Brake caliper issue

[LTeddy]

 
Not saying you did. Was just saying there's a post similar to this in the Facebook groups once a week at least and there's a group of guys that like to bash me because I say it's a stupid idea.
 
That being said you took off a lot less then most people I've seen. Most of the ones I've seen they grind the whole bump flat. I think you'll be ok it doesn't look like they took to much off. Just paint them so they don't rust. Maybe even ceramic coat them while you're at it...
 
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 Yup definitely getting them painted next week!! The guy who did it said if he had to take anymore off he wouldn’t and I would have to do the rest cause he wasn’t going any lower
 

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[cc1999]

I know this is an older thread, but also a common issue. 

Just received my new Fuel Anza wheels 17x8.5 , with P295/70/17 tires all mounted up ready to go. 

 

Unfortunately that brake caliper casting bulge strikes a again. 

4 websites all said these wheels would fit my 2019+ GMC or Silverado 1500. 

 

I have a very similar problem, looks like I will need to shave my calipers down about the same amount as you did to clearance my new rims. 

Just curious if you have seen any problems arise from it. Honestly I don't think it's all that big a deal.

But there is plenty of people out there somewhat freaked out about it. 

 

Edited December 17, 2020 by cc1999

[cc1999]

Got them clearanced , no problem. Took about 30 min for each front caliber. Took about half that bulge off. 
Rides and drives great. 
I am a happy camper now.
 

[Ronjon]

On 12/17/2020 at 9:32 PM, cc1999 said:

Got them clearanced , no problem. Took about 30 min for each front caliber. Took about half that bulge off. 
Rides and drives great. 
I am a happy camper now.
 

Any problems? Also have we concluded whether or not it's a fluid channel or some stupid design?

[The Juan and only]

I’m about to do the same to my calipers, have you had any issues at all after doing it? 

[jweezy]

So obviously, I'm having the same predicament with my wheels and calipers. I decided to order a used caliper from ebay and I'm going to drill and sand down the hump to see how much metal is there. I've ran a 3/8's hub centric spacer and I'm currently on a 1.25" hub centric spacer. Still, the bigger spacers cause some rubbing and the smaller spacer takes up too much of the wheels stud to where there isn't much threads left. Obviously I'm not happy with the outcome of either spacer but in short I'll post pictures as soon as I get this caliper.

[jweezy]

On 10/22/2019 at 2:20 PM, LTeddy said:

 

So I went this morning to get my rims and tires put on from my previous truck to my new custom trail boss.. fuel maverick 18x9 +14 offset and they did not work spokes were bumping into the little hump on the caliper.. put a 1/4 spacer on no dice.. he ended up grinding that hump pretty far down.. my question is has anyone done this or heard of doing this? Any issues anyone sees of doing this? It’s already done just hoping I didn’t make a bad call

 

 

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So I ordered a caliper off of ebay to further research this whole hump issue we all have with the new calipers. I actually took them apart and there is nothing behind the piston! So I decided to grind the hump and I actually grinded it all the way flat! I'm still going to drill the caliper through the small passage from inside the piston cup to see how thick the sidewall still is.

[asilverblazer]

The rib across the back of the pistons is to reduce flex or deformation of the caliper. It was engineered there for a reason - taking any of it off is risk vs. reward calculation. 

[jweezy]

13 hours ago, asilverblazer said:

The rib across the back of the pistons is to reduce flex or deformation of the caliper. It was engineered there for a reason - taking any of it off is risk vs. reward calculation. 

Maybe, but if that's the case, wouldn't the inside half of the caliper have the same reinforcements? The rear half actually has less metal in the design, you could actually see the outline of the piston cups. I still plan on cutting the front half down the middle to see how thick the metal actually is on the oil passage part of the caliper. I'm no engineer and I don't have access to those documents, so I won't and can't tell you what GM engineers were thinking or why they designed something a certain way. What I will say is that these calipers look pretty similar to older Brembo caliper designs, but I'm also not saying that they are just that. Either way, what I'm trying to do is provide other people here with some actual measurements and answers to the wonders of these calipers. Being that automotive hydraulic brakes only apply around 400 lbs psi during light to medium use, if there is enough metal there, then there should be no worries about having brake fluid burst the side of the caliper. As far as it flexing under pressure, I can't say much about that either. Unless, I fully grind down and install the caliper, apply brake pressure and take measurements of it to see if there was any flex. Now if you are a GM engineer or have access to such documents, then my apologies and please share the info, it would definitely save me the headache and save everyone else on here the time on trying to find the actual answer to this mystery.

