IRS setup for newbies...

[Merlin]

's up?

We've nearly completed my bug (chassis atleast)...

I started off with a Euro '67 (s/a) - stock, with 195/40/15s on EMPI 8s, '67 discs in front, and Rabbit Mk 1 discs on the rear.

I now have an IRS rear-end (double-springplates from a '68 Auto), urethane bearing replacements in the beam, urethane gearbox/tranny mounts, a urethane midmount, Bugpack Kafer Cup Bar, braided brake hoses, upgraded tranny, upgraded engine, and CB Performance 3/4 In. sway bars front and back (what was available).

We've built this car in a part of the world where this is definately not the norm', and as such I can't really jump into another car to see what they drive like.

Obviously this is going to be a rather different beast to drive...

What can I expect, and how do I go about setting up the sway bars?

I don't mind a little oversteer (I lie, I like it!), but this is a Daily Driver, and it needs to drive safely...

I know the tyres are too low profile - they're being changed out as soon as cash permits.

Any recommendations?

I'd like to make work what I have as we really struggle to get parts here, and quite frankly, the cash just isn't available to fix what doesn't need to be fixed.





Thanks, Nic

[perrib]

FJC Camper would be the person to ask. He moderates the Ghia forum and is an avid road racer. He has years of experience and knows what works and does not work.

[FJCamper]

Hi Merlin,

Good photos.

The front sway bar you have appears to be a 19mm, which is fine. Even nonadjustable. You may, say again, may, want to add a 19mm rear bar but that comes after you have the car on the road and are sorting out the handling.

The "may" applies to this. A rear bar makes the car handle better at low to medium speeds, but becomes dangerous at racing speeds. We run no rear bar on the fast road courses.

19mm front and rear nonadjustable bars mean you must adjust your handling with tires and tire pressures.

With the ball joint front end, adjust to get as much front negative camber as possible, which means you might get one degree or so out of it without special offset adjusters. The IRS rear takes advantage of front negative camber.

Do not use dune buggy or extra stiff rear torsion bars. Use stock bars.

You have the kafer bar bracing in the rear. Good. Excellent bracing. Be advised the urethane front transmission mount you have will flex if you have enough power. Flexing means jumping out of gear, especially on hard accelleration. We have been forced to run solid steel front trans mounts, and they fixed that problem ... but they're loud. You may not want that in a street car.

If you are tempted to lower the car, go no lower than 2" from stock, and make sure your rear axles are straight and level after lowering.

Nice looking chassis. Have fun and zap some ricegrinders.

FJC

[Merlin]

Thanks guys.

At the moment there is a strong 1776 going into the car, running twin Kadrons, a lightened flywheel, a complicated electronic ignition comprising Rabbit, Kombi 1.9, and an MSD 5 system, and a Serpentine belt.

The Serpentine will probably get pulled due only to manufacturing issues with it.

I forgot to mention that my chassis builder has fitted 22mm Type 3 torsion bars at the back. What is the issue with this, with regards to your comment above?

I'm far from an expert on all of this, so please don't get the impression I'm asking pointless Qs - I really am curious.

Is an adjustable front sway bar something I should aim to save for?

I'm not a racer - probably only due to finances (this car has taken a pounding on my savings) - but I do readily admit that I drive my bug like an absolute Hooligan. I'm primarily a split bus guy, and my bug is my toy.

At the moment I'm driving a relative's mild 1600 '66 bug with a slight drop, and camber compensator.

I'll pull the rear sway bar and see how things go once the bug is running - hopefully next week. Learn something new every day.

I also want to get rid of my EMPI 8s, due to rubbish offset - my rear wheels stick out a good inch or so past the fenders. At the moment they have 195s on with a ridiculous 40 profile. What would you recommend I fit to the bug? ...and pressures?

I'll have the local tyre shop set as much negative camber as possible up front. Thanks. Excuse the daft question, but what are offset adjusters?

My beam is running sway-a-way style adjusters, top and bottom. No drop spindles yet - cost. They've been welded in at an angle to only give downwards adjustability, and at the moment are set to their lowest.

I'll measure the drop and report back. The car is not at my place atm.

At the moment I have Prothane urethane tranny mounts fitted, and if they break, a spare set of CB Performance Rhino tranny mounts. Do you recommend urethane at the rear, and solid up front?

The noise doesn't phase me in the least. I have the use of other cars for transport. I have a seriously noisey exhaust anyways.

I have urethane shift and steering couplers too, which I'm told will also make it a bit louder inside. I've also pulled all of the engine bay tarboard out, in lieu of insulation inside, up the dogbox.

I may need to fit insulation in the engine bay again if it's really loud. I'll wait and see.

I plan on surprising more than a few people at the traffic lights.

...but getting sideways is more fun.

Cheers, Nic

[FJCamper]

Remember, sway bars work in an "X" pattern, throwing weight to the opposite wheel.

