Help me build a Honda powered sandrail/gokart/dune buggy

[MatobaImportRacing]

I’ve decided that I want to build a Honda powered go-kart/sandrail type vehicle. Basically I want to use street tires to drive both on and off road. To achieve this I would like to use a Honda/Acura front-engine and transaxle to power the rear tires, this idea being provided by Lotus’ use of the Toyota 2ZZ in the Elise. I have a good idea of what I want to do, but very little actual idea of how to go about it. I have never built anything like this before and have a lot to learn, but I believe it will be fun. Basically I would like the rearend to be the same width as a small Honda, a newer Civic of Integra probably. I would like to keep it as short as possible too, but considering the length of the motor/transaxle setup, a seat and driver, pedals, steering rack, and front axles I don’t see this being much shorter than eight feet. It is going to be a one-seater and I would like to use an aluminum floorpan. In addition I would like to modify the front axle to be about four feet long. I have come up with a series of questions that I need answers too prior to building this badboy.

(Most Importantly) What kind of acceleration/speed can I expect? If my reasoning is correct if the whole shebang weighs 600 pounds with me (165 pounds) in the drivers seat and I use a non-vtec B18 (which I have lined up now) that produces about 100 HP and 85 Ft. Lbs. of torque (is this reasonable? I don’t have many much experience with older, non-Vtec Hondas) it should have a power to weight ratio of 1/6 or a 450HP Civic. Does this make sense?

How much would this whole thing weigh, chassis and all?

What is the best way to relocate the shift-linkage, clutch cable, throttle cable, and break lines?

What is the best suspension setup for this type of off-road buggy?

What is the best motor-mount setup? I can imagine that bouncing and jumping a buggy with no real unibody would shear motor mounts really quickly.

What are the heat considerations involved with putting a shifter-kart seat (layback style body is at about a 45 degree angle) a few inches in front the engine?

Where should the radiator be located? Is it possible to run it air-cooled?

Would it be possible to modify the Honda rear-axle to use it as the front axle in the gokart?

How should the steering rack be set up? I assume that turning the front axles would be much easier than the rear, is this correct?

Would a buggy of this size need power steering? Along that line, would the front breaks (in the rear of the buggy) off a Honda be sufficient without front break?

Where should the battery and the fuel cell be located?

What kind of weight bias should I shoot for?

Thanks for all your help in advance. Even if you don't know it would be great if you could point me in the right direction as far as website and/or people.

Also please note that this project doesn't have to be legal for any governing classes of any of that stuff, and it doesn't need to be street legal, so go wild!

[BeEfCaKe]

You might as well just buy a honda and strip everything from it..

There have been threads concerning car motors and go-karts before.. the two simply don't mix..

[Reed]

i dont know much but i think i can help with a few questions.

i think the best suspension setup would be a double A arm in the front (cause it might be easiest to fabricate) but in the back i think you may need to use the honda one.

i highly doubt that you would be able to use teh honda rear axle for the front. probably find a couple if steering knuckes or wheel hubs or whatever they are from the front of another car and mount them to your custom A arm setup.

for steering just use a basic rack and pinion steering, its not going to weigh that much so you wont need power steering and the fact that most of the weight will be on the rear.

shoot for 60 rear 40 front weight but you will probably end up 70 rear 30 front unless you put the battery and fuel and anything else you can up front by your legs

feel free to correct me if anyone has any experience with this cause i dont

[curtis73]

Originally Posted by MatobaImportRacing

(Most Importantly) What kind of acceleration/speed can I expect? If my reasoning is correct if the whole shebang weighs 600 pounds with me (165 pounds) in the drivers seat and I use a non-vtec B18 (which I have lined up now) that produces about 100 HP and 85 Ft. Lbs. of torque (is this reasonable? I don’t have many much experience with older, non-Vtec Hondas) it should have a power to weight ratio of 1/6 or a 450HP Civic. Does this make sense?

What is the best way to relocate the shift-linkage, clutch cable, throttle cable, and break lines?

What is the best suspension setup for this type of off-road buggy?

What is the best motor-mount setup? I can imagine that bouncing and jumping a buggy with no real unibody would shear motor mounts really quickly.

What are the heat considerations involved with putting a shifter-kart seat (layback style body is at about a 45 degree angle) a few inches in front the engine?

Where should the radiator be located? Is it possible to run it air-cooled?

Would it be possible to modify the Honda rear-axle to use it as the front axle in the gokart?

How should the steering rack be set up? I assume that turning the front axles would be much easier than the rear, is this correct?

Would a buggy of this size need power steering? Along that line, would the front breaks (in the rear of the buggy) off a Honda be sufficient without front break?

Where should the battery and the fuel cell be located?

What kind of weight bias should I shoot for?

MY KIND OF PROJECT. Find something you want and then find a way to build it. I love it. I'll try my best with your questions. My strong point is general knowledge, but little of it is based on off-road stuff.

OK, first one; the 450 hp civic. First of all, I doubt you'll be able to have it be that light. I think 1200 lbs is more reasonable. Figure 300 for the engine/tranny, 300 for the frame, 160 for you, another 200 for suspension stuff, gas tank, springs, 13 liters of coolant, 5 quarts of oil... the list continues. The other thing to remember is that acceleration is exponential. To double your acceleration, you need to increase your power-to-wieght ratio by much more than 2. Going from a 16-second quarter mile at 200 hp to an 8 second quarter takes more than just bumping your hp to 400. 8-second times are more on the order of 900 hp. Someone here might know the actual numbers.

