Projects Introducing the Roofus Special

A guy on another board did this:

 

I'd offer, but there's a good chance that weeks might go by and I don't find the time or attention and wakefulness. I've printed a hard copy of the above pic, just in case (I work on paper, on a drawing board, you see, and it's useful to be able to start with a tracing.) Let's see.

 

Post the question on the Photoshop thread...those guys work magic!
http://www.jalopyjournal.com/forum/showthread.php?t=300531

 

So what do you guys think the ride height SHOULD be? Right now, it's like sitting in a go kart.

Should I raise it a couple of inches? or embrace the indy roadster vibe?

 

i think the actual height is way to low, maybe take a sideshot of the Roofus and let's see what OahuEli or James D can do with photoshop, these guys (and lots others for sure here) can save you lots a time while trying all the different setups..

btw, i followed all the build, thumbs up, man, great!

Carsten

 

Be practical. Decide how the car will be used. Track time or country roads. Then either make ride height adjustable or build to minimum safe height to get the CG height low for better cornering G's. The lower you sit, the faster it will seem you are driving, and the fewer speeding tickets you will acquire…..
Load the car down in appropriate spots with the weight of two passengers, the battery, and fluids. Then measure heights to the oil sump, the radiator, the frame with all the air out of the tires, so the car is sitting just about on the rims. Add suspension travel of the body/frame going down (get two big guys to trounce on it and see how much clearance you have, front and back…..
Anything that looks vulnerable, add a skidplate or wrap more frame around it.
So, build to function. I laugh to myself when I see cars built otherwise. Women wear high heels for looks, and some break their ankles because of it. I put builders who don't follow function in the same category. What would HAMO (Harry or Ak Miller and Offenhauser) do?

 

I'm with Turbostude on this one! The "Indy" look is great, but unless you plan on putting air bags on it you have to be real careful driving it. I'd look for a minimum of 6" clearance with a load at the lowest spot. That will probably mean 8-10" at the body. That thing is long -- it would look low with 12-14" of ground clearance at the body!

 

There is nothing that sticks lower than the body. The car was designed to be flat-bottomed.

 

Oh yeah, I can't raise it too much either without changing the rear frame. The rear frame goes under the axle. Raising it more than 3 or so inches is going to require a serious re-design.... or some taller wheels and tires.

 

You can always cut a section out and lower the frame under the axle if you have to. You know you'll need a rubber bumper under the axle, unless travel is limited by something other than the frame. I can see you hitting a bump and the back end coming up enough for the axle to contact the frame, especially if you raise it a bit.

 

I think I need to shoot for here fully assembled. The first ground trial, the rear settled two inches.

 

Better to get it figured out now then later, when there will be much more to alter. I wound up with a taller vehicle after coming to grips with some realities of the road..... However, by keeping the heavy stuff down low (battery, engine/trans, fuel) the CG height still stayed low, and lateral G calcs are great. You will also need to decide about the ride character (minimal deflection/feel every bump or easy-breezy long-travel). You can keep it a little tight and fudge with more compliant tires if travel is a big issue, though that's probably a bit of a desperation move.

 

As is, with no shocks, the suspension is pretty soft. My 210 lb self stepping on the drivers side frame tube squishes the car down close to two inches (no real measurement taken).

 

I think it can come up an inch or two. I think you need taller wheels, both for that and for the look and proportions. Perhaps look at lacing those wires to larger-diameter hoops?

A side-on view is becoming necessary now. I'd be inclined not to continue before having spent at least half a day staring at the thing from 40' away.

 

From the looks of things, with a passenger,battery and fuel, you will likely be running out of room pretty quick.... I wound up getting things really stiff. The shocks won't really act as springs when static, but may not allow as much travel when under way. You really can't set pinion angle either till you load it up. That in turn will effect the attitude of the driveshaft, and thus, the hump in the floor..... Also, you need to account for body roll in corners and maintain clearance where the axle leaves the body. If the car is going around a turn and the outside rear wheel hits a bump, clearance on that side is reduced due to body lean to start with. If the wheel then bumps up, how far can it go? Maybe anti-roll bar? It won't stiffen things much, but limit the body roll and deal with some of the trouncing on either side.

 

Not sure whether or not you have seen this page?
http://www.nwvs.org/CarPhotos/CarThumbNails.shtml

Thought it might be of interest - it was flagged up on a UK forum.

LT.

 

Yeah, I've spent many hours drooling over the cars on that site.

 

You should check into running some 18s on that beast. Wires would fit right in with the style of that car and it would get you some ground clearance. Are you able to give us a picture of the side view of the whole car on the ground, or is it too tight?

 

I plan on working on it over the long weekend. I will roll it out for a better picture.

