Making an XJ into a rally car?

S

SeanP

NAXJA Forum User
Location
Rocklin, CA
Those that know me know that I would love to drive rally sometime. Their is a series in CA and NV (CRS with two sanctioning bodies, Rally America and NASA). My dream is to run a turbo AWD like a WRX/EVO type rig. However, rules say you can't start with a turbo rig like that.

Some folks are building FWD honda's, VW's, etc and starting there. That would be great, but I don't have any interest in starting way down the learning curve with a rig that I won't have very long. Basically, it would be the equivelant to going back to 1998 with my XJ knowledge.

In looking at all the vehicles that folks "run what they brung" at these events, I thought "Why not an XJ?" :idea: I already know everything about these rigs. I know how to build a cage and strengthen the weak points of the unibody. Here's the pros:
Pro's
Torquey 4.0 with reliable AX-15.
Cheap to find a mid 90's two door 5SP with a lot of miles
Easy to regear to 4:10s which with 29-30" tires would be ideal at keeping the torque curve in the sweet spot.
I already know how to build a cage
When/If I move up to a WRX-type car, I can reuse the XJ chassis for a rock crawler or sell it for a JeepSpeed rig.

Con's
Solid axles front and rear would give up some stability.
Questionable brakes. (not sure what the rules allow for disc upgrades)
Weight, although a 2 Door stripped should be able to get to under 3000#.

Any thoughts on this? I know it sounds crazy, but I just don't want to have to relearn a new chassis for a year or two, only to move onto a turbo subaru.
 
If it we me, I'd lower it a little, and get the biggest sway bars possible with some HUGE shocks. The biggest problem you'll run into is body lean(due to the high COG), by the way that dude with the honda is gonna kick your butt, FWD, high rpms all the time, low center of gravity (etc). I think you'd wind the crap out of a 4.0 trying to keep up with those high rpm motors.
 
I think it's doable. Your going to have to watch the weight though, but the honda's and vw's can be that much lighter. Find a XJ with the full-time four wheeldrive. Drop it a few inches. You could run wheel spacers if you wanted more stance. I don't think the solid axles will be that big of a difference, ride might suffer but thats what shocks are for. Get some good ones, Walker, Fox, ect. Can you run air bumps?

You don't have to keep up with the honda's high rpm's, you just have to keep the speed. I'd look at/try 31's if they would fit, more sidewall, bigger contact patch. Sawybars would need to be upgraded, depending on how you want it to handle, but might want the rear bar to be stiffer then the front.

Brakes could be an issue, maybe another vacuum booster or hydro boost? What are the rules anyways?
 
Just yesterday I was thinking to myself, "that SeanP needs another project." :D
 
CRASH said:
Just yesterday I was thinking to myself, "that SeanP needs another project." :D
Click to expand...

:) Yep, that's me.

looking at the rules more closely. Different mods will bump you up classes. I think keeping the rear stiffer and making it under steer a bit would be preferable. I would rather have torque than HP, so the honda's don't scare me too much.
 
I like it! What do the rules say about removing glass? If you can get rid of all your glass that would lower the COG of course. Can you chop the top like some people on here do? If you are going to build a cage anyway, that would help save some weight.

I've had the same thoughts myself; seems like a slightly lowered and stripped XJ would make a fun rally car, especially if your mods allowed you to stay in one of the lower classes to be competitive.

If you lock the rear; you will have all the oversteer you want, on command with a touch of the throttle. Sounds like you already know this though.
 
Weasel said:
having the rear stiffer will create oversteer, front stiffer will give you understeer.

What about an auto with one a brett's paddle shifters?
Click to expand...

I always name them wrong, I want to be able to break the rear loose before the front.

I am pretty nearly sure that I want a manual tranny.

Gotta have a windshield. If I pull the glass, I gotta have nets in front. I really think with a stripped interior, I could be looking at 2850# or so. Plus my fat ass ;)

I will probably want to put a wrap bar in the rear and then find/make some stiffer sway bars.

242, I wonder how the viscous coupler would hold up. would be cool to play with the coupler and change the rate of engagement.
 
Could you remove the rear glass and replace with lexan or something along those lines? That would cut the weight down a bit.. and more importantly lower the COG a bit. Lower it a couple inches, backspace the wheels a bit to get a wider stance. Whatever you do, I want to know how this turns out. I always wondered how a XJ would be rallying after I bombed around the cranberry bogs in my camry, then went Jeep and did it in the stock XJ and it did quite well.
 
SeanP said:
I always name them wrong, I want to be able to break the rear loose before the front.
Click to expand...
No your right, having the rear come around is oversteer. You can just the engine power to break the wheels loose and induce a power oversteer, but thats a little different then oversteer/understeer. Generaly if the front is stiffer you get understeer and if the rear is stiffer then you get oversteer. You can get a poly windshield. Speedglass would make me one but I would have to buy a glass one for them to form it over as they don't have a mold. That would be a good group deal to get some poly windshields made and split up the cost of the glass form. The rest of the glass should be able to be swapped with poly pretty easily.
 
Can the jeep speed guys make use of poly windshields? If so, then that would make an interesting ploy for a group buy.

I am wondering if a set of poly bushings would be a good decision? Plus some sort of upgrade to the track bar mounts/rod ends. Plus steering.

Maybe what I really want to do is jeep speed, but I am more interested in turning, steering and braking skill than just balls-out high speed desert whoops. The plus of my plan is if I bail from rally or upgrade, I will have a chassis I can sell pretty easily and I won't have to acquire knowledge about a ricer car that i am not really interested in fielding long-term. Dangeroursly close to non-tech here, but this is the group to tell me if I am totally wacked.
 
The 249 uses a viscous coupler, the XJ 242 uses planetary gears for the full time position, from what I understand.

Seems like the 242 would be the best choice for the rally car because you could still choose between 2wd, 4wd, and full time.
 
zthang43 said:
The 249 uses a viscous coupler, the XJ 242 uses planetary gears for the full time position, from what I understand.

Seems like the 242 would be the best choice for the rally car because you could still choose between 2wd, 4wd, and full time.
Click to expand...

aparently its a manual clutch, set up, not viscous, not planetary

but yes the 242 is better
 
tealcherokee said:
aparently its a manual clutch, set up, not viscous, not planetary

but yes the 242 is better
Click to expand...

Teal,

I :worship: to your superior knowledge of performance tuning, but...

The NP242 uses planetary gears!
No viscuous couplings, no clutches.
 
You must log in or register to reply here.

Similar threads

tmbuster
Back in an XJ finally!
Replies
0
Views
55
tmbuster
tmbuster
S
96 xj diesel swap
Replies
7
Views
223
silverpearljku
S
J
96xj trans in an 89xj
Replies
2
Views
186
Black1990jeep
B
R
Random Hard Start, Low Power
Replies
0
Views
46
rtd16
R
M
Correct rim size for a 265/70r17 tire with a 4” lift
Replies
10
Views
203
75SV1
7
Back
Top