Nave43

Firstly i am driving a 93 Del Sol Si
D16A Motor swap
No brake mods
All wheel disc brakes
Valvoline Synthetic dot 3-4 fluid
Wagner Thermo quiet ceramic pads replaced 6/10/14 about 4k miles ago front and back.


While driving the pedal has slight travel but will hit pressure a bit under 3/4 of the way up and stop fine, but its still mushy past that point.
But when stopped the first half push of the pedal is no resistance. Then once you hit resistance its just mush and can be pushed to the floor with moderate force. Pumping them in this case doesn't do anything.

Stopping on a hill in neutral if i hold the brakes to the floor, the car will not move and the brakes do not loose pressure.

The car has steel brake lines which i inspected and they look fine
The rubber brake lines that connect to the caliper also look to be in good shape, no anomalies in the rubber, also didn't notice any bulges while bleeding.

I ran all the trouble shooting for the brake booster and to my knowledge its functioning perfectly.

The vehicle has has a mushy pedal for awhile now but is just now starting to get worse which is worry-sum. I am almost convinced its my MC but wanted to ask before i shell out $75+.

I just bled the lines yesterday and the old fluid was very foggy and dark brown. I bled the lines with Valvoline synthetic dot3-4 brake fluid. While doing so i noticed dirt and haze in the lines but by bleeding them so much its almost entirely new fluid in the system now. Bled the lines using the 2 person method and a piece of Vinyl tubing with a jar of fluid.

Although we depressed the pedal to the floor while bleeding so that might be my problem. Going to re-bleed today and see what happens.

dem0nk1d

it's the Master Cylinder.. look up behind the pedal assembly and look for fluid.

Nave43

Thats the thing there is no fluid leaking from the system. The MC stays steady full i have never had to add fluid.

I tightened the MC bolts today just to make sure... (My "Haynes" said that could be the problem)

Also i bled the lines again today with a vacuum bleeder and the pedal feels exactly the same. Some air came out but i blame that on having to remove both front bleeder screws. They were clogged so i cleaned them out with brake cleaner. Then removed any air i would have let in.

On the bright side with the car not moving and already on jack stands, it gave me a chance to paint the calipers

MisereNoire

Sounds like bad seals in the MC bore....you might also check that booster when you pull the MC for fluid having leaked INTO it. you can still have a functioning booster with brake fluid swilling around in it. You can opt to rebuild if you feel like it. not too hard a job.

Nave43

I will probably opt to try and rebuild the MC, 20$ rebuild kit vs 100$ new part. Anyone ever rebuilt one? Is it something i can f*** up terribly ?

And thank you for mentioning fluid in the booster. In all my research no one has mentioned that.

B serious

iTrader: (1)

Stop.

Check your caliper slide pins first. One or more of them is likely stuck.

Re-bleed throughly. Use a 1 man bleeder. The 2 man system has a big chance for miscommunication and error. Plus I hate everyone and I'd rather just do it myself. Have the car running while bleeding to move more more easily.

Nave43

The slider pins moved just fine when i changed the pads, Although i didn't completely remove them. Am i correct in saying they are the pins the caliper pivots on?

And i did re-bleed yesterday using the one man method, with the car off though to no avail. This is my first run in bleeding brakes though so user error maybe at fault.

B serious

iTrader: (1)

The pins allow the caliper to slide. It's a floating caliper. If the pins sieze, the non-piston side of caliper doesn't float toward the pads anymore as they wear and a larger gap between pad and caliper is created. Hence the mushy brakes and weird braking effort.

Wearing at an angle can be a sign of bad slide pins as well.

Check all the pins. They may have some normal initial surface tension...but beyond that, they should plunge in/out of the caliper bracket freely (with a little bit of grease film resistance).

Nave43

Thank you for the response, you always save the day B-serious

I will completely remove all the calipers and clean/re-grease the sliding pins on each and see if that helps my problem. Sadly though i have to wait for the paint to cure first or the tools and grease will F it all up.

B serious

iTrader: (1)

Good luck bud. The pins/re bleeding may or may not fix your problem. But I think it's a very likely place to start...plus its better to cross out the basics first.

Tyler Dirden

iTrader: (3)

The first time my pedal (delsol owner too) went mushy I replaced the MC. Bled it on the bench perfect with return lines, no bubbles. Put it on the car, never got a good pedal after a whole quart of new fluid pressure bleeding with help??????? Had to drive it home from the shop and just was careful. Next day, new MC and same sequence, no change. Drove it like that for about a month and SUDDENLY got a full pedal out of the blue while driving! WTF?
Converted my Delsol to rear disc last week with ALL new EVERYTHING. Bled it out for about the same time and same results????? Mushy pedal. While I was changing out the proportioning valve, I noticed that there is alot of traps that could hold air. These upward bends and downward attachments are all over the firewall lines. I suppose they are trapping some air that may eventually work through in a gradual way but have seen this trend alot on these cars.
Can't wait to feel what an improvement the rear discs make when they bleed out.

Nave43

Ive been seeing a lot of similar stories in my searches, not about it working all at once but no matter what people do there sol still has a mushy pedal.
I think there is something to you theory of the lines being ran in a less than ideal way.

