Advanced Suspension Mods

[Safety Guy]

Thanks Moz!

When I get my KYBs I'll measure their OD to make sure.

Karl

[moz]

Hey karl.
I bought the same set up.
The link below is for the same sleeves, only they seem to have a different nut without the locking grub screw.
If not sure, i would buy the afco branded one.

But speedway are the people selling these items.

http://www.speedwaymotors.com/Pro-Shocks-C375-Coil-over-Kit-for-SBA-Small-Body-Shock,846.html?b=r*Shop*Suspension!r*Category*Suspension%2c+Springs+and+Related+Components!r*Part*Coilover+Adjustable+Spring+Lowering+Kit

[Safety Guy]

Charlie, when you get a chance, could you post a current source for the "small body shock sleeves" you recommended at the beginning of this thread? The ebay link has run out and I couldn't figure it out myself.

I'm ready to redo my work car's rear suspension so I can haul loads, pull trailers and raise and lower it accordingly when I'm not hauling stuff. So far I have:

KYB Festiva spec rear struts.
Black Magic 10" x 1 7/8" rear springs (150#, from SW Speedshop)

I figure I can (carefully!) cut and grind off the spring perch on the KYBs myself. I'm keeping them full length since "ultimate handling" is not the goal. Is this all I need to do to install the small body spring kit?

I'm dropping my 13 wheels for 14" Miata wheels and 185/60-14s for ease of replacement on long trips should a tire be destroyed. I'm thinking "long term" use since I may not always be able to get the 175/60-13s I'm running now. I also plan to go to later model Rio 10" disk brakes for heavy duty braking (ie, pulling trailers), which will require 14" wheels.

I may have further questions on running Rio front struts and converting them to coil overs in the near future, but my cut Aspire springs on Rio struts are fine for now.

Thanks,

Karl

[TominMO]

OK, I'll shut up now........thanks for the further clarification.

[defprun]

I like the cut of your jib boy!

[Advancedynamix]

My car isn't setup for smooth tracks. In fact I hammer washboard dirt roads quite regularly with both my Festy and my Capri which has the IRS you speak of. The festiva absorbs bumps much better. I spent a good portion of my teens and early 20s building rally cars and the MK2 VW was a FWD force to be reckoned with. Now the FWD rally weapon here in the states is the fiesta, which also has a trailing beam. A trailing beam is independent, like I explained before, and its natural arc is one that follows the ground better than a multilink. Look at the off-road world to see trailing link/trailing arm/ swing arm and swing axle designs that are congruent with a trailing beam. The festiva is nearly flawless in this aspect. It is like A lighter and more rigid MK2 VW, but it's also shorter and therefore much much faster around corners. The Chase car on my " the hills have roads" video was a 2.0 turbo swapped mk2 that was set up and driven by Chris Duplessis' (Ford sponsored rally America driver) mechanic Brandon, and he slid off the road several times trying to keep up. I wasn't pushing the festiva at all. That same video shows how well these cars handle on rough roads and dirt. I jump my cars regularly and haul loads that exceed what the factory intended. The little festiva is a miracle of automotive design just the way it is.

Again Tom, I think there are a lot of members with the same questions, so thank you for asking. I will go into more detail when I continue my " festiva advantage" write up.

[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.)

[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.

[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]

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

Your welcome, it was a great question.

[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.

[TominMO]

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

[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]

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.

[kumalaba]

awesome!