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  #1  
Old 10-22-2012, 08:41 AM
JamesDean's Avatar
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Location: NE Ohio
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Brake Pedal Lacks Firmness. Not sure what next to do...

Hey everyone,

I thought I had a thread on this topic but evidently not.

I've been trying to chase down my brake pedal feeling crappy for a while now. Compared to my 300D (all stock, with stainless steel lines) the 190E's brake are utter crap, in terms of pedal firmness. With about 1/4 or less of pedal travel on the 300D, I am met with a nice firm feeling. On the 190E I don't get this firmness.

Brake Setup:

190E Master/Booster. Master is new.
E420 Front Calipers, R1 Concepts Rotors, Akebono Euro pads. Calipers are <2 years old.
SL600 Rear Calipers, R1 Concepts Rotors, Akebono Euro pads. Caliper are new.
WRXtra Stainless Steel Brake Lines

I've bled the brakes multiple times with the PowerBleeder at 30 psi. No difference really.
I've swapped out the ABS pump/pressure regulator and re-bled. No difference.

I'm not sure where to go next on this. I've half a mind to just gravity bleed the system. I dont think its a component problem but thats only because swapping/replacing made no significant differences.

I'm open to your thoughts. I'm getting rather tired of my all-stock 300D outbraking my 190E with its massive calipers/rotors.

Thanks!

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(4/11/2020: Hi Everyone! I am still taking orders and replying to emails/PMs/etc, I appreciate your patience in these crazy times. Stay safe and healthy!)


82 300SD 145k
89 420SEL 210k
89 560SEL 118k
90 300SE 262k RIP 5/25/2010
90 560SEL 154k
91 300D 2.5 Turbo. 241k
93 190E 3.0 235k
93 300E 195k
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  #2  
Old 10-22-2012, 11:26 AM
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Could it be the master cyl. being too small to deal with the large upgraded calipers you have?. May need to look for a MC with a larger internal diameter bore.
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  #3  
Old 10-22-2012, 11:37 AM
JamesDean's Avatar
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Been there done that too. I had a 500E master cylinder on previously and the effect was the same.

I emailed the shop that originally did the brake work on the car and does brake work on 190E race cars that they built so I switched back to my original master (but new) and booster.

RC Imports

They said they use the stock master/booster setup.

It could be some air in the system still. I've bought a reverse bleeder kit by Phoenix Systems to see if that would do anything. Looks like a nifty device and cool concept.
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82 300SD 145k
89 420SEL 210k
89 560SEL 118k
90 300SE 262k RIP 5/25/2010
90 560SEL 154k
91 300D 2.5 Turbo. 241k
93 190E 3.0 235k
93 300E 195k
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  #4  
Old 10-22-2012, 12:23 PM
whunter's Avatar
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Hmm

Quote:
Originally Posted by JamesDean View Post
Hey everyone,

I thought I had a thread on this topic but evidently not.

I've been trying to chase down my brake pedal feeling crappy for a while now. Compared to my 300D (all stock, with stainless steel lines) the 190E's brake are utter crap, in terms of pedal firmness. With about 1/4 or less of pedal travel on the 300D, I am met with a nice firm feeling. On the 190E I don't get this firmness.

Brake Setup:

190E Master/Booster. Master is new.
E420 Front Calipers, R1 Concepts Rotors, Akebono Euro pads. Calipers are <2 years old.
SL600 Rear Calipers, R1 Concepts Rotors, Akebono Euro pads. Caliper are new.
WRXtra Stainless Steel Brake Lines

I've bled the brakes multiple times with the Power Bleeder at 30 psi. No difference really.
I've swapped out the ABS pump/pressure regulator and re-bled. No difference.

I'm not sure where to go next on this. I've half a mind to just gravity bleed the system. I don't think its a component problem but thats only because swapping/replacing made no significant differences.

I'm open to your thoughts. I'm getting rather tired of my all-stock 300D out braking my 190E with its massive calipers/rotors.