Someone suggested gravity bleeding, starting the car, opening the MC and just letting it sit, then do the bleeding sequence. But dont pump the pedal just let gravity pull what it wants. this way air can escape from both ends of the system? Any input?


Agreed, also then i know its done.
Preventative maintenance if nothing else.

Tyler Dirden

iTrader: (3)

I think that brake fluid id heavy (thick) enough to pull some light air through a trap if flow was sufficient. I don't know what flow rate that might be.
I may try to push under pressure (like 5-10 psi) brake fluid through the MC line connections with pressurized dispenser. Then open the ports one at a time to blast through a volume of fluid that SHOULD flush every air bubble out. I will give this a shot next week at the shop and let everyone know how it goes.

Oaken81

I would just remove the 2 bolts holding the master cylinder to the booster and look for signs of brake fluid as already suggested.

Usually soft pedals are caused by worn brake components, air in the hydraulic system, frozen guide pins, leaks, bad master or misadjusted rear shoes if you have the drum setup.

Nave43

Definitely let me know how that works for you. ^

EGxBoostFiend

This works. You just have to make sure you don't run the reservoir dry and let air back in the system

Nave43

Thanks for the heads up "BoostFiend"

I finally got sum work done. Completely pulled apart the slider pins, and boots for both front calipers, gave them a thorough cleaning and new grease. They weren't frozen before hand but they do move better now. Didnt really help the problem tho.
(I had pictures but Honda-tech is being lame)

Checked my firewall on both side for signs of moisture... Bone dry

Acquired 2 free brand new replacement blank front rotors... cant hurt (Painting them w/ Hi-temp to prevent rust before i put em on)

My previous post about the pad wear being uneven was incorrect. I checked them all up-close today and they all seam to have even wear.

Going to do the rear calipers tomorrow and see what difference that makes.
and if that and a gravity bleed doesn't help then maybe i will unbolt the MC... Just trying to put off letting any more air into the system.

Lastly in my research i found that a 7/8 MC will bolt onto my stock brake booster for the 13/16MC that is on it now. Effectively giving me more pressure and less pedal travel. Maybe something that should have been done with Sols from the factory given there tendency of brake troubles.

Input?

Nave43

HELP!!!!1993 Del Sol Brake Problem | Page 2 | HondaSwap

^ Exact same problem... mostly all by Sol owners hence why i made this thread and didn't jump straight to MC replacement.


Secondly i am happy i haven't lubricated my rear sliding pins after reading many articles about the " Permatex Ultra Disc brake caliper lube " (Item# 24110) that i used. It as marketed as rubber safe, and Petroleum free but many people claim otherwise (Adverse reactions with Honda and Subaru) which has me worried. Many say it swells the rubber contrary to its packaging, I haven't seen it first hand but dont want to wait to see... I have to remove it ASAP and replace it with something better.

Sil Glyde, is the only thing i have seen mentioned that no one has had problems with. Problem is its only good to -20 degrees F, and there is at least a few days a year its colder than that here. Is there really no other option besides the 40$ Honda stuff?
I only ask because apparently not all silicone greases are safe for our cars... Whats about Shin-etsu, or Di-Electric grease on the sliders?

Sorry to get off topic but didn't think it deserved its own thread

Former User

Still soft pedal? If so, did you replace the MC yet?

Nave43

No i did not, but after reading so many threads (On this site and others) of people putting in entirely new brake systems on there Del Sols and still having the problem. It makes me wary of just throwing parts at it...

Former User

Soft pedal, no leaks --> replacing MC is generally the first step.

Nave43

I am not trying to argue that fact, you obviously know what you are talking about. My point is with so many people replacing the MC to no avail it makes me believe there is some underlying problem. My main dilemma is after days of research i still have no idea what that problem may be, or how to solve it. Only that i am not alone in my struggle. So while replacing the MC maybe the first step, if the replacement is in vain. Its just another dent in my wallet.

I do appreciate your help though, sorry if i am beating a dead horse...

Former User

You are over-thinking a basic brake issue, and it's paralyzing you from taking the obvious action. You need to prioritize. Replacing the MC is the next logical step.

Tyler Dirden

iTrader: (3)

Sorry that I didn't get back sooner with a result from pressure/flush bleeding the system. I have actually had the creeping improvement over the last week and now the pedal feels just right. Can not explain this though?????
Again, it happened before to this same car when I replaced the brakes and bled them out for maintenece purposes (I just got the car) and went through 3 MCs guessing it out. All of them were warranted and only cost the price of $30. bucks. The really funny thing that doesn't figure in is that the pedal was great before the brake change and fluid change.

I REALLY believe that pressure bleeding from the MC connections is an absolute foolproof way of flushing any contaminants and air from the system. It is just a matter of constructing a small low pressure vessel with a rubber line and clamp to connect it. Fabricating is my thing so no problem, but it may not be such an easy thing for some.
Good luck

bvblzr

Just bought a 93 D15 today with drum on the back. The guy said he just replaced the front brakes. When driving, pedal will be soft and at a light, will gradually work its way to the floor. If I drive it a distance, it seems to be much better, as it builds up pressure.

Thoughts?