Lotus Elan

Troubleshooting Brake Drag / Pull When Braking

PostPost by: 1969Plus2 » Mon May 25, 2020 3:47 pm

My post-hibernation woes continue on as I prepare for this year's driving system.

With the power plant mostly sorted I got out on the road and noticed that the car was pulling to the left (drivers side) while braking. It isn't enough that you'd really notice it if you were holding the wheel straight but when your hands are off the steering wheel at low speed and when you braking hard at speed it is very noticeable. The car drives straight as an arrow when you aren't on the brakes.

After checking the tire pressure, all good, I moved onto the brakes. Jacking the car up I spun the drivers side wheel and it rolled freely, making several rotations after a light spin. Moving onto the right (passenger side) wheel, you could spin it but after a push on the tire it made it about an 1/8th of a turn before it can to a dead halt.

While I would have though that a dragging caliper could cause the car to pull to the side where the drag is, I am wondering if the drag is an indication that the piston in the caliper is stuck somehow and both dragging and also not applying enough force, which would explain the direction the car is pulling. Perhaps corrosion after not being driven for half the year?

Before I start pulling everything apart and figuring out how to troubleshoot with a shotgun approach, I was hoping to get a few ideas on where to logically start and methodically work through the problem, starting with any known issues that might arise.

Help?
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PostPost by: h20hamelan » Mon May 25, 2020 7:07 pm

Brake fluid is hydroscopic
When was the fluid changed last, this year or last year.
Your piston will need some playing with, front right. Rear left, or all.
If you use a block of wood, the piston wont push out fully. Just enough to get movement and new fluid.
Sounds like a hot tank, honing, and rebuilding of callipers is in order.

P/s brake fluid is the best penetrating oil known, but it eats paint...
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PostPost by: 1969Plus2 » Mon May 25, 2020 7:17 pm

I am not totally sure I totally understand the advice. Is it to take the caliper off and push the piston back in, to rebuild the caliper, change the fluid / bleed the breaks or all of the above?

The fluid hasn't been changed / brakes haven't been bled for over a year, probably longer than that.
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PostPost by: HCA » Mon May 25, 2020 7:34 pm

These are your front brakes you are talking about - the things that keep you alive! Sorry but you do not play around with blocks of wood!

Your RH caliper is not doing its job. Pull it off and do the job properly. Do the other one as well. And flush out the old fluid with new.

Your call though!
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PostPost by: 1969Plus2 » Mon May 25, 2020 8:09 pm

HCA, I 100% agree, I want to the job right. I am just trying to understand the root cause as well though so that I can be sure that I am taking all the right steps and also get smarter myself.

Three questions:

First, is the behavior that I am describing (pulling under braking and a dragging caliper) consistent with a stuck caliper piston?

Second, is the recommended course of action to rebuild the brake caliper or is there another first step that would be worth trying.

Third and a half, if a rebuild is required, is this something I can on my own or am I better off buying replacement calipers and / or having someone else rebuild? Where did the plus 2 calipers come from?
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PostPost by: HCA » Mon May 25, 2020 8:17 pm

Yes.

Yes.

If you are confident and compitent, then do it, otherwise get them done professionally.
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PostPost by: nmauduit » Mon May 25, 2020 8:28 pm

I would just drive it a bit (carefully, then braking some) and see if they still drag, most likely it's only a bit of corrosion built up on the rotor hile sitting for 6 months if they were fine before... If the wheel can be rotated by hand it won't make the car drag to one side (yet one would not want a piston corroded into a caliper that would lead it to drag and heat...)

standard disclaimer : what works for me (when I'm lucky) is not a warranty of any sort, expressed or implied, to work again for anyone else or even myself, use of one's betetr judgment is strongly recommended.
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PostPost by: 1969Plus2 » Mon May 25, 2020 8:38 pm

Nmauduit, just to confirm the symptom though, the car drives straight and only pulls when applying the brakes.

My hunch was that whatever is causing the right wheel to drag is also causing the caliper to not apply enough pressure to the right side, which is causing the car to pull left when braking.

