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Stage rally truck prep - need opinions

That comanche Is SWEEEEEEEEET! man. I like seeing a Jeep fly down the road then suddenly slamming on the brakes to whip it around a corner! :D
 
Not a lot more expensive = twice as much? Is it really worth double?
I was talking about the single tube 7100s, not the remote reservoir shocks. The pricing I've looked at have the 7100s in the 130-150 range and the 5150s around 100-110. (yep, the RR 7100s are 190-200 :eek:)
Are they worth it? They have similar sized pistons, so with equivalent valving, they'll be about the same on the course. The 5150s might be a little more fade resistant due to the fixed reservoir/higher oil capacity.

I think the advantage of the 7100s is the retuneability. If you don't like the valving of the 7100s, you just change it. Also, if something breaks, you can get parts. With the 51s, you buy new shocks.

If I was doing it, I'd spring for the rebuildable shocks. On the flip side, everyone here who's got 5150s love them.

My experience(limited, I admit) is with desert racing. The the theory there seems to be: beef up everything, and spend as much money as you can afford(+20%) on shocks.
By the way, here's what we do: Derrick drives and I navigate.
race7118.jpg
 
Credit where credit is due: It's Zoomy97acr's.(that's Derrick's) truck.
'88 long bed MJ, 1.75" full cage with the rear supports running down to the front spring perches. Ladder frame/tire carrier/etc mounted in the bed carries the structure back to the shackle hangers - that stiffens the whole truck up.

Stock basic engine(4.0) with a header, converted to an open cooling system. We use a custom oversized air filter to deal with dust. You probably don't need to bother with that.
It's currently 2WD automatic.(AW-4) with a BIG transmission cooler.
Rear axle is a Dana 44, 4.56 gears and a spool. The axle is trussed pretty heavily both side to side and fore and aft.
Currently running 33" BFG Bajas on 15X8 aluminum rims.
Stock brakes F and R, with the load sensor switch disconnected and wired up.
Suspension:
Front: Stock arms, Trussed 2wd axle, 3" lift springs(I'll have to call Derrick for the specs, but they're too light. We're going to a higher rate spring) Fox 2.5" remote reservoir 12" travel shocks (our class is limited to 10" front travel)punched up through the fenders and mounted to a cage oveer the engine. We run the factory antisway bar, with the factory links. In Parker, we busted the driver side link, and had to run without it(which is why I highly advise you keep the sway bar:D) Steering is all bone stock.
Rear: Deaver springs, about 3" lift. No rear antisway bar, but there are dual "anti-wrap" bars that act to limit unequal suspension travel(they're supposed to prevent spring wrap, which they also do well) Fox 2.5"s again, 14" travel, I think. The shocks are through the bed, and mount to the ladder truss in the bed.

32 Gallon fuel cell, mounted behind the axle, and sunk in the bed about a foot. Electric pump and remote filter mounted in the bed.

Most of the interior stuff wouldn't apply to you, but but this might: If you look at the pic close, you can see the engine gauges are aimed at the passenger seat. The driver only has the tach. and the speedo. to look at. If you hav a co-driver/navigator, put him to work watching the needles while you concentrate on driving.

Another thought just occurred: you said you hang up and drag the rear bumper. If you have the stock fuel tank, you might want to get a factory or aftermarket gas tank skid. It would protect the tank and add weight down low in back where you need it.
 
The easiest way to make power would be to remove any unneeded engine driven accessories, over bore cylinders for an increase in compression (increased up-swept volume), leave head deck surface alone unless its untrue, CC combustion chambers and intake/exhaust runners. As long as the compression ratio isn't to high you might be able to zero deck the block. Then camshaft and lifters, larger valves, valve spring and retainers from Hesco. Clifford intake manifold, and a two barrel or small four barrel carb. Your choice of header, mandrel bent exhaust with high flow muffler. HEI ignition from DUI. Swap in an AX-5 instead of the AX-4. Spool out back with a set of 4.10's or so. You're still looking at dropping some serious dough to be pretty competitive.
 
