whats the benifits and down falls??

how easy is converting a 61 bug to irs??

i have been offered a good 1600 irs box out of a kombi and i am thinkig of changing but have never done this conversion and dont really know how easy it is to do and the gains from doing so ..

cheers............


steff..............................

Can you weld? Are you willing to take the body off your chassis? Just two things that have to be done...
PLus, the kombi box must be mounted on custom mounts - it's not a bolt-in

What is it you want to achieve with the conversion

welding is no issue ... body off?? really?? bollocks to that then.. its a no go if i have to go that far .... i would like to get rid of the wicked camber i have and everyone goes on about how good the irs is over swing... personaly i woudnt have a clue which is better


steff..................

k, got some words from ya... this is all from Jeff Hibbards book.

BIG quotation:

"

is Swing Axel or IRS better? - Most of you will be stuck with the rear suspension your car has. If you have that option open, such as when building a car from scratch, you may ask, "Which suspension is better?"

SWING AXLE PLUSES - The swing-axel suspension offers lower 'unsprug weight', which is the weight that "bounces" with the wheel. This lets the tires follow road surface more closely. This results in less inertia for the shock absorbers to overcome.

The swing-axel suspension also has fewer parts. As GM's Boss Kettering said, "Parts left out cause no problems and cost nothing." This is even more true in the dirt. Fewer parts mean fewer parts to break, a blessing when it’s a long walk home. There’s an economic consideration, too. The swing-axel suspension generally costs less because of the old rule of supply and demand. More are available.

SWING AXLE MINUSES – In the negative column, the sing-axle suffers from excessive camber change. To restrict positive camber at full rebound, special spring-plat stops are needed to limit rebound travel. Also, longer axles and wider flanges should be used to reduce this camber change for given amounts of wheel travel.

Other swing-axle disadvantages stem from the use of the axle to locate the suspension. If you plan to go racing with a swing-axle setup, the axels should be checked for cracks, shotpeened, and polished at the transaxle end, and their ‘fulcrum plates’ carefully matched. To keep the axle tubes from bending under high loads, axle tube stiffeners, or overtubes, should be used.

IRS PLUSES – If you could ask a suspension engineer, he’d tell you the IRS, or semi-trailing-arm rear suspension is better. The IRS can be modified for additional ground clearance and wheel travel without the extreme camber change of the swing-axle. With longer travel, lower rate torsion bars can be used. The lower-rate bars provide a less-harsh ride. All the big-money racers use IRS.

IRS MINUSES – The IRS suspension has its drawbacks. Because the system has more parts to wear out or fail, repair and maintenance are needed more frequently. Boss Kettering wouldn’t like that. And because offroaders are encouraged to use every inch of suspension travel possible, the stock axle-shaft joints are forced to operate at angles they weren’t designed for.

The fix is to replace the stock units with type-2 or expensive Porsche CV joints. Another way racers make the axle shafts work at higher angles is by using Spicer or late-model Datsun Z-car U-joints and splined axle shafts. For details on this hardware, see page 38.

Other IRS components are at a disadvantage in severe off-road use. The semi-trailing arm and ‘stub’ axles – short axles in the hub carriers – must be replaced or reinforced so they’ll withstand the side loads experienced off-road. Otherwise they will fail.”

Another quote:

“

(comment to a picture concerning swing axle camber):

Tires of this swing-axle off-road-car are in positive-camber (bottom of tyres going inwards) attitude. High-rate torsion bars, increased preload and big tyres have contributed to the camber problem. Off-road race cars with this setup are notoriously twitchy and take extra driving skill.”

Hope that helps… phew… what an essay..

u get IRS, and that kombi box in... and u will neva turn back. (from what i have heard from everyone... am yet ot meet someone who likes swinger over IRS)

U gotta weld in some 'pivot boxes' is that what their called? get a kombi box transmission mount, ever 2nd hand or from custom offroad or the like..., get a set of IRS rear trailing arms and rest of the jazz, then get the axles modified (IRS axles with CVs) so one end is kombi end, and other end is beetle...

Mind you though, alot of people still use swing axle and get away with it... just a little different to drive ( i would assume). but i know of alot of swinger offroad cars, see em everywhere. There is nothing wrong with leaving it the way it is...