[asilverblazer]

7 hours ago, jweezy said:

Maybe, but if that's the case, wouldn't the inside half of the caliper have the same reinforcements?

Not necessarily, the inside of the caliper is loaded differently from the outside. The inside face between the pistons is in tension, which is controlled by the additional metal surrounding the pistons, the outside, where the rib is, is in compression. 

 

7 hours ago, jweezy said:

The rear half actually has less metal in the design

Likely the reason for the rib.

 

7 hours ago, jweezy said:

Either way, what I'm trying to do is provide other people here with some actual measurements and answers to the wonders of these calipers. Being that automotive hydraulic brakes only apply around 400 lbs psi during light to medium use, if there is enough metal there, then there should be no worries about having brake fluid burst the side of the caliper. As far as it flexing under pressure, I can't say much about that either. Unless, I fully grind down and install the caliper, apply brake pressure and take measurements of it to see if there was any flex. Now if you are a GM engineer or have access to such documents, then my apologies and please share the info, it would definitely save me the headache and save everyone else on here the time on trying to find the actual answer to this mystery.

I doubt fluid will burst out of the caliper... Back in the early 2000's GM had Bosch (If memory serves...) assist with the re-design of the brakes on full size trucks. One of the findings was excessive flex of the caliper. The result at that time was poor pedal feel. How much flex was there... don't know.

 

In this case I doubt it would even be measurable. Some material analysis in a computer simulation likely showed it. 

 

In practice, trying to reverse engineer a brake caliper with grinders, tape measure, or any tools any of us have access to won't reveal much. You could grind it off completely and likely never even notice; but there is that one scenario out of ??? that it would be a problem. 

 

Not sure what actual answer to the mystery you would expect to find that you haven't already - grind it off completely. Bolt it on and see what happens is all that's left. Unless we want to wait for the engineer to post his analysis and design of the caliper.

 

Not being a jerk or anything, just having a discussion about it.

 

[davester]

It's one of those things where you only find out if you went too far, in a circumstance where you really really wish you hadn't done the mod.

[jweezy]

2 hours ago, asilverblazer said:

Not necessarily, the inside of the caliper is loaded differently from the outside. The inside face between the pistons is in tension, which is controlled by the additional metal surrounding the pistons, the outside, where the rib is, is in compression. 

 

Likely the reason for the rib.

 

I doubt fluid will burst out of the caliper... Back in the early 2000's GM had Bosch (If memory serves...) assist with the re-design of the brakes on full size trucks. One of the findings was excessive flex of the caliper. The result at that time was poor pedal feel. How much flex was there... don't know.

 

In this case I doubt it would even be measurable. Some material analysis in a computer simulation likely showed it. 

 

In practice, trying to reverse engineer a brake caliper with grinders, tape measure, or any tools any of us have access to won't reveal much. You could grind it off completely and likely never even notice; but there is that one scenario out of ??? that it would be a problem. 

 

Not sure what actual answer to the mystery you would expect to find that you haven't already - grind it off completely. Bolt it on and see what happens is all that's left. Unless we want to wait for the engineer to post his analysis and design of the caliper.

 

Not being a jerk or anything, just having a discussion about it.

 

No I completely appreciate this type of back and forth, it makes multiple minds work together. And by the back half, I meant the half without the rib. And yes, you are right, there's always that one time

[richard.bowen1]

Following this post closely. Im very interested in what JWEEZY finds out about the caliper once he cuts it in half. I have a 2019 High Country that I put aftermarket rims on and have to use .5 spacers, and it drives me nuts to see the different offset on the front and rear tires.

[jweezy]

11 hours ago, richard.bowen1 said:

Following this post closely. Im very interested in what JWEEZY finds out about the caliper once he cuts it in half. I have a 2019 High Country that I put aftermarket rims on and have to use .5 spacers, and it drives me nuts to see the different offset on the front and rear tires.

Sorry man, but you'll have to wait a few more months for this. I ended up having to deployed so I wasn't able to get that done. But I am definitely looking forward to cutting that caliper too. If anything, I would still feel safe grinding down half of that bump. But that still doesn't solve the issue of needing a spacer.

I was running a set of 3/8 inch spacers in the front at first with 2 inch spacers in the rear. That took care of the offset pretty good.

[repairman54]

Would GM add more metal to the caliper, which is more expense and casting complexity for no reason? No, they would not. That caliper rib is there for a reason. 

Removing it makes as much sense as notching your rims for clearance. Use a spacer.