New wheels = no brakes?
 

I recently installed BBS CH-R 19" wheels on my '01 Boxster S. I love the wheels, but I have noticed an alarming problem with them and wonder if there is a solution.

All of a sudden my braking has been greatly reduced. Cruising on the highway, when I need to suddenly brake for traffic, I have to use what seems like twice the leg power and wait for what seems an eternity for the brakes to grab.

The 19" wheels and tires are of course a few pounds heavier than my usual 17" setup. Could that be why my brakes are so slow to grab?

Or is it that the wheels are so much bigger, giving the brakes so much more cooling air, that whenever I want to use them they are "stone cold" and need to warm up a little on application before grabbing?

Or is it a combination of both? Or something else?

That's very odd behavior. Wheels that are a few pounds heavier should not effect a car with this much torque, or clamping force. Do you happen to know the exact weight difference including tires? You've moved more tire mass towards the outside, which at high speed will certainly be harder to bring to a stop, but if little econobox Hondas can run around with 20s all day, I doubt that is your problem.

Did you ensure the tire pressures are not jacked up to 40 lbs like they do at the mounting place? They will also need a few hundred miles to break in. If they are a hard compound, for longevity, it could be just a lack of grip compared to old tires. It's amazing to me when I upgrade tires on cheap non-performance cars how much more effortless the brakes get even at highway speeds. There'a a whole lot of friction going on at any speed. :)

Seems odd. Have you inspected your brake lines? May be time for stainless brake line upgrade? I have 19's on my 98 and braking performance feels the same.

My braking improved from 17-18" wheels. There is a larger contact patch now.

More likely the tires are to blame since they are larger diameter & heavier, increasing the "flywheel effect".

I would think that both are unrelated ==> check your brakes

There's no way wheels & tires caused that problem unless you put Monster Truck tires on it. Did the problem start at the exact same time the new wheels were installed? It could even be a brake booster problem.

Some more details:

Brake fluid is topped up. I flushed and changed to ATE Super Blue LAST spring. No brake problem for about 14 months.

I've got at least 1/4" of pad material (on the outboard pads, anyway). Do the inboard pads wear any faster than the outboard? I would think not.

Never seen any kind of brake-related warning light...I believe I have two, right? One light that would warn me of low brake fluid and one for low pad material?

I went from 17" Michelin Pilot Sport A/S Plus, which were excellent in every way, run from last fall, all winter, until just a few weeks ago. The new 19s are Michelin Pilot Super Sports, which, jeez, should INCREASE my braking power.

It really seems to me that this braking problem did not appear until AFTER I had more than 500 careful miles on the Super Sports, which is nuts!

Being brand-new wheels, with a lot of spokes, I have been cleaning them excessively with a LOT of dilute Simple Green and water. But jeez, I would think any slipperyness from residual Simple Green would be gone after one or two applications of the brakes.

Just before this problem arose, it is true that I did slather Black Magic Tire Wet dressing on the sidewalls, and the design of the Super Sports is such that they have VERY rounded "shoulders," and yeah, I did get some of this stuff on the first inch or so of the outboard shoulders, but...I have driven through a lot of rain since then, and it is hard to believe that the dressing is affecting the contact patch.

I dunno, it's weird. I step on the brakes and it's like nothing happens for a second or two. Then they start to grab. And the grab seems muted, only about half of what I am used to. It's like my pads are "glazed"?

I have to do something about this, though, because I commute on the Merritt Parkway in Connecticut (my own private Nurburgring when I am traveling in the opposite direction of the rush-hour jam), and it is common to go around a curve and suddenly come upon a sea of brakelights from stopped traffic. (This is literally a recurring nightmare I have, ha!) If I am lucky I have 50yds in which to go from 85mph to zero!

I think you have a brake problem. You've got good tires and appropriate wheels. If it was something with the tread surface, it would be affecting cornering as well. Has to be the brake system somewhere.

Brake problem. Put your original wheels back on and test. I'll bet you have the same issue.

Maybe you contaminated you brake pads in some way? Though I don't see how normal cleaners would do that. Pads often don't wear evenly, even on 4-piston calipers, so I would check them. Also check for sticking caliper pistons.

Bleed your brakes again

Must have spent a pretty penny on those CH-Rs... Post pictures

Just a side note, I wouldn't put simple green anywhere near those wheels. Are you diluting the stuff? I suppose it could potentially attack the compound on your brake pads too, but I've not heard about this before. People like to blame stuff on simple green, cause its used so much. It's really powerful though, so anything's possible if you sprayed it all over the affected area. What a stumper, though.

Have you tried braking really hard from speed to a stop? Maybe do that a few times, but overall, I can't think of how switching out wheels would cause this unless you altered the brakes, which if we get real technical, you did with simple green. If those are the only two things you've done, then it probably is one of those two things. If you had just messed with the brake system, I think we'd have a culprit. There's really no way those wheels could be causing THAT much additional effort to stop, especially with the compounds. If in 200 miles its not gone, something is definitely wrong. Some 19" tires are incredibly heavy though. You can increase your mass by a few lbs pretty easy among models, and being all the way to the outside, the effect is more pronounced. This probably shouldn't be underestimated in general when talking about performance, but your symptoms are not bad enough to warrant it as a cause.

+2 brake booster-- and at .25 inch of pad it's time to change them regardless
I wonder if you've got a brakeline anoreysm-usually these burst leaving you with practicly no brakes but maybe you have one that's just swelling under force. That's why I'm installing stainless- I don't want any BIG MOMENTS!!

