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PostPosted: June 3, 2018, 2:06 pm 
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MangPong (and others reading this) IF you fully "engineer" the UCA and LCA designs, you will need to know the forces acting upon it. It varies with each build's design, intended driving location, driving style, desired safety factors and more. Some will vary more than others. This is deeper than I am capable of doing, or willing to find out. The alternative is to use tried and proven materials.

There was a discussion maybe 5-8 years ago here where the various strengths of shapes and sizes were tabulated. You may be able to find it with the search function. Or you can use on online calculator to get various comparative strengths of sizes and walls. The first one on the list when I googled it was https://www.roguefab.com/tube-calculator/. I cannot guess the input factors for your build but relative numbers are easily obtained for beam loading. It becomes more complicated when considering column loading and any tube deformations present (dents) that may occur in use.

That's the best I can do for you.

Now back to Rumble's regular scheduled programming.

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Visit my ongoing MGB Rustoration log: over HERE

Or my Wankel powered Locost log : over HERE

And don't forget my Cushman Truckster resto Locostusa.com/forums/viewtopic.php?f=36&t=17766


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PostPosted: June 3, 2018, 7:59 pm 
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rx7locost wrote:
MangPong (and others reading this) IF you fully "engineer" the UCA and LCA designs, you will need to know the forces acting upon it. It varies with each build's design, intended driving location, driving style, desired safety factors and more. Some will vary more than others. This is deeper than I am capable of doing, or willing to find out. The alternative is to use tried and proven materials.

There was a discussion maybe 5-8 years ago here where the various strengths of shapes and sizes were tabulated. You may be able to find it with the search function. Or you can use on online calculator to get various comparative strengths of sizes and walls. The first one on the list when I googled it was https://www.roguefab.com/tube-calculator/. I cannot guess the input factors for your build but relative numbers are easily obtained for beam loading. It becomes more complicated when considering column loading and any tube deformations present (dents) that may occur in use.

That's the best I can do for you.

Now back to Rumble's regular scheduled programming.


rx7locost,

I think you hit the nail on the head...It all depends! For example:
  • My LCAs are beefy 1.00" thick wall tube, because they will be taking far more bending force (from the cantilever) than the UCA.
  • If your coil-overs are attached close to the spindle on the LCA, you can go with a lighter LCA.
  • If your LCA & UCA pick-up points are further away from eachother, you can use lighter UCA & UCA.
  • If you have small diameter tires and light wheels, you can use lighter UCA & UCA.
  • My Tiger 700 should weigh only ~600lbs (800lbs with me in it), so my UCA & UCA can be lighter.

In general, the UCAs take less stress than the LCA.

Instead of performing in-depth Finite Element Analysis (FEA) on every part in our chassis, I think most of us on this forum are simply using our best judgement. With that in mind, its probably better to error on the side of overbuilding the chassis & suspension.


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PostPosted: June 3, 2018, 10:17 pm 
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Many thanks guys for your helpful comments - appreciate all help. Will keep at it.

Sorry for the hijack...

MangPong.


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PostPosted: June 4, 2018, 10:39 am 
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It seems this thread would imply that a bolt on lighter weight br@cket would be the ideal set up. That allows the bracket to give instead of the control arms. Or course then the question is how light? And I'd guess you'd need a supply of brackets on hand.

But it's usually just about as easy to make several when you are making instead of just one.

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PostPosted: June 4, 2018, 7:56 pm 
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The Steve Smith circle track books recommended .090" chassis tabs to mount the A-arms of 3500+ pound NASCAR cars.


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PostPosted: June 18, 2018, 8:48 pm 
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TRX wrote:
The Steve Smith circle track books recommended .090" chassis tabs to mount the A-arms of 3500+ pound NASCAR cars.


That sounds about right.

My Tiger 700 will be 800lbs with me in it.


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PostPosted: June 18, 2018, 10:29 pm 
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I finished my steering components on the front subframe.

Click here to -> View the video

I decided to upgrade the Raptor's handle bar steering to a Mustang II rack and pinion unit. The pivot points on the Mustang II rack are exactly the correct distance apart to meet the VSUSP suspension modeling tool recommends. The Mustang II rack is popular with hot rodders, so they are are easy to find and cheap. The new rack was only $75 including tax and shipping.

However, there are numerous modification needed to make the Mustang II rack work with the Raptor spindles.

The first modification to the Mustang II rack was to adapt the steering rods to work with the Raptor ball joints.
  • I started by cutting the threaded section off the Mustang rack's steering rods
  • The Raptor's steering handle bar setup has inboard rod ends and threaded adjusters that I could reuse. I cut the threaded portion off the Raptor's inboard rod end.
  • I replaced Mustang rack's end by welding the Raptor's threaded section on instead.
  • I cut the threaded adjuster tube length down to fit between the Rack and the Raptor ball joint. I was careful to reuse the left hand threaded section and cutoff the right hand threaded side. This is because its much easier to find a right hand tap, than a left hand tap. I then tapped the adjuster tube's internal M12-1.25 right threads.
  • The threaded portion of the Raptor ball joint is oriented at 90 degrees to the ball joint. Unfortunately, that angle would not allow enough articulation for the full travel of the suspension up/down. So I cut the threaded section off the rod end and welded it back on at the correct angle. The welding put a lot of heat into the ball joint, so I removed the rubber boot and welded it in several short bursts and allowing it to cool between. I then cleaned the ball, replaced the rubber boot and re-greased it.

