Fulvia S1 subframe measurements

[bmarler]

it may not be possible to gain that much movement without cutting and re-welding the outriggers. you may also want to re-install the bolt-in crossmember at this time too. i would make some alignment bosses to locate the outrigger holes before doing any cutting. i think you're on a good path, it will be good when you're done to know the subframe is as it should be.

[piggdekk]

I managed to bend the outriggers back to the correct height, but that revealed some extra damage on the beams and another crack I did not notice before. I will need to cut and patch, but I feel like I'm on the right path. It's indeed a very time consuming job because one never knows when they have reached the correct position. To bend them back close to 82.5 (+/- 1mm) from 97mm I had to overbend neraly 3 cm. Once the subframe is on the jig with relatively light hand pressure it's easy to bend the outriggers by 1 cm. They are that flexible! Clearly the whole front end is designed to have plenty of flex.

[Huib]

Hi

I upgraded the forum to be able to install better spam defenses. There are quite a lot of spam messages. One of the things that will be installed is a country filter. Visitors from Western Europe, North and South America, Australia, New Zealand, Japan will see the forum. Others will see a white page. Let me know if anything unwanted shows up. Please store my email address before the page goes white.
I made some photo's which I will upload in one or more postings. I will see how it goes.

Playing a bit with it to get the feeling, is the best you can do. Brilliant. Once your jig is in order you will see it is probably easier than you thought.

The only parts that do not flex are the two alloy towers. Also the construction of the two towers with the three cross members is pretty solid. That is your “center of universe”. It is sacred. In a manner of speaking course. The car is put on top of the towers. The large subframe is to keep the thing up right.

What are the options? Here is one.

Put the car up side down. Mount the towers with their rubbers in their holes. Align the towers and cross check. Place the subframe on top and check that all the bolts fall freely into their holes. The bolts are the 8 pcs M10 bolt and the 4 pcs M12 bolt. And check all the off sets.
Then bolt the three cross members (1 at the top, 2 at the bottom) between the towers. Check all dimensions. Put the assembly on the car again which is still upside down. Check that again the bolts go in easily.

The support for the subframe at 80 mm'. It is rather strong and good for bending work at the out riggers.I do agree with bmarler that you should bolt in the rear cross member. There is play on the bolt holes. You have room to adjust that the two cooperate.

Hanging up side down is the bracket to hold the rear of the sub frame in place when cutting and welding has to be done. We can also slide on supports for the 2 mounting holes at the front and the two outriggers. The slide-on's are for measuring up side up or up side down. Others are for clamping either way.

[Huib]

Here a pic of the sub frame which is now being built up on the table.

Below some pictures of a sub frame of one of the cars we are now working on. The car is a 74 coupé from Napoli. It was in storage for most of the time. The sub frame is unmolested and no rust. We soda blasted it. The factory did put the black paint directly on the steel. We put an anti rust primer and on top nero semilucido. We developed that paint to match the shine of the black the factory used. Putting the extra layer of primer makes it necessary to re-torque all bolts after a few 100 km. We think it is worth the trouble as the protection is quite good for the climate here in the Netherlands..

[piggdekk]

Well done on the forum upgrades, I'm not an IT person, but I do know that it takes a lot of effort and time to implement any IT change (I've learned any IT development ends up costing twice and much and deliver half of what one expected). I much rather work with metal.

As for the subframe thanks a lot Huib, very useful. The body is currently at the body shop on a celette and I cannot put it upside down, but I can (and will) do all other checks. I'm very close to have it all at the correct dimensions +/- 1mm, hopefully today it'll be done. Then I have to patch the cracks on the left longitudinal beam, I'll put a picture later today, it does look nasty, I'm planning to weld the cracks, but then add also some gussetting on top on both beams to make it simmetric. Since this is mild steel I guess they are fatigue cracks, like the ones I found on the body mounts that are being replaced at the body shop.

Couple of question on your pictures:
- The spot welds on Your subframe look all new. Do You redo all of them prior to paint?
- I am torn on the subframe finish. I was inclined to use powder coating and not paint, but while one can easily match the semi gloss finish with powder coating I'm worried it may look too different compared to the original finish. Is this the reason why You have them sprayed rather than powder coated? Or are You concerned that heating the subframe in the oven might warp it?
thanks
luca

[Huib]

My pics show 2 different sub frames. On both the spot welds are original. I have never had problems with the spot welds on the sub frame. Replaced many outriggers though.

The black sub frame was powder coated 15 years ago. It pieces chipped off. It was warped and needed other corrections including welding. We took the powder coat off with the rotating steel brush and hand painted with a rather expensive paint.

I going away from the powder coat.

[piggdekk]

I'm very surprised that powder coating did not held, maybe there were some issues with the preparation, but I do agree that is a pain to get off if You need to.
Here are my spot welds and cracks, not a pretty view:

Racing is clearly very hard on the whole body. On the spot welds the 2 sheets were already separated but more like sliding on top of each others, not splitting. When I bent back the outrigger they opened up a bit. The cracks were already there.
I need to bend the upper (in the figure) sheet metal back to overlap the bottom one and weld it. Then take care of the 2 cracks. I will most likely make a hole at the end of the crack to stop it, weld it and then weld a gusset on top of the weld extending 3-4 cm both ways. I think it would make sense to add a simmetric gusset on the other beam too.
I'll keep You guys posted.
luca

[Huib]

Oops. Looks like someone butchered it. My nipotina who turned three a month ago would have done a better job but she has different plans.

I would consider getting another one. Sub frame that is.

[bmarler]

i don't use powder coat or any other fairly brittle coating (like por15) on chassis parts. as they flex, cracks occur and water migrates under the surface. this also happens with a rock chip. by the time you notice a problem the damage is worse than it appears as the moisture has penetrated a considerable distance. i use a paint called zero rust as it has a proper amount of sheen for chassis parts and is easily repairable should you get a chip or other defect. other people i know use a paint called rustoleum. this would be a similar chemistry to zero rust. if you want it a bit harder on the surface, you can add acrylic enamel hardener to the rustoleum and it will toughen the finish. be aware that adding hardener will also increase the gloss. i use the zero rust paint directly on bare metal. if a texture is desired, i use a spray on urethane coating like upol raptor before painting. these products are easily available in my area, but maybe not for you. but i'm sure there are comparable product where you are.

[piggdekk]

Huib,
I had the feeling the subframe had been fixed before. There is a fair amount of weld spatter where the outrigger joins the longitudinal beam, but I can't really tell. The crack by the outrigger seems to be coming from there.
The other crack (the longer one) is right at the limit of the last spot weld that failed. My theory is that load on the outrigger twisted the beam, and bent inward the sheet metal up to the point where the spot welds gave up. This outrigger was 15mm lower than where it should have been!
I have been looking for another subframe, but I cannot find any good one in Spain, and I would need to have it shipped form Italy. The ones I found all look pretty nasty and they will need some degree of repair anyway. If I could find a good one I would go for it!
Thanks for the hint on powder coating. I've always assumed that it was quite flexible since it's used also on springs, but looks like I was wrong.
luca