How to mount pedal slider?

What's the go to method for mounting the pedal slider to the chassis? The way it's designed it looks like you are supposed to use flat head bolts mounted top down through the chassis with a locking nut under the car? Just not sure i like the idea of having a nut and exposed threads under the chassis. Thinking of maybe using a binding barrel on the top side. Also are people swapping the wing nuts for nylocs since there's not enough clearance to spin the wing nut with the pedals mounted?


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Joel K

Supporter
Chris,

Here are a couple pics I have of the slider install. Looks like these builders used flat head screws with nuts underneath. I had that slider, but decided to go in another direction and sold it.

Counterboring the hole flat for a nut and washer makes a lot of sense so you don’t have the nut below the chassis.

Also I was planning on using either thumb nuts, trim the wings a little, or use hex lock-nuts.

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Thanks for the pics Joel! I'm still on the fence about using the slider, just trying to figure everything out in my head before making a final decision.
 
Here's what I made for my Miura project for pedal adjustment.

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It's simply a 1/4" plate of 6052 aluminum with a series of holes drilled into it. The pedals are mounted to the plate with screws counter sunk from the bottom side of plate. I then used button head screws to fasten the plate to the chassis with fender washers. That way it's just the rounded screw head and washer exposed on the bottom side of the chassis so nothing should catch on it. The only downside of using this method is that it's a two person job to move the pedals, but how often will the pedals be moved anyway? I'm guessing that pedal adjustment will mainly occur on change of car ownership unless you plan to split driving time with someone of a very different stature.
 

Ian Anderson

Lifetime Supporter
Why not go n some seat runners so they are easily adjustable

Or even an electronic seat adjustment so you can motor the pedals back and forth?

ian
 

Neil

Supporter
One thing to make sure of is to have either pedals or seat (or both) solidly located. Pushing on a brake pedal only to have the whole assembly slide forward will not have a happy outcome. I was a witness to an accident where the pilot of a light plane took off and when he pulled it up into a climb, his seat track was not locked so it slid backwards so far that his feet didn't reach the pedals. The plane stalled and crashed. Fortunately he had not gained much altitude by then and he survived.:mad:
 

Howard Jones

Supporter
So I hesitated to say this because I can see the utility of having either adjustable peddles, seat, or both especially if more than one person is going to drive the car. Maybe the wife will be a co-driver on road trips etc.

Having said that..... I tried to do it the same way that is posted in #4. It looks like a great idea and it is except that it all will flex quite a bit when you brake hard and somewhat when you use the clutch. I started with 1/8 6061 T6 and it was terrible so I tried 1/4 inch and it was still bad. I don't think anything less than .25 4140 chrome molly steel would work and I wouldn't be surprised if it didn't

What happens is you have two force multipliers at work. First, the brake peddle ratio is 6 or 7 to 1 but the length of the brake peddle as seen by the peddle mount is at least 8 or 8 1/2 inches long from the ball of my size 7 foot to the center of the peddle pivot point. The longer your feet the worse it gets! So you are seeing at least 800 pounds of force trying to bend the plate that the peddle assembly is bolted to when you press on the brake peddle with 100 pounds of leg pressure, and that is a moderate amount of leg pressure. After all, if you can do a squat with one leg and you weigh 200 pounds then you begin to get a feel for the forces involved.

But there is also the hidden leverage of the mounting location of the peddle FRAME bolts in relation to the PLATE mounting bolts. My design had them about two inches apart front to rear. This effectively ADDS to the peddle ratio as far as the leverage the PLATE mounting bolts are seeing. SO something like 10 to one!...................or more.............BIG feet.................a lot ......lot ....more.....

It's all a tangential math thing but it's real and it applies a lot of force to the plate that you have the peddle mounted to. I tried to figure out the math and came up with quite a bit more than 1200-1500 pounds of force being applied to the flat plate when I really stopped the car hard.

So nobody drives my car but me. I gave up and bolted the peddle frame right to the floor with four grade 8, 3/8 bolts. Ya, the seat is bolted down too. That arrangement is stiff as hell. The other wasn't and really bothered me when braking hard.

The slider idea would be a non-starter in a car that will get driven hard and NFinW in a track car. So that is my free observation and no-cost opinion. AND, If I'm being honest I don't like the idea of a MOVABLE BRAKE peddle MOUNT at all. It just adds a point of failure at the MOST critical point in the most critical system................brakes.

Please don't hate me adjustable brake peddle guys.........

Note: I changed to a Tilton peddle box since the pictures above but that doesn't change the point I'm making.
 

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I mounted my adjustable pedals using 3/8 flatheads with a 6x12 3/16 stainless steel plate under the chassis. I drilled lightening holes in the stainless plate. Your concern about the nuts hanging off is very valid as the bolt threads have bottomed out at times. At first I was concerned but then realized this most likely kept the seat lowering tubs from getting damaged. When the time comes I have extra bolts.
 
Appreciate the responses... Howard, great info, something that i wasn't really even considering is how much force is applied to the pedals during braking, etc. Really puts things into perspective about how critical the mounting is. Back to the drawing board!
 

Howard Jones

Supporter
I used my original design which I ultimately abandoned to locate the perfect spot for the peddle box. Then I transferred the mount points to the floor of the foot box and bolted the peddle box down. So I guess it was of use in the end. I kinda wish it had worked but at least in the end, it was a good learning exercise.

If there was a need to use something similar like if the wife needed to drive the car from time to time then I could be done I suspect but paying careful attention to redundancy and strength of the mounting systems would be critical. On second thought moving the seat might be a better idea because the belt mount points remain stationary with different drivers as only the seat moves. From a point of failure perspective that seems like a less risky way to go.
 
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