...,Stock brakes? What do you run for shoes?
Yep, stock brakes. :shocked: I think he's got Mopar pads(he's a dealer mechanic) I should mention that we've had brake failures twice now due to the fluid splashing out the top. 'Can't seem to keep the cover sealed when the truck gets bouncing hard. :D
We definitely need a full array of gauges, since all I have is a shift light (no tach).
We run engine temp, oil pressure, and voltmeter. He has a big-a** tach on his side.
I'd be interested to know your spring rates. And I would kill for a 32 gallon tank....
I'll get with Derrick this weekend and see what info he's got on the springs. That fuel cell was in the truck when he bought it. We have a spare that we got off Ebay for about $450.00. I like the idea of a fuel cell, but if your rules don't require it, you might want to spend money elsewhere first.
Here's a tip for adding a little more gas to the stock tank(like 4-5 gallons).
http://www.go.jeep-xj.info/HowtoFuelTank.htm
Gojeep is a member. Check out the rest of his site, there's a lot of stuff you could use.
http://www.go.jeep-xj.info/
 
Best single (and most expensive) idea seen here... Late model 2.4 and a 6 speed. Barring that, how about swapping in pre-OBD2 2.5 MPFI motor and computer. Yes, I know it isn't compatible with the 86 directly, but if you snagged a whole XJ you'd have everything needed. No matter what you use, let it breath freely.

Suspension, you are more concerned with compression and rebound, not droop. Budget says, those urethane bump stops in the springs will work. I might suggest ZJ upcountry coils for a firmer ride and small lift. Also use the V8 ZJ steering parts and the ZJ front swaybar. At least have it on the trailer for tuning. I like the idea of just a little lift, firmer springs to keep the tires out of the fenders. Shocks, something you can tune. Use some slightly taller shackles, not so much for lift, but to allow the springs to move a lot more.

Bigger brakes... 8.8 Ford Explorer with discs. Easy to find and easy to swap. Front 2WD axle with WJ knuckles for those massive Akebono brakes. Do the spacer mod (JKS I think has the spacer) to allow the use of standard 5x4.5 4WD unit bearings and redrill the WJ rotors (maybe have a couple spares on hand just in case!). Use a broken stubshaft to hold the unit bearings together. Maybe keep a couple spares ready to swap in in case of bearing failure. As mentioned a better mastercylinder, consider hydroboost. Maybe an adjustable brake bias controller in the cab... (and as soon as I find some Akebono brakes, I'm doing that mod for my ZJ HPD30 I'm slowly building...)

I think the longer wheelbase you have is a good thing, shorter rigs would swap ends too quick, the longer wheelbase lets you have a bit more control. At least the way I drive...

Just my opinions...:passgas::explosion
 
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Just a thought here, what about the 2.8 litre chevy motor that was factory installed back in the middle to late eighties? It was the first version of the 3.1 and then the 3.4 litre engines...Kinda makes me wonder if the internals interchange :shhh:
 
IIRC, the power output of that v6 was pretty blah, and compared with the 2.5L, so I don't think it would be worth the time/money for the swap. If anyone has a better opinion, feel free to share.
I was kinda thinking 2.8 litre block. 3.4 rotating assy, milled heads to up the compression - I know Comp Cams lists some cams for these. Some headers and maybe a Holly 4412 if rules allow...Gotta build pretty good power, I would think? Almost 1.0 litre bigger, and would be pretty hard to detect unless they pulled the entire motor apart...
 
Not sure if it would be worth the risk, I know where I use to race, (completely different type of racing though) They would only tech the top three in each class. If you refused, the worst that could happen was you could loose your points for the night. When I first started, We did everthing by the book. After doing it for a few years, started realizing EVERYBODY was doing little tricks like this. Made it hard to compete unless you did the same...I cant speak for your class though...
 
If I wanted to quicken up the steering ratio a little, is there a simple trick for that?
Find a longer pitman arm then the one you are currently running. Chrysler did that with the 'Cuda/Challenger in '70 from the factory. The "quick ratio" steering consisted of a different pitman arm.

With the Jeep, you're limited to how far back the drag link can move without hitting the track bar, etc. Also, there may be issues with the tie rod hitting the sway bar mounts. The good news is with a 2wd, at least you don't have to clear the front dif.
 
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