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Need advice on brake work


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#1 Rapom

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Posted 09 June 2019 - 09:41 PM

Im a mechanic for Honda.

With that said.. ive never messed with this hub bearing style brake setup with disc.. ive done plenty of re-packing bearings.. had a 65 mustang with drum..

Anyway ive ordered all around pads and rotors (went with titanium drilled rotors)

As of now the brakes suck.. as in car requires alot of pedal to slow down. And i feel like only right front is really doing anything.. rotors are original (116k)

Im assuming i may have to replace some lines and calipers.. hope not but it really doesnt stop well.

My reason for the thread... any tips? Will i expose any bearings and need to replace or repack them?

Side note: this is an 89 TSI SHP 5spd im going to be picking up 4 (full set) of of used SHP struts Wednesday seller claims they are in good shape... someone replaced my rears with bs struts and lowering springs and they torched the front shp springs... last owners were idiots. So should i wait to do brakes/struts/bearings at same time? Id rather piece it together as im driving it daily.. not because its my daily driver... because its fkin awesome and i cant believe i own one!

Thanks any tips/advice appreciated!





#2 markhansenconquest

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Posted 09 June 2019 - 10:04 PM

If car sat for a long time u should check to see if the brakes are sticking..............Pull the boots back and check piston to see if there smooth and move freely..................

Edited by markhansenconquest, 09 June 2019 - 10:09 PM.


#3 mikec

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Posted 10 June 2019 - 04:42 AM

StarQuest brakes are really quite simple.  You can do calipers, pads, and pistons without messing with the hubs too.  For rotors though you may be getting into the greasy innards.  Removing "e" clips allows the rotor to be separated from the hub with the wheel bearings and grease.

If the brake pedal travel is large before much of any braking action happens I'd look towards the master cylinder.  Under normal operation, when you press the brake pedal the sequence is:
1: power brake booster helps push on the master cylinder.  If the booster is bad, the brake pedal is much harder to press.
2: the brake master cylinder has two pistons.  The one closest to the booster is for the rear brakes; it gets the initial push from the brake pedal  As the rear piston moves, brake fluid pressure builds up in the rear brakes.  Once the rear brake pistons and calipers move enough to start applying the brakes, the pressure in the rear hydraulic line jumps up.
3: that higher rear hydraulic pressure THEN pushes on the front piston in the master cylinder.  The front piston starts shoving brake fluid to the front calipers.
4: if there is an issue with the rear brakes - e.g. a leak in the hydraulic lines or rear master cylinder piston itself then the rear hydraulic lines (and the region between the front and rear piston which is where the rear hydraulic hose connects) then no significant pressure ever builds up in the rear brake lines.  Ergo the brake pedal moves a fair bit but no braking action is felt.  Eventually the rear master cylinder piston moves enough to physically touch the front piston... further pushing of the brake pedal then makes the rear piston push on the front piston so you start getting front brake action.

A very common failure is for the seals around the master cylinder pistons to fail, especially the rear piston.  When this happens, brake fluid leaks past the seals rather than getting pushed into the brake lines so no pressure ever builds up.  Old brake fluid collects a fine silt from the atmosphere... this silt is like sandpaper to those seals.

If the car is driveable: on an empty road or just up and down your local street, get to 20 to 30 mph and apply the brakes trying to decelerate as you normally would coming to a stop sign or red light.  Don't stomp on the brakes, don't baby them either.  Accelerate again, stop again.  Do this 5 to 10 times.  Then park the car.  With your hand, see if you feel any temperature radiating from the brake rotors - BUT DO NOT TOUCH THEM OR THE WHEEL RIMS in case they are hot.  Just see if there is any heat evident.  If you have one of those temperature guns (with the red dots cats love to chase) use that to measure the rotor temps.  Ideally the two front rotors will be warm/hot and similar temperatures and the rear rotors will also be similar temps.  If one rotor is much colder than its twin on the other side of the car that's a bad sign - that brake isn't functioning.  If one rotor is much hotter than the other three then that brake is probably dragging - also bad.  No real temp in the rear rotors?  Think master cylinder.

When the master cylinder fails (those piston seals inside it) brake fluid will leak out, dribbling down the front of the power brake booster.  If you see wet/bubbled paint on the booster below the master cylinder then this is the first part of your bug.  You need a new/re manufactured master cylinder.

