Leaf spring tuning?

linearaudio · Post by **linearaudio** » Fri Oct 30, 2009 8:47 am

The damping effect of the leaves-stiction, not desirable, in my view, and very variable depending on how much the springs have moved recently, whether they are bone dry or soaking wet etc. My ideal would be a set of springs that just spring, with the tele dampers which are going in as soon as possible, partly as one of the old lever arms is worn badly on its shaft and the other persists in clipping the exhaust (poor excuse).
My hesitation at the simple cure of cutting bumpstops down is 2 fold. First- why the need, if the vehicle is as per design it should have 2" clearance? Secondly, the springs showed an alarming tendency to "progressively settle", ie after 10,000 miles/ 10 months on the first replacement set they had given up all pretence of holding the car off the bumpstops, and I was concerned at what point they would fail if I allowed them ever more movement. The 2" extended shackles did the trick with the last set, but noticeably increased the lateral movement of the axle!
As regards bumpstops, while the originals were softish, the replacement ones are far less compliant, and would not act as spring assisters very well!
YES I WILL take a leaf out of the 8 leaf set! But the purpose of this thread really was to investigate thoughts on other options- teflon buttons/ ptfe sheet sounds a good one!
Thanks for all the input so far!

Post by **mike.perry** » Fri Oct 30, 2009 9:44 am

Maybe I am lucky. Last year I bought a pair of Traveller springs from that well known establishment in Birmingham to replace a broken spring. Having replaced the damaged spring there appears to be no difference in the ride height or clearances between the old and new springs. One day I will get around to replacing the other spring.

Post by **bmcecosse** » Fri Oct 30, 2009 10:13 am

Yes - I think that's the point - the new leaf springs are not correctly cambered to raise the car back to the 'new' setting. And settling even lower in only 10,000 miles isn't right either! If you want' friction-less' springing you will need to go to coil springs - a compact version of our very own torsion bar springs on the front!

linearaudio · Post by **linearaudio** » Fri Oct 30, 2009 6:59 pm

Or composite leaf springs a la MGB? Far less mods than a coil set!

Post by **bmcecosse** » Fri Oct 30, 2009 9:11 pm

I did suggest the MGB 'parabolic' spring ages ago - is that not the 'composite' spring ? It is I think single leaf!

linearaudio · Post by **linearaudio** » Fri Oct 30, 2009 10:21 pm

No- the parabolics are rolled taper steel leaf, two leaf as a safety measure in case one snaps, around £200. The composites are another league entirely, sort of like tent poles are made, with the eye plates made of steel and rivetted to the ends, price and availability seems a little vague, seem to come ( like most good things

) from the good ole US of A.

Post by **bmcecosse** » Fri Oct 30, 2009 10:31 pm

Ooooooooooohh.

Expensive! http://www.liteflexllc.com/
It suggests they have an outlet in England - Woodcote, Haytons Bent, Ludlow, Shropshire, SY8 2AY

Post by **MarkyB** » Sat Oct 31, 2009 8:22 am

A quarter of the weight of steel is significant.
Do the springs count as sprung or unsprung weight?

I couldn't find any mention of prices on that site which does suggest expensive.

Looks like a UK Range Rover on one of the PDFs.

Post by **alanworland** » Sat Oct 31, 2009 5:34 pm

The fixed end counts as 'unsprung' and the moving end 'sprung'

Post by **Peetee** » Sat Oct 31, 2009 7:03 pm

I would speculate that new springs do not have the right spring rate as they seem to flatten in a very short time. Within a few days of fitting mine, I noticed they had become too long. The shackle plates were angled well back and the rear scroll was touching the flange on the rear floor rail.

linearaudio · Post by **linearaudio** » Sat Oct 31, 2009 8:35 pm

Just what I had, and at that point there are some horrendous forces building up as the rear scroll tries to bury itself into the chassis! The penultimate traveller set I had did seem to level out after a few weeks, but as I said, then needed 2" shackle extensions to maintain correct ride height! The final traveller set sank as I lowered the car onto them

, hence my doubts that they are "well up to the job"!

Post by **Peetee** » Sun Nov 01, 2009 12:14 am

So if this is a common fault what can the 'common man' do about it?
To be honest I wouldn't have noticed the problem if it wasn't for the creaking from the rear.

Post by **MarkyB** » Sun Nov 01, 2009 7:49 am

Is the spring rate a function of the way the steel has been tempered?

Cart springs were originally blacksmith made and I understand a blacksmith can reset them and replace leaves if necessary.

It sounds like replacement springs aren't getting tempered at all.
This might be because a third party has been commissioned to make them from a pattern.
They will produce something thatlooks exactly the same but wont work properly or last.
A bit like a Chinese screwdriver.

Post by **bmcecosse** » Sun Nov 01, 2009 10:54 am

Yes - it should be possible for the individual leaves to be re-set - as long as they haven't worn too much, they should be fine !
http://www.industrialsprings.com.au/make_le.htm

Post by **MarkyB** » Sun Nov 01, 2009 4:35 pm

I see,

This is achieved by re-heating the spring to a pre-determined temperature that produces a finished hardness that will resist sagging, while being ductile enough to avoid breakage. This process is known as ‘tempering’.

I suspect this stage is being missed or not done properly on replacement springs.

Here is someone a bit closer to home than Australia: http://www.jones-springs.co.uk/home.htm

Might be worth giving them a ring and explaining what has happened.

Post by **bmcecosse** » Sun Nov 01, 2009 5:06 pm

Yes - it's very likely the 'tempering' is not correct.

linearaudio · Post by **linearaudio** » Sun Nov 01, 2009 5:21 pm

MarkyB wrote:I see,
This is achieved by re-heating the spring to a pre-determined temperature that produces a finished hardness that will resist sagging, while being ductile enough to avoid breakage. This process is known as ‘tempering’.
I suspect this stage is being missed or not done properly on replacement springs.

Here is someone a bit closer to home than Australia: http://www.jones-springs.co.uk/home.htm

Might be worth giving them a ring and explaining what has happened.

Strangely enough, they were my next avenue of research, going to speak with them this week, more with regard to the feasibility of rolling a set(s?) of parabolics!