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Author Topic: XJ Frame Stiffeners (or how to waste time on side projects)  (Read 12834 times)

Offline frijolee

XJ Frame Stiffeners (or how to waste time on side projects)
« on: November 07, 2016, 03:09:20 PM »
I might as well have titled this thread:  Where the F has Joel been?

Well after I snapped my Jeep Cherokee's track bar mount hauling the FJ40 into my garage, I ended up doing a pretty healthy round of mods to the XJ that are *almost* done (taking my girls 4 wheeling this weekend so it better be).  Anyways, I've had a running build thread on my XJ (Jeep Cherokee) over at Naxja for some time now.
http://naxja.org/forum/showthread.php?t=1081640

NoRotors is still the "home forum" and I figured this might give some folks an little entertainment and I figured I'd post up the latest efforts.  It's still a stock Jeep 4.0 so it wasn't quite worthy of a build thread so I'm shoving it here in fabrication just because there was a lot of that.  Commentary appreciated as always.

-Joel


« Last Edit: November 07, 2016, 03:37:49 PM by frijolee »
LS2 stroker FC, Mandeville big brakes, widebody, etc
Build thread:  http://www.norotors.com/index.php?topic=1274.0
www.roninspeedworks.com

LargeOrangeFont says: "Joel is right, and I love Joel. But his car sounds like the wrath of God."   ;)

Offline frijolee

Re: XJ Frame Stiffeners (or how to waste time on side projects)
« Reply #1 on: November 07, 2016, 03:12:12 PM »
This was written for another forum so forgive me if some things come across out of context. 

Picking up from the track bar failure...

______________________________________

Remember all the dual shear track bar stuff we talked about earlier in this thread?   Yeah, apparently I should have moved out faster doing something about that.




Did the criss cross strap trick to get it home.




In skimming through prior posts, I've had recommendations for off-the-shelf dual shear track bar mounts from Clayton, Rubicon Express, and Rock Krawler.  Is there any reason not to just fortify the existing bracket and turn it into a double shear?  I have a plasma cutter, spare 1/4" plate steel, and welding capabilities.

Someone remind me, what are the rules about pivot geometry?  I think it was basically node to node, have track bar and drag link run parallel at ride height (and as equal length as possible to keep them parallel through travel). 

I'd like to use what of my BDS kit I can.  I will be adding a bend to my drag link as well since that got pointed out.  I do still have this 2" ballistic joint laying around.




But some of you guys didn't like it much and suggested it would wear quickly.  There were suggestions of a Johnny Joint (any particular size??) or just a 7/8" heim.  I kinda think I'd like to avoid a heim since this rig is pretty street friendly.  I'm really tempted to run the joint I have, since it's the fastest fit I can see.  Is the wear a problem of keeping it lubed or is this just fundamentally the wrong joint for the job? 

Pressure's on since I need to get this fixed quickly and the rest of my projects aren't running at the moment (rx7 at body shop and others are a long way off).  You can only steal the wife's car so often, before you start to violate the "happy wife = happy life" rule.  Any final advice or specific links would be greatly appreciated.

-Joel



LS2 stroker FC, Mandeville big brakes, widebody, etc
Build thread:  http://www.norotors.com/index.php?topic=1274.0
www.roninspeedworks.com

LargeOrangeFont says: "Joel is right, and I love Joel. But his car sounds like the wrath of God."   ;)

Offline frijolee

Re: XJ Frame Stiffeners (or how to waste time on side projects)
« Reply #2 on: November 07, 2016, 03:13:11 PM »
Track bar redo...

The BDS stud was fatigue cracked just about all the way through before it actually let go.




Former 2" joint (which was sloppy to boot) and new 2.5" johnny joint.




BDS uses solid bar.




Solid bar is hard to weld.




Pre heat, sharp tungsten, and a tiny weld deep in the root.  Better.




Now we're getting somewhere.




Seemed like I was fighting my setup the whole time.  May have been the gas bottle hitting the dregs, but man I ground out a lot as I went along.  Should be plenty of weld though...

