540i Swapped Rat rod Build thread

[ThatRatRodProject]

Snap said:

Love the update and the plans you have!

Steel or alum for the suspension?

I see two points in your design that I would do differently with your suspension design but overall it looks good! Have you calculated Ackerman angle or modeled in the roll centers? Just curious. I know this isnt a racecar but im fascinated with your build

The control arms will be tube steel.

I have accounted for some of the angles. I will be running a very stiff spring rate. With low travel. With taller profile tires. So the tires absorb most of the bumps.

This is the look I'm going for.

I will be setting this car up for auto cross.

[Jdesign]

This is sweet!! I am glad you are still hammering away on it even though you hit so many bumps so early in the process. James' F20 powered model A will always be a sweet build, if done right, I see this heading the same direction.

[ThatRatRodProject]

Quick up date. Here is the car I picked up.

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[ThatRatRodProject]

Another update.

I started making the standalone engine management wiring harness out of the oem harness.

Im shaving all the unnecessary plugs and wires off the harness.

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[B C]

I wish you Godspeed

[Jdesign]

What management are you planning on using? Wiring always sucks.

[ThatRatRodProject]

Jdesign said:

What management are you planning on using? Wiring always sucks.

Stock Ecu and custom fuse box. Currently making one right now

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[ThatRatRodProject]

Great progress and success today with my custom wiring box. I have an official standalone engine management system for my M60b40.

After reading a lot of wire diagrams and taking a step out of my comfort zone. it all worked out in the end. This is the first time I've done any really serious wiring on a car.

--Ill let the pictures do the talking

Before

After

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[ThatRatRodProject]

Another update. I recently order a lot of supplies to get my project. This is going to be a picture update. And I designed up some clutch and brake pedals.

Not ordered yet but soon will be the tires

I am looking for a 3.73 or 4.11 medium case diff.

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[B C]

Awesome parts order! All top quality stuff!

[Jdesign]

Break that bank!! Glad to see the parts pile growing!!

[HipMF]

Lame updates. Get back to work!

[ThatRatRodProject]

So it’s been some time but this project is not dead. Updates will be coming. Re-designed front frame section sneak peak. 

[Jdesign]

Nice work! Solidworks?

I have so many questions.(Sorry) Is there a reason you are going with a cantilever set up? How did you calculate the the pivot arm length? Are there any shear concerns with the shock mounted on the top of the tube like that without any linear support? You obviously peaked my interest. I like what I see and I am very glad this isn't a dead thread.

[straight6pwr]

very cool!

Jdesign said:

 Is there a reason you are going with a cantilever set up?

seconded. it appears there is room for the coilover where you've placed that yellow connecting rod. are you using an undersized spring/shock and but increasing its effectiveness with the pivot arm?

what is the connecting rod coming forward from the pivot arm?

[m42b32]

straight6pwr said:

what is the connecting rod coming forward from the pivot arm?

Sway bar link maybe?

Looks great! I'm glad this project is still happening

[ThatRatRodProject]

m42b32 said:

Sway bar link maybe?

Looks great! I'm glad this project is still happening

Yes Sway Bar Link Set up will be coming off the cantilever toward the front of the frame. 

Linked Will Be the Sway Bar I'm Using. Haven't Modeled It in yet. 

https://www.summitracing.com/parts/rhc-19-0001

[ThatRatRodProject]

straight6pwr said:

very cool!

seconded. it appears there is room for the coilover where you've placed that yellow connecting rod. are you using an undersized spring/shock and but increasing its effectiveness with the pivot arm?

what is the connecting rod coming forward from the pivot arm?

There is a couple reasons why i have the coil-over mounted horizontally .

1. Keep it Clear of road Hazards like Dirt, rocks, Ect. 

2. I am using a under rated spring. So with the Cantilever allows me to achieve my desired spring rate with some sacrifice of overall suspension Travel.  Because i honestly don't know what the project will weigh in at.  I may have to re-fabricate the Cantilever Section. But This may be to stiff.

[GunMetalGrey]

Yeah this project was always intriguing, but has certainly caught more of my interest seeing things being modeled!

The shear area on that upper shock mount seems reasonable if you've got good penetration welds on both plates. 

I think I saw the knuckles in a picture on a previous page, but are those a standard purchased component?

I've always thought it would be cool to do a ground up build like this, so I really look forward to the continuation of this!

[ThatRatRodProject]

Jdesign said:

Nice work! Solidworks?

I have so many questions.(Sorry) Is there a reason you are going with a cantilever set up? How did you calculate the the pivot arm length? Are there any shear concerns with the shock mounted on the top of the tube like that without any linear support? You obviously peaked my interest. I like what I see and I am very glad this isn't a dead thread. 

Yes the Cad software i use is Solid-works. 

There is a couple reasons why I'm using a cantilever.

1. I have the coil-over mounted horizontally To Keep it Clear of road Hazards like Dirt, rocks, Ect. 

2. I am using a under rated spring. So with the Cantilever allows me to achieve my desired spring rate with some sacrifice of overall suspension Travel.  Because i honestly don't know what the project will weigh in at.  I may have to re-fabricate the Cantilever Section. But This may be to stiff. 

Attached is a image of a section View of the Cantilever. 

The stack up is From the top Down. 

Stripper Bolt (Shear Strength of  82,000 Psi (Roughly 28,000 Pounds or shear force))

Harden Washer 

Thrust Bearing 

Harden Washer 

Normal Ball Bearing 

Mounting piece (Gets Welded into the Cantilever) 

Normal Ball Bearing 

Harden Washer 

Thrust Bearing 

Harden Washer 

Mounting Blacking (will get mounted to the end of the tubing, (Tubing will likely be gusseted in the future)

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