HAVING SPONGY BRAKES

[94_PurpsRange]

Good afternoon gents (ladies too),

I have a 1994 4.0L XLT that I have been putting a lot of work into. Here is a list of what i have done over the last week or so...
Front brakes
Front rotors
Front brake lines
Front calipers
Front coils
Front shocks
Spark plugs
Wire set
Air filters
Fixed my broken air intake hose

I have a few other pending issues i need to address... First off.. My brakes are spongy and sink if in gear and held too long.. so i bought a new master for it and i hope it fixes that issue.
I have an ABS light on the dash and didnt even know i had ABS tbh... I couldnt find te ABS module under or around the master so i assume i have rear abs and the modeule is located somewhere on the firewall under the drive side? Not sure if thatsright... but i also have a acceleration issue of some sort?... it has no power really.. and going up an incline its a dog... flooring the gas pedal does nearly nothing... so im going to replace the TPS sensor today and see if that fixes it..

Can someone let me know if i am compleete off base with some of this stuff lol

 

[Uncle Gump]

94 will have RABS... located on the frame rail under the brake booster.

Brake pedal drift... I would take a hard look at the rear brakes. Sounds like a leaky wheel cylinder to me.

 

[Shran]

I would look at the RABS module where Gump said. I've had them leak very slowly and the brakes would fade just like you describe. I had no problem just bypassing it with a union fitting but then you don't have functional ABS... if that is a concern, you can clean the module/rebuild it or buy a new one. IIRC they were kinda spendy which is why I went the cheap route.

For your acceleration issue, try cleaning the MAF sensor first. If that is contaminated with oil & dirt it can have a profound impact on throttle response. Secondly, check your throttle cable for slack and remove it by adding zip ties, see this: https://www.therangerstation.com/tech/throttle-cable-mod/

The zip tie mod may help a lot - you push the pedal to the floor and think you're at WOT but really you're at half or less because there is so much slack in the cable.

Once you have ruled those two things out, look at the tag on your driver door and see what your axle code is. It will be a number and you can look here to match that with your axle gear ratio: https://www.therangerstation.com/tech/ford-7-5-8-8-inch-axle-tag-door-codes/

Higher numbers mean that your truck will feel faster from a dead stop than the same truck with a lower number. For example a truck with 4.10 gear ratio would feel like a rocket compared to one with 3.27's. You can swap axles or regear axles if you so desire but that may or may not be worthwhile. I own a truck with 3.27's and two with 4.10's, the former is really a turd and the latter two are pretty snappy but they run out of steam pretty quick.

 

[94_PurpsRange]

94 will have RABS... located on the frame rail under the brake booster.

Brake pedal drift... I would take a hard look at the rear brakes. Sounds like a leaky wheel cylinder to me.

So, I pulled the rears apart and everything seems to be in working order. BUT what I did find is that when I am bleeding the brakes (I do it wheel by wheel manually) the rear brakes have hardly ANY fluid coming out. like maybe a tablespoon worth. the drums are new as well as the shoes. the master in the truck is from the factory in 94. the booster seems to be working just fine... and if I have to come to a stop fast and hard the truck will lock up the tires and ill slide... so, I know I have some sort of an issue with the ABS..

so you think i have wheel cylinder issue?

 

[Uncle Gump]

A seeping wheel cylinder seal will cause pedal to slowly drift... and feel spongy.

You would notice wetness at the wheel cylinder. I pull the cylinder boot back and of its wet... it's leaking.

 

[94_PurpsRange]

I would look at the RABS module where Gump said. I've had them leak very slowly and the brakes would fade just like you describe. I had no problem just bypassing it with a union fitting but then you don't have functional ABS... if that is a concern, you can clean the module/rebuild it or buy a new one. IIRC they were kinda spendy which is why I went the cheap route.

For your acceleration issue, try cleaning the MAF sensor first. If that is contaminated with oil & dirt it can have a profound impact on throttle response. Secondly, check your throttle cable for slack and remove it by adding zip ties, see this: https://www.therangerstation.com/tech/throttle-cable-mod/

The zip tie mod may help a lot - you push the pedal to the floor and think you're at WOT but really you're at half or less because there is so much slack in the cable.

Once you have ruled those two things out, look at the tag on your driver door and see what your axle code is. It will be a number and you can look here to match that with your axle gear ratio: https://www.therangerstation.com/tech/ford-7-5-8-8-inch-axle-tag-door-codes/

Higher numbers mean that your truck will feel faster from a dead stop than the same truck with a lower number. For example a truck with 4.10 gear ratio would feel like a rocket compared to one with 3.27's. You can swap axles or regear axles if you so desire but that may or may not be worthwhile. I own a truck with 3.27's and two with 4.10's, the former is really a turd and the latter two are pretty snappy but they run out of steam pretty quick.

Thanks for the tips Shran! I will definitely be looking into the throttle cable slack and using some zip ties on it. Also, i have an axel number of R5 - L/S 8.8" / 3.55 gears. I will certainly look into possibly swapping out the rear end with a 4.10 but growing up in this truck and being the second owner (first was my grandad) ... something is off with the power... when going up grades it doesn't want to down shift and give any sort of effort... it does ok on the freeway but people behind me hate me while getting on... takes time to get up to speed... all the things I've read online (probably not great sources) is point to the TPS / Throttle cable situation... and since i already own a new TPS for it I figured I would give that a shot...

 

[94_PurpsRange]

A seeping wheel cylinder seal will cause pedal to slowly drift... and feel spongy.

You would notice wetness at the wheel cylinder. I pull the cylinder boot back and of its wet... it's leaking.

Ok I will pull them back off and take a look again and see if I can see any signs of leakage.

 

[94_PurpsRange]

Can someone tell me what is supposed to plug into this on the brake master?

 

[Uncle Gump]

Low fluid level sensor...

 

[94_PurpsRange]

ok... so.... the one i have in the truck is the same shown above except original from the factory.... It doesnt have anything plugged into it? .... i know i may sounds like a blasted retard here but is something supposed to be plugged into it?

 

[Uncle Gump]

Yes... if it's functional

 

[94_PurpsRange]

Yes... if it's functional

Ok so somewhere under the hood is the connector that plugs into this... I will get to searching. Z
Learn something new everyday.

Thanks Uncle Grump for the help..

 

[Uncle Gump]

Well... it may not be equipped.

It's possible that that particular master/reservoir fits more then that year... and some years have low fluid indicator.

 

[sgtsandman]

On the minimal fluid coming from the rear brakes. Are you getting a lot of air at first or is flow just poor, as in really slow?

Air would be a leak somewhere. Slow could be a clogged line or the RABS module is having issues.

The one part that is going to be hard to look at if everything else looks good is the brake line that runs along the driver's side frame rail behind the tank. Eliminate everything else before opening that can of worms.

 

[Josh B]

That line from the master cylinder goes toward the firewall
Of course it could change from 93 to 94 but you won't find many other examples since 93-94 are sort of in a group all by themselves