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PostPosted: September 8, 2016, 8:01 am 
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Joined: January 9, 2016, 8:45 pm
Posts: 53
Location: Knoxville, TN
I honestly thought I had already posted these questions yesterday but I guess I did not. Sucks not being able to remember things from day to day.

So I am about a month away from starting to work on a rolling chassis I bought and I have a few questions.

How tall of a tire seems to be the norm? I have been using 25" as the height when calculating speed, RPM and gearing needed. 25" seems about perfect for my C4 automatic with 2.79 rear end gears. I have a set of used aluminum wheels I picked up for CHEAP that I will be using for mock up. Because they are lightweight I might actually drive on them. The wheels are 16" tall and 6.5" wide.

What is a common steering column? The steering setup that came with the car is a basic setup without any turn signals. The biggest reason I want to replace the one that came on the rolling chassis is it is solid and will not collapse. So I want to change the steering column so I do not skewer myself if I get into an accident. And with this thing eventually being driven on the street I need turn signals and there is no easy way to install those using the current steering setup.

And one final question. I plan on using separate master cylinders for the front and rear brakes. The front use GM calipers and 11" Granada rotors that are neither drilled or slotted. The rear brakes are stock rear disks from a 1998 Mustang, they too are not drilled or slotted. I prefer a stiffer pedal without a lot of travel. I am hoping the car will weigh in under 1,500 pounds with me in the car. So what bore diameters would be a good place to start? Or would a single master cylinder with dual outlets be better?

Thanks


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PostPosted: September 8, 2016, 9:19 am 
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Joined: June 15, 2010, 8:29 am
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Location: Duxbury, MA USA
I think most are running a smaller tire diameter than that. Mine is 23 inches. I dont think a 25 inch will look crazy though. A lot if this depends on your suspension setup. You should see what your suspension does before committing to your final tire size and wheel offsets. Getting a great steering feel is one of the big joys of these cars if its done right.
The Miata steering column is probably the most popular as many of the cars are Miata based. Although mine is not a Miata based car, I used a Miata column. I was able the get every control onto the column without having any other switches in the car.
As far as brakes go, dual cylinders is a good choice as if you want to change the balance beyond what you can get with a balance bar its pretty easy just to change the bore. You also have to decide if you are going to use a vacuum assist if you go with factory master cylinders.

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PostPosted: September 8, 2016, 2:15 pm 
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Joined: April 26, 2008, 6:06 pm
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Location: Under the weather. (Seattle)
Tires: 23" is probably most common for Locosts, but 25" is far more commonly available.

Steering column: What you have is also pretty commonly used in Locosts, and racecars. There are collapsible steering shaft segments that can be added. A properly implemented two piece shaft should also significantly help in allowing the forward section to deflect rather than sending the forces straight up to the steering wheel. Turn signals can be as simple as a toggle switch on the dash, but there are also 'hot-rod' turn signal switches that can be used as well. Neither would be self-canceling, if that's important to you.

MC Sizing: viewtopic.php?f=5&t=14424

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PostPosted: September 27, 2016, 3:05 pm 
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Joined: May 27, 2006, 9:46 pm
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Location: BC, Canada. eh?
My tires are 205/50-15's, and 22.5" tall, if that helps.

As far as the steering column is concerned, I wanted something fairly simple, but I also wanted tilt, to make ingress/egress easier (many of these cars are tight to get in & out of - having a couple more inches via a tilt column is a big help). I looked at a hundreds of steering columns, and ended up with one out of a late-80's Cavalier.

Why this one?

1) It's simple - it has hi/lo beam switch, turn signals, tilt, and the ignition switch. No radio controls, no delay wiper switches, no extraneous stuff at all. This reduces the weight, and the number of gizmos that can go wrong.

2) They're plentiful - every wrecker has a bunch of 'em. Look for one that has nice, smooth bearings, without excess play.

3) They're break-away designed, with simple-to-fabricate mounts that maintain the frangible design.

4) The tilt mechanism (unlike most of the others I found) is situated almost at the steering wheel. Most others have the tilt mechanism much further away towards the firewall, meaning a lot more of the column's length has to move up & down - this can be a real problem in mounting in a Locost.

5) Every aftermarket wiring harness made in North America has a harness that plugs directly into these columns. I'm no wiring whiz, so "plug-'n-play" is a BIG plus for me!

6) The shaft inside the column is "Double-D" - the standard for all aftermarket shafts in North America - so buying the steering shaft to the rack, and the required universal joints & support bearings, was dirt simple...and cheap (my shaft is polished stainless - BLING!).

7) As the British say, they're "cheap as chips".

Here's a pic -

Attachment:
Steering column small.jpg
Steering column small.jpg [ 156.5 KiB | Viewed 3088 times ]

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PostPosted: October 1, 2016, 1:10 pm 
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Joined: February 9, 2016, 8:46 am
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I went with a fourth gen. Camaro tilt wheel. Same reasons as Zetec7. Plentiful, cheap, has all of the controls necessary (Ignition, turn signals, tilt that tilts at the steering wheel, wipers, etc.)

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PostPosted: October 1, 2016, 3:04 pm 
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Joined: January 31, 2012, 12:49 pm
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Location: Louisville KY
Dismantalus wrote:
I went with a fourth gen. Camaro tilt wheel. Same reasons as Zetec7. Plentiful, cheap, has all of the controls necessary (Ignition, turn signals, tilt that tilts at the steering wheel, wipers, etc.)


And you can buy plugs for the wiring for about nothing. Hell, parts and advice is pretty plentiful no matter what on that one.

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PostPosted: October 15, 2016, 11:01 pm 
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Joined: June 18, 2016, 12:39 am
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Bear in mind that any tire's effective diameter is effectively 2x the loaded radius. The industry guideline is 97% of the unloaded diameter.
So if you run a 205/50R15, for example, the calculated diameter is 23.07" and a lot of the advertised diameters are 23.1" so 97% of that is 22.4"
Once you know what diameter you want, divide it by 0.97 to see what you need.


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PostPosted: October 16, 2016, 3:21 am 
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Location: BC, Canada. eh?
That would seem to be precisely correct - my 205/50-15's are 22 1/2" tall!

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PostPosted: October 16, 2016, 9:28 am 
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Joined: June 18, 2016, 12:39 am
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Did you just try a vertical measurement from the ground to the top of the tire on the car?


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PostPosted: October 16, 2016, 9:44 am 
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Joined: May 27, 2006, 9:46 pm
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Location: BC, Canada. eh?
Yep - without the car weighted, the tires are 23" tall...so, there's about 1/2" compression. As you say, effectively the tires act as though they're 22 1/2" tall.

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