brakes

I've got a 92 ford bronco, the problem I'm having is when you apply the brake pedal you get a pulsating, up and down movement in the pedal and shakes the front end. About 4 months ago i had to change the front rotors because one of the calipers locked up,so i replaced rotors and calipers and front wheel bearings. So I always thought a pulsating brake pedal was a warped rotor, so if anyone has any ideas what the problem is I would appreciate the help.

If the front end is shaking and the pedal is moving its almost always warped rotors again , Driving habits directly effect how long they last /emoticons/[email protected] 2x" width="20" height="20" />

what kind of rotors did you put on it? typically new rotors recommend the same brand pads as well. so if you got cheapy rotors they would recommend their cheapy pads. I have a grand cherokee that is ******* rotors(all 99-04). People put OEM rotors and expensive aftermarket rotors and they still warp within 30k miles. I throw on the cheapest rotor i can find every year because i know it is going to warp again because there is no airflow around them to remove the hot gases created by the pads/friction.

The only other thing that could cause a pedal pulsation is possibly abs, but i dont think you have front wheel abs on that truck.

another thing is when you have new rotors pressed onto your hubs the shop needs to turn the rotors to make sure they are aligned properly. If they didnt do this you would most likely have one side of the rotor that is higher than the other causing added heat to one side. This doesnt take long to warp a rotor.

Warped rotors seems to be the recurrent response here.

I am certain that I have read that unevenly torqued lug nuts can warp a rotor.

AND I am pretty sure that someone posted on this site that he had bought new rotors and they were all warped, and after he bought his second set, he had them turned, and trued.

Another possibility is that one may have gotten some grease on the rotor. There are spray on brake and rotor cleaners, I don't know if they would be effective AFTER a brake pad got oily.

I put on a set of hubs and rotors from Carquest AUTO PARTS ON AND A $40 SET OF PADS ON FROM AUTO ZONE, I guess you can't turn the warpage out after it's warped

you can, even new rotors need to be checked because i doubt they check them when they press the rotors on the hubs. Some shops can turn them on the vehicle, some have to pull them. Id find a place locally and you can at least check them. The only way you can turn the warpage out is if you've had them turned a bit already. there is a min thickness requirement.

shift1313 said:

you can, even new rotors need to be checked because i doubt they check them when they press the rotors on the hubs. Some shops can turn them on the vehicle, some have to pull them. Id find a place locally and you can at least check them. The only way you can turn the warpage out is if you've had them turned a bit already. there is a min thickness requirement.

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Hey Matt,

I am really pretty sure that (at least on the '90 - '96 models) that the rotors don't have to be pressed on.

joe

hmm, can anyone confirm this?

this is what im familiar with.



and i know its that way on my 85,86 and 89.

OK.. so now you have me scratching my head.

I went to Autozone.com and checked for rotors for my '90 and this is what they said as a footnote:

Rotor only

Does not include center hub assembled with wheel studs Replacement requires pressing center hub out and back into the new disc

I never did them on our bronco, my son did, and before I posted I checked with him. HE said that he didn't have them pressed on.

I do recall, him being a little stumped in taking them off. I walked over with a BFH and with one good shot, and they popped off.

Maybe we got lucky?

By pressing they mean the lug nut studs once you knock them out the rotor will seperate from the hub rather easily . I have a big brass punch that I knock the studs back in with never had an issue 90% of the time you notice the pedal pulse after stopping really hard or towing something heavy its from the heat buildup . /emoticons/[email protected] 2x" width="20" height="20" />

yes but unlike a car or awd suv that uses the lugs to center the rotor sandwiched by the wheel, our trucks have them pressed behind the the hub using the studs. To remove them you have to pull all the locking hub guts out and the large nut(depending on year) that is ratcheting or has a jamb nut with a locating washer. The inner bearing is inside the back of the rotor along with the seal. The outter bearing is held in by the large nut. then behind the spindle there is another bearing and seal where the axle rides on.

