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_
_ Reader
3/23/19 6:11 p.m.

First off- “is it legal”? As in, “Will most sanctioning bodies allow one to run”? Not for road legality, I know how to get around that. 

Second- how do I make it handle? It’s going to be Bug suspension, so I guess I should look into that. Is there a VW bug suspension kit for IRS?

Patrick
Patrick GRM+ Memberand MegaDork
3/23/19 6:16 p.m.

Look up jthw8’s “lot lizard” 

_
_ Reader
3/23/19 6:21 p.m.

Ok. Here’s the one I’m thinking of: https://m.facebook.com/marketplace/item/1267624010084067/

it says “irs bug” suspension. But I wonder if it’s that awful swing arm stuff. I know literally nothing about bugs. Or ancient VWs for that matter. 

SkinnyG
SkinnyG UltraDork
3/23/19 6:59 p.m.

I think dunebuggies end up in B/Mod?  Is that still the case?

Woody
Woody GRM+ Memberand MegaDork
3/23/19 7:20 p.m.

I’ve wanted to do this since 1986. 

Knurled.
Knurled. GRM+ Memberand MegaDork
3/23/19 7:27 p.m.
_ said:

First off- “is it legal”? As in, “Will most sanctioning bodies allow one to run”? Not for road legality, I know how to get around that. 

Second- how do I make it handle? It’s going to be Bug suspension, so I guess I should look into that. Is there a VW bug suspension kit for IRS?

Don't you basically make them handle by lowering them as much as possible, then try to keep the suspension from moving very much up and down, and run a Z bar (kind of a pro sway bar) in the rear?  Assuming swing axles... not sure if IRS buggies exist.

 

IRS buggies should handle like really, really nose-light 944s, no?

_
_ Reader
3/23/19 7:57 p.m.

In reply to Knurled. :

I dunno man, you tell me. I’m gonna try and mull it over. It would be some work, but I’ve also considered making one into a street legal, autocross, rallycross thingy. 

Knurled.
Knurled. GRM+ Memberand MegaDork
3/23/19 8:04 p.m.

In reply to _ :

I can't speak for autocross but back when they were legal for rallycross (they kind of aren't now) they suuuuucked at rallycross.  Way too much unsprung weight to sprung weight ratio, they'd bounce all over the place and have trouble even moving in a straight line without swapping ends, and they didn't like turning much either.

Ian F
Ian F MegaDork
3/23/19 8:21 p.m.
Patrick said:

Look up jthw8’s “lot lizard” 

Here is a link to the build thread.

And the for sale thread a year and a half later.

I miss Jim's posts. sad

buzzboy
buzzboy HalfDork
3/23/19 10:26 p.m.

IRS bugs, MY68 and up US delivery, use trailing arms rear and front. There is zero camber gain through suspension bump which isn't great. Swing axle bugs, MY67 and early or Mexican built, use the swing axle rear. I've ridden in a nice lowered swing axle street rail and it was really fun, but I don't know how well it actually handles as we were just out drifting.

Knurled.
Knurled. GRM+ Memberand MegaDork
3/24/19 8:44 a.m.
buzzboy said:

IRS bugs, MY68 and up US delivery, use trailing arms rear and front. There is zero camber gain through suspension bump which isn't great.

 

The problem with the swing axles though, and the reason that VW stopped using them (and why Chevy got crucified over the early Corvair), is that the roll center ends up being extremely high, like 3-4" higher than axle centerline high, which is dangerously close to the center of gravity height..  And the roll center moves around a lot with suspension motion.  So you have a suspension that already is extremely resistant to motion in roll, in the rear, in a rear-heavy chassis (not great), and then if you go over a crest or lift off the throttle (already a bad idea in a rear engined car)  the roll couple can actually change signs with the roll center being HIGHER than the center of gravity.

 

When the roll couple changes signs, the suspension wants to lean "IN" to the turn.  But since the CG is above ground level, the car won't.  The outside suspension just extends.

 

This is swing axle jacking.

 

The IRS suspension, with its roll center basically on the ground, will be an altogether better handling vehicle, and less violently sensitive to suspension motion, since the roll center barely moves and it is a better place to begin with.

Jim Pettengill
Jim Pettengill HalfDork
3/24/19 10:33 a.m.

A buggy chassis can be made to handle pretty well, but it's not easy.  Study a Formula Vee and go from there.  Don't expect a nationally competitive car, but they can be made to work.  I'd favor an IRS rear, a balljoint front end for adjustable camber, pay attention to weight distribution (battery, etc) and soften the front torsion bars so you don't get terminal understeer.  If it's a swing axle rear, you'll have to decamber and do something to limit jacking - some sort of compensator device or a Z-bar (probably a little tough to go all the way to a FV-style zero-roll rear setup, but study them, they work for road racing).

DeadSkunk  (Warren)
DeadSkunk (Warren) PowerDork
3/24/19 11:04 a.m.

