What is the Bolt Hole Circle Diameter on the
Rotors of a 1998 Bonneville SE?
I am measuring about 4.625" Dia.,
is this right or is the Standard GM Bolt Hole
Diameter 4.500" Dia. for the Bonneville ?

Thanks,

Luke

the bolt pattern is 5x115

Thanks 1993 SLE ....

I am tired of the Rotors Warping on this Car every 5000 miles or so. So
bad it shakes my front end. Just put on new ones from NAPA (the only ones they offer - from China -- Cheap Junk!) and they are already Warped. Yes, I torqued them, 60lbs, then 80lbs, then the final torque of 100lbs., all in a star pattern.

So I am going to turn then myself and add (machine in) either holes or slots to see if it will help stop warping these rotors.

Any advice to corect this problem would be great.

Thanks for the reply.

Luke.

Others with warping problems have added wire brushing the surface the rim makes contact with, checking the rims and then wd40 on the studs overnight to ensure they are clean and all torque equally.

As well you may want to check your calipers and slides to make sure they are returning properly and not sitting up against the rotors causing extra heat.

If you drill or slot your own rotors you will have major problems. Very expensive major problems.

Quit buying cheap rotors and get powerslots (with the correct pad) or rsm rotors, which I run.

Luke unless you are a machinist you will probably run into more problems than success with drilling/slotting rotors on your own. The slotted and drilled rotors are harder compound to deal with the structural changes.

The specs to keep from chewing up pads and causing braking issues are far greater than the benefit of the cooling you might get from them.

I am running a standard rotors and am tough on my stuff. Before you aim to drill or slot.... lets discuss a little further. There'* most likely a very understandable reason for the warping that will keep reappearing with any rotor.

Do you find yourself riding the brakes? Do you have a lot of hills in your area.? Quick stops where you are pushing hard on the brakes?

The questions I've posted above are aimed to find out what is causing the heating of the rotors beyond normal. That heating or something as mentioned above (cleaning with wire brush) is probably the reason for the warping.

To give a further example. I don't seem to warp rotors, and I am extremely harsh on my brakes. I do quick stops, I end up in stop and go traffic....etc. I don't have warping issues though.

Guess what I'm trying to say is I believe there is an underlying issue that is causing your warping and why do all the work to rotors or continually buying to keep having the same problems.

If you modify your rotors and they explode on you (don't make me go into a lecture on thermal dynamics and mettalurgy), your insurance company will disown you and you'll be liable for all damages.

Drilled rotors are ONLY appropriate when the holes are CAST into the blanks, not drilled later. Slotted rotors are far more effective on street cars.

Be very careful in your selection of components, and you won't warp rotors. Be anal about cleaning the lug studs and oiling them before torquing, as well as cleaning the mating faces of the hubs and rims.

[quote="willwren"]If you drill or slot your own rotors you will have major problems. Very expensive major problems.

willwren, when you say major problems, what are you referring too? Aren't the Powerslot rotors just rotors with slots in them (better rotors to start with I am sure before slotting)? What will makes the slotted rotors I machine
so different (besides starting with a cheap rotor - checp iron!)?

Thanks,

Luke

Home drilled/slotted is a very bad idea.
Properly done rotors are drilled or slotted as part of the casting or machined into the raw unfinished blank. They are then machined heat treated and finish machined to final dimensions and for balance.

The holes and slots are also chamfered to the wear limit to prevent the cheese grater effect on the pads.

If not done correctly they will have a high probability of catastrophic failure. (They will explosively disintegrate)

If this happens and causes an accident your insurance company will just laugh and walk away. You then get to deal with the local DA and the tort lawyers.

Please do not drill or slot rotors yourself.