Sprint 6C build up

Ive lowered my 33 a while back. Got the springs from justsuds. The springs are quite a bit shorter but it didn't have the impact i was hoping for when i dropped it back onto its wheels. Guess my original springs were completely shot but the reduced length may be enough in this situation.

Originally Posted by kevjtd

what about lowering springs for a 33? they must be available somewhere? think you may get dificulties getting it low enough without the weight of the engine to compress the springs?
sure someone will come up with a solution

Make the front into a boot and stick a few bags of sand in there

Originally Posted by Pud237

Make the front into a boot and stick a few bags of sand in there

what about springs from something like a fiat x1/9? something designed with a rear engine?
wouldn't ordinary sud/sprint/33 springs be too stiff without much weight on them?

Demon Tweeks do a range of generic springs, if you have an ideae of length and stiffness then they may have some off the shelf.

I have some Sud springs that came off a racer, lowered and about 175lb, so while not stiff enough for racing, maybe too stiff for the road?

In fact, I have some lowered 33 front springs, post the lenght and coil thickness of your standard springs and I'll compare to the 33 set and see of they might help you.

Originally Posted by Alfasixnut

....... Has anybody else done a similar job?

these guys have.. Giocattolo. I'm sure a search around the web on this car will reveal how they sorted the front end.

Originally Posted by veesix75

In fact, I have some lowered 33 front springs, post the lenght and coil thickness of your standard springs and I'll compare to the 33 set and see of they might help you.

Hi Tim
The Springs are still on the struts so I cannot say what the free length is, (At least 8.5") - (The Haynes manual says the free length is 11.5") but there are 4 coils and the wire dia is 0.55" - According to the Alfa BB thread the rate of the Sprint front spring was 130lb/in so the shorter stiffer 33 springs may be suitable...

Hi Sixnut - if you are keeping the front struts, cutting coils off the spring to lower the stance will increase the spring stiffness, so the front will be lower, but you'll be skipping all over the place. You definately need softer springs, which should compress more and lower the stance that way.

Is there enough room under the bonnet to raise the strut top mounts? That would lower the ride height without changing the spring rate. You'd still need softer springs though, you've taken out an engine and transmission + driveshafts and you are putting only a fuel tank in their place. What would that equate to? A 300 lb reduction? Split between the two front wheels 150 lb per wheel, same as the spring rate, so at least 1" higher at the front.

To do the job properly you need to know the corner weights, and measure the unsprung weight of the strut/wheel combination, set a target suspension natural frequency (cruiser/sporty/full race/GFX) and work out the resulting spring rate. As the natural frequency at the front needs to be lower than the rear to stop front/rear pitching effects, for your mid engined machine the front spring rates will need to be quite a lot softer than the rears (which are 164 struts, what is the spring rate?). You won't find any Alfa springs at rates of around 100-120 lb/in (which I think you would need), I would check out manufacturers who can wind a custom spring, or as Kev suggests, maybe the front struts from an X1-9 would do the job (they'll be shorter too!).

Conversely, now that most of the cars weight is on the back wheels, you might find that the 164 springs are too soft. There again, the Sprint shell is probably lighter than the 164 bodywork, but my point is you will need some fine tuning or the car will be a nightmare to drive (and I've got three complete sets of redundant springs in the garage to prove it!)

Green Machine has a custom fabricated alloy fuel tank. Its TIG welded and had a number of pinhole leaks which had to be painstakingly rectified (not by me, my welding is of the "pidgeon poo" variety ) with the tank removed from the car and drained out. Fuel tanks can be fabricated out of steel as well, which might be easier to do.

With plenty of space under the bonnet, I would go for a proprietary racing tank, one of those alloy ones or if you are feeling flush, an ATL fuel cell.

Still making excellent progress. Nice beading on your engine bulkhead by the way

Lauren

why not get a 2 1/4" universal coil over kit, it will save a lot of messing around and give you the benefit of playing with lengths and rates, as long as your struts have inserts its just a case of cutting of the top lip and spring seat..heres an old pic of my strut.