I autocrossed a retired Formula -Vee many years ago. For the buggy in question , I'd look at making it mid-engine if there's enough room behind the seat, lower it with an adjuster in the front beam, replace the upper front spring pack with a sway bar, shim the front trailing arms to get some camber, replace the rear swing arms with longer ones to reduce toe changes. If it's a swing axle, then a Z-bar is needed. Will it be competitive?......Not likely. Will it be fun?...... Oh! Yes !!.  I gave up on using road racing slicks at the time and switched to the best available DOT tires. Those were Yokohama A001Rs ( I told you it was many years ago !) and they worked better because they didn't require heat to work like the slicks did. I subsequently sold the car to a college student who used it for a college project. He created an envelope body for it and licensed it for street use.

_
_ Reader
3/24/19 11:11 a.m.

So In reply to DeadSkunk (Warren) :

So I’ve been doing some reading, and I think I can pick up a cheap 88-91 civic and harvest the whole front end. This would give a mid engine car, Honda reliability. SUPER cheap Ecu and efi. Double wish bones. But the question then is how do (easily) I get double double wishbones in front also? A macstrut setup would be simplest, I guess. But maybe harvest a Miata and create a “not hack jobbed” ghettocet?

like this: https://www.autoxandtrack.com/bugzilla-mid-engine-autocross-vw-bug/

pirate
pirate HalfDork
3/24/19 11:39 a.m.

One of the biggest problems with VW powered dune buggies is the front ends are so light they push (under steer) really bad which is complicated even more because they use small narrow tires in the front. Last year at Cruisn the Coast in Biloxi Ms I saw a neat mid engined buggy with  2.3 Pinto engine completely set up for the street. Owner said it handled very well. Also said the Pinto was around 200 horsepower that was done quite cheap compared to the cost of trying to get that much horsepower out of a VW. Didn’t pay that much attention to front or rear suspension so can’t offer much. He did say the mid engine Pinto setups were fairly common. 

_
_ Reader
3/24/19 12:18 p.m.

A lot of weight could be allocated to the front. Battery and fuel tank and radiator come to mind. Also, a Miata front suspension would add weight to the front as well. 

Iusedtobefast
Iusedtobefast Reader
3/24/19 1:17 p.m.

Berrien makes a chassis that has the seats further forward to shift weight forward. Our old short course buggy we raced was based on it. Never drove it in anger on pavement but the shift sure helped in the dirt. 

Racingsnake
Racingsnake New Reader
3/24/19 1:18 p.m.

Pick up a copy of May '71 Dune Buggies & Hot VWs. There is an article on setting up a buggy for auto cross featuring Alex Dearborn's Deserter buggy which was apparently pretty competitive. I'd imagine it should be pretty applicable to a sand rail.

DeadSkunk  (Warren)
DeadSkunk (Warren) PowerDork
3/24/19 1:38 p.m.

By the time you modify this chassis to accept Miata front and Honda engine/trans/suspension rear you will have paid $800 for the chassis. I'd think about building my own at that point, maybe. The VW chassis looks like you could modify it fairly easily though. Buy it and see. No one here is going to tell you not to.

Kreb
Kreb GRM+ Memberand UberDork
3/24/19 1:57 p.m.

I can't speak to classing, but in terms of unadjusted times, a buggy can be decently quick at auto-X. A guy used to run one in my region and would be roughly 75th percentile unadjusted. He'd lower the car as far as he could, throw fat tires on and go. Porsche, Fiat and Abarth have made some damn fast rear-engined autocrossers.    

Ovid_and_Flem
Ovid_and_Flem SuperDork
3/24/19 2:22 p.m.
Racingsnake said:

Pick up a copy of May '71 Dune Buggies & Hot VWs. There is an article on setting up a buggy for auto cross featuring Alex Dearborn's Deserter buggy which was apparently pretty competitive. I'd imagine it should be pretty applicable to a sand rail.

48 year old technology!   Gotta be fast... cheeky

Apexcarver
Apexcarver UltimaDork
3/24/19 2:43 p.m.

If anyone wants it, I'm trying to get rid of some miata suspension bits.

A 401 CJ
A 401 CJ GRM+ Memberand Dork
3/24/19 3:11 p.m.

Allegedly a Meyers Manx could be made to handle extremely well.  Wouldn’t that have a “bug” suspension set up?

ronholm
ronholm Dork
3/24/19 3:23 p.m.

If I were building one and confined to bug parts/design it would be built with 67+ ball joint front end and IRS suspension.    Widening the Ball joint front for street use would be easy, and then "3x3" trailing arms designed to move the rear wheels 3 inches further back and out.     

up front though with a blank slate and nothing but tubes there are lots of better options than bug parts...  and the days of cheap bug drivetrains are nearly over, so using a fwd setup back there seems cheaper.....            

JohnInKansas
JohnInKansas SuperDork
3/24/19 4:41 p.m.

In reply to Ian F :

Did I miss something? 

Jim talked me into building my Beetle yhe way I did. I've been wondering if he was still around.

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