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Suspension Cones 
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Post Re: Suspension Cones
John,

Have you got your competition dates all sorted out?

David

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Tue Mar 03, 2015 9:17 am
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Post Re: Suspension Cones
Hi David, 5 out of 6 over three weekends sorted, starting With Wiscombe at the end of April, Werrington Park 2-3rd May, Stoneleigh on the 4th May, Mira 9th May and the only event not posted yet Llys Y Fran on the 10th May, then back home the following Wednesday/Thursday, with a few jaunts up and down the country collecting bits of bike or GTM, its all go, just remains to decide do I go Turkish or Egypt air.
Cheers
John


Tue Mar 03, 2015 11:39 am
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Post Re: Suspension Cones
A little late to the party but I'd be very interested in understanding the various options on cones/roll bars etc. My gut feel is that Starmag is heading in the right direction with smootharides on the front and standard rate on the back for a road car with the addition of a (light) front anti-roll bar to keep things tied down.
West I'd be interested as to what you based your calculations on in terms of spring rate as neither Minispares or Minisport could supply any data. Nor could Alex Moulton when I contacted him before he passed away. The only source I've seen for the variable rate of Mini springs is in an IMechE paper that was written in the late 60s. Unfortunately I've lost the copy I had but if any of you young engineering types are in the IMechE you might be able to find it in their archive -- it was co-written by some people at Dunlop. I did pursue the possibility of having cones measured but the quote of £600+ wasn't affordable.
Another issue to consider is that the overall rate is also affected by the type of trumpet used -- the HiLo and Adjustaride trumpets have a different shape to the standard part which affects the way the spring is compressed and thus the rate. In all a very complex subject with lots of permutations -- 5 different springs -- standard, hard and race plus front/rear smootharide and 3 types of trumpet. There's also a possibility to use a Hydrolastic top arm which raises the wheel rate as the leverage ratio is different.
For what its worth my plans are:
White car -- track use -- standard springs all round with hydro arms at the rear
Red car -- road use -- standard rear/smootharide front
Timing -- in my dreams!
Steve


Tue Mar 10, 2015 4:08 pm
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Post Re: Suspension Cones
I have some ideas for a rig to test installed spring rates, just need some time to do it. Im currently in Miami so on the flight back I may put pen to paper on the rig for the first brainstorm

Neil

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Thu Mar 12, 2015 3:10 am
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Post Re: Suspension Cones
I have watched this thread with interest and looked at all the pros and cons, I have a set of std rubber cones with Hilows very little used in my Twinny. I have a pair of Mini front coilover Spax shocks waiting for me in Devon and 4 AVO shocks 2 with 330lb springs ex my Jedi.
I do favour the coilspring setup as at least we are talking known quantities when it comes to spring rates :lol: so I'm going to order a set of softer "townride" coils from Steve Sheldon and use coilover shocks at the rear as a helper spring to stiffen the heavy end and hopefully still have the longer travel I will need with our rough roads :wink:
John


Fri Mar 13, 2015 10:27 am
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Post Re: Suspension Cones
Anybody got any dimensions for the altered lever ratio hydro upper arms compared to the std mini upper arms?
Cheer
John


Sun Dec 13, 2015 4:13 am
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Post Re: Suspension Cones
I couldn't find any reference to this in the Mini literature other than a recommendation to use hydro arms in Bill Sollis' book which is biased towards Mini Miglia cars so I thought I'd have a quick measure of the parts on the car. The figures below were taken with the parts in place with a tape rule and so may have a perceived level of accuracy beyond the measuring process. So....

Hydro Dry
Arm length (mm) 172 172
Spring knuckle cup from pivot (mm) 45 34
Ratio 3.8:1 5.1:1
Ratio squared 14.5:1 26.1:1

As the spring is on the same side of the arm axis as the wheel we're dividing the spring rate by the ratio -- actually ratio squared according to Staniforth's book -- to get the wheel rate. Therefore the wheel rate with a hydro arm is 80% higher than the dry arm. I'm amazed!! Or is there something wrong in the calculations?? If this is right then standard springs with hydro arms might be a little too stiff -- possibly a bit too much oversteer?

Please feel free to check, re-calculate, critique as I may have got this all wrong.

