I recently ran into something I've never seen before in all my years of wrenching on cars: swollen brake caliper pin boots and seals.
I had an issue on my Kia Forte GT where the grease that they used at the factory hardened over time, and that froze the calipers. Once I cleared everything out of the slide bores, I went to the parts store and bought a can of this stuff:
It says right on the bottle you could use it as a caliper pin lube, so I used it.
When I had the same issues with locking calipers yet again on the car (seriously, it's getting old now), I took everything apart and was greeted with a swollen boot and a swollen pin seal.
This was causing the brakes on my Kia Forte GT to lock up, as air was getting into the caliper pin bores and locking them up once I hit the brakes on one slide, and the pin with the rubber seal on the pin was not moving at all. But why did this happen?
After doing some research I learned that my problem may have been self-inflicted. Apparently, this type of grease is a no-no for anything that has a rubber seal. I never knew!
I've since ordered a can of Syl-Glide (which apparently does NOT do this) and a pile of new seals, but how have I missed this in all my years of working on cars? I've used similar products in the past and never had an issue. Maybe I was just lucky.
What dumb, self-inflicted mistakes have you made to your cars?
To my knowledge I haven't had this issue yet using the same caliper grease in the same applications. I wonder if something is changed in the grease formula or the rubber formula on your Kia. Interested in seeing how this discussion unfolds
Interesting. Last time I did brakes on my "Everlasting Donor Car™" I bought a jar of this exact same stuff thinking "I'm being a responsible adult using the"proper grease" this time instead of my ancient can of red-tack.".
Coincidentally, it also started pulsing and locking up again which is why I did brakes in the first place. So it will be interesting to see what I find when I take it apart.
Dusterbd13 said:To my knowledge I haven't had this issue yet using the same caliper grease in the same applications. I wonder if something is changed in the grease formula or the rubber formula on your Kia. Interested in seeing how this discussion unfolds
Same here. I just did this yesterday, no real issues when I changed pads despite using this same grease in the caliper slides of our Mazda. I'll keep and eye on it and maybe use something different next time
This is one thing I actually knew! I used Syl Glide on the parts that touch rubber. I still managed to F up my brake job by forgetting to torque a bolt all the way, so yeah, nobody's perfect.
So I went and checked the shelf here at work...
The CRC directions say to only apply the product to the pads where they contact the caliper. Does not mention anything about rubber or plastic anywhere.
Both the Permatex brand and the Kleen-flo brands specifically call out being safe with 'all rubber and plastics'
So maybe something in the CRC doesn't play nice with rubber? Also of note, the CRC we have here is a smaller container that looks different from what is posted in the thread so may not be an apples to apples comparison.
I have been using Syl-glide for a few years now, thanks to the GRM forum. Ordered a tube this morning. Works great, and the tiny brakes on my civic get a workout.
It still holds the record for the highest caliper temperature from a single lap at a track sprint at the Firm, 700 degrees.
In reply to DjGreggieP :
The "Disc Brake Quiet" isn't the same product. Here's the back label from the synthetic brake lube:
I mean, it says right here that that it won't mess up rubber AND to use it on caliper slides, bolts and pins. Figured I'd be safe using it. But... nope.
Here's a thread from the Bob Is The Oil Guy forums all about this issue.
In reply to DjGreggieP :
That's a different product. I had some of that on hand from when my Kona N started making fun screeching noises from the brake pads as it was recommended on some of the threads about the problem.
Never applied it though. The noises stopped after my track day at Putnam Park, guess the compound Hyundai used needed some more aggressive bedding than regular pads.
I used the black CRC synthetic lube on my slide pins on the Audi and the Foz when I did the brakes and haven't noticed any issues. I should get some Syl-glide though.
Edit: Just read the link on BITOG. Eeek, the Audi has rubber bushings on the slide pins I think. Guess I better check them while it's down for the oil filter housing replacement...
Is there a chance the boot got exposed to brake fluid without being neutralized? Because I know brake fluid will do that.
I actually had a friend put about 2oz of brake fluid in his power steering to stop a leak in his rack. 100% do not recommend, but it did stop leaking and he probably put another 60k on that car in Los Angeles without an issue. (IIRC he flushed the system a week later.)
In reply to Crackers (Forum Supporter) :
In my case, no. All of the original brake fluid is still in the system with no leaks, and unless there was a fairly major leak, there's no way for fluid to reach a caliper slide boot. Speaking of which, I should probably flush that fluid.
Brake system rubbers are generally safe with brake fluid, but do not like regular petroleum based grease.....just as you can't use mineral based brake fluid in brake systems, unless you drive a Citroen that takes the green fluid!
I always used a silicone based grease on brake slides and other external parts, and red Girling grease on internal brake parts on assembly.
Learned from experience when I fought with our Pathfinder brakes in a campground 1800 miles from home...
Some Japanese car manufacturers use EPDM (ethylene propylene diene rubber) for brake caliper pin boots and seals, which is not compatible with petroleum-based greases. EPDM rubber can degrade when exposed to conventional greases, particularly those with petroleum or mineral oil bases. Instead, manufacturers specify non-petroleum-based greases, such as silicone-based greases or polyglycol-based greases, to avoid damaging the rubber components
Huh. I've always used whatever I had around which typically is just a tube of Super Lube silicone grease. Never had an issue. Lucky I guess! Or I'll use the grease that comes with brake pads, that also works
Hope this fixes your braking issue! I've read through your build thread and the constant braking issues must be frustrating.
In reply to spandak :
Yeah, I really hope this fixes it for good. It has gotten to the point that I want to drive the thing off a cliff! Beyond frustrating.
Quick Update: I pulled everything apart yesterday, cleaned off all the CRC grease, replaced all the rubber boots and pin grommets, slathered everything down (including the pad slides) with Syl-Glide, and put it back together. Result is 4 working calipers. Fantastic.
Turns out, all of the calipers were binding up. Even the ones I serviced just a few days ago.
Moral of the story: Syl-Glide is the stuff. I'm never using anything else on brakes.
You'll need to log in to post.
