simon's learning what to do with the polo thread

[sambb]

That, or keep the stiffer rear springs but change to a softer rear bar like UR's 18mm rear bar. Either way if you take a bit out of the rear so it doesn't lean as hard on the fronts, it will tell you something. On B8's I had either stock or weitecs (both stock rates) fronts, rear H&R's. For bars I had whitelines- front 22mm set to soft and rear 20mm set to hard. I never really ran the front on hard. I always felt like I needed more rear bar.
The H&R front bar is only 20mm from memory up 1mm on stock. Would probably be great if you had a lot more spring in the front but since you don't (and may not find a spring with substantially more being locked into a strut) , something like Ultra racings 23mm FARB Volkswagen Polo (9n) 1.8t Ultra Racing Front Anti Roll Bar UR-AR23-316 Only £217.26 would probably get the front more in line with all that roll stiffness at the rear. Or the whiteline that has the benefit of being adjustable - you never know you might hit a sweet spot where the soft setting works with the H&R rears and the hard setting works with the stiffer rears. You could see how you go with sourcing stiffer fronts whether you go with a modified strut spring or change the strut to accept 60mm ID coils. If it looks like you might be able to get a stiffer spring in the front I'd hold off on a front bar until you've tried it out. If you feel though that you are locked into stock'ish spring rates at the front, then yeah a FARB will help things. In the short term its probably cheaper/easier to run the H&R rear springs, throw a front bar at it (a bit of work though), and bung some rear toe out into it.
If you do go to 60mm ID coils on the B8's I have a pair of 150mm long 7kg fronts you can try (MCA's) for minimal $erage. Those fronts with a stock front ARB might marry up well with your stiffer rears and mutant rear bar.

[sambb]

If you look up H&R (australia) it'll link you to their international catalogues. From memory you can see their weight over axle ratings for the different springs. I'll try to dig out the email address I got for one of their peeps in the fatherland who has told me the actual spring rates of their springs in the past. I wonder if a Golf had the same ODmm springs and seat dimensions as us but had longer free lengths. Maybe a tour though a wrecker could tell you if a Golf spring with a coil lopped off would fit.

[simon k]

I like the idea of converting the B8s to coilover, there are plenty of different adjuster sleeves out there. If springs are cheaper and easier to get once converted, then it's smarter in the long run...

I have options, I'll weigh them up, fail to make a decision and talk about it again in a couple of months

....bung some rear toe out into it.

talking of rear toe, you had success with them, but I reckon those Eibach shims are sh~t. For starters I reckon their measurement table thing is arse about left to right (or positive to negative toe), then by the time I'd cut out enough of the fingers to clear the top bolts and the ABS sensor there was only one finger each side, which crushed torqued it up - I took it back out and those top fingers snapped off - stupid thing...

I'll make up a mounting plate to hold my rear plates in the lathe and machine them

[sambb]

Yep they are turd - fragile and finicky and definitely a one fit only. I didnt trust that they'd stay put either so I've had the hubs off to check the torque I'd left them at and done lots of toe/ camber checks and they have been solid. Yeah you have to be really careful with them when you prep them for fitment. You really need a bench grinding wheel to take out the relief for the ABS sensor as cutting it is next to impossible as the cut just tracks into the next tear strip. And yep interpreting the quadrants and remembering to flip one of them to the right orientation before you cut out the abs relief is another trick. I've done it twice now and have it sussed but I ballsed up my first attempt too. Its enough to make you lucky if you get it right. Terminology like "to add - camber" has you thinking will that take camber on or off. I can take a photo of what quadrants to be in. Get some alignment numbers off a shop and we'll work out what to do
Definitely well worth it. Its the most noticeable thing I've done up there with the rear bar. You really do go WOW when it just rips through corners that would have had another 30 degrees of steering lock on before and I haven't found it to be hairy at all on the circuit in higher speeds stuff eg Griffins bend on cold tyres at Bathurst

[simon k]

