steering rack rebuilt but 246 still pulls to left under braking

Well, I removed the steering rack from my 246 and had it rebuilt, then remounted it using nylon instead of the silentblock bushings. Play is gone, I do not feel any unwanted amount of vibration or feedback thru the wheel.

But the symptom that led me to blame the rack and it's worn passenger-side carrier bushing was that the car jerks to the left when the brakes are applied suddenly and hard. It tracks straight and true under neutral throttle and acceleration.

The drivers side front wheel has no play in vertical or horizontal plane, the passenger side has just the slightest perceptible in the vertical plane only-- essentially none in the horizontal, whereas before it had huge play as the tie rod moved up and down in the rack carrier bushing. I looked at the passenger side wheel bearing and no rust, etc.

All the wheels turn freely-- no symptoms of a frozen or binding caliper.

What's next?

 

Ball joints?

 

I doubt ball joints.

It would knock if a ball joint was worn out, not so much pull to the left or right under braking.

Interesting issue. Was is pulling to the left under braking BEFORE you rebuilt the steering rack?

 

How about an A-arm bushing deflecting under braking (or a broken/cracked A-arm )...

 

Yes, it was. I thought it was the worn rack bushing that was causing the pulling under braking, but I can't say it's any better now. :-(

 

Could be the bushings-- I replaced the rears a while ago but not the fronts.
But shouldn't I be able to move the wheel / suspension assembly around if they were that worn?

I'll look at them carefully this weekend

Jim

 

Although the wheels spin freely,Im tipping that there is a problem with your front right caliper.

 

If a "floating" caliper isn't floating, it might not show as a binding wheel.

You could have a case where the caliper isn't sliding, so only the piston side pads are pushed against the rotor.
Look for uneven pad wear (inner/outer).
Or have someone apply the brakes and probe between the pad and rotor with a leaf type feeler gauge.
Or use a pyrometer to compare inner and outer rotor surface temps after hard braking.

I had a case of "pulls left under hard braking" on my 328, and it wound up being oxidized caliper slides keeping the caliper from floating freely. On a hard stop, the left front would lock up.
The calipers were removed and cleaned -- problem solved. The shop didn't have to break open the hydraulics.

 

Ok, but it still sounds like you needed to rebuild the rack anyways.

So nothing lost there.

I would inspect the brake caliper/brake pads very closely mate.

Also, inspect all the suspension components and bushes at the LF wheel. I also also leaning towards a brake caliper issue.

Yep, unless there is something DRASITCALLY wrong with his suspension.

 

Suspension issues should show at times other than when braking.
Such as the wheel pulling to the side when hitting a seam in the road (bump steer), or a propensity to power oversteer, or excess understeer.

I had a bent *rear* trailing arm (from being tagged in the right rear wheel by a cell phone zombie) on the EVO that caused a steering inbalance, but not just under braking.

The Celica had a case of pulling to the right on bumps when the front springs were bad (impact damage after a rim broke).


Check the calipers thoroughly.

Check your bumper height. (Should be consistent left to right.)
(I think the 246 pre-dated the US 18 inch bumper height standard.)

And if it hasn't had a four wheel alignment recently, you should look into getting that done.
(A basic alignment can be DIY, but the "full monty" is best done with a Hunter machine by a specialist on the Ferrari, who will have the shims on hand.)

 

Does it pull if the brakes are applied lightly?

How old are your brake lines?
I'd be looking at the right front brake line for an internal obstruction.

 

Right side brake hose is obstructed.

Probably time to replace all brake hoses.

 

A 246 doesn't have "floating" calipers.

 

Not necessarily -- you can't apply the high forces like sudden braking (and it's not like it would be "loose", just something might be doing some unwanted flexing). The guys bring up a good point about brakes, but, if you can't find the fault there, you'll have to look deeper.

 

you ALWAYS start with the brakes-be it girling, dunlop, or teves calipers...and no, camry type "full floaters" were NEVER used by Ferrari in this era.
Period...

I can't even fathom the thought process: step on the brake pedal, the car pulls right(or left as the case may be..),
so I rebuild the steering rack?
Why?
You stepped on the BRAKE PEDAL-shouldn't one start with looking at...the brakes?

