Welding Tips and Tricks

hi guys, i have a question?,can i weld different types of materials coz my boss wants me to welding the connecting rod for the aluminum crankcased for his design,its kinda weird but i really need youre good opinions. thanks

Connecting rods are typically steel. Welding the caps to the rod is a terrible idea because the rods should have a bearing internal to them as the rotate around the crank. Welding them will prevent proper clearance of the bearing, and likely disrupt oil flow to the bearing.

I’m confused about your comment of the aluminum crank case, because the rods have no interaction directly with the cases. The crank rotates within the case (in journal bearings) and the cases simply house the crank assembly. You can not weld steel to aluminum.

Your boss is either a genius or an idiot... I’ll wager on the latter.

I believe we need more info. It’s not uncommon to have aluminum connecting rods in refrigeration compressors. Some of them see much higher stress and compression than what you would see in automotive applications. But generally they see lower temperatures than a gas engine. I’m not sure about large gas engines but it wouldn’t surprise me if some models use aluminum connecting rods because some small engines definitely do.

When you say welding different metals we need to know exactly what the two metals are. Even if there weldable it may become an issue of not being able to get enough surface to weld togeather to get the strength or stress resistance you need. That almost becomes an issue of its own because now your talking about geometric design and layout for the given application.

yeah i know my quetions sounds crazy mate,coz my boss want me to design same same like this tables.thats why kinda ask some crazy question here,got so much tension of project.

heres the engine guys he wants me to be weld,in his engine table.,sorry dragging this kinda problem in this forum, i know for my self that this would not work,but i dont have a choice,my boss doesnt know anyting about tig welding.

Actually it’s a perfect question. From the looks of the pic it’s a cast aluminum block. So as long as the rods are some kind of aluminum then it’s definitely possible. Since it’s more of a decorative purpose strength my be less of a concern.

I seriously doubt the rods will be aluminum, as very few motorsports applications ever used ally rods.

A better approach for attaching the rods might be to weld some brackets on the bottom of the case that the piston wrist pin would pass thru (essentially mimicking the piston connection) and the rod big end (where cap would be) becomes the foot.

Or, use the piston which is very likely ally, to weld it to the case, then use the wrist pin to connect the rod, big end to the floor. Only downside here is the wrist pin will rotate some to allow the rod to move the diameter of the piston skirt.you could of course invert the piston and put a small TIG on the pin as it passes the small end of the piston.

Any of that make sense?

cj737 wrote:I seriously doubt the rods will be aluminum, as very few motorsports applications ever used ally rods.

A better approach for attaching the rods might be to weld some brackets on the bottom of the case that the piston wrist pin would pass thru (essentially mimicking the piston connection) and the rod big end (where cap would be) becomes the foot.

Or, use the piston which is very likely ally, to weld it to the case, then use the wrist pin to connect the rod, big end to the floor. Only downside here is the wrist pin will rotate some to allow the rod to move the diameter of the piston skirt.you could of course invert the piston and put a small TIG on the pin as it passes the small end of the piston.

Any of that make sense?

Respectfully a quick google search will show you that aluminum rods are not uncommon in motor sports.

The last street car I had had Aluminum rods in it, 522 cu in Super Cobra Jet.

pgk wrote:The last street car I had had Aluminum rods in it, 522 cu in Super Cobra Jet.

Aftermarket and higher performance applications often use ally rods, but they are very uncommon for stock street motors. Let’s see what the OP comes back with in the actual material his are made from.

Agreed. that motor was anything but stock lol..