2) Clutch, brake, and throttle are easy. The clutch and brake are hydraulic systems, so its a matter of re-plumbing lines. Keep things the same and you should be fine. The shift linkage will be troublesome. You're lucky in one way; the civic's linkage is already cable controlled. If you can somehow find cables of the same strength but long enough to reach the tranny, you've got it made. Put on your fabrication hat and be creative.

3) suspension. Tough one. For the front, you can get a dune-buggy style torsion bar. Its just basically a big bar that you weld in, but inside it are torsion bars. On the outside end is an arm with a spindle. Simple, durable, fool-proof. Add some cheap shocks, and the suspension part is done. The trick is going to be brakes up there. You can order dune buggy axles with brakes, but the chances they will be the right size for the brake fluid you supply them is slim. That's a brake engineering lesson all in itself which I can show you, but not in the area of a forum post The rear suspension is going to give you headaches as well. The easiest way would be to just weld in the civic subframe and use the suspension it comes with. Tempting, but not wise. They are designed for just enough travel on a civic, maybe a few inches up and down. You need off-road kind of travel; several inches. You can't modify the strut suspension for that kind of travel easily. You'll also need different springs... big list there. You'll also have steering to deal with back there. You'll need to find some way of rigidly fixing the steering so it can't turn.

4) Motormounts should be solid, or a rubber suspension bushing. Normal motor mounts would shear, so I suggest either welding them solid or using a fully supported rubber bushing. It consists of a ring (about a three-inch section of tubing) on the frame with a rubber collar inside it, then a steel collar inside the rubber. The outer steel mounts to the frame, the rubber in between, then the motor bolts through the center. No rubber shear can happen that way.

5) Seat in front of the engine. Well, there are several. The surface of the exhaust manifolds can reach 1200 degrees or more and glow cherry red. Not good. The other issue is if you blow a head gasket, throw a belt, or bust a coolant hose, you are wearing it. Four gallons of 230 degree boiling water and steam will be on your head, shoulders, lap, and worst of all; crotch. You don't want to mess with that. What I suggest is mounting it about 6 inches in front and completely isolating the engine with an aluminum firewall.

6) radiator. Put the radiator where you find it most convenient, but not above your head or behind the engine. I suggest running steel tubing to the front and putting the radiator and some electric fans up there. Again, you should separate you from the radiator with a firewall incase of... well, see the crotch reference above. There is absolutely no way of making a water-cooled engine into an air-cooled engine. Different animal altogether.

7) rear axle in front. Yes you could modify it, but way too hard. Do the torsion bar front. The double wishbone/A arm setup like Reed said is a superior system, but its not just something you can throw together and have it be road worthy. There are serious issues with static and dynamic instant centers, roll centers, bump steer... I suggest just a buggy front. Its literally a weld-in.

8) You don't need power steering, nor do you need a rack and pinion. I suggest a junkyard steering box connected from the pitman arm to the spindles with two adjustable rods. Simple, strong, darn close to ideal on a solid front axle. No, you shouldn't eliminate front braking. Its not legal on the street and its not safe on the trail.

9) battery and fuel cell should be up front. In case of either rupturing, they will be far from the engine. They'll also help balance out the car.

10)weight bias. You should always shoot for 50/50 or close to it, but don't worry about it. You'll be way off with the engine in the back. Make sure you have enough weight on the front, otherwise you won't be able to steer. Its not just a case of enough to keep the front down, either. I'm talking; at 30 miles an hour, if you try to steer, it might go straight.

My only other advice is this. Although it doesn't have to be street legal, try to keep the parameters a street vehicle has. I don't have room to go into all of it here, but there are reasons why cars are engineered with a 70/30 brake bias, specific weight distributions, and certain other things. Although it seems like a good design idea to eliminate front brakes, just remember... there's a reason for automakers to spend all that money doubling their design cost, it must be worth it.

[rherbst]

A friend and I built them from scratch some years ago and got in the Three and Four Wheeler Mag. They were awsome in the Oregon Dunes. We used the old all aluminum block 1200 cc honda civic and transaxle. The trans is bullet proof. Strip the car of the rack and pinion steering including steering knuckle and steering wheel mount and tie roads, rear wheel hubs, the shifter, engine and trans, and axels. We did use, originally, the struts but they didn't have the travel we needed. So we went with double a-arm front and rear with hyme joints and used the original strut spring and another shock in the rear and coil over shock in the front. (don't use air shocks) With the engine in the rear, lock the steering arms to the frame. The shifter will be by the driver's seat. Fabricate a steel rod to connect it to the trans. Your shifting pattern will be the same. Use three speed trans. only. Use standard buggy steering brakes and a after market hydraulic clutch. The accelerator was linked by a sealed steel cable. The stock carburation worked originally until the thirst for power took over. We went to four mikuni motorcycle carbs and built a custom intake manifold. We used Dick Cepek spider track atv tires originally. You will need to fabricate wheel spacers from the Honda pattern to the atv rims. Eventually, with the help of a NASCAR engine builder in Burbank Calif. we built a super engine out of the stock 1200cc Honda. We used 1300cc rods, a 1400cc crank, VW valve springs to keep them from floating, and bored the engine. It was stroked and so hot it would blow away a 2135 VW. It ended up being a mid-engine mound and short. The battery was behind the driver's seat along with a aluminum gas tank down low. The radiator, VW rabbit fan cooled, was behind the passenger seat. The exhust ports faced forward and the pipes were bent up and over the engine to the rear like a ski boat. Don't chrome these, coat with black flat powdercoat and they stay cooler and don't rust. We used the original motor mounts, side and bottom. The bottom motor mount was sitting on a piece of dropped square 1/4 x 2 inch square tubing. The side mount was tied into the rear roll cage. This might give you some ideas and I could send some pics..............Dick