365 GT4 2+2 Shock Rebuild

Good day All,

Part of my suspension refresh was to also refresh the shocks. At first I was simply going to replace the shock bushings and repaint the shock housings, but as I thought about it I decide it would be best to rebuild the shocks while they were out. Although there were no signs of the shocks leaking I simply felt that 45 years on the internal seals was simply too long of a time to not replace them. Secondly, if there were any shock issues later I would have to remove a lot of my suspension to get to them... so it just seem prudent to do it now.

The car uses Koni 82-1824 for the front and 82-1825 for the rear (the non leveling one). The rears can be purchased new for about $280 USD, but the fronts are NLA... so the fronts would have to be rebuilt. Mine are original they are date stamped (6-74) and so I would prefer to rebuild both in order to maintain originality with the car. I researched a few firms that will rebuild Koni shocks and the prices varied from around $200 to $650 per shock. Reviews on all the firms were mixed and so I researched the rebuild process myself:

https://www.ferrarichat.com/forum/threads/koni-shock-service.446542/

https://www.ferrarichat.com/forum/threads/can-koni-shocks-be-rebuilt.359277/#post-141283862

I also exchanged e-nails with those that did the rebuild (Peter here on F-Chat) and they shared their seal source and also encouraged me to give it go.... so this thread will document this process.

Cheers,

Sam

 

Good day All,

First up is a few pictures of what my shocks looked like when I started. I have since removed and power coated the springs and so the shocks are ready for disassembly.

The top pic is the front and bottom pic is the rear

Cheers,

Sam

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Good day All,

Having reviewed the Koni rebuild threads I knew that I would need to fabricate my own tools to disassemble the shock. The first was a clamp that I could use to hold the shock shaft without damage. My first attempt was quite successful and works really well. Here I used some scrap Aluminum bar (2" wide x 3" long x 0.5" thick) and drilled a 5/8" diameter hole in the centre (the shock shaft is 0.625" in diameter). I then drilled two holes on the side. Next I cut the bar in half leaving two pieces each with an approximately 1/2 circle with a radius of just under 0.3125". Now to use the clamp I simply used to bolts and nuts and clamp the shaft between them. Doing this provides excellent clamping force without damage to the shaft surface. I needed to use this clamp to remove the top shock mount, locking nut, bumper rubber, and rubber disk.

Two more tools are needed to remove the inner brass nut with two slots and also the outer nut that has pin holes (see picture). I experimented with a few tool ideas and decided to use a 3/4" black pipe I had and then cut away one end to create two teeth that would mate to the brass nut. I then attached clamping piers to the black pipe and with a bit of force the brass nut loosened.

The outer pin nut has holes that are just under 5mm in diameter. Looking in my parts bins I found two M5 bolts and so all I needed to do was fabricate a tool using these bolts. To do this I used some scrap metal bar (cold rolled steel... 3" wide x 0.125" thick) and drilled two holes (5/32) that were the same separation distance as the pin holes (1.750"). I then tapped these holes to accept the M5 bolts. I then milled the centre section of the bar between the two holes to allow the tool access the pin holes. This worked perfectly and the pin nut could easily be removed.

Below the pin nut is a rubber seal and it appeared to be holding the inner shock tube quite firmly, I used a dedicated pipe wrench and gently move it back and forth and the entire assembly could be remove. What I found was amazing in that there was a lot of debris and overall crud in and around the assembly and also accumulation on the bottom of the lower tube. After seeing this nasty gunk I suspect my shock was not working as it should, as these particles would no doubt be causing problems with the various oil orifices within the shock. Since the shock is sealed the nasty material is from the various rubber seals within the shock that has obviously degraded and broke down over time.

I am now cleaning the various bits and taking notes and so I will post more over the coming weeks.

Cheers,

Sam

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Good day au400i,

Thanks for your post and your pictures! Your suspension pieces look great! Interestingly, your parts have different plating finishes than others I have seen. It simply goes to show that there really appears no rhyme nor reason to the plating finishes that Ferrari went with. For the most part it tends to be variable. However, the finishes are consistent in that there is a yellow, clear, and black. I opted for consistency and symmetry between the front and the back suspensions... although I am deciding if I should plate the suspension cross rod a different color than the arms. I have seen both on restores cars and for some reason I am partial to a bit of "splash" in this area. I guess I will need to decide by tomorrow.

Cheers,

Sam

 

Good day,
Thanks for the pic, but I am confused as to how this is related to rebuilding of the 365 GT4 2+2 Shocks?
Cheers,
Sam

 

Good day All,

I am continuing to make progress on my shock rebuild project. I have removed the shock piston and have been examining and cleaning the various parts. I am sooooo glad that I decided to rebuild my shocks, as some of the oil passageways were completely block and over time the crud somewhat solidified. I have attached a few more pics of the plugged areas. To clean these passageways I first used a straightened paper clip to push out the debris. Then I matched up some drill bits of the same hold diameter and use the back end of the drill bit to "push" the debris out. In the cases where the crud was fully lodged I used the business end of the drill bit and rotated the bit with my fingers in order to dislodge the debris.

For the foot valve (this valve that is located at the bottom of the assembly) I lightly scraped as much debris I could and then will place the valve into an ultrasonic cleaner (thanks Peter her on Fchat for this suggestion) to get at some pieces that are hard to get to and/or in doing so damaged the encased spring washers. Since I am unsure of the metals used within the various assemblies I decided to use a very inert cleaning solution of dish soap and water. I do have other chemicals that are more aggressive that I could use, but I am concerned that these chemicals could remove the surface finishes that the various metals may have.