Hi Nic,

Offset adjusters look just like your standard ball joint camber adjusters but the hole for the ball joint attachment is offset slightly more than the standard. You can get more negative camber out of it.

Good thing is, these adjusters are cheap.

Changing the front end to negative camber makes handlers out of them -- it helps swing axles and transforms IRS's. Get 1.5 degrees negative if you can.

Stiff rear torsion bars ( and you have them) promote oversteer. I'd try them with no rear bar at all. You're going to have to lower the rear anyway to match the front, and the lowering will help keep the rear end from wanting to pass the front end.

Just keep the front and rear ride heights level with a driver and full tank of gas. Keep the battery behind the passenger seat meaning opposite the driver. Weight distribution.

A solid front trans mount is the only way to go for serious performance. You'll have much better shift lever action and feel. Rear trans mounts can be urethane, especially with your kafer bar.

The urethane front trans mounts flex badly under power, and the engine you're describing will begin to flex them. I am a big Kadron advocate, by the way.

With the stiff rear torsion bars and no rear bar, you might benefit from an adjustable front bar. Whiteline makes a good one, but it is not cheap. I'd drive the car for awhile before changing front bars.

Adjustable bars are for race track use, where you adjust for the track, hard for shorter, tight-cornered tracks, and softer for fast, high-speed tracks.

Yes, the EMPI 8-spokes have a bad offset. We use EMPI's but also steel 5.5-inchers with the stock offset, just the generic chrome types. since you have a Bug, with some fender room, get as wide a tire as will fit, but try and get round-shouldred tires.

FJC

[karol]

FJCamper

How much negative camber could you get with
a)stock eccentris adjusters
b)offset adjusters
How much is to much for track racing and fast street driving?

btw. Your posts are excellent info about usually overlooked things by vw people. thanks.

[FJCamper]

Hi Karol,

Stock ball joint camber adjusters are actually intended to provide zero camber for the stock alignment. You can twist them around to about a degree negative.

Actually, any negative is good. We run one and a half degree negative on our fast (130mph+) 1970 road racing Ghia, using offset adjusters. We do want some understeer up front!

Too much negative ("too much" -- being relative to how sticky your tires are and how your rear end is set up to make the front end work harder) and you will go from predictable cornering and sticking to sudden oversteer.

For street use, begin with one degree of negative. For track use, one and a half to two degrees. Some guys can get away with more, but we found 1.5- works for us. We use Avon racing radials, hard compound.

FJC

[Merlin]

Remember, sway bars work in an "X" pattern, throwing weight to the opposite wheel.

Hi Nic,

Offset adjusters look just like your standard ball joint camber adjusters but the hole for the ball joint attachment is offset slightly more than the standard. You can get more negative camber out of it.

Good thing is, these adjusters are cheap.

Changing the front end to negative camber makes handlers out of them -- it helps swing axles and transforms IRS's. Get 1.5 degrees negative if you can.

Stiff rear torsion bars ( and you have them) promote oversteer. I'd try them with no rear bar at all. You're going to have to lower the rear anyway to match the front, and the lowering will help keep the rear end from wanting to pass the front end.

Just keep the front and rear ride heights level with a driver and full tank of gas. Keep the battery behind the passenger seat meaning opposite the driver. Weight distribution.

A solid front trans mount is the only way to go for serious performance. You'll have much better shift lever action and feel. Rear trans mounts can be urethane, especially with your kafer bar.

The urethane front trans mounts flex badly under power, and the engine you're describing will begin to flex them. I am a big Kadron advocate, by the way.

With the stiff rear torsion bars and no rear bar, you might benefit from an adjustable front bar. Whiteline makes a good one, but it is not cheap. I'd drive the car for awhile before changing front bars.

Adjustable bars are for race track use, where you adjust for the track, hard for shorter, tight-cornered tracks, and softer for fast, high-speed tracks.

Yes, the EMPI 8-spokes have a bad offset. We use EMPI's but also steel 5.5-inchers with the stock offset, just the generic chrome types. since you have a Bug, with some fender room, get as wide a tire as will fit, but try and get round-shouldred tires.

FJC

Hi FJC,

Thanks. Your writing is very clear and helpful, and much appreciated.

I will try to source some stock torsion bars. My country never got IRS, so we're already dealing with a fairly unknown element here...

The front height will be adjusted and checked this weekend. The rear has been dropped 1 spline.

The battery is in it's stock location, on the right. This was thankfully a job we didn't have to do, being as how my cars is a LHD.

RHD cars (like we have here), kept the battery on the right.

I have a friend here who is pretty good with engineering, etc. I'll see if he can help me out with a solid front tranny mount, and I'll make a plan to source the offset adjusters.

The Whiteline bar will definately have to wait though.

I bought my car with the EMPI 8s. They're not my favourite rim of choice though.

99% of the cars here are 5-lug, so finding alternative rims is a bit of a problem. I am always on the lookout though.

I'm glad to see someone likes Kadrons. They have a bad rap. I bought these many years ago and they've just sat around waiting for an engine.

