Author Topic: Slow Car Fast  (Read 7825 times)

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Offline Rex Schimmer

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Re: Slow Car Fast
« Reply #30 on: January 27, 2022, 03:23:21 PM »
Mat,
Love your new video! Your method of frame fab really shows the advantages of using CAD to draw it up as it has allowed you to have all of the tube precut on a laser CNC cutter and  they all fit together! and perfectly!! Really like the locater notch. Very cool. I am glad that you are reconsidering the diagonal tube at the rear to intersect where the second roll bar meets the upper frame rail as provides a good load path and really strengthens the frame. I assume that you are planning to weld in some sort of spool through the rear rectangular frame rail where it bolts together to keep the tubes from crushing. I hope that you are not planning to use the upset style threaded inserts that you have used elsewhere as these are, in my mind, useless. If you have ever had one start to turn after it was installed you will agree with me.  You may want to also provide some horizontal diagonals on the rear part of the frame behind the rear wheels especially if you at some time decide to run a large vertical stabilizer, as it can generate pretty large forces if you get into some sort of side ways position at speed. On your square tube structure in the front to carry your water tank you may want to make the top tubes removable so that you can insert the water tank from the top.

Keep up the great work, learning great stuff all of the time from your vids.

Rex
Rex

Not much matters and the rest doesn't matter at all.

Offline Stan Back

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Re: Slow Car Fast
« Reply #31 on: January 27, 2022, 04:42:29 PM »
I took a quick look at the rules and I guess a Dash-15 suit may be all that is required.  If it was me (and it's not) I'd go for a Dash-20 any way. The faster you go and the slipperyer(sp?) you are, the farther you might travel before anyone can get to you in an emergency.  And, unlike a roadster, the longer it may take to get you out.  They're a little thicker, but in your driving position it might be an asset.  I've preferred a two-piece as you can function with just the bottom before and after a run.
Past (Only) Member of the San Berdoo Roadsters -- "California's Most-Exclusive Roadster Club" -- 19 Years of Bonneville and/or El Mirage Street Roadster Records

Offline Interested Observer

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Re: Slow Car Fast
« Reply #32 on: January 27, 2022, 08:39:24 PM »
Well, Rex beat me to suggesting the notion of having an anti-crush bushing or block for the bolts in the rear frame bolted joints.  But beyond that, I would be rather leery of that style connection in the first place--too much difficulty with alignment, tolerances, interface fitment, corrosion, and wear.  Some sort of flanged connection would seem to be simpler, more robust, and easier to live with.

Am waiting to see what you have in mind for the rear frame to control what, at this point, looks to be very limber in roll rotation.

With you in the frame, there appears to be little space for the pedal arrangement.

Front suspension sub-frame is, again, BOLTED(?) to the main frame?  Using thinwall tubular members?

Could you show an example of the CAD drawing of a tube element as would be needed for laser cutting?

Offline matmospheric

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Re: Slow Car Fast
« Reply #33 on: January 27, 2022, 10:17:11 PM »
Mat,
Love your new video! Your method of frame fab really shows the advantages of using CAD to draw it up as it has allowed you to have all of the tube precut on a laser CNC cutter and  they all fit together! and perfectly!! Really like the locater notch. Very cool. I am glad that you are reconsidering the diagonal tube at the rear to intersect where the second roll bar meets the upper frame rail as provides a good load path and really strengthens the frame. I assume that you are planning to weld in some sort of spool through the rear rectangular frame rail where it bolts together to keep the tubes from crushing. I hope that you are not planning to use the upset style threaded inserts that you have used elsewhere as these are, in my mind, useless. If you have ever had one start to turn after it was installed you will agree with me.  You may want to also provide some horizontal diagonals on the rear part of the frame behind the rear wheels especially if you at some time decide to run a large vertical stabilizer, as it can generate pretty large forces if you get into some sort of side ways position at speed. On your square tube structure in the front to carry your water tank you may want to make the top tubes removable so that you can insert the water tank from the top.

Keep up the great work, learning great stuff all of the time from your vids.

Rex

Glad you enjoyed the video and thanks for the feedback. I will be welding inserts into the rectangular tube and running bolts all the way through. definitely no rivet nuts there. I'm sure you're right with the sideways tail stiffness. I haven't put much thought into that part, it's just a quick sketch. I had planned on putting the water tank in from the bottom. the two top tubes are there to direct the load from the front suspension carrier directly into the safety structre side tubes. I have a bracket that I didn't show that does the same thing on the bottom but outside of the water tank area. It will stiffen the structure and add a lot more area for fasteners.

Well, Rex beat me to suggesting the notion of having an anti-crush bushing or block for the bolts in the rear frame bolted joints.  But beyond that, I would be rather leery of that style connection in the first place--too much difficulty with alignment, tolerances, interface fitment, corrosion, and wear.  Some sort of flanged connection would seem to be simpler, more robust, and easier to live with.

Am waiting to see what you have in mind for the rear frame to control what, at this point, looks to be very limber in roll rotation.

With you in the frame, there appears to be little space for the pedal arrangement.

Front suspension sub-frame is, again, BOLTED(?) to the main frame?  Using thinwall tubular members?

Could you show an example of the CAD drawing of a tube element as would be needed for laser cutting?