Thanks!
A few thoughts:

* Vacuum supply issue ?
* Damaged/defective WRXtra Brake hoses ?
* Bad new master or booster ?
* The system now exceeds the master design capacity ??


.
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  #5  
Old 10-22-2012, 12:34 PM
JamesDean's Avatar
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Quote:
Originally Posted by whunter View Post
A few thoughts:

* Vacuum supply issue ?
* Damaged/defective WRXtra Brake hoses ?
* Bad new master or booster ?
* The system now exceeds the master design capacity ??


.
If there was a vacuum supply issue would that not make the booster less effective? Wouldn't that make the pedal harder?

I dont think they are damaged/defective. Two I installed a few months ago, largely made no difference. The other two I had my shop install (new hardlines were needed).

I am not sure about the master. It is new and was $250 or so.

I know several people over on 190Rev that ran the stock 2.6 master/booster with the bigger calipers. They didn't have this same problem. RC Imports, the shop that, I think, originally did the brake upgrades used the stock master/booster. I emailed them and they said thats what they use on their race car 190E's. The stock master/booster with bigger calipers.

Even though I've bled the lines with the Power Bleeder for some reason I think it might be air still in the system. Assuming that the parts are good (as most are new or sub 2 years).....

After watching some videos and some suggestions on the 190Rev I bought one of these:

Phoenix Systems V-12 DIY Reverse Brake Bleeder Walkthrough - YouTube

It was only $65, so we'll see what that does. I know that if I pump the brakes a few times, I eventually do get some pressure feedback on the pedal. Posts over on a Porsche forum said they had the same thing, and then they used that bleeder tool and it was fixed.
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Check here for compatibility, diagnostics, and availability!

(4/11/2020: Hi Everyone! I am still taking orders and replying to emails/PMs/etc, I appreciate your patience in these crazy times. Stay safe and healthy!)


82 300SD 145k
89 420SEL 210k
89 560SEL 118k
90 300SE 262k RIP 5/25/2010
90 560SEL 154k
91 300D 2.5 Turbo. 241k
93 190E 3.0 235k
93 300E 195k
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  #6  
Old 10-22-2012, 01:46 PM
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Location: Port Elizabeth, NJ
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I vote for air in the lines.

When recently flushing the (totally stock) brake system in my '84 190E rally car using gravity bleeding, I didn't initially see that there was a divider in the master-cylinder reservoir that was preventing fluid from getting to the rear section and didn't realize I was allowing it to run dry. I'm not sure what kind of bleeder you've been using, but this might be a possibility.

By the way, RC Imports did the suspension and differential mods to this car and they REALLY know what they're doing - I highly recommend them.

Best Regards,
Rob
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  #7  
Old 10-22-2012, 01:57 PM
JamesDean's Avatar
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Quote:
Originally Posted by RobertFini View Post
I vote for air in the lines.

When recently flushing the (totally stock) brake system in my '84 190E rally car using gravity bleeding, I didn't initially see that there was a divider in the master-cylinder reservoir that was preventing fluid from getting to the rear section and didn't realize I was allowing it to run dry. I'm not sure what kind of bleeder you've been using, but this might be a possibility.

By the way, RC Imports did the suspension and differential mods to this car and they REALLY know what they're doing - I highly recommend them.

Best Regards,
Rob
I was using a Motive Power Bleeder, it was full up. We'll see how my new reverse bleeder gizmo works.

RC Imports did a lot of mods to my car. Long before I bought it but they did them none the less. If I wasnt so far I would drive down and have them look see at these brakes!
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Cruise Control not working? Send me PM or email (jamesdean59@gmail.com). I might be able to help out.
Check here for compatibility, diagnostics, and availability!

(4/11/2020: Hi Everyone! I am still taking orders and replying to emails/PMs/etc, I appreciate your patience in these crazy times. Stay safe and healthy!)


