Cutting my Festy's springs

[Advancedynamix]

Good stuff here! Another note too. Miata rear springs are a heavier rate than the aspire rear springs. This is helpful info if you tow heavy loads with your Aspire or Festiva. This info is courtesy of Dragonhealer.

[TominMO]

Good stuff here! Another note too. Miata rear springs are a heavier rate than the aspire rear springs. This is helpful info if you tow heavy loads with your Aspire or Festiva. This info is courtesy of Dragonhealer.

How long are stock rear Miata springs? Measured just sitting on the ground. Same diameter as the Festy's?

BTW, when the VW KYBs came in they had very short, hard bumpers and a short, hard, smooth cover, not a bellows type. They are inadequate. Get the SB118.

[Advancedynamix]

Ryal is the man to answer that question. I am pretty sure they are the same diameter as festy/aspire springs. Ryal has them on his 91 that he uses to tow race cars and garbage around (trashwagon).

[TominMO]

What is Ryal's screen name? What is the rate of the rear Miata springs? I think the fronts are ~140, so I'm guessing ~110 for the rears.

[Dragonhealer]

How long are stock rear Miata springs? Measured just sitting on the ground. Same diameter as the Festy's?

BTW, when the VW KYBs came in they had very short, hard bumpers and a short, hard, smooth cover, not a bellows type. They are inadequate. Get the SB118.

The early Miata rear springs, paint code yellow/yellow, 1990-1993, are 9-1/2 turns absolute, 8-1/2 turns working, of 10mm coil stock. ID is apx 3-1/4, OD apx 4-1/8, a snug fit in the Festiva perch. Free lengh is apx 14-1/2, as fitted to Miata under load apx 8" as fitted to rear of Festiva apx 10-1/2
Best setup for this includes strut bump stop 1J0 512 131B from Rockauto.
use 65 to 90lbs. Toung weight, rear cabin ok to +300 lbs.


+1 Tom!

[Dragonhealer]

What is Ryal's screen name? What is the rate of the rear Miata springs? I think the fronts are ~140, so I'm guessing ~110 for the rears.

As I recall, I measured the rear early Miata springs and found 95lbs/in.

[TominMO]

Some new strut pics.

The Bilstein, ready to go back in. Even easier to install than the stock struts. Note extra spacing rubber donut at top, to compress the bellows. Color is washed out. The one in the background is more like it.


The VW KYB GR2s. Left one has spring perch in stock location, stock protector sleeve on top, and the bumper (which fits under the sleeve) sitting on the perch.
The right one has the exhaust extension piece in place. Needs slight widening at bottom. Sticker reads 1 5/8" ID X 1 3/4" OD. The OD fits perfectly into the bottom of the spring perch. Extension also needs cutting at the top.
I tossed the protector sleeves, and kept the bumpers in my suspension parts box. Get the KYB SB118 bumper and bellows, which I am about to order for these.


Closeup of the VW KYBs. They will end up on the Aspire.

[TominMO]

BTW these VW KYBs are much stiffer damped than the Festiva ones. I can compress any Festiva rear strut with one arm, but with these I really had to put my body weight into it.

[Advancedynamix]

The stiffer compression dampening is the golden ticket. The Festiva has an awesome chassis, but the standard valving rates are way off par. This car needs twice the compression dampening in the rear and twice the rebound dampening in the front than what it came with. If Ford had offered a sport tuned version of this car with a well tuned suspension and a 100hp engine, the world would look at these cars much differently.

[TominMO]

The stiffer compression dampening is the golden ticket. The Festiva has an awesome chassis, but the standard valving rates are way off par. This car needs twice the compression dampening in the rear and twice the rebound dampening in the front than what it came with. If Ford had offered a sport tuned version of this car with a well tuned suspension and a 100hp engine, the world would look at these cars much differently.

I suspect just about anyone would be happy with the VW KYB GR2s ($33). There is most likely no real need for anyone to go with the Bilsteins which cost almost 4X as much! Maybe if they are hardcore racers, in specific types of events the Bilsteins would be significantly superior--first place finish instead of 2nd or lower. Your thoughts Charlie?

I'll let you all know next week about the KYBs. I won't get to the muffler shop to mod the extensions until then.

[Advancedynamix]

The KYB shocks are such a huge improvement that the small improvement ( in comparison) will be hard to justify for most Festiva enthusiasts. The bilstein shocks will work better with a wider range of spring rates and will adapt to conditions better. The bilstein dampers also carry a lifetime warranty, so those of us who are lifers will appreciate that. If a Festiva or aspire is used for serious towing and the owner really wants to dial in the ride and spring rate, I'd suggest the bilstein shocks with adjustable sleeves.

