Jack screw holes on front wheel rotors

I don't know if this has been posted before. There's no reference in any videos that I'm using for replacing the front brake hub/bearing assy.

But, as I am fighting the second caliper bolt on my truck, I noticed that there are two approx. 6mm threaded holes on the rotor on about the same B.H.C. as the 6 studs.

Are these to jack the rotor off of the hub?


TIA

 

They are probably 8mm x 1.25 thread
Yea they are for helping to get the rotor off but don't count on them if it's super stuck, there's not alot of thread there.

 

If you're replacing the rotors, just use a BFH until they come loose.

 

Leave the hammer in the tool box, don't beat on something unless there no better option. The jack screw holes work very well to remove the rotor and are designed specifically for that.

 

Wut?

Jokes aside, it's as Dm93 said. If the rotor hasn't been removed in the past 17 years, chances are the screw threads will strip. Most northern professional mechanics (professional as in time equals money) just use an air hammer in the areas between wheel studs.

The caliper bolts have loctite from the factory. Heat the bolts with a propane torch to melt the loctite and loosen while hot. It's advisable to apply loctite on installation, as a loose caliper bolt can break the hard brake line on the knuckle and dump out all your brake fluid.

 

It all depends on the rust, mine came off easily the first time after 17 years using the screw holes with zero drama but I don't live in a rust area.

 

^I imagine you don't grab the cutting torch as the first tool for removing U-bolts, either?

 

They are 6mm. I use grade 8 bolts and have used an impact gently to remove a sticky rotor. If a bolt breaks, you'll have to resort to percussive removal, but that's my last resort as that force goes right into the bearings.

 

U-bolts are a different story...and personally, I use the die grinder...it takes too long to get to my torches these days.

 

"jack it off! jack it off!" (the rotor, that is)

 

put grade 8 bolts at 3 and 9
Tighten the 2 bolts down and tap the rotor up and down
repeat again and again
Took me many rounds on my knees but i was able to get it off with persistence, like I always do.

 

No such thing as a grade 8 metric bolt. A class 8.8 (or higher) metric bolt is what you need.

 

I haven't come across a Toyota that is NOT 8mm x 1.25, but @ 17 years, it will all depend on the condition of the thread in the hole since there's not much thickness to the rotor there. Assuming decent threads, I haven't come across a better way yet to get them off - even compared to stuff like air hammering around the hub interface and using something like an OTC 6980 puller or similar.

 

Nope, I grab what's appropriate, I use abrasive cut wheel when I've needed to cutoff u-bolts, it worked like a charm.

 

If you're re-using the rotors, sure be gentle..

If you're replacing them just bash those fuckers off. You're not going to hurt anything at the wheel hub

Skip the loctite at the caliper bolts, it'll just make it harder on the next guy. If you need that stuff to keep bolts tight you shouldn't be wrenching on cars

 

Thanks for all of the replies.

I finally got the last caliper bolt out with a 3 foot pipe extension on my breaker bar. I had to use a wrench to the entire length of the thread. Even after cleaning, the bolt is a tight fit.

And, the 2 jack bolts worked like a charm, 1/4 turn at a time... fortunately no rust between the rotor and the hub.

I'm put a light coat of anti seize on the caliper bolts since they're thru holes and backed off 5% on the torque to compensate.

 

He jacked it off! Hooray! (the rotor)

 

It's all semantics. Some of these guys like Beating it off, better. (The rotor)

I just don't like to pay for the same part twice.

 

I've done it both ways, and jacking just feels better.

 

My PERSONAL observations, living in New England, is that rotors don't rust to the hub at the FACE - even if there's rust. From what I have experienced, the rust forms between the hub center and the rotor, where the rotor sits on the hub.

The rust forms at that point, and consumes any minuscule gap there might be via rust jacking causing a large amount of pressure between the center of the rotor and center of the hub.