75 Brake booster upgrade to 80 booster?

[DNA Off Road]

Have 80 series brakes on 75 series. Replaced master cylinder with 80 series one. Seems to be lot of vacuum – brakes still do not perform that well. Machined discs and new pads all round.

Would it be worth changing the 75 booster for an 80 series one? Do they fit? Any other ideas/info appreciated.

[beanz2]

I've done this on my 75 series as I did not have the correct booster . The rod that attaches to the pedal in the 80 series booster is much shorter than the 75 series. I had to use a union nut and a stud to extend the rod so that the clevis can reach the pedal. I used a bearing and stud Thread Locker to make sure it doesn't loosen but I still check it periodically. Can you engineer this conversion in Aus?

The booster added little if any braking power however. Did you fit the rear disc brakes from the 80 series too? If rear drum brakes are still used and if the master cylinder is from a 4 wheel disc vehicle, the brakes will not work right.

BTW, did you fit 80 series front brakes to your 75 series diff or did you fit the entire 80 series diff?

Dave

[DNA Off Road]

Yes this conversion can be engineered. The swap was front and rear diffs, BTW I had rear discs on the 75 beforehand. I’m trying to work out where the issue may be without replacing anything else and finding out they perform the same as before.