Advanced Suspension Mods

[fasteva]

this was really helpful thanks for you expertise !!

[Advancedynamix]

It's been too long since I've updated this, and a lot of you guys have PM'd me with pretty much the same questions, so I'll do my best to answer them for everyone.

First off, this suspension setup has been in use now for over 2 years, from sea to sea and on half a dozen road courses. I have learned a thing or two and I've changed things a bit from the original write up. Here is a list of changes.

On my latest rear shocks I no longer shorten the rod that holds the lower shock mount. I simply remove 3" from the shaft itself in a similar procedure. I cut a 3" portion from the upper part of the shaft just under the stock bumpstop locator (raised portion where the chrome plating stops). I then face and drill/tap both parts and cut a .125" 45 degree chamfer in the lower portion for a weld fillet. I then use a grade 8 stud (1/4-28) to thread the top back on the shaft and I weld (GTAW) the shaft back together using ER70-s2 filler in accordance with AWS D17. I don't show pictures of this, because If you can't decipher these instructions you shouldn't be performing this mod to a shock absorber, but there are people in your area who most likely can do this properly.
On shortened shaft KYB shocks I run 8" long southwest speed 150 LB 1 7/8 I.D. springs for just about all situations with the sleeves I showed in the original portion of my writeup. These 150lb springs are the most versatile setup I've found.
On unshortened KYB rear shocks, you must use the longer 10" springs. I have found that 120lbs is a good rate for these springs. Since your car will have more suspension sag, you need a lighter rate. the wheel pressure will be nearly the same with the 120lb 10" spring as it is with the 150lb 8" spring. because you'll have 3" or more (depending on load) of sag.

Front spring rate: I suggest a 200lb spring with the VW MK2/3 struts on a car with a g-series trans (all B series engines). On E series trans cars you may want to go with a 175 lb rate. The reason for this is because the g-series tranny mounts the engine atleast an inch further forward, and it weighs a bit more than an e-series. Believe it or not, this dimensional difference is equal to almost 100 extra pounds of pressure on the front tires. Don't run 100 less lbs of spring rate though, springs don't work like that. We work with percentage values on spring choice, not lb for lb figures.
I use 10" springs for most applications. For those who want a slammed low car, I suggest 7" or 8" springs with filler coils. Since the shock length isn't changing and the filler coil is giving you your sag, no spring rate change needs to be made for the shorter front springs.

Okay now for things I've worn out or broken.
For street use and street tire track use stock rubber bushings in everything are perfectly fine (given your bushings are in good shape). For R-compound or Slicks with a G-series and over 120HP you'll notice LCA inner bushing displacement issues, especially on the passenger side. I found Poly LCA replacements are available in Australia for reasonably low prices, but shipping is a bear so you'll want to group buy on these or find a comparable u.s. distributed product. My poly bushings have held up well, but gave no noticeable (I measure performance in milliseconds and exit speeds) increase or decrease in performance. The car just holds it's alignment now, when I push it to the limit. Those in colder climates may not have the LCA bushing problem, I run my cars at temps well above 100 degrees F. In climates where the car will be driven in sub 0F weather I strongly discourage the use of polyurethane bushings as Poly can become brittle at low temps. I had lots of issues with this when I lived in Maine.

Brakes: I originally used Capri XR2 front brakes and Festiva rear drums. I have since swapped to Aspire Auto Front brakes and I drilled my festiva drums for 4x100 pattern. The Aspire brakes work much better than the capri units, I had problems with my capri brakes hanging up and heating up. There are much better pad choices for the aspire as well, but you can run aspire pads on capri calipers. I use Performance Friction Sport compound pads on drilled ebay rotors and I'm still on my first set (thousands of track miles and way more street miles). I made the switch because I wanted to run 13" wheels for my R-compound tires and slicks.

Camber Adjusters: I am on my second generation of rear camber adjuster/spacers. I'll post up some drawings and pictures of what they look like. I don't think I'll go into production of these, because the small market just means I'm paying out of pocket to get everyone trick parts and I can't do that. However, I will make a couple sets whenever I need 1 set, so I'll probably throw a set or two up on the for sale forum from time to time. Festivas Love negative Camber, and hate toe. Ride quality, fuel mileage and performance will increase with -2 degrees or more camber in the rear and wider tires fit under the fenders too! I have had zero wear issues because the toe is what wears tires, not the camber and I run mine at 0 degrees toe on all four corners. Since there is no scrub, the tires roll easily and don't wear quickly. I corner very aggressively all the time, so my tires wear very evenly. For people who don't drive aggressively then normal tire rotation should even out the wear.

