On many pre-1988 E30s, the lines that originate from and lead to the reservoir (low pressure) terminate in banjo connections that consist of a hose and a band clamp.

The two lines are:

16X22MM 32411131545
12X18MM 32411131524

The hoses adhere to a DIN standard that is NBR/CR: NBR inner, single textile reinforcement, CR outer (abrasion-resistant outer rubber layer) DIN 73379.

In North America, it’s much more common to find SAE-rated hoses, and the ones used for hydraulic lines (like those for power steering) are in the SAE 100R series.

The OEM DIN hoses adhere most closely to the SAE 100R6 standard. The 16x22MM hose is the same size as a 5/8″ ID hose, and the 12x18mm hose is most similar to a 1/2″ ID hose.

The added benefit of SAE hoses is that they are normally wrapped over the outer rubber layer, which provides an additional layer of protection between your band clamp and the hose.

But let’s say you want to improve even further on OEM, because let’s face it, OEM is ‘good enough’ but doesn’t strive to be the best possible available, because in the real world, cost mattered when the car was built.

You can choose to upgrade to either an SAE 100R3 or SAE 100R4 hose. The primary difference from SAE 100R6 is that there is an additional layer of textile reinforcement in the 100R3 specification, and a steel spiral in the 100R4 specification. The steel spiral provides significant resistance to collapse due to bending and vacuum.

The challenge is that SAE 100R4 is available as a single or double textile reinforcement, so it’s best to source out a double textile reinforced option.

The second challenge is that SAE 100R4 can’t be sourced smaller than 5/8″ ID, and therefore you can only use it to replace 32411131545. To replace 32411131524, you have to use SAE 100R3 instead, as it goes down to 1/2″ ID.

In reality, there is virtually no bending or vacuum occurring on the 32411131545 line, so you can use SAE 100R3 or 100R4 interchangeably, but this may be something to consider if you’re swapping an engine.

SAE 100R3 is always double textile reinforced; ensure that you select an option that includes the outer rubber wrapped for the aforementioned additional layer of protection.

This entry was posted on January 9, 2024 at 1:31 am and is filed under Interesting Stuff. You can follow any responses to this entry through the RSS 2.0 feed.