Fulvia S1 subframe measurements

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Huib
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Re: Fulvia S1 subframe measurements

Post by Huib »

@lancia7550
Very good procedure if you are doing a limited number such as restoring one for your self. Each year we have quite a few of "sub frame cases". That includes collision damage.

@Luca. If you say the RH rear mount is low, then perhaps you say the 1C point is high when the RH outrigger is bolted to the car. That would mean the caster angle on the right is too small. Well, it usually is. I wonder what side usually has the lower caster angle in the UK or NZ.

I drive very slow but still hit every curb and pothole along the road. My colleague Wainer from Torino who started his career with the Giaveno race team as well as with Lancia over 35 years ago, drives twice as fast and is very good in avoiding obstacles. He is also extremely accurate when putting a car together.

I uploaded some pictures with dimensions and tools.
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Forum spit1.jpg
Forum AST0890I.jpg
Forum AST0847I_0202.jpg
Huib

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Huib
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Re: Fulvia S1 subframe measurements

Post by Huib »

And.

If the 1C point on the right is high and the caster low, then most likely the RH top mounting hole for the alloy tower is no longer true.

And

Didn't you say the subframe has an 818.330 number? I doubt that is a Zagato subframe.
Huib

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piggdekk
Posts: 28
Joined: 19 Sep 2020, 12:07

Re: Fulvia S1 subframe measurements

Post by piggdekk »

Hi Hiub,
thank You so much for sharing so much infomration.
Yes, the subframe is not the original one. Since this car has been racing for about 30 years that should not come as a big surprise. According to the manual they should all measure the same though,

The body work has measured the body and it turned out to be on spec at least on the horizontal plane. This is a very good body shop specialized in vintage and race cars, no reason to doubt their measurements. My only concern is that they mostly work on Porsche, so may not have direct experience with Fulvia's. They do the body, I'm taking care of restoring everything else.
I do have some concerns on the height of the top mounting holes of the alloy towers. Most of the spot welds in that area were broken and the body has a lot of flex with some fatigue cracks. This is why I'm so interested in getting the subframe 100% right. There will be reinforcement there, but needs to be welded on a straight body!

I just ordered the beams to built the jig today, so later I'll have a solid tool to take accurate measurements and straigthen the subframe. Unfortunately I don't understand what you mean with "point 1C". To which drawing are You referring to?
Another question: when I posted the DT with body measurements You mentioned that the line named "HO" is not the position of the fron subframe mounts. Do You know what HO is referring to?
many thanks
luca
Huib
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Re: Fulvia S1 subframe measurements

Post by Huib »

You are right. The subframes have the same sizes. It is just that the deformation of subframe will not match deformation of body.

I just asked Wainer. The H.0 line means Altezza 0, height 0.
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piggdekk
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Re: Fulvia S1 subframe measurements

Post by piggdekk »

Hi Huib,
when I've taken the car apart it already had this subframe, and the previous owner did not change it, It has been in there at least since the late 80's.It has to match the body.
Please, thanks Wainer for the hint. Given that H0 is the actual "0 level", what does 95.5 mm represents? I can only relate it to the difference between H0 and the front body mount, but I believe You mentioned that is not.
thanks
luca
piggdekk
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Re: Fulvia S1 subframe measurements

Post by piggdekk »

I made a small table and I think the offset make sense now and match the SAT and Your correction. I know this is very pedantic, but as they say "measure twice cut once"

Front Mid Rear
H0 da SAT 95.5 416.5 64
Silent Block tra subframe to chassis 21 29 39
Alloy tower 360
Suframe contact point 74.5 27.5 25
Offset 0 47 2.5
piggdekk
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Re: Fulvia S1 subframe measurements

Post by piggdekk »

Hello,
so the jig is nearly ready. I fixed the 2 longitudinal beams at +80, and when I measured the front offset it turned out to be very close to 47 mm. What a relief. It would have been hard to move it. It definitely paid off to have a very solid reference. The 2 beams were also twisted and not parallel, but I got them parallel torquing the screws on the jig. Next step is getting the outriggers to behave, they are so much off... The height compared with the longitudinal beams should be 80+2.5, but they are at 93 and 95mm. I hope I don't need to pull the acetilene.
I'm quite surprised that the outriggers aren't wleded on the top and bottom junctions, but only on the vertical ones, that does not help to keep them straigth and definitely adds flexibility. Flexibility is good until elasticity applies!
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piggdekk
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Re: Fulvia S1 subframe measurements

Post by piggdekk »

ok, so the jig is nearly completed. Am I correct assuming the height I've indicated in the picture is the -20.5 mm offset? I need to add a support there otherwise it will twist the longitudinal beams instead of the outriggers.
and by the way the subframe is so easy to bend! I was surprised to see how little effort it takes to lower the ourtiggers more than 10mm. My hope is that I can bend them back in spec using bolts and nuts.
dima telaio.jpg
bmarler
Posts: 81
Joined: 22 Dec 2008, 17:33

Re: Fulvia S1 subframe measurements

Post by bmarler »

i've been watching your progress on this project. one of the things to remember about metal is that it has a memory. if it's been moved from it's original position it will want to go back there again. but it usually takes a little overbending to get there as it will spring back after bending. when i make a fixture for indexing assemblies like this i will weld the fixture, brace it, and add the pickup points that are needed to ensure the alignment is correct. the idea being that the finished part will sit on the fixture in perfect alignment with no clamps or bolts required. certainly during the process of bending or pushing the metal back into position some amount of clamping or levering is required but in the end there must be no stresses on the part as it sits on the fixture.
it's perfectly ok to use heat to help you attain your goal too. heating the part will relieve some of the stress and help the part relax into it's position. not sure how huib feels about the outrigger mountings but i think i would weld them all the way around to add a little strength.
piggdekk
Posts: 28
Joined: 19 Sep 2020, 12:07

Re: Fulvia S1 subframe measurements

Post by piggdekk »

Hi Bmarler,
the goal is indeed to overbend it a bit to make sure it will eventually rest in the correct position with no effort.
The 2 longitudinal beams were far from parallel and I had to overbent them a lot before I could get them parallel again. Now they sit parallel even if they are not clamped. I'm planning to to the same with the outriggers, but I need to make sure that it bends in the right spot. I believe I need to add a vertical support where the outriggers is welded to the main beams to make sure it bends back to the correct position but it does not twist the logintudinal beams.
So far when I bent them down to 82.5 they just sprung back to 95mm also after heat was applied.
luca
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