Old saying in the military: KISS-keep it simple-stupid....

You ALWAYS, ALWAYS, ALWAYS start with the rubber brake lines-if original-they are 40 YEARS OLD!!!! Think of hydraulic pressure...

Then, if problem still exists, you start to examine calipers and then work your way-functionality wise-back to the pedal.

Suspension bushings are the LAST thing-along with shocks and springs-that one examines...as if there were truly a fault there, the resultant symptoms would have such a dramatic effect that: you would NEVER even have to examine the brakes..,.
there is NOTHING subtle about suspensiopn pivot failures....in these cars

 

Check the brake lines. They can look perfectly fine on the outside, but collapse internally while braking. I had this happen on my 308 under exciting circumstances! It's usually the last thing you look at.

 

The steering rack bush was worn and needed to be replaced anyways.

Not a problem, needed to be done.

Obviously Jim is not an expert, which is why he is asking for help here.

 

I understand your thinking and that's what I used when my Pantera (which uses exactly the same rack) was showing exactly the same symptoms some years ago. I replaced both front calipers and lines and it had ZERO effect on the symptom. I took the car to a club diagnostic meet and they found the worn carrier bushing-- replacing it cured the problem

It made sense to me that when I applied the brakes the right front wheel was turning inward, causing the symptom. I'm still amazed fixing the rack hasn't changed anything because I could move the wheel back and forth at least 5mm with the car raised.

I think you're all right-- a plugged brake line on the right would do this and that is most likely the problem. No, the pulling is not noticeable with gentle brake application, so the fluid / pressure must be getting thru if the pressure change is gradual.

Where is the best place to get new lines? Teflon-lined SS braided seem to be the rage now-- are they what I should get?

Thank you,

Jim

 

I dont want to sound like ******, but do you think you should diagnose some more and find out the issue before you just throw money at a set of SS brake hoses?

If you dont want to diagnose the problem, here is a link for some SS brake hoses in the UK.

http://cgi.ebay.com.au/Goodridge-Stainless-Brake-Hoses-Ferrari-246-Dino-/300538678514?pt=UK_CarsParts_Vehicles_CarParts_SM&hash=item45f9804cf2

 

Jim,
It doesn't have to be a plugged line. A kink or a fold in one line will act like a pressure attenuator on that side and allow the off side to lock up. Check both sides!! The kink itself doesn't restrict flow but when you step on the pedal the kink has to expand back to its original dimension and thus cause a pressure imbalance.

Rick

 

Considering that I have owned the car since 1987 and know those hoses have not been changed since, I look at it as "maintenance I should have done anyway and will probably solve the problem". Similar to the rack rebuild, really--it needed to be done so it's not like I threw money away. (To say nothing of the improved feel I should have because I went to nylon rack bushings)

 

One thing I will do before I pull those hoses off will be to have someone press lightly on the brake pedal while I try to turn each front wheel to see if they are equal. It is remotely possible that one piston has seized in the "off" position.

But since I change the fluid annually I think that's unlikely

 

No need to waste money on the fancy SS braided lines if you're street driving. The old ones lasted 30 years.

The hoses aren't particularly unique. If there's a shop in town that specializes in rebuilding brakes and clutches you might be able to have them made up for you (bring in the old ones). I have a shop near here (DOT licensed) that does it while I wait.

 

Couldn't you just open the bleeder on that side and have someone pump the brakes? A blocked or collapsed line wouldn't bleed well, would it? then decide if the lines need replacing.

My Dino had, as far as we could tell, the original brake lines on it when I bought it. We examined them, checked the brakes, and left them alone.

Seems like a pretty simple test that might tell you if the line is the problem, especially since it would be easy to compare to the other side for flow.

Just thinking out loud. I'm not really a shade tree mechanic, more of a shade tree kibitzer.

DM

 

Sometimes you can tell a difference but not always. Sometimes the flow is blocked going toward the caliper (cutting off braking to that side), sometimes the blockage holds the pressure after releasing the pedal (causing the brake to overheat and lock up). Any time I experience uneven braking that isn't obviously something else it's usually the hoses.