Bkennedy's SAS and Rebuild Thread

[BKennedy]

I must have spent ten minutes on their site trying to get a match under $20. Thanks.

Called Fastenal and ordered two of the 4" bolts. They should be at their store ten minutes away by Friday, Monday at the latest.

 

[BKennedy]

Finally got time to pull the coil over shocks to see how they are doing. Besides the driver side having dirt and ATF in the threads and all over the inside of the coils from when my steering gear box blew, everything was fine. They are holding N02 and there is no obvious wear. Scrubbed down the coils, sliders and retainer with some Simple Green in a bucket. Sprayed, then wiped the shock bodies down with same. Coated everything with heavy duty silicone spray and re-installed.

I noticed it appears the passenger side, rear-upper exhaust manifold bolt is broken off. I can see the end of the bolt, minus the head. There is no exhaust leak, but why would a bolt break off by itself? I have never touched them because they don't leak. I am going to leave it alone because if it ain't leaking, don't fix it, but that is odd. Besides, I figure if I try to replace that one, I will end up breaking the rest of them off.

 

[Explorin'VA]

Those manifold bolts are a PITA. I cut my y-pipe out when I had the transmission off the truck but couldn't find any shop that would weld it back in place. This forced me to order a new y-pipe. When I went to remove the old y-pipe two bolt heads rounded on me, another sheared right off, and one came out easily. There are clamps that you can put over broken manifold studs that work pretty well. I ended up drilling out all the broken bolts and replacing with new ones...hope to never need to do that again.

 

[BKennedy]

It broke off right at the head.

 

[Rick]

I had one break on a stock 350 Pontiac for no apparent reason. In that case it did cause an exhaust leak.

 

[Kirby N.]

I broke one off on my explorer early when I owned it. I was trying to get the y pipe off for a tranny swap. Once it broke I stopped removing the manifold and tightened the rest of them back up. Mine never leaked the entire time I had my explorer. I always considered pulling it and welding a nut on it but never had to. I say leave it!

They break because of all the heat and expansion/ contraction. The manifolds are cast, so they expand at a different rate than the bolts stressing them.

 

[BKennedy]

Thanks, Kirby. I will leave it until it starts leaking or I can't stand the thought anymore of having a broken bolt on my Explorer.

I am still not happy with the brakes. I was cursing the soft pedal the whole time I was at Truckhaven. The pedal doesn't go to the floor, and it seems to stop on any type of terrain, but its soft and it bugs me. I was reading in this thread about brake master cylinders and such.

http://www.explorerforum.com/forums/showthread.php?t=424023&highlight=disc+brake+swap

I have posted in the thread before and wanted to know this (I don't like double posting, but if I can get an opinion, general consensus, or whatever, its worth it).

I have at the house, a 99 Explorer MC, and a 94 F-150 MC. Both have the same two-bolt mounting and bolt hole width:

Here is the break down

99 Explorer MC:
Cylinder Bore: 1.063" wide, 7-5/8" depth
Outer cylinder mounting surface: 1.571

94 F-150 MC:
Cylinder Bore: 1.056" wide, 8-5/16" depth
Outer cylinder mounting surface: 1.471

They are nearly the same width, but the F-150 MC has quite a bit more stroke. You can see in the picture, that it is taken up with the secondary piston (primary pistons are same length). 99 Explorer on the left, 94 F-150 on the right

A recap on what I am working with:

94 Explorer
1976 F-150 HP Dana 44, narrowed to Early Bronco width
T-Bird calipers with slotted/dimpled rotors
99 Explorer rear disc brakes
99 Explorer MC
94 Explorer booster
Everything is/was new at the time of the swap.

I was looking on some other off road and car forums about soft pedal feel after doing a disc brake swap, or upgrade. Several threads made mention of gutting the proportioning valve attached to the MC for the rear drum brakes and it working out for them. I am limited to a booster no larger than OEM due to my coil over hoops and the simple fact that I don't want to redo them. Winter (a engineer type genius guy who used to come out with us on runs before he got married, etc..) told me many years ago that the F-150 MC would help with soft pedal feel with a SAS.

