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Hi M5Board — hope everyone is weathering the COVID storm in good health and socially distant drives in your M5s.

In a bit of a pickle and wondering if anyone has been down this road before. I have a 2000 M5 with a Dinan S2 package and a blown rear strut. Last month, when I replaced the rears with new Koni yellows, I noticed that the previous setup was with "Dinan by JRZ" struts, not Konis. Since Dinan currently sells nothing but Konis I assumed the yellows I installed would do the trick.

Here's where it gets interesting. The ride is much improved — smooth, no creaks, no harsh impacts, but the cornering is a mess. On entrance ramps and sweepers, the rear is bouncy, like I'm hitting the bump stops as the weight transfers. It's scary at highway speeds, and the car was never like this before.

Last week, I sent the JRZ struts to a JRZ approved shop to get them rebuilt...but they can't repair them as they're "Dinan" not JRZ. So I called Dinan to see what to do, and Andrew in service said that he didn't know if Koni offered a warranty on JRZ parts (can't imagine why they would), and then hung up on me. Super.

So here I am asking two questions:

1. Has anyone successfully rebuilt their Dinan by JRZ struts before?
2. If not, has anyone gone from JRZ to Koni and nailed the settings? 1.25 turns is just not cutting it on the Yellows.

Appreciate you reading this far.

938680

The strut in question ^

938679

😍^
 

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I have the JRZ shocks as well and they are sublime. Rides MUCH better than stock and still handles better. It's JRZ shock that is custom valved for Dinan.
But, they had a nasty habit of starting to clunk if you drove your car in cold weather (as in close to freezing), and the clunking remained even as it got warmer (i.e. once they started to clunk, it stuck). Hence they had a lot of warranty issues early on. I had 3 out of 4 shocks rebuilt for free (back in 2007/8)
I did actually ask Steve Dinan about this back in 2012 or so when he was presenting at a local BMW CCA event. He then also stated that they redesigned the piston to have a slightly longer sleeve (if I recall correctly).
Since then I have had one more shock go bad (also started clunking), and had it rebuilt in 2013. Cost was $250.
However, in 2015 Steve sold his business and the new Dinan has nothing to do with him or his prior cars (as far as I understand). He did later start a new company - CarBahn. may be worth calling there and see if they can help?
Very interested to see what you find. I have only driven the car 10k miles since 2013 (and never in cold weather) so shocks have lasted me well now.
 

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E-mail Tim @Olsen Motorsports they rebuild JRZ stuff and may be able to help.
I replaced my "Dinan Konis" with another set of new Koni yellows, same Dinan blue springs.
They are great FWIW, not sure if there was any actual revalving, or just a rebranding/label.
 

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Discussion Starter #4
E-mail Tim @Olsen Motorsports they rebuild JRZ stuff and may be able to help.
I replaced my "Dinan Konis" with another set of new Koni yellows, same Dinan blue springs.
They are great FWIW, not sure if there was any actual revalving, or just a rebranding/label.
We're on the same page @KRAM5 — Tim has them at the moment and just sent a note that he's contacting JRZ to see if they know who is fixing them these days. Thanks for the reply and I may go with your setup as I'm sure the car is still excellent with a full Koni setup.

@155plus Thanks for the reply and that's super interesting. The car lived in CA all of its life before coming to Michigan. The struts both started to go in October, so the cold weather clunk might be to blame. Good thought on CarBahn, I'll give them a call as well. I'll keep this thread up to date on my findings!
 

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bpb3 - please post your findings. I had JRZs on both of my S2s and had the same problem with the fronts on one of my cars. A few years ago, I sent them to Dinan to be rebuilt but Dinan said they never received them so I had to replace them with yellow Konis. I didn't like the Konis on track and eventually one of them failed so now I'm trying Bilsteins.

Within the last few months the front JRZs on my other car have failed so once again I'm in need of having JRZ struts rebuilt. Sadly the JRZs on the second car have driven less than 7k miles (although they are 15 years old).

I still have the rear JRZ shocks from my track car if you need to borrow them while yours are being rebuilt. PM me if so.
 

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At this point from your interactions with Olsen Motorsport you should just try and get as much technical information from JRZ (NL) and look for a non-JRZ affiliated re-builder. See if you already have the redesigned piston (piston-sleeve), or if you can get someone else to make the modification on your existing setup.

The Dinan JRZ suspension is definitely in the same league as the Dinan supercharger, the headers, the Dinan-wheels, and well worth the investment to continue the effort the rebuild them.

Based on Olsen Motorsport's comments I'd guess JRZ is not interest in supporting this legacy product, especially if there were known issues and they need to provide any sort of warranty with each rebuild.
 

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Update, and thanks to @JohnAnthony and @KRAM5 for the tips.

1. Tim Olsen heard from JRZ - they offered to rebuild them in Holland. Good to know they are still supporting the product.
2. Since shipping to and from Holland would take some time, Tim is sending them off to Chris Hagen at inertia lab for a rebuild. Good time to note that Tim was great to deal with during this and was super quick to respond to all questions. I'll keep you all posted on updates from Chris as I have them.
3. Also want to thank Erin at CarBahn who was very helpful when I called to ask if they had any tips. It sounds like the team there is made up of Dinan OGs, thanks again for the tip @155plus.

Considering this is a 20-year-old car with specific aftermarket enhancements, it's surreal that we have this level of support and community engagement for our M5s. Feels almost as good as the cars themselves. Almost...

More soon.
 

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Interesting thread. I can't speak about the JRZ's as I've never had any experience with them. Glad to hear you were able to get resolution on them. And also agree with you about the team at Carbahn - Erin and the crew there are great.

As far as the KONI Set up, I have had two M5's with that set - complete suspension with the DINAN Springs and never had that kind of experience with them that you mention. Both cars have/were driven aggressively and never had that issue. Did you adjust them prior to first installation? This is probably a silly question here, but did you set the spring perch at the right notch on the rear struts / shocks? If you ordered them for the M5, they should come preset for that car but there are three notches on that shock. Each notch will affect spring compression and setting.... sitting. I did not adjust my rears when I installed them and they have performed quite well for me - in both cars.

In the past, I actually spoke with a Koni Rep (Sorry, can't remember the name), back then he informed me that the KONI shocks you get off the shelf are different to the DINAN ones because Steve specified the damping rates and such for the ones DINAN carries.
 

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I may be partly to blame for the problem I had with my Konis. On the North Course at Pocono, you have to drive over a drainage ditch as you enter the infield. The more you cut the corner, the deeper the ditch. It is pretty hard on my heavy car but you know, when you've got another car in your sights or your buddy is on your bumper and you just HAVE to get away from him . . .

The Koni front strut is slightly necked down where it is squeezed by the pinch bolt. Mine wore at the taper and would slide down even when I clamped the pinch bolt shut. I'm pretty sure the repeated impact at Pocono wore it out. And really, the Dinan suspension is too soft for track use so that didn't help matters. Hence the switch to Bilsteins.

I'm hopeful I can get the JRZs rebuilt on my other car. They clack even when moving the car around in the driveway. It's embarrassing. And I'd like to be able to drive that car if I want to. I'm anxious to hear how this works out for bpb3.
 
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