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Old March 7th, 2006, 12:25 PM   #1
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FONZY's Avatar
Join Date: Mar 2005
Location: Sanger, TX
Posts: 2,820

I wanted to lower the rear of my IRS beetle beyond the normal '2 notches' but one problem encountered with this is 'Ze Germans' engineered in a few degrees of camber in the rear suspension, so when you drastically lower it, the rear wheels lean in at the top very much like a swingaxle suspension. What this is basically boiled down to is a slight built in angle in the leading pivot for each trailing arm. To counteract this effect, I'm using a neat trick which entails swapping and flipping the trailing arms from side to side. At normal ride height the top of the rear wheels will then spread away from each other, but when lowered, will pull in to a vertical position. This is actually a pretty simple modification that could easilly be done in a weekend, with the body on or off.

First things first, a bit of teardown and clean up. Stripped the trans, axles, brake lines and whatnot.

Now off with the trailing arms... the inner pivot uses the same size allen head as the transmission filler plug.

...then the spring plate arms... after removing the spring retainer plate, you will want to be extremely wary of the spring plate... it is under a load and will release as soon as you bump it off it's stops. I used a couple love taps with a small sledge to persuade them out...

Since were swapping the trailing arms side to side, the lower shock mounts and bump stops will need to be cut off and reattached upside down and swapped from one trailing arm to the other, from stock...

You can even weld them back on the same place you removed them from...

Now with the bump stops, I opted to scavenge some off of an early swingaxle since I can shorten them up more than the stock IRS bracket, gaining a precious bit of extra travel in the lowered suspension before bottoming out.

A bit of trimming and careful alignment (it doesn't sit 'square' to the trailing arm) and I cut off all but an inch of the rubber stops, again for a bit more travel... still effective and cheap:)

In addition to the trailing arms, you have to swap the spring plates from side to side so the holes will line up again. Also made a notch in the top edge of the spring plates so they don't bottom out as early... Note that you don't want to go nuts removing material here since it will drastically weaken the spring plate. Also, make sure you cut the correct spring plate on the correct side...

Also had to notch out a small corner of the trailing arm bracket where it attaches to the spring plate to clear the 'stops'...

One more spot you can do a bit of clearancing is right above the lower shock tower mount. I shaved off and rewelded the factory flange where it will hit the underside of the stop.

Now time for some assembly... I went ahead and rebuilt the brakes / E-brake assemblies, new bearings, seals, bushings... For you guys who take the brakes apart and don't remember how it goes back together...

here ya go

a bit of sanding, primer and gloss black rustoleum...

Now on to reassembly...

Put on the rubber donut bushings (inner and outer) then fully seat the outer end of the torsion spring back into the spring retainer cup...

Then slide this assembly into the rear torsion tube. You will want to 'place' the inner teeth onto the correct notches at this point, dependent on how low you are going...

If you replaced the rubber donuts like me, you'll find they won't just pop back into place...

I used a couple of threaded clamps to pull everything together, and a couple screwdrivers to hold everything into alignment, then get the bolts started.

Tighten it all up. The spring retainer plate should cinch down all the way flush... no gaps.

...and a shot of my 'drop' settings. I left about 1/2" under the spring plate... now this doesn't look like much but after the tranny, motor, body and all the trimmings are back in the car, it will sink a good 3 inches.

Once you have the spring plates where you want them. slap the trailing arms back on and yer done!

Notice there is PLENTY of room for lowering this down to the ground, and it will have a dead vertical or very very close to vertical rear wheel.

...and reference shot of stock...

Hope this shed some light on how to lower the rear end and retain a nice vertical wheel.

And just like the man said... be sure to read, understand and follow the instructions and safety rules for your tools! and don't forget the most important safety item of all, safety glasses.

good luck!
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