Yep they are turd - fragile and finicky and definitely a one fit only. I didnt trust that they'd stay put either so I've had the hubs off to check the torque I'd left them at and done lots of toe/ camber checks and they have been solid. Yeah you have to be really careful with them when you prep them for fitment. You really need a bench grinding wheel to take out the relief for the ABS sensor as cutting it is next to impossible as the cut just tracks into the next tear strip. And yep interpreting the quadrants and remembering to flip one of them to the right orientation before you cut out the abs relief is another trick. I've done it twice now and have it sussed but I ballsed up my first attempt too. Its enough to make you lucky if you get it right. Terminology like "to add - camber" has you thinking will that take camber on or off. I can take a photo of what quadrants to be in. Get some alignment numbers off a shop and we'll work out what to do
Definitely well worth it. Its the most noticeable thing I've done up there with the rear bar. You really do go WOW when it just rips through corners that would have had another 30 degrees of steering lock on before and I haven't found it to be hairy at all on the circuit in higher speeds stuff eg Griffins bend on cold tyres at Bathurst

setting up the shims wasn't the issue, it's just the general ****tiness of the approach I don't like - I already had alignment figures from when I got tyres & alignment done, I confirmed they were still correct with a stringline and CAD alignment model of the geometry, worked out exactly what angles I wanted, then used trig to get the right shim thickness to make those settings... if the bastard thing hadn't fallen to bits it'd be in the car now... I guess where I went wrong the most was that I cut out the whole section to clear the ABS sensor (as per the diagram) instead of using my dremel and a sanding sleeve to take out only what it needed... so I have one disk shim thingy that is uncut, and one that is probably rooted. Not fussed, like I said, I'll set them up in my lathe and do it properly

I just found these articles linked by Greg - doesn't this one sound familiar!!! TDIClub Forums - View Single Post - What is Handling?

but a big rear bar will only reduce the initial amount of roll. At some point, the inside rear wheel will lift (it'll lift on even a well-driven stock car), and when that happens, it really doesn't matter whether there's a big anti-roll bar in the back or not: as far as the car is concerned, there is one wheel on the ground in the back, and two wheels on stock springs and stock bar in the front. Hence at the dry-road 3-wheel cornering limit, a big-rear-bar car will understeer about as much as will a completely stock car (note: there's actually a bit of a difference in that a big rear bar will, by lifting the inside wheel higher, cause more leaning of the outside wheel, but there's so much understeer built into the stock suspension that the overall result is still understeer). Now, this is a fairly horrible handling set up (understeer sets in rapidly the moment the rear wheel leaves the ground), but there's no oversteer at the limit.

this exactly describes what it's like driving my car - once it's up on 3 wheels it doesn't matter what I do to get it to rotate, it just keeps plowing on... it was probably better at Winton when I was there because at least some of the corners are properly cambered, the track up here is pretty flat. It's used for competition on the weekends, but it's primary reason for existence is to train truck drivers

On one of the first corners yesterday I had a smidge of oversteer and I thought "excellent, it's finally going to handle properly", but then the tyres warmed up and it was back to tricycle city. I have scrub marks on my tyres almost all the way down to the lettering

[sambb]

ha ha yep mine was a dog like that too. Yep that's why getting the f:r roll distribution so that the inside rear feels like it skims the deck is the way to go. The rear toe will get that rotation thing happening. As a bodge you can pump up the rears so they are running on their centre lines more and then they will start to slide more. In comparison to what I have now, a stiffer front bar will get you out of trouble but the car will still pitch forward in the same circumstances. It'll roll less but the nose will still be driven downward and you still get that feeling that you are just eating through all your (limited) front camber and once its gone you are pig understeering again so you have to be really careful not to go in too hot. The stiffer spring rates really do change things as the car doesn't pitch and heave and stays sled flat - but by then you have no comfort!

[Sydneykid]

You guys have been busy while I was away in Alaska some short comments follow;
I wouldn't use a circlip style (height adjusting) sleeve on a strut, they are OK for double wishbone, where there is no side loading on the shock (strut) body. We use weld on sleeves, which means removing the damper from the strut body as they don't like welding temperatures. Bonus is that strengthens up the strut body so it doesn't bend as easily (retains camber).

There is a direct correlation between the spring rates and the amount of camber required. It's all about maintaining the tyre contact patch as the chassis rolls ie; softer springs need more neg. Keeping in mind that if the lower control arms are level (parallel to the ground) or point upwards towards the wheel then it will lose camber as the spring compresses, AKA a regressive camber curve. What is desirable is progressive camber curve, adds negative camber as the spring compresses to retain the tyre contact patch as the chassis rolls.

The theory of increasing the rear roll stiffness only helps understeer until the diagonal weight transfer gets excessive (insufficient negative camber) ignores the turn in advantage that increased rear roll stiffness provides. ie, we don't need to turn the steering wheel for as long and/or as much.

Run out of time, sorry, I'll get back to it when i can.

Cheers
Gary

[Sydneykid]

Each tyre has a preferred spring rate, that's effective rate, what the tyre feels. For us A050's work best around 300 to 350 lbs/inch as an example. So with, say, 0.9 leverage and movements ratios (MacStrut) that means a spring rate around 370 to 430 lbs/inch (6.5 to 8.0 kg's/mm). That's quite a bit of spring for a road car (think handling not comfort) but we can run a fair bit less than that if we have enough bump damping coupled with enough anti roll. For a FWD car we need to be cognisant of not having too much anti roll on the front as it limits inside wheel traction. Which is not a problem on the rear of course.

