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Discussion Starter · #1 ·
Hi,
I have recently bought a mk1 with P5 sport drives. Was dead impressed by the ride compared to standard. On removing wheels it turns out a lower bush has come out. Happy to take that on with a custom job. Sadly the schrader valves are damaged so probs no nitrogen.
They are off the car so makes me think I should attempt to rebuild them, much more eco than scrapping and buying Meisters. With that in mind and knowing they are long discontinued, has anyone else taken this task on for these P5?
If I could get info on the following I would be confident to have a go, assuming shims are all ok..
1. Oil grade and quantity
2. Seal / o ring spec and dimensions
3. Nitrogen pressure
4. Anything else - like advice to walk away!
Thanks in advance
Dan
 

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The P5 Puredrives were Protechs, the Sportdrives were built in house by P5 with their own parts. I have a set that needed rebuilding, and couldn't find anyone to do it, certainly not Protech. Phil shut up shop years ago and isn't contactable anymore. I ended up getting a new set of Ohlins DFV. I still have the P5s though, one of the front ones is in a sorry state of disassembly, the others are intact. You're welcome to have them for free if it would help you out. I'm in Bristol, send me a message if you want them.
 

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Discussion Starter · #4 ·
Thanks very much for the responses.
mine should be ok but I will be freestyling it with regard to oil grade and nitrogen pressure. I have family in Bristol so depending on how my year down goes I may be in touch!
I think with oil I will look at what comes out and try to compare with 5w and 10w with my home rheometer (stick stirring The oil in a cup) and make the decision on that basis. As they are Uk built I will assume I can get new seals and rings. The springs are looking flaky so will get them blasted and then re coated whilst they are off, assuming I don’t ruin anything in the process and have to get on the phone to meister r or gaz!
 

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Discussion Starter · #5 ·
As an update the dissemble was going pretty well. Until I realised I had damaged shims probably using the Main piston to remove the floating piston. Think shims aren’t too easy to match. I did get the pressure and volume of oil if not the viscosity. Will be in touch, low ender!
 

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My SportDrives are knackered too. Would love to get them rebuilt but will probably have to put Meisters on instead.
I remember a couple of years ago one of the WIM techs damaged the valve, it's just a bog standard schraeder, I was also lucky enough that Phil answered my call and told be the nitrogen pressure was around 70PSI.
Not sure if I dare try calling Phil again, he definitely didn't seem interested in shocks anymore.
 

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Discussion Starter · #7 ·
I’ve bought some meisters, but I have a batch of spare presta valves for the P5. I’ve removed all seals from one shock to take to a bearings and seals shop. The shafts are in pretty good nick.
The only” issue now is grade of oil, somehow replicating shims, and putting them all together again.
I got in touch with Ian Gardiner a while back who could have a go for £100 a shock not until May, I just bought meisters but he ventured that the oil in p5 is most likely 5 wt, but also advised that the P5 look very unusual from the inside (only one shim on each piston) and basically advised me to put them in the bin.
lowender above is in Bristol and has kindly pledged his P5 shocks to me - that could get somebody to a point where they have shims. I was going to have a family member pick up lowenders shocks but that hasn’t happened yet. My shocks and springs etc are in kit form boxes up nicely plus homemade lower bushes, and I would
Happily donate them to somebody if it helped get one set of shocks up and going. Realistically mine will only go to the dump now as I have too many other projects!
 

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As Phil's partner in crime I should have (Somewhere on various Dropboxes) a full set of the original engineering models (Solidworks) and manufacturing drawings for the various bits. I'm sure if I could find the time, I could probably run back through my e-mails to see who the suppliers of the various seals etc. Some were custom rather than off-the-shelf, so getting those made might be a little more challenging. All the parts were made by a single CNC shop (and a lovely job they did too) somewhere around Humberside so there's nothing clever in the design that would need 5-axis etc. machining.
 

