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Bullet Frame Repair/Steering Upgrade


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#1
Twister

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 Well after Havoc's whoops this year there was a lot of repairs. This was one. The shock popped and all hell broke loose. Blaine went for the finish with no front shocks just the bump stop bouncing off the axle. It was a good show. Since Blaine works out of town it was easier for me to take on the project.

 

 

 One of my all time favorite buggies.

 

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ah that'll buff out no problem

 

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It  tweaked it pretty good

 

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and the welded on rad hose wasn't going to make it any easier. The frame needed to be cut way back past the motor mount. Further would be better but that steel hose would cause problems.

 

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#2
Twister

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The absolute best and proper way to do this type of repair would be to strip the chassis. However we were trying to keep the repair minutes low so off came the shocks and the winch, the rest was left. The bump stop was stuck and I couldn't remove it so it stayed. When a rig is left together the difficulty level actually raises. While it seems like extra work removing everthing, it's a lot of work trying not to cut into parts or not get welding spatter everywhere. Even some extremely hard spots to reach with welding tips. Choose your greater evil I guess.

 

110.JPG   you can see the twist at the front support pillar and follow it back to the motor mount

 

 

The frame tube was damaged into the 90 degree bend on at the front. This meant to properly insert a new rail and install a proper slug we would have to cut the rail about 6" from the end of bend. At the begining  and end of bend towards the bend is where the tube starts to deform. So it makes it hard to insert a proper sized slug. Just after towards the straight part of the rail it regains shape.  What this means to us is that I had to cut the rial in the center of the nose. That meant removing the rail from several exisiting truss tubes and the nose piece.

 

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Each tube was slightly tweaked and all had to be re formed. This is why most racing buggies you see are plain straight tubes . Because A" anyone can build them  and B  they're super easy to repair. Personally having a sickass looking rig that's a bit of a pain to fix, that no one else has, is really important. Other people don't care and just want to drive.  

 

   Ya ever see the movie Troy    Little boy "I wouldn't want to fight him"      Achilles " That's why no on will know your name"   same goes for frame work.   "I don't want to do all those bends and copes and extra work"  -------



#3
Twister

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Frame rail gently cut out 

 

 

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If you take a close look I was able to pretty much remove the welds on each intersection tube and leave the origional cope. Meaning the lengths were all origional and realignment of the frame would be close and almost origional.

 

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small things to note in the picture are things like the stand under the motor to support it making sure nothing shifted while we cut the rail supporting it off.

or not in the picture are the stands holding the frame as well. This important because if something moves it could cause problems down the road that you

would never think of.



#4
Cody Ford

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As I try to broaden my knowledge on chassis building/design couple questions, what size tubing is the frame, and when you cut it apart, with everything supported, was there any spring back in the frame rail on the very last cut?  If there was, is this something you take into account when re-building the frame, or would you just re-measure everything when you re-make the tube?


90' C350 AKA 4 door 1 ton Bronco
96' Ranger: kings, EMF parts, 800hp SBF

#5
Twister

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Ha good question.

 

This frame is 2" .120 wall pretty much standard now for anything moving fast. When this chassis was built I was mocked for using such large tubing. 10 years later this rig is still here and there's are all garbage. :yahoo:

When you support the frame you don't want to support it anywhere that puts pressure on a rail connected to what you're cutting off. Move the support to areas on the other side of crossmembers or nodes. As far as supporting components  0 pressure when you add the brace. I use t-handle stands with screw jacks to set it perfectly. This will prevent any spring or tension release from hanging weight.

 

I always expect some spring however there's minimal spring when using DOM or ERW. Chromolly will always have a fair amount. That's why chromolly requires stress relieving in an oven after a chassis is built. Which I don't think anyone does. This is your field Cody.

 

Do I take it into account. If the rail or nose etc move then I use hyraulic rams to press the frame back into shape. It's not easy because you have to find the yeilding point of the part. To move a fabricated section such as the nose, on occasion  up to 6 inches of movement has been required to move a tube .1 inches . Go to much and everything kinks and becomes garbage.