Generally speaking most FWD "sporty" models have a reasonable amount of front anti roll standard, so I tend to limit them to small swaybar upgrades on the front, if at all. Again not the case with the rear of course, where I haven't found the limit on many cars.

With a combo road and track car what I have found is a compromise on spring rates can be compensated for with lots of caster which has no handling downsides compared to lots of neg camber (wears out tyres real fast, increases braking distances, reduces acceleration traction etc). I have had road cars with 9 degrees of caster and only 1 degree of neg camber that handled pretty well on the track and had pretty good ride comfort at the same time. So my suggestion would always be to crank on as much caster as physically possible and then add camber as required. My rule of thumb is 10 degrees total, say 9 caster plus 1 camber, 6.5 caster and 3.5 camber etc. That's where I start on sedan based race cars.


As we increase the front traction (via tyre contact patch) we find that less steering lock is required for a shorter amount of time. We can straighten up the steering wheel earlier for a better corner exit, get on the throttle earlier and harder, which as a bonus makes the straights longer. Rear toe out is anther big help for the same reasons.

With 10 degrees total it shouldn't be necessary on road tyres to have an effective front spring rate more than 150 and 200 lbs/inch (depending on the tyre). Provided there's enough rear anti roll and toe out. A small increase in the front anti roll won't hurt.

In summary, we can get away with softer than ideal spring rates, but we need to compensate with geometry. Plus institute a driving technique that gets the turning over early in the corner entry so we aren't hanging onto to steering lock deep into the mid corner and we are all straight by the corner exit. Late apexes don't hurt either.


Cheers
Gary

[Sydneykid]

A bit of shock theory.

Simplistically shock absorbers are "timing controllers", they increase the amount of time taken for suspension compression (bump) or extension (rebound), than springs with no dampers. We can use that as a spring rate substitute, but we also have to be aware that it's time limited. Even with drastically increased bump damping a car will eventually lean in long corner. If we "shorten" the corner (refer previous post) then the damper has a shorter time in which it has to limit the lean.

Cars with a "lot" of bump damping ride slightly better than cars with an equivalent "lot" of spring rate. Of course there is limit, where the bump damping still gets uncomfortable.

A good compromise road and track car is not easy to achieve and takes a full suite of "tuning techniques" to achieve. There is no silver bullet in that, doing 1 or 2 things isn't going to work magic, we need to use the full magazine.


Cheers
Gary

[sambb]

Hmm nice rule of thumb. I like rules of thumb. I can tell you on mine that the inside 1/1/2 in of my road Toyo R1R's are completely bald with 2.75 degrees of neg camber so more than the 6 degrees pos caster I have would be nice. Seems I'm a bit short of the magic 10 degree total
Gary does what you said about being able to soften the car off when the geometry is good hold true for the rear. Eg I'm about to properly space the stub axe out and re shim it in the process. If I go up from 1.6 degrees neg camber/ 2mm total to out, to 2 degrees neg/4mm toe, is it likely then that I could come back on the bar or springs a bit?

[Sydneykid]

Hmm nice rule of thumb. I like rules of thumb. I can tell you on mine that the inside 1/1/2 in of my road Toyo R1R's are completely bald with 2.75 degrees of neg camber so more than the 6 degrees pos caster I have would be nice. Seems I'm a bit short of the magic 10 degree total
Gary does what you said about being able to soften the car off when the geometry is good hold true for the rear. Eg I'm about to properly space the stub axe out and re shim it in the process. If I go up from 1.6 degrees neg camber/ 2mm total to out, to 2 degrees neg/4mm toe, is it likely then that I could come back on the bar or springs a bit?

Hopefully not, the extra camber and toe "should" result in faster times/higher speeds carrying more lateral G, hence more roll.

Yep, 2.75 is extreme for road car, can you use, say, 1 on the road and then flick it to 2.75 for the track?


Cheers
Gary

[sambb]

Yeah I can change camber easily with the MCA adjustable tops. I'll still be going through rears with 2 degree neg on the back though. I'm due for street tyres so I'll buy non directional so that I can move them around to eek a bit more time out of them.

[simon k]

I missed you Gary!! hope you had a great trip - Alaska is on the bucket list... the lady who usually signs my invoices at work is over there at the moment

I'm waiting for some photos to be posted from the event on the weekend, there should be some pictures of my tricycle...

