Leaf spring tuning?

linearaudio · Post by **linearaudio** » Wed Oct 28, 2009 8:59 pm

Any tips, sensible or radical, on how to improve the ride quality of the Traveller rear springs without abandoning the basic idea of having leaf springs? I note parabolics and composites are around for some applications, and wondered if any thoughts had been put in either of those directions, by a well known Moggy modifier maybe?

At present I am running on sleeved down van springs as I was unable to get 7 leaf springs with the correct initial "set" (ride height), but these are proving far too inflexible. I am toying with dismantling, and making a hybrid set up and would be interested in others' ideas!
And yes I know about the "unfit for purpose, send them back" argument, but having tried 4 different sets previously don't hold out much hope of finding better!

Post by **bmcecosse** » Wed Oct 28, 2009 9:16 pm

Remove one or more of the leaves from the van set ?

linearaudio · Post by **linearaudio** » Wed Oct 28, 2009 9:35 pm

bmcecosse wrote:Remove one or more of the leaves from the van set ?

Yes , thought about that, but that would give an uneven length gap between leaves. ie: there is a 3" length difference at each leaf, if I take one out then I will have one "step" of 6". This may give an unwanted bending stress at that point, or am I being over-critical?

Post by **bmcecosse** » Wed Oct 28, 2009 9:40 pm

Well - it's a point - but I would take out the shortest and try that ?

linearaudio · Post by **linearaudio** » Wed Oct 28, 2009 9:50 pm

bmcecosse wrote:Well - it's a point - but I would take out the shortest and try that ?

Aaah!! But that is the point of maximum stress! Less stress as you get nearer the "eyes". See my worries?

Post by **bmcecosse** » Wed Oct 28, 2009 9:54 pm

Nope -don't see that - the whole spring assy is taking the load. Just take out the bottom (shortest) leaf and try it! Have you compared the MGB 'parabolic' spring to a Minor spring - may not be that different.

linearaudio · Post by **linearaudio** » Wed Oct 28, 2009 10:18 pm

bmcecosse wrote:Nope -don't see that - the whole spring assy is taking the load. Just take out the bottom (shortest) leaf and try it! Have you compared the MGB 'parabolic' spring to a Minor spring - may not be that different.

Yes, the width is a potential problem, as possibly the extra travel which may occur- and.........

They taper towards the ends!! Due to the forces being greater in the centre section!!!! Think about it, beam deflection basics!

Post by **bmcecosse** » Wed Oct 28, 2009 10:27 pm

Yes - and you presumably want the 'beam' to deflect a bit more easily - to soften the ride ?

Post by **Bazzalucas** » Thu Oct 29, 2009 1:37 am

Do MGB springs fit? I have an extra set...

Post by **bmcecosse** » Thu Oct 29, 2009 9:01 am

That's what we we want to know! Are they in any way similar ?

linearaudio · Post by **linearaudio** » Thu Oct 29, 2009 9:28 am

I have an MGB in my front garden- yes- remarkably similar length, but wider by a bit, as are Ital estate springs. I mention these as the Ital in my local yard looks to have parabolic springs? From memory it only has 3 leaves, and they touch at the ends. Was the Ital really that advanced?
The standard MGB ones would be no benefit, having the same conventional make-up as the Moggy ones, but the thought of adapting a set of MGB composite springs is appealing! They are rated at 135lb/ft, any ideas what the Traveller springs are rated at?

Post by **Innovator** » Thu Oct 29, 2009 4:50 pm

Try reducing the friction between the springs by either oil or grease or dry bearing material. It was (still is??) a common modification on USA Hot Rods (or should that be cold rods if they are still using leaf springs??!!). They put teflon buttons between the leaves.

Post by **minor_hickup** » Thu Oct 29, 2009 9:16 pm

The problem is that you're using 8 leaf springs! 7 leaf springs are more than hard enough for a traveller. You will not get a decent ride quality as the spring rate is far too high and there's more stiction due to the extra leaf.

