Brake Booster - Master ADM - JDM

[Ozdunker]

Car - AE86 ADM with jdm 4ag. front & rear discs

Brake Booster - Master cylinder

Problem - Had to replace faulty ADM Aisin brake booster and master cylinder. The replacement was with JDM Nissin booster and cylinder. Issue is now Brake pedal is now extremely low and wont come back up after pressing. So low the rear brake light is on.


Are there issues to switching over to the JDM parts?

Are there any adjustments to increase brake pedal height or any other causes or just requires another re-bleeding?

Anyone who has made this change?

Options/info on replacement Brake Boosters might be useful for other posters.

Thank you.

[Jimmee1990]

I always find the back of the car needs to be higher than the front to bleed the master properly, builds up a small bubble in the end of the cylinder otherwise.

The parts are all directly inter-changaeble, so there's either something wrong with the new cylinder or it's a bleeding issue.

[Ozdunker]

Thanks James, will give that a go.

[LittleRedSpirit]

There is a pedal height adjust as the connection ot he pedal arm is adjustable. Theres a 14mm nut that locks the centre shaft of the master cylinder/booster system off, which can be loosened and pedal height adjusted.

[Matt]

If you can bench bleed the master too by getting old fittings and bending it so it empties back into the reservoir.

[Hen may possibly be a nut]

Maybe I'm a little slow, but it always seems like I need to bleed brakes way more than I expect before the pedal comes good.

[Ozdunker]

Thank you, nothing has happened as yet. The car is at my mechanics place and he had to go have some minor skin cancer surgery and is then going away for another week. Very frustrating as I don't have access to my car at the moment. I will update.

[Ozdunker]

Finally some action. However now the brake booster wont release the brakes. The brake pedal actually goes down when the car it turned on.

Without the vacuum connected no booster, with the vacuum connected booster works and wont stop working.

Now driving around with no brake booster.