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My brain really isn't what it was. I'm sure I used to know how to work out required spring rates from fairly simple given parrameters. Can't recall any of it right now...
Basically the Cortina springs are way to hard. The more I think about it the more I think I need to have a good look at the suspension. The springs need to be changed and I need to work out what rates I need.
Next up I would be intregued by the idea of using modern style variable rate springs on the car but have no idea about how these are rated or who can supply them....
finally a related buyt unrelated question - driveshaft angles on lowered RWD cars... to avoid feedback or other problems am I better switchig to a two-piece prop with a centre bearing/carrier arrangement or using a single piece prop...? I know the angle is lessened by using the longer run of a single prop but I am trying to calm some unwanted shocking related to the back axle and prop to the box. Obviously I'll reduce driveline harmonics going for a 2 piece prop too.
Cheers
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1941 Wolseley Not Rod - 1956 Humber Hawk - 1957 Daimler Conquest - 1966 Buick LeSabre - 1968 Plymouth Sport Fury - 1968 Ford Galaxie - 1969 Ford Country Squire - 1969 Mercury Marquis - 1970 Morris Minor - 1970 Buick Skylark - 1970 Ford Galaxie - 1971 Ford Galaxie - 1976 Continental Mark IV - 1976 Ford Capri - 1994 Ford Fiesta
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shameless rescue from P2 of the forum...
worth pointing out I have no idea what the current spring rates are - just that they are -2" 'sport springs'.
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1941 Wolseley Not Rod - 1956 Humber Hawk - 1957 Daimler Conquest - 1966 Buick LeSabre - 1968 Plymouth Sport Fury - 1968 Ford Galaxie - 1969 Ford Country Squire - 1969 Mercury Marquis - 1970 Morris Minor - 1970 Buick Skylark - 1970 Ford Galaxie - 1971 Ford Galaxie - 1976 Continental Mark IV - 1976 Ford Capri - 1994 Ford Fiesta
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less vibe from a 2 piece prop but single piece is stronger, either way the uj angles should be fine, you can suffer from wear if the prop is dead in line so there should be some offset when at normal ride height.
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Volvo back as my main squeeze, more boost and some interior goodies on the way.
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cheers. I have a bit of feedback from the back axle to the gear box which is mildly unpleasant, possibly due to the overly stiff rear end maybe.
Imight go for a 2 piece prop (as I have one lying about) when I go to a 5 speed, which I think I need to with 22 MPG so far...)
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1941 Wolseley Not Rod - 1956 Humber Hawk - 1957 Daimler Conquest - 1966 Buick LeSabre - 1968 Plymouth Sport Fury - 1968 Ford Galaxie - 1969 Ford Country Squire - 1969 Mercury Marquis - 1970 Morris Minor - 1970 Buick Skylark - 1970 Ford Galaxie - 1971 Ford Galaxie - 1976 Continental Mark IV - 1976 Ford Capri - 1994 Ford Fiesta
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79cord
Posted a lot
Posts: 2,615
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Interesting stuff. All I remember was that Mk3 GT / GXL had 2-piece with UJ while basic were 1 piece (I thought).
Australian 'tinas went to 1 piece after they dumped the Falcon 4.1l 6 in them & had to jack up the suspension 2" a year later because of examples that were cracking their already reinforced frt sub-frames after hitting their bump-stops trying to handle the weight! Which then resulted in bump-steer due to the ill-advised steering geometry, added to the understeer already created by the extra weight...
After that they decided to completely redesign the Australian Mk 4 frt suspension for more suspension travel & eventually lowered it again & went back to 2-piece Driveshaft on some models.
Didn't Mk 5 get variable rate rear springs & CV jointed 2-piece driveshaft by the end?
Didn't some companies cone or 'beehive' wound coils also allow a little more suspension travel by allowing coils to compress 'inside' one another (thinking of some Opel claim).
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Last Edit: Aug 10, 2007 4:31:44 GMT by 79cord
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stealthstylz
Club Retro Rides Member
Posts: 14,926
Club RR Member Number: 174
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Can you borrow some corner weight measures?
Matt
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Can you borrow some corner weight measures? I don't know anyone who owns any. corner weight ballancing the car may be a little excessive, unless you mean just to get the weight for each spring... 79Cord - all info on the Aussie 6 pots always welcome. AFAIK the crossflow Cortina had single piece prop and the SOHC had two piece.
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1941 Wolseley Not Rod - 1956 Humber Hawk - 1957 Daimler Conquest - 1966 Buick LeSabre - 1968 Plymouth Sport Fury - 1968 Ford Galaxie - 1969 Ford Country Squire - 1969 Mercury Marquis - 1970 Morris Minor - 1970 Buick Skylark - 1970 Ford Galaxie - 1971 Ford Galaxie - 1976 Continental Mark IV - 1976 Ford Capri - 1994 Ford Fiesta
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stealthstylz
Club Retro Rides Member
Posts: 14,926
Club RR Member Number: 174
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Yep I just meant get a basic weight for each corner to guesstimate the spring rates.