I think you convinced me to close off one side and add a flange perpendicular to the length of the car. I should be able to weld in a simple gusseted flange that will allow for another fastener on each corner, but also fully constrain the front to the rear on all three directions. I haven't packeged everything in the rear area, so I am also waiting to see what I do with rear stiffness :)
I have CAD modeled my pedal assembly. It's tight but looks like it fits. There is a small chance that the brake master cylinder protrudes into the water tank area slightly. in that case, I will modify the water tank. I really need to get a seat in and check actual fit. And yes, the front will be bolted, using several fasteners and reinforced plates. I'll have a better design to show in the future. I think it will be okay, but I will definitely do the calculations.

I'm not sure I understand your question about the tube element. Can you clarify?

Offline Interested Observer

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Re: Slow Car Fast
« Reply #34 on: January 28, 2022, 08:37:43 AM »
Quote
I'm not sure I understand your question about the tube element. Can you clarify?

I think it would be educational to have an example of what the laser-cut guys need to work from to do their thing.  I assume you sent them drawings of a series of the various individual parts which were needed.  Or, did they "dismantle" your complete frame drawing themselves?

Offline Skip Pipes

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Re: Slow Car Fast
« Reply #35 on: January 28, 2022, 03:50:57 PM »
Hi Matt,

I also love the video. Top shelf work, and in a home garage. Excellent. Hope to see your efforts at ElMo soon. Also, been a fan of the S600, great fun.

Skip Pipes
Skip's Garage
Builder of the SUNBEAM ALPINE Police Interceptor

Offline racergeo

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Re: Slow Car Fast
« Reply #36 on: January 28, 2022, 04:14:59 PM »
  I have 4 of the little "Don Garlits" top fuel front wheels and tires. Might help your packaging if they are legal. I think they are on a couple cars.

Offline Tman

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Re: Slow Car Fast
« Reply #37 on: February 16, 2022, 05:47:53 PM »
Matt, just stumbled upon your Youtube channel. Reading the comments on their is a hoot. Welcome.

Offline mabsmeier

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Re: Slow Car Fast
« Reply #38 on: February 17, 2022, 05:29:42 PM »
  I have 4 of the little "Don Garlits" top fuel front wheels and tires. Might help your packaging if they are legal. I think they are on a couple cars.
I have one on my sidecar. Was told at inspection that although they were originally good for 300mph now that they are all pretty darn old, 200mph is the limit.

Offline matmospheric

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Re: Slow Car Fast
« Reply #39 on: May 26, 2022, 02:59:34 PM »
It's been a while since I've updated this build here, but the car is getting lots of parts added and is starting to resemble a naked streamliner. The engine is installed and I finished up the steering. I'm hoping to have it in a condition to pass tech inspection at ElMo in June. It won't be running, but it'll be good to see what Tech says.

Couple of recent videos on the build:
https://youtu.be/cxFvodZKMjE
https://youtu.be/OFo0z-1HRzc


Offline fissionspeed

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Re: Slow Car Fast
« Reply #40 on: May 26, 2022, 03:31:54 PM »
Looking forward to seeing it in person!

Offline Rex Schimmer

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Re: Slow Car Fast
« Reply #41 on: May 27, 2022, 07:19:11 PM »
Mat,
Great progress! Looking at your weld on the front swing arm, please tell me that you ground the cad plating off before you welded things up. Looking at the welds it doesn't look like you did. Not good practice,big of chance of polluting the weld and reducing its strength.

I think your steering is very innovative and I like that you installed a tie rod between the wheels as it is not immediately obvious that you need one except it really makes a strong set up. Looking forward to seeing the car at the salt. Also like the way your steering bar and cross member really folds out of the way for getting in and out.

Rex
Rex

Not much matters and the rest doesn't matter at all.

Offline matmospheric

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Re: Slow Car Fast
« Reply #42 on: June 01, 2022, 01:37:45 PM »
Mat,
Great progress! Looking at your weld on the front swing arm, please tell me that you ground the cad plating off before you welded things up. Looking at the welds it doesn't look like you did. Not good practice,big of chance of polluting the weld and reducing its strength.

It's yellow zinc. I cleaned up the zinc in the welded area. What you're seeing is the zinc in the heat-affected zone outside of the weld. I should have cleaned it farther out from the weld because zinc is toxic to weld. Not great on my part, but the weld is solid.

Offline wickedwagens

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Re: Slow Car Fast
« Reply #43 on: August 15, 2022, 12:51:07 PM »
Glad I found the build on here too.  I just came across your videos last week and watched all of them on the liner.  Great build, and great videos.  I like the Slow Car Fast title as I'm running a Volkswagen Karmann Ghia...Slow car trying to go fast.

Mark
Ortiz Family Racing
1968 Volkswagen Karmann Ghia
G/CFALT  106.643 MPH  8/2016    G/CGALT  113.131 MPH  9/2016
G/CBGALT  169.462  MPH  8/2021    G/CBFALT  146.715  MPH  8/2017
G/CBGC  158.242  MPH  9/2017   H/CBGC  94.334 MPH  8/2018
H/CPRO  93.383 MPH  8/2018   H/CBFALT  101.282 MPH 9/2018
H/CBGALT  120.591 MPH 9/2018
Top Speed 170.726 MPH
36hp VW 100 mph club 9/2019 102.319 MPH

Offline Tman

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Re: Slow Car Fast
« Reply #44 on: August 31, 2022, 04:17:12 PM »
Congrats on the shakedown Matt! Car looked good under power. The "civilian" comment still slay me! Cheap entertainment!!!