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Thread: Changing seats

  1. #1
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    Changing seats

    Over the years, I have extensively modified the OE seats in my Z8 and now find them to be much more supportive and extremely comfortable. However, they are also quite heavy, somewhat limited by design in the amount of support they can provide, and preclude the use of race harnesses. As a result, I have been on a quest to find alternative seats for many years now and have finally come up with a set that I think will work.

    The problem with trying to fit different seats in the Z8 is the cockpit is very narrow, particularly in the shoulder area, and most modern seats have big shoulder wings that preclude their fitment in the Z8. They also tend to be too wide in the base area making it difficult to accommodate the adjustment controls. Finally, racing harnesses require very specific mounting points and the Z8's lack of a rear seat makes their adoption particularly difficult.

    After much searching and measuring, I have found a Corbeau seat which does fit in the Z8's cockpit. The weight difference is app. 20 lbs. per seat (including all mounting hardware and seat rails) so I can remove at least 40 more pounds from the car. The seating position should be slightly lower, which will lower the car's CG (with me in it) and along with the higher fixed headrest, help reduce wind buffeting with the top down. No one makes installation brackets for a Z8 so I am adapting universal ones from Corbeau. The one drawback to these seats is they are designed to fit very snugly and probably won't accommodate large bodies. The harness installation is a bit trickier but after much experimentation, I have come up with a way to make them work without sacrificing the convenience of the retractable OE set-up. Schroth makes a retractable 3-point harness that has an on/off switch to disable the retractable mechanism. This means I can lean forward without restriction when necessary but lock the harness up tight when I want maximum support. Of course, in the unlocked mode, if the retractable mechanism senses a significant change in side-to-side or for-and aft-force, it locks up the harness just like the OE belts. Finding an appropriate mounting point was the biggest challenge and it will require an addition to the roll bars but should be virtually invisible when finished.

    This modification is not for the faint of heart and with my Z8 back at Dinan's for more massaging, I won't undertake it until later this year. I will report on the final results when it is completely sorted but I really look forward to being able to strap into a very secure driving position.

  2. #2
    Z8Mania
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    GM- you are the man. I love that you have really put the time and effort into all the positive modifications to the Z8. I cannot wait to see how yours comes out as the uber Z8

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    Thanks for the kind words but I think it's more like being foolish enough to enter where angels fear to tread! I've still got to figure out how to get the seatbelt and airbag sensor systems to integrate with the new seats and belts. Right now, the seat belt and airbag sensors are dependent upon a weight sensing panel built into the OE seat cushions and the seatbelt system requires the OE buckles to be buckled. Bypassing is one option but I really don't want to live with warning lights glaring at me all the time. I will attempt to convince the system that the seats are occupied and buckles buckled but the electronics involved may prove problematic. Are we having fun yet?

  4. #4
    Z8 Addict Z8doc's Avatar
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    I posted awhile back regarding the CG lock. This device really makes a difference and keeps your rear planted firmly on the base cushion of the stock OEM Z8 seat, whether on the track or in spirited mountain twisties and highly recommend it for the average Z8 owner. At less than $50 USD, it is a much bigger bang for the buck when compared to replacing the whole seat with modifications.
    The post is in this same section of the forum, just two down from this thread.

    I too wish the Z8 seat was better for driving and often wondered if the Z4 seat (which is a very narrow seat too) would retrofit in the Z8?
    Last edited by Z8doc; January 20th 2008 at 03:58.
    Best Regards,

    Jeff
    61995 Silver /// Rot - Original Owner
    Z8 Club of Germany e.V. #102

  5. #5
    Somehow I missed this, did you guys see the Euro GT3 seats that these Japanese guys put in the Z8. They are the best sport seats I've sat in to date, and light too, at only around 28lbs each if I remember rightly. They might look a bit oversized with the top down - but maybe like Dumbo ears you'd get to love 'em?
    Andrew Macpherson

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

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    I have been using the CG locks for the past few years and your comments are right on. Definitely the best alternative to changing seats in a Z8, although those seats can be noticeably improved by judicious applications of stuffing to make them fit your body contours better. I currently enjoy significant lateral support in both the base and back portions coupled with a big improvement in the lumbar region. Still look OE; just work better.

    I had seen the GT3 seats in that black Z8 some time ago but was not convinced they really fit the Z8. Having researched the problems involved rather extensively, I don't believe those seats will allow adequate rear movement because of the wing size and if you look carefully at the photo, I think you will see that the seats are way too close to the steering wheel. I would also be surprised if the seat controls were conveniently accessible since most seats are too wide in the base area making it difficult to impossible to operate the tilt controls. My guess is they installed those seats as part of the "show car" presentation but I doubt they were practical. You are right about them being great seats, however. Remember, too, when comparing seat weights that the mounting brackets and adjustment rails will add a substantial amount to the overall figure. The Z8 seats weigh just over 60 lbs. each but that includes the mounting brackets, adjustment rails, etc.

