ECORS XJ Build Discussion

Alright,
A few friends and I are planning to build an XJ to race in the 2011 season of ECORS racing, in A class.

Wanting to make this XJ as tough as nails, on a budget from hell, what this means is that anyone who has never been to PAP need not reply, anyone who wants to give me a laundry list of expensive items to buy, need not reply. I do not want to be rude, or a jackass, but I am sick of the "Why are you doing that, just order the $300 kit" answers I get.

Basic Plans.

Buy Cheap Craigslist XJ, do basic tune up
Gut interior from the driver seat back, leaving just the 2 seats.
HP Dana 30, probably do the 760 u joint upgrade.
Almost Alloy U joint Tabs
8.8 rear axle swap, either LSD or welded
5-6" lift, Bastard pack rear w/ shackle
Ford f150 lift coils up front (Stiff, not going to bottom out, will take the abuse)
Tranny Cooler, Debating a PS Cooler also.
V8 ZJ steering setup
hack + tap sye
Possibly build a basic skid plate for the underbody, nothing too complicated, but have to look into that still
15x8 Steelies
33x12.50 M/T's or 35x12.50 M/Ts depending (LSD 8.8 35s, welded 8.8 33's)
Homebrew Sliders and Bumpers w/ winch front, towpoints rear.
Toolbox to fit into the rear to carry straps, tools, whatever else.

Basically, what we need to know, whats the best way to brace the XJ unibody? Key Stress points? Any tricks I should know?
Plan to do some kind of cage work down the road, but need bracing early.

cage it before you race it. Period.

Can't afford to cage it ahead of time, Might have a roll bar to start but that is about it. Only 2 of the other races in this class have any sort of cage, and thats because they wanted to remove the doors, hatch, and in 1 of the 2 cases back half the XJ.

Need information on bracing, have access to a CNC and can heat treat, so that helps alot, just give me some ideas.

then there are only 2 smart racers in your class.

but ive never been to PAP so i wont post that.

Well, for bracing, either buy a preformed kit from hdoffroad, T&T, AJs, Ruffstuff, etc or get some steel and measure, cut and bend it yourself, then weld it on. You won't really find any kind of bracing in the junk yard, it's not like any other vehicle came with bracing from the factory, and if it did, it wouldn't fit an XJ anyways. The closest I can think of is the roll bar from a 1st gen 4runner. Not really any bracing, but basic roll protection.

I know the pre formed kits are available, but I was asking if there are any major stress points that I absolutely need to address. I know around the PS box need to make a beasty bracket/brace, but thats the only place I can recall hearing about major issues.

I didn't mean find it in a junkyard, the "if you havent been to PAP, was more of "If you buy all your parts new..." But the 4 runner roll bar is interesting. Would be a good enough start and definately cost efficient if I can find it in the salvage yards.

Hmmm......hard to tell what info you really want. In one sentence you already know everything and in another sentence you ask for advice.

I know there's a lot of fast rough dirt in an ECORS race, and some rocks, how much rock will you be going over? My KOH racing partner runs the ECORS series in the buggy class.

As far as chassis strengthening, here are the weak points that will fail or develop cracks. Definitely around the steering box, but a steering brace won't do it, the frame needs to be reinforced behind the box. The main issue (there are others) is the flexing of the frame between the steering box and the trackbar mount. This area needs plating (including the track bar mount) and it would be good to run both a cross track bar mount brace and a steering box brace AFTER the frame is reinforced in this area.

All of the control arm mounts need to have the seams welded, on the axle weld the inside of the lower mounts, on the frame weld around the outside edges of both the lower and upper mounts. The spot welds won't hold up to competition. Best to plate across the front of the LCA axle mounts. If you're going to run stock control arms, partially box in the bottoms. You haven't said what suspension you plan to run with a 5-6" lift, only which springs.

Frame stiffeners are little help actually stiffening the chassis, they make the frame stronger to resist cracking and denting, but don't add much rigidity to the body. Adding a little thickness to some of the metal doesn't do much stiffening, to add stiffness you need structure, and you only get structure by adding a cage. You can poo poo it all you want, but if you want your car to last and you want to be safe, the only way is to have a cage. Don't argue, just do it as soon as you can. We don't care (and neither should you) what everyone else is doing.