Other common problems - not unique to StarQuests: old brake fluid also absorbs moisture from the air.  Fresh brake fluid is a light brown color, almost clear.  Old and contaminated fluid is dark brown.  The moisture leads to rust forming on the caliper pistons at each wheel; that rust jams the piston so that brake doesn't work at all... but if you stomp on the brake pedal you might be able to get the piston to move and apply the brakes... but now the rust will jam the piston in this position so the brakes on that wheel stay applied even when your foot is off the brake pedal.  Rust also forms if the rubber seal between the outside of the caliper and the lip of the piston (this seal is a round bellows, similar to a CV boot would look like if you compressed it) gets old and rips/tears, letting water and road crud into the very tight gap between the caliper body and caliper piston.  Caliper rebuild kits include this seal plus the square cross-sectioned o-ring that seals the piston to the caliper bore against brake fluid pressure.  Not a difficult job to install.  You'll need a lot of spray brake cleaner too.  And emory paper to polish the caliper bore and piston surface to remove rust.  Don't grind away - just a light wiping should be enough.  If not, replace the caliper and piston.

If in doubt, whenever acquiring an older used car, I think it's smart to completely re-do the brakes.   Flush the brake lines, inspect the innards of the calipers and rebuild them (kits are cheap), replace the pads, resurface the rotors, and I'd even swap out the master cylinder or at least get a rebuild kit.  None of this stuff is expensive... and the brake system is critical to safety... and the brake system does not respond well to neglected maintenance nor a car parked for extended time.  Stuff rusts.

When removing the calipers, you'll notice the bolts that attach the calipers to the frames supporting the pads have rubber seals around them and there should be high-temp brake grease on those bolts.  The calipers actually slide on those bolts... so if they're rusted the caliper gets jammed.  Typically that results in one of the two brake pads wearing out rapidly rather than the pads wearing evenly.

The brake bleeding process similar to how most import cars are bled: start with "bench bleeding" the master cylinder before installing it onto the car.  I.e. fill it with brake fluid while it's gently held in a vice, use temporary tubes (included with most master cylinder rebuild kits or with re-manufactured units) to connect the output ports to the brake fluid reservoirs... then slowly push on the rear piston with a screwdriver until no bubbles come from the temporary hoses.  Install the master cylinder into the car.  Bleed the rear passenger side first (furthest from the master cylinder), then the rear driver side, then the antilock assembly, then the front passenger side caliper, and finally front driver side caliper.

Brake pedal adjustments: the pushrod connecting the brake pedal arm to the master cylinder is a long screw with a jam nut to lock it into position.  With the system bled and otherwise working properly, engine OFF, use one fingertip to gently push on the brake pedal  There should be a little pedal motion (a quarter to half inch pedal travel) before the pushrod even touches the master cylinder's rear piston - this "gap" allows parts to expand without applying the brakes as under-hood temperatures rise.  When the master cylinder is installed, there should be 1 millimeter gap between the rear of the piston and the end of the pushrod.  Measuring this fun... you can't do it with the master cylinder installed obviously as this stuff ends up inside it.  So you have to measure from the machined surface by the mounting bolts to the dimple in the piston, then compare that measurement to its counterpart on the power booster where the master cylinder bolts too (i.e. what the machined surfaces end up touching) and the tip of the pushrod.

mike c.

#4 mikec

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Posted 10 June 2019 - 04:50 AM

By the way: StarQuests have anti-lock brake function on the rear brakes only.  And the StarQuest ABS system is not like most modern car setups... it does NOT watch the wheel hubs to see if they are turning or not, lowering brake fluid hydraulic pressure if lock-up is detected.  Nope, nothing like that at all.  Instead, the StarQuest ABS is like a "smart" proportioning valve.  A "g" sensor detects the amount of decelerating the vehicle is experiencing (it's in the spare tire well - that silver box between the spare tire and rear seat backs), a sensor on the side of the transmission monitors the drive shaft speed (and thus the average speed of the two rear wheels).  The ABS computer looks at the rate-of-change in the drive shaft speed and compares that to the "g" sensor.  If the drive shaft speed is changing faster than the "g" sensor says the vehicle is decelerating the computer figures "rear wheels are skidding/slipping" and it reduces the rear brake hydraulic pressures.  That's it.  As long as the ANTI-LOCK dash warning light is OFF, odds are the ABS system is working okay... and it's very unlikely it's contributing to your poor brake performance.

