Off Road Buggy Conceptual

[tinker]

Hey all - I'm a newbie. Back in the day, I had some great times on a friends Honda Odyssey buggy. I think this was around 1979 or '80. This thing had a rigid rear axle and a minimally sprung front end. Anyway, I am planning a 2 seater buggy loosely based on the later Honda's, and I'd like to get some feedback.

Oh, as for a power plant, I have a mid 90's Generac generator sitting around with very little hours. It's a 6500 and I believe it has a 390 or 410cc engine. Anyways, if this is a good choice, I could rebuild the carb and use it.

Any thoughts?

 

[dpaxson]

frame design looks good but hard to make with those bends. the engine is a good size but you're gonna have to make sure it doesn't have a tapered shaft or something so that you can put a clutch or tc on it

 

[tinker]

Thanks for the feedback, dpaxson. I'm thinking the bends may be troublesome too... but I really prefer the fluid look. Have you heard using a HF hydraulic pipe bender and loading the tubing w/ sand before bending? I may try this on some scrap dom tubing laying around the shop. If that fails, I'll likely build a bender and limit the design to a single radius - because of the high-$ dies.

I'll tear into that generator to see what type of shaft it has.

 

[tinker]

Well, it seems that the 13 hp generac engine does have a tapered shaft. That leaves me looking for advice. Should I:
1. Try and locate a straight crank to build in this engine
2. Fabricate a female tapered adapter
3. S**t can the idea of using the generac engine and opt for a HF Honda clone - or even a bike engine

Thanks!

 

[devino246]

I vote bike engine. The rear springs look really long on your design. How long are they supposed to be? Most of the shocks ive seen are 12".

 

[tinker]

Hi devino, you're right... those rear shocks/springs were the last thing I finished late last night. They are way too long for the travel of the swing arm.

 

[dpaxson]

is there enough metal on the shaft to machine a 3/4" straight shaft out of it? if not i think going for a different engine would be your best bet. finding a crank is going to be hard and expensive. i would say sled or bike engine

 

[modelengineer]

For a two seater nothing will work except a bike engine (IMO). The extra weight will kill performance if you're using a 6.5 clone or even a 13hp engine. That ~400cc generator is probably around 13hp, whereas a 400cc bike engine will be more like 40hp, and you get a gearbox.

I'd be looking for something 400cc-650cc. Try to get a single cylinder or a twin because they have more torque at low revs. A 600cc 4 cyl. screamer will not be as quick as a 600cc v-twin in a buggy, even though it has more power. The more torquey engine will be easier and more fun to drive.

*EDIT* a big sled engine would probably work too. I always forget about them because we don't have them in Australia

 

[The_Machine]

keep the generator. they are way too useful

 

[fowler]

im going with model because iv seen two seaters and the smallest one iv seen was a 13hp and it was qiute slow and couldnt really do much

the coolest one i saw had a 600cc that was quite fast on the beach

so i reckon a 400cc would be sensable as a first time progect

 

[tinker]

dpaxson - I doubt it has enough shaft length. I'll have to check this evening. Any idea how much shaft length a TC requires?

Thanks for chiming in model engineer! If I can't easily get this generac engine to work, I'll probably be on the prowl for a bike engine. Although, first I'll have to talk my wife into accepting a shifter buggy. Part of my getting permission for the build was promising that she could drive it. I guess a big 4 stroke thumper from dirt/enduro bike would be the way to go? The wrecked sled would be hard to find down here in Texas... maybe a jetski?

Hi Machine, how are you? Yes, I'll absolutely keep the generator. Funny, I took it home from work back when I owned a construction company. This was in late '99 and it went home because of the y2k scare - just in case the power grid crashed. After that, I never needed it on another job.

Hey Fowler - cool Atom avatar. I'll probably need as much grunt as I can afford... I forgot to mention earlier on that I'm a big guy 6'2"/275. Add to that the weight of my wife, um... no way am I writing down that number.

 

[theo]

Looks like a nice design. If you plan on a engine with weight to it then drop the engine on the swing arm. I think that you will have to place the front a arms in front of the frame, the way you have it shown there the front end will be to wide, ok for a single seat. Also make sure the a arm mounting will match up to the rack.

 

[tinker]

If you plan on a engine with weight to it then drop the engine on the swing arm. I think that you will have to place the front a arms in front of the frame, the way you have it shown there the front end will be to wide, ok for a single seat.

Hi Theo. I'm probably going to scrap this design altogether, as my generac engine has a tapered shaft and is probably destined to be mated to a generator. Bummer! It's ok, it's probably be more trouble than it's worth.

I'm currently leaning toward a bike engine, and therefore want a more aggressive looking - more of a mini-sandrail look.

Those are excellent observations about the buggy suspension design. I initially went with the engine on the swingarm based on most of the Chinese buggy designs. Since then, I've been thinking about all of that unsprung weight. On the new design, I'll probably go IRS - maybe a trailing arm? As for the front end, what you can't see in that side elevation is that the front end is much narrower than the passage compartment - allowing for a reasonable track width.

 

[redsox985]

Just a thread that was around recently but I think before your time.

Independent Rear Suspension

 

[tinker]

Just a thread that was around recently but I think before your time.

Independent Rear Suspension

Hi Sox, thanks for the good read.

 

[redsox985]

Hi Sox, thanks for the good read.

Obviously I'm going to promote my own thread. But it really does have some good info as to which form of IRS is best for your desires.