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Go Back   Madabout Kitcars Forum > Mad Build Area > Sammio Builds and discussions

Sammio Builds and discussions Sammio bodied car builds and specials

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  #1  
Old 2nd November 2016, 19:25
Car photographer Car photographer is offline
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Default Softening triumph suspension - how?

Hi everyone,
Although I don't have a sammio or miglia I figured you guys might be the best to ask this question to as your kits are triumph based and so some of you may have come across this problem.

Basically my car(a Fiorano corsa spyder ) is now much lighter than the donor spitfire used to be because of the fiberglass body - and the suspension now seems very hard and hardly moves at all - resulting in a very hard bumpy ride quality which translates into my wheel arch supports snapping very regularly.

So im in the process of having some more arch supports made but I figured that if I can soften the ride of the car it may reduce the risk of it happening again in the future.

So my question is, does anyone know the best way to do this and soften the ride / suspension on a mk4 1971 spitfire ?
Thanks

Last edited by Car photographer; 2nd November 2016 at 19:27..
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  #2  
Old 2nd November 2016, 20:49
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Have a look through the Mister Towed on the road thread, as he has made a lot of changes to his suspension set up over the years.

He always includes good descriptions of what he did and the impact it had.

Good luck, Paul.

Last edited by Paul L; 2nd November 2016 at 21:31.. Reason: Typo
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  #3  
Old 3rd November 2016, 06:28
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Hi CP, both front and rear are quite simple to soften for a lighter car than Triumph intended.

At the front on a '71 mkIV, you're likely to have either 180lb or 'uprated' 330lb springs. Assuming you still have the Spitfire four pot motor and haven't gone with a six, change those for mk I or II 150lb springs.

They're a straight swap and work well with standard dampers. You can fit ride/height adjustable shocks to vary the ride height, but don't turn the rebound setting up too high or you'll be back to rattling your fillings out.

At the back, the transverse leaf spring is modular and easy to tinker with. Once removed, take out the central stabilising stud and the top three leaves can just be lifted off and the remaining spring stack bolted back onto the diff with either threaded rod to replace the diff studs or a suitable spacer added to the top of the stack under the clamping plate to make up for the missing three leaves (don't forget to put the central stabilising stud back in btw).

That would give you a softer ride, but I found that it was still too stiff for my liking. The next stage is to take the securing bolts out of the inverted 'U' shaped clamps that hold the next three leaves together and remove the middle leaf from that stack. Again, standard shocks are fine as they're effectively mildly 'uprated' on a much lighter car.

If you have a 'swing spring' setup (the top clamping plate has an inverted 'V' shaped notch in the middle) I'm sure that these mods can be adapted to suit, and I'll be trying that myself on my next project.

Oh, and you'll also need to fit the 7/8" front anti roll bar to compensate for the softer back end if you haven't already got one on your '71.

It's also worth making sure that the lower front 'A' arms are parallel to the ground and dialling in some toe-in at the rear and toe-out at the front for best results.

For my 680kg car those mods vastly improved the ride and handling. With the too stiff setup the front and rear wheels would continuously hop off the road surface making the car feel very skittish indeed. With the softer ride the grip and feel through the steering and seat of the pants has been transformed, and I can now drive it across our bumpy fen roads at speed with complete confidence.

As Paul says there are some pictures buried in my build thread and I'm also happy to answer any questions you might have.

Good luck!
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Old 3rd November 2016, 08:38
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Thanks, that helps, I have some lowered front springs that I was going to fit to my old spitfire - maybe those might help too,
I also ordered some Avo adjustable shocks so hopefully they will give me the adjustment I need

Thanks again
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  #5  
Old 22nd November 2016, 17:30
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Ok, so today we finished doing the suspension work - we fitted avo ajustable dampers all round, lower (330) springs on the front and took one large leaf out of the rear leaf spring.

it is a much better, softer ride now, the front stance is nice and low - but the camber on the rear wheels is a bit extreme (top image was taken before the rear spring was altered)
- not sure how I can correct this - other than getting a slightly longer leaf spring made up specially ..... any ideas?

[IMG]DSC_0071 by paul ward, on Flickr[/IMG]

DSC_0016 by paul ward, on Flickr
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  #6  
Old 23rd November 2016, 06:27
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Nice looking car and I love the colour, very period.

The camber on the rear wheels looks to be down to the drive shafts. Late Mk IV Spitfires (from '72?) and all 1500's used longer drive shafts than Heralds, Vitesses and early Spitfires to introduce negative camber and improve the handling.

You can tell which type you have by looking at the tie bars - if their ends are at 90 degrees to the shaft you'll have short shafts, if they're angled slightly you'll have long ones (see discussions in the links below). The body brackets are also slightly different. From the look of the back of your car I'd say you have the long ones.

