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Ref: my twin-turbo Maserati-Dino project - I have a welding question...

I've been busy since my last post, with part of my mission being to work out how to deal with the four corners of the car. The stock Dino wishbones, wheel hubs, brakes and wheels have got to go as quadrupling the power to weight ratio is clearly going to require substantially improved components.

The Maserati M156 brakes are enormous - almost certainly over the top, but I'm not going to complain about that. So they're going on.

Although the Maserati wheels are far too heavy, they are of suitable sizes. Since they can be changed later on when I'll know more about the required offsets, etc. they'll do for now.

The Maserati wishbones can't be used for a number of reasons, the three main ones being 1) that the front upper part of the upright/wheel carrier would actually go through the bodywork as its so tall, 2) there's no chassis in the required place on a Dino to attach the upper arms, and 3) the arms are so long the geometry would be plain wrong.

This dilemma led me on a long research journey, going through the set-ups on hundreds of different potential donor cars, but none were exactly as I wanted. The best solution appeared to be to fabricate my own wishbones using some uprights/wheel carriers off something else. I did consider making my own uprights until I discovered the cost of the required slabs of ally. In the end, the nearest ones I could find were those off a Maserati 3200/4200, so I bought four (3200 ones for the fronts, 4200 one for the rears, simply because that's all I could find).

Although the positions of the wishbone attachments on these are fine, the wheel bearing hubs off the M156 don't fit the 3200/4200 uprights, and the 3200/4200 bearing hubs don't fit my wheels. Also, I have bearing hubs for the M156, but none for the 3200/4200.

So - I now have a new problem. While I can bore out the 3200/4200 uprights by 20 thou or so to take the M156 bearing hubs, the bolts that hold them on are in different places. The new bolt holes more or less miss the originals (as per the photo), but there isn't enough metal to do this without adding some additional support. I can make up a plate to do this, but ideally I feel it should be welded in place. My question therefore, is not whether it can be welded in place (it clearly can), but whether anyone has any experience with what this would do to the heat treat condition of the upright?

First up...when did the build plan get twin turbos? Do the words scope creep mean anything to you?

2nd, my god you like making work for yourself! A couple thoughts, the front suspension really doesn't care how much hp you add to the rear, the loads there don't change with anything but weight and tire changes. You mentioned brakes, I promise the old brakes would lock up the tires so the new big brakes aren't adding any new loads, they are letting you maintain the load for a longer time. In the back it comes down to how much grip you have more than how much hp you have. My car spins the rear tires in 1st through 3rd gears so the tires are kind of like a fuse. I read that OEM stuff it designed for somewhere is the 3-9g range, big modern slicks will get you about 1.5g for braking or accel (if you have the power) so that is not going to brake the suspension...axles maybe but not the suspension.

Modern carriers will let you make everything a bit more rigid. They are designed to fit in larger wheels so they are taller and that spreads out the loads at the carrier but more importantly at the chassis and that means the chassis can be lighter for the same flex. You can probably also do a bit better on geometry....this is the one I'm going round and round with trying to decide how how I care. Better geometry can give near optimal tire contact over a wider range of conditions but I've watched gokarts with no suspension at all set time of the day at the last few autocrosses I've been at which as convinced me not to go crazy upgrading stuff as I can certainly dial in what I have to work where I plan to use it. Anything that is done and working is WAAAAAY better than a perfect design that isn't done...ask me how I know

3rd is your question which you already know the answer to....if you weld the carriers they will no longer be heat treated anywhere near where you welded. I welded on my carriers and they have been fine but I guess the actual right way to do it is use a heat treatable rod

https://esab.com/us/nam_en/esab-university/blogs/heat-treatable-vs-non-heat-treatable-aluminum-alloys/

The common filler is 4043, welds really nice but not heat treatable. You can still have the part re heat treated but the weld will stay soft and that could be fine provided the weld area is about double the base metal. Or you could use something like 4643 which will harden...I've never tried it to comment on how it weld buit it will let you get the part back to full strength.