Tip: learn how to align your car yourself. I fix peoples alignments all the time who have payed "laser alignment rack" places a lot of money to mess up their cars. It just takes simple tools and it can be done quickly. I fixed the alignment on 2 cars at FM6 with just the tools that I had with me for the show.

For all those who have been waiting for me to produce this suspension I must apologize. I can't do it at a fair price. I build these cars as a hobby to relax from the rigors of work and if I turn this into work then it will no longer be a hobby. I will however give any and all advice that I can for free. There are talented people who can perform these mods in most towns and cities around the world. I can't go anywhere without bumping into fabricators and most will do side work for beers, so no excuses! This suspension setup is cheap when compared to what it turns a Festiva into.

[fastivaca]

Thanks for the update Charlie. Could you do a write up on the DIY alignment? Are you running with stock camber in the front?

Cheers

Sent from somewhere west of here via Tapatalk!

[moz]

Thank you charlie!!! My rear suspension is now complete.
Will do engine swap then front suspension.
I have my coilovers here already.

I refer to this thread before starting work every time.

Very grateful

[moz]

If I may ask....

What brand bushings did you use on your LCA?

And also, what type/brand/model bump stops did you use in the rear?

I'm finding that all the bump stops I've tried need to be trimmed down to fit inside the coilover sleeves in the rear. Is this normal practice?

[Advancedynamix]

Thanks for the update Charlie. Could you do a write up on the DIY alignment? Are you running with stock camber in the front?

Cheers

Sent from somewhere west of here via Tapatalk!

Ian, I am usually in such a hurry when doing my setups that I forget to take pictures, but I'll do a quickie on aligning a festiva, stock there is not much to adjust really, just toe and camber with the strut mounts. I run -2.5 degrees camber in the front as well with 0 toe. This car is awesome because those settings work great with my R compound tires, my slicks and I ran those settings continuous for 6K miles across country and back on brand new tires and experienced no noticeable tire wear. Gotta love that!

If I may ask....

What brand bushings did you use on your LCA?

And also, what type/brand/model bump stops did you use in the rear?

I'm finding that all the bump stops I've tried need to be trimmed down to fit inside the coilover sleeves in the rear. Is this normal practice?

Thanks for the kind words, I'm glad this thread is helpful to so many. I prefer the bumpstops sold for VWs like the Mk3 Mk4 or new beetle. I buy them by the dozen and cut them to all sorts of different shapes. It's okay to trim them for your application. I find the VW ones are the easiest to trim and are very long to start with. the front bump stops are not as critical as the rears.
Here is a photo of the inner LCA bushings and the invoice. You could probably make a killing by hooking up with these guys and selling them to us over here. they are a really nice part with internal knurling to hold the grease.

[kumalaba]

awesome!

[TominMO]

Charlie, have you by any chance looked into the idea of adapting the IRS setup from an early-90s Protege to a Festiva/Aspire? It seems to me that a pretty simple subframe could be built to hold the parts. The Proteges with BPs had rear disc, and those cars were 4x100.

[Advancedynamix]

The festiva has a much more efficient and light weight independent rear suspension than any other Mazda or ford car (sold in the U.S.). Any other suspension would be a down grade in performance and would add weight to a very critical area of the chassis. If you want proof of this, jack up the rear of your festiva and suspend the rear on jack stands. Now, remove the lower shock bolt on one side (I know this is a day long project for some of you and I feel your pain, I grew up in the rustiest part of the country). Now, with your hands, lift up and down on the rear wheel on this side. see how easy it moves, this is because it's independent. It actually moves easier than the IRS setup and it's lighter. Now for the kicker, when this beam flexes, it offers 3 wheel steering! That means the harder you lean a Festiva, the sharper it will turn. The trailing beam suspension is the ultimate setup on light weight performance orientated FWD cars, and this is obvious throughout history at the track.
As far as rear disc brakes are concerned, I see no need for them. My braking is balanced and controllable with almost no fade at limits that make most sports car enthusiasts literally speechless. I can run similar lap times to a professional driver behind the wheel of z06 corvette for hours on end and still put my hands on the rear drums (don't put your hands near the front brakes though) meanwhile the corvette driver is complaining about brake fade and tire fade and engine heat! There is video proof of this.
The benefit to the stock drums is that they are light and simple. If the components are in good condition and are adjusted properly they do a fine job, even with hot sticky racing slicks and 100 more HP than stock.

