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PostPosted: April 29, 2017, 8:22 pm 
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Okay, life got in the way, but I'm back now...

Attachment:
fixed_resized_DSC_6554.JPG


I was working w/ the new Jack-scuttle, and noticed that my front clam shell "hood" was 60" wide (3" between the halves).


Then I noticed that the outer edges on my rear "Cardashians" was 64".

Attachment:
fixed_resized_DSC_6559.JPG


I do recall trying to build in a bit of space for wider rear tires in the future...

Attachment:
fixed_resized_DSC_6570.JPG



Hmmmm....

Then I fitted front tires to the thing, and noticed that the outside edge of the front tires was just a bit wider than the fenders.

Attachment:
fixed_resized_DSC_6568.JPG



Jeez. Dang.

So I guess I need to decide whether to make all of the adjustments to match widths by simply widening the front clam shell, or by a combo of narrowing the rear body work with widening the front clam shell, or... getting creative with the pontoons?


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PostPosted: April 30, 2017, 7:51 am 
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Yo, Tim!
I'd vote for widening the front, at least enough to cover the tires. Narrowing the rear just makes more work, and that you don't need. Also, just like the rear, you may well decide you need more (wider) rubber in the front some day.

You gots Kardashians in the back, lets see some Dolly Parton up front now! :mrgreen:

:cheers:
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PostPosted: April 30, 2017, 11:46 am 
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How about changing the front wheel offset for a cure?


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PostPosted: May 1, 2017, 1:51 am 
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I'm glad to see you back at it, Tim...With any luck, I'll be joining you in that very soon. :cheers:

Unfortunately, it looks like you've got ~6 inches of nose widening to do. :BH:

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PostPosted: May 2, 2017, 2:00 am 
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Tim, what are your front and rear tracks?
Driven5 wrote:
Unfortunately, it looks like you've got ~6 inches of nose widening to do. :BH:
He's already widened it 4".

(Uh, I'm going to improve my question a bit: Tim, what are the outside tire-to-tire dimensions front and rear?)

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PostPosted: May 2, 2017, 11:39 am 
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Well, it looks like he's got another ~6 inches to go.*

A 44" wide (+2) chassis, plus a pair of 205 (typical 15" high performance) tires, plus say a 1.5 inch tire to chassis clearance, yields what I would consider pretty much a minimum rear outside tire measurement of >63 inches. I guess I never thought about it much, but are most traditional Locosts considerably narrower across the front tires than the rears? I know that up to this point I have been planning to be able to accommodate up to a roughly 65-66 inch outside tire dimension, both front and rear, with the front ideally having a slightly wider track than the rear. Even if I am able to go a little narrower at the front, it's looking like I'll have some considerable widening to attempt incorporating on my Lalo nose as well.



*That's what she said.

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PostPosted: May 2, 2017, 11:46 am 
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The rear tires are 63 1/2" outside edge to outside edge. This is based on a 2WD S-10 rear axle with S-10 rims, 195-60r15 tires on it (but the rims are the outside edge).

I note that the front is a full inch wider at 64 1/2". Which is puzzling 'cause I went to great lengths to make sure that they were the same as the rear... but then again, hey, I'm a liberal arts grad not an engineer or machinist or something else that might've been helpful here! I might need to buy another one of Jack's front control arm kits and redo that stuff. I'd like to think that I've learned a bit since I made those things the first time.

But the rear does appear to be the "real" width at 63 1/3". I really can't do more offset (ie, use Camaro rims) w/o doing some MAJOR cutting, etc to the frame, the shock mounting points, etc.

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Last edited by geek49203 on May 2, 2017, 9:23 pm, edited 2 times in total.

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PostPosted: May 2, 2017, 1:12 pm 
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geek49203 wrote:
Okay, life got in the way, but I'm back now...

Attachment:
fixed_resized_DSC_6554.JPG


I was working w/ the new Jack-scuttle, and noticed that my front clam shell "hood" was 60" wide (3" between the halves).


Then I noticed that the outer edges on my rear "Cardashians" was 64".

Attachment:
fixed_resized_DSC_6559.JPG


I do recall trying to build in a bit of space for wider rear tires in the future...

Attachment:
fixed_resized_DSC_6570.JPG



Hmmmm....

Then I fitted front tires to the thing, and noticed that the outside edge of the front tires was just a bit wider than the fenders.

