Duchess Rear Shock Replacement

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  • #234794
    Jonathan Annear
    Participant

    @bigband39

    Now that I have replaced some badly worn by-ply tires with properly inflated radials, my ride has improved. As mentioned in a previous tread, looking at my car from the driver side drives me nuts though as I am cursed with negative camber and my passenger side sags lower than the drivers. Before taking the car in for alignment, I am replacing some badly worn shocks. Considering that the body of my Duchess blocks off access to the torsion bar adjustments, I am considering these to correct and balance out my rear ride height . . .

    http://www.dealparts.com/product/00-9570-0.html?gclid=CKOog7zMorgCFQae4Aodg0YAuA

    For the twelve Duchess owners on here, I am wondering that they are running and if they have had any similar issues. I’m not sure if anyone else has the same upper modified mounts for the rear shocks and my main concern is with clearance. I think air shocks would prove to be larger and wouldn’t fit, which is why I decided against them. Any help as always is appreciated. PMOSSBERG2013-07-09 14:57:22

    #256956
    Royal
    Participant

    @royal

    I had enough room to put coil over springs around the existing shocks.  Works well and looks good. Not some cobbled up job.  

    However, if I had to do it again, I would try the shocks like you are linking to.  I think that they will do the job and also provide some measure of adjustment.  Good luck.  
    #256957
    KentT
    Participant

    @kentt

    Do you really need the stiffness of coil-overs with this lighter-than-stock car?  

    Personally, I’d consider a pair of KYB gas-adjust shocks without the springs.  Your mileage may vary…

    Early FF TDr on 69 VW pan
    Slowly coming back from the ashes...

    #256958
    Jonathan Annear
    Participant

    @bigband39

    I don’t think that the Gas-Adjust shocks would remedy my passenger side sag issue though, would they? After talking with you Royal, I was considering the set up that you have. I’m just not sure that I would have clearance for the top cup with my set up. Would correcting the height effect my camber? Has anyone done any adjustments to rear camber? After hours of research, I still have no clear answers.BIGBAND392013-07-09 11:32:55

    #256959
    Royal
    Participant

    @royal

    Kent, you ask a good question as usual.  Normally, I would see no need for helper/coil overs on a lightened vehicle.  But, my port side was down a lot and the only reason(s) I could come up with are that the builder mis-adjusted the rear torsion bars before he put the tub on or that the previous owner weighed 562 pounds and I was looking at some rather serious torsion bar weakening.  I considered the gas adjust and the coil springs but went with the cheapest available.  You can see my installation in the photo gallery (I am member 18705).

    #256960
    Paul Mossberg
    Keymaster

    @pmossberg

    I’m running stock VW shocks. Oil. Not gas.

     

    The general principal is that shocks have one purpose, controlling jounce and rebound. They should not be used to control ride height.

     

    I understand your issue with not being able to access the rear torsion tubes. But forcing the car up with coil-overs just seems like bad idea.

     

    I’m not a suspension specialist. Nor am I an engineer. And there are many folks here smarter than me. But…

     

    The car is sitting at a certain static height relative to the torsion bar suspension. If you force the body to ride higher with coil-overs, aren’t you artifically un-loading the torsion bars? Is that bad? I’ve no idea. But like I said above, it just doesn’t sound like a good thing. At a minimum, it would seem you are going to end up with a stiffer ride than you want.

    Paul Mossberg
    Former Owner of a 1981 Classic Roadsters Ltd. Duchess (VW)
    2005 Intermeccanica Roadster

    If you own a TDr and are not in the Registry, please go to https://tdreplica.com/forums/topic/mg-td-replica-registry/ and register (you need to copy and paste the link)

    #256961
    Jonathan Annear
    Participant

    @bigband39

    I thought of the coil overs almost as a helper spring that would only take so much of the load until the torsion bar suspension kicks in. This mentality comes my history with helper springs in leaf suspensions on Jeeps, which of course are a completely different animal. I still don’t understand how the torsion bars have anything to do with my camber. Considering that my ’71 chassis has the spring covers blocked by fiberglass of the kit car body, can I achieve enough adjustment by elongating the holes? When the car is jacked up, the camber does correct itself. Does anyone have any pictures of a modified spring arm and the adjustment they made to fix a negative camber issue?

    #256962
    Royal
    Participant

    @royal

    Paul, in a very few months, I turn 72.  Believe me, I know about stiff!  

    You are correct that if you add coil-overs you are transferring some of the weight from the torsion bars to the new coils.  My car was riding un-naturally low on the port side.  I do all my own work and will until I sell my TDr.  If my intended job is so difficult that it takes 2 people or I have to take it to a shop, I simply either don’t do it or I find another way.  

