disc brakes arent they great

[Fordmandan87]

disc brake issues

Well I had a day off and I got the ok from my boss at the dealer to work on my explorer. so wtih that time I installed disc brakes on the rear and now my pedal is low but it will build pressure if I pump like crazy. however the pressure bleads out. I have searched this topic and I have come up with a couple answers but no explaination that I found suitable. I was hoping that if I asked the question it woul be answered but the experianced. what difference does the proportion valve equiped master cylinder make over the non proportion valve master that they seemed to run on 95-01 explorers

 

[James909]

I just did the same swap with my Ex a few weeks ago. After I got all the brakes bled the pedal was very low like you described. As far as replacing the master cylinder goes if you want to get the absolute best performance I would replace it with one from a second generation Explorer because these master cylinders are designed for the disc/disc set up rather than disc/drum. Before you do that though, did you try adjusting the push rod that goes into the master cylinder? I am still running the stock master but I was able to get the brakes very close to perfect imo by adjusting this push rod. In order to adjust it just unbolt the master from the brake booster without disconnecting the lines. Then hold the push rod and back off the adjustment so it is resting further into the master cylinder. I backed it off to the point where the push rod was just about applying pressure to the brakes at rest. Disc brakes move more fluid than the drums so the second gen master would be ideal because it is designed to send the correct line pressures to the discs but I think once you get the push rod adjusted replacing the master won't be much of an improvement.

 

[Fordmandan87]

did yours seem to build up pressure when you pumped the pedal?

 

[James909]

Yes, it felt like it would build pressure if I would pump it but then if I released it for a second or two the pedal would be low again. This was before I adjusted it. Now that I've adjusted it the pedal seems to be a touch lower than it was before the conversion and it seems to rise if I pump the pedal. The pedal isn't dangerously low by any means it just takes a little getting used to. I don't know why it does this, my only guess is because you begin a stroke of the brake pedal again before all the pressure has bled off therefore you get pressure at the pedal quicker.

 

[Fordmandan87]

could I use a booster and master combo from a 95+
to firm up pedal

 

[James909]

Sorry it took me a little while to respond. But regarding your question, yes I believe you could use a master from a 95+ Ex. I know there are members on here that have done this swap so it's possible but I don't know how involved the swap would be because I don't have personal experience. You may have to bend the brakes lines a little because I think the connections might be in a different spot on the master. I don't think you would need the brake booster though I think you can use your current one. Before you do that though I would bleed the brakes again to make sure there is no air in the system.

 

[Fordmandan87]

to make my intentions straight i would be installing the booster too is to eliminate the guesswork of having the rod either too far out or in

 

[James909]

Please let me know how the brakes feel after you swap in a master/booster from a 95+. I may eventually consider doing this to my truck to complete the disc brake swap.

 

[Blacksheep Josh]

This is a writeup describing the entire process. From start to finish. I know a few of you have done this all ready, but at the end he describes how to adjust the feel of the pedal.

Good luck.

http://www.explorer4x4.com/discswap.html

 

[sn0border88]

I wouldnt both swapping the whole master, just get a prop valve and adjust it. It controls the amount of fluid sent front/back so both wheels see even pressure.

 

[beckhm1991]

Is there a Proportioning valve on the 91-94? I took my X into Les Schwab today and was told there is no proportioning valve, the master directly feeds the front and rears. Would you add the proportioning valve in-line? Thanks

 

[jd4242]

Isn't it in the rabs in the frame rail under the drivers side.maybe its bad try unplugging it,it will default to full pressure.I'm about to do this swap also so I hope you all figure this out in case I run into this problem too

 

[beckhm1991]

jd and Others...
First off, you were right, the proportioning valve is located on the drivers side frame rail. Second, the guy at Les Schwab seemed to think the 1st gen Explorer did not have an in-line proportioning valve but had one built into the Master cylinder, obviously not the case, will be calling him to share with him what I have learned.

Yesterday I spoke with a technician at Centric Parts (large brake component manuf.) and I told him what I had done, rear-end swap to 4.10 LSD and disc brakes, from 1999 Explorer, and that I was having rear bias issues, essentially brakes were dragging/binding up in the rear. He told me that this is due to preloaded hydraulic pressure that is present in disc/drum master cylinders. This allows the drum brake to do what it is supposed to once the brake pedal is engaged, without it, the timing of the rears in relation to the fronts would be out of sync.

He advised me to swap out the stock master (1991) for a 1995 Explorer master cylinder (part # 130.65044 w/cruise control or # 130.65043 w/o cruise control). Since I have cruise I went with the 130.65044. Planning on installing on Saturday, will bench bleed the master and put new synthetic fluid in, I always use synthetic with new parts on old rig. Will also bleed all lines too. I know that this has been a somewhat unresolved issue for many rear-end swappers out there. Once I have a few miles on the new master I will do a new and complete write-up on the rear-end swap, including the master swap. Have pictures from the rear-end job (Have done the front end too-much harder if anyone is interested in advice) and will also post pics from the master swap.

 

[jd4242]

What did it run you new?

 

[beckhm1991]

We have a Company in the NW called Olympic Brake Supply...they do ship and they have the best prices you can get. Typically they deal with Repair shops, not the general public. Paid $73.00 for the new one.

