Brake experts ~ please expose yourself!

RINGER

RINGER

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Vehicle pulls left especially in wet weather or on painted surfaces, like pedestrian crossings, for example.
Brakes are all new with 3-400km actual run in time, so should be bedded in.
New IVECO 25mm dual master cylinder
Complete brake system from Holden AH Astra
NEW:
Cupronickel lines & all new flex lines except 2 front which are being fitted today.
Front Saturn Astra Calipers imported from US & same as Holden Astra [bought very inexpensively as wholesaler runout]
Front rotors & pads + rear rotors & pads ~ same reputable brand I always use
Front VH40 450psi in 1470psi out or 3.27 boost ratio
Rear VH44 450psi in 820psi out or 1.8 boost ratio

To pinpoint what was going on I had the vehicle roller brake tested yesterday & these are the results ~

Ideas & suggestions please gentlemen, as these brakes should be near PERFECT ~ but we are not quite there yet!
 

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Brake lines are straight front & rear not crossed as one might think from the report

Front VH40 450psi in 1470psi out or 3.27 boost ratio ~ fitted up front
Rear VH44 450psi in 820psi out or 1.8 boost ratio ~ fitted in boot

To pinpoint what was going on I had the vehicle roller brake tested yesterday & these are the results :~

Ideas & your suggestions appreciated gentlemen, as these brakes should be near PERFECT ~ but we are not quite there yet!
 

Attachments

  • Roller brake test results.pdf
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What about your tyres and pressure, and wheel alignment/camber?
 
New tyres all round, toe alignment done [only adjustment], tyre pressures @ the weekend & I should have been mentioned these things,
thanks JG
 
I'm the opposite of a brake expert .... but how old are the rubber brake lines? The mongrel things have a habit of letting a small amount of pressure through ...... then not releasing it!
 
im no brake expert, but some thoughts . i notice the brake force is higher on the right, could this be causing the right side to lock up ,resulting in the left having better retardation and pulling that way ,the question is why the braking force is higher that side ,on both front and rear ,i presume there would have only been a person in the drivers side when the test was done ,cant see that making a lot of difference ,any degree of engine braking when on the road would be balanced by the differential ! i would have thought
 
Road camber and weight distribution will also cause it to pull to one side. FYI, corner weights on circuit racing cars has more effect on straight line braking than wheel alignment assuming the car chassis is straight.

Also try rotating the pads from one side to the other.
 
driven said:
Apart from old hoses Astra brake systems are supposed to be pressure bled
Read same issue
www.vauxhallownersnetwork.co.uk

[Astra Mk5/H] [04-09] - Astra brake bleeding

www.vauxhallownersnetwork.co.uk www.vauxhallownersnetwork.co.uk
Click to expand...
This is a straight system with no ABS so that won't be the issue, but thanks for the input
Bustamif said:
Road camber and weight distribution will also cause it to pull to one side. FYI, corner weights on circuit racing cars has more effect on straight line braking than wheel alignment assuming the car chassis is straight.

Also try rotating the pads from one side to the other.
Click to expand...
Done did that last week, thanks
DoubleChevron said:
I'm the opposite of a brake expert .... but how old are the rubber brake lines? The mongrel things have a habit of letting a small amount of pressure through ...... then not releasing it!
Click to expand...
Not that issue equal heat on both front wheels @ touch. As stated new on rear & fronts being replaced today & I don't think it will make a bit of difference. Thanks for the input.
COL said:
Not only wheel alignment, but also can be a worn bush somewhere.

Does the vehicle only pull in one direction or does it vary?
Click to expand...
Always the same direction, seems to pull up much straighter when in gear & on dry roads
 
I'm thinking you have only left brake pad type material (assuming no brake pad contamination).
 
All new out of the same box - I'm a tradesman with 60 years experience & really looking for something outside the box.
"NEW:
Cupronickel lines & all new flex lines except 2 front which are being fitted today.
Front Saturn Astra Calipers imported from US & same as Holden Astra [bought very inexpensively as wholesaler runout]
Front rotors & pads + rear rotors & pads ~ same reputable brand I always use"

I am experienced with brakes & roller brake testers having introduced them the US for initial testing of on highway trucks & semi trailers in the 1990's in Ohio & West Virginia.
 
What vehicle? Is this the Traction with the R16 engine? Have you measured the weight each wheel is supporting and adjusted the torsion bars as suggested by the technique in the repair manual?
 
DoubleChevron said:
I'm the opposite of a brake expert .... but how old are the rubber brake lines? The mongrel things have a habit of letting a small amount of pressure through ...... then not releasing it!
Click to expand...
My wife's Mini recently started pulling left. Collapsed flexible hose, looked perfect on the outside.🤷‍♂️
 
David S said:
What vehicle? Is this the Traction with the R16 engine? Have you measured the weight each wheel is supporting and adjusted the torsion bars as suggested by the technique in the repair manual?
Click to expand...
That's the out of the box type of thing we are looking for & the roller brake tester identified weights of 0.3 tonne left front & 0.25 tonne right front
+ 0.20 tonne left rear & 0.35 tonne right rear.
Adjusted all 4 torsion bars so the car was level. Is this not enough?
The car rides wonderfully well & sat in 110km/hr traffic on the motorway for about 100km return trip last Sunday & is still level all round.
 
UPDATE:
2 NEW flex lines on front so now all flex lines are NEW & full system bleed front & back circuits.
Still locks up on a wet road & pulls to the left.
Dropped TP to 195kPa absolutely no difference.

There is a lot more weight on the LH front, as when jacking even offset to the left just near the bottom wishbone, on the crossmember, the RH front wheel always lifts off way before the LH wheel does.

Any new ideas or blood?
 
I don't know what the numbers should be off-hand, but it seems (and I know it's exaggerating) you may have a two wheeler (LHF+RHR) with balance from one of the other two corners. Or possibly a three-wheeler with the LHR doing less. RHR seems to have the most weight of all.
Why is there extra weight at the LHF? Is it due to the torsion bar adjustment or the result of your modifications?
Have a look at the Lt15 manual and see what the standard setup should be and also the tolerance between each corner.
Manuals are at this link, if you've not previously obtained the pdf: Citroën publications list
 
Have you given a full bedding-in treatment to the new discs and pads?
I thought I had but I kept getting snatching and pulling that made braking a bit unpredictable.

I found the 300-400km which had involved reasonably heavy braking was not enough.
After following some suggested methods of FULLY bedding discs and pads they improved tremendously.
Maybe yours need more to get a more even response.

These two links have "reasons for" and "how to" complete a thorough procedure.

Bedding-in and Material Transfer Process | Apec Automotive

apecautomotive.co.uk apecautomotive.co.uk

 
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