 

Yes there was about 3/16 of an inch movement. The nose went up the fame went out. Every tube on the nose needed a bit of movement but I was able tomove them so that the new rail fit straight in.There's no pictures of that but it did happen.



#6
Cody Ford

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Good information, thanks. Tube size, I've always thought 1.75 and smaller for any major component is to small, not enough cross section. 

 

For the tubes moving when cutting, I would think with the way everything was bent you would end up with some residual stresses in the chassis that would be released when you cut into.  There shouldn't be much put into the chassis from the initial build unless you are clamping/bending/welding structure in place.

 

On the chrome moly, a PWHT for what we build should be done.  You can go without if you do your homework (proper welding consumables, heat input, material selection, etc), but the majority of guys building chassis's do not understand this.


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96' Ranger: kings, EMF parts, 800hp SBF

#7
Twister

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For the tubes moving when cutting, I would think with the way everything was bent you would end up with some residual stresses in the chassis that would be released when you cut into.  There shouldn't be much put into the chassis from the initial build unless you are clamping/bending/welding structure in place.

 

 

When I build I never pull anything together. It fits or it doesn't go on. The only stress would be from the impact.



#8
Twister

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114.JPG

 

115.JPG   There's a missing tube here it runs from the hood to the bottom of the front support. It was there the last time I worked on the rig. Years later it's two cut off chunks.

 

To fit a winch. The nose was designed for an 8274. I'm just clarifying the cuts

 

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The pictures show the remaining tube with copoes and if I remember right by hte time I took these the frame and truss supports had been mostly re shaped.

 

 

Okay I'm old school call me cheesy but every time I work on a battle scared rig this TV opening from the 6-million dollar man pops in my head. And this thing missing the one head light and the tarps. It just makes me laugh.

 

 

Actually I laugh a lot and know one knows why but it's honestly because  this flashes through my head over and over. Better bigger stronger faster.  Ahh the 70's so glad I grew up before everything became ...



#9
Twister

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cleaning the ends and the id of the tube help when trying to slide a tight fitting slug into a frame rail. Also sometime I use a round tube if the tube is damaged. It's a die I made that you pound into the tube and it re shapes it.

 

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The old frame looked pretty good inside for the hell it's been through.

 

 

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The new front corner

 

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#10
Twister

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Prepping the frame with rossette holes. I try to keep them in line and not too big but not to small. About 1/2 " in diameter.

 

 

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And try to make sure all paint/corrosion and crap is about 1 1/2 or so inches away from any weld. The fumes from contaminents any closer effect the shielding gas causing porosity . Something to think about. Cutting fluid and even debris from a buffing pad on the inside of the tube can cause the same.

 

 

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#11
Twister

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Easy bend making sure it's exactly 90 degrees. Any more or less would make it a pain in the a#s to slide the slugs into place.

 

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Rossette weld are only a part of it. I grind a slot along one slide of both the existing  tube and the repair rail. It adds surface area to the weld which addes strength. Wire is roughly in the 70 000 pound per inch strength range. the material I believe is 45-50 ish. The more linear footage the stronger it will be.

 

 

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#12
Twister

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Normally I use solid slugs but as long as it's a thicker wall tube it'll work. People sleeve .120 wall in and that's okay however the thin wall "could be" more susceptible to cracking or failing. I mean in reality it probably won't because it's now .240 thick with a butt weld and penetration to the slug. You have 12.56 inches of weld surface multiply that by .240 to get a cross section and you have a tensile of 168 000 pounds.

 

 

 

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but if you'r a geek you have to take into account the heat effected zone on either side and any undercut etc..... so I used 1.5inch .250 wall and turned it down. Brute force will beat brains in an impact any day.  On the frame side the tube tapered on the inside about three inches in .01. I think because of the weld zone so I machined that end of the tube .01 allowing me to slide the tube all the way in . Then place new rail and easily slide the tube into the new piece.

 

 

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Speaking of surface area we now have the rosette welds (which we'll drill and indent the tube) and the slot (which also helped allow us to slide the tube back out) and the circumference of the of the tube. This shouldn't go anywhere.



