Cutting my Festy's springs

[Advancedynamix]

Sorry to hear that Tom. How tight were your top nuts? The bushings should only have a little squish on them. If the nuts are tightened too much, the bushings can't move as the. The top of the shock needs to articulate fairly freely or the shaft will flex as the beam moves through it's stroke and articulates. There is a lot of movement at this pivot point.
If the shock shaft is flexing, it will prematurely wear the bushings and seals inside the shock.

[TominMO]

Sorry to hear that Tom. How tight were your top nuts? The bushings should only have a little squish on them. If the nuts are tightened too much, the bushings can't move as the. The top of the shock needs to articulate fairly freely or the shaft will flex as the beam moves through it's stroke and articulates. There is a lot of movement at this pivot point.
If the shock shaft is flexing, it will prematurely wear the bushings and seals inside the shock.

They were probably pretty tight, so thanx for the tip.

[Advancedynamix]

If the rubber bushings have become hard, they might be putting more load on the shock shaft. I use new bushings for a Miata. If you have already trimmed your shafts to fit with the interior panels then it'll be difficult to fit the new Miata bushings, but you may be able to use new bushings on the bottom and old ones on the top.

[fudge]

My VW KYBs ('91 Cabriolet, $33 each) came in today, so off to the McParts store to find a short exhaust pipe piece to raise the spring perch. The KYBs are built differently than the Bilsteins. The Bilstein body is 2" diameter, the KYB's is 1.5". The proper pipe turned out to be 1 5/8" ID; but it needs to be flared at the bottom for a proper fit, and shortened an inch or two at the other end. I will take it to an exhaust place to have them flared, along with the strut for test-fitting as we go. They can probably cut it easier and more precisely than I can, so I'll probably have them do that too. I'm guessing $10 total; we'll see. Pics tmw or Fri. The two pipe pieces cost me ~$7.

It occurred to me that I could just squeeze the bottom of the extension pipe I used on the Bilsteins, to get it to fit on there without using the spare spring perch, which looks tacky. Might try doing that by using an exhaust U-bolt fastener to squeeze it.

The bottom of the VW KYB is quite different from what we are used to on the Festy rear struts. There is a long metal tube sticking out of each side of the narrow rubber piece at the bottom of the strut. As Charlie says, cut 1/8" off the side that will go to the inside of the car, for more clearance. You could even cut more and use washers on the other side for a few mm more clearance, like he also said.

The spring perch KYB provides is perfect. Like the Bilstein's, you install it "upside down" compared to what our spring perches look like.

For all Festy front and rear struts of any brand, strongly recommend the KYB SB118 strut bumper and bellow. These are the good German ones. I tried it on the VW Bilsteins and KYBs, a Festy front KYB, and a Festy rear Monroe. It works well with all of them and easily fits inside both front and rear springs. Long bumper and long bellows keep out the water and grit from the strut shaft; and the bore of the bumper is large enough to fit all of these struts. On rear-strut applications, I used an extra rubber upper mount donut thingy to space the bumper/bellows assembly downward enough to put a little compression on the bellows, so it stayed permanently below the bottom of the shaft. For fitting onto the front struts, you might want to cut the topmost section (of four) off the bumper; it seems a bit long for the front. At Rock Auto, they list the SB118 for these cars. It's under $14.

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hey! reviving this thread to ask you a question! So you recommend the part KYB sb118 strut bumper and bellow for any struts we are going to use? I'm planning on ordering the ultimate street suspension kit soon and I was wondering if I should throw these in the cart too? Thanks

[TominMO]

hey! reviving this thread to ask you a question! So you recommend the part KYB sb118 strut bumper and bellow for any struts we are going to use? I'm planning on ordering the ultimate street suspension kit soon and I was wondering if I should throw these in the cart too? Thanks

Answered in the last paragraph. On struts with a larger diameter shaft, I have reamed the bumpers out with one of these spade bits designed to make larger holes in wood than a normal drill bit.

For the front, with narrow coilover springs, you will have to cut off the part of the bumper that does not fit inside the coil spring.