The body will crack (probably first) at the top of the A pillar, at the bottom of the A pillar near the bottom of the windshield, below the A pillar just above the upper door hinge, eventually at the top of the D pillar, at the rear hatch latch on the hatch, around the rear spring shackle mounts, on the rear crossmember around the bumper mount bolts, the rear shock crossmember, eventually in the floor at the rear above the rear shock mounts, eventually at the point where the front frame section meets the firewall, and at both sides of the top of the front most crossmember.

Unfortunately, when only adding stiffness to part of the frame, it makes the un-reinforced sections flex more and increases the rate of metal fatigue and future cracks. Even a simple cage that goes behind the C pillar and as far forward as possible will really help make the chassis more rigid and minimize cracking.

Keep the bumpers light, no need for super heavy duty bumpers. With the super budget way you're going about this, the car might not last that long anyway. Light weight is your friend, it will make the car perform better and put less strain on the drivetrain.

Have fun, that's the idea.

I don't get why you'd run 33's with a welded diff, but 35's with a LSD.......what's the logic behind that? Front axles will hold up better with 33's.

If you can, add some truss or reinforcement to the D30 housing, they bend pretty easily, and add some gussets to the upper part of the inner C's, not very strong on a D30. Also, the 8.8 has 1/4" tubes so make sure the lower shock mounts are well designed to spread the load on the tube. Also weld the tube to the diff, 8.8's can spin the center section.

Consider a PS cooler, small used trans cooler is cheap.

XJfreakHO said:

Can't afford to cage it ahead of time, Might have a roll bar to start but that is about it. Only 2 of the other races in this class have any sort of cage, and thats because they wanted to remove the doors, hatch, and in 1 of the 2 cases back half the XJ.

Need information on bracing, have access to a CNC and can heat treat, so that helps alot, just give me some ideas.

Click to expand...

Can't afford to cage it, but you can afford to race it?

If you can't afford safety equipment, then you can't afford to race.

Look at the T&Js Jeepspeed cage kit - it is a great starting point.

Alright, thats alot of information, I skimmed over it, really good stuff there that Ill have to come back too, have too much going on and about to spend the next few hours in the car.

Just to touch on a few things, I need to update this.

1) Not going to cheap out so much as before, initially this was going to be all about fun for us, was going to try to involve the entire club, alternate drivers as often as possible, so doing it cheap was the biggest priority. We are allowed 3 drivers with the new rules, so thats what we will do, we have to re discuss the entire plan sometime after the holidays.

2) In A class you are allowed either 33's and 1 locker, or 35's open/open. LSD is allowed.
Read up a little this morning on trusses, definately going to put in the time for a d30 truss, and we have the trans cooler, and an extra one that will run as a PS cooler.

3) Sorry for coming across like a dick, I know a basic plan, and I know alot of people are way more knowledgable than I am, and thats why I asked. I just asked poorly and didn't word it well.

I will come back to this later on, thanks for the replies again, excellent information.

Diesel,

Can't afford to cage is wasn't the best wording, was more of caging is not the immediate priority, I was looking at this as more of a lets hurry up and get it together than lets compete, and that was a mistake. With all the holiday pressure Im not exactly thinking rationally, so bare with until about monday and Ill come back with a better description. The idea of ECORS is cheap racing that you don't need to do any crazy work to compete. Cage work is definately in the plan now, but we will have to look into it more, some of the kits Ive seen aren't bad at all so we might look into that.

Again, Ill have to get back to everyone.

I'm really liking the whole concept of cheap racing. We've been racing KOH style, which started fine but has quickly become pretty expensive. Jeepspeed is also expensive to get a car that will perform well and hold together. Now we're doing crap can car racing in an XJ ($500 cars on a road race course), and we're building a rallycross XJ for a customer. Rallycross is pretty inexpensive, $35-40 entry fees and they have stock classes, about as inexpensive as you can get for racing, especially if you use an older XJ.

Pretty cool that XJ's can be competitive in a wide range of racing styles, who would have thought that on old style SUV could really be a good multi-purpose vehicle.

Goatman said:

... who would have thought that on old unibody stationwagon could really be a good multi-purpose vehicle.

Click to expand...

Fixed that for ya...

I'd atleast do a roll bar before racing. I rolled my 96 5 times and am very lucky to be alive. Just remember usually the first place to crush is the a pillar right in front of you.






and a before pic of both my jeeps

That trail looks vaguely familiar. Is that the same trail where that TJ rolled this year?