Homemade rear sway bar.

For road racing, autocrossing, or just taking that curve in style. Oh yea, and stopping!
nbuscemi
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Joined: Sun Oct 18, 2015 5:27 pm

Homemade rear sway bar.

Post by nbuscemi »

Yes, I know off-the-shelf rear sway bars can be had (assuming you can find one in stock) but why buy when you can build!?

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The center section and first 90* on either side of the bar is a factory 22mm sway bar from who-knows-what. I used some 1.5" steel pipe and an assortment of heim joints to attach it to the rear trailing arms. The frame mounts are hand made (hence their less-than-attractiveness) mounted to rear torsion tubes.

I test drove vehicle, no clunking or rattling... just go-kart like handling. Definitely makes a huge difference when hard cornering.

-Nick-
Ol'fogasaurus
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Re: Homemade rear sway bar.

Post by Ol'fogasaurus »

It is going to be interesting to see if or how long it holds up. My concern is partly the heat you put in when welding plus how much material the join cover has inside it. I really hope it works for you though and it does look pretty nice.

Lee
Ol'fogasaurus
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Re: Homemade rear sway bar.

Post by Ol'fogasaurus »

Think of a sway bar as a kind of a long fairly straight spring. What I am not sure of is are they bent then heat treated of the other way around. Like coil springs they twist vs. a leaf spring which kind of unbends the arc.

In the old days (my days) heating spring (coil or leaf) was done to lower the vehicle. It worked for a while but the loss of the temper (depending on how much heat was put in and to where it was done) was put into the spring allowed the coils to get soft (prematurely age... on some makes of cars especially) over time and the car continued to drop.

This is why my comment was made. Not sure if it will affect what you did or not especially on the levered end where the join cover is. The thought is well meant!

Lee
nbuscemi
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Re: Homemade rear sway bar.

Post by nbuscemi »

The thicker portion and the ends where the links attach are mild steel. The actual say bar was slid into the the thicker portion with an interference fit and plug welded as well as few small beads to prevent separation. This is all purely experimental and will be replaced with a proper Type 1 sway bar if/when this one fails.

-Nick-
Ol'fogasaurus
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Re: Homemade rear sway bar.

Post by Ol'fogasaurus »

nbuscemi wrote: Sun Aug 15, 2021 7:27 pm The thicker portion and the ends where the links attach are mild steel. The actual say bar was slid into the the thicker portion with an interference fit and plug welded as well as few small beads to prevent separation. This is all purely experimental and will be replaced with a proper Type 1 sway bar if/when this one fails.

-Nick-
Sounds fun to me. Just take it easy until you are sure of it as if the join breaks and the ends of the cross-piece drags and catches on the pavement then who knows.

I'm doing the same type of thing myself but not anything what compares even slightly to a sway bar you are doing but making a new roll-around garage clothes hanger setup from old thin walled mockup leftovers. I'm just taking short sections of tube, putting a filler into the two pieces then plug welding the pieces together.

Lee
Last edited by Ol'fogasaurus on Mon Aug 16, 2021 1:53 pm, edited 1 time in total.
Ian Godfrey
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Re: Homemade rear sway bar.

Post by Ian Godfrey »

nice work, and a creative solution as it is hard to get bars bigger than 19mm. I'vee just but a 22mm on the rear of my Ghia so I am interest to hear that you think it works well. What size do you have on the front?
nbuscemi
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Re: Homemade rear sway bar.

Post by nbuscemi »

Ian Godfrey wrote: Sun Aug 15, 2021 11:19 pm nice work, and a creative solution as it is hard to get bars bigger than 19mm. I'vee just but a 22mm on the rear of my Ghia so I am interest to hear that you think it works well. What size do you have on the front?
The front is stock. I plan to replace the bushings with poly and fabricate some brackets to attach to the front torsion tube to stiffen it up a little. From what I understand about rear engine cars, keeping the front soft and stiffening the rear will help neutralize the gross under-steer these cars have. I figure if the car can't be strait line fast then I want it to handle well.

-Nick-
Ol'fogasaurus
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Re: Homemade rear sway bar.

Post by Ol'fogasaurus »

Nick, there are several ways to soften up the front end, adjusters, especially on the top tube would be my first thought.

