Welded Steel Uprights

[JamesCH13]

I have had some interest in the welded steel uprights and the auto-pulse welder settings that we are using this year (Cooper Motorsports) so I decided to post some pictures of the uprights and talk a little about auto-pulsing.

Our school has a (one) 3-axis CNC machine that can take about 5000 g-code lines at a time, so we don't have the luxury of "just CNC-ing it". We (and by we I mean me) weld as many of our parts as is practical because it's fast, strong, and cheap. Our suspension guy designed some pretty awesome welded steel uprights. The centers are machined 4240 alloy steel (note the awesome surface finish, bad surface finishes means cracking) and the ends and panels are 4130 alloy steel. The centers and ends are jigged and then the plates are tacked in and seamed. the front uprights weigh 2 lbs, the rear uprights weigh 2.7 lbs.

I welded everything with ER80S-B2 wire with auto-pulse. I also passed my AWS welding exam welding 4130 with ER80S-B2 wire using auto-pulse. It works really well.

Setting a low auto-pulse frequency is good to help beginners develop a pace for dipping and moving, but if you want to reduce the HAZ of your weld without sacrificing penetration and improving how the weld puddle "flows" I recommend a high pulse frequency (I use 22hz) with 50-70% on time and 50-70% background current. I typically set the maximum current on my welder to 123amps with 65%/65% when welding frame stuff with 0.095" wall tubing, 99amps with 50%/50% works well when 0.065" or thinner wall tubing is involved.

With the increased welding speed I found I had with this I was able to bang out the uprights (tacking and seaming) in 8 hours, and I seam welded our entire frame in about 14 hours.

The original article with a video is here:

http://www.weldingtipsandtrick...bing-with-pulse.html (http://www.weldingtipsandtricks.com/tig-welding-4130-chromoly-tubing-with-pulse.html)

http://photos-c.ak.fbcdn.net/photos-ak-snc1/v2618/113/13/28900759/n28900759_30276874_6958439.jpg


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[JamesCH13]

I have had some interest in the welded steel uprights and the auto-pulse welder settings that we are using this year (Cooper Motorsports) so I decided to post some pictures of the uprights and talk a little about auto-pulsing.

Our school has a (one) 3-axis CNC machine that can take about 5000 g-code lines at a time, so we don't have the luxury of "just CNC-ing it". We (and by we I mean me) weld as many of our parts as is practical because it's fast, strong, and cheap. Our suspension guy designed some pretty awesome welded steel uprights. The centers are machined 4240 alloy steel (note the awesome surface finish, bad surface finishes means cracking) and the ends and panels are 4130 alloy steel. The centers and ends are jigged and then the plates are tacked in and seamed. the front uprights weigh 2 lbs, the rear uprights weigh 2.7 lbs.

I welded everything with ER80S-B2 wire with auto-pulse. I also passed my AWS welding exam welding 4130 with ER80S-B2 wire using auto-pulse. It works really well.

Setting a low auto-pulse frequency is good to help beginners develop a pace for dipping and moving, but if you want to reduce the HAZ of your weld without sacrificing penetration and improving how the weld puddle "flows" I recommend a high pulse frequency (I use 22hz) with 50-70% on time and 50-70% background current. I typically set the maximum current on my welder to 123amps with 65%/65% when welding frame stuff with 0.095" wall tubing, 99amps with 50%/50% works well when 0.065" or thinner wall tubing is involved.

With the increased welding speed I found I had with this I was able to bang out the uprights (tacking and seaming) in 8 hours, and I seam welded our entire frame in about 14 hours.

