[GoinManta]

OK bleed the Manta and drove to Springfield IL and back, brakes felt good, but there was still something not quite right about the pedal. It would still feel harder than it should at times, etc.. but the brakes themselves pulled striaght. Just figured it was a break in issue or the booster.

Was driving the Manta the last week.. and a odd behaviour started to occur.

Occasionally after light braking (gradual slowing down for a red light, or turn in a parking lot) the pedal goes soft and then a huge vibration and shutter hit the car (feels like it is from the rear). The the pedal is fine and it drives fine for a while, until it does it again. On a average trip it does it once, or not at all. Still have an intermittent pedal that goes between hard and normal.

New springs, shoes, drums were surfaced, new rotors, rebuild calipers (Although I have a feeling the driver caliper "maybe" sticking, it generates a LOT of brake dust...). New Master that has new seals.

Thought it may have been a loose ebrake cable, tightened it up and it didnt help.

Under hard braking the car is brakes striaght and solid. Under normal braking the car is very reliable and straight as well. Most the problems and odd behavoiur is when I am lightly braking or slowing down.

Any ideas?

 

[jlthunder]

Just a thought, did you put any lubricant on the "splash" shield on the rear brakes so the shoes slide correctly as stated in the manual? Did any grease get on the shoes/pads?

Jeff

 

[RallyBob]

Occasionally after light braking (gradual slowing down for a red light, or turn in a parking lot) the pedal goes soft and then a huge vibration and shutter hit the car (feels like it is from the rear).

Slightly leaking rear cylinder? Would account for the occasional soft pedal and the shuddering...brake fluid on rear shoes will cause some severe 'grabbing' issues..'til it heats up and evaporates. I'd at least inspect the rear brakes.

Bob

 

[GoinManta]

Thanks, I planned on pulling the rears and checking them again.

But figured I would get some ideas before pulling it apart, just in case the damn things look fine.

To be honest, I have never liked the Opel Rear brake setup. It was the #1 reason I came up with the Impulse swap.

Charles

 

[RallyBob]

Thanks, I planned on pulling the rears and checking them again.

But figured I would get some ideas before pulling it apart, just in case the damn things look fine.

To be honest, I have never liked the Opel Rear brake setup. It was the #1 reason I came up with the Impulse swap.

Charles

Later model Manta B's have a 'proper' self-adjusting drum brake mechanism like the majority of the cars in the world. I've seen a few people switch their early cars over to this system.

I personally like the manual-adjustment of the Opel drum brakes...must be the racer in me, since it allows for bias-tuning relatively easily, and eliminates the problematic self-adjusters. It also prevents me from being lazy and ignoring a low pedal!

 

[baz]

3 quick questions charles
1 whats the diff you feel between a "hard" pedal and a "normal" pedal as i want any pedal to be hard with just a touch of movement before it bites
2 have you felt round the wheels to see if you have one get hot to give an idea which wheel to start with
3 do you have a dail gauge you can use to check disks and drums for true with(to do drums mount inside out and turn)

 

[GoinManta]

Slightly leaking rear cylinder?

I had thought of that.. but wouldnt I lose fluid? I havent seemed to have lost a drop..

Charles

 

[GoinManta]

3 quick questions charles
1 whats the diff you feel between a "hard" pedal and a "normal" pedal as i want any pedal to be hard with just a touch of movement before it bites
2 have you felt round the wheels to see if you have one get hot to give an idea which wheel to start with
3 do you have a dail gauge you can use to check disks and drums for true with(to do drums mount inside out and turn)

Hard is hard.. the brakes engage with little travel on the pedal at all.

Normal, you go down a 1/2" or so.. not much and then they bite.

Normal they are easy to modulated

Hard is pretty much STOP and go...

Which has made me think I may have a pad that is seperating in the rear.

The Drums were turned and checked for true prior to carlilse, less than 2500 miles ago (Remember to the Rt 66 show it was 900 miles one way for me.. )

When I am not getting the behaviour, there is no vibration from the rear, so I would be willing to bet the drums are good.

Havent checked for heat.. will do that.

Charles

 

[yellaopelgt]

You did not mention new brake hoses....could this be an intermitent check valve effect from a hose starting to go???

 

[Killer Texas GT]

Charles when you had your rear brake drums turned did they re-acr the shoes to fit the drums? Also check to make sure you have the primary shoe to the front (smaller length of shoe surface). Like Bob said you my have small flulid leak or alxe seal leak getting on your shoes causing them to grab and schatter.

 

[gtjames]

I was thinking what yellaopel was thinking. I have had some crazy problems with those break hoses. I want to say expecially on Opels, but the reality is they are the only older vehicle that I really work on. So Im not sure if its an older vehicle thing as much as its an Opel thing.

 

[GoinManta]

New hoses (all three) so that isn't it..

As for the shoes, these all had the ebrake on them .. not saying the factory couldn't have gotten them backwards. They were new as well.

For now I am going with probably a fluid leak, just enough to contaminate the shoes, but not enough to noticeably measure in the reservoir.

Charles