82 300SD 145k
89 420SEL 210k
89 560SEL 118k
90 300SE 262k RIP 5/25/2010
90 560SEL 154k
91 300D 2.5 Turbo. 241k
93 190E 3.0 235k
93 300E 195k
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  #8  
Old 10-22-2012, 08:10 PM
compress ignite's Avatar
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ErrrrrrGGGK!

Jim,

"Reverse Bleeding" AKA "Pushing ALL and Any of the accumulated CRAP in the
Calipers BACK UP THROUGH THE SYSTEM AND INTO THE M.C."

Ain't gonna solve Nuffin.

___________________________________________________________________
1.Get a Couple of Great Big 1Qt. containers of B.F. of choice.
2.Fill the Pressure Bleeder with as much fresh clean fluid as it'll hold.
3.Make sure the M.C. is full of clean, fresh fluid( "Back and Front" sections).
4.Pressure Bleed as if your life depends on it.
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  #9  
Old 10-22-2012, 09:19 PM
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Have you tried changing the pads to stock compound and see the difference?

What's the condition of the brake booster hose from manifold to booster? Checkvalve still good?
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  #10  
Old 10-22-2012, 10:43 PM
JamesDean's Avatar
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Quote:
Originally Posted by MBeige View Post
Have you tried changing the pads to stock compound and see the difference?

What's the condition of the brake booster hose from manifold to booster? Checkvalve still good?
I was considering doing that. I've got a set of slightly used Textars here. I was a bit learly of using them again but I figure if I sand them down nicely they shouldnt have too much of a problem.

The brake booster hose seems intact.. I would have though any less vacuum to the booster and my brakes would be firm, hard and somewhat ineffective.

I think I'll give the reverse bleeding a try. All my calipers, most of my lines and the master are rather new so there shouldn't be too much crap in there. All the reviews I saw on other forums had high praise for the device/method. So we'll see. Conceptually, it make sense, to me at least.
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Cruise Control not working? Send me PM or email (jamesdean59@gmail.com). I might be able to help out.
Check here for compatibility, diagnostics, and availability!

(4/11/2020: Hi Everyone! I am still taking orders and replying to emails/PMs/etc, I appreciate your patience in these crazy times. Stay safe and healthy!)


82 300SD 145k
89 420SEL 210k
89 560SEL 118k
90 300SE 262k RIP 5/25/2010
90 560SEL 154k
91 300D 2.5 Turbo. 241k
93 190E 3.0 235k
93 300E 195k
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  #11  
Old 10-23-2012, 01:42 AM
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Posts: 1,332
Another vote for the brake hoses. They can affect pedal feel....
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  #12  
Old 10-23-2012, 08:46 AM
JamesDean's Avatar
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Join Date: Apr 2005
Location: NE Ohio
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Quote:
Originally Posted by JohnM. View Post
Another vote for the brake hoses. They can affect pedal feel....
They are rather new.

I originally had stainless steel lines on the car then I thought the same thing, maybe the lines have failed somehow and I should replace them. Two of them I installed, and two the shop. There was a good 2 month period between the installation. There was no significantly notable change unfortunately.

Its somewhat difficult to describe the entire problem. The brake DO respond and stop the car. It just seems like

a) there is too much pedal travel to achieve this
b) there is no resistance in the pedal (as compared to my other cars)


So what I am going to do is :
1) Reverse bleed.
2) install used textar pads (lots of life, just need smoothly sanded) if #1 should net nothing as compress ignite believes.

What I wont do:
Throw parts at it by buying another master cylinder or by buying more calipers or brake lines.

So we shall see how 1 and 2 do.

The 300D is nearing completion finally. So the 190E's road days the numbered. It will soon go down for the winter.
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Cruise Control not working? Send me PM or email (jamesdean59@gmail.com). I might be able to help out.
Check here for compatibility, diagnostics, and availability!

(4/11/2020: Hi Everyone! I am still taking orders and replying to emails/PMs/etc, I appreciate your patience in these crazy times. Stay safe and healthy!)


