How To Section Struts

[Toysport]

Is this the right way to section front struts for the 240z-280z?

 

https://createpdf.adobe.com/cgi-pickup.pl/How%20to%20section%20struts.pdf?BP=&LOC=en_US&CUS=4c74bdebfb25ce22a79c31cbcac69eb3&CDS=425EE496-0B22-20F46D

 

I based my drawing from this: https://createpdf.adobe.com/cgi-pickup.pl/Sectioning%20Struts.pdf?BP=&LOC=en_US&CUS=4c74bdebfb25ce22a79c31cbcac69eb3&CDS=425EE703-50D6-18AF9E

[2126]

Well, you don't want to remove the top portion of the strut, because you won't have any threads to screw the retaining nut back into...unless of course you plan to cut new threads. Also, I'm assuming you are not installing coil-overs! If my assumption is correct, do you plan to also lower the bottom spring perch since you plan to remove 2" of the strut? One additional note...this is an important structural part so have it welded by a certified welder or someone who really knows what they're doing....a strut failure wouldn't be much fun.

[johnc]

I wrote this up a while ago and it was a sticky, but now it seems to have vanished:

 

For Koni 8610 Inserts

 

FRONT

 

From the dished bottom center of the strut to the top lip the overall length should be between 12.875” and 12.938”. The perch height (assuming 10” tall springs) measured from the top of the spindle casting (opposite spindle) is 5.250” assuming a .250” thick spring perch. The strut tube is cut at 5” measured the same way as above. Approximately 2” is cut from the bottom of the top half of the strut tube but measure first to be sure of the exact length.

 

REAR

 

From the dished bottom center of the strut to the top lip the overall length should be between 14.938” and 15”. The perch height (assuming 10” tall springs) measured from the top of the hub casting (opposite hub) is 7.250” assuming a .250” thick spring perch. The strut tube is cut at 7” measured the same way as above. Approximately 2.250” is cut from the bottom of the top half of the strut tube but measure first to be sure of the exact length.

 

PROCESS

 

The Koni 8610 inserts are a very tight fit inside the strut tube. The inserts typically have an OD of 1.725 and the strut tubes typically have an ID of 1.730. All cuts must be precise and perpendicular to the strut tube centerline. Use a lathe or a tubing/pipe cutter. Bevel both cut edges at 45 to 60 degrees leaving a flat of .030 to .060 at the bottom of each bevel.

 

Physically remove all paint and chemically clean (with Acetone) 3” to either side of the weld area. The strut tubes must be clamped into a large piece of angle and a tube (simulating the insert) of 1.720 diameter and 18” in length should be inserted into the assembly to help ensure straightness.

 

Tack weld the assembly in at least 6 places making sure the inserted tube still slides in and out easily. After tack welding, alternate 1” beads back-stepping around the circumference. Make sure no weld bead extends inside the strut tube and frequently check to be sure the inserted tube moves easily. Be careful not to weld the inserted tube to the strut tube.

 

Slide the spring perch over the strut and tack weld it to the strut tube on the underside of the perch. This tack weld should be on the back of the strut with the top of the perch 5.250” from the top of the spindle casting on the fronts and 7.250” from the top of the hub casting for the rears.

 

Measure down from the top of the strut tube to 3 places on the top of the perch. Make sure the perch is perpendicular to the strut tube. Tap the perch into position with a hammer before adding 3 more tack welds. After tack welding, alternate 1” beads back-stepping around the circumference on the underside of the perch.

 

INSERT INSTALLATION

 

Try installing the inserts into each strut tube. They should slide all the way in with nothing more then a light push. Most likely they won’t. Using any or all of the following, clean out and open up the ID of the strut tube:

 

36 grit 1.750” diameter flap sander

36 grit 1.5” diameter drum sander

Christmas tree shaped carbide bit

1.735” diameter reamer

1.750” diameter wire wheel

 

You can also sand the paint off the Koni insert and you will probably have to slightly grid down the weld at the bottom of the insert.

 

When you can easily slide the insert into the strut all the way to the bottom, make two spacers for the rear struts that are 2.250" tall and 1.5" in diameter out of .125 wall steel or aluminum (6061 T6) tube. Drop in and center these in the bottom of the rear strut tubes and install the inserts. Measure to make sure the inserts sit at the correct height. You'll probably have to shave a bit off the spacers. Once the spacers are correct, pour a little synthetic oil into the tube, install the spacers and the inserts, tighten the gland nut down, and torque to spec.

[zlalomz]

Hi John, have you had any word on the compatibility of the 8610-1437RACE struts to the Z?

[johnc]

Not yet.

[Toysport]

Well, you don't want to remove the top portion of the strut, because you won't have any threads to screw the retaining nut back into...unless of course you plan to cut new threads. Also, I'm assuming you are not installing coil-overs! If my assumption is correct, do you plan to also lower the bottom spring perch since you plan to remove 2" of the strut? One additional note...this is an important structural part so have it welded by a certified welder or someone who really knows what they're doing....a strut failure wouldn't be much fun.

The plan is to install coilovers and section the struts 2". I will not remove the top portion of the strut but lower the bottom perch. Is this a good route?

[Toysport]

I wrote this up a while ago and it was a sticky, but now it seems to have vanished:

 

It's a good thing I saved a copy johnc....

[JMortensen]

Different cartridges require different sections. I want to say that my MR2 rears required 1 5/8", and my 240 fronts to go in the back got a full 2". The best thing to do is not cut until you have the struts in hand.

[Zhadman]

All I can ever find for the 240Z is the 86-1811 and 86-1812 shocks. Are the 8610's a special order item? I see the 8610-1436/1437 Race versions in the Koni catalog, but according to JohnC's reply to this post...

 

Hi John, have you had any word on the compatibility of the 8610-1437RACE struts to the Z?

 

... I think I'm barking up the wrong tree.

 

No wonder I couldn't find them:

 

Bound to happen. We've been lucky to have a reasonably priced race shock available to Z racers for a long time.

 

Koni's replacement for the 8610-1149 is the 8610-1437RACE. It will physically fit in the Z strut tubes although the body is about .10" taller' date=' the max length (at full rebound) is longer by .57" and the stroke is increased by .39". None of these changes are show stoppers and the increased stroke is a good thing. How much a strut is shorted for these shocks will be different then for the 1149s.

 

But, the big question is valving... We're tryning to get a shock dyno graph and, unfortunately, the lastest Koni Motorsports catalog omits it.[/quote']

[THUNDERZ]

John,

 

Do you think I go off from those measurements for the 8610-1437's by adjusting the numbers to the different insert length for the rear and 8" springs all around?

[johnc]

My post above is an old one before I got my hands on the 1437 and before Koni sent me the shock dyno. The 1437 and 1149 are essentially the same for our purposes.