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Fri May 20, 2011 1:01 pm

OK
Since this seems to be where most of the 36hp LS racers hang out, I thought I would post a few ideas here. Some of you might remember I posted in a earlier post about building a twin engine [36hp] stream-liner, I'm starting to work on the chassis on paper and would like to get some Ideas from some body who's been there. I am thinking about making a basic ladder frame that will have the drivers cage mounted to it, I want to keep as many VW parts as possable so it will have a link pin beam in the front that will be cut down to make it about 6" narrower then stock.
In the rear it will have a IRS trans-axle mounted mid-engine style with shortened axles, it will only have one motor at first but I will build it long enough for two when the time comes. This car will have a pretty basic body on it so I should plenty of room for all the ancillary stuff needed for the car.

As i see it, a land speed car only really has one job and that is too go straight as fast as it can so I would not think it would need a very sophisticated chassis but please correct me if I'm wrong. Let me know what you think of my ideas, I will have some more questions as I go so please bear with me. Thank for any input.

Casey

Fri May 20, 2011 3:03 pm

Keep it simple. The last couple of years @ Bonneville I have seen some very simple designs that work very well. I would look at formula V for ideas for chassis and suspension. Like you said it just needs to go straight. You only need a couple of inches of suspension movement.

Tue May 24, 2011 8:00 am

Using stock VW front suspension will hurt the aerodynamics.

Link Pin spindles on a tube axle would work better.

Tue May 24, 2011 2:47 pm

Unkl Ian
I'm building a stream liner so the wheels will be enclosed within the body and the beam will be out of the air stream. There will only be about 3-4" of the tires exposed under the car.

Casey

Tue May 24, 2011 4:06 pm

I've been thinking about this subject lately, too. In light of the limited horsepower, short course (assuming 130 club venue) and limited expected speeds, I think the most important performance factors for our streamliners will be frontal area, and weight (rolling resistance). Frontal area is going to be more important at lower speeds than aero drag coefficient, turbulence etc. Open wheels, though, I believe would be a detriment even at sub 100 mph speeds. Given our limited horsepower and short course length, weight will be a big factor in acceleration, and traction will not be much of a problem. I think light and skinny will be the ticket. ($.02 taken from the penny dish by the cash register).
Jerry

Tue May 24, 2011 6:07 pm

I would second copying a Formula Vee chassis. Very simple compact design Going mid engined IRS you'll have to design a double A-arm rear suspension like they use on Formula Fords. You're not worried about camber/toe changes so it could be done fairly simply. Personally I would go with 5" shorter swing axles, trailing arms for simplicity and weight reduction.

My favorite T-shirt I saw at B-ville, "Aerodynamics are for people who can't build motors" I laughed, and then I looked at my buggy.....what a brick :lol:

brad

Tue May 24, 2011 7:55 pm

I'm tring to build a car that is only about 48" wide and a over all lenght of about 180", I have a JT aluminum beam I'm going to cut as narrow as I can and use spindle mount wheels to keep the weight down in the front. I the rear I am going to make a simple IRS style trailing arm that will use coil over shocks, I have a set of Datsun 510 axles I'm going to cut down as short as I can. I found a place that sell canopies for home built aircraft that I want to use over the driver compartment, I want to keep the height of the main body about 32-36" tall. I hope to keep the weight down but can't afford chrome moly tube so I'm going have to work on tube placement so it does not get fat.

Casey

Tue May 24, 2011 8:07 pm

slalombuggy
Here a pic of a sticker in the rear window of my Scion XB

I think its less aerodynamic then a VW bug.

Casey

Wed May 25, 2011 9:38 am

Casey,

Before you get to far along on the project you should contact the USFRA and see what they say about the specs you will have to build the car to.

Being enclosed you may have to build it to long course specs even though you are going to run on the short course. I know they didn't want me to build any sides on my buggy between the dash and the kick up at the back as they thought it would impede my exit in case of an emergency. Building an enclosed streamliner might mean full fire supression for cockpit and engine compartment, strict rollcage specs, double lined body in the coskpit area and a bunch of other stuff. Dan Wright is a great guy to work with and will tell you what you need to know.

brad

Wed May 25, 2011 3:19 pm

slalombuggy wrote: Casey,

Before you get to far along on the project you should contact the USFRA and see what they say about the specs you will have to build the car to.

Being enclosed you may have to build it to long course specs even though you are going to run on the short course.

X2 The SCTA has a complete rulebook worth buying NOW, before you draw too many sketches and buy many parts. Many of the old streamliners that used to be legal years ago, are not up to new build standards. I know of two recent examples that had exactly this problem, and the owners were too far along to completely throw the babay out with the bathwater. Think about building a rules legal roll cage and driver safety support surround structure that punches the smallest hole in the air as possible. While still allowing the driver to be somewhat comfortable and see the race course.