There are several versions of the Mustang II rack, such as the simple manual rack, the power rack and the performance power rack. I chose the manual rack because its lighter and it takes more turns to go from lock to lock (4 turns). Normally I would go for the performance rack, but I knew all the Mustang II rack would over-drive the small Raptor spindles and cause the wheels to turn too far and hit the body. The automotive standard for turning angle is 30 degrees in each direction.

To limit the Mustang II rack's travel, I removed the rubber bellows on each end and found there was a solid flange inside the casting that I could use as a stop. I then trimmed a some steel stock to limit the steering angle to 30 degrees. I then welded the steel stok on each end of the rack's internal steering rod.

With steering limiters in place, the steering rack is about 2.5 turns lock to lock. That's about right for a sporty feel.


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PostPosted: June 19, 2018, 12:24 am 
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You are very fortunate your local laws allow you to weld critical steering components.

As a licensed auto mechanic and insurance inspector, we aren't allowed to do that here.

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"If you can't build it safe, don't build it."

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Perry's TBird Based 5.0L Super 7 L.S.O
Perry's S10 Super 7 The 3rd
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PostPosted: June 19, 2018, 1:57 pm 
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horchoha wrote:
You are very fortunate your local laws allow you to weld critical steering components.

As a licensed auto mechanic and insurance inspector, we aren't allowed to do that here.


"Fortunate" would not be my choice of words? Welding in that application would concern me to no end. Not that I am adverse to welding all steering components in principle, like the laws say. I can't say exactly why with any certainty. Maybe heating the (possible) plastic ball retainer, or the immediate transition from thread to weld making a localized stress point, or maybe because some tie rod ends are forged steel which the soft weld material eliminates. I ain't no papered ungineer. Just a shadetree muchanic. I hope I am wrong.

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“Any suspension will work if you don’t let it.” - Colin Chapman

Visit my ongoing MGB Rustoration log: over HERE

Or my Wankel powered Locost log : over HERE

And don't forget my Cushman Truckster resto Locostusa.com/forums/viewtopic.php?f=36&t=17766


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PostPosted: June 19, 2018, 10:15 pm 
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rx7locost wrote:
horchoha wrote:
You are very fortunate your local laws allow you to weld critical steering components.

As a licensed auto mechanic and insurance inspector, we aren't allowed to do that here.


"Fortunate" would not be my choice of words? Welding in that application would concern me to no end. Not that I am adverse to welding all steering components in principle, like the laws say. I can't say exactly why with any certainty. Maybe heating the (possible) plastic ball retainer, or the immediate transition from thread to weld making a localized stress point, or maybe because some tie rod ends are forged steel which the soft weld material eliminates. I ain't no papered ungineer. Just a shadetree muchanic. I hope I am wrong.

I appreciate your concern. :oops:

I took great care to minimize the amount of heat that I put into the part, and ensured that the parts are thoroughly welded. The ball joint retainer is metal (vs plastic).

Since the Tiger 700 will only weigh about 800lbs with me int it, I think it will be OK.

If not, I'll be the first to know...

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PostPosted: June 19, 2018, 11:20 pm 
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Location: ontario
Where I live ,my builds would not pass the licensing mechanical fitness inspection with welded steering components. Even if they did, my instinct would be not to weld any of these components. All such parts I have seen were forged; there must be a reason for this :)


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PostPosted: June 19, 2018, 11:59 pm 
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Ughhh, I'm STRONGLY reminded of Paddy Hopkirk's misfortune with the Twin-Mini!
He did survive, but not lightly as I recall.
I think some rethinking is likely in order here. :shock:

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PostPosted: June 20, 2018, 1:26 am 
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rumbles wrote:
Since the Tiger 700 will only weigh about 800lbs with me int it, I think it will be OK.


My concern is that when the welded critical steering component fails, is that I hope you survive, but that you don't take the life of the innocent person driving their vehicle near you or walking along the road.

Do me a favor, this will cost you nothing. Your build will have to be inspected. Contact the inspection agency now and ask them if they will pass welding steering components. This costs nothing, may save you from rebuilding, and may save someones life.

I'm not pissing on you, my main concern is safety. Like it or not, us builders like to over engineer our build to keep us and the public safe. Welding critical steering components is not allowable, thats not my opinion, it's illegal for a vehicle that drives on public highways.

This great site, and members, all look out for each other, all advice is to be taken in a positive manner.

At the end of the day, every builder wants to pull into their driveway, turn off the key, and wipe that sh1t eating grin off their face.

_________________
Perry

'If man built it, man can fix it'
"No one ever told me I couldn't do it."
"If you can't build it safe, don't build it."