#13
Twister

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After I test fit both slugs in the new frame rail and the existing frame I was ready to try and put this thing together. The reason for test fitting ? well when you get lazy and jam a size on size tube inside a tube (even a slightly undersized tube) and it jams up on you during assembly it can lead to a bad day. If you're like me you get excited then agitated and the piece becomes permanently lodged in the tube resulting in hours of extraction. Or Jimmy rigging to correct you're massive error and then not being able to sleep at night hoping it never comes apart. This has happened to me many many many times.

 

 

 

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They were 8" slugs leaving 4" per side. Back to the test fit, if it jams on you it can lead to the slug only going in a little. When you're teching at certain events if they find out you may not be able to race. This would suck if you had driven 21 hours.

 

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The first part is easy you slide one end in the frame and if you have to tack the rosette hole to hold it in place. Then slide the new rail on. The tricky part is the second joint. Because it's a 90 the slug needs to slide into the rail, then the rail lied up and the slug slid out evenly into the opposing rail.

 

 

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Things that pose a problem   1) if your bend is greater or less than 90

                                               2) if either existing rail has a tweak or bend to it and does not line up

                                               3) if you didn't size the tube and it becomes stuck  (as I just explained)

 

 

Since I spent time sizing and unbending the rails prior to this step it all went smooth. Kinda like on power block. Reality it took me a day to make it that way.



#14
Twister

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The fitting stage. This is the part that you either win or lose. Is everything lined up and in place? or is there a butt load more work involved?

 

 

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looks good however the main rail that runs under the cab was tweaked a tiny bit and I had to use a strap to pull the nose in 1/4 of an inch. Not too much tension left.

 

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once they fit I worked my way through and started stitching

 

 

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The gaps were tighter than most peoples initial assembly. I was happy. Go time!

 

 

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This guy on the corner gave me some grief but that's because it was originally coped into another tube which is no longer around thanks to the winch. The nose piece was bang on though.

 

 

 

 



#15
Cody Ford

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but if you'r a geek you have to take into account the heat effected zone on either side and any undercut etc

 

On this part, as an FYI, the strength of the HAZ will be at least of what the weld consumable is rated for (when certifying welds consumable, whatever, this is included in the testing), or what the base material is rated, whichever is lesser.  Whenver testing welds (tensile, impact, etc), all zones of the welds, the weld metal, haz, and base material, is all tested to meet at least the lowest strength requirements of the welded joint.

 

Situations like this have always made me question as to how strong a tube splice, welded without a sleeve and using a true full penetration weld, is when compared to a non spliced tube.  Now if there is going to be a failure, it is likely going to occur at the joint due to stress risers and the fact that the weld is a stiffer section of the tube, but would it have failed anyway without the splice (whether its impact or bending load)?  Because I compare this situation to that of pressure piping, or in the structural steel world.  Sleeves like this are rarely/never used in the pressure piping nor in the structural would, only times you will see it when you backing for a full penetration joint for whatever reason.

 

Either way this is great info, Clay you need to post more of this type of thing up on here.


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96' Ranger: kings, EMF parts, 800hp SBF

#16
Twister

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Can do Cody. One thing I missed was pointing out the gap between the two spliced rail ends. It's almost .375 (3/8) of an inch. I weld with a pipe nozzle which allows me to concentrate my weld into a smaller area. This allows me to weld the one tube to the slug then the other. Followed by a cap dine with a normal nozzle.

 

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I Pre heat because the slug is thicker. Being thicker and welding into a blunt face the weld will cold lap on the slug if not pre heated. Two problems the tube is thinner and we're welding to the end. This means it will heat and melt instantly while the slug stays cold not allowing penetration creating the dreaded cold lap. Now I'm not gonna lie I do get cold lap here and there. Some times you just can't get the nozzle pointed right or you come into a corner. It happens.  However I make sure there's enough backing it in bracing or gusseting that it won't matter. Hence the gusset rules on cages.

