Landracing Forum
Tech Information => Technical Discussion => Topic started by: edweldon on February 09, 2012, 01:35:43 AM
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My current project involves a 170" wb lakester chassis too long to easily get in and out of my small shop. I'd like to do it in 3 sections ("bolted together") the center of which is a cage structure pretty close to figure 4B on page 27 of the 2011 rule book. My question is how to best make the connections to the nose section and the rear section (with motor and drive train). Both sections have similar 4 tube rectangular layout as the cage. All work in mild steel; 1-3/4" dia cage tubing. Est'd car weight 1800 lbs dry.
Should I design my own connectors for each of the tube intersections (external tube sleeves with cross bolts) This doesn't thrill me.
How about the weld-on machined steel roll cage connectors that the off road folks use?
I could make it more elaborate with additional bolts, plates and cross bracing in the two end sections where they connect.
Who has done this before besides Al Teague? Legend has it that his liner frame was in two sections; so it would fit in his garage. True? Anyone know how Al did his?
Ed Weldon
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I forget the team but the LONG yellow lakester is done the same way. Pictures are on Sumners site.
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Who has done this before besides Al Teague? Legend has it that his liner frame was in two sections; so it would fit in his garage. True? Anyone know how Al did his?
Ed Weldon
I'm thinkin there's a bloke in the backblocks of Idaho who'll pipe up soon with the answer.... :wink:
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Ed,
I have used the Camberg clamps on two pickups to allow the bed to be removed. I machined sleeves to go over the clamps for strength.
http://www.camburg.com/products/fabrication/billet-tube-clamps/
If you have any questions, give me a call. 302.378.3013
Joe
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At Mountain States we have discussed this at length... no pun intended... Talking about building a stream-lakester-liner... there have been several cars over the years that have been built in sections. We decided that the best idea was machined steel plate bulkheads, much like a lot of airplanes are built but using steel. Our plan was like yours, a front section, a safety section and a powertrain section. Depending on what power you are planning, you may want your lakester to weigh more, so the 1/2 inch plate bulkheads would help balance the weight distribution. We were going to pass the tubes through the plate weld flush on the mating sides and gusset for strength. We planned mating dowels and a ring of bolts to hold it all together....
No, we never put it all on paper, but I remember this being our last version of beergineering this idea.
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Al had to take off the body nose piece and the rear body panels. There was a tubular tail, body support, push bar section that bolted to the frame at the trans-axle area that had to be removed also. After it was in and on stands, the left rear wheel and tire had to be removed to give enough room to walk between the car and his parts storage room. The nose was against the grinder stand next to the big door and the right rear was next to the wall. If he needed to use the lathe, welder, etc, he had to move the body panels outside and climb over the car to get to the machines.
PURE dedication and desire built that car.
Ron
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If you do this it is also worth while to consider designing those segments as break away segments in case of a crash.
This has also been done to give the structure a "safe" place to fail in a serious accident.
My understanding is that the Burland 411 car was designed that way.
Larry
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Hey Ed, You might want to check out the "Frightliner" it was built in pieces, 2 or 3 and it was assembled at the race track. The car also had 4 tires in the back, ran a "Chizzeler Motor, but was cut across , I think either 2 or 4 cylinders with a 4:71 blower. I think Dan Warner may have good info on it, I think owner and Mr. Warner live in the same neck of the woods. I also would like to comment on the break away chassis you mentioned.. First I know I am a "Charter Member" in the "Peanut Gallery", but after looking at Chassis design of Streamliners and Lakesters I can count on one hand the number of cars having run a breakway roll cage. To me that design is the only way to go. All the front engine "diggers" back in the day were built that way... There is flim of Jim Nickles and the Snake racing in early 70s Nickles clutch let go car broke at the breakaway and went by the snake, who thought Nickles was killed, Nickles walked away .. Tony Shumacher had that really bad wreck where the car broke in 3 pieces, and the drivers compartment flipped and rolled at least 6 or 8 times, minimum damage to Shumacher.. Just think about all that energy, in a nose first, wreck being transfered all the way through the chassis.. there is no place for the impact to go except through the chassis and then to the drivers cage..and then really bad things happen... Sorry, I didn't mean to hijack this thread, BUT this subject has never been discussed before on landracing to my knowledge.... Mike R.