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Discussion Starter · #9 ·
As Phil's partner in crime I should have (Somewhere on various Dropboxes) a full set of the original engineering models (Solidworks) and manufacturing drawings for the various bits. I'm sure if I could find the time, I could probably run back through my e-mails to see who the suppliers of the various seals etc. Some were custom rather than off-the-shelf, so getting those made might be a little more challenging. All the parts were made by a single CNC shop (and a lovely job they did too) somewhere around Humberside so there's nothing clever in the design that would need 5-axis etc. machining.
Hi Dave thanks for responding, I can see .step models in rhino so that could be very helpful. As would be drawings that have details / notes etc if that’s not in solidworks native format. As would the grade of oil used. It would be great to make at least one more working set from the several that are knocking about in miscellaneous states of repair! Cheers
Dan
 

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We were using SIlkolene Pro RSF. It's all been subsumed into a different range, but the 5W should see you right. I wouldn't use anything but the Silkolene as it's rather good at damping down certain behaviours.

Rather than creating a load of STEP files, I'll probably import everything into Fusion360 and link you from there.
 

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I've been looking through the drawings and there are some iterations in the design as well, so what you've got may be from one of two particular iterations. The only bespoke seal in the was the PTFE band that provided the main low friction seal around the piston. Everything else was off-the-shelf. Whether they're still off-the-shelf is another matter, but the myriad O-rings (I think there are two on the plastic floating piston separating gas from fluid and another two energising the PTFE band) are all BS items. We had an energised seal at the top of the damper then a Trelleborg quad sealing ring below that.

Whereabouts are you? If you're sufficiently local, I'll try and pop round when you're pulling one apart. I may even be able to say what needs replacing. Just hope it's not a piston rod because the chrome shaft is expensive (and normally they only like to sell you 6m or so). It's more likely to be the PTFE band.
 

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Discussion Starter · #12 ·
Hi Dave thanks for this - I’m in Southampton and I think another member is in Bristol. Ive already dissembled all of mine and damaged the (single!) shim on 3 of them in the process hence I’ve got some meisters now but I would rather sort these out than get rid, given that for the most part it’s all in good nick and when working it was all good.

One of my shafts has a little pit in it but nothing serious I don’t think.
 

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I had a chat with Nitron today. Apparently one of their guys is looking into a more road/fast road based set for the MX5. Mainly due to pressure from the states but I think if we can all chime in they will really push forward with them. I've emailed the chap developing them and said that the SportDrives were one of the best and that I could possibly pass on the design specs and even a spare set if necessary. Also that my car could be a test subject (in the hope of a massive discount 😎)
Would anyone else be interested in a set ?
 

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I would have an interest and would welcome a private conversation on spring rates, commonality and adjustability, and what they consider acceptable for ''road /. fast road spec'' on bumpy Ultser tarmac.. even SEB / Citroen had probs...w
 

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If Nitron are as good as they say they are, they won't need to rip off Phil and Dave's IP.
No comment.... However, our method of damping would be somewhat different to Nitrons. Unless they've changed recently, their piston is a typical shimmed variety and ours err... isn't (Think of it being somewhere between a shim damper and a DSSV). They may not want to go down our route anyway. Dodgy theory states that all you need is the damper curve to reproduce the effect. Actual wisdom (and a few SAE papers on the subject) have shown that two dampers with same curves behave very differently.

FWIW I'm working with Dan getting all the drawings and models across for the Sportdrive. I've located the backups - just need to do some sorting out and getting what the final fiddled-with settings were from an e-mail/SMS trail dating back over 10 years.

And yes, just say no to ripping off IP. I still work in an IP business and you should what a bastard of a NDA I make my clients sign. It's so bad that they're not even allowed to mention that they're under a NDA.
 

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If Nitron are as good as they say they are, they won't need to rip off Phil and Dave's IP.
Not saying they rip off Phil and Daves work but basically look at how the SportDrives achieved what was required and see if they can match or even possibly improve the result going down their own route.
 

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Or, in other words, rip off the IP. If I were still in the business then I'd get incredibly miffed with the idea of a competitor taking my pride and joy apart to learn the secrets in order to clone it. Generally speaking, the courts do too.
 

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Sorry if I've upset you there Dave, they wouldn't be cloning your SportDrive design at all. Rather using their own for softer springs and tweaking the valving to suit. I was thinking more about the dimensions and stroke travel. After chatting to their engineer today they seem really keen to offer a more road going set up.
Early days yet.
 
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