One thing I'd like to clear up, that seems to be a big misunderstanding, is that the suggestions I have made on this site are for a street car, to be used comfortably on public roads. I test these components more on the street than on the track. Driving the car on the track only helps me to monitor the improvements I make in a controlled environment. The track is also the ONLY place to push the limits and see what can be done with a certain chassis. I still have yet to find this cars limits in street trim, but I feel confident in saying it's one of the top 5 best handling street chassis ever sent to this country. By "best handling" I mean the suspension can be soft and supple on the street while still being easy to control on the absolute limits. Tweak is a street car, not a race car. I sold it to a couple, with the same suspension settings I was running in those videos, who daily drive the car around San Diego, which is littered with nasty potholes and horrible road surfaces The couple who own it are a retirement age couple who own 2 93 Festivas, both with advance coilovers.
With that said, a race car needs to have suspension which is tuned to the drivers individual style on a certain coarse. The bilstein shocks would offer the widest range of dampening with different spring rates, but it would be best to have separately adjustable high/low compression and rebound.

[Advancedynamix]

The early Miata rear springs, paint code yellow/yellow, 1990-1993, are 9-1/2 turns absolute, 8-1/2 turns working, of 10mm coil stock. ID is apx 3-1/4, OD apx 4-1/8, a snug fit in the Festiva perch. Free lengh is apx 14-1/2, as fitted to Miata under load apx 8" as fitted to rear of Festiva apx 10-1/2
Best setup for this includes strut bump stop 1J0 512 131B from Rockauto.
use 65 to 90lbs. Toung weight, rear cabin ok to +300 lbs.


+1 Tom!

The reason Ryal gives all this information, but leaves out the rate is because this information is just as important, if not more so, than the rate when compressed 1" (or 2 depending on how you rate springs).
The spring rate alone tells you very little about how a spring will actually perform when installed. A good example of this is Pedro rides more harsh with stock Festiva suspension, than Babe with 165 front springs and 120lb rear.
How is that possible? Springs increase in rate as they compress. The 120lb springs in the rear of Babe aren't compressed in order to install them in the car. With the VW shocks, the car also has less than half the sag of a stock Festiva. Less sag means less rate rise as the shocks settle in to static ride height ( where the car sits at rest). This means that sitting on the ground, those spring rates are actually lower than stock, even though they are rated much higher.

[TominMO]

Had the extensions for the VW KYBs slightly expanded on one end and about 3/4" cut off the other end ($10, local exhaust shop). Plus $7 for the extensions, struts were $66 + shipping from Rock Auto; the SB118 bumpers/bellows were $28 + shipping. So I'm into this setup for the rear of the Aspire for about $130, with all top-quality stuff. Did all the painting today, and cutting the bottom of the strut mounts to fit. Assembly and pics tmw, plus a test drive. The VW KYBs are stiffer than the Festiva KYBs, damping-wise.

If/when these struts do finally die, all the work for new ones is already done. Buy 'em, paint 'em and cut the bottom mount, and slap 'em in with the extensions from the old ones. I always like to repaint even new struts with a longer-lasting Rustoleum; and I freshen up the spring's paint too. Not a pro job, but still way better.

[Movin]

I know I have an entirely different purpose but the monroe VW mkII struts with 125 lb 14" in front and the same in the rear with 75 lb springs are also a huge improvement over stock on the street. Monroe did not honor the lifetime warranty after I modified the spring perch for the adjusters. I did not ask but that info was given to me when I bought the replacement strut. The failure had nothing to do with quality or modification, it failed during off road use. Maybe bilstein would have survived I do not know. The MK II has more travel and the lighter spring rate takes advantage of that, my car "floats" on road or off when doing nasty bumps. The rio mounting stuff is nice and the wider lower mount is no big deal at all. Lighter springs and heavier shock rates rule!!....Off road and rough daily driver/

[TominMO]

More pics. Test drive tmw, as I am also doing some bodywork.

Strut on left ready to be installed. Note how the bellows and bumper completely protect the shaft from any debris.


Strut on right shows upper rubber donut replacement. I used one of those plugs in the hatch instead of the usual donut, because the donut was too thick. I went back and did this on the Festy too. Needed a 1/2" drill bit to make the right size hole. I also inverted the metal cap on top so it wouldn't rub against the body, with the shorter rubber peice.


I ended up using the black bumper that came with the VW KYBs as a spacer above the better bumper and bellows. It was just the right length.


The strut installed. I still had to use a 6m spacer, even with the 155mm-wide tire. But I have studs, so it's no hassle.