86 4Runner build

ntsqd

Heretic Car Camper
Doh!! My bad. I'm forgetting yours is IFS. Where the offset issue pops up is in using these parts on a LA.
 

Grim Reaper

Expedition Leader
corax said:
I think I'll skip the JunkYard this time for this mod. AutoZone lists the calipers and rotors at ~$33 a piece + core for the calipers. By the way, thanks much for the info. Since you're upgrading the front brakes, you'll need to do the rears next, right?
full floater conversion w/ Supra disc brakes ;)
Actually I have a set of disc and calipers off the rear of a Trooper in a box for the conversion. $25 from the junkyard. :elkgrin: You need the Pins and hardware for that 92 as well. the pins for the 91 and older are not long enough.

Some more info. I'm kind of screwed at this point. AZ and the chain stores do not have a Reservoir to fit the 94 LC master. One of the guys that works at my local AZ was a Toyota dealer mechanic I have him looking for a reservoir or I'm junkyarding in the next couple days.

Another thing I found out is 5/89-1995 all run the same 1 inch bore master. Everything, LC, T100, 4 Runner, truck etc...all the same.
 

ntsqd

Heretic Car Camper
Interesting results from the spreadsheet. In actual mechanical * hyd leverage this new system (w/ 1" master) is lower.
Old (stock): 63:1
Old (13/16" m/c w/ new calipers): 70:1 (No wonder it stops well!)
New (1" m/c): 47:1

The fly in the ointment is the booster. My recomendation (based on the known to only be partly accurate parts books in my library) would be to use the '92's 15/16" bore master (53:1).
I'll venture that the '92's booster diaphram is slightly larger, or that the 92's brake pedal has more ratio than the earlier trucks (my '84 = 4.4:1).
 

Grim Reaper

Expedition Leader
ntsqd said:
Interesting results from the spreadsheet. In actual mechanical * hyd leverage this new system (w/ 1" master) is lower.
Old (stock): 63:1
Old (13/16" m/c w/ new calipers): 70:1 (No wonder it stops well!)
New (1" m/c): 47:1

The fly in the ointment is the booster. My recomendation (based on the known to only be partly accurate parts books in my library) would be to use the '92's 15/16" bore master (53:1).
I'll venture that the '92's booster diaphram is slightly larger, or that the 92's brake pedal has more ratio than the earlier trucks (my '84 = 4.4:1).
WOW that much of a change for 3/16's of diameter?

Thats what I was worried about. I wanted a softer peddle. Just too much travel with the 13/16. Feels like it is nearly at the floor. :(

Is the 15/16 a 4cyl spec? Cross refferencing on Advance auto parts website the part number I have is shown for all 89 up to 95 6cyl trucks without ABS.

You are figuring the piston surface area verses the master diameter to get that? Does that figure in the 7/8's rear's or just the math for the front?


Maybe it won't be too bad since the larger calipers will have more friction surface. I guess we will see. If it is to much I will have to start looking for a 89 v6 4Runner booster. That will be a bolt up and the first of the 1 inch masters.
 

ntsqd

Heretic Car Camper
All based on piston area, which has that pesky exponent in it and is why it has such a large effect. The booster is a bad enough complication (rare is the race car with one), drum brakes' servo-action is not something I've ever had any math modeling education on.

Though I doubt in this case it would work against you, keep in mind that apparently identical boosters from different applications can have different boost vs. pedal effort curves. The booster for Mom's grocery getter Pontiac 4 door may look the same as the one on the GTP, but the performance curve of the internal valving will be different because of the different nature of the use of the car. I would expect that a 4rnnr's booster to have a slightly more aggressive boost vs. pedal effort curve than one for a truck due to the expected type of driver. So if the 4rnnr booster proves to be have too low pedal effort for your taste, one from a truck might be closer to what you're looking for.

