I realize this has been beaten to death and back and I've searched the search. I'm still unclear on a supplier and part number for a set of rear springs. Could someone please point me in the right direction for a set of rear springs that is known to work? I have a lathe. I can make spacers or whatever.

Here is the copy and paste I sent to your PM box.

I just got home from work. Weekends are toast for me now.
Here is a link to springs I think work but I have not bought any from Eibach.
My brothers machine has aftermarket springs that were on the machine when I bought it years ago. I estimate they are 170 lbs. My brother and I are both 135 lbs and these springs seems fine for us. You are a bit fluffier than us but I think you are going to have to buy a few sets before you are happy. I don't know what spring rate you should run but I know for sure the stock spring rate (223 lbs ) is way to stiff. So you are looking at between 170 - 200 lbs. The ID of the stock springs are 46mm or 1.81". The Eibach springs I am posting here are 1.88" ID so they are good. The stock springs are 11 5/8" long and the Eibach springs are 10" Long. So you will have to make a spacer.
Here is the Eibach link: https://www.kartek.com/parts-categories ... -tall.html

Thanks CO! The link works on the PM but something is wrong with it in your post. I'll report it here. Those springs look like just the ticket. I can turn some UHMW or Delrin to make a spacer.

Eibach 1.88" inside diameter springs. 10" length.

https://www.kartek.com/parts-categories/eibach-springs-with-188-id-10-tall.html

I think I'm going to vote for 185lbs to start. You know, since I'm fluffy. lol... I found them at Summit Racing for $60 each with free shipping.

https://www.summitracing.com/parts/eib-10001880185

They're even red powdercoated.

I might be able help you with the spacer issue.
What I did on my machines was cut my old stock springs to the length I needed.
I used a torch to cut them and to also level the bit of the spring sticking in the air. It took some trial and error but it was good enough for me. I also cut some UHMW spacers on the lathe because I wanted more preload and didn't want to F around with the torch some more.
Either way works but once you cut the stock springs you can't put them back on if you sell your machine.

I can get 12" of 2.5" UHMW rod for $20 delivered on Ebay. Probably just do that and turn them on the lathe rather than cutting the stock springs.

https://www.ebay.com/itm/2-5-Diameter-UHMW-Polyethylene-Plastic-Rod-Price-Per-Foot-Cut-to-Size/282395333687

One final comment tonight before I log off.

When you get these springs and have finalized everything, please return here and post ALL relevant info so that other people can use it. I really hate it when someone don't post end results. It don't happen very often but it does happen. It's annoying.

Info needed to complete this thread:
Final spring rate, weight, spacer dimensions, ride report.

Thx in advance
CO

Will do. I'll take plenty of pics and post the results. It was frustrating to see a number of posts where people were talking about doing this or had done it but no specific information. Made researching it no fun. I'll make sure this thread documents what was done.

Are the Ody & Pilot rear springs the same size? Looking at a Pilot photo they look to be longer than 11 5/8".

I was just looking to see if there were any Ohlins that would be suitable but their website isn't that great for info. I don't mind emailing them for you. I know they have distributors in America but don't know how well known they are over there. Here in Europe they are very highly rated.

Ohlins are great shocks but not very common anymore.
When I was racing some guys had them on their race car.
I believe the Pilot shocks are longer.

Got the springs and the stick of 2 1/2" round UHMW and I had a bit of time off this afternoon so I took advantage and put in some work on the rear spring project.





The new 185# springs are exactly 1 5/8" shorter than the originals.





Making the spacers was a pretty simple deal I cut the UHMW on my band saw to 1 3/4" pieces and chucked them up in the lathe. I used a 1 3/4" hole saw to remove the necessary material. Worked fine even though the hole saw is not deep enough so I had to flip the pieces and drill from each end. I faced the pieces to length and to smooth out the ends.



Assembly is straight forward. I used the Tusk spring compressors which work perfectly for these springs.





Hopefully these will work as good as they look. My FL350 is still in pieces at the powder coat and machine shops so it'll be a little while before I can test and report back.

Does the spring have any tension on it as it set's ?
By chance did you log the amount of change in lenght with each click on the pre load adjuster.
If no preload on spring the way it sets now, you are at zero preload on the shock.
Then we can follow as you set up the off or add pre load.
That of course if we know how much of a lenght Change there is for every twist in the pre load adjuster based off of 185 per inch.
Do we know the old spring free lenght compared to the installed lenght with the adjuster at zero or one. Can we assume the old spring rate was? (223).
With this info one can log change and effect according to the new rate.

Thanks for info.

adnoh the original spring rate was actually measured by me a few days ago.
Here is the thread: viewtopic.php?f=1&t=18465
It is NOT 223 like we all thought. It is actually 210.

No offence Terry but I don't like what you did there.
The spacer should have a step or pocket cut in it so the spring can't slide around.
Right now you are relying on the shock sleeve to do this job. Those sleeves are very brittle now after all these years.
Does look pretty though.
Just my opinion.

There is preload on the spring now with the adjuster at the lowest setting. The spring is compressed exactly 1/2".

We'll see how it goes.

As they sit right now spring heights are as follows for the preload adjuster notches.

Position 1 = 9 1/2"

Position 2 = 9 7/16"

Position 3 = 9 3/8"

Position 4 = 9 1/4"

Position 5 = 9 1/8"

Thank you, I will work up some numbers for you. I will use a speed sheet for you to down load and use.
I will need some more info. If your willing to provide I'm pretty sure you and others will find it helpful. The whole board can add what they know to help.
Adnoh
I will start my review and logging process. I need some fun since it's cold out side.

Did some quick math.
Your new set up: shock pre load 92.50
Old set up: 78.75
Some one check please!
I will now do some adjuster numbers based off this info
New spring 185
Old spring 210
I used these numbers to get above pre load on shock
Thanks

more quick math
please check math

Now I need shaft length for bottom out poundage.
Also need ratio between shaft travel and wheel travel. The shaft will move less per inch of wheel travel. This shock does not operate at a 1 to 1

Here is a few pics why i need the numbers.

You can see from the numbers that the way the spring is set for that shock will have a impact on handling.
The % and bottom out as well as others will effect the traction forces available. Once i have the rate per inch I will have more to say on available traction. Cand ody can elaborate on this as he was a driver. For a quick example would be spring rate effect on rebound damping and load at a given point on the tire. This will change the the way the car carries through the corner based on available traction on that tire and the adding or removal of weight from the other tires. Basically the change from over to under steer. Hope I said that right, cand ody can verify.

Adnoh

Thanks for the calculations adnoh. It'll be a while before I can provide the required information. I need and actual complete vehicle to put them on. lol...

Hope to have everything back from the powder coaters and the machine shop next week so I can begin reassembly.

adnoh I can get you the wheel/shaft ratio next week and I will post it here for you. It sounds like a fun in the shop project for me on Monday or Tuesday. I'll post that for you here. I am interested in these numbers for my self. Just for fun when I post this can you also do a sheet for the 135lbs/in springs we have on our machines ??

Should be an interesting study since I weigh as much as CO and his brother combined. lol...