Guesstimating some rear bar measurements, the 2" OD, 1.85" ID rear bar on my car is 10x stiffer than the 20mm solid bar sold by whiteline etc. - somewhere in the region of 2800lb/in against 253lb/in. My rear springs should be somewhere around 180lb/in effective rate against ~90lb/in for standard springs

That leaves the front springs and bar stock. Sam's opinion is that the rear bar and stiffer springs at the back are overpowering the front, so until I do something with the front, I should either keep the rear bar and try the softer (H&R) springs or remove the rear bar.

We use weld on sleeves, which means removing the damper from the strut body as they don't like welding temperatures. Bonus is that strengthens up the strut body so it doesn't bend as easily (retains camber).

Cost is a factor so initially I assume it'd be cheaper to find a spring that goes in place of the existing front spring, rather than buying the sleeves and springs... except the coilover springs may be cheaper on their own?

Converting the B8s to coilover means buying the sleeves and then suitable springs. Where you say "removing the damper from the strut body" it looks like that's just taking the nut off the bottom and unscrewing the insert (I found a video) - I don't need to let the oil out - which is good. Weld the sleeve top and bottom, repaint, assemble, install...

No doubt there are good sleeve kits and bad sleeve kits - do you have a recommendation? I'm not clear on what happens with the strut top/bearing too, is the standard bearing retained or do we need something different up there? Some sleeve kits come with a conical spring retainer, should that work with the standard strut top with the bearing removed?

I have more thoughts and questions but I've gotta run too - I started typing this at 10am, it's 5:30 now

[simon k]

oh, have you seen this?


vsusp.com with guessed dimensions

[Sydneykid]

I missed you Gary!! hope you had a great trip - Alaska is on the bucket list... the lady who usually signs my invoices at work is over there at the moment

I'm waiting for some photos to be posted from the event on the weekend, there should be some pictures of my tricycle...

Guesstimating some rear bar measurements, the 2" OD, 1.85" ID rear bar on my car is 10x stiffer than the 20mm solid bar sold by whiteline etc. - somewhere in the region of 2800lb/in against 253lb/in. My rear springs should be somewhere around 180lb/in effective rate against ~90lb/in for standard springs

That leaves the front springs and bar stock. Sam's opinion is that the rear bar and stiffer springs at the back are overpowering the front, so until I do something with the front, I should either keep the rear bar and try the softer (H&R) springs or remove the rear bar.



Cost is a factor so initially I assume it'd be cheaper to find a spring that goes in place of the existing front spring, rather than buying the sleeves and springs... except the coilover springs may be cheaper on their own?

Converting the B8s to coilover means buying the sleeves and then suitable springs. Where you say "removing the damper from the strut body" it looks like that's just taking the nut off the bottom and unscrewing the insert (I found a video) - I don't need to let the oil out - which is good. Weld the sleeve top and bottom, repaint, assemble, install...

No doubt there are good sleeve kits and bad sleeve kits - do you have a recommendation? I'm not clear on what happens with the strut top/bearing too, is the standard bearing retained or do we need something different up there? Some sleeve kits come with a conical spring retainer, should that work with the standard strut top with the bearing removed?

I have more thoughts and questions but I've gotta run too - I started typing this at 10am, it's 5:30 now

With an inverted shock just unbolt the shaft from the bottom and slide out gently, rattle gun is best. Then weld the sleeves (bottom only) on in the appropriate place, which means knowing what free height spring you are going to use first. I have a stock of sleeves and spring seats (top & bottom) plus lock rings. I just need to know the strut leg OD, and the spring ID, most likely 62 mm (2.5"). I have some new Eibach and H&R springs in stock of the right rate that might suite I just need to know the free height. With the dimensions I can let you know the cost. I may also have some used springs, when you send me the dimensions I'll check.

The top spring seat needs a spacer between it and the strut top so that the spherical bearing can articulate. I have plenty of different sizes, just need the dimensions.

Once you have a strut that can support race style parallel springs then there's an unlimited choice of spring rates. There's a cost at first, but it pays off over time.

I can't say as I have ever had a rear spring/bar combo that "overpowered" the front. You can get too much spring and then it gets nervous at the rear, especially under brakes. But that's about it. As a result I wouldn't waste time on "softening" the rear, spend the valuable time the front.

With a 180 lbs/inch rear spring (effective) rate something around 250 lbs (effective 200 lbs) would work OK on the front.


Trip was great, all the wildlife, whales, sea lions, bears, mountain goats, etc. Plus we dropped in at the Boeing factory in Seattle on the way home, bonus.


Cheers
Gary