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Joe Timney - Good data point on the use of Camberg clamps. Sleeves, especially on the joint between the middle and back frames for my project, sound like a good idea.
Stainless - Your plate bulkhead thoughts are interesting. On my project they are more applicable to the front nose to cage connection than the rear. I'd go with thinner plate to keep the weight down with the idea that if weight there were called for a middle part of the "sandwich" of a larger thickness could be added later,
Ron - Thanks for the confirmation of the Al Teague story. That's worth further pursuit on my part to illuminate the details of how he did it.
hotrod and pookie - The idea of a breakaway driver's safety pod is a good one in general. It crossed my mind. But the problem is how to design the connections for a specific application. Kinda overwhelms me and my particular resources, which are somewhat limited. I'm a retired mechanical engineer. In my career some of my best learning was about what you can't do. In my retired situation I could never muster the design, computational and test resources to attack this problem the right way.
All - thanks for your comments. At this point I like the bulkhead idea for the front connection and the Camberg clamps with reinforcement sleeves for the rear connection. But I'd sure like to hear more about the "nuts and bolts" details of these and other approaches, especially ones that have actually been built.
Ed Weldon
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Here is the flange rings I machined for my streamliner. The frame rail tubing has an inner tube welded to one side. Planning on doing a bulkhead between the flanges. It would allow me the take off the back end behind the drivers pod.
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Ed, I looked but could not find the shots of the 3 piece car. Long yellow Cigar shaped A or AA lakester. There are some good shots of the frame and bulkheads here on the board somewhere.
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Yellow Fatboyz car in reply #760
http://www.landracing.com/forum/index.php/topic,7465.msg133747.html#msg133747
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Ed, the sandwich bulkhead Joe is using is a way you should think about... the bulkhead could also be a firewall.
Our plan the weight of the rear bulkhead was about 160 lbs for the 2 pieces. You could reduce to 3/8 plate and cut 40 lbs, we were looking at about 4 square feet per piece. Be careful building light, on the salt weight is traction
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Joe and Stainless -- Thanks again, guys, for your suggestions. I like the flanges with an inside tube to give a male-female fit. I think I'd give that fit just a bit less diametral clearance than in the bolt holes. Maybe .030". In the flanges for the horizontal rails I'll go with 6 bolts; so that for any heavy moment direction at least two bolts will be in tension. In the back that will be on the lower two horizontal rails only.
The upper tubes are at about a 45 deg angle. Since it won't assemble with a rigid male to female joint like the other 6 I'll go with a short rabbet fit between the two flanges and an 8 bolt circle. This is all nice easy lathe work and rotary table work on the mill and will throw a $250 bonus into the build budget vs. the Camberg cage connectors.
OK, what's this about the 45 degree angle on the two tubes? Well, in the interest of full disclosure, I'm working with a car that's already built. Just needs a new roll cage to meet tech requirements.
I ended up buying Doug King's old Gold Digger Lakester. I don't want to muck too much with an existing design that worked well up to 185 with the Ardun. I intend to stay with the flathead/Ardun and see how far I can take it. 200 or 225 is about as far as I think my budget can take me with that formula. It came with a wing, although that's not the most efficient way to get down force. There is plenty of room in there to add lead or a steel rear belly pan if I need it. There are other factors in my particular program that favor keeping the weight down. But that's another topic.
Ed Weldon
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My current project involves a 170" wb lakester chassis too long to easily get in and out of my small shop. I'd like to do it in 3 sections ("bolted together") the center of which is a cage structure pretty close to figure 4B on page 27 of the 2011 rule book. My question is how to best make the connections to the nose section and the rear section (with motor and drive train). Both sections have similar 4 tube rectangular layout as the cage. All work in mild steel; 1-3/4" dia cage tubing. Est'd car weight 1800 lbs dry.