#5 Turbo Cary

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Posted 10 June 2019 - 06:19 AM

Bleed your brakes and flush thoroughly. Also check to make sure your master cylinder isn't leaking. I have seen a ton of MCs leak on SQ cars. You could also have a brake hose concern. If they are original hoses replace them asap. 30+ year old hoses are no bueno.

I recommend deleting the rear ABS. Doesn't really work half the time and when I deleted mine I took it apart. The gunk and corrosion inside was insane. Made a big difference in pedal feel/stopping ability.

Re packing the bearings isn't hard to do and it would also be a good time to maybe throw a tack weld or two on the back of the front wheel studs as those are prone to slipping in their bores.

Edited by Turbo Cary, 10 June 2019 - 07:18 AM.


#6 Rapom

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Posted 10 June 2019 - 08:12 PM

Awesome thanks! So im new to this car. Very mechanically inclined. Il figure it out. Just really nice to get a heads up before going in. Replacing the soft lines is a good idea.. wonder how available they are. I definitely plan to fully flush system and clean n lube slide pins and check pistons for rust and leakage. Actually my brake light (not abs) was on this morning on my way to work.. my first thought was a slow fluid leak.. but the light went away and i checked the fluid when i got to work it was at the 3/4 mark.. mehh. As far as an abs light...im thinking previous idiots pulled some bulbs from the cluster.. i feel i should have an engine light (another day) but nothing.. no lights with key on. Im tempted to unplug sensors to force the cel on just to see it... same as abs (no way the abs still works) brakes dont work good enough even in the rain to lock the tires up even double footed in the rain. I really need to do my rear end and trans fluid too... cant believe im driving this and haven't even checked them... bad on my part! I did change engine oil day 1 even tho it was clear.(you never know) ive got SO much work to do! SO much. Need to get the shp wheels off to have redone/straightened. They were idiot owned. God how can people treat nitch cars so poorly!! You would all die if you saw some of the crap that was done to this quest. I need to replace ALL of the coolant hoses bad! Most are leaking.. ALL of them have bs aftermarket hose cutting clamps on them. Are oem or atleast direct fit hoses available? Only decent thing previous idiots did was replace underhood fuel lines with stainless braided lines (even tho its slightly ricer looking) but nothing tops my ricer fart cannon exhaust and the car being "stanced" its so low you cant even fit the tip of your shoe between the ground and the DESTROYED front lip! Oh and the ricer shift knob... yuck. Only good news i have is i took 2 oem radios and swapped chip sets untill i got one fully functioning oem radio! Ohhhh ricers hate oem stuff! Working on un-ricing this car

#7 Rapom

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Posted 10 June 2019 - 08:13 PM

Oh and i will spot weld the studs!! Great idea!

#8 BC_99

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Posted 10 June 2019 - 09:13 PM

There is a direct replacement stainless line kit on eBay for around $125 to replace all the soft lines. I’ve used that kit on 3 different cars. Good stuff for a great price. https://www.ebay.com...72bcaafc3545055

BC
Steering coupler replacement U-Joints are available here...
http://www.starquest...howtopic=145280

Posted Image Posted Image Posted Image

#9 mikec

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Posted 10 June 2019 - 10:02 PM

StarQuests do not have a CEL.  They long pre-date OBD-II requirements, even OBD-I.  The ECU does have a diagnostic output wire that can drive a voltmeter or LED but there's nothing on the dash to indicate if the ECU detects a problem or not.  Besides, the problems the ECU does detect are few and far between.  A few sensors completely non-functional basically.  The FAQ has an entry discussing the error codes and how to check them.  It varies depending on the model year of the car - or at least the model year of the ECU.  ECUs can't be swapped from just any model year car to another; only a few combinations are possible.  FAQ again.  There's very little advantage to swapping ECUs other than putting 88/89 ECUs into 87 cars if you plan on raising the boost level.  The electronic ignition modules however (aka "ignitors" and "ignitor box") are fairly interchangeable.  The larger metal-boxed ones used on 88-later cars tend to be more reliable than the smaller (deck of cards sized) black plastic ones used on 84-87 cars.  Again though there is little performance difference... just reliability.  Aftermarket ignitions (e.g. MSD) work on StarQuests too.  StarQuest fuel systems are best thought of as an "electronic carburetor" rather than a modern EFI system; the ignition system is independent of the fuel system (and the ECU for the most part) and is basically a late 1970s/early 1980s electronic ignition system.  Nowhere near as integrated as the modern EFI+Ignition found on cars from the last 2 or 3 decades.