LS2 stroker FC, Mandeville big brakes, widebody, etc
Build thread:  http://www.norotors.com/index.php?topic=1274.0
www.roninspeedworks.com

LargeOrangeFont says: "Joel is right, and I love Joel. But his car sounds like the wrath of God."   ;)

Offline frijolee

Re: XJ Frame Stiffeners (or how to waste time on side projects)
« Reply #3 on: November 07, 2016, 03:14:04 PM »
On to the bracket side:

Paper doll study after cutting off the bottom inch or so of the stock bracket.  This would have been nice because it aligned to the new side plates better than where I ended up.




Round 2, doll.




Major change was shifting it forward to be sure I'd clear the truss.




New tool.  Finally had an excuse to use my plasma cutter.  I'm a fan. 




Tacked, clearances looking good.




Now that's what welding some thick stuff is supposed to look like.




Weld through primer on the bits I can't paint later (price tag might as well say clutch your ankles but it works well).




Tying in a side plate:




 Vertical mid gusset helps carry the load from the aft plate up to the bolt pattern.




I ran out of Argon and had to switch to MIG to finish.




Painted and ready for install (assuming tonight)




Outside:

LS2 stroker FC, Mandeville big brakes, widebody, etc
Build thread:  http://www.norotors.com/index.php?topic=1274.0
www.roninspeedworks.com

LargeOrangeFont says: "Joel is right, and I love Joel. But his car sounds like the wrath of God."   ;)

Offline frijolee

Re: XJ Frame Stiffeners (or how to waste time on side projects)
« Reply #4 on: November 07, 2016, 03:15:34 PM »
What have folks done on the axle side track bar connection point?

One end is going to be a great deal more beefcake than the other and I'd like to avoid this:




Simplest approach seems to be just adding a double plates on the outer surface But adding thickness compounds another potential issue: I'd really like to shift the track bar closer to the axle if I can. My tie rod has always rubbed the bolt head as I approach full lock and bind anywhere in the steering system ain't happy.  Anyone know what's hiding back there if I try to cut it out and replace the box?
LS2 stroker FC, Mandeville big brakes, widebody, etc
Build thread:  http://www.norotors.com/index.php?topic=1274.0
www.roninspeedworks.com

LargeOrangeFont says: "Joel is right, and I love Joel. But his car sounds like the wrath of God."   ;)

Offline frijolee

Re: XJ Frame Stiffeners (or how to waste time on side projects)
« Reply #5 on: November 07, 2016, 03:16:22 PM »
Here's a couple notes finishing up the track bar stuff...

I did end up reinforcing the bottom trackbar/axle interface.  I figured can ditch the washer the bolt was using and not be much worse off in terms of tie rod interference.

Little plate of probably 0.095" (basically a doubler)




Weld-through primer on both inside faces.




Burned in and painted:




Johnny Joint assembly was a PITA.  This is a 2.5" CE-9110P by the way...



Looks simple enough.  Although, I'm not convinced the two big washers actually fit in the bore (it'd be close and I didn't check ahead of time).  After you weld on this, the bore isn't quite perfectly round and those washers definitely need a healthy shave on the perimeter. 

So after a washer finally fits all the way down against the step, then you ram one of the rubber bits down in the hole (greased, but it's still so tight it's not easy), drop in the ball, swear at the other side when you realize you can't get that in the hole straight enough for the interlocking bits to line up. 

Switch to the press.  Line the two rubber bits up perfectly and press it in with a big socket.



Seems to be working but it's spitting the grease back out the fitting hole.  Install fitting to see if you can force great everywhere rather than it just taking the path of least resistance.  Re-press and find that the two rubber bits are so tight to the bore that now the grease hydraulically locks the system and you can't press it.  Remove fitting, finish the driving the upper half home.

Pull it out of the press and realize: A) the upper rubber bit isn't perfectly flat so your alignment of the two halves must not be as good as you thought.  B) There's no way you're getting that gnarly heavy snap ring the groove without some serious side pressure to hold the washer down.

So then you pull everything apart, re-evaluate your setup and start again.

The right way to do this (or at least what worked for me): 




Use a smaller socket (just enough to pick up the washer ID), press-in the entire assembly all at once so the sides are sure to be lined up with each other.  The snap ring dangles over the top so you can snap that around the socket, which just fits.  Release pressure.  Add grease fitting.  Pour yourself a fireball on the rocks for a battle fought and won.
LS2 stroker FC, Mandeville big brakes, widebody, etc
Build thread:  http://www.norotors.com/index.php?topic=1274.0
www.roninspeedworks.com

LargeOrangeFont says: "Joel is right, and I love Joel. But his car sounds like the wrath of God."   ;)

Offline frijolee

Re: XJ Frame Stiffeners (or how to waste time on side projects)
« Reply #6 on: November 07, 2016, 03:17:21 PM »
ZJ rear disc brakes started but I ran into an issue with an axle shaft...  More on that in a second. 