The original article with a video is here:

http://www.weldingtipsandtrick...bing-with-pulse.html (http://www.weldingtipsandtricks.com/tig-welding-4130-chromoly-tubing-with-pulse.html)

http://photos-c.ak.fbcdn.net/photos-ak-snc1/v2618/113/13/28900759/n28900759_30276874_6958439.jpg


http://photos-d.ak.fbcdn.net/photos-ak-snc1/v2618/113/13/28900759/n28900759_30276875_1150384.jpg

http://photos-e.ak.fbcdn.net/photos-ak-snc1/v2618/113/13/28900759/n28900759_30276876_5483236.jpg

http://photos-f.ak.fbcdn.net/photos-ak-snc1/v2618/113/13/28900759/n28900759_30276877_8083113.jpg

http://photos-g.ak.fbcdn.net/photos-ak-snc1/v2618/113/13/28900759/n28900759_30276878_6459688.jpg

http://photos-b.ak.fbcdn.net/photos-ak-snc1/v2618/113/13/28900759/n28900759_30276881_993353.jpg

http://photos-e.ak.fbcdn.net/photos-ak-snc1/v2618/113/13/28900759/n28900759_30276884_1060596.jpg

http://photos-d.ak.fbcdn.net/photos-ak-snc1/v2618/113/13/28900759/n28900759_30276883_8222749.jpg

[J.R.]

Uprights look great! We're finishing ours now, we CNC them. We only have a 3-axis and it worked out fine for us. We run 3 different programs, with a total number of lines nowhere near 5000, so if you want to CNC them next year, you shouldn't really have any problems! Just keep your options open, but the welded ones look great!

[JamesCH13]

This is very true, but with just one old machine at our disposal we can only make so many parts in the time available to us. We have it running as much as we can. We use it to make things like stainless steel brake rotors, jigs, etc. The other problem is that it's in the basement and there is basically no ventilation, so we are not allowed to use coolant or oil on the CNC, making a 2 hour part an 8 hour part. But we do survive.

[rjwoods77]

What wall thickness is the bearing housing? Do you get any kind of warpage from welding on it? What was the reason for using 4240 on the bearing housing. I read you post on that link about post machining after heat treat. Did the shaft and thread for the rod ends change dimensions at all? I know you said you did the bearing bores but what about the fit of the posts to the bearings?

[JamesCH13]

Bearing housing walls were machine down to about 3/16 (ish) and because we expected some warping they will be machined out to 0.125" for a slip-fit to the bearings. The front housing's diameter changed a little bit, about 0.003" on their diameter, the rear bearing housings (larger ones) warped about 0.010" on their diameter. The bearing posts are fine, no measurable warping on those, their orientation also didn't change in any appreciable way.

Lots of tacking and a very good fit-up means little warping. I know the guys notching our frame tubes hated me for demanding excellent fitup, but our whole frame warped 1/32" or so from the rear bulkhead to the front bulk head using very few jigs, and only 2x4s on plywood when we had a jig.

The reason to use 4240 for the housings is that we could get 4240 tubing in dimensions that drastically reduced the amount of machining we had to do.

[Jersey Tom]

Looks pretty good, man. We had a pulse feature on our Miller Syncro 350 (300?) but I always preferred just doing it by pedal... somehow the pulse circuitry was screwy. Instead of the "down" current being say 70% of your pedal current (or set constant current), it always seemed to be a percentage of the MAX MACHINE CURRENT.

On a 350A machine, that was a big surprise the first time I tried doing some thin tube like that...

Then again for me, I was in the opposite scenario. I CNC'd as much crap as possible. Get two 3-axis mills running, go weld on the chassis some, come back and reset the machines, go weld more chassis... rinse and repeat 7pm-2am every day for way the $*#()@ too long...

[flavorPacket]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by JamesCH13:
Bearing housing walls were machine down to about 3/16 (ish) and because we expected some warping they will be machined out to 0.125" for a slip-fit to the bearings. </div></BLOCKQUOTE>

You can go down to .060" no problem. Just EDM some profile in the bearing cup wall to allow you to grab the weldment post-weld and mount it on a grinder.

And why are you doing a slip fit? Very few wheel bearings use that kind of fit.