Narrow width and VW front beam: I get that you have a free JT beam and free trailing arms, but take a long hard look before you commit to using a VW front beam. The issues are a couple things:

First, when you narrow a T1 beam an extreme amount, the torsion leaves, also narrowed, become extremely stiff springs (spring rate of a torsion leaf or bar is a function of it's center section AND length). I think you want relatively soft on the salt. Every owner that I've talked to with rigid Bonneville cars regret ever have doing that. Some years the Bonneville salt surface is sorta soft and forgiving, others it's as hard as a whore's heart and the rigid cars skiter across the little pressure ridges and bumps, making the car a handful to drive.

Second, the tie rods become so short with respect to the trailing arm length, that bump steer becomes a HUGE issue. Both are problems on Dick Beith's Bonneville VW, that he is going through some pretty creative fixes to remedy. Weather or not they will work as hoped remains to be seen.

Wed May 25, 2011 3:57 pm

Tom and Brad
I have a rule book on the way so I plan to make the car "rules legal".

As for shortening the beam, I'm not going to use torsion bars, I'm going to use coil over shocks that will be tied in to the frame, the beam does not even have shock towers

As for steering it will probably be center load rack/pinion where the tie rod mount in the middle of the rack so they will be as long as possiable, which should help with bump steer, its only going to have about 3" of travel anyways

I want to build the cockpit fully bulk headed and I would add a fire suppression system any ways because I might want to fit a bigger type 1 motor later.

Casey

Wed May 25, 2011 6:04 pm

Casey,

I built a mid-engined, single seater rail years ago for autocross. It had a standard width beam and I used super beetle tie-rods that were just the right length. I would just use a center mount steering box and save the money for a rack to use elsewhere. Cut the tierods to the correct length and run a tap for new threads and you're done. The tie-rods will be of equal length and long enough to dampen any bump steer. The car was 3" off the ground and our parking lots were crap, but I never had any problems.

brad

Wed May 25, 2011 6:31 pm

Here's another setup that minimizes bump steer, and eliminates toe-in change.

Thu May 26, 2011 11:18 am

avus
I had thought about that design after looking at my International Scout, it has the same basic setup as does a Jeep. It work best on a stright axle because every thing moves in the same plane.

SBuggy/Brad
I was a 15 year member of the Las Vegas region SCCA, I started auto crossing a 76 Honda Civic 1200 [man, was that a fun little car] that where me and my buddy got the name "TEAM HUGE' because he was 6'3" 300lbs and I am 6'5" 340lbs. [he passed away a few years ago] I moved on to a Datsun 510 and he had a Scirocco. I always wanted to build a "A Mod" car but never got around to it, after he passed away I could not get back in to auto crossing so now now I'm looking for some thing new.

Before thinking about building a streamliner I was thinking about finding a 84-87 Civic and pulling the motor out of the front and stuffing a 36hp in the back to freak out the Honda guys.

Casey

Thu May 26, 2011 11:32 am

Now I get the "earthquake" moniker :D

I got bumped to A-mod with my big engine, not quite the class to have a 70 year old suspension design in but I have a lot of fun :lol:

We were in Vegas in Feb. Went ot the VW shop on Main St.. Quite the place, they have built some very nice cars.

Honda guys are always fun to PO, a rear engined Civic would be hilarious. Would be even better if oyu did it to a Pregnant Rollerscate 70's vintage Civic. that would have them turning in their graves.....

brad

Thu May 26, 2011 4:35 pm

[quote="earthquake"]avus
I had thought about that design after looking at my International Scout, it has the same basic setup as does a Jeep. It work best on a stright axle because every thing moves in the same plane.

Straight axle might just be the ideal front suspension for a streamliner...

Thu May 26, 2011 6:30 pm

Streamliner, right. I was thinking Lakester. :oops:

Same logic holds, aero is critical for top speed.

If I was doing a streamliner, I would look
closely at what the fast cars are doing.
Guys like George Poteet/ Ron Main, and Rick Vacoucci.

With a conventional front end, it might be able to run
the rear wheels inline, driven by chains off a VW or Porsche transaxle.

Kent Fuller is building a V8 streamliner with a similar layout.

Thu May 26, 2011 6:51 pm

Here is a streamliner called "Yellow Submarine". Short and simple straight axle in the front.

Thu May 26, 2011 8:36 pm

Unkl Ian
The chain drive idea sounds interesting, it sure would make gear ratio changes a lot faster. you could bolt a sprocket on a drive flange and run a live rear axle, with split sprockets you could change them pretty easy. HMMMM

Casey

Sat Jun 04, 2011 1:00 pm

OK
I got my SCTA rule book today, every thing looks pretty straightforward [pun intended] I was expecting it to be a little more complicated, Nothing compared to the SCCA GCR and GT rules, I had a hand in building a GT 1 Corvette once. There are a few things I can't find in it like, is there a minimum weight for stream-liners? can I run spindle mount wheels on the front and if I need to have front brakes. The rules talk about a minimum of 5 lug nuts on the wheels and states "adequate brakes are required in all classes". I assume that since the class I will be building to will be "GS-H" [gas powered stream-liner, H engine class under1.5 liters] I will have to have a parachute but that's ok, makes for higher cool factor.
The record for this class is 268.217 mph, I dont think I will be setting any new records with a 36hp VW motor. How come I dont think this is going to be cheap, O-well I wanted to loose weight anyways.

Casey