Should I design my own connectors for each of the tube intersections (external tube sleeves with cross bolts) This doesn't thrill me.
How about the weld-on machined steel roll cage connectors that the off road folks use?
I could make it more elaborate with additional bolts, plates and cross bracing in the two end sections where they connect.
Who has done this before besides Al Teague? Legend has it that his liner frame was in two sections; so it would fit in his garage. True? Anyone know how Al did his?
Ed Weldon
Some images in this post from 2007. ( http://www.landracing.com/forum/index.php/topic,2629.msg31129.html#msg31129 )
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Thanks, I looked all over for that thread and wanted to read it myself!
My current project involves a 170" wb lakester chassis too long to easily get in and out of my small shop. I'd like to do it in 3 sections ("bolted together") the center of which is a cage structure pretty close to figure 4B on page 27 of the 2011 rule book. My question is how to best make the connections to the nose section and the rear section (with motor and drive train). Both sections have similar 4 tube rectangular layout as the cage. All work in mild steel; 1-3/4" dia cage tubing. Est'd car weight 1800 lbs dry.
Should I design my own connectors for each of the tube intersections (external tube sleeves with cross bolts) This doesn't thrill me.
How about the weld-on machined steel roll cage connectors that the off road folks use?
I could make it more elaborate with additional bolts, plates and cross bracing in the two end sections where they connect.
Who has done this before besides Al Teague? Legend has it that his liner frame was in two sections; so it would fit in his garage. True? Anyone know how Al did his?
Ed Weldon
Some images in this post from 2007. ( http://www.landracing.com/forum/index.php/topic,2629.msg31129.html#msg31129 )
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old gringo -- Much appreciate your finding that lakester thread. It has some very instructive photos showing structural details. Bolts through reinforced sections of the tubes to bring the two halves together looks interesting. It does put a lot of loading on two bolts. But the calculation the stresses in the bolts is pretty straightforward.
I think I would make sure the contact surfaces were in a good single plane when assembled. A 24" x 24" piece of MIC 6 aluminum jig plate or a similar scrap of countertop granite and feeler gauges would work. I'd shoot for 20-30 mils flatness across each side of the joint and maybe add stainless steel (for salt resistance) shims at selected points to make that up. Then I'd carefully torque up each bolt-nut combination using a micrometer to measure bolt stress. That way the bolt preload takes away the effect of fatigue on the bolts. (much the same way as cylinder head bolts work). Nice thing in this case is that the ability to measure bolt length easily gives a good preventative maintenance check point on the bolted joint.
Here's one of the pics from that thread showing the features I'm referring to:
(http://www.landracing.com/forum/index.php?action=dlattach;topic=2629.0;attach=1243;image)
An interesting question in the analysis of this design is what G forces would the frame see during normal operation over the Bonneville surface at speed. Really it's about what frequency and what G levels would cause the driver to think "this thing is shaking too much" and lift his foot. ............... Ed Weldon
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After looking at some old pictures, when Al changed from lakester to streamliner, he did make the front end to come apart. I don't think he ever had it apart after and it wasn't necessary other than as described, to get it into the garage.
Ron
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Ed,
If your chassis is a basic 4 tubes in a square/rectangular pattern wouldn't it really be easier to machine some accurate clevis connections with a 5/8 inch dia reamed hole and use 5/8 inch shoulder bolts? If you make the clevis parts accurate and ream the holes for a good slip fit. The bolts are then in double shear and if you use a 5/8 dia they would have a double shear strength of around 50,000 lbs ( using a conservative sheer strength of 50% of the tensile strength of 160,000 psi). This would be the equal to a distributed load on your 1-3/4 x .120 wall tubing of about 33,000 psi tension load which is slightly less than the yield strength of mild steel tubing (assuming 36,000 psi yield strength). Now you have a joint that is very easy to build and very easy to align and assemble plus very simple to fabricate. If you made the clevis pin 3/4 inch the strength would be approx 70,000 lbs and the tube stress would be approx 46,000 psi which is above the material yield strength.