1) Support car, remove wheels, remove outer brake drums. Can you tell which side had the bad shaft seal?






2) Open up the rear end to access C-clips, remove axles.  Note, Truetrac's have an access port and a spacer instead of a cross pin.



3) Disconnect e-brake lines, not using either of the factory lines. 

Note: E-brake cables seem to be one of the bigger points of uncertainty with this swap and various folks have done different things.  Following the advice of this thread: http://www.cherokeeforum.com/f2/zj-disk-brake-ebrake-cable-36835/, I settled on using the ZJ driver brake line and NAPA p/n 95064 for the passenger side.  Supposedly no need to do any crazy looping of cables and the best fit of available options (passenger is a little longer but that's not bad for a lift). 

4) Remove drum brake internals with the four nuts at the backing plate.  Remove the brake line last and be ready to catch drips.  I used several layers of syran wrap and zip ties.  Do it tight enough and it won't leak. 

Still to come:

5) Grind open ID bore of the ZJ backing plate.
6) Install all the new bits pretty much like how they came off the ZJ
7) Reroute brake lines (need the ZJ soft lines for this)
8) Install ZJ prop valve.


But the reason I stopped where I did...  was cleaning up a bit and noticed I have some wear on the bearing surface of one of my axles.




Actually looks worse in a macro picture than in person, but you can still feel it with a fingernail.  On a scale of "minor" to "you're F'ed, change that NOW" how would you rank this?  I will swap it out as soon as I can but I don't know that I can get a new shaft prior to my planned road trip Monday morning.  It wasn't making noise, and ironically, this was the shaft side that wasn't leaking.  Effectively, am I an idiot for even considering driving another 1000 miles on this--with a day of wheeling to boot--before changing it out?  Assuming I'll need a bearing too.

What manufacturer do you guys like for the late model (29 spline) 8.25" shafts?  Is it time to go chromoly and keep the stocks as trail spares?  97-01's are a bit more rare in the local junkyards, but I can check.
LS2 stroker FC, Mandeville big brakes, widebody, etc
Build thread:  http://www.norotors.com/index.php?topic=1274.0
www.roninspeedworks.com

LargeOrangeFont says: "Joel is right, and I love Joel. But his car sounds like the wrath of God."   ;)

Offline frijolee

Re: XJ Frame Stiffeners (or how to waste time on side projects)
« Reply #7 on: November 07, 2016, 03:18:09 PM »
The Santa Fe Springs Pick Your Part claims it has two late model XJs, a 97 and a 2000. Decide it's worth it to show up and grab shafts. Found both. One the rear axle is gone but the other is whole. Sweet.

Go to pull it the shafts and the cross pin retainer bolt strips. DAMMIT!!!!!  I'm F-ed.  No way to get those out now. If I were at home I'd weld a nut to it.

Debate seriously yanking the full axle but I have no idea if these shafts are any better than what I have.  Screw it, not worth it, looks like I'm ordering axles and gonna assemble this twice (assuming I can even get my list done to take it in the first place).

This sucks.  Hot. Hungry.  Tired. Dirty.  Long list still needs to be done today.

Well at least it's lunch time. I need a happy meal.  Carne Asada Fries.... Yeah that ought to help.
LS2 stroker FC, Mandeville big brakes, widebody, etc
Build thread:  http://www.norotors.com/index.php?topic=1274.0
www.roninspeedworks.com

LargeOrangeFont says: "Joel is right, and I love Joel. But his car sounds like the wrath of God."   ;)

Offline frijolee

Re: XJ Frame Stiffeners (or how to waste time on side projects)
« Reply #8 on: November 07, 2016, 03:19:00 PM »
Mmmmm, carne asada fries...  The ultimate Southern California happy meal.




Well, I didn't finish the Jeep in time for my camping trip... but you know what?  It was OK.  I still made huge headway at getting the Jeep sorted and Kings Canyon was still rad in the family hauler even if we did zero off roading.

It was still big and beautiful...




