Stock brake setup except booster?! (1 Viewer)

[DOGMARLEY]

1989 FJ62. After reading all the threads, I was wondering what would happen if I kept all brake components stock except changing the booster to a 4runner booster? So the MC and calipers/cylinders would remain stock fj62 spec. I saw the ratio thread, but multiple parts where interchanged. I want a normal feel...not too soft, not too hard, but just right. I'm really curious if changing just the booster to a 4runner booster will provide the same feel but more measurable (actual) braking force. Sorry for beating a dead horse and thanks for any info

Sent from my iPhone using IH8MUD

 

[bapmia]

I have an 89 FJ62 with all stock brakes except a 4Runner brake booster. I think the 4Runner booster resulted in a substantial improvement in the overall "feel" of the system. For me at least, the brakes felt more confident and more like those found in a modern vehicle (although still light years away from the brakes in my Golf TDI) if that makes any sense. Having said that, however, I think that properly adjusted and working drums make the biggest difference in pedal feel and the overall effectiveness of the system. I struggled with brake issues for awhile before I realized just how important functioning drum brakes are on these rigs. They are responsible for much more stopping power than you think!

By the way, here's the exact booster I used. Used a 20% discount code.

http://shop.advanceautoparts.com/webapp/wcs/stores/servlet/product_remanufactured-power-brake-booster-cardone_18690276-p?SID=skim3174X601276X3baf4c747914a9832f8b55c78d8e4f5e&cm_mmc=aff-_-cj-_-4022106-_-10711125

 

[DOGMARLEY]

Thanks for the info. My setup is all new and all Toyota including new calipers, cylinders, rotors etc. I need a new booster and can't decide between leaving it stock or going with a 4runner. Thanks for the link

Sent from my iPhone using IH8MUD

 

[LAMBCRUSHER]

I agree about the feel of the 4runner booster. all stock brakes fj62 with 4runner booster...you'll need to cut the pedal to booster rod about 1/4" off the threads, flip the runner booster 180 so its vac port is on top, get the donor vehicles check valve- oh wait, its already there in the 60/62(got one on my 55 as well...) you'll also need to adjust the booster to master push rod; mine had to go in alot. it'll clear a clutch MC in a 60 (or the 62 w/ manual like mine is) good junk yard mod/ butt saver. IIUC, 86-94ish are the golden years...might be 88-94- any early 90s model should bolt right up

 

[DOGMARLEY]

Great. Thanks for the install info.

Sent from my iPhone using IH8MUD

 

[DOGMARLEY]

Any special install steps or modifications with the 80series brake booster install? I am working with a broken foot, crutches, a toddler, infant, and an annoyed (but very understanding wife)! I still haven't decided between the fjz80 or the 4runner booster. They produce similar amounts of "boost" right?

 

[GeologistFelix]

No idea about the installation concerns, but I determined that...

1. The boosters for a '94 4runner and a '92 80-series both have the same (9.75") diaphragm diameter.

2. The FJ60 booster has an 8.75" diameter.

3. They all have the same bolt pattern.

4. At NAPA, it's $260 for a reman'd FJ60 booster, $240 for an FJ80, and $170 for a 4runner (the non-ABS version, of course). Odds are good that the replacement unit will be an Aisin (although they list both Aisin and JKC).

I'd get the 4runner one, myself. Diaphragm area (given the same overall design and configuration of valves/vacuum connection diameter, etc.) is the only thing that controls how much 'boost' a booster gives.

Just for reference, that inch of diameter difference accounts for a 25% increase in area. If you're replacing a worn out old booster, you're absolutely going to feel that difference.

 

[ntsqd]

Diaphragm area sets what the maximum possible boost is, but there is a valve of sorts internal that sets the boost vs. displacement curve. My understanding of vacuum boosters is that both sides of the diaphragm have vacuum applied while just going down the road. Putting your foot on the brake pedal causes the internal valve to partially vent one side of the diaphragm to atmosphere. The pressure differential created is what gives the boost.

How much is vented vs how far the pedal has been pushed is set by that valve. It is not necessarily linear, and it can be unique to any particular application. So two apparently identical boosters can have different valves inside them and behave totally differently depending on that valve.

 

[DOGMARLEY]

I read a few concerns about the MC leaking on (or into) the 4runner booster since it is rotated 180*...I don't understand how that can occur. Thanks

Sent from my iPhone using IH8MUD

 

[ntsqd]

When a m/c wears out the rear seal allows fluid to get past it, running out the rear of the m/c and into the booster. If the fluid fills the booster to the vacuum port before you figure out what is happening then it is probable that the engine will ingest some brake fluid.

 

[LAMBCRUSHER]

runner booster gets bolted on upside down so vac port is on top, you'll never leak that much fluid into the thing unless you are topping off a leakin res every few days or so without looking to see where it's going...hth

 

[DOGMARLEY]

Ahhhhh. That makes sense. Last question...would tire size have any effect on pedal feel after changing to a 4runner booster? I've seen a couple guys say they had better "feel" and less effort with their 35" tires, but I'm wondering if the pedal would feel to squishy with smaller tires like 31".

Sent from my iPhone using IH8MUD

 

[GeologistFelix]

It'd be even better with smaller tires.

Basically, the idea is that the stock booster, with big tires, feels like it's barely doing anything. The 4runner booster can put more force on the pads/rotor, so it works closer to how the system should.

 

[LAMBCRUSHER]

Ahhhhh. That makes sense. Last question...would tire size have any effect on pedal feel after changing to a 4runner booster? I've seen a couple guys say they had better "feel" and less effort with their 35" tires, but I'm wondering if the pedal would feel to squishy with smaller tires like 31".

Sent from my iPhone using IH8MUD

I got 31s on the 62 and the runner booster did give more "bite" not squishy at all. I think you get squishy pedal when you change the caliper/wheel cylinder volume-master cylinder stroke volume ratio...

 

[ntsqd]

snip.....
I think you get squishy pedal when you change the caliper/wheel cylinder volume-master cylinder stroke volume ratio...

I know that you can. Or get the opposite.

 

[CCRider]

Vac port on top?

I just mounted a new 4Runner booster with the vac port on the bottom, near its original location at the 5 o'clock position. It fits fine. I'm going to have to remove the original vac hose with the metal line in the middle and use 1 long piece of rubber hose instead. Length would be the same as original or slightly shorter. Any reason NOT to do it this way? The only reason I can see to mount upside down would be a shorter run of vac hose to the manifold.
I appreciate your thoughts.

runner booster gets bolted on upside down so vac port is on top, you'll never leak that much fluid into the thing unless you are topping off a leakin res every few days or so without looking to see where it's going...hth

 

[bullsheadcruiser]

Need to install new brake booster as old one hissing. So I need to bleed anything before taking off the master cylinder and will any brake fluid bleed?

 

[ad20k]

I just mounted a new 4Runner booster with the vac port on the bottom, near its original location at the 5 o'clock position. It fits fine. I'm going to have to remove the original vac hose with the metal line in the middle and use 1 long piece of rubber hose instead. Length would be the same as original or slightly shorter. Any reason NOT to do it this way? The only reason I can see to mount upside down would be a shorter run of vac hose to the manifold.
I appreciate your thoughts.

I have run mine like this for several years with no issues.

Need to install new brake booster as old one hissing. So I need to bleed anything before taking off the master cylinder and will any brake fluid bleed?

I was able to replace the booster by disconnecting the 4 bolts and pushing the master out of the way without having to break any of the lines. If you see fluid between the master and booster, that means you master has a bad rear seal and needs to be replaced.

HTH