Comments on brakes

[GLTHFJ60]

Once again, excellent thread. Tons of information here.

I wonder if anyone has used the pressure delay device successfully. How fast does it release full pressure? Is it measured in seconds or is it determined by the amount of pressure fed into it?

 

[ntsqd]

We used one of the LBS' on a much modified T-100 and it worked fantastic. I've no idea what drives the pressure rise rate.

 

[Mace]

My disillusion with "line locks" stems from the way that they are designed. To hold pressure in the system there must be electrical power applied. Loose that power and the braking function disappears.

Contrast that with the more expensive (though I don't really understand why) Mico-lock design. These use electrical power to engage the pressure holding mechanism, but the pressure itself is what maintains the seal. Stepping on the pedal without the electrics being turned on releases the brakes. This is a much better concept and design.

MICO, Inc. : Products/Literature
https://www.polyperformance.com/shop/Jamar-Line-Lock-p-74.html

Two easily found line locks that are not electric.

 

[ntsqd]

I have one of the Jamar products. Have never installed it. Got it for the dune buggy, but have never needed it.

Did you look at the prices for the Mico stuff?
The install isn't trivial either. Not difficult, just not trivial.

Both still suffer from the eventual leak-down of a hydraulic system. I don't think that should strike them entirely from consideration, just that some thought needs to happen about where and when to use them and when to do something else.

 

[Mace]

Yep and yep. The micro lock is way expensive. But it is not electric and they do work VERY well.

The Jamar is cheap and work okay, you just have to be careful how much you step on the brakes. Disengaging them when you press hard is pretty tough sometimes.

 

[ntsqd]

Yep and yep. The micro lock is way expensive. But it is not electric and they do work VERY well.

The Jamar is cheap and work okay, you just have to be careful how much you step on the brakes. Disengaging them when you press hard is pretty tough sometimes.

Some are electric. All but one of them that I have ever come across were electric. Saves having to plumb the brakes into the cab. The one manual unit worked much like the Jamar product, only more expensive and likely much better.
The Mico's are really built for uses like tow trucks. They're built for repeated industrial type use, which is why they're more expensive, but also why their quality is worth the price.

 

[FJ40Jim]

We used Mico-Locks on the tow trucks I maintained in a previous life. They always worked perfectly. Step on the brake, rotate the lever, and the truck was stuck good. I would not want to use one as a long term park brake, but it could be useful for winching.

 

[FJ40Jim]

Sizes of common brake components

Here's some additional info on Toyota Brakes that was scribbled in the margins of the brake catalog:
Standard disc FJ40/50/60 MC= 7/8"bore= .601in^2
2WD turbo mini or 1T MC= 15/16"bore= .690in^2
typical 88-newer 4runner MC= 1"bore= .785in^2

Standard FJ40/50/60 frt caliper= 2-1.338" pistons, 2-1.683" pistons= 7.25in^2
88- minitruck & runner caliper= 4- 1.683" pistons = 8.88in^2

Increasing MC from 7/8 to 15/16 is a 14% increase in hydraulic area
7/8 to 1" is a 31% increase in hydraulic area.

Increasing caliper from Cruiser to 4runner gives a 22% increase in hydraulic area.

Putting the numbers together:
Stock MC w/ runner caliper= 22% increase in pedal travel, w/ 22% less effort.
15/16MC w/ runner caliper= 7% increase in pedal travel, w/ 7% less effort.
1" MC w/ runner caliper= 9% decrease in pedal travel, w/ 9% increase in pedal effort.

The above comparisons reference the front brake circuit only. Any increase in MC size will increase the pedal effort required to get a given brake force at the stock rear brakes. So the 1" MC upgrade on a 60 w/ runner calipers and functional stock rear brakes will have approximately 20% increase in pedal effort and a 20% decrease in travel.

There is also a T100 caliper that will bolt to the Cruiser knuckle, but it is not a good fit on an otherwise stock cruiser because it is designed for a thicker rotor.