And the girls loved the outdoors, especially the creek stomping.




So now we're back and it's back to work.  Frame stiffeners are well underway and so is the rear suspension redo.  A few questions: 

1) Bastard pack setup...  I'm blending a set of BDS 4" springs that sagged with something random I pulled out of a junkyard MJ.  Planning to swap in the middle two MJ leaves for the similar length BDS leaves and see where that puts me.  1.5-2" lift would be ideal vs now. Any opinions on pros/cons of the big dog bottom leaf from the MJ vs. the two smaller leaves (bottom most) with the BDS?  Here's what I'm playing with:




2) Picked up a set of Daystar extended bumps (4.1").  How much engagement I should build into the bumpstop before the shocks bottom?  Shocks will be Bilstein 10" 5100s.

3) The nose of the Daystars is more rounded than stock (see http://www.daystarweb.com/productdetail.php?productID=369) so I'm debating adding a dedicated perch for bump engagement on the axle tube.  Something like an extra leaf pad that I could stack shims on. Good idea or no point (aka bare tube is fine)?

Thanks for the advice as always.
-Joel
LS2 stroker FC, Mandeville big brakes, widebody, etc
Build thread:  http://www.norotors.com/index.php?topic=1274.0
www.roninspeedworks.com

LargeOrangeFont says: "Joel is right, and I love Joel. But his car sounds like the wrath of God."   ;)

Offline frijolee

Re: XJ Frame Stiffeners (or how to waste time on side projects)
« Reply #9 on: November 07, 2016, 03:19:39 PM »
Found a possible answer on the bump stop engagement.

http://www.fourwheeler.com/how-to/0904or-bump-stop-tech/#photo-08



Unless anyone else has more specific feedback I'll likely set mine at 1" plus the full height of the cutout window (another 3/4" maybe? need to measure) before shock bottoming as my starting point. 

A few questions still outstanding above.
LS2 stroker FC, Mandeville big brakes, widebody, etc
Build thread:  http://www.norotors.com/index.php?topic=1274.0
www.roninspeedworks.com

LargeOrangeFont says: "Joel is right, and I love Joel. But his car sounds like the wrath of God."   ;)

Offline frijolee

Re: XJ Frame Stiffeners (or how to waste time on side projects)
« Reply #10 on: November 07, 2016, 03:20:26 PM »
Iím way behind on these updates but at least Iíve been making some good progress so hereís some more info.

Frame StiffenersÖ supposedly key to XJ longevity.  Since I decided it was worth upgrading my Jeep a bit more, I bought the full front/mid/rear kit from HD Offroad Engineering. 
http://hdoffroadengineering.myshopify.com/products/xj-frame-stiffener-set  Reviews on fit were good.  I likely the goldilocks ďjust rightĒ thickness at 0.135Ē and the time savings having someone else burn and bend these easily justified the cost.  Plus it's cool to support someone who's really focusing on the XJ.

Downside was that Iíd screw up the width of my fancy mid skid since that bolts in from the sides.
 



Iíll have to fix that to install stiffeners but still went for it.

The stiffeners ship bare (no box!) tack welded together in two bundles with labels stuck on random faces.   It kinda seemed chincy, it kinda cracked me up, but they still arrived without damage so I guess it works. 

Started prep by drilling out the 6x skid plate points per side.  I was planning to reuse the hole positions but wanted the stiffeners in tight to the rails and was worried what might happen if these gloried rivet nuts ever failed and spun.






I ended up with 9 jackstands supporting the vehicle.  2 on the gas tank skid, 2 big 12 ton jobs on the front bumper, 2 on each axle, and one for the transfer case. 



The BDS transmission subframe was left in place, dangling down.  I took this up and down a bunch of times doing trial fitments.  It dangles by the weld nuts as it would have to slide in above the frame rails if you took this all the way out.

Pro Tip:  Donít drop a lower control arm on your head, especially a long arm.  9 stitches (3 internal) and a tetanus shot laterÖ



Funniest moment in the ER.  My wife grabbed a book and is reading to us while we transition from the various waiting rooms.  Didnít think about it, but we happened to be re-reading on of the Harry Potter books.  Talk about dudes with FAMOUS FOREHEAD SCARS!  I was laughing for a while after I realized that, even while they were trying to sew on me.