As for the seal pack... The Koni seal pack is really basic and is comprised of three flat rubber washers separated what looks to be phenolic washers. I am using the seals as recommended and used by Peter, as these will fit without issue and are designed much better, as they are used in industrial settings. The only seal that I have not yet found is used between the top of the shock and the other pin nut. This seal is square profile ring with a tapered lip. Looking at the Koni design I believe that this seal's function is simply to prevent the shock from leaking and so it is not overly critical. If I cannot find a similar seal I will simply find something very close and use it... or if this is not an option I can reused my old ones, as they are still usable.

Once I have everything cleaned, etc I will post more pics and provide a list of the parts I ended up using.

Cheers,

Sam

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Good day Jean-Michel,

You are most welcome! I ordered the new seals and so these should arrive by the end of the week. However, I have some work items I have to deal with and so the parts will arrive before I can use them.

The upper seal is still unknown, but I did order a few others to see how well they will work. As I said I could reuse my old ones if needed. However, I have another plan that I am working on. What I may do is create a 3-d printed mold and recreate the upper seal. The mold would be pretty easy for me to do (10 minutes to CAD it up) and I have the necessary gear on hand (rubber chemicals, evacuation chamber to remove air bubbles, etc). I just need to confirm that the rubber mixtures I have on hand are compatible with hydraulic fluid. If so I may simply make my own upper seals. I will wait and see if the test seals I ordered will work appropriately and if so I will just go with them.

Cheers,

Sam

 

Good day Arvid,

You are most welcome!

Indeed I do have some pictures and where it is located. The seal sits between the outer pin nut and the internal seal pack housing. The attached pictures shows where it clearly. The outer diameter is approximately 2.125", an inner diameter of 1.75", and a thickness of 0.188".

Cheers,

Sam

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Good day Arvid,

It is possible, although the taper looks too precise to have been made by age related compression. Also, age related compression would cause portions not in contact with the ring nut to "bulge", etc and I am not seeing this. That being said the "test" seals I ordered are going to see if a standard seal will work appropriately and I will certainly post my results.

Cheers,

Sam

 

Good day Rick,

It is good to have you back!

I have not checked with them to see if they will supply the seal.... in fact I just sent them an e-mail. I will report back with what they say.

Thank you for the suggestion!

Cheers,

Sam

 

Good day Rick,

I have heard back from True Source and they are unable to assist:

Given the statement it implies to me that their relationship with Koni may not allow selling of any road going shock seals.

However, it was worth a try.

Cheers,

Sam

 

Good day Tim,

You are indeed fortunate to have a Koni specialist in the region. Where I am at there is really no one and so I pretty much would have had to pack everything up and ship it back and forth from the US. Although this does not sound like a big deal, it is... as each way one has to do a bunch of paperwork to ensure the importation taxes, etc are not charged and/or only charged on the repair, etc. Secondly, there is always a risk that shipped items can become lost or damaged. Thankfully this does not happen too often, but it does and can be a lot of work to get sorted. A number of years ago I shipped a wooden crate to the US and the City before the destination City the shipment mysteriously "lost" 100 lbs in weight ??? Ultimately a plastic shopping bag with a few parts was delivered... The shipping company's insurance department (Fed Ex Ground) tried for months to not pay the claim and at one paint blamed me for the issue! Thankfully I documented everything with pictures, etc and it basically took an issuance of legal papers before they paid out... and even then I never received an apology or an explanation as to what happened to the shipment or even the crate. Now, I really think carefully if I ship items and especially ones that are NLA.

Anyway... That you would be great if you can find out their contact info, as it would be most appreciated!

Cheers,

Sam

 

Good day Tim,

Excellent, thank you! I just sent them a message and I will report back with what they say.

Cheers,

Sam

 

Good day Oliver,

This is also great news! I just sent them an e-mail and I will report back with any news.

Thank you for the info!

Cheers,

Sam

 

Good day All,

This is just an update on the suggestion that Oliver made. I sent off an e-mail to FerrParts and Russ replied promptly this morning. They do not have the shock seals, but directed me to a shop called Performance Shock (707-938-5664) that are the Koni specialists in there area. I contacted them and spoke with Bruce, who was the right person to talk to about the seals. As I expected the Koni rebuild centres are contractually limited by Koni to not sell any of the road going Koni parts outside of their authorized centres. I fully understand their position and would agree with this for their specialty internal parts... but seals?... I find that this makes no sense, as it does not prevent anyone from finding or making the seals. In fact if one was so inclined, one could have the seals custom made for modest upfront $$$. If I had more cars, etc I would go this route, but for 4 or perhaps 10 shocks (365 and BB) I would have a lot of extra seals ... However, it is what it is and so I will simply continue on my path and will report up what I end up doing. Speaking of which, I received the seals recommended to me by Peter and they look good. I will measure and test fit them to be sure. Sadly, the other seals I ordered for the upper outer pin nut will not work. One of these might work, but it would rely on too much seal "squish" for it to do its job. Now that I can see how these seals fit and issues surrounding their use, I can now tailor my search using slightly different sizing parameters.

Cheers,

Sam