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Tue Sep 02, 2008 3:21 pm

What do I have to do to shorten the axle tubes on my stock 1970 IRS axle? I am talking about the short stub that sticks out from the spring plate and gets in the way of larger tires. I figure that I will have to buy shorter axles but are there any aftermaket ones that I should avoid? Any problem with different spline count? Thanks , Brent

Tue Sep 02, 2008 3:29 pm

It's not the axles, but the spring plates and torsion bars, which you kind of hinted at. IRS Bugs have the longer torsion bars, and the spring plates have the extensions to accomodate them. They get in the way of larger tires (generally anything over and sometimes including 31"), just like you said.

You can switch to the short torsion bars and either cut and redrill a set of swing axle spring plates to fit your trailing arms (I'm not a fan of this idea. Anyone done it?) or buy a set of aftermarket spring plates that are made to do this type of conversion. Just make sure the bolt patterns match up. I think Sway A Way makes IRS / Short Bar type spring plates. Those are the ones I would get. The ones to avoid would be any of the Chinese made knock-offs. Sway A Way makes quality products - you shouldn't have any problems with their stuff (including the torsion bars).

Lee

Tue Sep 02, 2008 3:31 pm

This might help:

http://www.swayaway.com/SpringPlates.php#

Lee

Tue Sep 02, 2008 4:22 pm

This book tells all about the conversion, along with a lot of other valuable info reguarding suspensions, brakes, roll cages, etc.

http://www.cbperformance.com/catalog.asp?ProductID=6

Tue Sep 02, 2008 4:59 pm

Hi tinnocker,

It also may worthy of a discussion on how big of a diameter you are actually talking about. As I originally researched front and rear tire sizes for my dune buggy build, I remember input relating to the fact that if you go too big in the rear, the tire size can significantly hinder the performance of the engine. I am personally running 275 60 R 15s on 15" x 8" rims (approx 28" diameter), and I am very happy with the result. I also have the longer torsion bars, and there is not rubbing or interference.

Others may have more technical input on the relationship between the rear tire size for optimum performance.

Tue Sep 02, 2008 5:22 pm

http://www.thesamba.com/vw/forum/viewtopic.php?t=316046 A picture of my short-bar IRS has been posted here. Its easy to do.

Tue Sep 02, 2008 7:36 pm

My mistake about the longer axles. I knew better, knew it wasn't the axles. I was talking about the torsion bar tubes. I used the larger tire reference just to let you know what I was talking about. I am building this buggy for the street and will not be running tires that may rub. I just thought the flat plate looks better than the one with the tube sticking through it. I am not at that point in my build yet and I may just run what I have. Thanks.

Tue Sep 02, 2008 7:43 pm

The flat covers do look better, plus you can run some CB Performance racing spring plate covers.

http://www.cbperformance.com/catalog.asp?ProductID=461

I have them on my buggy.

Wed Sep 03, 2008 8:16 am

One thing about the long bars is they tend to be more supple (lower spring rate) than shorter bars of the same diameter. If you don't mind the slightly stiffer ride, the short bars will be fine for the street.

Lee

Mon Sep 15, 2008 4:15 pm

Can anyone give me a picture of a ruler held up to a irs spring plate so i can get the dimensions for my conversion?

Tue Sep 16, 2008 2:57 pm

Use an IRS springplate, cut a template, mark your swingaxle springplate and start cutting. You need to match the IRS part (slotted holes and all) so that your rear alignment can be brought into spec.

Tue Sep 16, 2008 3:25 pm

I just found your PM, I'll try to post a photo tonight.