Z320 Posted June 10, 2023 Report Share Posted June 10, 2023 (edited) On 6/9/2023 at 11:03 AM, BaulyCars said: A short spring calculation? Original spring is about 260 mm long, in the car 170 mm, compresion 90 mm, load about 500 kg, spring rate 500 kg/ 9 cm = 55,55 kg/cm (310 lb/in) The spring above is 225 (beginning) / 475 (strong part) lb/in, the soft part of it is 1/ (1/225 - 1/475) = 427 lp/in. 427 "+" 475 together 225 Check with the formular of springs in a row: 1/225 = 1/427 + 1/475 Assuming the soft part is not fully compressed with the car on the road (this is what you want!) the lenght fitted in a TR4A-6 is: 260 mm - 500 kg / 0,454 kg/lb / 225 lb/in = 260 mm - 4.9" = 135 mm (not at all 170 mm) 4.9 " is 2.58" on the softer part (fully compressed or not?) + 2.32" on the stronger part. Very likely this spring doesn't fit at all on a TR. Ciao, Marco Edited June 10, 2023 by Z320 Quote Link to post Share on other sites
BaulyCars Posted June 10, 2023 Author Report Share Posted June 10, 2023 Nice work, Marco, this is great, So that spring would drop to a 135mm installed length, versus the 170mm of the original spring, so the car would be lowered by 45mm from original? That seems like an ideal rideheight drop, with a softer spring (my car dropped 50mm with 650lb springs). I'm probably missing something... Quote Link to post Share on other sites
Z320 Posted June 10, 2023 Report Share Posted June 10, 2023 Yes but no, 45 mm on the spring is 90 mm on the wheel arch. You will get a lovely low rider Quote Link to post Share on other sites
BaulyCars Posted June 10, 2023 Author Report Share Posted June 10, 2023 might look good! OK, so progressive springs don't work either. What did you think of my lower spring pan idea, I'd appreciate your thoughts on that. Nice long spring, but lowered rideheight (the 'unicorn' of set-ups....) Quote Link to post Share on other sites
Z320 Posted June 10, 2023 Report Share Posted June 10, 2023 I told you most what I did at Juni 3rd, I did not lower or modify the spring pan and never considered what are the consequences of that Ciao, Marco Quote Link to post Share on other sites
Malbaby Posted June 11, 2023 Report Share Posted June 11, 2023 (edited) 14 hours ago, BaulyCars said: might look good! OK, so progressive springs don't work either. What did you think of my lower spring pan idea, I'd appreciate your thoughts on that. Nice long spring, but lowered rideheight (the 'unicorn' of set-ups....) I think that correctly made progressive springs would work very well providing the internal diameter is adequate. From your pic the "progressive" spring appears to be wound in two distinctive pitches...ie..hard and soft sections rather than a gradual transition from soft to hard. The cost of making a true progressive spring is a question that only the manufacturer can answer. And would they have a computer program for the design?? A lowered spring pan on a TR4A/TR6 would have a minimal effect...Different story with a TR4 that has a different design shock/spring tower that could accomodate coilovers. Marco's idea of lowering the lower shock absorber attachment to increase the choice of suitable shocks is a good one. Lowering our cars is problematic, as adequate ground clearance to the front cross member requires consideration. Unfortunately no one makes a "dropped" spindle [the ideal solution] for our TR's. Edited June 11, 2023 by Malbaby Quote Link to post Share on other sites
Z320 Posted June 11, 2023 Report Share Posted June 11, 2023 (edited) btw the spring rate of your new front springs from post #1 should be 500 kg / 0.454 lb/kg / (204 mm - (170 mm - 45/2 mm) / 25.4 mm/in = 495 lb/in Edited June 11, 2023 by Z320 Quote Link to post Share on other sites
BaulyCars Posted June 11, 2023 Author Report Share Posted June 11, 2023 1 hour ago, Z320 said: btw the spring rate of your new front springs from post #1 should be 500 kg / 0.454 lb/kg / (204 mm - (170 mm - 45/2 mm) / 25.4 mm/in = 495 lb/in Thanks, Marco, that's sounds better than the 650 lb/in quoted for the spring Quote Link to post Share on other sites
BaulyCars Posted June 11, 2023 Author Report Share Posted June 11, 2023 6 hours ago, Malbaby said: I think that correctly made progressive springs would work very well providing the internal diameter is adequate. From your pic the "progressive" spring appears to be wound in two distinctive pitches...ie..hard and soft sections rather than a gradual transition from soft to hard. The cost of making a true progressive spring is a question that only the manufacturer can answer. And would they have a computer program for the design?? A lowered spring pan on a TR4A/TR6 would have a minimal effect...Different story with a TR4 that has a different design shock/spring tower that could accomodate coilovers. Marco's idea of lowering the lower shock absorber attachment to increase the choice of suitable shocks is a good one. Lowering our cars is problematic, as adequate ground clearance to the front cross member requires consideration. Unfortunately no one makes a "dropped" spindle [the ideal solution] for our TR's. I saw somewhere a drop spindle for a GT6 that someone cut and re-welded to make a drop-spindle (I think by Canley Classic, not sure). Quite popular on classic muscle cars and lots of availability (Wilwood etc). Complex to figure out geometrically to do a TR version? Quote Link to post Share on other sites
dblenk Posted June 17, 2023 Report Share Posted June 17, 2023 Hi not quite as per the thread but did the yanks have a highier ride height than the uk set up cheers david Quote Link to post Share on other sites
Malbaby Posted June 17, 2023 Report Share Posted June 17, 2023 The Americans have their cars higher so that they can "Keep their big wheels turning for proud mary" Quote Link to post Share on other sites
dblenk Posted June 19, 2023 Report Share Posted June 19, 2023 So std springs will bring it back to the UK look i checked moss USA but no spec length for the springs any friends o er the water confirm ??? david Quote Link to post Share on other sites
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