[rjwoods77]

James,

Just to verify I was asking if the heat treat affected the bearing post diameters not the welding of them. What was your pre-welding and post heat treat dimension on the posts. By the way the way you are doing your uprights(fully enclosed welded sheet metal) is the hot ticket for light weight highest rigidity uprights out there. It takes much more work to get them done vs a cnc but it yields a superior upright as compared to a billet aluminum one.

[kapps]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by JamesCH13:
This is very true, but with just one old machine at our disposal we can only make so many parts in the time available to us. We have it running as much as we can. We use it to make things like stainless steel brake rotors, jigs, etc. The other problem is that it's in the basement and there is basically no ventilation, so we are not allowed to use coolant or oil on the CNC, making a 2 hour part an 8 hour part. But we do survive. </div></BLOCKQUOTE>

We're in a similar boat. We have an old 3-axis that can hold a 250kb code max (comes out to just over 10k lines usually). We can use coolant but mainly run without it due to the cleanup afterwards. It only has a 5hp motor and for times sake, I try to use as much of that as possible. Why do you think that not using coolant slows the run time down that far? For aluminum, you want to get the chips out of there. Running dry actually dictates a more aggressive cut so as much heat as possible goes into the chip. This year, I rigged up a little air blaster with a needle valve to control flow. It works great to keep the workpiece clear and temps down. Last year, our wheel hubs took over 10 hours a piece. This year, with a more refined program and actual thought of feeds and speeds, I got it down under 3 hours. Most of that was in the drilling operations where I only have one jacobs chuck and have to manually change the bits and re-zero a few times due to the length difference between drill bit sizes and reamers. For steel, I stick with coolant but the slower moving cutter doesn't fling it all over the shop. Luckily, I don't do much steel besides some bearing retainers and cutting the splined centers out of hardened gears making them idlers for Baja...

Oh yeah, those uprights are pretty sweet.

[flavorPacket]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by rjwoods77:
It takes much more work to get them done vs a cnc but it yields a superior upright as compared to a billet aluminum one. </div></BLOCKQUOTE>

That's quite a statement. Care to share any reasoning behind that?

The fact that it takes much more work cannot be ignored. If your car is rolling 2 weeks later because you use weldments, then you can't say they're superior...

Steel and Al are so close in stiffness/wt that, given the constraints you have on bearing sections and fit requirements, I have found aluminum to be more suitable for a fsae application in terms of mass (not cost).

[Steve Yao]

Nice work. Looks like you've learned a lot along the way.
We did very similar uprights from 2005-2007 although we included an internal rib in the lower section. We did not have to worry much about HAZ since we had them heat treated. Left the bores straight for welding and machined the bores post-heat treat...so 4130 rod and blast away with the TIG. Also you can cut down your total length of weld by using folded two-piece uppers and lowers instead of 4-piece, but this can lead to extra time grinding and fitting.

Went to alum last year to cut down the number of processes required... although considering the number of setups used in the mill center and the trial & error due to the decrepit machine being used, it's questionable if we came out ahead.

Are those caliper brackets for a floating caliper?

[JamesCH13]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content"> Are those caliper brackets for a floating caliper? </div></BLOCKQUOTE>

No, we are using a floating rotor.

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content"> I have found aluminum to be more suitable for a fsae application in terms of mass (not cost). </div></BLOCKQUOTE>

But their stiffness to weight is, as you said, similar. And steel doesn't fatigue.

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content"> Why do you think that not using coolant slows the run time down that far? </div></BLOCKQUOTE>

We machine a lot of steel, rather than aluminum, because steel is awesome. It has a much better fatigue life than aluminum. Like I said before, I can weld really fast, making welds not so much extra work as one might think.