Ok, back to the projectÖ

Grabbed some remnant stock from work and sliced up a bunch of little disks so would have some proper threads to engage into by tapping this after the fact.  Used magnets to hold it while I burned them in and felt clever with my forethought (more on this later).






After I ground these most of the way back flush, I moved over to prepping the actual stiffeners.
LS2 stroker FC, Mandeville big brakes, widebody, etc
Build thread:  http://www.norotors.com/index.php?topic=1274.0
www.roninspeedworks.com

LargeOrangeFont says: "Joel is right, and I love Joel. But his car sounds like the wrath of God."   ;)

Offline frijolee

Re: XJ Frame Stiffeners (or how to waste time on side projects)
« Reply #11 on: November 07, 2016, 03:21:33 PM »
Fit was quite good but could be improved ever so slightly.  Rear of the mid stiffener was notched with a 1/4" step on both sides to clear the leaf spring mount.




I also notched around the two frame rail gussets on either side.  Hereís my estimate.




One of the rear stiffeners was missing a couple rosette holes so I added those back in.  Grinding disc made a decent circle cutting guide.




Last comment would be that I took about ľĒ off the top curve to the left of my gusset notches.  Actually both top and bottom radii could be larger but I wasnít going to add material back in.  Not sure if these were late model changes (Iím a 1999), but Iíll try to get this to HD Offroad to see they want to make some subtle improvements.




Did a few rounds of bending in appropriate places to optimize fit since tack and hammer fitment only gets you so far.




All stiffeners and frame rails also received a healthy dose of weld through primer before I burned these in.




Here was the last trial fit and you can see what I meant about the radii.




Last thing to do was to add the holes for E-brake cable tray and my specific trans subframe.  Thatís not that interesting so I didnít stop to grab a picture.

All in, I was still a pretty happy camper as I got welding.  Rare mug shot, because I liked the mad scientist hair (this was at some point before I smacked my dome).




Notes on welding next...
LS2 stroker FC, Mandeville big brakes, widebody, etc
Build thread:  http://www.norotors.com/index.php?topic=1274.0
www.roninspeedworks.com

LargeOrangeFont says: "Joel is right, and I love Joel. But his car sounds like the wrath of God."   ;)

Offline frijolee

Re: XJ Frame Stiffeners (or how to waste time on side projects)
« Reply #12 on: November 07, 2016, 03:22:35 PM »
Thoughts on welding frame stiffeners.

1) Donít even both trying a tig welder (too many gaps and overhead work jammed against rails and/or the floorboards).  Probably obvious, but worth stating.

2) A 110 V mig is plenty for these, I blew through the frame rail twice as it was (frame rail is thinner so itís not hard to do).  Iím using a little Millermatic 135 on the bottle and it kicked ass and took names.

3) I also used a big wire wheel to get things close and then only removed paint with a flapper disk at each point I planned to weld.  Iím really doing all I can to keep this healthy long term and sandwiched metal can be a corrosion risk.  Then it all got wiped down with denatured alcohol prior to the weld through primer (U-POL #2).

4) I started from the middle using a combination of a floor jack and 2x4 from below and C-clamps from the sides.  On the first rail I started jumping every three holes, but having looked at how far the heat affected zone goes I donít think concentrated heat is much of a problem for the rosettes.




I experimented with a few different methods and sequences of burning.  I found that if you just weld in a spiral from the middle all the way out to the stiffener the rosette hole is large enough that you can blow through the rail.  To be fair, I was welding pretty hot.  It also can end up with a pretty big weld (more to grind later).





Doing this on jackstands sucks.  Sitting on the ground left my head banging against the rocker at eye level and it was hard to see without putting your spine in a pretzel to get low enough.  I got a little lost on one...





The best technique I worked out for the rosettes was this:

1) Start with a ~2 second pulse in the middle of the rosette hole.  Itís just welding on the rail at this point but itís building up and getting things hot (especially helpful when thereís any kind of gap between rail and stiffener.

2) Pause long enough for the glow to get back to kind of a dark cherry red.  Maybe

3) Do a finish pass tracing the classic MIG cursive letter ďEĒs around the perimeter of the hole tying stiffener to the build up you made a few seconds ago.   

