Baja hardbody

[HRH]

So it occured to me the other day as I was playing with the 510 that it will never be 4wd. As much as I would like it to be, it will probably remain a RWD group 2 car, whenever I get around to having the money to finish up the roll cage and buy all the safety shit, like seats, harnesses, driving suits, etc.

 

But thinking ahead, and just in general, I've had quite a few hardbodies, and I've always liked them. And my Datsun guru has a VG30 single turbo sitting at his shop that could be bought fairly cheap and of course I started thinking about Baja. I have the Nissan garage poster above my toolbox and I had to go look at it again. Sure enough, mid engine and 4 wheel independent with 380 hp.

 

I was already thinking about this and thought I'd just check google to get some info on how they did that. Yeaaaahhhhh. Apparently that's not on the forefront of everyone's minds this day and age. I found a lot of hardbody extended cabs made into 4x4 desert racers, but none with a four link or better rear and none that were mid-engine.

 

What's more, I was measuring the truck, and with the engine and trans length, I can't see how there would be any room to run a driveline of enough length to allow for massive rear wheel travel. I though about a transaxle design, like sticking a Maxima engine assembly in the bed, but I don't think the halfshafts would have enough travel either, though that would make it independent in the rear.

 

Anybody have any pictures? Any knowhow on that 1986 hardbody race truck? I can't figure out how they did it. For weight balance, it would make a lot more sense to stick the motor in the extended cab portion and make a doghouse to cover it like in a van. And I remember talking with a fellow on a plane quite a while back who raced hardbodies and he had moved his cab three inches backward on frame to get better balance, and he was running front engine.

 

Since hardbodies are becoming relatively cheap now, I'm not opposed to picking up one with a blown motor if I can get it cheap enough, and gradually transform it into a desert-eating monster. Then I'll probably have to move back to Arizona! Or maybe South America! :)

[HRH]

Oh c'mon, no one wants to play? 47 views? Datzenmike, surely YOU must know SOMETHING!!! :D

[nis720]

Here's one I've seen on a KA-T.org and a few other sites. This guy started with a Turbo Z24 then went KA.

 

http://www.cardomain.com/ride/353671

[HRH]

Yeah, I saw that, looks like a lot of work went into it, but he's still using leaf springs on the rear. And it's raked skyward horribly. I don't know if he just hasn't finished the rear suspension or what, but I can't seeing it be desirable for racing with massive travel in the front and none in the rear.

[Duke]

There is a reason that the rear sits low. It is because most of the travel in the rear suspension is in droop to allow the rear wheels to stay on the ground more through rough terrain. The front suspension has more compression travel to soak up the bumps and allow for smoother landings. Also, I don't see a big problem with the leaf springs. They have been used successfully in off road racing for quite some time and a good amount of suspension travel is possible with them. Hell, I would rather have a solid rear axle with leaf springs than IRS (for desert racing that is).

[thisismatt]

I go racing with guys that have a hardbody race truck. It's their older truck and it's been down for a while, but they might be racing it in a couple weeks...not sure. I know I had some pics of it, but I'm not sure where they are.

[thisismatt]

Found a few in my bro-in-law's old album

 

[thisismatt]

And yeah, not a lot of hardbody left in it besides the cab shell and, as required for the class, the frame rails (with a lot of modification/reinforcement).

[HRH]

There is a reason that the rear sits low. It is because most of the travel in the rear suspension is in droop to allow the rear wheels to stay on the ground more through rough terrain. The front suspension has more compression travel to soak up the bumps and allow for smoother landings. Also, I don't see a big problem with the leaf springs. They have been used successfully in off road racing for quite some time and a good amount of suspension travel is possible with them. Hell, I would rather have a solid rear axle with leaf springs than IRS (for desert racing that is).

 

 

No, I agree, a solid rear axle is more desirable in desert racing for sheer strength. At least the long haul hi-flying ones. But having the truck sit way higher in the front than the rear makes no sense. When it's sitting level, that's not droop, that's compression. Looking from the picture it's due to the spring packs, which look pretty stock except for maybe a lengthened shackle. The other thing that's bad about that is the same thing we avoid in our cars. Having low pressure in front going to high pressure lends to lift, which is never good, especially at high speeds in the desert.

 

Thisismatt, nice pics! Any reason they picked the standard cab frame over the extended cab frame? I was debating if weight balance would be better with a shorter wheelbase.

 

Oh, and my roommmate and I were trying to figure out Nissan's design of mid engine and one theory we had was a V6 mid mounted with a transaxle transmission operating longitudinally, thus instead of half shafts to the wheels, driveshafts to each differential. Not sure. Just can't figure out otherwise how to make the space work. Even if you put the V6 right behind the driver's seat, it's still too long to have more than a foot long driveshaft to the rear diff, which just wouldn't work for travel. That thing would bind like crazy I think.