Well LOTS of food for thought with very useful information from Kev, Lauren and Alfa 302.
Trying to pull lots of it together, the standard springs seem to have a low spring rate - 115lb/in (?) but are compressed or preloaded in the suspension strut by about 3" so with the weight of the engine etc the spring only compresses an extra inch or so to give the normal ride height.
So if I do remove a coil the preload will be less, the Spring rate about 160Lb/In and the ride height lower. But the front may well skip about. The rear is also effectively stiffer and the springs have less weight on them as the Sprint shell is much lighter - but the other factor is that the engine is in fact more Mid mounted -- I think it will have to be tried then Ill find the corner weights etc and retune the suspension in the light of experience - Also I have little money for nice "exotica"

Try this site Professional Motorsport Parts, Spares & Rally Equipment from Rally Design they have roller bearing top mounts 2 for £119 and a universal conversion kit 2 for £63 add a pr of springs for about £30 and your done, or try surfing the net for a better deal. With what you have done already it would be an easy conversion and no guessing work involved. Heating and cutting springs is not something I would do as you may find one spring is harder than the other...what ever you decide to do, best of luck

I'll definately second that!

The universal strut option looks like a good bet, but the range of spring rates/lengths needs to be sufficient to cover Sixnut's extreme case of an Alfa Sprint with no engine or transmission (not a common request I suspect ).

I tend to agree with your appraisal Sixnut - get the thing on the road and see how it feels, then change spring rates as required. With a bit of luck you'll find the rear is fine (doesn't wallow, but at the same time isn't dancing all over the road) and all you need to do is adjust the front spring rate/length.

Unfortunately Green Machine started off with 250 lb springs all round, which made it too soft at the back and too hard at the front. Plus the ride height was too low because they were all too short. Next iteration (again pure guesswork) put longer 300 lb springs all round. Even worse.

When I finally got the corner weights measured, I found that my suspension natural freuqencies were at F1 levels at the front (OK, maybe F3000, but still waaaaay too high), while the back was OK, but perhaps on the softer side of "sporting".

So I had to do a third iteration based on a more scientific analysis of the suspension, but you should be able to do the same job in two bites, and hopefully you will only have to spend money once!

By the way, my spring rates are higher than the strut rates because I am using wishbones all round and the spring/damper units are (a) inclined relative to the vertical and (b) not acting directly on the wheel axis so there is a force multiplication factor involved. However, I recently analysed a colleagues Nova (kit like mine, only with the original VW running gear) and his direct acting coil-over replacements for the Beetle front beam came out at 110 lb/in per wheel. No water radiator up front in this case, but dual batteries and a heavy fibreglass layup makes me suspect that your front spring rates aren't going to be much higher than 120 lb/in...

Its going to be a riot when its done

Lauren

had a look for springs on the above site, they have 100 lb rate at 8" for 14.90, so guessing(which i do not like doing) if they compress 1-2 inchs they could be the right height just need to check the rate..the front kit is £42 not £63 as i said before that was for the rear kit so even better value..any chance of it being ready for march/april 09?

Lauren - your technical analysis and appreciation of the problem is spot-on! There are so many variables that a trial and error approach will have to be adopted.
My bulkhead bending was complicated by the fluting on the bonnet and reinforcing struts behind - but it will look better soon.
This also means that Alfa 302's query about "finish" date could be about right, in as much as it could be up and running, with all systems in place by Easter next year - but still needing cosmetic bodywork tidying up - which will take ages!! (And thanks for the "Rally Design" link, there are all sorts of useful bits - once I get some money!!)
However I will have to swap Sprints soon, to assemble, and sell off the 1.5 Sprint.
I am, at present, investigating the GTV (1977) fuel tank as a possible solution to that problem ....

Further progress as I now have a GTV fuel tank to try - and it seems to fill the engine bay very nicely. ....so here are three more pics showing the 164 radiator in place with the fuel tank just positioned roughly behind. Obviously there are mounting brackets and lots of pipes to get made and connected.