Lee
nbuscemi
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Re: Homemade rear sway bar.

Post by nbuscemi »

I'm not really sure I want the front end to be any softer than it already is and I'm happy with the ride height sitting on drop spindles. I'd prefer to keep the front geometry stock-ish. I need to push the car hard through some corners and see how the rear sway responds before I make any more changes. I've done engine tuning for years... pretty new to suspension tuning, especially on a rear drive, rear engine car. My starting point is to copy what Porsche did on the early air cooled 911s.

-Nick-
Ol'fogasaurus
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Re: Homemade rear sway bar.

Post by Ol'fogasaurus »

I agree that to wait to see what you need first before you get into the fun stuff is the best idea. The other stuff I mentioned (the tease) is for the later adjustment if or when needed.

Lee
Ian Godfrey
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Re: Homemade rear sway bar.

Post by Ian Godfrey »

Nick when you are comparing early 911 and VW, remember the 911 has a rising camber rate as the body rolls so the front wheels stay squarer to the road. Our cars (beam front suspension) and don't gain camber and as the body rolls we loose camber in the front :(
so often the 911's have close to the same anti roll bars front and rear, say 22 at both ends where our cars seem to go better with maybe 19 in the front to go with the 22 in the back. It will be interesting to hear how your car handles.
Ol'fogasaurus
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Re: Homemade rear sway bar.

Post by Ol'fogasaurus »

Also if there is a rake to the vehicle that changes camber also. If so, sometimes shimming the beam is needed to be done.

Lee
nbuscemi
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Re: Homemade rear sway bar.

Post by nbuscemi »

Ol'fogasaurus wrote: Tue Aug 17, 2021 9:31 am Also if there is a rake to the vehicle that changes camber also. If so, sometimes shimming the beam is needed to be done.

Lee
Funny you mention that. I have (but not installed yet) a pair of caster shims for the front beam. I need to get the car on an alignment rack. So far all I've used is a tape measure (for toe) and a camber bubble indicator to set my alignment.

-Nick-
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FJCamper
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Re: Homemade rear sway bar.

Post by FJCamper »

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On our historic vintage racing 1970 Ghia we run 19mm front and 16mm rear "antiroll" sway bars. The 16mm bars used to be available available in the distant past. I have an old one. The Porsche solution to the Porsche 911 handling problems was heavy front bar, light rear bar. That said, the 911S came with 15mm front and rear anti-roll bars. As the cars go heavier, the bars got bigger. The 1976-77 Turbos got a factory front 18mm bar.

I'd love to have adjustable bars on our racer, but can't find any, so we compensate with tire pressures on our Hoosier Speedster (bias ply) racing tires.

The Type 1 356 and VW beam axle front suspension has almost no antidive, so to compensate, you should run bigger rear brakes than front, or at least equal. We run the widely-copied ATE-style cast iron calipers (40mm left and right pistons) and on standard rotors they work for us. Racy cross drilling is optional.

In a hard corner, the front beam axle rolls with the car body itself (making them lean) and induces understeer as the front tires lose contact. This comes to us straight from the 1930's Auto Union Porsche-designed P-Wagens. Want to see a P-Wagen front axle beam? Look at a VW axle beam.

Even with the great improvement of the 4-joint rear suspension, the rear tires again are subject to tilting with the body. The only defense against this on our Type 1 chassis is stiff front and rear antiroll bars to try and keep the car flat. The fly in the buttermilk is stiff front bars invite tire lift right off the pavement. Even stock Ghia's will lift a front tire with the factory sway bar. That's because the spring rates of the stock front torsion bars exceed the spring rates of the softer rear torsion bars.

We've proven the classic Type 1 VW suspension with fairly little modification can get out there and run with the "real" sports cars. We're number 13 in this qualifying session at Road Atlanta.

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Ol'fogasaurus
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Re: Homemade rear sway bar.

Post by Ol'fogasaurus »

Great post FJ. Like so many other things when dealing with things like vehicles "Catch 22" gets involved.

"According to Merriam-Webster, catch-22 is defined as " a problematic situation for which the only solution is denied by a circumstance inherent in the problem or by a rule ." :shock: :roll: :lol:

Lee
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