Pulsing Brake Pedal - how do I tell which disc is warped?

[TerryTheSpyderRyder]

I seem to have a warped disk on my 2017 F3-S, but I'm not sure which one. It may be the rear as the trike doesn't pull when braking, there's just a pulsing uneven feel when braking. Is there as easy way to tell which disk is the culprit? Do they have a tendency to warp? I suspect the rear but I want to be sure before springing $200 for a new one. Thanks

[BertRemington]

What's the history on your 2017 F3-S. Miles? Original pads? One-up or two-up? Etc etc related to brake usage. It could be as simple as setting the parking brake at the end of a hard ride that used the brakes heavily. Doesn't warp the disk but does affect the rotor surface by leaving a "hot" spot. You might be able to resurface the rotor but probably easier to replace it. Otherwise get your dial gauge out.

[TerryTheSpyderRyder]

What's the history on your 2017 F3-S. Miles? Original pads? One-up or two-up? Etc etc related to brake usage. It could be as simple as setting the parking brake at the end of a hard ride that used the brakes heavily. Doesn't warp the disk but does affect the rotor surface by leaving a "hot" spot. You might be able to resurface the rotor but probably easier to replace it. Otherwise get your dial gauge out.

Not ridden hard, 15k miles on the trike. I suppose a shop would have to resurface the disk? Probably would cost almost as much.

[BLUEKNIGHT911]

I seem to have a warped disk on my 2017 F3-S, but I'm not sure which one. It may be the rear as the trike doesn't pull when braking, there's just a pulsing uneven feel when braking. Is there as easy way to tell which disk is the culprit? Do they have a tendency to warp? I suspect the rear but I want to be sure before springing $200 for a new one. Thanks

Mechanics would often pull the disc and put it on an ABSOLUTELY flat surface. Like thick glass .... then try and slide a piece of paper under it from all sides ...... this will tell you if it's warped and how bad depending on the number of sheets you can use ..... Good luck ..... Mike

[2dogs]

If it's a warped rotor try this. I know it works on a car because I've done it myself several times, but, I don't know if it works on a Spyder because I've never done it on a Spyder. Start out at low speeds and brake hard to a stop. Then take off and continue to increase your speeds and continue to brake hard to a stop but don't remain stopped. Build up your speeds to highway speeds braking hard and stopping. The idea here is to heat up your rotors to warping temps and then drive without any braking at all while you allow the rotors to cool down. It may pull the warp out of the offending rotor. You have to do your braking aggressively to make that heat build up. A straight long downhill road is the best place to do that if traffic will allow. Good luck and advise if it works for you.

[BajaRon]

I honestly do not think you are going to 'UnWarp' a rotor by heating it up. Nor is 'Resurfacing' a viable option. Any appreciable amount of material removed would put the rotor out of spec. Not to mention, a new EBC rotor would probably be less expensive and a definite upgrade to the OEM rotor.

However, many times a rotor exhibiting 'Warpage' is not actually due to warped steel. Instead, it is the result of an uneven buildup of brake material on the rotor face. Getting the rotor very hot then stopping with the brake pads clamped against the rotor can create a transfer of the resin material from the pad to the rotor. This leaves a deposit of material on the rotor that can continue to build up over time giving the impression that the rotor is warped (same pedal pulsation). Getting the rotor good and hot can soften the resin while strong brake application can squeegee the build up down. This might be an option to recover a rotor suffering not steel warpage, but a brake material buildup.

On another note. With all the EBC rotors I've sold to customers over the years. Some having warped up to 3 sets of OEM rotors. I've not had a single return customer (warranty) or complaint once they installed the EBC units. This, to me, is a pretty good indication that they work well. And they improve braking about 20% over OEM rotors.

[Cobwebs]

My experience with EBC rotors is they are a performance mod in their own right especially if combined with the HH pads so 2 for the price of one sort of deal if your shooting blind.
Just get a dial gauge and you'll soon find the culprit(s) and eliminate the guesswork.
Depends on your budget of course but a full set front and rear if you find a wobbly front would be the ultimate setup.
Or just fronts to save a bit of cash. If it's just the rear your choice stock or EBC.
The fact that you've warped a stocker should indicate that either your riding style or the quality of the stockers isn't consistent.