 

[miker]

Coleman racing sells a piston reducer kit for the GM Metric caliper. They come in 1", 1.125", 1.25", and 1.5" sizes. I purchased a set to try in my FJ40 with typical RDB conversion. They are not very expensive and look to be well made. However, there are two issues I ran into with these kits if anyone else happens to want to try them:

The first is that there is no dust shield or bellows for the new piston. This means that any debis like dirt, mud, water, small rocks, sand, etc can contact the piston and o-ring seal. This seem like it may eventually cause a failure of the seal.

The second issue is that the piston reducer design spaces the new reduced piston further out from the bore meaning that a caliper loaded with the reducer kit and new pads will no longer fit over the mid 90's GM truck rotor used on the typical cruiser RBD conversion. One option would be to mill or sand down the thickness of the pads. Just using my eyes, it looks like you would need to remove no more than 20% of the thickness so this is doable and still safe. Another option would be to find a thinner vented 6 hole rotor.

All in all this seems like a good approach but the application for these particular reducer kits is for racing. Without the dust shields in place to protect the caliper pistons I am reluctant to use these on a street and trail vehicle which is subject to a lot of dirt, mud, and water.

Racing and Car Products - Coleman Racing - Caliper Piston Reducer, GM, Metric, 1 1/2 Piston

 

[Fireman]

I wonder what size the mounting holes S 10 calipers are compared to the Monte Carlo calipers. The S 10 seems to have the 2 1/4" piston instead of the 2 1/2" Monte Carlo.

 

[ntsqd]

S-10's use the same D154 pads as the MC calipers and I understand them to be completely interchangeable with the MC calipers. What you'll need to watch for is rotor width. There are several rotor widths made, and the calipers must match or either the pads won't fit over the rotors, or there will be an excessive gap between the pads and the rotors. I'd call anything more than 1/8" total gap excessive, and even that might be too much.

 

[FJ40Jim]

I wonder what size the mounting holes S 10 calipers are compared to the Monte Carlo calipers. The S 10 seems to have the 2 1/4" piston instead of the 2 1/2" Monte Carlo.

A quick look at Rockauto shows the 1986 MC and S10 using the same 2.5" bore.

What year/option shows a 2.25" caliper for S10?

 

[dgangle]

Coleman racing sells a piston reducer kit for the GM Metric caliper. They come in 1", 1.125", 1.25", and 1.5" sizes. I purchased a set to try in my FJ40 with typical RDB conversion. They are not very expensive and look to be well made. However, there are two issues I ran into with these kits if anyone else happens to want to try them:

The first is that there is no dust shield or bellows for the new piston. This means that any debis like dirt, mud, water, small rocks, sand, etc can contact the piston and o-ring seal. This seem like it may eventually cause a failure of the seal.

The second issue is that the piston reducer design spaces the new reduced piston further out from the bore meaning that a caliper loaded with the reducer kit and new pads will no longer fit over the mid 90's GM truck rotor used on the typical cruiser RBD conversion. One option would be to mill or sand down the thickness of the pads. Just using my eyes, it looks like you would need to remove no more than 20% of the thickness so this is doable and still safe. Another option would be to find a thinner vented 6 hole rotor.

All in all this seems like a good approach but the application for these particular reducer kits is for racing. Without the dust shields in place to protect the caliper pistons I am reluctant to use these on a street and trail vehicle which is subject to a lot of dirt, mud, and water.

Racing and Car Products - Coleman Racing - Caliper Piston Reducer, GM, Metric, 1 1/2 Piston

I tried these also and had the same exact issues. See post 11 of the following link and pics below to see how I resolved the 2 issues of thickness and the dust bellows https://forum.ih8mud.com/40-55-series-tech/236372-rear-brake-lock-up.html

I bought the 1.125" dia reducers and they didn't solve my front/rear bias issue so I removed them. I probably went too small. When selecting I asked Coleman for recommendations and got a blank stare.

