Making your own cross-drilled rotors
 

Hey guys,

I was wondering if anyone had any input on me cross drilling my own rotors?

What I have at my disposal is a complete set (front + rear) brake rotors for my '85 Volvo 240GL. Cross drilled for that car are hard to find and expensive, plus I have a full set that's just hanging out that I recently stripped from a salvage car (for free). The fronts are vented and the rears are solid, I was thinking of maybe finding a template, then drilling at specific points (yes I know it has to be balanced since the tire spins pretty fast).

The front has 4 piston calipers, the rear has 2 piston calipers (hey this car weighs 2 tons). The most money I would be out of (aside from trashing the rotors) would be having the machine shop resurface them ($7 per rotor). Yeah I realize I could goto the auto parts store and save a buck or two on turning, but then risk having them screw it up. Plus I like the machine shop I've been using, shall send all my business to him.

Call it ghetto, call me stupid - if anyone has heard of this kinda thing working and know the process, hook me up.

Thanks.
-Ryan

Re:Making your own cross-drilled rotors
 

wow, 21 posts and you already have come up with something I want to try if you don't ---- up. You're one of my favorite noobs so far.

I don't know what kinds of things go on with the factory cross drilled rotors, hopefully someone else does.

Re:Making your own cross-drilled rotors
 

don't experiment with your life. Its a good thought but leave the saftey components to the engineers

Re:Making your own cross-drilled rotors
 

I've actually been hitting this site on and off the past 3 years, started my membership a year ago, only recently I've been posting on quite a few threads.. I dunno boredom?

I've been doing crazy things to cars for the past 10 years, if you read my other posts you can tell I don't talk like a noob, I rarely mispell words and I don't say stupid ---- like "dat wud be so tite dawg!"

But thanks anyways for the comment, if I get enough research done and do attempt the project, they are gonna get thrown on my dad's car - 240 Wagon (maybe without him even knowing LOL) since he does a good bit of highway driving and I normally drive my truck (4x4 action baby).

Re:Making your own cross-drilled rotors
 

wow, i guess you were writing that when I was writing my last post, else I would have acknowledged this in my last one.

Yes, you are so right on that one.. might just get them turned and say the hell with it. I ran the idea by my brother the other night, he said not to try it and "I saw on speed vision where they said not to do that" but then again I never have taken his automotive advice into consideration in the past (it's always me the one working on HIS car.. stupid DSM).

I wouldn't be worried about the structural interference issues, when they make cross drilled rotors it's just a cnc machine cutting at exact specs. One time when I was working parts counter for an auto parts store this guy came in with a front rotor that was wore all the way down to the slotted fins (in the center) - no meat left, I think it was on an 80s full size pontiac. All he could say was "tell everyone it was a woman driver" I hung it on the wall for a while until my boss threw it out. I thought it was a good business ploy, make people want to buy more brake parts from us ::)

So knowing that the metal could withstand the drilling of holes at certain points, the weighing factor would be positioning the holes in such a way that it doesn't offset the balancing of the rotor that is spinning at a good rate.

I guess this one is still in the air for me, but if anyone else has any input, please share.

-ryan

Re:Making your own cross-drilled rotors
 

a friend of mine did this on his dodge dakota.. actually, he had a professional(close friend of his) do it. when i first saw it it looked perfect. however, its been a year and a half now and there are tiny cracks just beginning to develop around the drilled areas. it was good for a while, but obviously it isnt meant to last long. :-\

Re:Making your own cross-drilled rotors
 

that reduces the serface area. get slotted. they just as good.

Re:Making your own cross-drilled rotors
 

cross drilled rotors crack...Even seen cracked ones on Porshe's. And they come with them OEM...I think slotted are better though or just get a bigger rotor.

Re:Making your own cross-drilled rotors
 

yeah you need to be careful, they crack when you do them yourself (not sure about high quality drilled rotors) i have heard that slotted is better

Re:Making your own cross-drilled rotors
 

well, i'm not sure if you're going for looks here, but a simple way to keep it balanced would be to just follow the simple little rule of algebra, 'whatever you do to one side, you have to do to the other'. just do one hole at a time and then go exaclty opposite of it nad work it in a good pattern. :-\

Re:Making your own cross-drilled rotors
 

I had cross drilled and slotted rotors on my GS-T. I thought they worked well, but I sold it so I dont know how they held up.

Re:Making your own cross-drilled rotors
 

yeah, i heard about the guy that bought it, he was killed in a crash due to brake failure :-\ ;)

Re:Making your own cross-drilled rotors
 

I dont really see slotted or drilled rotors giving more braking force. if anything less.. less surface area.

also the slots and holes will just end up eating the pads unless you get like kevlar or metal race pads. (which will be WAY WORSE for street driving as they wont get hot enough).

think about it, the slot is going to slice into the pad on every revolution.

if you ask me, get some bremo blanks w/ good pads and you'll be set. slotted/drilled rotors are ricey in my book.

