74 1.8L rear coil spring color dots Options

[L-Jet914]

I am swapping out my original rear coil springs for new 100lb springs from 914 rubber. I was reading through the factory service manual and found out that my springs are from the Group 2 and Group 3 stiffness via the 2 and 3 green dots on the coil. The service manual states there are 3 different stiffness options. I wonder if all the 74 1.8s came with this spring option or if it varied. Per the service manual it says they were suppossed to be matched in pairs but from the factory I have no idea haha. @starbear @wonkipop

[wonkipop]

@L-Jet914

i dug out the old boge rear shock i took off a few years back.
to the spring ledge from c/l of lower shock connection joint is 185mm.




i re-measured the billy on the car and the same measurement is 190mm.
the perch ledges seem to be around 15mm intervals.
with the standard factory springs it means the boge perch is half way between two billy adjustable perch rings.
we went for the higher one (5mm more than the boge) because we felt the original springs were half a century old so maybe ok to compensate for loss of tension, sag.
it seemed to work for us.

but new 100lb springs would throw all of that right out the door.

the car currently sits an even 190mm above the ground if i measure to the bottom of that little seam that is where the floor pan joins the sill panels, back in further than the bottom of the external sill covers.
and if recall correctly there is a dimension given for minimum clearance in our glovebox owners manuals - if you look closely that min dim is p[orbably/likely to the bottom of the flexible flaps in front of the engine bay on the floor pan? the dim is 130mm. no way was the car ever originally that low to the floor pan generally so the 130 must be to those flaps which are the only thing that hang down seriously low. from memory i have 135mm there so i am probably maybe 5mm higher than stock mins. which kind of fits with the billy setting v the old stock boge. i think there was some other measurements we found in factory workshop manual which let us know we were in the range of stock but high end of range. big difference being its not set up nose high anymore.

[L-Jet914]

@L-Jet914

i dug out the old boge rear shock i took off a few years back.
to the spring ledge from c/l of lower shock connection joint is 185mm.




i re-measured the billy on the car and the same measurement is 190mm.
the perch ledges seem to be around 15mm intervals.
with the standard factory springs it means the boge perch is half way between two billy adjustable perch rings.
we went for the higher one (5mm more than the boge) because we felt the original springs were half a century old so maybe ok to compensate for loss of tension, sag.
it seemed to work for us.

but new 100lb springs would throw all of that right out the door.

the car currently sits an even 190mm above the ground if i measure to the bottom of that little seam that is where the floor pan joins the sill panels, back in further than the bottom of the external sill covers.
and if recall correctly there is a dimension given for minimum clearance in our glovebox owners manuals - if you look closely that min dim is p[orbably/likely to the bottom of the flexible flaps in front of the engine bay on the floor pan? the dim is 130mm. no way was the car ever originally that low to the floor pan generally so the 130 must be to those flaps which are the only thing that hang down seriously low. from memory i have 135mm there so i am probably maybe 5mm higher than stock mins. which kind of fits with the billy setting v the old stock boge. i think there was some other measurements we found in factory workshop manual which let us know we were in the range of stock but high end of range. big difference being its not set up nose high anymore.

Thank you for supplying the measurement from the middle of the bottom shock bolt hole to the bottom of the original perch. I may move the snap ring up one notch and see how it does because on the 4th up from the bottom the new 100lb springs are not under tension when installing the top hat until the top hat starts pushing the spring down when tightening that special through nut that holds bottom mount bushing in place. I am so used to replacing struts/shocks with wall mounted spring compressors to reinstall the top hat piece that I was concerned at how easy it was to install top hat on the new Bilstein rear shock with the coil spring without the need to compress the springs. I may be in the states, but have come to welcome the metric system in measuring lengths/sizes of bolts/sockets etc as I see it to be more accurate in some aspects. Especially in my job when I install door guard accessories on vehicles, I mark everything out in millimeters so it's mark once done haha. I fault myself for not enjoying to read fractions on a tape measure haha especially when the instructions give a measurement in decimals for the SAE side. I purchased tape measure that has both metric and sae and for the most part use the metric side these days.