 

[Crawdad]

97 80 180,000 Brakes lock up after about 10 miles on freeway

I am looking at a 97 80 with 180,000 miles. The lot selling it just had brake pads all around, valve cover, plugs, wires, egr done on it.

When I first drove it, the brakes locked up after about 15 miles of driving on a low speed residential road. They towed it back and thought it was a bad caliper on the rear axle... they said they fixed it.

I drove it again today and was going about 70 on the freeway when a sudden vibration followed by the feeling I had just been attached to a large load of bricks came on. I could not coast, took 3000rpm's to go 10mph. I went 1/4 mile to get off the interstate and then noted that all 4 wheels are smoking not just 1.

Any thoughts, insights, advice on what could cause that, or if this is a "get out of dodge and run like ****" moment.... the dealer will fix it, just trying to figure out what to fix.

Any advice, info, appreciated.

 

[miker]

I tried these also and had the same exact issues. See post 11 of the following link and pics below to see how I resolved the 2 issues of thickness and the dust bellows https://forum.ih8mud.com/40-55-series-tech/236372-rear-brake-lock-up.html

I bought the 1.125" dia reducers and they didn't solve my front/rear bias issue so I removed them. I probably went too small. When selecting I asked Coleman for recommendations and got a blank stare.

Cool idea to fix those issues.
I'm surprised that you didn't notice any difference. That is puzzling.

 

[FJ40Jim]

I am looking at a 97 80 with 180,000 miles. The lot selling it just had brake pads all around, valve cover, plugs, wires, egr done on it.

When I first drove it, the brakes locked up after about 15 miles of driving on a low speed residential road. They towed it back and thought it was a bad caliper on the rear axle... they said they fixed it.

I drove it again today and was going about 70 on the freeway when a sudden vibration followed by the feeling I had just been attached to a large load of bricks came on. I could not coast, took 3000rpm's to go 10mph. I went 1/4 mile to get off the interstate and then noted that all 4 wheels are smoking not just 1.

Any thoughts, insights, advice on what could cause that, or if this is a "get out of dodge and run like ****" moment.... the dealer will fix it, just trying to figure out what to fix.

Any advice, info, appreciated.

All 4 brakes are locking because the master cylinder is slightly depressed. Probably a simple freeplay adjustment between booster and MC or between pedal & booster.

It's a simple adjustment, but the typical used car lot mechanic will have no idea what or how to do.

 

[VTCDN]

ntsqd ...

GREAT INFO AND POST .

DON'T STOP TRYING TO Give info.


What you say is word..

This is a common internet flamer of views.

I won't post my Licenses , But 12 I hold. Plus i get PAID to speak the way of Newton's Laws , plus..

CF's is 1000% of what you say of, If they watch F1 Racing , Brakes work at 1200 plus they just start.. (F1 car = 2 mill a car , Nascar= 5 grand a car going left)


Read and absorb , / enjoy .. GREAT so far NTSQD...


If they won't learn to get with the way of whats before and coming , PM me and move you to the DarkSide(private master's tech area PLUS) ( only for true dipsticks, Ill buy the import fee)

Great Post,



VT

 

[Mace]

MACE ,, Help here and learn the read.

VT

Huh??

 

[Crawdad]

Thanks Jim, found that the system now works properly after having the MC Freeplay adjusted and just for insurance and full flush of brake system.

I appreciate your input.

Crawdad

 

[ntsqd]

snip....

NT -
Using the area of one side on a 2-sided caliper & all of a single-sided really seems wrong.

I know that it does. It was something that I struggled with for quite a while and I still can't say that I understand it well enough to explain it. It has to do with comparing the areas of the opposing pistons of a fixed caliper vs. the piston(s) on a single side of a floating caliper.

Some confirmation, note the explanation under the first formula:
http://www.stoptech.com/tech_info/formulas _vehicle_braking_dynamics.pdf