 

I may have to go to the library and see if there's a Nissan book on it. I seem to remember one when I was about 12 at the local library detailing Nissan's impressive early 90s offerings. Before they went almost bankrupt. :(

[Duke]

No, I agree, a solid rear axle is more desirable in desert racing for sheer strength. At least the long haul hi-flying ones. But having the truck sit way higher in the front than the rear makes no sense. When it's sitting level, that's not droop, that's compression. Looking from the picture it's due to the spring packs, which look pretty stock except for maybe a lengthened shackle. The other thing that's bad about that is the same thing we avoid in our cars. Having low pressure in front going to high pressure lends to lift, which is never good, especially at high speeds in the desert.

 

In regards to the use of a solid rear axle, I don't think it is as much of a strength issue as it is a travel issue. Trophy Trucks are running 30+ inches of rear wheel travel, which simply cannot be achieved using IRS and CV joints. In regards to aerodynamics, I think that is one of the last considerations taken in any off road race truck. The static rake of the chassis doesn't matter one bit when you are hammering though a whoops section at 100+ mph. That truck is going to be tossed all over the place.

 

And when I say droop, this is what I mean...

 

Notice that the rear wheels are a good deal lower than the front at full extension. The rear suspension design of these trucks is meant to keep the rear wheels on the ground, driving all the time. If you watch a truck with it's suspension sitting at the lower end of its travel (10% droop, 90% compression) go through a rough section at a fast pace, you will see that it gets jarred around a bunch. Now watch a truck that is sitting with 50% droop and you can see how much better the wheels are able to follow the contours of the ground.

 

Watch in this video how the front wheels skip over the tops of the whoops whereas the the rear wheels follow the contour of the ground much more.

 

[]2eDeYe]

Truck arm suspension is what the big Baja trucks run, like that VW there. It allows for a ton of droop. Leaf springs are cheap and effective though.

 

Get a hardbody, start beating it on some whoops and fix what breaks. You'll have a hard hardbody in no time :D

[hessianben]

wow that VW is Fuuuuugly.

[HRH]

In regards to the use of a solid rear axle, I don't think it is as much of a strength issue as it is a travel issue. Trophy Trucks are running 30+ inches of rear wheel travel, which simply cannot be achieved using IRS and CV joints. In regards to aerodynamics, I think that is one of the last considerations taken in any off road race truck. The static rake of the chassis doesn't matter one bit when you are hammering though a whoops section at 100+ mph. That truck is going to be tossed all over the place.

 

And when I say droop, this is what I mean...

 

Notice that the rear wheels are a good deal lower than the front at full extension. The rear suspension design of these trucks is meant to keep the rear wheels on the ground, driving all the time. If you watch a truck with it's suspension sitting at the lower end of its travel (10% droop, 90% compression) go through a rough section at a fast pace, you will see that it gets jarred around a bunch. Now watch a truck that is sitting with 50% droop and you can see how much better the wheels are able to follow the contours of the ground.

 

Watch in this video how the front wheels skip over the tops of the whoops whereas the the rear wheels follow the contour of the ground much more.

 

 

 

Hmm, can't really see it in that video, but I see what you're saying. I still think aerodynamics come into play though simply because they are going faster than 60 mph in a lot of sections, and even with whoops, that's still going to affect the truck. But mainly I don't like the aesthetic aspects of it. Plus I'm thinking you should be able to design a suspension that sits level but does it's job up high and down low.

 

I'm still waiting for someone to go through their magazines from 1986 and see if there's an article on Nissan's race truck. Still really curious how they managed the mid engine independent suspension. Wish the Datsun garage picture was bigger, can't tell anything from it, except that I want that truck! :)

[thisismatt]

Duke is right. The rake is normal. You'll notice there's less rake on the mid/rear engine buggies/truggies. You want all the up/compression travel you can get on the front for when you slam into whoops or stuff the front end and you have a motor in the way, so you have to get it as far off the ground as possible to get the most up travel. That VW looks like a typical 3 link rear and center mounted A arm front. You just can't get that much travel out of leafs

[ronnny]

Have not been here in awhile and the board has changed. I really do believe in the run it until it breaks and fix and upgrade then. But that is not always the best way to go. Why move the engine to a mid postion. For all the work it would take i would move both the axles forward. If you are going to do a 4 link then it is not much trouble to do at the same time. Work on the bed and move the rear wheels close as to the cab as you can. Then i would get a sfa from a older yota and extend the frame a little to set the axle a little forward. Or if you are 4 linking it then again it will not be that hard to move forward. On the rear i might just go with a trailing arm setup instead of a 4 link. But that is just from my simple way of thinking. If you have setup a 4 link before then it might be just as easy. Then just put the truck on a diet and loose a couple hundred more pounds and you will do alright. Now of corse all my truck building has been older chevy mud trucks. I have not even looked at if the shackles are up or down to think about making a simple leaf setup. A simple 3" yota solid axle lift with a leaf removed for better flex With some nice longer shocks that you can mount at more of an angle so they do not have to have as much travel as a more virtical mounting postion.

[HRH]

I was talking to my Datsun guru today and his question was mid-engine as in the middle of the truck, or just behind the front wheels, as both are technically mid-engine. Alas, I don't have any more information on that race truck and really I'm just curious for the sake of knowing.

[ppeters914]

Kumquat Power!

 

[Eazy_tom]

Check this out

http://www.cardomain.com/ride/353671