 

Straight-on from the side would be useful. In all my years of sketching cars in this sort of idiom I've found that the proportions tend to be best when the tyre diameter approaches a quarter of the wheelbase. It's a good rule of thumb.

 

The car has a 109" wheelbase.

 

That would be a 27.5" diameter tire. The 215/65R15 tires on my car are 26", a 215/70R16 would be 27.9", 65 would be 27". The slightly taller one would do the trick nicely! A short rubber tire/big wheel just wouldn't look right on that style car, neither would a tire wider than a 215 (which might be a bit too wide @ 8.46"). 205/70R16 = 27.3" (8.07" wide). A 205 16 is about the narrowest you can get at the height you need. I searched Tire Rack for some 195 15 and 16 tires, largest diameter I could come up with was a 195/70R15 (25.7" diameter, 7.68" wide).

 

27¼" tyres aren't all that ambitious. A 225/70-15 will give you that. Tire Rack's website lists twenty types.

A 205/70-16 is skinnier but rarer.

As regards sidewall height, keep in mind that the basic style can conceivably go back to stuff one would expect to wear something like a 4.50x18, so 4⅝" of sidewall isn't all that weird. I'd agree that it'd be all wrong if the tyre were at the same time very wide, but I think one can safely go down to about a 55% aspect ratio if one keeps it skinny and allows for squinting.

 

I have been thinking about these....


Rear tires?

Excelsior Comp V - 700-15

<TABLE class=data-table><TBODY><TR><TD class=att2>SKU: </TD><TD class=att3></TD><TD class=att>587100 </TD></TR><TR><TD class=att2>Cross section: </TD><TD class=att3></TD><TD class=att>9.30 </TD></TR><TR><TD class=att2> Tread Width: </TD><TD class=att3></TD><TD class=att>4.72 </TD></TR><TR><TD class=att2>Overall Diameter: </TD><TD class=att3></TD><TD class=att>28.70 </TD></TR><TR><TD class=att2>Sidewall Style: </TD><TD class=att3></TD><TD class=att>Blackwall </TD></TR><TR><TD class=att2>Price:</TD><TD class=att3></TD><TD class=att>$122.55
</TD></TR></TBODY></TABLE>


Front tires?

Excelsior Comp V - 600-15
<TABLE class=data-table><TBODY><TR><TD class=att2>SKU: </TD><TD class=att3></TD><TD class=att>56465 </TD></TR><TR><TD class=att2> Cross section: </TD><TD class=att3></TD><TD class=att>7.33 </TD></TR><TR><TD class=att2> Tread Width: </TD><TD class=att3></TD><TD class=att>4.58 </TD></TR><TR><TD class=att2>Overall Diameter: </TD><TD class=att3></TD><TD class=att>26.00 </TD></TR><TR><TD class=att2>Sidewall Style: </TD><TD class=att3></TD><TD class=att>Blackwall </TD></TR><TR><TD class=att2>Price:</TD><TD class=att3></TD><TD class=att>$108.54
</TD></TR></TBODY></TABLE>

 

I think it would look pretty good with 700's all around, seems like most of the early race cars didn't run too much rubber rake.

 

I thought you were going to run a bias tire on this car. I think a radial tire would kill the looks of it. That is if you were going for the early open wheeled cars on the 20th century. Bias sould be more period. I know radials are cheaper and better riding, but think about it.

 

I'm pretty sure that is a bias ply tire.

 

It depends on the intention. Radials would immediately identify the car as a modern interpretation of a historical theme, but if it's a good interpretation there's nothing wrong with that. If the intention is a sort of "might-have-been" design in a strict historical idiom, there would be no alternative to crossplies.

Comp V's are crossply, despite the speed rating.

 

I remembered to check a VW Bug site! 165/87R15 is the stock tire (I know, it's an odd series!). 6.5" wide 26" diameter tire. http://www.chircoestore.com/catalog/index.php?cPath=415_416_441&osCsid=70srnr7028hjkp8dlnabomt530.

There are a few others, but the next best one is a 195/65R15 -- 7.7" wide, 25" diameter. I use a 165/80R15 for a "compact" spare for my car.

Those tires run right around $100 each, so not a lot of difference between them and the Excelsior tires. I'd run the same size all around too though. That would be more period correct, if that's what you're looking for.

The only 30s cars I recall with wider tire on the back are some hill climber roadsters. I've seen them with duals on the rear, but still same diameter/size on front. Now duals on the back would be cool looking...

 

there might be another alternative if they are still around. These would be the ones used on the early dually setups on pick ups. there were 215/85 either 15 or 16. might be a bit stiff for this application but the tread pattern looks vintage as does the width and height, around 28 inches.