Matt
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Aug 10, 2007 12:02:44 GMT
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I'd go with a two piece prop unless your planning on running lots of power as it reduces unsprung weight and will give less vibration, don't forget though props can be balanced the same as wheels.
Not sure on the spring rates, what model is it?
i'll go ask on the cortina forum for you, probably the best handling standard cortina (of the 3/4 and 5 anyway) was the 2 litre sport and they were not set up that stiffly.
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Volvo back as my main squeeze, more boost and some interior goodies on the way.
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Aug 10, 2007 12:09:48 GMT
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Yep I just meant get a basic weight for each corner to guesstimate the spring rates. Matt How are you going to establish a spring rate from a corner weight?
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1974 Lancia Beta Saloon 1975 Mazda 929 Coupé 1986 Mazda 929 Wagon 1979 Mazda 929 Hardtop 1982 Fiat Argenta 2.0 iniezione elettronica 1977 Toyota Carina TA14 1989 Subaru 1800 Wagon 1982 Hyundai Pony 1200TL 2-dr 1985 Hyundai Pony 1200 GL 1986 Maserati 425 Biturbo 1992 Rover 214 SEi 5-dr 2000 Rover 45 V6 Club 1994 Peugeot 205 'Junior' Diesel 1988 Volvo 760 Turbodiesel Saloon 1992 Talbot Express Autosleeper Rambler 2003 Renault Laguna SPEARS OR REAPERS
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bstardchild
Club Retro Rides Member
Posts: 14,937
Club RR Member Number: 71
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Aug 10, 2007 12:12:41 GMT
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Yep I just meant get a basic weight for each corner to guesstimate the spring rates. Matt How are you going to establish a spring rate from a corner weight? I'm interested in that too I thought corner weight scales were used to adjust the springs to distribute the weight on the contact points (tyres) But I might be wrong
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Aug 10, 2007 12:20:40 GMT
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I presume he means by knowing the overall weight of the car and the ballance at the corners you know the distribution of the weight better and can optimise your spring choices.
Mr Toaster, I go on Buy Sell Cortina if thats the one you mean and should haveposted this there I guess.
The car was a 1600L crossflow but is now a 2.0 Pinto in it. (Its the white Mk3)
current springs are -2" but no idea of the rate on them.
rear suspension suffers fron crash on our rough orads locally which is pretty painful when turning and accelerating...
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1941 Wolseley Not Rod - 1956 Humber Hawk - 1957 Daimler Conquest - 1966 Buick LeSabre - 1968 Plymouth Sport Fury - 1968 Ford Galaxie - 1969 Ford Country Squire - 1969 Mercury Marquis - 1970 Morris Minor - 1970 Buick Skylark - 1970 Ford Galaxie - 1971 Ford Galaxie - 1976 Continental Mark IV - 1976 Ford Capri - 1994 Ford Fiesta
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Aug 10, 2007 12:40:24 GMT
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A corner weight will tell you 1% of nothing about your spring rate.
Ideally someone will have worked this out before though, there are enough cortina tinkerers out there that I'm sure someone knows at least the standard spring length and rate, once you have got this you have at least a point to work from.
The other thing you 'know' or can easily find (using jacks and tape measures), is the spring length at the ride height you want.
Then you can do some sums, for instance you could say I want spring which are 40% stiffer than normal and which will give me a ride height of X, and you'd have enough information to be able to work out the rate and free length, which is what a speing manufacturer would need to know, or what you would need to know if you were selecting from a spring catalogue or whatever.
If you want to use variable rate springs, you'd really need a graph of the rate vs. compression to be able to select the right one, not sure how 'available' such info is.
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1974 Lancia Beta Saloon 1975 Mazda 929 Coupé 1986 Mazda 929 Wagon 1979 Mazda 929 Hardtop 1982 Fiat Argenta 2.0 iniezione elettronica 1977 Toyota Carina TA14 1989 Subaru 1800 Wagon 1982 Hyundai Pony 1200TL 2-dr 1985 Hyundai Pony 1200 GL 1986 Maserati 425 Biturbo 1992 Rover 214 SEi 5-dr 2000 Rover 45 V6 Club 1994 Peugeot 205 'Junior' Diesel 1988 Volvo 760 Turbodiesel Saloon 1992 Talbot Express Autosleeper Rambler 2003 Renault Laguna SPEARS OR REAPERS
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Aug 10, 2007 12:49:23 GMT
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I had briefly thought that grabbing some progressives off a car of the same weight would be a possible until 0.0005 seconds later remembering that the geometry affects the required spring rate... meh.
odd as it may sound I'm going to try some other wheels on it instead first. adding some sidewall may introduce enough "give" to get the ride quality where I need it. I think the combo of hard spring and low profiles is too much. the tyres are easier to try out than the springs so...
