how its made - the conrod

[therealnovaboy]

when doing my engine rebuild on a x16xe i noticed that the big end bearing cap on the conrod was not machined. it looks like when it was made in the factory the conrod is cast with the rod and bearing cap as one piece then the bearing cap is then snapped off. the bearing cap is not machined flat and neither is the conrod so when it is bolted together the two ruff faces mate together perfectly.

to my understanding a conrod is usualy cast with no big end hole then the bit that becomes the bearing cap is cut off. these are then machined flat to get a good fit hen the big end bearing hole is drilled.

what i am wondering is how they make the x16xe conrod. do they drill the big end then snap off the bearing cap. or snap it off before they make the hole. how do they mass produce this and snap off the bearing caps without having loads of conrods that dont meat the spec where they have not snapped in the right place or snapped into more than one piece.

anyone any idea?

[Mike]

Both the rod and end cap are injection moulded or cast steel parts made in 2 seperate moulds.

Once cured and released from aforemention mould/cast both peices would then machined down (CNC machined, minimal room for error).

[therealnovaboy]

Both the rod and end cap are injection moulded parts made in 2 seperate moulds.
(CNC machined, minimal room for error).

how can they be in two seperate moulds. the only face that is machined is the bearing seat. the faces that touch together on the rod and bearing cap are not machined, they are not even flat and none of them are the same. if you got two different rods and swaped the bearing caps they would not fit. this is why i think the bearing cap has been snapped from the rod in the factoy.

[Dar]

The big end of the rod is fabricated as a unit and cut or cracked in two to establish precision fit around the big end bearing shell. Therefore, the big end "caps" are not interchangeable between con rods, and when rebuilding an engine, care must be taken to ensure that the caps of the different con rods are not mixed up. Both the con rod and its bearing cap are usually embossed with the corresponding position number in the engine block.

Recent engines such as the Ford 4.6 liter engine and the Chrysler 2.0 liter engine, have connecting rods made using powder metallurgy, which allows more precise control of size and weight with less machining and less excess mass to be machined off for balancing. The cap is then separated from the rod by a fracturing process, which results in an uneven mating surface due to the grain of the powdered metal. This ensures that upon reassembly, the cap will be perfectly positioned with respect to the rod, compared to the minor misalignments which can occur if the mating surfaces are both flat

[Mike]

The big end of the rod is fabricated as a unit and cut or cracked in two to establish precision fit around the big end bearing shell. Therefore, the big end "caps" are not interchangeable between con rods, and when rebuilding an engine, care must be taken to ensure that the caps of the different con rods are not mixed up. Both the con rod and its bearing cap are usually embossed with the corresponding position number in the engine block.

Recent engines such as the Ford 4.6 liter engine and the Chrysler 2.0 liter engine, have connecting rods made using powder metallurgy, which allows more precise control of size and weight with less machining and less excess mass to be machined off for balancing. The cap is then separated from the rod by a fracturing process, which results in an uneven mating surface due to the grain of the powdered metal. This ensures that upon reassembly, the cap will be perfectly positioned with respect to the rod, compared to the minor misalignments which can occur if the mating surfaces are both flat

Well, there you go then lol i talk sh1t and Dar is correct lol

On another note, you live & learn as i never knew the aforementioned (not that ive ever had to know it TBH).

[therealnovaboy]

so how do hey fractue it and insure that it doesnt break into more than 2 bits and is the big end hole machied then fractured or fractured then machined.

[Stuart]

so how do hey fractue it and insure that it doesnt break into more than 2 bits and is the big end hole machied then fractured or fractured then machined.


they have nicks in the point at which the break is desired/calculated to happen at.

Rod designers arent ****wits lol

[MK999]

small indent around the conrod is enough to make sure it snaps clean surprisingly. Machined then fractured.

Another method used is to have a zigzag pattern cut between the cap and rod, in an unsymmetrical pattern so the cap only fits right one way round. that was on a volvo engine I believe. It's just another way to make sure the hole for the crankshaft is perfectly centred and fits nicely inside the big end bearing shells.

[MK999]

Rod designers arent ****wits lol

Not even the cadbury scooby ones?! lol

[Stuart]

Not even the cadbury scooby ones?! lol


thought the pistons were choccy ;)

[Dar]

so how do hey fractue it and insure that it doesnt break into more than 2 bits and is the big end hole machied then fractured or fractured then machined.
http://i21.photobucket.com/albums/b254/The-619/TripleHWithSledgeHammer.jpg

[MK999]

thought the pistons were choccy ;)

Fail, thought they liked throwing rods through blocks :(

[Stuart]

Fail, thought they liked throwing rods through blocks :(


Thats just Lee