Modified Brake systems?

[Bayside]

Has anyone on here modified their braking system and what were the results?

I have seen many posts regarding different pads and braided lines but none discussing alterations to the brake booster or master cylinder to gain more mechanical advantage. I found this article and it got me thinking about ways to improve the Gen2 braking and what parts from other vehicles could be used achieve it.

http://home.4x4wire.com/erik/4runner/brakes/

Having started my 1UZ conversion and considering a supercharger system brakes are one thing I dont want to find lacking!

I realise that the bigger the tyre the more leverage on the braking system therefore effectively reducing the strength of the brakes and increasing the effort to use them. I run 33's at the moment and as predominantly a road car wont go any bigger.

I am considering a slightly smaller 15/16" master cylinder from a corolla or similar to regain some advantage and offset the tyre effect. This coupled with some EBC pads with more bite and braided lines should go some way to assist.

Modern systems use brake assist which I assume increases the vacuum at the diaphragm to increase braking power and reduce effort at the pedal I need to research a little more but wonder if a system from a more modern vehicle ie its vacuum and diaphragm system would retrofit. Another option would be to ry to increase the vaccum at the existing diaphragm to increase the assist.

Thoughts and experiences please

[NiftyNev]

You want to use a smaller bore master cylinder? You are on the wrong track to start with, so I think you should leave the brakes alone.

Nev

[Bayside]

The reason Ive posted is to learn more before potentially making a mistake and to find out what works or not and why - everyone has a starting point being told to simply leave alone does nothing to further anyones knowledge or move forward, if no one shared what they knew we would eventually come to a grinding halt or make costly mistakes that otherwise could have been prevented and a large element of what forums are about would be lost!

Rant over back to the matter at hand.....

I may have read the theory wrong on the linked write up - in which case a correction to my mix up will be constructive and welcomed.

Where I have become confused is in thinking that a higher hydraulic ratio ie 7.5:1 would be better than a smaller figure say 5.5:1 but having read it again Im unsure and a bit confused?

I thought that the smaller master cylinder piston size gave better leverage despite reducing the ammount of fluid moved (too small being unable to move enough so a balance needs to be achieved) and therefore more shove at the caliper end lb for lb at the pedal. The opposite to this being that the larger the Master cylinder piston the closer that the lb pressure at the pedal is to the lb pressure at the Caliper - much like gearing?? Help!

[Bayside]

Taken from Wikipedia

Two hydraulic cylinders interconnected
Cylinder C1 is one inch in radius, and cylinder C2 is ten inches in radius. If the force exerted on C1 is 10 lbf, the force exerted by C2 is 1000 lbf because C2 is a hundred times larger in area (S = πr²) as C1. The downside to this is that you have to move C1 a hundred inches to move C2 one inch. The most common use for this is the classical hydraulic jack where a pumping cylinder with a small diameter is connected to the lifting cylinder with a large diameter.

So I think the theory in my mind is correct but the application may need to be rethought. Smaller Master cylinder willl give longer pedal travel but more effort.

[tonupteabag]

From what i can gather you will need to push more fluid from the master cylinder to get greater effect at the caliper. so a bigger master cylinder bore will push more fluid creating more pressure at the back of the piston giving more effort at the wheel than exerted at the pedal. If i read it correctly plus you need to get the front to rear load balance spot on or it can cause problems under heavy braking.

[BUSHWHACKER]

Well maintained standard Surf brakes work very well.
The 1UZ engine is about two thirds the weight of the diesel and it creates a stronger vacuum, so you've gained a bit more braking force already. Just fit braided lines if you want more 'feel' when you press the pedal.
If you're thinking of a supercharger, then it's the drivetrain that will want beefing up.

[Wolfracer]

It always makes me smile when someone says more power means you need better brakes...

Example. A standard surf doing 70 on a motorway vs a Supercharged surf doing 70 on a motorway. One with 130bhp, the other 300bhp...
THEY WILL BOTH STOP IN THE SAME DISTANCE!
That is unless:
a) you brake and continue to press the accelerator at the same time
b)You like travelling at supersonic speeds on twisty roads and need brakes that'll pull you up very sharpish, there's really not much point.

Remember you are in a 2 Tonne Bus...

[tonupteabag]

This is why i like it here....

[TonyN]

Stomp on your brakes, if you can lock the front wheels then all is good and go and do something else.

We fitted a Landcruiser Master cylinder to Andylalas truck, it has a bigger bore so shifts more fluild for the same distance of pedal travel and he liked it. But his 2nd Gen did weight in at over 3000kg's after he'd finished with it.