[2dogs]

I honestly do not think you are going to 'UnWarp' a rotor by heating it up.

You may very well be correct when referring to a spyder's rotor. I've never warped a spyder rotor so I can't say that it would or wouldn't work. However, it does work on a passenger vehicle's warped rotors. At least it does on my wife's car anyway. My wife is a poor driver and rides her brakes constantly. I was forever replacing her front rotors and I began using Summit's racing rotors to try and solve the problem. They didn't do any better. Complaining to a Summit parts tech about the problem, he gave me the info on how to unwarp my wife's front brake rotors using the heat'm up cool'm down method; and darn, it worked.

[Little Blue]

..I am curious about your Auto Rotors/Brakes. I have never tried to fix a Rotor in this fashion. It seems to me that maybe the Rotor had some material on it.
Did you check for run-out before doing the down-hill run?
Did you check for any mud or anything else on the rotors?

Stay Healthy. ....

[2dogs]

..I am curious about your Auto Rotors/Brakes. I have never tried to fix a Rotor in this fashion. It seems to me that maybe the Rotor had some material on it.
Did you check for run-out before doing the down-hill run?
Did you check for any mud or anything else on the rotors?

Stay Healthy. ....

We're sliding off topic here a little but here goes. I'm talking about clean rotors and pads here. To begin with, your vehicle rotor(s) will start giving off a slight frontend shimmy when they begin to warp. As they warp further the shimmy will increase. Most pronounced on long downhill grades. (Seldom felt in city driving.) This can happen on new and used rotors and most commonly (easily) occurs on low quality rotors. The cause is improper braking ie, riding your brakes over extended distances. Here's where it gets a little over my head. Metal has a memory when cast and manufactured into a product. Depending on the quality of the materials and manufacturing determines the performance of the product. However, even the best products (passenger car quality) have their limits of performance. Unfortunately, my wife's style of driving exceeds those limits. So, at the advice of the Summit parts tech, I carefully reheat my wife's rotors, and whatever memory that they came with or is left in them, they seem to return to their original shape because the frontend shimmy is significantly reduced. Hope this answers your question and doesn't offend our administrators. As for spyder rotors, I don't know if this would work.

[BajaRon]

One more thing to throw into the frying pan here. If your A-Arm bushings are worn. It can set up a front end wobble when the brakes are applied. This can mimic aspects of a warped rotor. Wobble usually goes away when you let up on the brakes. This is easy to check for.

[RazzleH]

If it's a warped rotor try this. I know it works on a car because I've done it myself several times, but, I don't know if it works on a Spyder because I've never done it on a Spyder. Start out at low speeds and brake hard to a stop. Then take off and continue to increase your speeds and continue to brake hard to a stop but don't remain stopped. Build up your speeds to highway speeds braking hard and stopping. The idea here is to heat up your rotors to warping temps and then drive without any braking at all while you allow the rotors to cool down. It may pull the warp out of the offending rotor. You have to do your braking aggressively to make that heat build up. A straight long downhill road is the best place to do that if traffic will allow. Good luck and advise if it works for you.

Works for me too. Thankfully occuring only occasionally. Whether it is simply cleaning the rotors or repairing warping I can't tell. However, my rotors are cleaned whenever I use brake dust cleaner, so I'm usually thinking it's warping. Whatever, thanks for the inputs on this one folks. Keeps old brains from warping too much as they ummmmm! where was I?

[2dogs]

Works for me too.

You did it on a spyder?

[RazzleH]

You did it on a spyder?

2020 F3Ltd.

[TerryTheSpyderRyder]

Thanks for your useful answer. My neighbor has a dial gauge and we determined that is is the rear rotor, as I suspected. Rather than try to fix it I'm just going to replace it. Thanks again.