IRS short axles

[Witty_username]

I narrowed my control arms 1 inch per side on my 74 ghia. I bought the type 3 automatic short side axles and they fit great but they are significantly smaller in diameter to the German originals that were in the car. I am putting a 2180 turbo motor in this thing and am concerned about the axles now. What are my options for a high horsepower 1" shorter axle? I have done my searches and can't find any good answers. Thank you so much.

[Ol'fogasaurus]

Witty, not sure about the strength of the strength of the joggle much less it's sharp angle in the seam of the two halves of the trailing arms.

Not sure about the axle length question but that is something different than what bothers me.

Lee

[Witty_username]

I've seen this done before and I feel like there is no way that this is any weaker than the factory arm. I internally gusseted it and then plated the whole outside. I'm not drag racing just a street car trying to do burnouts...

[Ol'fogasaurus]

Witty, I am not a graduate nor state licensed engineer. I am not a Technical designer (graduate or state licensed) either but I retired out of engineering as a company rated as a Tech Designer grade 6 but could not sign as an engineer (needed to be a grade 7 for that) but as a draftsman and dedicated checker of others work I had signature approval of "presentation" even over supervision (I could question parts of the design or if the presentation was wrong I could stop the release but again; not for Form, fit or function which was the engineer's job) had signed off.

What I think I am seeing are potential "stress risers" et al so I (unofficially of course) made a questioning post. It is mostly due to the right angles of the TIG welded stiffening flange(s) e.g., the welded butt joins that would normally be formed stiffening flanges and yes I did notice the stiffening pieces/brackets added. I look at is as a coin toss... you might be OK (for a while ?) or it may work forever but it is something I would/could not sign off on w/o an engineers or especially a PE's (a state licensed Engineer) endorsement.

I would also finish welding the ends of the stiffening flanges which is something that should be done to double up on the spot welded flanges on the trailing arms and the trans mounts even if you are only playing around not beating the "crap" out of it .

I pointed out what I thought I was seeing out only as an observation and not trying to be stuffy; it is your design and your build.

Lee

[Witty_username]

I welcome any observations! I try not to take anything "stuffy" on the interwebs. I appreciate the input. I am a welder/fabricator by trade and self-taught Solidworks "designer". I did put this design into a Solidworks load simulation and the arm folded up long before anything happened to my modified end. It does not compensate for stress cracks and I appreciate that advice.

[Ol'fogasaurus]

I welcome any observations! I try not to take anything "stuffy" on the interwebs. I appreciate the input. I am a welder/fabricator by trade and self-taught Solidworks "designer". I did put this design into a Solidworks load simulation and the arm folded up long before anything happened to my modified end. It does not compensate for stress cracks and I appreciate that advice.

Stress cracks were something we had to be very careful with in aircraft design. If a "Solidworks" analysis says it is OK then I would be more comfortable with it. CAD/CAM 3D was just finally being used (3D had been around for a long time but the discussion between CAD (engineering) and CAM (tooling programing) was finally finished and working. The updated version I was helping with was C++ with Boolean logic input version; in other words "Object oriented engineering". That was over 20 years ago.

Lee

[Bruce2]

Getting back to your original question.....

I bought the type 3 automatic short side axles and they fit great but they are significantly smaller in diameter to the German originals that were in the car.

A Type 3 automatic left axle is exactly the same diameter as the Type 1 axles your car was built with, so I don't understand why you think they are different?? The only difference between them is that the Type 3 axle is 26mm shorter.

I've had the same two left axles in my car for 28 years now. They are essentially indestructible in a street car with radial tires. If you are using stock CV joints, they are the weak point, not the axles.
What tires are you using?

[Bruce2]

Did you test fit your rotors before you welded them up?

TA_LI.jpg

If not, I predict they will interfere where the X is.

[Witty_username]

I did check that. It's close but they do clear! Picture does not show it well but that area is behind the original "face" of the arm! Good looking out though. I always tack and test fit because I hate doing stuff twice because I was rushing.

[Witty_username]

Bruce2 the diameter of the axle itself not the joint. The German axles that were in the car had axles that were 26mm diameter. The axles I bought for the type 3 were only 20mm. I returned the lefts and ordered sway away chromoly axles and that poses a whole new "issue" that I just posted about. I am running a Radial tire too by the way. I am also building a 2180 injected turbo motor and I wanted to have good axles fully understanding that their are many weak links in the chain but trying to alleviate some of them.

[Steve Arndt]

Sway A Way makes 1" shorter axles too. I've had them in my car since 1999.

[John S.]

I’ve never seen a listing for 1” shorter sway a way axles. Would be cool to get a part number. I know people also buy a sway a way or empi axle and just cut it to length, clean the splines and cut a new groove. They have plenty of extra spline length.
And I guess the OP had aftermarket empi replacement type 3 axles.

[Steve Arndt]

Bus Into Bug 15 5/8" Sway A Way or Empi axles.
https://www2.cip1.com/ProductDetails.as ... D16%2D2202

[Bruce2]

The German axles that were in the car had axles that were 26mm diameter. The axles I bought for the type 3 were only 20mm. I returned the lefts

I had the opportunity to measure some stock axles. Other than the two automatic axles in my car, I have a spare. I also measured a couple of 4 speed axles. All of them were 24.25mm in diameter. All are genuine VW.
It sounds like you found someone who sells a 1" shorter aftermarket axle, and it is only 20mm.