Which Brake Flare Type?

[ede smith]

2001 Buick Cenrtury

Wanting to buy a brake flaring tool to replace my lines but I am getting conflicting information. A prior post here says it's a DIN bubble flare (Same as ISO bubble flare), but I've also read it is an inverted or double flare. Which one is it?

 

[ede smith]

Well ask AI and you will get 3 different answers, It went back and forth from double flare to DIN bubble flare and even using different AI chat bots. It also said there was a chance that they use both. I am leaning towards that they are all DIN bubble flares which are oddly utilized on European vehicles.

Now to figure out a decent flaring tool, then decide on pre-bent lines or getting a roll of Ni Copp tubing.

Some folks use the first step of a double flare bender in lieu of a special DIN bubble flare bender which I'm not sure is correct as they sell special ISO/DIN bubble flare tools. Can anyone confirm?

 

[ulycyc]

GM uses double flare brake lines especially on older models like yours. Bubble flare may be on GM cars made overseas. Making double flares will be hard to make without splitting if you buy cheap rolls of brake line. I would spend the extra money and buy ready made custom fit lines from Inline tube or SS brake. Both are around $200 for a complete set

 

[ede smith]

It's amazing how many different answers I have been getting and would have expected double flares to be the most obvious.

I think to avoid the confusion I will probably get pre-bent lines.

Here is the last answer I got:

Confirmed: 2001 Buick Century Uses ISO (Bubble) Flares​

1. Buick Forums Expert
   A trusted user shared from direct experience:
   
   

   “They are ‘Bubble’ or ‘ISO’ flares, not a double flare… Despite what the internet tells you, you need a bubble flare tool.” Buick Forums

2. Buick Reatta (Similar GM Models)
   A detailed discussion—though about another model—makes the distinction clear:
   
   

   “My Reatta… uses a flare called an ISO flare. … Do not let the counter People tell You that all that is, is a double flare. It is not and They can NOT be interchanged.” AACA Forums

3. Reddit Confirmation
   In a conversation about GM brake line standards:
   
   

   “Older brake lines require a double flare… But newer GMs (mid‑90s and up) use a bubble flare which is a different flaring tool.”

 

[ulycyc]

"AI" is as good finding the correct parts as finding a replacement wife. Yes buy the pre-bent lines