Also, we got our hubs CNC'ed on a super-mill at our big sponsor: ConEd. They bought a 12 foot length of 8"diameter 2024! http://fsae.com/groupee_common/emoticons/icon_biggrin.gif

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content"> Just to verify I was asking if the heat treat affected the bearing post diameters not the welding of them. </div></BLOCKQUOTE>

Bennett, our heat-treating sponsor, said we shouldn't have to worry about any warping in the steel pieces we sent them. Still waiting to get the back. We are, however, worried that tempering our 2024 hubs will warp them, but again, still waiting to get them back.

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content"> You can go down to .060" no problem. Just EDM some profile in the bearing cup wall to allow you to grab the weldment post-weld and mount it on a grinder.

And why are you doing a slip fit? Very few wheel bearings use that kind of fit. </div></BLOCKQUOTE>

We are using tapered roller bearings, and I apologize, I meant to say the specified fit from Timken. We also did math and stuff showing that the wall thickness in the bearing housing has a reasonable factor of safety.

It must be nice to be able to "just edm" parts/fixtures. Our school is in the middle of downtown Manhattan, the size of our school and our location really constricts what we can make locally. Our school only has 1 mill, 1 cnc mill, and 2 lathes, only 1 of which has a DRO. We also wind up buying much of our own tooling because the shop supervisor is just waiting to retire (if you catch my drift). School policy also limits the time we have access to the shop. I am the welding lab supervisor, so we can weld any time we need to. But enough of that ranting, we still manage to get our stuff done, we just can't always do it with what most would consider the ideal method because of our unique circumstance.

Thanks to all for the compliments.

[flavorPacket]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by JamesCH13:

It must be nice to be able to "just edm" parts/fixtures. Our school is in the middle of downtown Manhattan, the size of our school and our location really constricts what we can make locally. </div></BLOCKQUOTE>

Oh, I understand. I grew up in midtown. I think you have made the right decisions for your situation. But when you are ready to make the next step and make an upright of competitive weight (1.4-1.6 lb), that's what you should consider.

In the meantime, you have a car to build, so don't let our intellectual masturbation get in the way!

[JamesCH13]

Well, is that weight of 1.4-1.6lbs with or without fasteners? We estimated the bolts we would need would weigh 0.2 lbs, but these designs have the bolts integrated. There is also still machining left to be done on them which will also reduce their weight. I will update once we get them back from Bennett heat treating.

[flavorPacket]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by JamesCH13:
Well, is that weight of 1.4-1.6lbs with or without fasteners. We estimated the bolts we would need would weigh 0.2 lbs, and there is still machining left to be done on them, which will also reduce their weight. I will update once we get them back from Bennett heat treating. </div></BLOCKQUOTE>

with spacers, bolts, and studs

[JamesCH13]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Posted March 15, 2009 04:11 PM


with spacers, bolts, and studs </div></BLOCKQUOTE>

What were the studs for?

[flavorPacket]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by JamesCH13:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Posted March 15, 2009 04:11 PM


with spacers, bolts, and studs </div></BLOCKQUOTE>

What were the studs for? </div></BLOCKQUOTE>

We mount our calipers radially with locating studs. Next year we will be doing a single-shear lower ball joint like you, so that will be another one (but with different geometry).

[Adambomb]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content"> But their stiffness to weight is, as you said, similar. And steel doesn't fatigue. </div></BLOCKQUOTE>

Is fatigue a problem? I did a fatigue analysis on our hubs one year, and with 7075 Al they had a fatigue life of something like the equivalent of 50,000 miles...at which point the entire rest of the car would have completely fallen apart. Since then I've sort have come to the conclusion that if it goes on the suspension and it's stiff enough, fatigue isn't an issue.

We used to run welded uprights, but got tired of spending a solid month on them. We've found it's much easier to beg and plead local machine shops to machine them for free http://fsae.com/groupee_common/emoticons/icon_biggrin.gif

Ironically, our steel uprights had a fatigue life of like 20-30 hours, but they cracked on a really pointy "break here" spot located right at the base of the dead spindle. They also weren't stiff enough...