Yes, the inboard pads can wear differently than the outboard pads (or vice-versa). In a perfect world they should be expected to wear the same but sometimes the world isn't perfect.

You can easily check the outboard and inboard pad thickness without removing the wheels by using a small mirror and a flashlight.

I'm just finishing a brake job on my car and found the pads were within about .010 inch end to end and inner to outer-I was amazed since I'm used to single piston designs which typically have a much wider tolerance.

Thanks
 

Some great ideas here, thanks, guys.

The CH-Rs were not outrageously priced, at least, compared to the cost of fully-forged BBS wheels like the LM or LM-R. My budget just wouldn't stretch that far. They have the advantage of taking OEM center caps, having a replaceable stainless rim protector, and of course, are BBS-quality. I like them a lot, although I would have gone for 18s instead of 19s if they were available.http://986forum.com/forums/uploads01...1369998361.jpg

What size wheels and tires? The tires really look stretched on the rim.

yeah - mebbe mark the rim and tire and see if it's spinning on the rim?

My sister's 99 Boxster's brake booster failed last year, leaving her without brake control, but it was the opposite effect. If she applied the brakes even lightly the pressure would sometimes hold like you were trying to put your foot through the floor, and they would not disengage for anything. Very unsafe, and I'm sure quite scary for her nearly getting stuck in the streeet not being able to move the car when the brakes did this.

I would think your booster may have just decided to give up the ghost around the same time you did the wheel swap, and in your case instead of the brakes locking up big time you're instead getting a delay in braking and a loss of braking power...failing closed instead of open, if you will, and not giving you the additional braking force it's supposed to.

I'm certainly no expert, but to me your issue doesn't sound like it's related to the wheel change. I think you're dealing with something strictly in the braking system.

And those wheels are quite nice.

A quick check to see if the brake booster is working is to put your foot on the brake - without the engine running. Start the car, keep you foot on the brake and you should feel the pedal depress as the engine vacuum pulls the booster diaphragm.
Its not foolproof, but a general check only......

False alarm, I think
 

Firstly, to answer the last couple of questions, the sizes are:

19x8.5 with 225/35R19
19x10 with 265/30R19

The tire sizes were the Tire Rack's recommendations, and the overall diameter is very close to the 17" overall diameter, so no speedo error, not that my speedo was that accurate to begin with...

And if the tires were slipping on the rims, I would think I'd be losing lots of air, and that's not the case. The Super Sports are funny-looking tires, with those rounded shoulders, I think that's what you are seeing.

I say my braking crisis is a false alarm, because I think the problem was ME. Or something boneheaded I did, anyway. I recently installed the 996 aluminum pedals, and to do this I hadda shove the seat way back. When I was finished with the job, I didn't bring the seat forward far enough, AND I also lowered the seat height. This changed my orientation to the brake pedal, and I just wasn't able to apply the same force I've been used to. Today I brought the seat forward where it should be, and whaddya know, my brakes seem to be back! I feel so stoopid about this.

But not as stupid as what ELSE I did today, which is rub one of my beautiful month-old CH-Rs against a Belgian block curb. Curse those Belgians! The stainless rim protector did it's job, and the wheel itself only took a tiny hit, but the protector is toast, in the way only stainless steel can irretrievably bend.

Now I hafta find out how to get a new protector on there. The Tire Rack told me that I could NOT buy extra protectors, since only BBS in Georgia would be able to mount a new one, but c'mon, it is just a metal ring clipped on and backed with foam tape. Shirley, they can't be serious. I guess I'm gonna find out.

If someone knows of a source for the ring (protector), please let me know.

And thanks so much for all your suggestions. If I manage to unconvince myself that the problem was just that my leg was having to stretch for the pedal, I will be following-up on them.

I think you should also change the pads is the pad material thicker than the backing plate?

A picture is worth a thousand curse words
 

Yes, Ckrikos, I have a quarter-inch or better of brake pads left.

Here's a pic of today's damage. It looks worse than it is in this pic. I can peel-off the protector without a problem I think. That foam tape is going to be a pain to remove, though. I have Goo-Gone, which works painfully slowly. The only REAL damage to the surface of the wheel can be seen under the curve of the wrecked protector.http://986forum.com/forums/uploads01...1370047549.jpg

Darn!

congrats for not blaming it on your wife!

LOL! Nah, it was all me this time. But the dent on the fender, the scratch on the nose, the chip on the console...those are all hers. Plus there is a faint smell of spilled coffee in the passenger footwell...

I've now removed the wrecked rim protector, and I was wrong, it is not clipped and stuck on with tape, it is actually only stuck on with the dreaded foam tape. I got the tape off with Goo-Gone worked-in with a toothbrush and a LOT of rubbing of gooey foam. Uck!

I've contacted BBS about buying some more rim protectors, waiting for their answer.

Just to be sure, I have now examined all my brake pads, and they all have plenty of material left.

Replacement on way
 

Just to finish off this thread, BBS in Georgia does indeed sell replacement rim protectors for $54ea plus shipping.

Can you share what offset you are running thanks...

Sure. The offsets are ET 51 Front and ET 38 Rear.

The rears are right on the edge of what I find acceptable (meaning that they are out from the car enough that if they were any further out they would stick out and I wouldn't like it.

The fronts seemed fine to me, and I ran them for a few weeks without any spacers, but I eventually put on 5mm spacers to get them to better match the rears, and now I consider their placement to be perfect. Can't say I noticed any difference in handling by widening the track by the 10mm. Using the spacers therefore becomes a purely aesthetic mod.