Anemic brakes in '91 with LS3 engine swap (1 Viewer)

[callmeDW]

As stated, super soft braking power - I'm the new owner of a '91 FJ80 the PO dropped in a 5.3L LS3 engine among many other upgrades.

But the brakes totally suck - local Toyota mechanics (great reputation in Wilkesboro, NC) -- we had evidence the LSPV valve was bad, replaced that - bled the system and ensured we were finally getting fluid to all 4 corners. But the master cylinder indicated it was bad - so they replaced the master then the booster. Bottom line, we're sitting with a little better braking power but still pretty anemic.

Suspicious of the vacuum setup off the LS engine - does anyone have some specs we could measure against to chase if we're getting too much / not enough vacuum pull? The master and booster are OEM spec to the FJ80. Next would be swapping out front calipers. Just trying to gather some info to pass along to the shop - any help / experience is greatly appreciated!

 

[NeverFinis]

Does the LS motor have a cam? Is the engine lopey?

I have a L96, completely stock, and it produces enough vacuum for the booster. Google search shows spec is 18-21 inHg.

Relevant Thread: Need opinion on brake issues Land Cruiser 80 LS swap, second posting. - https://forum.ih8mud.com/threads/need-opinion-on-brake-issues-land-cruiser-80-ls-swap-second-posting.1342461/

 

[White Stripe]

Did you bleed and adjust the lspv to the proper caliper pressure?

 

[ppc]

Have you checked all of the rubber brake lines. One or more of the rubber lines could be breaking down and ballooning reducing pressure and also feel spongy.

 

[robnicko]

really nice looking 80 !!

Have the rotors & calipers been upgraded to the later FZJ80 type or still 1991 fj80 spec?
theres a big difference in braking power with the later equipment predominantly the rotor diameter / size