Sectioned struts not matching any measurements from JohnC, want to go from illuminas to koni 8610s

[BluDestiny]

So I bought my 240z with sectioned struts, tokico illumina struts and hyperco springs. My driver front was leaking so I decided to take some time this weekend and see what I actually have. My fronts are Tokico BZ3099, the common 87-89 MR2 rear struts, and my rears are Tokico BZ3015, which are 240z front strut inserts used in the rear. Since tokico is no longer available I'm thinking of just going with koni 8610's since this is mostly a track driven car at this point. The problem is in the measurements.

 

Below is an except from the strut sectioning sticky by John Coffey

 

Quote

SECTIONING DATSUN 240Z STRUTS

 

For Koni 8610-1437RACE Inserts

 

General

 

Remove stock lower spring perch from all the struts and remove the brake line brackets from the front struts. Use a cutoff wheel to remove all the spring perches and brackets above the welds and then grind the welds off the strut tube. Get it smooth but be careful not to grind off too much of the tube itself and thin it.

 

Front

From the dished bottom center of the strut to the top lip the overall length should be between 12.875" and 12.938", measured from the inside using a tape measure. The threaded collar weld-on ring height (assuming 10" tall springs and 5" tall threaded collars) measured from the top of the spindle casting (opposite spindle) is 5.250". The strut tube is cut at about 6.5" up from the top of the spindle casting to put the welded section under the threaded collar. From 1 to 2" is cut from the bottom of the top half of the strut tube but you must measure first to be sure of the exact length as specified above. The most important measurement is the overall length of the strut tube (12.875" to 12.938").

 

Rear

From the dished bottom center of the strut to the top lip the overall length should be between 14.938" and 15", measured from the inside using a tape measure. The threaded collar weld-on ring height (assuming 10" tall springs and 5" tall threaded collars) measured from the top of the hub casting (opposite hub) is 7.250". The strut tube is cut at 8.5" up from the top of the spindle casting to put the welded section under the threaded collar. From 1 to 2" is cut from the bottom of the top half of the strut tube but measure first to be sure of the exact length as specified above. The most important measurement is the overall length of the strut tube (14.938" to 15").

 

Tokico Ilumina BZ3099 and BZ3015 Inserts

 

General

Basically all the steps are the same except for the measurements and the tightness of fit of the Tokico inserts in the 240Z strut tubes. The Tokicos are a little smaller OD then the Konis and slide in easy.

 

Front

From the dished bottom center of the strut to the top lip the overall length should be between 13.375" and 13.500", measured from the inside using a tape measure. The perch height (assuming 10" tall springs and 5" tall threaded collars) measured from the top of the spindle casting (opposite spindle) is 5.250". The strut tube is cut at about 6.5" up from the top of the spindle casting to put the welded section under the threaded collar. From 1 to 2" is cut from the bottom of the top half of the strut tube but you must measure first to be sure of the exact length as specified above. The most important measurement is the overall length of the strut tube (13.375" to 13.500").

 

Rear

From the dished bottom center of the strut to the top lip the overall length should be between 14.938" and 15", measured from the inside using a tape measure. The perch height (assuming 10" tall springs and 5" tall threaded collars) measured from the top of the hub casting (opposite hub) is 7.250". The strut tube is cut at 8.5" up from the top of the spindle casting to put the welded section under the threaded collar. From 1 to 2" is cut from the bottom of the top half of the strut tube but you must measure first to be sure of the exact length as specified above. The most important measurement is the overall length of the strut tube (14.938" to 15").

 

The rest of the process is that same as for the Koni inserts and Tokico includes the gland nut for their shocks. They are hex shaped so a large adjustable wrench (or gland packing nut wrench) is needed for installation.

 

So in the front, the koni's require about 0.55" less length than the illuminas, and the rears are the same. Koni's need to have an overall length of approx 12.9" and illumias need a total length of 13.5. The rears are the same for illuminas and konis at 15"

 

The problem I have is my measurements are a little off. My rear overall tube length is 15.25" with the perch at 9.5" from the bottom of the tube, and my front tube is 14" with the pearch at 8.375". My rear spring is a 10" 250lb hyperco spring, and the front is a 9" 225lb spring, both on 5" sleeves. 

 

I have not fully removed the insert, just enough to see the part number. I have to assume there is a spacer at the bottom of each to fill the space and bring the strut insert to the gland nut. I want to drop in the Koni 8610-1437RACE inserts and increase my springs to 325f/350r rates using 10" springs as listed in the faq. 

 

Does that sound feasable or will I need to section my struts again to get the proper length?

[AydinZ71]

The rear strut tubes require a 2” spacer to be placed inside the tube. Then the finished height of the tube is however tall it needs to be for the cartridge to slide in and the hand nut to secure the Insert. First time around I didn’t realize I needed a spacer, so I had to go back and add material. The fronts don’t need the spacer, so it’s just however long they need to be for the hand nut to work. 
 

i believe the distance from the cast portion of the strut (bottom of the tube) to the bottom of the spring landing was 7” in the rear, and 5” in the front. 

[BluDestiny]

So what you're saying is what matters is if the spacer is there to make up the distance to the gland nut. I can then leave the tubes themselves the same and make sure the insert itself comes right up to the gland nut. I am artifically raising the car by however much that spacer length is in the tubes.

 

Then I can play with whatver length springs I need to really get it centered.

 

Or are you saying the spacer is needed because of how the tube is centered and welded to the cast portion? 

Edited November 8, 2022 by BluDestiny

[AydinZ71]

Nah the spacer is there to give you the strut travel you need. it lowers the hub to a level where you have sufficient droop. If the strut travel is too short, you will lose contact patch with the pavement on your inside tire when taking tight turns. Without the spacer, your control arms will be completely horizontal, with zero droop. Basically, when you lift the car you will wonder “huh… why doesn’t the suspension drop”. 

 

But yes, with the spacer in there you just need the tube to terminate with enough length to get that gland nut in. Make sure you estimate it well so you get several engaged threads before it makes contact, and not so little that the nut bottoms out before making contact with the insert. I made a silicone gasket on top of my insert to cushion when tightening the gland nut on, but that’s optional. 
 

Where your lower spring perch goes is entirely dependent on your length of spring. Mine are 10”, but if yours are different you will need to figure out your own perch height. 

[BluDestiny]

I already have perches welded on. The owner who did this must have kept it longer than normal for the suspension travel, which means I just have to use spacers to keep the articulation points the same. So that helps a lot. I just need to get the spacers and inserts to match the tube length and I should be good. 

[AydinZ71]

Good luck! And just to be specific, those 2” spacers placed in the bottom of the rear tube are for the 1437RACE model of the Koni’s specifically. Just wanted to be clear. You do not need them in the front.