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  1. #1
    Join Date
    Oct 2014
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    Bucks
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    16

    Spring rates and colours

    Hi All,

    i've just got to the stage where I've taken my Sumo chassis (with engine/ gearbox installed) off the axle stands and put down it on its wheels. I've preloaded the springs but it has a bit of a nose down stance with about a closed fist distance between the sump and the ground. How much clearance does everyone else have between the chassis and the ground?

    The engine is a small block ford with white front springs and black rear springs which are a higher spring rate. I did double check with Pilgrim way back on the build and was told that it was correct to have a higher rated springs at the rear.

    Any views? Does it really run that low? Maybe I need to reduce the preload to bring the rear down or even replace the front springs to bring it up.

    Many thanks for your views in advance

  2. #2
    Join Date
    May 2004
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    Cowbridge, United Kingdom
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    62
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    9,988
    I assume you have adjustable coil over dampers?
    It sounds like you need to wind them up a bit.
    Kev Davies
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  3. #3
    Join Date
    Dec 2008
    Location
    Newcastle upon Tyne
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    1,888
    Hi ?,

    Details of spring weights below - it might be worth confirming these with Pilgrim as it was compiled (from various scraps of information) sometime ago.

    There have been numerous threads over the years discussing the Sumo spring rates, a search on the forum should find them;

    Hope this helps


    Regards,
    Ian


    Sumo Spring Weights

    Rate Colour
    160 Green
    220 (or 270) Purple
    450 Red
    500 Yellow
    550 White
    600 Blue
    700 Black (or Silver – according to Den’s post 26-Nov-2013)
    Pilgrim Sumo Mk3; IVA Apr. 2014; RV8 3.9 EFi ; Cosworth T5; Granada Donor
    Phase Two underway - Conversion to Japanese

  4. #4
    Join Date
    Mar 2006
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    From memory I thought that the stiff springs went at the front of the car, I think that you have yours the wrong way round, i.e. the softer ones at the front.
    You state that you have checked with Pilgrim which is fair enough but clearly you are not happy with the setup, it makes sense to need the stiff springs at the front as you have a heavy engine block more or less on the axle line.
    Last edited by Sidecarbod; 15-09-16 at 08:13 AM.
    This forum has a high proportion of people that lack basic manners.

  5. #5
    Join Date
    Feb 2007
    Location
    West Sussex
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    8,878
    .... and the cars do sit lower than your tintop....about 3.75" on my RV8 I think between sump and ground.
    Crendon Chassis No.49
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  6. #6
    Join Date
    Feb 2011
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    4,142
    Quote Originally Posted by KevinW View Post
    .... and the cars do sit lower than your tintop....about 3.75" on my RV8 I think between sump and ground.
    *measures fist* Which equates to roughly one imperial fist
    My DeDion build diary..
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  7. #7
    Join Date
    Jan 2009
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    Dronten, the Netherlands
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    Quote Originally Posted by Sidecarbod View Post
    it makes sense to need the stiff springs at the front as you have a heavy engine block more or less on the axle line.
    That's what I thought initially as well, but what comes into play is the geometry of the arms and spring. You can imagine the back spring mounted "halfway" the arm, effectively only pushing half its weight at the wheel, where the frontspring might work at a 1 to .8 ratio. Not sure if this applies to the Sumo, but possible.

    BR, Theo
    Not for the faint hearted, not for the shy...

  8. #8
    Join Date
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    Quote Originally Posted by Wetpool View Post
    That's what I thought initially as well, but what comes into play is the geometry of the arms and spring. You can imagine the back spring mounted "halfway" the arm, effectively only pushing half its weight at the wheel, where the frontspring might work at a 1 to .8 ratio. Not sure if this applies to the Sumo, but possible.

    BR, Theo
    I get what you are saying which is basically that the leverage ratio of the wishbones at the front and the swing arms at the back will have an effect on the spring rate required. I think that you might have it the wrong way round though, if you take the back end swing arm which is mounted more or less in line with the back of the seats with the wheels mounted at the other end, if the spring was mounted at a point mid way between the pivot an the wheel then it would move vertically half the distance that the wheel moves but the spring would see twice the load that it would see if it was mounted directly behind the wheel. Having said all that from memory the rear shocks are more or less in line with the centre of the wheels. They are in-board of the wheels and this will also have some leverage ratio associated with it being in this position. The same thing applies at the front, the shocks are in-board so a ratio will be applied! (Like you said!)
    This forum has a high proportion of people that lack basic manners.

  9. #9
    Join Date
    Oct 2014
    Location
    Bucks
    Posts
    16
    Hi All,


    Thanks for all your replies about the ride height on my build. I have wound the adjuster for the spring quite a way up on the front but it's now just compressing the spring and I can only just get the tip of my finger between the coils. I think if I go much further I will end up with the coils binding as the suspension operates. The chassis at the front is about 5" off the ground but the sump is only 1.5". It's possible I might need a shallower sump for the engine.


    Based on the table of coil colours above I have 550lb on the front and 700lb on the rear. Looking at the new Pilgrim online shop they recommend 550lb on the front and 450lb on the rear for the Chevy engine. As far as I know the Ford unit is quite compact and mine has aluminium heads so I wouldn't expect it to weigh more than the Chevy. I have read an older post from 2014 about the spring rate being higher at the rear to compensate of the leverage of the rear arm and to stop the rear squatting when you give it some welly.


    I spoke to John at Pilgrim today and he told me that they are currently publishing a technical update about the spring rates which they will publish soon on their website.
    John also pointed out the fact that my car is still on its old steel 14" slave wheels, which would also make it sit lower as well


    I did laugh about the imperial fist measurement, it's like a metric adjustable spanner .


    How far off the ground do other people's chassis sit?


    Russell

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