Steve


Wed Dec 16, 2015 12:18 pm
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Post Re: Suspension Cones
Typed that as a table which got screwed up so lets try again with the figures:

Hydro
arm length (mm) 172
knuckle position (mm) 45
ratio 3.8:1
ratio squared 14.5:1

Dry
arm length (mm) 172
knuckle position (mm) 34
ratio 5.1:1
ratio squared 26.1:1

Steve


Wed Dec 16, 2015 12:26 pm
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Post Re: Suspension Cones
Hi Steve,
I have a dry upper arm on the bench and its length from inner pivot to outer hub ball joint is 6-3/4” 171.45)and from the inner pivot to knuckle socket center is 1-5/8” (41.27) (I think your measurement of 34mm is off) my chances of getting my eyes on a Metro arm are zero, but I was thinking instead of moving the knuckle out to stiffen the spring as Bill Sollis would do for a circuit race car, why not move the socket inboard to soften the spring, instead of soft springs for front and hard for back.
When I only had L-H upper arms I fabricated from steel tube a pair of upper arms thinking I could use coil over shoks on the front, but I could also fit a knuckle socket in a new location to soften the springs, If it was OK for BL to move out why not for Kano to move in??
As BL was all inches back then I would guess the hydro knuckle socket would be 1-3/4” (44.45) and it is worth trying upper arms with knuckle sockets moved to 1-1/2”
Just a thought
John


Wed Dec 16, 2015 6:37 pm
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Post Re: Suspension Cones
I have a rough design of a rig to test on the car the wheel spring rates, that is as far as it has got unfortunately. I need to do some calcs to check it will be stiff enough for the job, but this is currently sitting down the list a currently. I am hoping to determine true fitted wheel rates for my car before I go to coil over.

Neil

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IF wile e coyote had a GTM he would have one with Nitrous too! watch out road runner! The First GTM into the 11s then the 10s, PB 10.87 @ 125.5 Mph on A048 tyres, and fully road legal at Santa Pod


Wed Dec 16, 2015 10:25 pm
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Post Re: Suspension Cones
John,
I had to measure from the outside to the knuckle positions so may have made mistakes -- one dimension we agree upon is the 6 3/4" which I rounded to 172mm. I recollect a reference to a 5:1 front arm ratio so I'll try to track down some more info if I can unearth my Mini technical files -- probably still in a box after the house move! The hydro arm I'm using is Mini -- NOT Metro -- availability like hen's teeth but I happen to be modifying a hydro Mini to coil over when I get round to it. I think your idea is sound BUT beware of moving the position too far -- the trumpet is canted over more due to the effective mis-alignment and may affect the ball joint -- on the hydro arm this effect is on full rebound -- with your scheme I'm thinking this will be on full jounce and less obvious -- need to check the ball joint has enough travel and won't lock up/wreck the cup.

West,
As above I'm moving to coil overs on the Clubman mainly to move away from hydro and as I want to try a rear beam ilo the subframe to reduce weight. One thing to be aware of is that coil overs will not have the rising rate of the Mini doughnuts which helps cushion the suspension as the actual jounce travel is very small -- 2 1/2" - 3" on a car with standard ride height. With a linear rate you may find that the suspension is hitting the bump stops more often resulting in a sudden (major) increase in wheel rate -- may need some (more) progressive bumps stops similar to the old ST hydrolastic upgrade package if they're still available! Alternatively use those progressive coil springs that sit in the subframe as a direct replacement for the doughnuts. As a aside using coil overs on the standard Mini front mountings actually results in a reduction in rate on jounce as the dampers start to lean outboard. Exactly what you don't want! The guy at Huddersfield Spares recommends some significant fabrication work to move the upper mount inboard to address this issue -- this is probably beyond my welding skills as it involves cutting into the end of the bulkhead cross beam that supports the subframe top mounts

Steve


Thu Dec 17, 2015 8:04 pm
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Post Re: Suspension Cones
I'm making a pair of sockets for the knuckle ball's and will tack them into a plate and fit into the the fabricated upper arm to trial assemble without the coil spring to see how it looks, BL looks to have moved the socket out 1/8" I will try the opposite 1/8" in to soften the settup.
I'm interested in your Mini beam settup as my Twinny has gat a big hole in the back and my get revived after the GTM is going :lol:
John


Fri Dec 18, 2015 4:09 am
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Post Re: Suspension Cones
John -- you have a PM
Rgds
Steve


Fri Dec 18, 2015 11:14 am
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