Jeff hibbard shows they both have ups and downs... so really, ones better than the other in another way, and visa versa...

If u don't want to do all that extra kombi stuff, i have been suggested (before i got an IRS end), to get a late, single sideplate IRS box (i think it was) off a late IRS bug... Go for a 1300 box... and u get lower gearing than 1600 bug... then u won't need to worry about axles being kombi to bug... and i'm not too sure, but might just be a bolt in job (would it guys?) then having a new transmission mount...

I'm not too sure if u need another tranny mount... maybe, cause the IRS rear forks at the back seem flatter than the forks on a swinger

[ Edited on 22/8/2006 by bajachris88 ]

You don't need to take the body off. Mine had the conversion done by custom offroad many years ago now, and they did it with the body still on. You just have to weld the underside of the pivot box top plate because you can't get to the top. It is easier with the body off.

On a 61 you also have to clearance the shock towers (notch them) so the trailing arm doesn't hit on full compression travel. The rear chassis forks also need to be heated and squashes a little to clear the CV's.

The main problem is you need a jig to ensure the pivot box is in the correct location before welding. I have seen plenty done without jig's and it results in weird uneven wheel camber.

IRS conversions
http://www.customoffroad.com.au/vw/partFull.asp?partid=37

Bare heavy duty pivot boxes
http://www.customoffroad.com.au/vw/partFull.asp?partid=36

IRS gets more traction as far as I'm concerned. I had a test track on my parents 5 acres and drove the track before and after the conversion, and I think the IRS gets better traction. Just like a IRS commodore gets better traction than the beam axle models.

IRS also lets you go to kombi boxes, which require a kit to adapt to the vehicle.
http://www.customoffroad.com.au/vw/partFull.asp?partid=25

The kombi boxes are stronger and give lower gearing which compensates for the big tyres on offroaders. You also need to run modified axles and run either kombi CV's on the inner only, or modify the stub axles as well and run kombi CV's in and out board.

modified axles
http://www.customoffroad.com.au/vw/partFull.asp?partid=26

I modified my stub axles myself with the help of a friend with some useful machines.


and I used a sharpbuilt kombi gearbox strap kit (which I don't use know with the way I set-up the V6 mounts)



Chris, Jeff Hibbards book is very old and the information in it is outdated, especially the info on IRS vs swingaxle. I doubt you'll even be able to find a competitive swingaxle offroad race car today. IRS is the ducks nuts.

go the IRS. with the 1600 kombi box climbing will be much easier with 31inch tyres too. Wes is right about the jig too, an absolute must.

Very Interesting...

Wes,
Are those beetle gearbox mounts with a custom bracket to take the Kombi gearbox?
or are they standard Kombi gearbox mounts?

My Sons Girlfriend's Baja is a 69 chassis with IRS welded to it...
As You say, it has to be welded on correctly... not an easy job, and probably very difficult... to get it 100% correct..

Its something I would never attempt to do..
and I didn't know that its a Not an uncommon practice...

I aways though people just used an Auto Stick chassis..
but maybe they are getting a bit scarce now...

Lee

Steff,
I think you are in Gladstone and I am in Rocky, I have a jig to do the IRS Conversion which you are welcome to borrow. I made it some years ago to do the conversion on my son's Beach Buggy (Supasports).The car runs true. We managed to do it with the body on.
We used a Type 3 IRS Box,Diagonal Arms, Torsion Bars and Spring Plates initially (All a bolt up operation) but are now planning a Kombi conversion.Contact us if you like and we'll tell you what we done.
regards,

Glenn

thanks for the replys... more inclinded to do it knowing i dont need to body off.... bloody fantastic that theres a jig so close (yes i am in gladstone).. so is the kombi box the way to go or a different irs box??

cheers

steff.................

For a Baja? Kombi box is the stuff. Once you have it set up for a 1600 box, an 1800 or 2l box will just bolt in. For big wheels and tyres and factory strength, kombi boxes are the go offroad. I'm yet to break my 1800 box.

onya Gleen thats good news and nice offer for steff
and one day me
lol
bernie

Yeh the converson wansnt really that hard to do... Especially for me (thanks dad):P:P

We knocked it over in a weekend, with the body on (although it was a buggy)

But Steff, my suggestion is dont do, just come driving with us instead!!!!!!!!:thumb:thumb