If I were to do a rear disc setup, which I may in the future. I would design my own light weight trellis style trailing beam, and I would use sprint car style direct mount hubs and wheels to keep weight to an absolute low. Any weight behind the front axle center is a bad thing on a FWD car. The more lbs I can shed back there the less I have to slow down for corners. Weight in the back of the car makes it want to spin in circles rather and follow the front. Ideally I should never have to lift off the "go pedal" longer than a few seconds to set the front for turn in, it's all acceleration from then on out.

[TominMO]

Thanks for the edumacation. I'll leave it alone then....

[Advancedynamix]

For those who haven't seen the proof. This was on almost bald Toyo's, on fresh rubber I would have walked away. Near the End of the video I try to let the Vette by because my tires were getting downright scary, I slowed down a lot but Justin (corvette driver) got confused and missed his braking point and went off the track. After that we catch some lap traffic (Porche 911 that spun off the track, Fox Body Capri, and Maserati) There was no one in front of us that wasn't lap traffic.

http://www.youtube.com/watch?v=RFOtP0wnXVY

Here is video of the session before, when I caught the Vette (tires still had some love left in them).

http://www.youtube.com/watch?v=cmdb2pkxOLM

The only time I could see the need for more rear brake and a rear subframe with IRS is if you were towing a large trailer or going AWD. At that point I'd just build my own multi link and tie it into a roll bar.

[Advancedynamix]

Thanks for the edumacation. I'll leave it alone then....

Your welcome, it was a great question.

[moz]

[/QUOTE] The benefit to the stock drums is that they are light and simple. Weight in the back of the car makes it want to spin in circles rather and follow the front.[/QUOTE]

so is there any advantage in using the aspire rear beam?

Everyone refers to it as an upgrade. But it does weigh roughly 10kg more than the festiva one.

[Advancedynamix]

[/QUOTE]

so is there any advantage in using the aspire rear beam?

Everyone refers to it as an upgrade. But it does weigh roughly 10kg more than the festiva one.[/QUOTE]

Yes and no. It will make the car feel more stable under hard cornering with stock length rear shocks, but the extra weight is more of a deficit than the added stability. On the limits, the car will actually corner faster with the stock components, but it will feel as though it's going to flip over so most drivers will slow down. Driving fast with body roll is an art. Rally and offroad drivers are forced to learn how to use roll to their advantage because they can't sacrifice travel or bump absorption. Road racers and autocrossers tend to want to remove suspension from the driving equation. This isn't usually a problem with autocross, because cones are soft and if your running them over your going to lose time anyway. However, with road racing there are bumps and dips and curbs and sometimes ruts and snakes and rabbits and dogs and children... oh wait, no don't run those over! lol. Anyway, learning how to use body roll as an advantage will make anyone a better driver, because suspension is important.
Instead of switching to an aspire beam, I would find shorter shocks. Try KYB gas adjust shocks for a MK1 vw. I have a set but havn't tried them yet. They are shorter with stiffer compression dampening and will accept the 1 7/8 coilover sleeves with less modification than the aspire/festiva shocks. Again, I havn't bolted them up, these are just an example of trying to find a better solution than anti sway bars.
Anti sway bars limit the suspensions ability to independently absorb irregularities. They sort of solve one problem, however create a few different problems. They increase unsprung weight and slow the suspension action down, they cause the chassis to upset more easily and they add complication when servicing the suspension (not the Aspire bar, but on most cars). I prefer to tune chassis without using sway bars. The OEM uses them because they have to design and build cars that will be used in so many different locations by so many people that they have to have lots of travel, lots of ground clearance and still be able to turn a corner with 5 people and their luggage. The Festiva/121 chassis is a perfect example of this. These cars have 3" too much shock length for any sort of performance tarmac driving. Take that extra length out of the picture and these cars are phenomenal in corners. They still have plenty of ground clearance and absorb even large bumps with no problems, but are rock solid stable when destroying tires around corners at speed.

[TominMO]

OK Charlie, another question: since your Festy is set up for nice smooth tracks, the stock rear beam is fine for you. But might not IRS be better for street driving, even if the penalty is heavier components? (This could be somewhat mitigated by light wheels and tires, like VXs and a 40 to 50-series tire.)