After doing the side rosettes I added the stitch welding along the edge.  Some folks claim you donít want to weld the whole edge else as its good to have some frame rail maintaining parent material strength.  Made sense to me so I stitched the seam between every other rosette hole.  On the stitch welds I did do two passes from end to end to keep the heat moving around (every other stitch on each pass).




I basically did 100% of each vertical face on the mid stiffeners before moving to the bottom surface.  On the bottom fact my rail had a few dents that formed a little gap in places.  The horizontal leg is also pretty short.  As such, here I stitch welded first (and got my 2x4 smoking a few times in the process).




By the way, if you do blow through the frame rail while welding on the bottom surface itíll drop a decent size blob of molten metal so you do NOT want to be directly underneath this thing, itís just too easy to do that. 

If you do drop a blob of molten metal on your driveway, when you go to weld up the hole you just made, you may or may not notice that you just set the driveway on fire next to you.  Not that Iíd know anything about thatÖ  Just saying.




Very last area I did was the gaps for bending on the mid stiffeners.  Brian (HD engineering), nailed the placement on these.  I used a filler pass on rail only to shrink the gap a bit and then did a full pass swinging back and forth all the way to the edges welding uphill. Seemed to work out pretty well.



By the way, the rosette weld on the right in the pic above is a pretty good example of what I was shooting for.  I did grind all the rosetteís back to flush since I need a relatively flat surface to tie my big skid plate back into.  Iíd picked up a big dog 8Ē angle grinder at a garage sale a while back and used the heck out of that thing.  The masking tape at the top helped avoid getting shavings behind the stiffener.  Iím planning to use seam sealer after I get it painted.

Expect the ground to be pretty furry with shavings by the time youíre done grinding.




Front frame stiffeners tuck behind the front bumper side plates so Iíll need to move my jack stands before I tie those in.  Process should be the same.
LS2 stroker FC, Mandeville big brakes, widebody, etc
Build thread:  http://www.norotors.com/index.php?topic=1274.0
www.roninspeedworks.com

LargeOrangeFont says: "Joel is right, and I love Joel. But his car sounds like the wrath of God."   ;)

Offline frijolee

Re: XJ Frame Stiffeners (or how to waste time on side projects)
« Reply #13 on: November 07, 2016, 03:24:03 PM »
Remember those frame rail steel plugs?  Didnít work want to thread as planned!

Sometimes when youíre pushing hard trying to get something done you make decisions that come back to haunt you.  Sometimes shortcuts work out OK.  Sometimes you think you can get away with more than you can.  Iíve often told non-car people that wrenching on cars is about overcoming the unexpected difficulties that crop up.  Whether itís the rusted bolt you just broke, or the part that didnít quite fit like expected, you can never productively finish projects unless you can find a way to overcome those challenges.

I knew Iíd set myself up for some pain, drilling 12x holes through ~1/2 steel by hand.  Thatís not easy nor particularly fun no matter how you slice it.  For drilling steel I like using about 1/8Ē bit.  Bigger and itís too slow.  Smaller and itís too easy to break bits pushing with enough force to get it to cut (and not just smoke the bit).

First four pilot holes drilled OK.  I was using basic Harbor Freight Titanium Nitride Bits (their basic machinist set).  Hole 5 gave me a bit of a challenge, had to break out the drill doctor.  It was still kinda slow cutting so I reached for the small set of Dewalt split point bits I had and drilled all other 8 positions without too much difficulty.

Whew, hard part past Iím thinkingÖ  Now that I have pilot holes I should be in the clear.  Jumped up to an "H" sized bit (Ti Nitride again) as Iím only planning to tap for M8 bolts and they donít have to be huge.  Again first four holes drill fine.  5th holeÖ  Will not cut.  Drill doctor again, make sure the bit is perfect, plenty of cutting fluid, varying pressures, varying speeds.  Will not cut.

Iím not ready to give up so I head over to HF and buy their machinist cobalt set.  Those werenít out when I originally bought my other ones a decade ago.  Yes, you can get stuff thatís more bad ass, but Iím pretty careful and Iíve had decent success using their stuff in the past.  Cobalt set still runs $110 in drill bits, they're a little brittle but good in a pinch.

Take it back home and manage to drill all the holes.  #5 on driver side is still the sticky spot but at least I prove the drill doctor works on cobalt bits too.  Split point on that bit gets a bit shaved down in sharpening but I can live with that.  Any time Iím reaching for a cobalt bit this big Iím going to have a pilot hole already.