  7. #7
    Sounds right to me, on second looks they do seem very far forward! Those seats have no controls built in, they only go back & forth on their sliders, which is what makes them so light compared to the US spec Porsche seats that have all the electric controls, and like ours weight in at over 60lbs each. I had never really put my mind to this, but if comfort is the primary goal one may well be able to re-upholster the stock seat to give it more support, but that won't take out any weight.

    If weight reduction is your primary goal you may want to have a look at some of the carbon seats that go into the Elise/Exige, they are down to about 7 pounds with padding. You'd have to get your own fitting machined up, but I think that should be pretty easy for Dinan to do.
    Andrew Macpherson

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  8. #8
    Z8 Addict Z8doc's Avatar
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    How did you accomplish this?

    Quote Originally Posted by Grease Monkey View Post
    ...can be noticeably improved by judicious applications of stuffing to make them fit your body contours better. I currently enjoy significant lateral support in both the base and back portions coupled with a big improvement in the lumbar region.

    Did you have to redo the leather or did you over stuff the bolsters from behind with the seat back off? and... what material did you use?

    Can you post a pic of your seats for me to see?
    Best Regards,

    Jeff
    61995 Silver /// Rot - Original Owner
    Z8 Club of Germany e.V. #102

  9. #9
    Z8 Ate My Homework! Norcal's Avatar
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    Would a "Race" seat with tilt forward (non-adjustable) seat back, rather than full fixed, be required in order to reach the bins behind the seats? Look at the new seats Porsche is putting in the US. Carbon fibre buckets with a flip forward back...really cool, but very expensive. Not sure on the weight. Unfortunately, they weren't an option yet when I got my GT3 & RS.
     
    Last edited by Norcal; January 21st 2008 at 00:14.

  10. #10
    Those are the coolest OEM chairs I've seen, but in our car they'll keep your neck well chilled!
    Andrew Macpherson

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  11. #11
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    Within reason, there is plenty of room within a Z8 seat's structure to add padding and the leather cover will easily accommodate the increased volume. If you remove the seat and take off the back cover, you gain access to the critical areas for passenger support: bottom and back bolsters plus lumbar region. I use a combination of high density closed cell foam (think ground pad used for sleeping while camping) and 1/2 inch thick felt. You just start cutting pieces and stuffing them into the requisite areas until you obtain the proper fit for your body. To prevent bulges and ripples from showing through the leather cover, it is necessary to taper the pieces you insert to blend smoothly with the existing shape. If done well, there is really no evidence of the modification except in the way the seat holds you in place. Expect some skinned knuckles in the process due to the sharp edges of the internal framework and don't be surprised if you end up doing it more than once since the new materials you are adding will tend to compress over time and the fit will loosen up a bit. That's one of the reason's I like to use the felt material since it doesn't compress nearly as much as the foam. I also try to overstuff each area in anticipation of the compression so the fit, at first, might be a little too tight. Of course, a better approach might be to take the seat to an auto upholstery shop and have them remove the leather covers so you can gain direct access to the internal structure and then bulk up the contours to provide better support, but you might find that the cover will no longer fit when you are through. If you use my stuffing technique, you should plan on unhooking some of the material fastening rings (aka hog rings) to provide better access to the insides of the seat structure and you can replace them with new ones which are available at most hardware stores.

    My problem with many modern seat designs is that they just don't look right to me in a Z8. While I am always interested in reducing weight in my car, I am not willing to pursue that goal at the expense of aesthetics. This often leaves me in a quandary since my tastes run to more traditional automotive designs like the Z8 while so much of the newest technology has a high-tech look that just doesn't blend well with swoop. I'm not a complete purist (19" BBS wheels and judicious applications of exposed carbon fiber, for example) but if I'm going to put new seats in my car, I want them to look reasonably appropriate to the aesthetic of the Z8's design. I'm not sure the ones I have chosen are the best looking but they may be the only ones that will fit well and still look at home in the Z8. Once I have completed the project, I will have a much better idea of what the real considerations are when changing seats and perhaps there will be other seats I can consider for the future. In the mean time, saving 40 lbs. while retaining a reasonably traditional look works for me.

  12. #12
    Sounds very well reasoned to me, I look forward to seeing the new seats in place.
    Andrew Macpherson

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

  13. #13
    Team Z8 ZMates's Avatar
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    any update?

  14. #14
    Team Z8 riverflyer's Avatar
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    yes, I am interested as well. The heat is a must have option. I have a set of these very light cf Cobra seats in my garage as I sold the car they were intended for.
    Now you have me thinking.....
     

  15. #15
    Z8 Addict Scott Pettit's Avatar
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    Are you going to try and match the stitching on the dash, side panels and center consul?
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  16. #16
    Team Z8 riverflyer's Avatar
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    I guess I was more "thinking out loud" as I agree with GM that lighter more supportive seats might be nice and I had these seats waiting for the right situation. I had not thought of them for the z8 before and would have to see how they look, if they fit and then retrofit heating, which is no big deal. Off the top of my head, i doubt they would look right w/o following up, as you say and tying them into the interior more thoroughly.

  17. #17
    Z8 Addict Scott Pettit's Avatar
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    Plus, and this is just a question and not an implication, how comfortable are racing seats on long drives?
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