I thought I'd start a new thread on this subject to see what advise is out there!
On my trials Chummy (the one on which I keep bending the axle tubes!) the rear springs appear to be in good condition, but the deflection on trials use is so great that the axle hits the bodywork and both inner wings are now seriously reshaped. Can the springs be re-tempered for greater resistance and if so to what poundage? Are there any charts published anywhere to show the poundages originally used for the different models? I am told that maybe I could use Ruby springs which are stronger.
All suggestions welcome please.

Location: West Sussex

You won't change the spring rate by retempering. The things that affect rate are the dimensions and number of leaves.

Ruby springs are nearly flat, too. You may need to re-camber them.

Location: Richmond, Texas

Re-Tempering is a waste of time and money in my experience,within a few trials they were worse than before.
Much better to buy a new set from Jones Springs with the set you require.I chose the van settings.
Andy

Ok, thanks Andy - I'll try them in the morning. How do the van springs differ to the standard Chummy ones?
Ian Dunford has 7 leaf Chummy ones that he says I should use!

Location: West Sussex

If you look at page 80 of the 750 companion book you will see the camber dimensions,the van spec adds 1 inch to standard spec.
Its a bit of a struggle to fit them
Fit new bushes and pins also trial fit to axle, before fitting spring to chassis.
Leave everything loose until both sides are assembled then tighten.
Re build clean and adjust dampers at the same time.
Then you will be ready for the Exmoor trial.
Andy.

We have similar trials Chummy's Bob and mine's been going since 2007 with this body. When I fitted the new body in 2007 I had a pair of the springs you refer to from Ian and, to date, they've been fine and the rear axle hitting the underside is something that happens very rarely - usually when landing from a height!! Malcolm will confirm that whilst having the front wheels in the air is common, if the rear wheels are in the air also then the landing hurts our ageing backs so it's something we try to avoid.



Steve

Location: North Yorkshire

Just a thought Bob, when fitting springs lubricate well with gear oil, then wrap in Denso tape, the wrap again with cling fllm ( cut to about 2" wide). do this about every 5 years and the springs will see you out.

Location: North East

That's all most helpful, thank you everybody. I had not seen the chart in the Companion before. I will talk again to both suppliers tomorrow and see what I can get. I am entered for the Exmoor, but have the 750 Club Cold Turkey to do before that I hope.
As well as the Denso tape, what about the heat shrink method - or will that make them too stiff?
Steve - I have the same problem with my back, so do sympathise, but sadly my lack of driving skills means that I only have one driving technique - which is foot hard down, so yes, the car does suffer greatly!!
Herbert would turn in his grave if he only knew?

Location: West Sussex

Bob - To you and others who've found the Companion article to be new - note carefully that there's a misprint. We've tried over a long period to get the mistake highlighted. The camber on the rears for the standard models should read 3" not 8". Ask around your fellow trials competitors for any variation desirable for your trials Chummy. Good Luck, Cheers, Bill in Oz

For what its worth Bob I get my Cup Model springs set to 9.5" rear camber.
If the springs are set and tempered correctly then they should not let themselves back down again.

Location: New Forest

Ok - just to let you all know I've ordered a set of heavy duty, 7 leaf, 6.5" camber springs from Ian Dunford. That is 1" more camber than I have now and with the stronger springs I think will do the job. I'm not brave enough to go for a 9" camber, that does sound extreme, it must be difficult to drive in a straight line down the road?
If I've made a wrong call I'll let you know at the end of the season!
Once again, thanks everybody for your very useful comments, great Forum this isn't it?
Bob.

Location: West Sussex

Location: New Forest

I'm impressed Stuart! I am pleased to be corrected and withdraw my comment.
Bob.

Location: West Sussex

Bob, i have Ian's chummy springs on the back of the saloon, assisted by a pair of Nobbys. They have proved very capable of handling 4 up A7 trialling! Highly recommended. W

Thanks for that Winston, very encouraging! I've certainly seen your saloon in action and know that you take no prisoners!
I was going to remove my Nobbys, being concerned after bending the axle, but perhaps I'll retain them as the axle is being reinforced anyway.
Springs arrived today and they certainly look much beefier than my old set, so it's fingers crossed!

Location: West Sussex

Thinking about it Bob you won't need as much as 9.5" camber as you do not have the bottom of a tail to contend with on a Chummy like I do on the Cup Model.

Location: New Forest