Technical UPDATE - Pulling to the right when braking

Johnny's info is spot on. Tire issues are age old and well known. Generally a strange ware pattern shows as well as a balance issue if it's them.

 

Tire conicity will pull driving not just under braking


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The normal vs hard braking makes me think stuck caliper on the opposite side. Try using a bar to pull the outside pad back. Just remember to pump the brakes before driving. You said disc brakes stock suspension or something like mustang II ? If you have strut rods pay close attention to the bushings they can cause problems when braking.

 

I agree tire problems will be there all the time, you will definitely feel it just driving

 

I don't suppose you have a local garage with a brake testing machine (like a rolling road)? Certainly helps identify exactly which wheel is the culprit, but doesn't diagnose the problem!

Mandatory annual inspections are required on all vehicles in the UK covering all safety aspects. Applies to all vehicles over 3 years old. Somewhat counter-intuitively cars of more than 30 years old have been comparatively recently exempted from that test, or it becomes optional. I've opted out! But the thorough test does help find things that are problems waiting to bite you in the ass. I've had early detection of failing wheelbearings, worn kingpins, deteriorating brake flexibles. I might opt back in!! $60 - $70 well spent?

Chris

 

If it were just brakes involved, meaning there’s a pulling issue under all braking conditions then your problem is on the opposite side of the pull.

However if the problem is only under hard braking when there is considerable weight transfer and front dive you’ll be inspecting the suspension,,,squishier bushings, geometry, sticky articulations, spring rates, rear suspension travel.

Road test with open mind and knowledge of results and reactions is the only way to tell.
Hope you find it easy

 

Yup, my $$ is on a bad LF brake hose, replace both.

 

Wouldn't a restriction in a hose react to pressure the same all the time be it easy braking or hard braking?

 

Yeah.

Yes sir.

When the front suspension was lowered new coil springs and shocks were installed, and yes sir the car has been aligned.

True, while you can't see if there is a internal hose problem, like collapsing and not allowing the fluid to travel back and holding pressure, much like the caliper being stuck so the only thing to do is replace both the front brake line hoses.

I replaced them.

The tires are new and have been speed balanced.

There again, the tires are new with a little over 600 miles.

My thoughts also.

I tried that yesterday.

Yes sir.

We don't have a shop like that in my area but the front suspension has been rebuilt.

Who knows, I'm still trying to figure out what the problem is however I have address several ofr your suggestions.

That is my next step, however I will replace both the front hoses.

Thank's again for all the suggestions, you guys have already helped me eliminate several things that may have caused the problem. HRP

 

Danny,
Just a " kitchen sink" suggestion...
Could it be the crown or slope of the road?
You may want to test it on a flat parking lot.

 

My 72 Monte Carlo pulled real hard to the left going down my parents driveway one night. I looked out the window down the front fender and there was that rally top hat looking back at me.
The lower assembly had broken off the frame turning the whole wheel assembly out.
I had a hard time finding a shop to fix it. That was nearly 30 years ago now. Man time flies.

I would check that suspension assembly real real close. Something may be trying to turn loose.

Does this car still have the king pin IFS?
You may want to get those front wheels up and check for looseness in the pins or ball joints.
I would try the side to side wobble test too. I know it's been aligned but these days......well, you know.

 

While I tend to agree with the delaminated hose theory, did you check the rear suspension? A bad front bushing or broken center bolt on the leaf spring could cause a brake pull. Especially the left side in your case. Generally, but not always, worn suspension components will cause a pull, while under acceleration, in the opposite direction of the brake pull.
I've experienced cars with bad hoses that pulled momentarily and then straightened out. It takes not only pressure but volume to make brakes work properly. The car pulled, then straightened out because the restricted line slowed the required volume to move the piston on that side. It sounds like you have a case of under light or normal braking the restriction doesn't cause a noticeable problem, but under hard braking enough pressure gets behind the delamination to cause it to shut off the fluid flow. If your hoses have a metal bracket around them in the middle of their length that would be a good place to look for the bad spot.

 

Back to conicity. I left out the while driving for a reason. My 56 suffers form bad scubbing due to type of rotor I'm using compounded by wheel off set. On top of that (until I replace upper shafts with offset ones) I can not get the proper camber adjustment. So after time I get coned shape tires (inside) then it pulls while braking hard. Flip the tire or by new ones good to go again.