Re:Making your own cross-drilled rotors
 

the slots and holes are there to disperse the heat that is absorbed by the rotors during breaking, cooler rotors = better breaking, very funtional ;) have you ever noticed the ends of brake pads have an angle on them? as long as you get the rotor turned after you do it to make sure there's no debris that is above the level of the rest of the rotor the pad's slide right over it.

Re:Making your own cross-drilled rotors
 

they disperse heat but the main function is to vent hot gases/vapors from the braking surface because the materials break down at thousands of degrees and the vents (slots or cross drilled holes, even dimples) keep the surface of the pad pressed more firmly against the rotor by venting the surfaces between it and the rotor... it does the job well. Yea some, especially slotted rotors, wear pads faster. Id give up the pad life for the brake performance tho...

Re:Making your own cross-drilled rotors
 

if you have that much gas between the pads/rotors you're using the wrong pad compound for your driving.

and kevin, the angled edges of the pads eventually wear down.. smart ass ;)

go look at super cars. all blanks.

Re:Making your own cross-drilled rotors
 

it's still level with the rotor, i don't see how you think it's gonna 'slice' into the pad. go look at auto-x cars, all slotted ;)

Re:Making your own cross-drilled rotors
 

yeah it reduces fade and the brakes bite harder when you get into them... just get some and drive around, you def feel the difference. Any gas between the rotor and the pad reduces its efficiency

Re:Making your own cross-drilled rotors
 

If you ever look at real race cars ie Cart/GT cars...They have 100% solid disks. They just use a thicker disk...

I set of Brembo replacement rotors isnt that much (solid too) so why bother?

Re:Making your own cross-drilled rotors
 

thats because they are braking from 200mph and cant sacrafice structural integrity... plus they are really light

Re:Making your own cross-drilled rotors
 

i have cross drilled all my rotors on both my sol and my talon and have had them for almost a year, and i have no problems whats so ever.is it worth it?Not really a big change, id save the time and cost and buy a big brake kit.

Re:Making your own cross-drilled rotors
 

wow, we got some pretty good discusion going on in here, I thought it was just going to by my lame ass posts followed by a few "ur dum" comments.

I want to do autocross so I'm more inclined to get the slotted rotors, but I can't quite decide. good thing is I don't have money for brakes right now.

Re:Making your own cross-drilled rotors
 

I'd be more inclinded to slot my own with the right equipment. I know someone that did it and it worked fine. I've been running powerslots up front for about 3 years now and so far I've gone through about 3 sets of pads, but the rotors are still in good shape.

Re:Making your own cross-drilled rotors
 

I really didn't expect this kinda turn out, but hey a lot of good points.

I'm not going for the rice look on this car, it's a ------- volvo.. an older one at that, it would be impossible to rice it out.

I'm not trying to go for more power stopping either, granted this car is pretty damn heavy the brakes on it will throw you thru the windshield, they are extremely touchy and very very strong - I'm very pleased with the way they work stock. A big brake upgrade is virtually impossible for me to do, the car comes stock with 4 piston front/2 piston rear calipers. Bigger rotors are pretty much out of the question too, the lug pattern on that car is so specific, it only shares it with the other 200/700/900 series volvos and all of them pretty much have the same brake setup. Yes the 850/V series have a similar lug pattern but that would take some fabrication to get one of their rotors to fit since the offset is way off.

So no, I'm not going to go out and buy a brembo brakes for one of my volvos that have over 200k miles on them, stock brakes work fine and the cars definately aren't show vehicles.

My quest here was to just give cross drilling a shot since I yanked the complete braking system (and every other imaginable part) off of a wrecked '87 240GL that the tow truck driver said I could have (personal friend of mine). A good point was made right after I started this thread by whitey saying that it's very unsafe. That was an excellent ------- point! I currenty live in the ozark mountain range and the more I think about it, the less likely I'm going to do it. That would suck so bad if I was coming down a really steep mountain pass and the brakes failed on me, one thing to have a master cylinder go out when you are driving on flat ground (which has happened twice to me on 2 other volvos I've owned), another to have your front rotors ---- out cause you were stupid and decided to ---- with a good factory product.

But the feedback I've gotten has been pretty good, maybe when I move back to florida and drive the volvo I have in storage there (my favorite one) then I might attempt the project (I'm sure I'll still have this extra set of rotors to play with).


I think the cracking of the rotors on a DIY job might be from the stress of the drill going into the rotor, a properly engineered and machined rotor should not crack during normal life/use. Cutting slots sounds a bit tricky, might just say screw that and only go for the cross drilled effect. I would think the only thing one would need would be a template to follow for the drilling pattern, basic math in effect. I wouldn't do something like this on a ghetto level, I would be using my drill press and whatever proper tools to make it work, if I do attempt it; expect a write up ;)

My brother recently got cross drilled on his eclipse and I have a friend who just switched over to drilled/slotted on his '02 trans am.. only time will tell if those rotors hold up (both are ebay purchases :-\)


-ryan

Re:Making your own cross-drilled rotors
 

god damn you make long posts :P ;)

Re:Making your own cross-drilled rotors
 

I read a story about this guy who worked at a track, and this dude came in with a volvo or something with home made cross drilled rotors, anyway, One of the rotors broke into like 100 pieces and the other rotor hat tons and tons of small cracks in it. But the thing was the rotors had like 100 holes in the each, there was way too many holes and that totally reduced the integrety

If i were stupid, I would drill maybe 4 holes per rotor, but not more than that. and i don't see why you wana put cross drilled rotors o na damn volvo, wtf.