There's no mission-creep - while I was originally going to use a non-turbo 458 engine, when I found out that someone is already doing that I had to step it all up a notch. That's why I bought two crashed Quattroporte VI GTS donor vehicles - which have twin-turbo engines out of the same family as the Ferrari 488.

As for the geometry - my plan is to build the car with as close to stock settings as possible, but to have the key things adjustable. To that end, I intend to use rose/Heim joints at both ends of the wishbones. The camber - which is determined by the mounting points on the uprights will not be independently variable, but the KPI will be. There will be a small amount of castor adjustment too.

Regarding the welding - I'm not really concerned about the heat treat condition of the weld itself, more what the heat involved will do to the rest of the uprights!

I didn't realize the mazer was TT, should have googles and wait, someone else is building a 458 powered 246? what?!?!?

What i was on about with the suspension is that you can get almost anything to work well, but the weirder it is the more limited the conditions it works well within....the gokarts I mentioned bounce so they were taking odd line looking for smooth pavement to maintain grip. Super sticky tires want to be at around 3deg camber in the corners so look odd and wear more going straight. Just stuff like that where geometry more suited to the specific application can mean less comprises in performance but more compromises trying to build it.

A design mistake I've made in the past is focusing on weight over adjustability. On the formula car I designed rod ends threaded into the A-arm tubes. very strong and light but we had to unbolt the aarm to make camber adjustment which made doing alignments a very slow process. Today I would make sure I can just turn a nut to make the change. Little stuff like that just makes life so much easier.

When you weld the upright the base metal anywhere near the weld will be annealed. As you move further away to will change from annealed to over aged (soft and brittle) which is why welded alum often cracks rear the weld not at the weld. The parts you have are new (pretty high safety factor baked into the design)and designed for a much heavier car.....I wouldn't worry about welding them but the absolute best wat to do the job is use 4643 rod and and send them for heat treat after welding.

Many thanks for the benefit of your experience - I don't know 4643 rods - I'll check them out!

The chap who is building the 458-powered Dino is the same person who built the 328 and Mondial/F40 (depending on whose PR you believe) engined-Dinos.

Edited to add: It seems that 4643 (aka AMS4189) rods are not commonly available in the UK. I'll have to see if there's anything else equivalent.

Having gone down this road as far as I have, I've realised that I'm simply not 100% satisfied with the idea, so I've gone back to my original solution - namely, to make an adaptor plate. To this end, last night I ordered up an offcut of six-inch titanium bar, from which I shall machine the relevant components. One side will bolt to the hubs - as per the M156 Maserati, and the other side will bolt to the uprights - again, as per the factory design. The centres will be located using the same raised step method as the originals.

This will, of course, mean that both the discs and wheels will be shifted outwards. As I will be having new wheels made later on in the process, that side of things isn't an issue, and since I have to make new caliper mountings anyway (as the holes are in the wrong places), I can deal with that too. Onwards and upwards!

I can now state with 100% accuracy that I'm utterly sick of machining titanium... Still - my new adapter plates are almost done - just got to stick the holes in and the wheels should bolt up.

I wondered when you said titanium if you knew what you were getting into

Oh yes, I've had a lot of experience with machining titanium over the years - I've just never had to turn a 6 kg (13.2 lbs) round billet into four separate pieces that together weigh about 500 g (1.1 lbs) before, where literally every possible millimetre had to be used; I'd have killed for another half inch! There wasn't even enough material to do a parting-off operation for the last two components - I had to run the lathe at 50 rpm and use a hacksaw*. What didn't help was that I ran out of coolant halfway through it all and was reduced to using a syringe to suck up the last residues.

I still haven't finished as I had to suspend the last stage (putting the last four holes in each adapter) as I needed to mount the uprights in the mill and bore out the hub bearing bores so that the new plates could be offered up in order to get the hole alignments right. That, of course, meant machining up the relevant parts so that I could hold the parts steady while they were being milled. I got two done today, and hope to finish the other two tomorrow.

* Please don't try this at home...