All that wording just to say. Is camber off on one side?

 

Different rate of fluid flow, so maybe not.



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I was trying to think the same way but then seems the P.S.I. is the same no matter the volume and the P.S.I. is what makes brakes do what they do no matter how they are applied. I'm just trying to get my head around the bad hose theory. Would seem if you had any kind of inner separation of the hose it would only be a few times on the brakes and you'd then have a total failure of that hose.

 

It's always said change parts in sets. Any possibility the calipers are not equal?

 

You need a certain volume of fluid to move the caliper piston a certain distance. If there is a restriction in the hose then that piston is not going to get enough volume of fluid to move the pad into solid contact with the rotor. Hoses have built in safety margin. Hopefully you recognize you have a problem before you exceed that margin. For example you have seen radiator hoses that delaminate and balloon but not burst. Keep going and eventually they do burst.

 

I’ve said it before, less than a teaspoon of fluid actually flows during a brake application, it is pressure that does the trick, not “flow”


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Flow matters to the extent that a restricted front brake hose could possibly make that side lag behind the other side a split second... causing the momentary pull only under hard braking.

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... as in sudden hard braking.

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But I'm also concerned about all your steering links etc, Danny.

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... bearings and stuff, even.

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I had a '82 Chevy wagon, that one had a sticky caliper on the side. I could see the smoke come off the cooking brake pads, the hubcap itself was hot. Just drive it a bit, make some medium to hard stops. If there is a side to side heat difference it points to a sticky caliper.

 

If it is blocked then yes it could, restricted I don’t think so. It would have to be virtually plugged to do so. My vote is on a caliper issue of some sort.


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Take a mouthful of water and blow it through a regular soda straw. Now repeat with one of those little red straws from a WD40 can. Now repeat the experiment, but blow harder.

To have pressure at the piston, you also have to have flow. Not a lot, but a difference in flow, side to side, could produce a pull, especially under hard braking, with one side (soda straw) grabbing before the other (WD40).



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Long shot, but in inspecting the pads, did you check for de-lamination? I've seen the friction material separate from the steel and sort of wedge in place under hard braking. More common on bonded drum sets, but an happen to any of them.

 

Bore/Piston diameter is what I'm referring to.

 

I am not buying the hose theory in this case for the following reasons.

A restricted flow should affect the brake more on light brake application, allowing one brake to apply easier/faster than the other. On heavy application the restriction would be less effective due to higher line pressure from the master cylinder. Frankly, I don’t think this is likely.

Secondly, my prior actual experience with brake hose interior deterioration had no effect on brake application because the M/C pressure easily overcame the restriction. What was apparent is the brake with the defective hose would not retract because neither the brake shoe springs (in one case) nor the caliper piston O ring (in the other case) could exert enough force to push the fluid back to the M/C. There is no mistaking the remaining near lock up of the brake after releasing the brake pedal. That can also result from blockage of the return port in the M/C. But in either situation it doesn’t go away without correction. In HRP’s case, no mention is made of subsequent brake ‘dragging’.

Certainly no harm will be done (except possibly to your $$) by replacing the hoses. The real problem with successful trouble shooting is the too often tendency to change more than one thing at a time and not evaluating the results of each individual change. When the problem is ‘fixed’ we often don’t know for sure which change corrected it.

 

The bearings are new. brake pads are new, calipers are also new, wheels are new, tires are new and have been balanced, suspension has been rebuilt and aligned and I had absolutely no problems with the brakes since I got the car up and running a few months ago, until Sunday morning.

I have ordered new hoses for the front because I wouldn't think about replacing just one, will it cure the problem? I don't know but I won't have to worry about it, hopefully I will get this done over the long weekend. HRP

 

My issue with this theory is under a hard brake application there will be a sudden burst of pressure which should be less affected by a restriction then during a light brake application. Remember once the system is full the fluid acts as a solid. The issue with your comparison is the fluid has somewhere to go (out the end of the straw). In the brake system there is really no where for it to flow to once the pad touches the rotor, which is virtually instantly, or at least should be.