Lowering (again!)

[ray greenwood]

Sparky...sorry it took me so long to get back to you....its been busy! The threaded perch designs that are out there have a second outer tube welded around the inner existing strut body...or just a thicker tube that is threaded. You will need to carfully remove the lower perch...a dremel with a cut-off wheel or carbide burr will do. Then smooth the area where the perch was welded. The perch itself in most designs is actually replaced with the equivalent of a large shaft collar (like a split drill collar bushing). That way you can tighten the cinch screw to make sure that the color does not rotate down. a piece of threaded pipe is slipped over the existing strut tube and welded in place. If perfect micro-adjustability is not necessary...carefully remove the existing perch...weld on a steel strengthening ring or seat at the bottom hole....weld three lugs about 3/8" thick and 1/2" wide onto the strut tube...spaced at 120 degree intervals...at the correct spring perch height that you now require...and notch the bottom hole in the original spring perch to fit the spacing of the 3 lugs welded onto the tube. Slip it over...turn it 1/3 turn so the notches are now past the lugs and it is resting on them...then lock it with a set screw. You could weld on any # of layers of lugs for adjustment points either higher or lower. I will e-mail you the stub design today to use the Audi 4000 cartridges. Sorry I have been away...I am working a little over 100 hours a week right now....and I destroyed the engine in my 412 last weekend...so my time is evaporating for the moment. Ray

[herr_sparky]

ray--the cup is to be turned off on a lathe, and the simplest thing weve come up with is to just TIG weld it back in place wherever I want it. In that case, it'd need to be a good guess for location.Id rather have the flexibility of an adjustable perch, but the complexity...my questions: index the cups relation to the strut body/upper cup? In terms of the effective stroke of the damper, how much overlap? I dont want more than 1.5 to 2 inches of drop. If Im picturing the way all this works together right, wouldnt the pushrod stick up through the body and eventually hit the hood? can you chose various damper overall lengths? Also, I dont think any of the bits that came off the strut tower tops are type 4s. They dont look like anything in any of my books, but it is a '74. By "oblong" do you mean the bolt pattern is not symmetrical? thats what Ive got, and a bronze colored cartridge bearing, like a deep saki cup, and a rubbery grapefruit-sized ring with the part # 823 412 355. on top is the nylon friction ring, cracked, and the uppermost metal cup underneath the center nut. I cant figure out what Ive got here. I suspect Im missing some parts.

[ray greenwood]

Hey sparky...The step on the strut rod..and the spacers it uses are what keeps it from sticking up too far. Lowering is great, but unlike lowering cars where you cut the springs down, there should be very little need for increased spring rate. The adjustable perch would be great for keeping the same load rating on the springs. The type 4 was oversprung...but horribly under damped. This is why it rolls in turns so heavily. Actually the rebound stroke is the weakest. It quickly destroys the compression stroke as well because of speed of movement. On the stock 412 strut cartridge...you will find that only about 5.5" of total rod are used during minimum and maximum stroke. The rod is simply long...as well as the whole strut assembly...because the mounting placement in the body is so high. There is a larger amount of unused rod capability. But...you have noticed the problem of lowering and using the stock cartridge. Since the piston being at full extension dictates the stroke length..and the stop point for the spring...you cannot simply lop off the top part of the rod...and there is no place for it to protrude into the trunk. You need a shorter cartridge...with correct valving. Ths audi 4000 in KYB GR-2 is excellent for that...but wihout a stub, it will lower you almost three inches. Without moving the bottom perch...it will compress the spring almost 3 inches. What you can do...is move the bottom perch to keep spring compression stock..and make an adapter ring to bolt the strut bushing too...that in turn, bolts into the body where the strut bushing does. Its thickness will actually dictate the lowering. It could be 3 inches thick...giving stock ride height...or 2" thick giving one inch of lowering. If you make it right...it could be a stack of plates with through bolts...so you could remove them a 1/4" at a time. The stub design I made actually lowers the front end about 5/8" to 3/4"...so its level. The other design for a stacked plate assembly would work great...but would add unsprung weight to the front end...which might not be a bad thing...Ray