Re:Making your own cross-drilled rotors
 

The volvo braking system is not prone to failure, it's actually quite advanced in comparison to import/domestic systems of it's era. I wouldn't put that many holes in it, use a 1/4" (or smaller) drill bit - something that wouldn't break on me hundred times before the job was done, but also something small enough to make small sized holes. I would get a formula kickin, just do a proper pattern, I can't tell you the design right now, not that close to the project yet.

As I illustrated in a couple posts on this thread, I have a full (4) set of rotors that were free and just hanging out on my front porch right now (awaiting sand blasting, then going to get a nice high temp coat of black paint). I wanted to try something new, Jeff and Whitey put twin turbos on their rides, my claim to fame might be cross drilling some rotors (well maybe not, but it was a good effort). Nobody is going to see these rotors past the stock rims (if I had some thin spoked chrome rims, that would be a diff story), I'm not going for the "look" at all. The basic performance of these brakes is far superior to any other car I've been in, I've pleased with the way they work stock. Soo, I have the resources (4 functional rotors), I have the right tools, I have the time.. just thinking of giving something new a shot. That's all.

-ryan

Re:Making your own cross-drilled rotors
 

ask any of the ladies, my posts aren't the only thing that's long ;D

Re:Making your own cross-drilled rotors
 

Thats funny.The site has only been aroung for about 1 1/2 years.

Never asume that anny car is rice proof!

Just buy some dude.Why risk dying?

Re:Making your own cross-drilled rotors
 

Seriously.....

I had dilled rotors on my old Civic with the same set of brake pads for like 4 years. I have no ------- idea how those brake pads lasted so long. They were VGX pads with some cross drilled rotors I got from Summit back in the day. I am a firm believer in cross drilled rotors. I have a set of drilled/slotted rotors for my hatch and my truck needs brakes BAD, so I'm getting a set for that too. It seems to work good for me.... :-\
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Re:Making your own cross-drilled rotors
 

Verry true Doc....come to think of it I havent changed my pads in like 2 years!Bremro 0wNeZ 8)

Re:Making your own cross-drilled rotors
 

Um, the website has been around longer then that, are you referring to the forum?

I've seen quite a few 240 volvos, I seriously doubt there is one that has been disgraced to that level, mostly old conservative white people drive them

Huh? Safety is more important then performance in any car, in the area I live in brakes are really important.. this cross drilling was only a thought, i may test it at a later time. I still wanted the feedback from people who might have already done it.

Re:Making your own cross-drilled rotors
 

Ryan, I have alittle tip for you, DON'T FIX IT IF IT'S NOT BROKEN! it's a volvo man, it's not fast, it's not cool, and having slotted brakes does ---- for you really. I'd understand if you were gona auto-x your car or race it, but since the brakes are fine and they work awesome then why ------- risk it man.

actually waht I said was just hopiing on the bandwagon :P
Drill the rotors, don't drill very many holes, you don't need many at all, what will kill you is the size amount of the holes. also, when drilling don't put any force on the drill bit, let it do all the work

Re:Making your own cross-drilled rotors
 

what is needed is stopping power. not gas venting. sure its important. but not on a street vehicle. i mean do you ride on your breaks the whole time untill they glow red??? nope. so why would you need something to vent gasses? ---- my stock rx7 breaks like none other. i could slam on the breaks going 100 and not get any tire squeel. it will just stop.


and yes, volvo's ( up to a certain year and then back again ) are superior cars.


what should be discussed is the lines, the pads, the pistons # and the master cylendar. because all this makes you stop better. just putting slotted rotors wont make your car stop better. its all about gripping force.

but like i said, its about racing. since porches have them because they where designed for highway ( autobahn wink wink ) use. not inner city use.

Re:Making your own cross-drilled rotors
 

guys you're missing my point here, yes i know what the car is, i know it's limitations, i know it from the inside out. The car as is suits me fine (be nice to swap in an sbc instead of that tired old slat 4), but I wanted to experiment, I have an extra set of rotors, figure I would try to cross drill them myself to see how it goes.. just wanted to know if anyone else has done the same thing.

Re:Making your own cross-drilled rotors
 

Very well put, i definately agree. Cross drilled and slotted are nice qualities of brakes if they are done right. Depending how well the holes are drilled and how far and by who, it may be a very very very long time before they crack if they ever do. Upgrading rotor size will give u the most breaking power along with bigger calipers of course.. the more pistons in the calipers help a bit too.. but moreoever they make the braking smoother. P.S if you want more info on how to do the cross drilled, i can tell u, i live at the machine shop, pm me