternate design submission.
The roll hoop was 2.2 times stronger than the SCCA legal front brace design
so I feel pretty good about that. Only problem is I slowed my work waiting for
homologation and I'm behind as usual. Billy Wight at Luxon engineering
did the analysis for me and was great to work with so if anybody else needs
help please give him a call. 858-699-5313. When I get some time I'll post
pics of the updates that alot of people suggested.
Now to the question I had. What is the distance from the top a-arm mounting
stud to the steering rod bolt C/C on the upright? If someone has a picture of
the front VD upright and steering arm I would appreciate a close up.
Thanks,
Jerry
Jerry, 2
Single rear brake
Yes indeed. I note that BRM used this on the P25 back in the 1950s and never cured these problems. I'll see if I can find pics somewhere in the library.
Having said that, I love the "everything old is new again" thinking. Right up my alley
I agree with the dual rear outboard brakes but this is all I have right now and it will have to work for awhile.
I hope the pics post. If they do it's pics of the different tabs on the a-arms to spread the loads on the welds. There should also be one of the bellypan rivits. I have round bottom tubes and I added a fully welded flat strip to the rails for better bonding. I highly recommend this if you build a car with round bottom frame rails. I also added rivits to the round tubing also to try to keep from rolling the sheet metal when I do some agricultural work.The last pic is of the front springs, bell cranks, anti-intrusion bars, and the pushrod mounting holes. I finally found some 800# springs to fit my old shocks. I added a thin plate to the bell cranks to give some support. I also moved the pushrod bolt hole in to stiffen the car up. I figure I can put them in the outside holes in the rain and soften it up. Not sure how that will work but I'll try it and see one day. More updates as it gets assembled. I do drag car chassis work on the side and just got an emergency repair job so it may put a halt to the formula car work for the next week or so but I'm still trying to be ready for the ARRC. Got to make racing money first though.
Jerry
New floor pans always look nice, don't they?
I like the rain rocker option. Sounds like a clever solution.
Racer Russ
Palm Coast, FL
Attachment 7032
Well, as usual it took alot longer to assembly everything than expected and the body still needs alot of work, but it ran for the first time today. For the most part everything went very well. I got to go run a parking lot we use for local solo races in Huntsville so I had a big place to run around. Once I figured out the shifter was working in reverse I got the car to take off and make laps. It's hard to find a good engineer.
Now for the only big problem I had. Same problem I had with the old SV. It ran hot after 20 minutes of running at speed. That is a big improvement over the old car though. I know I need to put bigger jets in the carbs to richen it up. Anybody know what jets the DSR guys used. I also will put a bigger radiator in the car. I'm using the motorcycle radiator right now. I have a larger one I'm going to get from JEG'S as soon as possible. I have water wetter in it also to try and help. How much will an oil cooler help the water temp? Does two water radiators help much or is it just more weight without a big improvement?
I went from a small list of things to finish to a big list of things to fix. I love building new cars.
If the weather is still good I'm going to try to run it again next weekend and see if I can make it run for 40 minutes without getting to hot. I'll also try to keep the front end facing the front. I don't have a newer GSXR but this thing was still quick an a blast to drive!!!
Good luck to all those who are converting or building there own cars. It will be worth the work and aggravation when it's done.
Jerry
Jerry, My guess is the bike radiator is your overheating problem. They are just too small. I'm using my original SuperVee radiator in my Ralt & it works fine. It's still not too big though. Keep up the good work, you're doing great.
Scott Woodruff
83 RT5 Ralt/Scooteria Suzuki Formula S
(former) F440/F5/FF/FC/FA
65 FFR Cobra Roadster 4.6 DOHC
Jerry:
Nice to see that you got it up and running!
Couple of observations:
1 - The sharp corners on the nose will set up a ton of turbulence as the air spills off of the edges,. The turbulence off of the bottom-side edges will especially hurt the airflow to the rad inlets.
2 - The rad inlets also need some radiusing to decrease turbulence - I suspect that right now you have so much turbulence in front of the radiator that the flow thru the radiator is being decreased by a substantial margin. What you would like to do is add in an interior duct that leads smoothly to the radiator face - some interior dividers might also help, but the ductwork is an absolute must.
3 - Without the rear bodywork, the air that is trying to exit the back of the sidepod is having to fight the high pressure wake coming off of the front of the rear tires. Expect to have to do a bunch of experimenting there to get it right.
All in all, you've done an impressive job for your first try! Have fun with it!
Another thought:
How fast were you going? I need to be trucking to keep my car cool. If you were just standing on it, but not driving at speed for any amount of time, you were creating a bunch of heat without the airflow.
I'd bet it would go longer on a road course.
Sean O'Connell
1996 RF96 FC
1996 RF96 FB
2004 Mygale SJ04 Zetec
I'm with Sean. On road courses we average 95 to 105 mph. I don't think you can do that in a parking lot. Your setup may cool enough on a road course, but noe getting enough air flow on a parking lot.
I would still do the changes Richard Pare suggested.
Congratulations, Jerry. That's quite an accomplishment. It must've been pretty satisfying to feel it under power.
I was going to respond with my cooling thoughts, but they've all be mentioned above.
A few weeks ago I let my engine run for 5 or so minutes in the driveway and things started getting pretty hot. As a result, I rerouted a few lines and added some heat shields to protect things from the exhaust.
Good luck & see you at the ARRC.
Racer Russ
Palm Coast, FL
There are currently 1 users browsing this thread. (0 members and 1 guests)
Posting Permissions
Reply With Quote