A good friend of mine runs Dellortos, and that is definately something I'd like to get...the sound is insane.

Cheers, Nic

[FJCamper]

Hi Merlin,

Type 3 rear torsions with no rear sway bar might work. The added stiffness will act like something like a sway bar.

Kadrons (Kadron actually being the name of the company that sells them) are really just redesigned Solexes, very similiar to the type Porsche used on the Supers back in the day.

They come with 28mm venturis, which is just right for all-purpose use, and I had 31mm and 34mm vents for ours. We ran the 2007 Carrera Panamericana in Mexico on ours, in a swing-axle 1965 Ghia and finished third in class even losing two days out of seven to suspension repairs.

We did it on 28mm vents.

I used the 31mm vents on our high compression 1.6 first road race engine on our 1970 Ghia, and upgraded to 34mm vents when we went to 2.2 litres. I swapped over to EMPI-Weber 44's then to pirate the Kads for Mexico.

The Kad advantage is great low and mid-range performance, and very little tinkering and tuning, which means more time driving.

Make no mistake that a Weber or Dell type 2-bbl is better on the top end, but here's a video of us top-ending Kads to all they can take on our 1.6

http://www.youtube.com/watch?v=u1d3Swrn-YI

FJC

[Merlin]

Hey FJC,

I'd rather stick with the tried and trusted method. I'll check for IRS torsion bars here, but will try the current setup with and without sway bar too.

I'm considering (when possible) changing to single-springplate setup too.

I believe you can simply grind off the second springplate?

I've got a list here somewhere of what's involved...

Would that bring my rear wheels in a bit? They stick out about an inch of slightly more, at the moment!

The Kadrons were all that was available, so I took them, with a butchered Scat linkage, which we're making work. We had to extend it.

It's got EMPI cast manifolds, and stock heads. Everything was ported, by the same guy who built my engine.

CR is 8:4

Cam is a 110-equivalent.

With regards to vents, that's up to my friends to help sort out - I have not a F'ing clue what all of that is.

I just drive.

Nice vid' - sounds manic.

Cheers, Nic

[FJCamper]

Hi Merlin,

The spring plates on an IRS need to be double, because they are no longer spring plates (a swing axle part) but location arms.

The swing axle spring plate was both locater and torsion spring, flexing sideways as it moved up or down.

FJC

[Merlin]

An IRS springplate still twists though[?], although nowhere near as much as a single.

I was under the impression that duals were used due to the heavier weight of the Autos[?] and Type 3s they were initially designed for?

IRS went to singles on the bugs from '69, afaik?

I've found someone in my country with the right camber adjusters and will arrange to ship them asap.

My bug builder and I have agreed to drive the car as-is for the next 2-3 weeks, to get everythung run-in, before tinkering with changing out the Type 3 torsion bars.

Thanks, Nic

[FJCamper]

Hi Merlin,

Porsche stayed with a single spring plate on the 911's (the original 901) when they went to the four-joint rear suspension in 1964. Weight was a consideration, but they really got by with it because of some nuances in the diagonal arm to chassis mounting angle.

VW opted to double the spring plates on the 1969 model year cars when they went to IRS, because the double plates gave extra lateral support and it was an easy design change. It had nothing to do with the vehicle weight.

The VW rear diagonal rear arm bolts to and pivots off the chassis at a slight angle, and this causes some spring plate flex as the suspension moves up or down.

The IRS has a lower rear roll centre and this sideloads the suspension more in a hard corner.

FJC

[Merlin]

Hi Merlin,

Porsche stayed with a single spring plate on the 911's (the original 901) when they went to the four-joint rear suspension in 1964. Weight was a consideration, but they really got by with it because of some nuances in the diagonal arm to chassis mounting angle.

VW opted to double the spring plates on the 1969 model year cars when they went to IRS, because the double plates gave extra lateral support and it was an easy design change. It had nothing to do with the vehicle weight.

The VW rear diagonal rear arm bolts to and pivots off the chassis at a slight angle, and this causes some spring plate flex as the suspension moves up or down.

The IRS has a lower rear roll centre and this sideloads the suspension more in a hard corner.

FJC

Hey FJC,

OK, that makes sense to me. I have noticed that the brackets welded to my pan are at an angle.

Couple of questions...

1. Excuse my ignorance but regarding your last line (sideloads), is that a good or bad thing?

2. What changed that VW went to single-springplate IRS a year or two later? ...before anything is incorrectly assumed, I'm genuinely interested and am not bugging you about this for no reason.

Many thanks, Nic

[FJCamper]

Hi Nick,

Sideload is lateral forces on the suspension pushing everything to one side. In a good high-G turn, you've got a lot of sideloading.

I honestly don't know why VW changed spring plates like they did, except for cost or engineering reasons to make greater parts compatibilities between models ... and then I still don't know. It wasn't to change handling.

I prefer the double spring plates for the strength, but the 911 single plates got the job done.

FJC