Suspension Design - pros/cons and customisation

[david bfreesani]

Its only been SFA for 4 years now. The last year it has been off the road. But before that it ran as my daily driver. Even moved house.

My wife was driving it more than I was for nearly a year, but after my last Castor change, things got a bit bad. Scrub radius went out to the extent that the front wheels would drag when you trying to get into a parking bay.

But yes, any darn thing this high on 33s would probably be horrible as a daily drive. Amazingly, my wife likes the entire experience, besides getting up and down that 700mm high step in and out the car.

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[XJ Junkie]

That thing is a complete mess & is a threat to other road users.

Push it off a cliff, so that others may live.

[david bfreesani]

Kinda harsh....

This is why I'm fixing it, and asking for some advise. By the way, this vehicle has done some operations with the police and traffic police involved, and not once have they passed a comment even close to that.

If I had the money, I'd just drop the Sani off at Robert Hairbottle, and get him to do his magic, but I don't, and need to get it sorted the best way I know how.

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[Oppies3800]

nee, safari los tc gee probleme met spasie. Maklikste is om toy 4x4 box te gebruik met sani centre agter diff, en safari voor diff. Toy sfa 4x4 box kom ook regs uit soos safari, en centre agter soos sani

Reenen se advies aan ander persoon

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[david bfreesani]

Nou al bietjie laat vir my, ek het Safari agter diff al in en Sani diffs is al vetkoop. Safari Pampoen sit regs. Lyk of ek so 40mm te min spasie het vir standaard safari agter propshaft. Sal hopelik die naweek my TC carrier klaar kry wat twee chassis crossmembers vervang met al die brackets om die TC op te monteer. Alles hang so 70mm nou onder chassis uit maar sit amper teen die vloer. Grootste kop seer is daai safari se handrem drom wat so groot is. Protection onder alles gebou.

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[Wooky]

Whooky Ironm stock those shims / wedges. Used on SFA Hilux. As far as I knows most fitment centre as well.

Thanks Grips..... will give them a try.

[Wooky]

Not easy to get a good idea of what is going on from those pictures but here are a few things I can see:

1/ If those spring packs are from a 1 ton rear then they have had the main load assistor blades removed. This would make them fairly soft in the application you are using them in. Rear springs are designed somewhat differently so that they work both for an unloaded and loaded situation and with the main load assistor removed they are now only able to carry the weight of a lightly loaded to unloaded bakkie rear.

2/ bending the springs into a -ve arch is not good for them if they are made with a +ve curve. You should extend the bump stops to limit this. It looks like the passenger side pack is already starting to separate due to this -ve flex.

3/ your shackle angle is very flat. As it is now when the spring flexes the shackle is not really swinging to absorb the movement but rather being stretched pin to pin. This is going to give you all sorts of handling issues and a very harsh ride. The swing shackle should be almost perpendicular to the spring pack to work in a neutral manner.


Before trying to get the castor issue resolved rather get the springs correct first. Once you have that sorted and working the way you want then get to work on the alignment issues.

If it were me I would start with sorting out that shackle angle.......

[david bfreesani]

Springs are separating due to the military wrap that is causing the first two blades to bind as soon as any weight is put on them. Most of those springs capacity is derived from the binding, and not the springs natural carry capability. this is also causing the spring to want to load sideways if it is enticed to do so by road conditions. this causes the car to move from side to side instead of up an down on the springs.

Only two ways to sort the shackle angle, is to extend the mounts on the chassis forward, or install new shorter springs. Not sure I will be able to keep my spring chassis mounts as they are now if I do that. I don't want to be extending the chassis any further than I have already. So shorter new springs are the way to go.

[Wooky]

So shorter new springs are the way to go.

Sounds like the whole spring and shackle setup in the front is fighting itself.
A shorter, custom made spring pack is quite possibly a better starting point in that case.

[david bfreesani]

I'll have to get some measurements as to what I need. Then get a quote to build them. I'm just very worried about custom stuff like this that you can't just run down to a spares shop or scrap yard and get them over the counter. This was one of the reasons behind the spring pack I used in the first place. Then to find that the standard one tonner spring pack could not carry the front end of the Sani because of that big diesel lump under the bonnet. And yes, I tested with and without that bottom load plate. Only difference I got with the load plate in place, was that I had no compression capability on the suspension as the spring pack was sitting dead straight on the level. So with no upward travel, I removed the load plate. I think I actually need another blade, which would mean I have added two blades to the standard pack. Not sure the shorter standard Safari spring pack would carry the Sani either. Maybe Reenen can confirm if any of his Safari/Patrols has a 2.7td or QD32 engine in it and what it does on the standard leafs. I know the standard Safari pack is about 70-100mm shorter if memory serves.

Now we enter territory where I could start agreeing with XJ Junky. That D21 chassis was not designed to carry the weight at the points where I have the springs attached, let alone over an extension out the front of the chassis that has been arc welded on. Theory puts each spring perch/shackle needing to support 400kg unloaded dead weight before driving forces get pushed into the equation. Stand the Sani on it's nose down a 30Deg hill, and forces start getting hectic.

[Wooky]

Ultimately yes you could well go through all this effort and end up with having to brace the whole front of the chassis.

A custom spring pack would be the way to go. You give the details to the spring maker and he makes a spring pack to your requirements.
I have done this in the past (not on the SJ which I bought with OME fitted) and had good results at a reasonable price.
Also removes some of the guess work on one component in the system.

I think I used these guys before (was quite a while ago so could be wrong) http://springcentre.co.za/Pages/Contact-Us.asp

[david bfreesani]

Dunno if I even want to see the quote in my current financial state .Just adding that extra blade to the original spring pack cost me over a grand 4 years ago.

[XJ Junkie]

It’ll be cheaper to buy another modded SA’d vehicle

[david bfreesani]

It’ll be cheaper to buy another modded SA’d vehicle

Please post links to these vehicles in the 10k to15k range you refer to here. Keep in mind this will also be my daily driver.

[Reenen]