FWIW I've found a lot of good brake info in this book: http://www.cartechbooks.com/vstore/showdetl.cfm?DID=6&Product_ID=2923&CATID=3
 

Grim Reaper

Expedition Leader
I had not looked at the truck on the booster to see if it spec’s any different. Advance Autoparts site has a feature that show what it fits.
Plugging in a 1989 4Runner that booster fits 89-93 4Runner 89-95 truck 93-94 T100.

Might be time for a Junkyard run for the booster and reservoir.

Funny but my Booster may have a problem. I managed to stall the engine at idle pumping the brakes rapidly.

I guess I'm in with both feet at this point LOL.
 

Grim Reaper

Expedition Leader
Made it by a junk yard today and had to buy a whole used worthless master cylinder to get the reservoir. The lady at the desk wigged out when I just set the reservior on the counter.

"Where the rest?" she asked me.

"in the truck its worthless as anything except a core. Its so full of crud from lack of service its absolutely not usable."

Paid the $20 for the "master" and left with the reservior.

Decided to try the stock booster for a while becasue I need the truck back on the road.

I was worried that the truck was going to have a really hard peddle. Its definitely a little more firm but not horrible. Pads and shoes are not even close to seated yet so we will see how it does once they get burnt in. If I hammer them I can get it to stop pretty good.

If its still too much peddle I'll start looking for a booster.
 

ntsqd

Heretic Car Camper
This is the part about brake mods that always makes me uneasy. I wish that I could say "use X calipers, Y booster, and Z m/c and all will be good." Since they are a system that is designed as such, mods have to consider the whole thing. When race type parts and OE type parts are in the mix is when things get really interesting......
 

ntsqd

Heretic Car Camper
FWIW my experience with ABS in the dirt has resulted in the universal advice to pull the fuse! Fortunately this vintage doesn't have that complication.

What we found when I was working at wilwood was that if you increased the front brake torque that you had to increase the rear too. Mods are reasonably possible, but you have to maintain the front to rear balance (Not Bias) within a fairly small window.
 

Grim Reaper

Expedition Leader
ntsqd said:
This is the part about brake mods that always makes me uneasy. I wish that I could say "use X calipers, Y booster, and Z m/c and all will be good." Since they are a system that is designed as such, mods have to consider the whole thing. When race type parts and OE type parts are in the mix is when things get really interesting......
Its a gamble but after looking at what I did and the cross referencing I basically put a 92 brake system on except the booster. The rear brakes spec out about the same and the master id delivering more to both ends so it seems to have stayed balanced.


As for ABS....its for people that can't drive. I HATE it.

GM ABS is the worst. I keep unplugging it on my company trucks. The 95 Van I drove for a while it twice almost got me in a accident. It was single channel system. Any wheel locks it backs off the pressure on all wheels. Once I was exiting the hwy one back wheel was on a little dirt right on the white line and it released the front brakes as I was coming to a stop when the right rear locked. Almost shot out into traffic.

I pulled into the next gas station and unplugged it.

About 6 moths later on the other side of the bridge from the first time it almost got me I had a girl blow a red light. I slammed on the brakes and honest I felt I had plenty of time to stop. All of a sudden the peddle starts it vibrating and drops to the floor and it felt like I was on ice. From 30 mph I could not stop the truck till I had completely clear the intersection. That speed I should have been able to stop in 1/3 the distance.

Seems the previous service on the truck some doo gooder mechanic noticed the ECM under the hood hanging on the side of the master unplugged and hooked it back up for me in a attempt to kill me. I went strait to the dealer and raised immortal hell! :ar15:


GM has been sued multiple times over that crappy ABS system.
http://www.theautochannel.com/news/date/19961004/news02126.html

They like to blame the wheel sensors when its really a problem that its single channel instead of each wheel being on its own channel operating independently. It comes down to single channel is a LOT cheaper to make but it gives people a false sense of security becasue under many conditions it actually makes stopping distances increase..

This is more like what I have experienced in this one.
http://scout.wisc.edu/Projects/PastProjects/NH/96-10/96-10-03/0020.html
 

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