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1941 Wolseley Not Rod - 1956 Humber Hawk - 1957 Daimler Conquest - 1966 Buick LeSabre - 1968 Plymouth Sport Fury - 1968 Ford Galaxie - 1969 Ford Country Squire - 1969 Mercury Marquis - 1970 Morris Minor - 1970 Buick Skylark - 1970 Ford Galaxie - 1971 Ford Galaxie - 1976 Continental Mark IV - 1976 Ford Capri - 1994 Ford Fiesta
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79cord
Posted a lot
Posts: 2,615
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Aug 10, 2007 12:50:08 GMT
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Personally I avoided the 6's for the 2-litre due to their widespread reputation for ill-handling so can't say too much more about them that isn't covered elsewhere... but did get examples built after Ford had notched the firewall & radiator supports 4" & enlarged transmission tunnel for it, so I could still move the pinto back further if advantageous, & before their ride height was raised from the 13cm ground clearance the early examples had (according to period magazine road tests) . Still tempted to keep an eye out for the (supposedly lighter gauge steel) frt subframe used on our early pre-6 (Sept '72 ?) 'tina's.
Picked up a few rough examples to play with several years ago when they were relatively common but worthless before I was sidetracked by other projects... wishing I'd shelled out for a nice one now that their numbers have diminished drastically, & I found my 'nice' one's tail has been distorted in all directions by what might have been minor damage but for the tow-bar fitted to it to spread the impact far & wide. Not helped by the fact that Australian (Sydney) Cortina build quality was notoriously bad - for example upper sill spot-welds missed target along entire length on one side !
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79cord
Posted a lot
Posts: 2,615
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Aug 10, 2007 13:53:11 GMT
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Bit of digging & found one of my favorite period Mk3 Cortina articles: Automotive Engineer November 1970 (UK)Lots of weird Cortina technical details few people would actually want to know, in case any of it is useful to you: BasicSprung wheel load kg(lb) Frt 253(558), RR 267(590) Wheel rate, bump kgf/cm(lbf/in) Frt 20(112), RR 19.75(110) Natural freq, laden, c/min Frt 68, Rr 80 Natural freq, unladen, c/min Frt 75, Rr 102 no anti-roll bar Total roll stiffness m kp/deg(lbf ft/deg) frt 33.7(244) rr 15.6 (112) 1.6 GT (SOHC) Sprung wheel load kg(lb) Frt 270(595), RR 279(615) Wheel rate, bump kgf/cm(lbf/in) Frt 20(112), RR 22.7(128) Natural freq, laden, c/min frt 66, rr 86 Natural freq, unladen, c/min frt 73, rr 100 Rate of anti-roll bar kgf/cm (lbf/in) frt only 6.85(38.4) Total roll stiffness m kp/deg(lbf ft/deg) frt 47(340 rr 17.75 (128) Other notable info: drag coefficient 0.455 torsional rigidity 784mkp/deg,5656lbf/deg bending deflection under 780kg/1720 lb= 0.65mm/0.029in ground clearance 127mm Kerb weight 1300cc 945kg/2083lb 1600cc 960kg/2115lb 1600GT 990kg/2182lb 2000GT 1000kg/2204lb I suppose I should be sharing the full article around somehow /somewhere ?? & I remembered that in Australia around '75 there was a"Rallye" pack option for the 2L that added rear anti-rollbar (though still with the jacked up ride-height they had by then), don't remember the other details of it though !
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Last Edit: Aug 10, 2007 13:58:24 GMT by 79cord
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Aug 10, 2007 13:55:15 GMT
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cheers, not sure how meaningful that is to me but might be helpful in getting the right springs...
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1941 Wolseley Not Rod - 1956 Humber Hawk - 1957 Daimler Conquest - 1966 Buick LeSabre - 1968 Plymouth Sport Fury - 1968 Ford Galaxie - 1969 Ford Country Squire - 1969 Mercury Marquis - 1970 Morris Minor - 1970 Buick Skylark - 1970 Ford Galaxie - 1971 Ford Galaxie - 1976 Continental Mark IV - 1976 Ford Capri - 1994 Ford Fiesta
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Aug 10, 2007 14:01:12 GMT
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AK, call up south yorkshire springs, chances are they will be able to tell you what was standard rate and length, they will also advise on uprated/shorter springs to suit what you want to do Very helpful and very very reasonable on price too - I was quoted under £100 for 4 Kadett coil springs any rate any length, including vat & Del and they knew what worked on them too as they supply/have supplied most of the Rally/race teams at one time or another HTH Dom
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Aug 10, 2007 14:04:18 GMT
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Cheers Dom, I'll call them up
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1941 Wolseley Not Rod - 1956 Humber Hawk - 1957 Daimler Conquest - 1966 Buick LeSabre - 1968 Plymouth Sport Fury - 1968 Ford Galaxie - 1969 Ford Country Squire - 1969 Mercury Marquis - 1970 Morris Minor - 1970 Buick Skylark - 1970 Ford Galaxie - 1971 Ford Galaxie - 1976 Continental Mark IV - 1976 Ford Capri - 1994 Ford Fiesta
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