 

 

 

 

Another point is that you want to try and make sure the slug extends at least an inch or two past any rosette hole or slot weld. The reason is tube flex around the haz  (heat affected zone)  The tube will tend to flex or move just past the slug. If at all possible keep the flex zone away from the heat effected zone. It prevents stress cracking. The further the better. Again not always possible. If they meet and there's no way around it don't lose your shit. Stay calm and fabricate on. You'll probably never see a crack. If you do fix it when it happens.

 

 

 

For once a job that went as planned I was able to weld it all out.

 

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speaking of hard to get spots. These tubes were incredibly hard to weld on the back side. The headers were right in the way. I had to get creative and use mirrors as well as bend the neck of my stinger to get the nozzle into a proper position.

 



#17
Twister

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A shot of the slot and rosette welds. Remember to do this when hot or these welds will be useless as they will just cold lap on the slug. Remember for added holding power to drill an impression (divot) into the slug through the rosette hole. Even if you cold lap it the weld will sit in the impression.

 

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Unless you're extremely horrible at welding (if this is the case you shouldn't be welding your cage)  it will bound with the external tube and act like a rivet. Also by drilling into the slug you create a heat riser and you thin the material out which will allow the wire to penetrate faster lessening the chances of cold lap.

 

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It's important when you weld the slot or rosette  to start from the center or middle and work to the out side edges. This ensures the bond to the slug. Working from the outside in only creates lap.

 

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On to the motor mount.Do I want to make another one or do I use my  20 years of scrap torching help me out?

 

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#18
Twister

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I'm going with torch shaving

 

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The motor mount hole is oblonged but it was ground that way.  After years of dealing with this I've learned to let it be and not fix it. In an engine compartment this tight you don't want to change a single thing. It will only lead to other problems. And the hole will be fine it's sandwiched between two washers sitting on a bushing pressed against another plate. It's not going anywhere.

 

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Here's where it gets tricky. Because the rail was bent when I got it, I have no idea how the mount sat.  I have no pictures prior of it and its been almost 10 years since I built it so I can't remember. Bolted soild to the mount on the block and then with a bushing in between it sat exactly like the picture. Your mind says put it on straight but logic says that would put stress on the bolt. My choice was to mount as it sat.

 

 

        Who cares right? well most fabricators don't but I do and the cast surrounding the mount bosses on the block do as well. Ever hear someone say they hit so hard they cracked the block? Well they didn't, they just mounted the mounts wrong. It'll transfer there or to the frame rail. You might not see the effects directly what you might see is constant internal failures in the block. Oiling issues or mains constantly wearing out. It's amazing what a bad mount and torque from a bolt can do. And yes I've experienced all of these things first hand.

 

 



#19
Twister

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again the difficulty level was high getting the stinger in and around with the motor still installed.

 

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The bump stop was fun. The tube was warped from the frame twisting so there was no way I was getting it out. I decided to zip disc it. Holding my breath the entire time. Obviously I let the pressure out first. But I was just waiting to cut through the body by accident as I sliced the canister.

 

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and I did it with no scratches. Sometimes you get lucky.

 

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 Time was a problem and I didn't have enough to order a new tube so I found a piece of tube in the shop and made a new tube.

 

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because I dislike this style of canister and how they always tighten up after welding them to the frame I machined a little clearance in. I gave it .015 extra diameter.

 

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#20
Twister

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Then to match the other three the tube was spun to the same o.d.

 

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Again trying to retain the original look of the buggy and matchining the driver side the gusset and stiffener were shaved off the old frame  and re used

 

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and re mounting the canister to the same spot. If I was smart I would have coped this prior to welding the frame in place. I got excited when everything fit and welded it all in like a dumb ass.   :wallbash: So I had to cope in place using an incredibly slow process that Blaine explained to me. 

 

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taking the stiffener/gusset into place it helped line up the mounting position. Not the easiest task in a corner on the side of a tube that's been replaced. 

 

 

 

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Once it was tacked in place and the suspension was cycled making sure the bump connected in the right spot on the landing pad it was weld time.

 

 

 

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