[JamesCH13]

Well, as with any engineering decisions it's always possible to argue it any way you'd like. There are very few cases where steel, aluminum, or titanium has a clear advantage over the other two when fabrication, availability and cost aren't a factor.

In any event I find it very odd that your uprights weren't stiff enough. How did you figure that out or quantify it?

[RacingManiac]

Nice setup, the design and construction method is really similar to ours. We were(and to my knowledge for the current team, still is) very limited to CNC resources because our school has no CNC facility available to students, and school shop's pro CNC service is basically occupied with academic projects(machining a giant chamber out of a 700lb Al billet, sure...that'll be 3 weeks, gotta love that...), while outside machining sponsor's timing is based pretty much solely on their initiative and so we try to minimize CNC as much as possible. In fact in 2005 when we last CNCd both our uprights and hubs, they were 3 weeks late with the uprights. So these days we outsource the Hubs and make our own welded uprights inhouse. Manufacturing was pretty much the main reason we went with welded steel, it was important that we get as much control over our timing as we can and running car by mid-March is always the goal to make sure we get a whole lot of running done before comp. Welding 4 uprights was basically a weekend's work and spend another week for heat-treating at our sponsor and a day post machining the bearing bores. Can the CNC Al be lighter? Most likely. can they be as stiff? Possibly if we do a good job on designing them. Can they be done on-time? I doubt that. We usually have the maching design out to our sponsor in Sept, and in 2005 we got them back in parts by mid-late march. For comparison in 2006 and 2007 the uprights were done over Xmas and the car were rolling late Feb. Ours weigh in at ~1.8-1.9lb each...

http://www.supercars.net/pitlane/pics/70153/3315346d.jpg

http://www.fsae.utoronto.ca/20...uction/Rolling05.JPG (http://www.fsae.utoronto.ca/2007/pictures/2007%20Construction/Rolling05.JPG)

[Adambomb]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content"> In any event I find it very odd that your uprights weren't stiff enough. How did you figure that out or quantify it? </div></BLOCKQUOTE>

Well, we have an old design board that gave a COSMOS deflection of 0.07 deg/g, but I don't believe it. Also, design judge Steve Fox said they looked flimsy. It doesn't appear we have any good pictures, so I'll just describe: They were maybe 1.5 in. thick, ran a dead spindle that was at most 1.2 in. OD, made out of 0.065" sheet, and had some sorry excuse for double shear mounting that involved strips of sheet metal that were 1/4 in. wide where it really mattered. They also had bends and a bunch of goofy angles on everything, and were made out of like 8 pieces of sheet metal. After all this they still weighed something like 1.8 lbs, although with the dead spindle the hubs were a little lighter, like 0.7 lbs. All the ones posted here look 4 times as stiff and half as complex, and pretty much weigh the same.

Also, with the tiny spindle the wheel bearings needed tightened after every hour of driving, which is a pretty bad sign.

As for the "best" way, I'd agree that there really isn't a clear-cut winner between welded steel and machined aluminum, other than what you have the facilities or contacts to get done better. Stiffness per weight is practically identical, and 7075 is only 15% stronger per weight than 4130...although we are still stiffness constrained. The economy has hurt our sponsors, so if the budget looks too bad next year and our friendly neighborhood machinists can't hook us up I can see us re-designing them for good ol' steel.

Ooh, and if we have a numbers competition going here, this year's 7050 Al uprights are 1.25 lbs, should deflect an honest 0.1 deg/g, run true double shear all around, and run 2.6 in. bearings spaced 2 in. apart. Our front unsprung mass is 21 lbs with 20.5x6-13 tires and 9 in. steel rotors. They involved 8 hours of computation time in Matlab...outside of that I'm not talking!