But I'd go with Vince, decent pads and a well maintained system and what you have will be fine.

Most dull brakes on Surfs are because of a siezed calipers or out of adjustment rear drums.

35's and up make the brakes feel less stoppy due to the leverage, and slow offroading in an auto when you're on the brakes alot will cause fade as they heat up. But you're not in that territory.

[Toyo]

Hi there.
Long time no posting on this forum, sorry!
What TonyN says is right, you can use a LC HDJ 80 Master Cylinder, what have to be "plug & play" as I read in yotatech.

What do you think about swap the rear drums to discs. I'm studying the possibility to use LC KDJ rear discs with any kind of caliper which attach properly with the hand brake, off course, have to make a bracket...

I'm thinking this because I'm wearing 285/75 R16 on my Runner but for the moment this is only an idea, have to check pieces on a scrapping yard

[NiftyNev]

As far as I know the latter 130 series 2.4 Surfs and the 3Ltr have the same master cylinder bore as a LC HDJ 80 Master Cylinder so what's the point in changing it?

Nev

[TonyN]

As far as I know the latter 130 series 2.4 Surfs and the 3Ltr have the same master cylinder bore as a LC HDJ 80 Master Cylinder so what's the point in changing it?

Nev

Not sure what LC it came from, Andy bought it. Was noticably bigger when I saw it on the truck, I don't think I actually fitted it for him as I remember phone calls from him about having trouble bleeding it.

Looking back it was a 3rd Gen one he fitted, which he said was inbetween an 80 series (which didn't fit a 2.4 because of the turbo heat shield) and a 2nd Gen surf one internally??

I'm still not sure its worth the effort for a truck that is pretty standard weight.

[Albannach]

I love this type of thread. There is an extremely complicated and technical answer, but that matters not a jott.

Nev and Vince are both 100% correct.

[NiftyNev]

Forget about an upgrade except maybe a disc brake rear. The braking system, as it is, is fine if you service the lot. This includes rebuilding the calipers, not just new dicss and pads. You WILL notice a difference if you do this.

Nev

[Toyo]

Hi there..
This is what i found, it's for a USA 1st gen Runner, but I think it must be the same for a 2nd gen...

I think, it could be interesting..

http://www.ultimateyota.com/index.ph...64640#msg64640

(This is a copy & paste)

time to upgrade the Master Cylinder in preparation for my T100 caliper swap - the bigger pistons on the T100 calipers need a slightly bigger MC bore. The '90s T100 1 tons have a 1-1/16" MC bore vs the popular 1" bore found in many mid 90's 4runners and LandCruisers - bigger isn't necessarily better when it comes to the MC bore. A bigger bore moves more fluid, but produces less hydraulic pressure with the same amount of force on the pedal. In this case, I wanted to match what was available on the T100.

here's my $50 ebay master cylinder, brand new - note the 1-1/16" cast on the side


out with the old 7/8" bore MC



in with the new (and the aluminum looks much prettier than rust greengrin)


it was a simple bolt on swap, no drama. The front brake line needed to be bent a bit to match up with the T100 MC port. I didn't bother to bench bleed it, prefering to do it on the vehicle with a rag under the lines. Initial driving impressions are good with pressure building and the pedal firm very near the top of it's travel, though when I get the T100 calipers on it should soften up a bit. I would not recommend this size MC with the stock 1st gen calipers as it could get tiring to drive with the extra firm pedal. On a 2nd gen with the "S12W" calipers though, it might be a nice upgrade that would give a better pedal feel.

I cannot personally vouch for this cross reference:

Brake Master Cylinder for the following 1 TON Models:
1994 Toyota T100 Pickup : 4-2694 2.7L DOHC
1994 Toyota T100 Pickup : V6-2958 3.0L SOHC
1995 Toyota T100 Pickup : 4-2694 2.7L DOHC - Notes: w/o ABS
1995 Toyota T100 Pickup : V6-3378 3.4L DOHC - Notes: w/o ABS
1996 Toyota T100 Pickup : 4-2694 2.7L DOHC - Notes: w/o ABS
1996 Toyota T100 Pickup : V6-3378 3.4L DOHC - Notes: w/o ABS
1997 Toyota T100 Pickup : 4-2694 2.7L DOHC - Notes: w/o ABS
1997 Toyota T100 Pickup : V6-3378 3.4L DOHC - Notes: w/o ABS
1998 Toyota T100 Pickup : 4-2694 2.7L DOHC - Notes: w/o ABS
1998 Toyota T100 Pickup : V6-3378 3.4L DOHC - Notes: w/o ABS