Do you think the longer stroke of the F-150 MC will help with pedal firmness? And, I know it will fit onto my 94 Explorer booster, but will the pedal work with the longer stroke?

 

[Stic-o]

I was telling my dad about on the super dutys there is a difference in f250 and f350 brake systems the f250 uses a typical vacuum setup. The f350 uses a hydroboost system that uses the power steering system.

There is actually a off the self kit for Rangers for this.
http://www.powerbrakeservice.net/87rahypobrbo.html

 

[BKennedy]

Holy S*&t, that's expensive!!

 

[Rick]

I would get one of these to see how much pressure you are pushing to the calipers before making changes. With 4 wheel power disc brakes you aren't always going to get a firm pedal feel even though you are making enough pressure.

http://www.amazon.com/SSBC-A1704-Br...47033678&sr=8-1&keywords=brake+pressure+gauge

 

[BKennedy]

I was thinking that since I have the F150 MC, that I might as well try it. If it doesn't work, I will just swap it back out.

 

[jmdirk]

I was telling my dad about on the super dutys there is a difference in f250 and f350 brake systems the f250 uses a typical vacuum setup. The f350 uses a hydroboost system that uses the power steering system.

There is actually a off the self kit for Rangers for this.
http://www.powerbrakeservice.net/87rahypobrbo.html

That's sweet. But any hydroboost setup from a F350 should work. The MC mounting is identical on pretty much all Ford trucks.

I'm running a F250 MC which firmed up the pedal feel quite nicely and also put in a larger F250 vacuum booster to compensate for the loss in line pressure. The larger booster is basically right up against the wiper motor, but it fits

 

[BKennedy]

Could you measure the width and length (from the firewall) of that F250 booster? Also, are the brake line connections on the driver or passenger side? It's a very tight fit with the coil over shock and mount in between the brake line fittings.

Thanks for the info on the other thread as well. I'm glad I read this, I was just about to go replace the MC.

 

[jmdirk]

Could you measure the width and length (from the firewall) of that F250 booster?

Sticks out about 6.5" from the firewall. Diameter is about 11". Tough to get an accurate measurement.

There some pictures of it installed here:http://www.explorerforum.com/forums/showthread.php?t=424744

It just clears the wiper motor and the guard over the steering shaft

 

[BKennedy]

Sticks out about 6.5" from the firewall. Diameter is about 11". Tough to get an accurate measurement.

There some pictures of it installed here:http://www.explorerforum.com/forums/showthread.php?t=424744

It just clears the wiper motor and the guard over the steering shaft

Thanks. No way that would fit, the coil over hoop is 7" from the firewall, and 1" out from the OEM booster. When I replaced the booster, I had to cut down the studs and spread the hoops outward with my hi-lift. I wonder what a T-bird booster looks like.

 

[BKennedy]

 

[BKennedy]

Looked up the MC and booster on Rock Auto. The T-bird has a hydroboost model. Something to think about.....

[MENTION=28261]jmdirk[/MENTION] Also, now that I have your attention.....
After taking the MC's I have apart, I noticed the primary piston and the secondary piston are quite a bit different in length. I read your post about brakes again, and got confused. From what I understand, both pistons put out the same amount of pressure, but how is that possible with the different lengths of stroke? It seems to me that the primary piston operates the rear brakes and the secondary piston the fronts looking at where the brake lines enter the MC. However, having the longer stroke piston operate the smaller diameter calipers seems strange. Is that correct, or should I have the lines reversed so the secondary piston operates the rear calipers?

I also noticed that the longer I am out wheeling, the softer the pedal seems to get. You think getting some super duper brake pads, like Green Stuff would help?

 

[FR-425]

Your thinking volume not pressure. Bigger cylinder more volume. Bigger booster or more pedal pressure = higher pressure.

Proportioning valves change the flow rate which will also change the pressure but at the master cylinder the pressure is the same front to rear. The size of the bore and length of the piston is varied depending on how much line there is not so much about caliper size. Caliper pistons do not retract and so movement is tiny. Obviously this will change the initial volume but the only consideration there is the reservoir size. Once the air is out volume is not that critical.

