TheSamba.com :: View topic - I.R.S. or Swingaxle Manx Dune Buggy? Pros & Cons

Sat Jun 13, 2015 8:21 pm

First, both suspensions are IRS. Independent rear suspension is when each rear wheel can travel up and down without affecting the other. In reality, one rear suspension is called a swing axle and the other is called a diagonal arm suspension. It seems like everyone has succumbed to the "Follow the Herd" mentality of believing diagonal arm suspension is better. Here are some questions and thoughts:
If diagonal arm rides better, why did VW have to put a longer torsion bar in? Is it because the diagonal arm does not move in the same axis as the torsion arm and gives more resistance to movement.
I have yet to see a diagonal arm buggy that does not have a bent diagonal arm. Which makes it impossible to align correctly.
If you have put a swing arm torsion bar in your diagonal suspension, you have no suspension movement. Little red wagon ride!
Diagonal arm suspension is not stronger, ever hear of a swing axle axle wearing out or breaking.
A lots more parts to go bad in a diagonal suspension. Check your diagonal arms front bushing! Make sure your CV axle bolts are tight!
Ask any old VW mechanic that worked at the dealer, which one he prefers?
ON THE PLUS SIDE Diagonal arm suspension is better off road, but, it is a poor off road suspension.
ON THE NEGATIVE SIDE Swing arm is a little harder to work on, WAIT, no it's not.
In other words, I LOVE MY SWINGAXLE![/b]
The next time someone says IRS is better, ask them why!!!!!!!!
The typical answer will be: Oh, It just is.

Sat Jun 13, 2015 9:41 pm

It just is!!!!!

Sat Jun 13, 2015 9:54 pm

IRS will give you better handling and the longer torsion bars were for a "softer" ride in standard beetle.. You have to remember suspension in almost any street car has to have marshmallow ride to please lard butts becasue 95% of car buying public requires it because they do not understand or desire firmer "handling" ride....

Actually ride is determined by torsion bar diameter, spring rate and for standard beetle the spring rate was pretty much the same whether IRS or SA.. Torsion bar diameter and preload has large factor on how rear suspension responds... Did you know rear VW torsion bars comes in 3 different lengths and several different diameters (rates)...

IF you have ever done any performance driving you would throw rocks at a swing axle after driving a IRS car, I have had both a swing axle buggy (my present ride) and a buggy with IRS setup as autocross (actually raced both) .... If I had to do it all over again, a IRS/BJ car would be absolute first choice.... IRS rear suspension has better tire contact with pavement becasue camber of tire stay truer and increasing tire patch size for traction under cornering condition....

Obviously you have never read any books on suspension design and chassis setup or done any performance driving with IRS rear car or you would have completely different out look....And quite frankly I have never had an issues with rear alignment on either swing axle or IRS rear as I happen to under stand how the suspension works and how to adjust it and or correct any problems as you allude to as a "bent arm"...

IF you properly maintain the bearing setup in micro stub axle assembly and understand CV Joint lubrication and prepping (clocking), lack of longevity is not a problem....

One point that I will agree with you is both rear suspensions are independent... But we accept and use the term Swing Axle (SA) as a descriptive form for and axle arrangement as it is described in any good reference material on rear suspension and the term "IRS" is just common vernacular for to simply describe the more complex parallelogram geometry independent rear with dual CV Joint and a (generally) open axle rear suspension again as described in learned materials on steering and suspension...

Suggested reading may be "Chassis Engineering" by ADAMS published by HP Books...

http://www.amazon.com/Chassis-Engineering-Building-Performance-Handling/dp/1557880557

You whole comments pretty much strikes me as you are trolling for a argument.

Dale

Sat Jun 13, 2015 11:47 pm

Wow!

How many VW's have you owned? Have you driven them for thousands of miles continuously? Have you ever raced a VW, on road, off road? Have you ever put 140 horsepower through a VW swing axle, and a IRS? How many transaxles have you personally rebuilt? Have you driven a buggy at 90 + MPH to see which handles better? Do you align your own suspension, or take them to a shop?

I have seen as many swingers fail as I have IRS's.

Each have their attributes, and each have their detractions. But your statements are, well, not very well founded and miss-guide people about facts.

The human race did not leave the stone age for the bronze age because they ran out of rocks. And VW did not leave the Swing age for the IRS age because that ran out of Fulcrum Plates.

Sun Jun 14, 2015 12:04 am

My first VW had "IRS" rear, drove it for years and thats what I was use to. My second VW was SA rear, first time I punched it around a corner felt that outside tire want to tuck under and felt the rear come up scared the hell out of me.

I prefer IRS to the point my current buggy is getting converted to IRS from SA as soon as possible.

SA might have stronger axles but for mixed street and off road driving I think IRS is the way to go, VW must have changed for some reason?

Sun Jun 14, 2015 8:10 am

Quote: SA might have stronger axles but for mixed street and off road driving I think IRS is the way to go

If you upgarde the CV's, they are a lot stronger than SA axles. I have broken more spades/paddles than CV's.

Sun Jun 14, 2015 8:47 am

Swingaxle bugs aren't as rollover prone as say a Robin Reliant but the swingaxle bugs tendency to wheel tuck is very real and very nasty

I bet EMPI sold more of these than shifters

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Sun Jun 14, 2015 9:32 am

Do the compensators work?