    I looked carefully at pulling the tub and decided that I could not do that alone.  Thus my solution was to restore the correct height using the coil overs.  (I used the weakest springs that I could find which were Superior 750# springs.) And of course, the way that they work is to increase the lift by increasing the spring rate which will increase the ride stiffness while raising the rear of the TD.  As it turns out, my fix did not make the ride so stiff that I find it objectionable, and it was relatively cheap and fast, and it did restore the ride to correct height.  I will be the first to say that I was lucky here since it is next to impossible to predict the effect that these extra springs will have.  I did do a little unscientific testing by putting a bathroom scale on top of my floor jack and gradually lifting the TD until I had 300# registering on my scale.  At that point, it looked about right and I went ahead with the coil overs.    
    If either of my boys lived closer, I would have pulled the tub.  
    #256963
    Paul Mossberg
    Keymaster

    @pmossberg

    Good analysis.

     

    Thanks Roy.

    Paul Mossberg
    Former Owner of a 1981 Classic Roadsters Ltd. Duchess (VW)
    2005 Intermeccanica Roadster

    If you own a TDr and are not in the Registry, please go to https://tdreplica.com/forums/topic/mg-td-replica-registry/ and register (you need to copy and paste the link)

    #256964
    Mike Schumacher
    Participant

    @juneybug

    If you look in – my project – juneybug there is 1 photo of a spring plate and how I decambered both sides 1 spline. I am working with a VW pan with no MGr parts on it yet, so completely accessible. Also a simple swing axle. I did not access the torsion bars and I don’t have any lean so what I did won’t fix your issue but FYI.

    #256965
    Jonathan Annear
    Participant

    @bigband39

    Thanks, JuneyBug. Although I appreciate the help, my vehicle having IRS and having everything blocked off makes things a whole different animal. As an update, I decided to simulate correct spring positioning by jacking the right side of the vehicle up to be even with left. When I did, it seems that my camber issue resolved itself. Does that make sense?

    #256966
    KentT
    Participant

    @kentt

    BIGBAND39 wrote:
    Thanks, JuneyBug. Although I appreciate the help, my vehicle having IRS and having everything blocked off makes things a whole different animal. As an update, I decided to simulate correct spring positioning by jacking the right side of the vehicle up to be even with left. When I did, it seems that my camber issue resolved itself. Does that make sense?

    Absolutely makes sense.  If the rear of the car is level, side-to-side, then the wheels should be straight up.  If one side is lower, the wheel on the other side will tilt toward the low side, and the wheel on the low side will tilt outwards at the top….

    Early FF TDr on 69 VW pan
    Slowly coming back from the ashes...

    #256967
    Jonathan Annear
    Participant

    @bigband39

    I hate to revive an old post, but I believe a couple of the most active members on the thread are still on the forum.  I have finally installed the coils and the ride is fanastic!  😛  The harshness I worried about is non-existent and the car is nimble on the roads. The only problem I face now is that somehow the driver’s side still sits lower than the passenger.  This is baffling, as I know I have taken the load off the torsion bars and there is equal load on both sides.  😕  Aside from that, I now have positive camber on passenger side as well.  The springs come from the factory at the lowest point.  They can be turned counterclockwise as an adjustment.  This would compress the spring and, if I’m not mistaken, increase the load on it while shortening the length on the spring slightly.  Would this fix my issue regardless of the comfort of the ride?  Aside from that, there is also a threaded rod that runs from the frame of the Duchess to the top of the shock tower.  Would an adjustment forward or backward adjust for camber as well?  Thanks for any answers. 

    #256968
    Paul Mossberg
    Keymaster

    @pmossberg

    I can handle the easy one…

    The threaded rod running to the top of the shock tower has nothing to do with suspension. It’s sole function is the support the rear subframe (which is under the rear splash pan fiberglass). Adjusting it would move the rear of the body up or down, relative to the VW pan.

    Don’t think I’m smart enough to chime in on the coil overs and their relationship to ride height. But I do have a question.
     
    In your initial post you said the pasenger side sat lower than the driver side. But now you wrote “… the driver’s side still sits lower than the passenger….” What changed?
     

    Paul Mossberg
    Former Owner of a 1981 Classic Roadsters Ltd. Duchess (VW)
    2005 Intermeccanica Roadster

    If you own a TDr and are not in the Registry, please go to https://tdreplica.com/forums/topic/mg-td-replica-registry/ and register (you need to copy and paste the link)

    #256969
    Jonathan Annear
    Participant

    @bigband39

    If it moved the rear of the body up and down relative to the pan, would that correct my body height issue on the passenger side. I should have taken some before and after photos, as I think you are correct.  The passenger side did sit lower and now sits higher. 

    #256970
    Paul Mossberg
    Keymaster

    @pmossberg

    Adjusting that threaded rod is not going to change the “body height relative to the pan.” The body is bolted to the pan.

    It
    is going to raise the rear a little, opening up the wheel well. But it
    will also affect  the alignment of the doors within the door opening and
    will throw off the roof attachment.

    Paul Mossberg
    Former Owner of a 1981 Classic Roadsters Ltd. Duchess (VW)
    2005 Intermeccanica Roadster

    If you own a TDr and are not in the Registry, please go to https://tdreplica.com/forums/topic/mg-td-replica-registry/ and register (you need to copy and paste the link)

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