Attachment:
fixed_resized_DSC_6568.JPG



Jeez. Dang.

So I guess I need to decide whether to make all of the adjustments to match widths by simply widening the front clam shell, or by a combo of narrowing the rear body work with widening the front clam shell, or... getting creative with the pontoons?

You don't need to change the track width or the body width, just the camber.
Image
Just like the cool kids are doing. Tire wear probably isn't optimal, but that doesn't much matter, does it? You would probably have the first hellaflush Lalo. Wow, I feel stupid just typing the word, never mind actually saying.
Kristian

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PostPosted: May 2, 2017, 2:49 pm 
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Driven5 wrote:
...a pair of 205 (typical 15" high performance) tires...
My tires are 175/65-15 and I wouldn't care to go bigger. From a weight-to-profile standpoint, 175 width on a 1400 pound car is equivalent to a 375 width on a 3000 pound car (or a 395 on a modern 'Vette, which only has room for 285 on the front). I think wide tires take away the period look of these cars (and similar cars such as the Lotus 11), but if that's what you want to do, I'd say go whole hog and do what people did back when; if you wanted to put late '60s rubber on a late '50s racer, you flared the fenders. I think that muscle motored aluminum Lotus 11 with the flares front and rear looks cooler than cool (I'll try to remember where there's a photo of it, all I know is it attended a British car gathering in Washington a couple/few years ago) and I think a wide tired and fender flared Lalo would be pretty dang neato.

However, widening the nose to fit wider tires isn't going to work without some other mods. As a front wheel rises, it moves inward at the top, and if the nose is widened too much, the top of the tire will contact the inside of the wheel well. Take the spring off the shock and check full range of motion before committing to too much rubber. You may need to add bump stops to keep the tire inside the body without rubbing inside the wheel well.
Driven5 wrote:
...plus say a 1.5 inch tire to chassis clearance...
Close only counts in horseshoes and hand grenades. One must be realistic about compliance, but a half inch of chassis clearance has been sufficient for me.

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PostPosted: May 2, 2017, 4:23 pm 
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JackMcCornack wrote:
Driven5 wrote:
...a pair of 205 (typical 15" high performance) tires...
My tires are 175/65-15 and I wouldn't care to go bigger. From a weight-to-profile standpoint, 175 width on a 1400 pound car is equivalent to a 375 width on a 3000 pound car...
In principle, I completely agree with you. And if your intentions are really only towards 'marketing' the Lalo exclusively to Kubota powered high mpg cruisers, you're probably right. However, when it comes to performance, more than anything else, rubber compound is far and away more important than tire width. If/when my Lalo ever becomes road worthy, it will see track time. And possibly a not inconsiderable amount of it. I don't know about on cars this light, by my experience on mostly sub-3k pound production cars has been that all-season tires not only lack ultimate grip on track, which actually I can live with, they also have considerable problems with melting, chunking, and even delaminating under that kind of abuse...Which is not something that is acceptable to me. I am also planning my tire size the same way I'm planning almost all of my other mass manufactured components...With an eye towards future availability. Not just short term, but mid and even long term. The only size I'd really consider meeting both construction and availability requirements in a 15 inch wheel are the 205/50R15, and to a lesser degree 195/50R15 and 195/55R15, and even those are only 'guaranteed' in the mid-term. Unfortunately though, I'm concerned that tires for 15" wheels may very well go the way of tires for 13 inch wheels within the next decade or so, and where would that leave me if only accommodating an overall diameter and width that then offers absolutely nothing in a streetable sporting compound anymore. That's why I'm actually leaning toward 205/55R16, but would expecting to also be able to accommodate the same diameter but slightly wider 225/50R16 (and subsequently the identical width/diameter to that but much more popular 225/45R17 if need be, someday)...Not because I want to, but because I fear I'll need to eventually.

Yeah, that pic of the 11 with flares was actually mine.

Image

I agree it looked cool, but also does loose some of the classiness (not to mention aerodynamics) that comes from the smooth lines on this bodywork. And while I personally find it an overall visual improvement on the more bulbous Lotus 11, I feel that it would be detrimental to the look of the Lola Mk 1 derived bodywork that we're dealing with. It might still be a last resort option, but if I'm going to do that much fiberglass work building custom fender flares for a Lalo, I'd probably rather assess the feasibility of massaging the inboard side of the front wheel arches a little to accommodate the full range of front wheel motion with the tires I intend to be able to fit.