 

[beckhm1991]

Just to follow up and let ya'll know how the master swap went. I purchased a new master cylinder from Centric Parts #130.65044. I was told by Bryan, a technician at Centric parts to purchase a plug to bypass the ABS brake line which threads into the top of the master cylinder(my rig is a 1991, if you have a 93-94 with front ABS you will not have to bypass the ABS, will want to call centric and talk to a technician to be certain the 1995 master will work as designed). I will get the plug size later. I simply threaded the plug into the new master, removed the old master, bench bled the new one (must to this, will post how I did this later...really easy), set the threaded brake booster push rod to factory specs (0.985-0.950 inch, See Haynes manual), bolted the new master to the brake booster, threaded the old hard lines (Size M10 and M12) into the new master and bled the remaining air out of the master by having a partner depress the pedal and loosening the brake lines and than tightening the lines and releasing pedal...did this three times to get all remaining air out. You should not have to bleed the brakes at the wheels unless you suspect there is already air in the lines, I flushed my entire system to start fresh with new fluid and to ensure there was no air in the system. Entire process took 30 minutes and I was working slow...it was really cold. Will write quick article inluding necessary parts and tools with pics.

TEST DRIVE: I noticed right away that there was no brake drag, the car was rolling without any resistance, the pedal feel was perfect, right where it should be (stock position). The improved stopping performance was unbelieveable, after I did the initial rear-end swap (over a year ago) the initial performance over the old disc/drum set-up was impressive, but having the wrong master cylinder was creating hazardous rear-end bias (rears were biting too hard, very unbalanced brake feel), the new-set up is perfect. I have already driven on dry pavement, wet pavement and in snow. Performance under all conditions was perfect. I did hard stops from 60mph on dry and wet pavement and stopped on a dime, no lock up, rear ABS performed well and the car did not drift from center at all. In the snow I did a hard stop from about 45mph on a flat road and the brakes felt great, well balanced and the car did not slide at all...which it definitely did with the old master in place.

Final advice, if you do a rear-end disc brake swap on a 1st Gen. do not follow the advice at the end of this article regarding the adjustment of the master cylinder "Install the Tire and Wheel" http://www.4x4central.com/discswap.html, this advice will cause alot of problems...do not consider touching the push rod, the stock position is where is needs to be, otherwise you will have to fabricate a gauge to reset it. Simply buy the new master when you do the rear-end swap and you will be good to go. Any questions let me know. I am running a 4.10 with LSD in the rear (from 1999 exploder) and 4.10 up front...of course (came from 1990 Ranger 4cyl 4x4...hard to find).

 

[410Fortune]

Hello! Nice write up and info

I discovered this same thing a few years back, i have a 97 explorer 8.8 in my 88 bronco II
to complete the swap I used a 95 explorer master cylinder without ABS, without cruise control....that fixed the rear brakes, no more dragging (was using a set of pads in 4 months) ansd they performed well, I did however adjust the pushrod length from my booster... it is a tedious process (removing the master, adjust, re-bolt and test drive) but it did allow me to set my front/rear biast quite a bit.. 2 turns makes quite a difference!

I wanted my front brakes to lock up before the rear, the reverse was happening with just the master cylinder swapped.
I had removed my stock 1988 RABS years ago, I plumbed a hard line in place of the frame mounted RABS unit and removed all wiring and the brain.

my BII has explorer disc brakes at all 4 corners, I run carbon metallic pads with stock calipers and cheapo rotors, it stops AMAZING even with 35" tires

the rear discs gave me a MUCH better feel on the trail especially, when descending drop offs (ledges) or in rock gardens, or just manuevering downhill, I can literally watch my rear tire lock up/release, lock up release, which really allows me to control the trucks descent

thanks for the write up, wish I would have seen this sooner....

did you hook up the E brake cables to your factory floor pedal yet?
its simple

 

[beckhm1991]

In response to 410's comment about adjusting the pushrod length from the booster, I would highly advise against doing this, and so did the technician from Centric brakes (he had done alot of disc brake swaps, on every type of car, and what he shared with me is universal across most brake systems). Based on his advice, my knowledge, research and practice, all the pushrod does is set the point at which pushing the brake pedal will engage the master cylinder...i.e. the brakes. If you were to lengthen the rod (turning counter-clockwise), as I have done, the brake pedal becomes firmer, and if you over lengthen the push rod you can cause the brakes to engage without even touching the pedal, not a good thing to do, hence your brake pads wearing out in 4 months. If you shorten the length of the rod (clockwise) you will find that the pedal falls flat to the floor, because the rod is not reaching into the master to engage the brakes. Adjusting the brake booster push-rod will not affect the amount of front to rear bias, the only way this can be done is by installing an adjustable proportioning valve, the stocker is located under the drivers-side frame rail, it is an in-line valve that determnines how much line pressure is going to the rear brake lines. There is really no need to do this unless you have a specific purpose for controlling which brakes engage first, i.e. rock crawling. If you use your Explorer as a daily driver and weekend crawler you might want to install an adjustable prop valve, but if you are not that hard core, there is no reason whatsoever to make this modification. As I described in my previous post, using the stock prop valve in combination with the disc brakes and master from a 1995, my vehicle has handled and stopped exceptionally well under all conditions.

I have my e-brake hooked up, but it is definitely jerry-rigged, I have the intermediate cable from a 2nd gen which will make it work properly but I have not had the time to install it properly, if you have a simple way to do it or a good write-up I can refer to pass it on. Thanks

 

[jd4242]

So anyone going to do a new write up with pic and all new parts list to do this swap?