OK, time to tap this thing. 

Iím up again the bottom side of the rig, but I figure out I can use a square drive socket and wrench to apply torque with good force and still keep the tap stable and straight.  Definitely going to use this trick again...




Again first four holes go OK.  Takes some significant torque to cut but itís working.  I can feel it start to bind up so Iím reserving regularly to break my chips.  I have Tap Magic cutting fluid dripping off this thingÖ  Basically Iím doing everything right that I know of.

Hole 5:




Back out the tap and it's fubar'ed about as deep as I cut... Dammit.  Couldnít feel the difference between cutting threads and the plug ripping the teeth off my Craftsman tapÖ  What the F was this metal?  The stiffener itself cuts like butter by comparison.

So I take the bar stock I used into work and we break out the hardness testers.




Exterior of the bar measures 27 HRC.  Thatís not mild steel but it isnít too ridiculous.  Head machinest sends me home with a bad ass tap, supposedly rated to 45 HRC and some Castrol Moly Dee cutting fluid.  We also talk about opening up the pilot holes a bit to make things easier.

I get home and drill all the hole out to a ďJĒ without much difficulty.  I start using the bad ass tapÖ  chase the first four holes and get some decent crap cleaned out of there.




Hole #5, get it startedÖ  ITíS CUTTTING!  Iím being as smooth as I can beÖ  I just start to feel the chips loading, I hear the tiniest of cracking noises, so I go to reverseÖ and promptly break off the tap in the hole.




Well, Iím not fitting an EDM under my car to burn out a tap and/or cut threads.  Iím doubting this is tappable at this pointÖ and I owe my machinest a $30 tap.  Screw it Iím done.  Sometimes, you can overcome the difficulties, sometimes you have to know when to cut bait and run.  Iíll just have to add fresh holes in a different position.

I wish this story had a happier ending, but for the moment itís mostly a cautionary tale.   I was just pushing too hard to keep things moving that a shortcut in material choice burned me bad.  Live and learn.

I was frustrated enough that I couldn't stand tapping another hole and I moved on to other things... 




-Joel
LS2 stroker FC, Mandeville big brakes, widebody, etc
Build thread:  http://www.norotors.com/index.php?topic=1274.0
www.roninspeedworks.com

LargeOrangeFont says: "Joel is right, and I love Joel. But his car sounds like the wrath of God."   ;)

Offline frijolee

Re: XJ Frame Stiffeners (or how to waste time on side projects)
« Reply #14 on: November 07, 2016, 03:24:31 PM »
So now that Iíve added frame stiffeners, here comes the skeptical partÖ  Everyone swears by frame stiffeners but it always seemed to me like a really inefficient way of adding torsional rigidity to a unibody.  On the one hand I know that a cage tied into the roof pillars would be orders of magnitude better, but Iím trying to keep this family friendly.

My XJ already had welded rectangular tube at the rockers, but Iíve heard of folks whoíd hit down hard enough on these to collapse the body above.  As such I decided that if I was going to do frame stiffeners, the least I could do would be to tie in the rockers and end up with more of a ladder structure on either side of the body rather than discrete parallel stiff elements connected by only sheet metal.  This was the plan from first ordering frame stiffeners so I did it immediately following.

I started into this planning to use two 2x2s and two 2x1ís stingers on each side, with the 2x1ís allowing me to keep enough clearance to the prior hole pattern for the big aluminum mid skid.

Plasma cutting w/ guide.




Cleaned up and ready to bend ends inward.




Not shown: welding the angles, adding drain holes, and a quick shot of weld-through primer on the insides, but here they are burned in.  Slightly larger spacing up front than for the back three to clear my BDS transmission subframe bits.




Since I was abandoning my planned mid skid hole locations (see drilling/tapping fiasco posted above), I ended up making a few more of these stingers and running the equivalent of 2x2s everywhere.

My rocker is 3/16Ē wall which is a little more than my MIG is supposed to be used for.  I used a MAP gas torch to preheat the rail and was happy with the penetration and results. 

LS2 stroker FC, Mandeville big brakes, widebody, etc
Build thread:  http://www.norotors.com/index.php?topic=1274.0
www.roninspeedworks.com

LargeOrangeFont says: "Joel is right, and I love Joel. But his car sounds like the wrath of God."   ;)