I saw a nostalgia fuel dragster built by Sterling that was done this way, it was split just in front of the motor. They brought the car to the strip in two parts in a small Ford pickup, the engine, rear end, tires and cage were rolled onto the pickup bed and the front section, with the fuel tank, front axle, wheels etc were on the lumber rack. Took them about 15 minutes to bolt the thing together and run.
I don't especially care for the way the old gringo chassis is done as the load paths from the connection bolts to the main structure put the bulk head rings in bending, if you do it this way I would highly recommend additional gussets or diagonal tubing that goes from the bolted joint to the main longitudinal structure. The little gussets that they have at the corners are nothing but welding practice, they have minimal affect on the strength of the structure. The larger square tube gussets do contribute to the structure's strength and stiffness but they should extend closer to the bolted connection. (In my opinion. Which with a buck fifty you can get a small cup of coffee at Starbucks!)
Rex
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Rex, those small gussets appear to have threaded holes in them and are actually mounting tabs.
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Ed
PM sent.
I do agree with Rex that the bolted connections in this particular application are in the middle of the tube causing rather large bending loads in the bulkhead tubes. Hopefully the tubes are of sufficient wall thickness to allow for this The saving grace in a design like this is any failure is probably going to be rather slow and should be noticeable long before catastrophe occurred.
Pete
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Pete - Got your off list email. More comments after I get rid of the family birthday event later this evening.
Reference "I do agree with Rex that the bolted connections in this particular application are in the middle of the tube causing rather large bending loads in the bulkhead tubes." I don't like that exposure to bending of the frame tubes either. But they'll get the first indication of problems likely when the belly pan starts scraping the high point of the trailer when they are loading it. "Failsafe" would be when when it sags enough that the belly pan actually drags on the salt. ............. Ed Weldon
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The bolt on front section of Al's chassis (Betsy) was originally done that way because Al wasn't sure how stable the staggered set up would be. The plan was, if it didn't work out he could go back to the lakester front end & not miss a season.
We did take it appart one time back in the 90's to repair the damage after the front tire explosion episode. 97 I think.
The 5/8 Allen bolts came from the back & screwed into welded bungs in the horizontal tubes of the front section then there was two more 1/2" Allens in the top & in the bottom. The heads of the Allen bolts were beside the horizontals on the rear section with gussets & diagonals in the frame as well.
When the nose bit the ground back then at 380-ish, none of the bolt up show'd any adverse affect. It was just easier to take it off to repair the damage on the bottom & we gave it a fresh set of bolts.
Betsy was a tough ol girl.
Sid.
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Rex - You've got some interesting comments about relative stresses and the two piece dragster description. Again, excellent data points. But I'm not too enthusiastic about close fitting clevises. I expect to take this thing apart several times. Some movement or welding stress relief in the frame could turn an effort of taking apart into a pain and putting back together into a crying session.
I don't like the placement of bolts away from the fairly ridged tube connections on the #575AGL either.
http://www.landracing.com/forum/index.php/topic,2629.msg31129.html#msg31129
I think I could use their approach or something similar on my project and put the connections closer to the corner tube intersections. So their setup has me thinking.
Thank you for your comments and you engineering based numbers on relative stresses and proportions.
This is one of those situations in engineering where one component, in this case 1-3/4" dia 1/8" wall mild steel tubing has a long and valid experience set supporting it (and a codified rule as well). Other pieces of this structural "chain" are well selected to be stronger "links" than the tubing. But some elegance in the design is desirable. This means that the strength of these new components like nuts and bolts ought to be "better" than the tubing; but not so much so as to add parasitic load (cost is also a "load") that adds no real value to the design. ............................. Ed
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Sid (kiwi belly tank) - Thanks for the info on Al Teague's car. If I understand you description correctly Al's frame had different spacing on the horizontal tubes between the two sections such that a bolt could be driven through a cross tube close to the joint and into an insert in the end of the tube in the frame other section. This sounds neat but isn't so great for me since it I'd just as well prefer not to change the existing frame width between the sections due to the existance of some very nice aluminum body work that would have to change if the frame were widened and the very real concern with narrowing a proven design. The one exception to this line of thinking is in the rear section where I may choose to push the rear section frame rails out a bit to ease maintenance on the engine and transmission, especially the stock Ford flathead starter which is a bear to remove and the possibility of eventually goinf to a dry sump system that could use the space.
