If you were to build a rock racer.........

Not a moonbuggy, an actual rock racer (xrra style). What would you put in it?

Things that is has to be:

- 2 seater
- good horsepower
- insanely strong suspension components
- fairly tough chassis, not super heavy though
- balanced 50/50 or 40(f)/60(r)
- completely different than anything else out there.

Things to keep in mind:

- I have access to a full machine shop
- I'm a cheap bastard that will spend time waaaayyyyy before money
- I'll be using square tube throughout

I have my own thoughts on the direction I'll be going, but thought it would be good to see what the wack jobs on here can come up with. Oh yeah, it's getting xj skins.

Based on your specifications, heres what I'm thinking.....


1...XJ 2-door body with full tubular space frame. Dont bother trying to make the stock stuff better, just cut out the whole "pan" and start fresh.
2...Vortec V-6, 4L80E tranny, 3 or 4 speed t-case, for the fast and slow sections.....



Mounted TRANSVERLY! :shocked:

3...40 spline Ford 9-inches front (Sunray 609) and rear flipped up-side down (hi-pinion) due to reversed drivetrain.

Think about it....with the engine in the center of the chassis the weight is balanced and it frees up a WHOLE lotta room for front suspension.

gotta start with what motor/tranny and axles you can get cheap, a Vortec V6 to th350, th400 or Powerglide and some HP60s would be great. rectangular tube main rails, 1.5" tube chassis built off that. front engine and put the battery, radiator, fuel cell, etc as far back as reasonable and the engine all the way to the back of the engine compartment. coilovers (not airshocks) and airbumps. rear steer? stuff steering axle(s) with Longfield CVs, detroit front, ARB rear, cutting brakes. Lovell t-case if you're willing to drop the money.

then beat the piss outta it

Light, light & more light. I realize that's a bit of a joke coming form me, but seriously, I think it's THE best way to pick up speed in rocks without beating yourself & your buggy to death.
HP 9's front & rear (for weight & strength).
V6 for short hood with good visibility.
Narrow as possible.

Paul

Wht not find a rolled Tj, lengthen the rails, and attach the Xj to the chassis? Then throw in the cummins, with Dana 70 axles, with some kind of 40 tire, and just lumber over everything. Better yet, outfit it with those trax on each cornner. I doubt there would be very little you couldnt go over!

You guys have rocks in OH?

yeah they are everywhere its amazing. And we can also drive places its unbelievable

I think Sean has in his own backyard!!!!

So are you going to use the motor you picked up or thinking of going another way? If you want weight bias towards the rear I think that little thing will do well pushed rearward. I don't know if I would mate the AW4 to it though. How does it stack up to the other auto's? Weight and size?

Like paul I would be looking for light. Like Bret I think the coil overs would be a better route even at the expense of weight.

Do the 9" housings even maybe some of the lighter ones available with 3/16" tubes, then truss it to handle the beating.

For links I think Crash's idea of building the link instead of tubing. Little thicker on the bottom to take care of the dents. I think that could be built with less weight and tuck into the chassis more than the tube links.

I'm kind of bored with this now so I'll only offer one more idea. Make Pete stay home or in the truck.

BTW, why don't you cut most of the chassis out of billet aluminum.

Currently, I have 4 motors to choose from- sbc 350(mildly built), sbc 305 w/ tpi, efi 302, subaru 2.0 (wrx powerplant).

I've got plenty of axles to choose from too. Most likely I'll be building my own 609's with knuckles made from billet steel. Axle shafts are in question, I don't think I'd be up for affording the long's. Those things are insanely expensive. I could build shafts with motorhome joints, 40 spl, and removable yokes. A 40 spl. arb is insanely expensive though, not to mention 2 of them.

Tcase- I think I'd need a 3 spd. From watching the videos, it looks like the guys that lack gearing really hammer through the technical stuff and it hurts more than it helps. When they get out and need to air it out though, they shine.

The chassis will be made entirely of 1.5" 4130 of varying thickness. Once completed it will go into the oven for the proper treatment. The company we deal with has an oven large enough to pull a full size van into. I can't wait to see the chassis spark when it grinds a rock at night.

Links- I had already planned on making them from scratch. I'm currently figuring out how to make dimple dies and can't wait to start punching holes in everything.

I'd use either the Subaru or the 302. the smaller size of those will allow you to get better weight distribution. the Long's seem like a great deal at $1850 for 1.5" 300m shafts, turn 45 degrees, lifetime warranty, etc, but if you have the ability to go homebrew 40spline, cool. As for gearing, I think some of the guys you're talking about have 2 speed powerglides into 2 speed transfer cases. using a 3 or 4 speed tranny or t-case would probably solve that problem.

Also isn't that AW4 you have the early style with the .705 OD? I was kind of thinking along the same lines as bret. What kind of top speed in something other than high range are you looking for?

If the soccer mom motor is going to give you the big balls you my need I would go that route also. I like the idea of that tiny motor. My only worry would be how broad is the power range. I would think in rock racing you would want something that came on low and kept pulling for a while. That could be fixed with gears but would it top out too quickly?

If I went with the v-8 I would pick which one was the lightest or easy to drop weight from. Both the GM and Fords would be easy. I like the 302 in small stuff. Would definately be fun.

Billet knuckles would make me wet.

One other thought was on the tubing. I'm strenth stupid so it's just a thought. How long to you want the chassis to live without repairs? Several people that I have talked to had smashed tubing on the lower rails after a season. .120 wall chromo. I would think the heat treating would add quite a bit of dent resistance. Since you mentioned heat treating I figure you planning on going pretty thin, I think I would still keep the lower mid chassis rails .120 or even just a capped thinner tube.

For light weight power plants, check out the aluminum range rover V8. Alum block, heads, intake, timing cover, etc. I'd be surprised if the entire motor weighs 275 lbs. In a light weight racer, you still have a killer power to weight ratio. These engines were developed by GM and were in 63-65 Buick Skylarks and Olds F-85s. I had one in my flat fender jeep for a long time, it was a little screamer.

-Dan

i'm also a fan of the Buick 3.8 supercharged V6...

Use a Wankel.
They're lightweight and powerful.
I've seen one in action with 49"s and it never missed a beat. Quick even.

Okie Terry said:

Use a Wankel.
They're lightweight and powerful.
I've seen one in action with 49"s and it never missed a beat. Quick even.

Click to expand...

serious?

what was it from? RX7? I've heard Wankel's have a high and narrow powerband... but that's just what I've heard...

Yeah, an RX-7.
The rig is way low geared and on portals.
It did rap high, but that's just how those things are.
I don't have any action shots, but here's the rig:



This one too, I believe.

If I was building a road racer, I'd contemplate the wankel. It's a prett cool engine. You have to throw them away if you hurt the motor though.

I won't be buying a motor, just using what I have. Same goes for the tranny. I have both versions of the aw4. I'm not really keen on this tranny though as we're having problems with getting the shifts hard. We need to find a way to get the pressure bumped up without using a computer. Time to start digging into the valve body. I've got a couple 700r4's, but I really don't like them.

4ward said:

If I was building a road racer, I'd contemplate the wankel. It's a prett cool engine. You have to throw them away if you hurt the motor though.

I won't be buying a motor, just using what I have. Same goes for the tranny. I have both versions of the aw4. I'm not really keen on this tranny though as we're having problems with getting the shifts hard. We need to find a way to get the pressure bumped up without using a computer. Time to start digging into the valve body. I've got a couple 700r4's, but I really don't like them.

Click to expand...

have you tried playing with the TV cable adjustment to get harder shifts?

I dig the subaru idea...