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Thread: Is there a Dinan Strut Support for Z8?

  1. #1
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    Is there a Dinan Strut Support for Z8?

    Is there a strut support made by Dinan specific to the Z8, and if so, is it different or better than the BMW PP?
    Thanks in advance for any info on this!

  2. #2
    Dinan do make a Castor Plate that several of us have used, and also noted that using it prevented getting any dome distortions, as well as helping the handling. It simply fits below the shock tower dome, rather than sandwich it like the PP. I still have my Dinan Castor Plate, but now it is combined with my PP as the lower part of the PP's 'dome clamp'.

    However as of this time I don't think Dinan makes an actual strut-brace for the Z8.

    Sadly they also no longer have any stock left of their excellent adjustable swaybars, my single favorite and most recommended upgrade to the Z8.
    Andrew Macpherson

    Expert Z8 Inspections, with full support for both Z8 sale and purchases.

  3. #3
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    Steve Dinan has offered to try to come up with an alternative strut brace for the Z8. He believes the current PP brace is less than ideal, both functionally and cosmetically. Unfortunately, the engine compartment on the Z8 is very restrictive in terms of fitting a brace so it may turn out that the only option is a better looking unit. This project will be tackled this winter when my car is back for upgrades and I will report on his findings. He will also be working on a suspension upgrade for the Z8 and I will discuss the anti-roll bar situation with him. If Dinan cannot justify another run of their bars, perhaps we should contact one of the anti-roll bar manufacturers and try to put together a custom order. This would give us the opportunity to go with a hollow adjustable bar which would result in a weight savings.

  4. #4
    Z8 Ate My Homework! Norcal's Avatar
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    Glad to hear Dinan may work on a better suspension/chasis set up. As noted previously, the ACS set up I used to run is too harsh for CA roads, and the touring nature of the car. As for the bars, tubular adjuustable bars would be great. Not having bars available for the Z8 is a crime, as they are such a great improvement. A group buy, and a stock pile is in order.

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    It is important for you to know that the current plan for upgrading the suspension on my Z8 will not follow the lead of the Alpina set-up with its increased compliance. The roads where I live are relatively smooth and I want my Z8 to handle like a sports car, not a GT. To be clear, my car currently uses the AC Schnitzer springs and struts which are stiffer than OE and lower the car app. 1 inch. Dinan thinks the front springs are too soft and wants to go stiffer! He has already installed custom camber/caster plates up front which not only increase positive caster but also increase camber to a total of 1.5 degrees negative. This allowed the use of 265/35 ZR19 Yokohama Advan Sport tires in front and we're using 285/35 ZR19 in the rear. Dinan also adapted monoballs to replace the compliant bushings in the front tension compression rods. These changes have resulted in a much more responsive handling package and I am thrilled with the results. Narrowing the spread between front and rear tire widths along with the increase in negative camber have given the front end much more grip and the monoballs have significantly increased steering response and accuracy. I was a little dubious about the switch to the Yokohamas (Dinan's recommendation) since they aren't particularly sticky tires but I must say I have become a believer. Unlike the PS2s, they have very stiff sidewalls which improves steering response plus they are incredibly stable at high speeds. They also put power to the road better which has become quite an issue with the new motor and 3.91 gears. Steve said he thinks he could fit 275s up front if he increased negative camber to 2 degrees and 295s in the rear with no problem but I'm a little reluctant to run 2 degrees negative on the street so the current set-up may be the best compromise. Dinan also feels the steering rack on the Z8 is too slow and would like to adapt a quicker one onto the car but I'm not convinced this is necessary since the current tweaked set-up feels ideal to me. Knowing Steve, he will have other ideas to explore when he gets his hands on the car again, so there may be some surprises in store. For what it's worth, we discussed going to a coil-over set-up, but Steve is not a big fan for street use (pounding around the 'ring is another thing altogether), citing a number of issues related to suspension geometry. We also discussed replacing other compliant bushings in the suspension with harder compounds or spherical ball joints, but Steve said the compliance is an integral part of the suspension's design and removing it would destroy the car's handling, not improve it. The only place he thinks it helps is on the front tension compression rods since compliance there does not contribute to better geometry. I thought that change might result in an increase in road imperfection feedback into the car but was pleasantly surprised to discover this was not the case. I was also a little concerned about going to the 3.91 gears but it turns out that, with an 8000 rpm redline and the 26.9 inch diameter rear tires, top speed in each gear is precisely the same as it is in a stock Z8, so streetability is not an issue. Plus, as a result of the slight increase in rear tire diameter, my speedo is now dead accurate! Again, Steve Dinan really is a wizard when it come to these things and I have learned to trust his judgement implicitly. The other area I have worked hard on is removing weight from the Z8 and Dinan's engine and exhaust mods have helped me get the car down under 3500 lbs. curb weight (full gas tank). Since a stock Z8 weighs 3685 lbs., I am approaching my goal of removing 200 lbs. from the car and plan to pass that level this winter when I install new lighter weight seats. Lowering the overall weight of the Z8 makes it feel more nimble, noticeably reducing overshoot in handling, and the removal of 200 pounds is roughly equivalent to adding 20 more horsepower. Perhaps the biggest improvement stems from the reduction in unsprung weight achieved by running lighter weight wheels, tires, and brakes which allows the suspension to react much more rapidly to road imperfections thus keeping the tires in better contact with the road. Despite the overall stiffness of the suspension, I find the ride quality quite comfortable, having thoroughly enjoyed my very rapid trip back to Montana from California. If most of my driving was on rough pavement, or if cruising was my priority, I'm sure I would take a different approach, with the Alpina set-up at the top of my list, so the direction I'm going in with Dinan may not appeal to others. I will keep everyone up-to-date as we proceed in case it proves of interest.