JackMcCornack wrote:
Close only counts in horseshoes and hand grenades. One must be realistic about compliance, but a half inch of chassis clearance has been sufficient for me.
I'm kind of shocked at this. With my rear upright, and a typical ~.5* camber gain per degree roll translating to ~1* camber gain per inch bump, it's not inconceivable for max bump to produce an inward movement of .75" or more at the the top of the tire, depending on pivot points. Roughly the same could apply to a solid axle at 3 degrees roll, depending on roll center height. Also tires, at least in stickier compounds, are notoriously inconsistent in measured width vs advertised width, namely measuring wider than advertised. I think it has actually become a badge of honor among some tire manufacturers. They're 'under-rating' their performance tire widths in much the same way performance car manufacturers often under-rate the advertised hp.

That being said, if my math is right, a box-stock Miata rear end on a 44" Locost chassis, combined with common high-offset 15" wheels and typical 205/50R15 tires, should result in the vicinity of 2" clearance per side anyways...Which seems to be a pretty common starting point for a Locsost rear end. Of course, it doesn't help that I'm also now looking at passing a suspension arm in the space I expected to have between the tire and chassis based on those measurements.

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PostPosted: May 2, 2017, 9:22 pm 
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JackMcCornack wrote:
My tires are 175/65-15 and I wouldn't care to go bigger. (snip) However, widening the nose to fit wider tires isn't going to work without some other mods. As a front wheel rises, it moves inward at the top, and if the nose is widened too much, the top of the tire will contact the inside of the wheel well. Take the spring off the shock and check full range of motion before committing to too much rubber. You may need to add bump stops to keep the tire inside the body without rubbing inside the wheel well.(more snipping)


Which is kinda what I noticed. I don't want a square "fender" (a la Porsche 962 IMSA GTP in the 1980's) which is what I'd have to do to the clam shell to have have wider front tires. The historical Mk1 photos I've seen have either little fender clearance (the prototype?) or more ample clearance (production?) side to side. In the latter, with the bottoms of the fenders pretty much in the center of the front tire side-to-side and a couple of inches at the top of the fender.

The rear "Kardashians" however, in every historical photo I've seen, seem to have ample space inside of the fenders for wider tires should the become desired.

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PostPosted: May 3, 2017, 12:01 am 
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Good points, Justin. Something I hadn't considered is it might be difficult to find high performance rubber compounds in smaller width street tires. Though for track use, a set of dedicated track wheels and tires seems like the way to go, and 13" racing tires are (and are likely to remain) available in suitable widths, and the smaller diameter will give you a lower CG on the track, as well as allowing more tread width (because the tire won't go as high into the tapered/rounded wheel well).
Driven5 wrote:
...a typical ~.5* camber gain per degree roll translating to ~1* camber gain per inch bump, it's not inconceivable for max bump to produce an inward movement of .75" or more at the the top of the tire...
Right. That's one reason why you need to pull your springs off and check the full range of travel (including full steering lock) before deciding what your clearance is. If you're looking at 1.5" chassis clearance at rest and I'm looking at .5" clearance at full jounce, we may be saying the same thing in different ways.

PS--Justin, thanks for hunting up that Lotus 11 pic.

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PostPosted: May 3, 2017, 6:49 pm 
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JackMcCornack wrote:
Something I hadn't considered is it might be difficult to find high performance rubber compounds in smaller width street tires.
It's far from a perfect capture of all relevant selection data, but here is a little quick reference sheet I put together for helping look at tire sizes, based on the number of tire models available in Tire Rack's current offerings...I even added 175/65R15 for you.

Attachment:
Availability.zip


Attachment:
Availability.jpg



JackMcCornack wrote:
...we may be saying the same thing in different ways.
So it would seem...Which is reassuring for me, that I'm not (totally) crazy. :cheers:


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PostPosted: May 3, 2017, 8:11 pm 
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Rats!
No 14".
My projects tend to 14" rims and probably 205/60-14 if I can find them.

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PostPosted: May 3, 2017, 9:12 pm 
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RichardSIA wrote:
Rats!
No 14".
My projects tend to 14" rims and probably 205/60-14 if I can find them.


With all of the Miatas out there running 14" tires, I think that someone will have "performance" tires for the rest of our lifetimes?

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