Does that make sense?
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PostPost by: h20hamelan » Mon May 25, 2020 9:07 pm

It’s not the wheel that spins freely or not.
It’s the direction of travel the vehicle takes you under braking.

You said it was pulling left.

When a vehicle pulls to the left, chances are. Your front right, or rear left is seized. Or, your opposite brakes (front left and rear right) are working. And a very good thing to do often, is drive fast (down a hill) in reverse. Which will use more rear brake than front.

Using a block of wood, as a rotor/disc spacer. Shows where you get piston movement. If the piston stays put (seized, does not move) then, thats the one requiring freeing. And or new bits/rebuild etc.

I would get 2 Liters of dot 3. Remove the calipers, add the lumber. Depress brake pedal. Go and look to see if there is indeed a frozen/ceized piston. If you cant free up that piston, have it refurbished. Most likely you require a rebuild kit including rubbers, snap-ring and a piston for the offending calliper.

Also, invest in a infrared thermometer, then you can tell which brake takes more heat. $20, doubles as Cv-19 scanner for any unwanted guests/in-laws.
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PostPost by: h20hamelan » Mon May 25, 2020 9:19 pm

Also some parts numbers here.

http://gglotus.org/ggpart/elanxref.htm

NAPA, carquest or whoever you use probably has callipers. RDENT and Bean are the pros.
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PostPost by: HCA » Tue May 26, 2020 9:51 am

1969Plus2 wrote:Nmauduit, just to confirm the symptom though, the car drives straight and only pulls when applying the brakes.

My hunch was that whatever is causing the right wheel to drag is also causing the caliper to not apply enough pressure to the right side, which is causing the car to pull left when braking.

Does that make sense?


How many times do you need to hear the word 'yes' :?: :D Again, your RH caliper is not doing the job at all or not well enough. It is in fact encouraging you to veer headlong into oncoming tarffic on braking :lol: It is your enemy, kill it :twisted:

Seriously, it strikes me that you are not fully au fait with brakes. My advice: Take the car to an expert, ask for all four corners to be examined and repaired, ask for your master cylinder also to be examined and repaired as necessary and flush in new fluid.
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PostPost by: nmauduit » Tue May 26, 2020 9:54 am

1969Plus2 wrote:Nmauduit, just to confirm the symptom though, the car drives straight and only pulls when applying the brakes.

My hunch was that whatever is causing the right wheel to drag is also causing the caliper to not apply enough pressure to the right side, which is causing the car to pull left when braking.

Does that make sense?


I had read the initial post a bit quick, taking the car was on stands and wheels dragging differently from side to side...

if it pulls under braking then brakes require attention : it is likely that either dirt or most likely corrosion is preventing the pistons to apply identical force to the pads on both sides. I would check both calipers of each axle to preserve the symetry, first step being to take out the pistons for a careful examination (they are often the ones that get corroded, esp. if of the chromed steel kind, the corrosion tend to lift the chrome and rust builds up underneath blocking the travel near the resting location at the rubber seal): that will let you assess if a change of pistons is required or if a cleanup will be enough. A new seals kit for reassembly will be required in any case (I prefer to use a tiny bit of brake grease to avoid risking damaging the edge of the new seals, but short of brake grease some clean brake fluid would help). A good purge will let you back on the road, a rather straightforward maintenance job if taken patiently.
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PostPost by: 1969Plus2 » Tue May 26, 2020 12:59 pm

HCA, somehow I missed your last post with the yes yes yes advice.

You are correct in that I have not done an enormous amount of brake work. Just trying to get smart so that I can order the right parts and take my time to do the job right. Many thanks for the help.

This is probably just another reason why you shouldn't let your car sit!
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PostPost by: alan.barker » Tue May 26, 2020 1:14 pm

If you fit new Caliper Pistons fit Stainless Steel.
John Farrell in NY sells Stainless Pistons.
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PostPost by: pharriso » Tue May 26, 2020 2:07 pm

alan.barker wrote:If you fit new Caliper Pistons fit Stainless Steel.
John Farrell in NY sells Stainless Pistons.
Alan


John Farrell is retired & no longer in business.
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