Sunday, May 1, 2011

Isetta- Brake Lines

The sliding window Isetta 300 export version's brake lines consist of three hard lines and three flexible lines. When installing new hard brake lines, having a pair of brake line pliers will help facilitate nice smooth bends without crimping or pinching them. I picked a pair up from Harbor Freight for $14.00. Compared to other pliers I've seen at Harbor Freight, these are OK quality. I suspect they're coming out of the same factory as the ones Eastwood or other suppliers are selling for twice the price.

The Isettas hard lines are 4.7mm (3/16") diameter lines with what's referred to as a "bubble flare" The thread of the coupler nut is M10 x 1.0. This is a fairly standard size flare and thread for most European cars. The lengths of the three lines are:
Left Front - 24.75" (629mm)
Right Front - 40" (1016mm)
Rear - 44.5" (1130mm)

Isetta brake lines in the correct lengths are readily available from Isetta parts suppliers, however if you have access to a flaring tool, you can purchase steel brake lines from your local auto parts supplier and save a considerable amount of money. Virtually every auto parts store in the US sells hard lines manufactured by Poly Armour. You will want the PAE series (Poly Armour European). You can purchase the 40" line the correct length, however for the Isettas 24.75" and 44.5" line you will need to purchase lines that are longer and cut and flare them to the correct length. The parts numbers of the three lines I purchased are PAE-330, PAE-340, and PAE-351. The cost for all three brake lines was about $20.00.

Because I'm restoring two Isettas, It was less expensive for me to buy a tube flare kit and brake lines from my local parts store than it would be to buy two sets of brake lines from any of the Isetta parts suppliers. When I was researching tube flare kits, I noticed a lot of complaints about cheaper sets. The most common complaint about cheaper sets was that no matter how tight the brake line was clamped, it would slip in the clamping device which results in an incomplete flare. I ended up buying a bubble flare kit by KD Tools which gets very good revues. That being said, you do have to be sure you have the tube clamped VERY tight. I had bought an extra brake line to experiment with bends and test the flare kit. My first couple of test flares did slip because I wasn't getting the clamp tight enough. Once I realized how tight the brake line needs to be clamped, the KD Tools flare kit did a great job.

A couple of pictures of the old brake lines.

The old steel brake lines removed from the chassis. This is what the factory bends look like with the exception of........

When I was removing the body from the chassis, I could not separate the connection between the front flexible brake lines and the hard lines. I finally gave up and just cut the lines for the sake of getting the body removed.

A few picture of the new brake lines installed.

The Isettas three flexible brake lines are all 15.25" (387mm) in length. One end is male, the other end is female. The threads are M10 x 1.0. The outside diameter of the female end needs to be 14mm to work with the brake line brackets on the Isetta. One feature I like of the European Isettas with the horizontal front shocks is that the front brake line brackets are attached to the frame as opposed to on the body as they are on the export version. The advantage of that is you can completely install the entire brake line system with the body off. With my export versions, I'll have to wait until I have the body back on to install the two front brake lines.

Rear flexible brake line installed.


  1. can you tell me please do the rear brake springs go on inside of brake shoe hub or out side or is there one in side and one on out side of shoes.Thanks
    Like your site.

  2. Maybe this photo will help?

  3. Dear "egawa...",

    I found your pictures about the restoration work, it's excellent!
    We are making the same work on a BMW 700 coupé sport.

    Best regards from Argentine

    Fernando Raiteri