I had my first wheel tuck the other day; this caused an extreme amount of pucker too!

Sun Jun 14, 2015 9:41 am

This is you Swing Axle buggy under extreme cornering ...

And yes buggy has performance tuned suspension...

Dale

Sun Jun 14, 2015 9:46 am

The compensators do work.

When I did not have 2 nickles to rub together in school, I would buy the flop stops for a SA for about $ 1.99 and that eliminated the tucking, but they also limited the wheel travel for off road use.

For the street, a SA can be made to handle very nicely, but it takes some of the off road ability away.

As a side note, I am in the process of fabbing a custom rear sway bar for my Manx to help it handle better for my up coming trip across the US. It sits so high, and the center of gravity is also high to the point it was hard to follow Bruce up the Canyon to Big Bear last year. Since my wife will be driving some this trip, it is a safety factor I am willing to add and compromise the off road ability for this trip. Most likely will get unbolted once back home so I can run the trails here.

Sun Jun 14, 2015 11:31 am

Dale M. wrote: You whole comments pretty much strikes me as you are trolling for a argument.

Exactly my thoughts.

Sun Jun 14, 2015 2:10 pm

I got the comments I thought I would get. I was trying to find out what the general consensus was concerning Swing axles. You are the guys who have people believing they should all have IRS. I originally stated a IRS is better for off-road and it looks like racing a road course too. I knew that, but, for regular street use, I feel there is nothing wrong with a swing axle. It was around forever and pretty much problem free. I was hoping there would be someone to defend the Swing axle. I have no problems with mine and when I take corners too fast (a sharp right hand turn, like in many neighborhoods) in my Buggy, the problem is only having the front tires slipping out a little. The staged photo of the Beetle in the add, is only to sell the stabilizers. I can't believe you haven't seen bent diagonal arms. As many know when the vehicle is raised on an IRS suspension the camber is supposed to go more positive, but, it's negative when raised and a bent diagonal is to blame. Look at all the IRS Buggies you can. The only way to address this is to buy new aftermarket arms, you can't find used ones that are not bent. This adds more to the cost of having or changing to IRS. For street use, is IRS that much better than a Swing axle? Plus, you cannot forget the Beetle was never designed as a performance vehicle, IRS or swing arm.

Sun Jun 14, 2015 2:46 pm

And if you are only pussyfootin around on the street swing axles are fine. Just don't ever have to make a sudden abrupt steering correction or odds are you will be showing the greasy side of your buggy.
You need to step back in time here, study a bit of automotive history. Swing axles and their reputation killed the Corvair....with some help from Ralph Nader. Why did so many manufacturers that formerly used them give up on them? Hint....their replacements weren't cheaper. Porsche moved on, Mercedes-Benz found a better way....
I defy you to please show us a CURRENT application.

Sun Jun 14, 2015 3:07 pm

MILO63 wrote: The staged photo of the Beetle in the add, is only to sell the stabilizers.

That picture had nothing to do with the ad, it was just one of several I found on line. Here are some others

VWs and Corvairs weren't the only cars to suffer from swingaxle tuck under

Sun Jun 14, 2015 6:05 pm

Its not always that the trailing arms that are bent, the housings can bend too. After I replaced the pan on my 69 beetle the rear tires had negative camber, wasnt there before the pan was replaced and I reused my old trailing arms.

Sun Jun 14, 2015 7:40 pm

Wife had a Spitfire and first time I drove it hard it did that... Scared me...

Dale

Sun Jun 14, 2015 7:52 pm

Changing it up just a bit, I wanted to ask about IRS to Swingaxle conversion. I know lots of people have converted swigaxle to IRS, but what would it take to convert an IRS to Swingaxle. I've got a project buggy in the back yard with a shortened pan, and a prospective buyer was asking if the 1974 IRS chassis can be swapped to swingaxle. Not sure what all would be needed.

I know the trailing arms would need to be removed, and a drum to drum replacement swingaxle would be needed. Do the torsions have to be replaced as well, or is this even possible.

Sun Jun 14, 2015 7:52 pm

I had a pair of trailing arms I took off ony to replace them with 3x3. I could not give them away. Why could I not give them away? Because people's don't fail like you portrayed. I'm not going to lie, your a complete jackass. Not for liking SA just for spending that much time to type up as much as you did. If you love your SA so much why don't you open the drain port and drink. Then you can have your dream, it's inside you. On a happy note, drive what you got and have fun and if your wheels tuck, it's gravity's fault.

Sun Jun 14, 2015 8:00 pm

And just to add a little context to the original post....

Milo is the guy asking $55k for his Manx on Ebay.

Nuff said.

Sun Jun 14, 2015 10:53 pm

Bent IRS trailing arm? Why just bend it when you can BREAK it?

Despite having had this happen, which was followed by the Night from Hell trying to get out of the forest from behind a locked gate at 11:00PM, I'm still happy with my decision to build the buggy on an IRS pan. The handling is just that much better. My buddy gave me a set of good used arms (which were not bent), and I modified a set of reinforcement gussets to make them stronger. Back on (and off) the road!

Lee