DIY - Narrowed IRS Stock Trailing Arms

[dd-ardvark]

DIY - Narrowing IRS Stock Trailing Arms

The easy way to narrow a stock arm, well have you wondering “Why didn’t I think of that”.

Narrow it at the Inside Edge of inner Pivot and not at the axle assembly. See attached picture / link. I clipped this out of another one of my drawings. http://rides.webshots.com/photo/2277745 ... 9491PWUDPb


I won’t tell you how to do it, if you can’t figure it out from the picture, No offence but you need to have someone else do this modification for you. This is a drawing of a tubular trailing arm; envision in your mind a stock arm that shows the cut section and the added section to be welded back on. That simple!

- The geometry per say is not being changed.

YES - It makes the arm a little longer.

YES - You have to clearance your trailing arm spring plate and shock snubber, dependant on your tire width and ride height.

YES - You’ll have to use a single torsion spring plate. Be it single or double, your torsion spring plate is a lift object, in this case the cars weight using the torsion bar. Remember, you’re doing this because of clearance issues.

So, when you bolt this on your car, your TRAILING arm spring plate, is now going to be on the inside edge of your TORSION arm spring plate. This distance well be filled with either a shim or washers.

David / dd-ardvark

[DORIGTT]

Who's the supplier on those tubular arms you have?

[dd-ardvark]

Mark Johnson with http://www.blindchickenracing.com/
(Mark posts on the offroad section here)

Mark made mine around 2004-5 and I believe John with http://www.aircooled.net/ use to carry these.

I don’t see these advertised on either site anymore, but just ask. I did read a little, a few years after Mark made mine that some people were having alignment / camber issues. I’m using inside adjustable pivots so this was of no concern to me.

My brother recently picked up a set of 3x3 at http://www.averysaircooled.com/offroad/ ... garms2.cfm he was told they custom make narrow ones additionally.

David / dd-ardvark

[EastCoastOffRoad]

Would you have to cut your axles too to make them shorter?

[dd-ardvark]

Yes you do…, but you’ll need new ones. It’s pretty straight forward and I’m sure it’s been covered. But just for you…,

Sway-A-Way makes a conversation axle for putting a VW bus 002 or 091 transmission into a bug. http://www.swayaway.com/Axles.php Part Nos. 2015 and 2415

The axles supplied in the kit are 15.625” long, bugs axles are 16.25”. The axles come in VW spline sections with 2.375” long splines or Porsche 930 at 3” long spline sections.
The saving grace, if your car has 930’s or type 2 CV’s, they unplug farther and articulate more before binding. With the 930’s you can shorten by at least 1.2” off each end of the axle and just regrove the end with a band saw.

Now you got an axle 2”+ shorter for $300.00 dollars…, or your can have a custom set made up for $825.00, your call.

David / dd-ardvark

[DORIGTT]

Hey David,

What is the handling like with the narrowed rear arms?

[DORIGTT]

Jiggle, jiggle, jiggle.

[Piledriver]

The TAs John used to sell get you only about an inch per side, and when I looked into it last year, blindchicken had cut up//repurposed the jigs to make something else, due to no demand. No sale, and especially not happening at ~$350 per inch of backspacing. (not including wheels/axles)

Regardless, to get serious tire underneath stock fenders requires similar work to the trailing arm and narrowing the torsion housing, plus tubbing the inner fender area.

IMHO, not really worth it on a car that has fenders that unbolt and can be had/made in any width and still look ~stock at 60 MPH.

On a Ghia and to a lesser extent a T3 narrowing can make sense, Ghias have double layer handmade (and welded on) outer fenders and a "perfect" classic shape... and T3s with big old fat fenders... can look funny. (although you can fit pretty decent meat under a ~stock T3 with the proper wheels, 7s are no problem) Plus, you can drop the rear torsion out of a T3 to do most of the mods by removing a few bolts, rather than having to do it all in place.

Here's a great page on the full meal deal, also effectively gives an idea on how to just narrow the arms, or make your own.
(Mike Lawless's Ghia)
http://home.comcast.net/~mlawless29/wkrswingtoirs.html

Handling should be ~no different if you did it properly.

[DORIGTT]

Blind Chicken Racing - the former supplier to Aircooled.net, is pretty close to where I live in the Portland area. I've taken the plunge and ordered a set from Mark and will pick them up this weekend.

Cross your fingers that I'll be able to tuck the wheels I've got like I want. I've got a Ghia which means I don't have a bolt-on fender option.

[Chip Birks]

Wide fenders on a bug are UGLY IMHO. Even a stock rear end on a bug can fit a lot of tire with the right offsets. My 215x65x15s have a lot of room to grow, if I want.

[Chris V]

The largest tire I've fit under the back of a stock fendered Beetle was a 235/60-15...Under an 1-1/4" wider fender - 255/40-17 on an 8.5" rim...with room to grow, if I want.

It's a pain in the neck fitting bumpers/lights to fiberglass fenders, but I'd rather not have trick axles/questionable arms. Shoot, I've replaced a couple munched IRS arms on our cars in recent years - it's nice to clean off another from the pile and have it bolt right up...and CCC has shipped me out a replacement fender fast.

[DORIGTT]

What killed the IRS arms?

[Chris V]

Other motorists