Perry's Locost Super Che7enette Build
Perry's TBird Based 5.0L Super 7 L.S.O
Perry's S10 Super 7 The 3rd
Perry's 4th Build The Topolino 500 (Little Mouse) Altered
Perry's 5th Build the Super Slant 6 Super 7
Perry's Final Build the 1929 Mercedes Gazelle


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PostPosted: June 22, 2018, 9:44 pm 
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Location: Charlotte
horchoha wrote:
rumbles wrote:
Since the Tiger 700 will only weigh about 800lbs with me int it, I think it will be OK.


My concern is that when the welded critical steering component fails, is that I hope you survive, but that you don't take the life of the innocent person driving their vehicle near you or walking along the road.

Do me a favor, this will cost you nothing. Your build will have to be inspected. Contact the inspection agency now and ask them if they will pass welding steering components. This costs nothing, may save you from rebuilding, and may save someones life.

I'm not pissing on you, my main concern is safety. Like it or not, us builders like to over engineer our build to keep us and the public safe. Welding critical steering components is not allowable, thats not my opinion, it's illegal for a vehicle that drives on public highways.

This great site, and members, all look out for each other, all advice is to be taken in a positive manner.

At the end of the day, every builder wants to pull into their driveway, turn off the key, and wipe that sh1t eating grin off their face.

I really do appreciate your concern! I agree that welding on a forged part is not as strong as on mild steel. For example, I started to reuse the donor Raptor A-arms, but the ball joint angle was wrong for my application, so it bound up when the suspension compressed. I could have cut the forging and welded it in the correct angle, but I didn't think that would be safe because of the amount of force on the A-arm ball joints. So I started all over again and built 4 new A-arms...Yikes!

On the other hand, my steering components were designed for far more demanding forces that it will ever experience in my little Tiger 700. There are 2 welded areas in my steering rods:
  • The weld between the Mustang II steering rod and the Raptor steering rod. Both rods are mild steel, so a good weld is as strong as the metal around it.
  • The weld to correct the forged steering ball joint angle. If there is a weak point in the steering system, this is it. I think I have a solid weld with good penetration here.

Action: This coming week I will tear down my steering system and test the welded areas. I will apply 5x-10x more force than it will experience on the car. I'll let you know the results on this forum.

BTW, welded steering components are not illegal in the North Carolina nor any other state to my knowledge. That rule came from the British MOT system and spread to many of its previous colonies, including Canada.


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PostPosted: June 23, 2018, 8:29 am 
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rumbles wrote:
horchoha wrote:
My concern is that when the welded critical steering component fails, is that I hope you survive, but that you don't take the life of the innocent person driving their vehicle near you or walking along the road.

Do me a favor, this will cost you nothing. Your build will have to be inspected. Contact the inspection agency now and ask them if they will pass welding steering components. This costs nothing, may save you from rebuilding, and may save someones life.

I'm not pissing on you, my main concern is safety. Like it or not, us builders like to over engineer our build to keep us and the public safe. Welding critical steering components is not allowable, thats not my opinion, it's illegal for a vehicle that drives on public highways.

This great site, and members, all look out for each other, all advice is to be taken in a positive manner.

At the end of the day, every builder wants to pull into their driveway, turn off the key, and wipe that sh1t eating grin off their face.

I really do appreciate your concern! I agree that welding on a forged part is not as strong as on mild steel. For example, I started to reuse the donor Raptor A-arms, but the ball joint angle was wrong for my application, so it bound up when the suspension compressed. I could have cut the forging and welded it in the correct angle, but I didn't think that would be safe because of the amount of force on the A-arm ball joints. So I started all over again and built 4 new A-arms...Yikes!

On the other hand, my steering components were designed for far more demanding forces that it will ever experience in my little Tiger 700. There are 2 welded areas in my steering rods:
  • The weld between the Mustang II steering rod and the Raptor steering rod. Both rods are mild steel, so a good weld is as strong as the metal around it.
  • The weld to correct the forged steering ball joint angle. If there is a weak point in the steering system, this is it. I think I have a solid weld with good penetration here.

Action: This coming week I will tear down my steering system and test the welded areas. I will apply 5x-10x more force than it will experience on the car. I'll let you know the results on this forum.

BTW, welded steering components are not illegal in the North Carolina nor any other state to my knowledge. That rule came from the British MOT system and spread to many of its previous colonies, including Canada.


In 2 minutes I found the Federal law prohibiting welding on commercial trucks. 49 CFR 393.209.
Quote:
(d)Steering system. Universal joints and ball-and-socket joints shall not be worn, faulty or repaired by welding.
I didn't look any further at the state level or for passenger vehicles. There must be some technical reasoning behind the Feds doing that.

I am not concerned about meeting any strength test. However you did say that you tried to keep the heat out of the part when welding. My concern is that. over time, it may develop stress cracks and eventually fail catastrophically.

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Chuck.

“Any suspension will work if you don’t let it.” - Colin Chapman

Visit my ongoing MGB Rustoration log: over HERE

Or my Wankel powered Locost log : over HERE

And don't forget my Cushman Truckster resto Locostusa.com/forums/viewtopic.php?f=36&t=17766


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