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#10 Rapom

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Posted 11 June 2019 - 07:30 AM

What other than a vac leak would cause a high idle on these? My idle (hot) is anywhere from 900 to 1200rpm. Idles rough.. sputters randomly. I have seen it idle at 800 before but was running very rough. Cold idle is really the same.. it might be 1300.. then drop slightly after fully warmed up. Maybe i should have started another thread... i dont think this server has enough bandwidth for all the threads i need to start! Hahaha

#11 croquest87

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Posted 11 June 2019 - 08:59 AM

First things first.

I would do full compression test to eliminate big stuff.

Next I would check for vacuum leaks all over.
Next check the timing


Throttle body rebuild.injectors cleaned and tested  nose switch cleaned and lubed  tps isc re set is a must.New plugs  wires rotor and cap.

Fuel pressure test.

The basics to start with.




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#12 mikec

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Posted 11 June 2019 - 11:44 AM

A common cause of high and unstable idle is a too-tight accelerator cable.  There needs to be a bit of slack in the exposed cable close to the throttle body.  With the engine cold and idling, you should be able to push the cable down about a quarter inch without actually affecting the idle RPMs nor moving the gas pedal.  Otherwise, when the engine bay warms up and thermal expansion causes stuff to move, the cable gets too tight and holds the throttle open just a bit.  The end of the idle speed control (ISC) assembly (that stuff under the flat metal bracket at the side of the t-body, it includes the cylinder shaped park poking downwards and ending in a rubber bellows) is a small button switch known as the idle switch.  When that switch is closed by the throttle linkage being in the idle position, the switch grounds a wire to the ECU to tell the ECU the engine is in fact at idle.  The ECU uses the ISC to tweak the throttle opening as needed to adjust the idle speed.  When that switch is open, the ECU thinks the engine is NOT at idle and the car is thus "being driven" and it switches from "open loop" fuel control mode (idle) to "closed loop" using the oxygen sensor to manage the air:fuel ratio.  Adjusting the air:fuel ratio at RPMs just above idle leads to varying RPMs and unsteady idle.  If in doubt, look for the bracket that supports the throttle cable.  Loosen the two nuts that lock the cable to this bracket and let the cable slacken a ton.  If the idle stabilizes, that was your bug.

Vac leaks cause all sorts of problems too.  A can of spray carb cleaner sprayed at EVERY vac hose and air hose (including the fat ones from the air filter all the way to the throttle body) will help identify leaks.  Also spray around the intake manifold gasket, the base of the throttle body, etc.  StarQuests measure the airflow using the stuff inside the air filter... and air leaks after that Mass Air Sensor (MAS) confuses the ECU.  Even leaks around the lip of the air filter canister or where the MAS bolts to the canister lid cause problems.  Sloppy clips/clamps on the canister lid will cause problems.

mike c.

#13 Rapom

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Posted 11 June 2019 - 06:48 PM

Thank you!! All. So a few things ive already done. I had a dead misfire that was a fouled plug.

I should start a new thread... bwaah

But ive replaced plugs with cold ac delco. Im going to source the ngk 7031's asap.

I did run a compression test. Conditions were.. 80 ded f. Eng temp. Injectors unplugged (thoes have new connectors btw) unplugged coil wire. Throttle to the floor. I got 133-136 on all 4. (Is that good or bad? Ive not looked up the spec yet) consistancy is good.

Fuel pressure is right at 38-39 at idle.. no idea at revs. Idle is the issue.

The air box... yeeaaaaa.. rednecks cut a giant hole in the side.. A N D the lid does not fit well.. its canted off a bit with a tiny tiny gap all around. Clips do not seem to line up well with the corresponding latch..

Ive picked up the throttle pedal with my foot during idle and no change. I will check cable slack

I just sold a 95 suzuki sidekick that had all of the same issues and same idiot type if owners.. im very familiar with all of the sensors used back then.. had to replace almost all of then on the kick. AND the idiots adjusted the throttle plate STOP screw!! Hope this didnt happen on the quest!!!




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