[t21jj]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Adambomb:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content"> In any event I find it very odd that your uprights weren't stiff enough. How did you figure that out or quantify it? </div></BLOCKQUOTE>

Well, we have an old design board that gave a COSMOS deflection of 0.07 deg/g, but I don't believe it. Also, design judge Steve Fox said they looked flimsy. It doesn't appear we have any good pictures, so I'll just describe: They were maybe 1.5 in. thick, ran a dead spindle that was at most 1.2 in. OD, made out of 0.065" sheet, and had some sorry excuse for double shear mounting that involved strips of sheet metal that were 1/4 in. wide where it really mattered. They also had bends and a bunch of goofy angles on everything, and were made out of like 8 pieces of sheet metal. After all this they still weighed something like 1.8 lbs, although with the dead spindle the hubs were a little lighter, like 0.7 lbs. All the ones posted here look 4 times as stiff and half as complex, and pretty much weigh the same.

Also, with the tiny spindle the wheel bearings needed tightened after every hour of driving, which is a pretty bad sign.

As for the "best" way, I'd agree that there really isn't a clear-cut winner between welded steel and machined aluminum, other than what you have the facilities or contacts to get done better. Stiffness per weight is practically identical, and 7075 is only 15% stronger per weight than 4130...although we are still stiffness constrained. The economy has hurt our sponsors, so if the budget looks too bad next year and our friendly neighborhood machinists can't hook us up I can see us re-designing them for good ol' steel.

Ooh, and if we have a numbers competition going here, this year's 7050 Al uprights are 1.25 lbs, should deflect an honest 0.1 deg/g, run true double shear all around, and run 2.6 in. bearings spaced 2 in. apart. Our front unsprung mass is 21 lbs with 20.5x6-13 tires and 9 in. steel rotors. They involved 8 hours of computation time in Matlab...outside of that I'm not talking! </div></BLOCKQUOTE>

Here are the offending parts
http://img12.imageshack.us/img12/3286/frontrightassemblyold.jpg (http://img12.imageshack.us/my.php?image=frontrightassemblyold.jpg)

[L B0MB]

and a pic of the new design?.... http://fsae.com/groupee_common/emoticons/icon_smile.gif

[t21jj]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by L Bomb:
and a pic of the new design?.... http://fsae.com/groupee_common/emoticons/icon_smile.gif </div></BLOCKQUOTE>

Sorry, no can do.

[Adambomb]

You can see them in Detroit http://fsae.com/groupee_common/emoticons/icon_smile.gif

[JamesCH13]

That looks like messy business in fabrication.

An update: hubs are back from the heat-treaters. We asked if we should have holes in the enclosed sections... heat treaters said no... we were nervous about that, but they are the experts, in theory... The front uprights were fine. One of the rear ones, however, looks like a balloon. All of the panels are bowed out and the center bearing housing warped 0.20". We machined balls to the walls yesterday and made a new bearing housing in 5 hours and I welded together the new rear upright in about an hour. Luckily we had extra sets of panels and the "upright ends" (those threaded studs). DRILLED HOLES THIS TIME. Back at the heat-treaters.

[RacingManiac]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by JamesCH13:
That looks like messy business in fabrication.

An update: hubs are back from the heat-treaters. We asked if we should have holes in the enclosed sections... heat treaters said no... we were nervous about that, but they are the experts, in theory... The front uprights were fine. One of the rear ones, however, looks like a balloon. All of the panels are bowed out and the center bearing housing warped 0.20". We machined balls to the walls yesterday and made a new bearing housing in 5 hours and I welded together the new rear upright in about an hour. Luckily we had extra sets of panels and the "upright ends" (those threaded studs). DRILLED HOLES THIS TIME. Back at the heat-treaters. </div></BLOCKQUOTE>

Lessons to live by with welded upright.....if you drop by Toronto's pit I am sure someone can show you the exact same thing......We had one balloned on us back in 2006, we had to do the same thing to make a new upright, and from then on we've been putting small holes in the tube-gusset for the bolt-on camber block. We ended up cutting that upright in half and use it as prop to show in design presentation. Makes for a good story, and show off the design....