To change to short shafts you'll need: a pair of shafts from an early Spit, Herald or Vitesse; a pair of straight tie rods; and a pair of early body mounting brackets to attach the tie rods to the body. That lot will just bolt up to your existing spring and reduce the amount of negative camber. You should also be able to sell your long shafts, tie rods and brackets for similar money to what you pay for the short ones.

If you already have the short shafts fitted then either you've got a ton of lead in the body at the back or your leaf spring is worn out. They're cheap enough to replace though -

http://www.ebay.co.uk/itm/REAR-LEAF-...IAAOSwExJXofAr

http://clubtriumph.eu/cgi-bin/forum1...?m-1308488838/

http://auskellian.com/paul/links_fil...hancements.htm
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Old 23rd November 2016, 06:55
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What did you alter on the rear end, it looks like you have both excessive camber but also toe in.
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Old 23rd November 2016, 11:18
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cheers-
that was how the car came unfortunatly - it was half built.
- I'll look into the short or long shafts

but couldn't I solve this by having a slightly longer spring made up?

seems like all the other options are lots of hassle
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  #9  
Old 23rd November 2016, 16:28
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Not sure where you'd have a longer leaf spring stack made up, but adjustable vertical links are available from the likes of Wolfitt racing -

http://www.wolfitt.com/wolfitt_produ...htm#Adjustable rear vertical link kit

It would be a lot simpler and cheaper just to change the drive shafts though.

Oh, have you checked to see if there's a lowering block fitted? If there is then taking that out might correct the issue.
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Old 23rd November 2016, 18:25
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Okay, here we go, I just happened to have examples of both long and short shafts amongst my collection of Triumph parts -







Late Spitfire on the left, Herald on the right. Both are standing on their wheel studs and their drive flanges are level (common part to both, so the same length).

There's about 35mm difference between them, so 70mm across a pair at the wheel centres. That will be a lot more at the road surface. If you measure the length of the vertical links from the wheel centre, add the radius of the wheel and tyre then do some simple geometry jiggery-pokery, you should be able to calculate the difference between the two types of shaft at the bottom of the wheels.

I'm guessing that your car has the longer shafts fitted and, assuming you know your way around a set of spanners, the simplest way by far to pull the wheels back in at the bottom would be to swap them for short ones.
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Old 23rd November 2016, 21:38
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Cool, thanks for that info, this could be the answer!!
So am I right in thinking that if I went for the shorter hubs then I'd probably need the adjustable radius arms too?
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Old 24th November 2016, 05:35
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trailing arms need to be longer spring to soft.....
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Old 24th November 2016, 06:14
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Quote:
Originally Posted by Car photographer View Post
Cool, thanks for that info, this could be the answer!!
So am I right in thinking that if I went for the shorter hubs then I'd probably need the adjustable radius arms too?
Not necessarily adjustable radius arms, just the right ones for the shafts that you have fitted.

From my reading of the available information it appears that there are three types of standard radius arm:

'I' shaped to match short Spitfire shafts;

Italic 'I' shaped to match long Spitfire shafts;

Bent 'I' shaped for Herald and Vitesse.

The adjustable ones from Wolfitt (and other suppliers) do look cool though and would make setting the rear toe-in much easier. They're not overly expensive either.
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Old 24th November 2016, 06:35
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Just an early morning thought and I may have overlooked something, but......if the problem is the result of mismatched driveshafts and spring, it will be cheaper and easier to swap to the correct spring.
I have Herald (longer) driveshafts, a later Spitfire swing spring and 1" lowering block, and camber is bang on.
Can you get a pic of the rear spring, particularly where it mounts on the diff.
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Old 24th November 2016, 13:19
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here's the spring - and the leaf we took out but unfortunatly I didn't get a shot of the diff before we re fitted it.
DSC_0011 by paul ward, on Flickr
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Old 24th November 2016, 13:22
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Your advice has been very helpful everyone - thanks

at the moment there seems like a few possible options -

1. changing the half shaft length to the shorter ones.

2. Fitting the adjustable vertical link mod.

3. getting a bespoke leaf spring made up to the correct length and weight ratio needed to adjust the camber.

The vertical link mod might be the cheapest, but would require welding onto the link and that could be difficult to get done properly,
the half shafts are going to be hassle because you'd need to pull both hubs and rebuild them to fit the shorter shafts - canley classics used to provide ready made ones, but they don't anymore.
The custom spring looks like it could be the most expensive option (around 300 to 400 to get it made up) but actually fitting it would be far easier than the other two options. So at the moment I am tempted to pay more money just to get an easier fix, but still haven't decided really.
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