With all the talk in the abstract I think it would be helpful to post a picture of the car as it was running about 20 years ago. Trouble is I haven't yet figured out how to insert or attach a .jpg file from my own computer. ............ Ed
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Hmmmmmmmmmm ...... That didn't show up in the preview. But I see it attached... OK, now I know how it works. Ed
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Ed, thanks for bringin this thread up. My front and rear suspension will be using similar "pods" that also hold the bodywork, chute tubes etc. as well as the axles. All this discussion is helping me finalize some ideas on how to do it.
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Ed,
To not re-engineer your wheel so to speak, if you just run some diagonals out from the bolt location to the opposite corners, that'll triangulate it & stiffen that baby right up. Smaller tube will do the job.
Sid.
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Sid - There are a couple of places where diagonals may be the right answer. Certainly an option if a connection point has to be away from a frame corner joint.
Right now the frame with some sheet metal components is still sitting out in the rain. Won't hurt it any since it is all powder coated. But weather conditions are not particularly inviting for working out there and taking closeup photos, which I now know how to post. Later this week, I think...........Ed
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Too bad about the powder coating Ed. I don't like the process simply because it makes repairs and modifications difficult. That being said I definitely use it when I know there aren't going to be any modifications to the project I'm building. No race car falls in that category.
Be sure you get the areas where you're going to be welded sand blasted well back from the area where you're going to work. That's probably about twice as far as you think. The powder or the plastic coating melts at about 450 deg. F if I remember correctly and will surely run back to where you're working, so don't let the parts still coated get that hot. The good thing about the coating is that if you're planning on using the same color you don't have to remove all the coating as the old stuff will just remelt and blend with the new.
Good luck with the mods.
Pete
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Pete - Glad you brought up the powder coat issue. It was somewhere in the dark recesses of my brain; but you saved me from having to recall it in the heat of "battle". (a limp pun).
This prompts some creative thinking about heat fences for round tube. Perfect for filling boring time slots or trying to get to sleep. The latter seldom produces anything more useful than the trip to dream time. Waking up time is much better for that.
Thinking about redoing the coating reminds me that with the frame in sections the actual process logistics get a bit easier. In my case Techshop has a small powder coating oven that I'm sure the nose section will fit in. But the whole issue of powder coating for the new work on this car needs to be revisited. If you want to really get all the salt out of it after a season it really needs to come apart for cleaning. At that point an ordinary paint coat may make more sense. And that illuminates another advantage of the sectional construction approach in that it makes that annual maintenance project a bit easier. .................... Ed
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Pete is right about sand blasting the powder coat off for the best method of welding another method I have used is to grind the coating off and then heat the metal with the "blue wrench" to burn off the coating that is impregnated in the metal and then weld. Either way requires re-coating and sand blasting is the cleanest but sometimes not readily available.
Rex
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Ed,
PM sent.
Ed
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"sand blasting is the cleanest but sometimes not readily available."
I've got a little sand blasting outfit - can be hand-carried (although heavy, it's made of plastic). It hooks to the air from the garage's compressor - 60-gallon tank - and does fine for jobs like I think this one would be. I've had it for years - but it's probably from Grainger - for sure NOT from H.F. If you don't have one in your array of tools it's worth considering. You probably won't use it often, but it's the nuts when you do need a little blasting.
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Try one of these cheapies, ideal for those hard to get spots.
Sid.
http://www.harborfreight.com/gravity-feed-blaster-gun-93221.html