82 300SD 145k
89 420SEL 210k
89 560SEL 118k
90 300SE 262k RIP 5/25/2010
90 560SEL 154k
91 300D 2.5 Turbo. 241k
93 190E 3.0 235k
93 300E 195k
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  #13  
Old 10-30-2012, 08:06 AM
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Update!

OK So my reverse bleeder kit arrived yesterday and I was excited to give it a try, even though it was raining like hell. I pulled in the garage and gave it a go.

I read the instruction and they said that it might take multiple methods of bleeding to get all the air out. In the past I've used the pressure bleeder and my shop recently did the 2-man pump method.

I started at the rear passenger wheel and injected 12 squeezes worth of fluid into the system. Then went around the normal pattern of bleeding, using 6-7 pumps each as the instruction indicated. I sucked out fluid as the reservoir filled up. The fluid that came back in the reservoir, was (no surprise) still very clean. I could still clearly see the bottom of my reservoir.

After that bleed, I gave it a quick drive. No really notable improvement. I could still feel air in the pedal. I cannot completely fault the tool as I was hurried to perform the work and probably didn't follow the instructions to a T. It was raining, I was tired and just wanted to get it done with.

So after I got some dinner my friend and I tried the 2-man bleeding on just the front brakes. After that I got a noticeable improvement in pedal pressure. I didn't have enough time to do the rear, but the difference of the combined reverse pressure bleed and 2-man bleed was good enough for the time being.

So, in summary, I think that the instructions were right, to get all the air out you need to do multiple bleeding techniques. I've been doing solely pressure bleeding for years on the car and it really didnt make a huge impact. So if I was someone struggling with this similar problem I would do the reverse-bleed and then the two man style bleed.

I'll post another update later in the week after the weather calms down and I can do a full 2-man style bleed.

I know some people on here will say: bah, the that contraption didn't do anything, it was the 2 man style that did it. However prior to using the reverse-bleed tool my shop did do the 2 man style bleed and it was not nearly as effective.
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Cruise Control not working? Send me PM or email (jamesdean59@gmail.com). I might be able to help out.
Check here for compatibility, diagnostics, and availability!

(4/11/2020: Hi Everyone! I am still taking orders and replying to emails/PMs/etc, I appreciate your patience in these crazy times. Stay safe and healthy!)


82 300SD 145k
89 420SEL 210k
89 560SEL 118k
90 300SE 262k RIP 5/25/2010
90 560SEL 154k
91 300D 2.5 Turbo. 241k
93 190E 3.0 235k
93 300E 195k
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  #14  
Old 10-30-2012, 01:19 PM
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James, I feel the 2-man method is likely to damage the master cylinder. Then you have another problem to deal with. Proper use of a pressure bleeder should work fine since it prevents air from getting into the brake lines. Of course, it's essential that the rear section of the master cylinder reservoir always remains full of brake fluid.
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  #15  
Old 10-30-2012, 01:23 PM
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Quote:
Originally Posted by Ferdman View Post
James, I feel the 2-man method is likely to damage the master cylinder. Then you have another problem to deal with. Proper use of a pressure bleeder should work fine since it prevents air from getting into the brake lines. Of course, it's essential that the rear section of the master cylinder reservoir always remains full of brake fluid.
Can you elaborate on this likely damage? I did make sure my buddy had a foot behind the pedal so that it did not fully go to the floor.

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Cruise Control not working? Send me PM or email (jamesdean59@gmail.com). I might be able to help out.
Check here for compatibility, diagnostics, and availability!

(4/11/2020: Hi Everyone! I am still taking orders and replying to emails/PMs/etc, I appreciate your patience in these crazy times. Stay safe and healthy!)


82 300SD 145k
89 420SEL 210k
89 560SEL 118k
90 300SE 262k RIP 5/25/2010
90 560SEL 154k
91 300D 2.5 Turbo. 241k
93 190E 3.0 235k
93 300E 195k
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