  6. #6
    That does sound really interesting, and you are certainly lucky to live in a land of suitably surfaced sporting roads. California used to have such great roads, it was one of the reasons I moved here, but sadly they just don't seem to maintain them like they used to, all my old favorites from my mototrcycling days are falling into bad repair out here now.

    I look forward to hearing how your work progresses, and I'd also love to hear how it is on the track should you ever get the chance or inclination. I would be more than happy to set up a track day at WSIR's big track, which is the track that would best suit your car. It would be wonderful to have a day out there with such a well sorted machine, and to have Steve drive it too. Food for thought anyway.

    Funnily enough I was rather interested in Steve's sugestion of the M3 steering rack adaption becuase when I get into my Z8 from either my SL500 or the Exige S I notice that it requires a lot more rotation on the steering wheel for the same amount of turn. I don't really feel it once I'm out on the open road road, but on the little twisty lanes that wind up the hill to my house I can really feel the difference. I haven't done an exact measurement of this, but it seems to make the same turn in the Exige S takes about 12 minutes rotation on the steering wheel, 15 on the SL but almost 20 on the Z8. As I said I never really notice this out on the open road as the steering inputs tend to be much less than on the corkscrew lanes that wind up to my house, but it did seem like something that would be interesting.
    Andrew Macpherson

    Expert Z8 Inspections, with full support for both Z8 sale and purchases.

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    My experience with the steering ratio on the Z8 mirrors yours exactly. There are times when a faster ratio would be beneficial (really tight hairpin turns) but under most circumstances, the standard ratio is just fine. The reason I am somewhat reluctant to change the rack on my car is I don't want to end up with steering that is what I would call "twitchy", i.e., never let's you relax. Knowing Steve, he won't do anything to the car that isn't an improvement so I'm sure we will explore the option and I will report on the findings. Given that the Z8's OE steering rack has suffered some reliability issues, perhaps finding an alternative would be of benefit on more than one level. I do know what you mean about the roads in California deteriorating although I must say some of the best driving roads I have ever experienced are located in Northern California. In particular, there is one stretch the locals refer to as "the racetrack" and although parts of it aren't in the best shape, playing with my Z8 on those never-ending twistys was absolutely thrilling!

  8. #8
    Z8 Ate My Homework! Norcal's Avatar
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    "the racetrack", What road in N. CA?

  9. #9
    Administrator thegunguy's Avatar
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    I too would prefer a better/more attractive solution. However, should there be an actual frame problem, I would rather leave the BMW PP in place. Otherwise, they might attempt to dismiss their liability due to the use of the aftermarket brace.

    Again, I'm certain Dinan or others would make a better unit - just hesitant.
    thegunguy

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    North of Santa Rosa, the road from Warm Springs Dam to Stewart's Point. First part is some of the finest high speed curve driving I've ever experienced. Rest of the road is super twisty and very challenging. Has been discovered, especially by motorcyclists, and is now heavily patrolled on weekends, but weekdays are pretty clear. Enjoy!

  11. #11
    Team Z8 jawz's Avatar
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    That is one fantastic road! I recommend it at least once if you're ever in that area. Trust me when I say - you'll definitely want to drive it more than once.