Yes you can put a new rotor to your hub and assemble it but chances are it wont be centered perfectly. The only reason this is important is because the bearings are housed in the hub unlike other cars where the hub is separate from the rotor.

If your post was for me Matt Im very familiar with how the front end comes apart on these I used to get about 10,000 miles on a set out of my extended cab F150 because of my driving habits not because I bought cheapy or expensive brakes it didnt matter which I bought I tried both . The lug nut studs have splines on them where they go into the hole on the hub and the rotor that is the only thing that is a press fit if youve ever bought a new hub and rotor youll see that the 2 will go right together its not a press fit . You are correct that you have to take apart the enire hub assembly to get the rotor off the hub because its on the back side of the hub not like a dodge that is on the front side just like a front wheel drive car . You dont have to remove the back bearing or even the seal for that matter to change the rotor though . Thats all there is too it /emoticons/[email protected] 2x" width="20" height="20" />

I just called my local parts store.

He said that they carry the rotors, and could order and get a "full assembly" the next day.

He said that if one got just the rotors, one would have to knock the studs out, and then some people press them back in, and others just use a hammer. He said that it is recommended that one use new studs @ $2.13 each.

I understand what you are saying about possibly not being perfectly centered. Wouldn't five studs sufficiently center it?

Well I knew this had potential to turn into a debate of manuals so with my hands on manual I went to the garage where I had a brand new rotor for an 89 F150 and went behind the garage to the parts pile and grabbed a complete hub/rotor assembly from an 88 bronco . Now with my digital manual maker I went into the garage and in less than 5 min took it apart . Keep in mind I said I use a brass punch when I do this normally but being I had to hold the camera I just used a brass hammer and yes 5 bolts will center it just fine which with the ammount of clearance that the hub to rotor has and the shoulder on the bolt that is what it mostly centers on anyway . I have converted several full floater D60,s to disk by taking of the drum and putting a front rotor in its place . Works just fine /emoticons/[email protected] 2x" width="20" height="20" />

VIDEO1.MPG

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Hahahahaha... LOL man you had me ROTFL...

aren't you supposed to hit the studs with that BFHammer?

Nah... I guess you did with each stroke, but my video was playing faster than it could download it or something... thanks man, I hadn't laughed that hard all week!

LOL hey its harder than it looks . There a couple more coming with how easy they fit together sattelite is being really slow to upload right now sorry to everyone with dialup cant really shrink video files like you can pics atleast Im not sure on that one . Besides Joe I didnt hit the hub LOL /emoticons/[email protected] 2x" width="20" height="20" />

There the rest are uploaded . Does this seem helpful to anyone to see it come apart ? Could do this maybe for a T case rebuild but would have to find a way to shrink video /emoticons/[email protected] 2x" width="20" height="20" />

nope blade that wasnt for you i just typed it because joe said his son did the last set. I was just filling him in on what to do to pull them off since it's a fairly simple procedure.

And no the bearing/seal doesnt have to come out to swap rotors but if you are going to have them turned it does.

Yes you can just put the new rotors on the hub and hold them together with the studs and it may be lined up enough to work fine but it is also very possible that its slightly off. Ive gotten away with not turning them before but i always recommend that others have them trued when new rotors are put on the hubs just as a piece of mind(and cover my butt). Really in most cases you can have your rotors turned for less than the price of a new rotor anyways. Your video was a perfect example. The hub you pulled off had surface rust on it and was not a nice even machined surface anymore like a new unit. This is where the discrepancy comes from.

also the other reason i mentioned it is because alot of the parts you buy from the store arent perfect anyways. Ive purchased simple things like Idler pulleys that dont fit. The back actually contacts parts and ive needed to turn them down on the lathe to get them to work.

I fully agree with you and all you posted and if i put a new set of rotors on i probably wouldnt turn them but i have a lathe in my garage so i would chuck them up and see how close they were /emoticons/[email protected] 2x" width="20" height="20" />