And keep in mind the larger the caliper piston the greater force you get per PSI as it is a larger surface area.

I forget if you are still running drums in the rear?

If so I would think that your problem is back there. I know on mine before I swapped the rear to disk the pedal would drop and feel soft. The solution was to manually adjust the rears to reduce the volume going back there.

If the master stroke is to short it bypasses the rears which causes the large pedal movement and the mushy feel.

The start position of the pedal is important. The first piston in the master is the rear (closest to the pedal) So if you have too much play in the push rod you will not get full stroke and "starve" the fronts.

There must be pressure (adequate pressure) on the rear piston before the front will even move.

There should be NO play when the pedal is all the way up. In fact the manual says there should be some push-back on the pedal maintained from the master. ( this applies to drum brakes though) However I am still using the drum rated master and it works a treat.

Look at your disassembled masters. You will see that the the two pistons have a seal between them, an alignment pin and a spring. when you press the pedal it is the hydraulic pressure that is intended to push the other piston forward. If there is a problem however the first piston will compress the spring until it bottoms out on the second piston "mechanically" pushing it forward. = mushy pedal. You are feeling that spring not the solid static hydraulic pressure. Eventually when you really smash down on the pedal you will overcome that spring entirely and it will firm up but at this point you have front brakes only and may run out of stroke to get any real pressure. It's fail-safe but not optimal.

The stroke is also important in regards to the booster as it has a limited effective range. After it has moved so far it will bottom out and stop providing assist. You want the minimum amount of pedal movement possible before the brakes come on solid.

Make sense.? I think?

My point? I think you are fine with what you have, it's just a matter of adjustments.

Also I remember from earlier discussion about your brakes that the T-Bird calipers are tricky to get the air out in this orientation.
Did you ever rig up a power bleeder to be absolutely sure the air is out?

 

[BKennedy]

Thanks. It just seemed odd to me that the front brakes get the shortest piston, but that is not how they work. They work together. I have rear disks from a 99 Explorer. I have been constantly adjusting the rear proportioning valve and its better, the rig stops fine, I just don't like the soft pedal feel. I can't push it to the floor and when the engine is off, I can only push it down a few inches before it don't want to move no more. I noticed that the front pad outer shims had slipped out of position so the pad was not contacting the rotor evenly, so that might be part of the problem. I removed the shims altogether and took it for a ride. Better, and removing the shims doesn't seem to have any I'll effect. Then, I took Sarah's Ranger for a ride (its got factory 4 wheel disks). It has a softer than I like pedal as well but stops well. I think I will just leave it alone for now. Maybe get some super duper ultra *****in' pads.

Someday, it would be cool to do a hydraboost brake, along with Maniac's Saginaw PS pump swap.

So, onto other things. I have a few plans for the Explorer:

Needs new auxiliary battery. It can't take any load without dropping to six volts or less. DONE

Some cage work. Want to put in another X member in B pillar. Redo the windshield cross member so its higher, more effective and out of the way (I initially put it lower so i could still use the visors). DONE.

Thinking about tying the the cage into the frame but can only do it at the A and D pillars. B pillar is directly above frame, C pillar is welded to top of fender wells. You think its worth the extra work? Decided against.

While the seats are out, going to have them refreshed. On hold.

Will replace the cracked windshield so I can kick it out and make it easier to weld in the new cross member. DONE.

Maybe get a Ham radio. Still thinking about this.

 

[FR-425]

Thinking about tying the the cage into the frame but can only do it at the A and D pillars. B pillar is directly above frame, C pillar is welded to top of fender wells. You think its worth the extra work?

On this one I say no. As long as the feet of the cage are large enough to not punch through. It's over-kill to got too the frame unless you're run'n 100 mph.

If the cage fails it won't matter what it is attached to. Strong cage is more important than frame attachment. The body is not gonna tear off and if it did the cage would go with. yes?

Besides all you need to prevent punch trough is an interior cross bar on the floor at the B pillar just behind the front seats . If the floor pan folds the cross bar will push down to the frame rails.

On the Ex there is a lot of meat under the A pillar so I can't see punch'n through there. Large backing plate yes. Frame no.