I'm not aware of any problem with Traveller leaf springs, and if you've tried 4 sets then it suggests the problem is not with the springs but your vehicle, or your expectations of where it should sit. I've just fitted the rear suspension up to my project Morris with lowering blocks, I really hope the springs do 'give' a little after a while as it still sits rather high.

linearaudio · Post by **linearaudio** » Thu Oct 29, 2009 9:47 pm

The supplier admitted that the Traveller springs had a shallower height set on them than the saloon or van springs. We exhaustively checked all aspects of the geometry, the car sat with less than 1" clearance between chassis and bumpstop unloaded, and sank noticeably with 8 stone passenger in back, leaving about 1/2" clearance. Unsurprisingly the car spent most of its time bottoming out! That does not signify springs which are "more than adequate" to me!
However, the use of 8 leaf springs is too stiff, hence my thoughts of a hybrid set.
Teflon buttons sounds a good idea, and would permit each leaf to work more as an independant unit rather than grinding against the one on either side. Sourcing could be tricky on this side of the water, though?

Post by **alanworland** » Thu Oct 29, 2009 10:03 pm

I am sure I have had in the past a small sheet of PTFE and guess it was only about 0.030 thick and ideal for fitting in between leaves? must be available.
See my post on rear bump stops and springs.

Post by **bmcecosse** » Thu Oct 29, 2009 10:03 pm

One of the (few) advantages of leaf springs is that they are 'self-damping' to an extent - due to the friction as the leaves slide against each other. take away the friction and you will lose that. It IS the fact that these springs are just higher rated - so taking out leaves is the only way!

Post by **minor_hickup** » Thu Oct 29, 2009 10:16 pm

linearaudio wrote:The supplier admitted that the Traveller springs had a shallower height set on them than the saloon or van springs. We exhaustively checked all aspects of the geometry, the car sat with less than 1" clearance between chassis and bumpstop unloaded, and sank noticeably with 8 stone passenger in back, leaving about 1/2" clearance. Unsurprisingly the car spent most of its time bottoming out! That does not signify springs which are "more than adequate" to me!
However, the use of 8 leaf springs is too stiff, hence my thoughts of a hybrid set.
Teflon buttons sounds a good idea, and would permit each leaf to work more as an independant unit rather than grinding against the one on either side. Sourcing could be tricky on this side of the water, though?

The distance between the bump stop and the body is the least relavant as the bump stop is a piece of rubber and subject to change, the mounting positions are what is important. I don't think I've ever seen a minor with much more than an inch between the bump stop and body with new springs or not, once they sag the gap becomes almost non existant.

I get the feeling such a large bump stop with a large taper was used as it was expected to touch the boot floor when the car was loaded, perhaps to stop it sitting down too far. Perhaps switching back to the 7 leaf springs and cutting down the bump stops would be more satisfactory, reshaping them to a taper of course.

As for 'self damping', the problem is this stiction makes the ride terrible as it often takes so much energy before the springs start to move relative to how much it takes to compress them, a bit like friction dampers. Although I see your point, with 30+ year old lever arms the only real damping may be from the springs themselves! As for my springs I've greased and lightly wrapped them in denso tape to help stop friction between the leaves and leave damping to a set of vertical telescopics!

Post by **bmcecosse** » Thu Oct 29, 2009 10:22 pm

Yes - mine are cut down by approx 1.5" - there is plenty of over-travel in the standard dampers and their linkages to allow this.
This may not be the case if after market tele dampers have been fitted! My Trav would overwise be more or less sitting on the normal bump stops - I carry a box of spares with me at all times!

Post by **RogerRust** » Fri Oct 30, 2009 7:02 am

In my simple mind I think I'd fit some new 7 leaf traveller springs and adjust the ride height by fitting longer shackles. Is that too easy?

Post by **Declan_Burns** » Fri Oct 30, 2009 7:30 am

Why not make up adjustable shackles? Should be quite easy to do with threaded rod. Just an idea!

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Leaf spring tuning?

Leaf spring tuning?

Ride height