[TR] Spitfire rear swing spring - current replacement spring w/ thicker leaves - ride/handling?

John Macartney john.macartney at ukpips.org.uk
Mon Jan 16 04:20:40 MST 2017


Aribert

 

Fully understand what you’re seeking to achieve but I feel that seeking the views of others could be fairly subjective. What suits different people may not suit you. Equally, you’re getting into some fairly technical stuff here in which swapping leaves could/will significantly alter the ‘periodicity’ harmonics of the spring and not necessarily to your liking. After all, you won’t be able to make a decision about whether your mods are the way you want them until the car is all bolted up together and you can drive it. I stand to be corrected here but my memory tells me the GT6 and Spitfire swing springs *were* different and as you’re effectively driving a soft top GT6, your new spring as it stands could well be too soft.

If I was in your position, I think I’d install the spring as it is and without modification, but to fit adjustable dampers. If what you have bought is actually a Spitfire spring rather than a GT6 version, the incremental power going down the driveline will increase the amount of rear wheel ‘squat’ anyway. So wish I still had all my tech spec books to give a more informed opinion but I lost them many years ago.

 

Jonmac

 

From: Triumphs [mailto:triumphs-bounces at autox.team.net] On Behalf Of aribert neumann
Sent: 16 January 2017 03:33
To: triumphs at autox.team.net
Subject: [TR] Spitfire rear swing spring - current replacement spring w/ thicker leaves - ride/handling?

 

Greetings all:

The stock '78 Spitfire swing spring had a 0.25 thick eye and loop leaves (these are the two full length leaves).  The new replacement spring sourced from TRF  has a 0.315 (8mm)  thick material for the eye  leaf and a whopping 0.402 or 10.2mm thick stock for the loop leaf.  The .315 eye leaf is the fixed leaf - a material increase would stiffen the spring asm w/o affecting roll stiffness - in my opinion a good thing since the stock Spit spring yields to much/ too soon in use.  The .402 loop leaf is the first pivoting leaf.  I would expect that this leaf will significantly affect roll stiffness.  

For any of you that have installed a new Spitfire rear swing spring, how do you like the ride / handling?  Do you like it more or less that the original spring?  If you like it less, would you have been happy w/ a stiffness somewhere in between the stock original spring and the new replacement?   I ask all these questions because I am suddenly concerned that the rear end of the car will be too stiff and handling will be different and that I might not like it.  I am seriously considering to dismantle my new spring and replace the 0.402 inch thick loop leaf w/ the 0.25 inch thick original loop leaf (keeping the thicker eye leaf - so the net result would be a slightly stiffer than stock '78 swing spring).  My car is a Spit bodied '71 GT6 and I did **not** like the handling of the car w/ the original rigid leaf spring so I upgraded to the '78 swing spring when I did the body swap in the early '90s.   I need to make a decision as to whether I should use the spring asm as is or make a custom spring my using a part from my existing spring by about midday tomorrow.   

The reason for installing a new rear swing spring is that my existing one had the 3rd and 4th (counting from the bottom up) leaves fractured at the pivot bump.   TIA for any responses. 



 



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