Drilled Rear Drums
06-18-2009, 01:29 PM
#1
Seasoned Member
Thread Starter
Join Date: Mar 2009
Location: I'm bad, I'm nationwide.
Posts: 397
Likes: 0
Received 0 Likes
on
0 Posts
Year: 1996
Model: Cherokee
Engine: 4.0
Drilled Rear Drums
Would drilling the rear drums have any effect on braking? I know that the drums are huge and are ribbed to let out heat. I know that your rear brakes do not do the lion's share of braking but if I am baking down a steep incline I'd like to help those measly drums out as best I can.
06-18-2009, 01:37 PM
#2
Member
Join Date: May 2009
Location: Richmond, VA
Posts: 137
Likes: 0
Received 0 Likes
on
0 Posts
Year: 1991
Model: Cherokee
Engine: 4.0 I6
Where would you drill them? All drilling on the outside circumference would do is reduce the amount of surface area that the brake shoes have to rub against, which would get you less braking power. I couldn't see where drilling holes in them would be any kind of benefit at all. Really, unless you are in a hardcore racing environment, cross drilled brake rotors are nothing but a fashion statement. They really provide no benefit to a street driven car, and just like drilling the brake drums would do, they provide less surface area for the brake pads.
06-18-2009, 01:58 PM
#3
Seasoned Member
Thread Starter
Join Date: Mar 2009
Location: I'm bad, I'm nationwide.
Posts: 397
Likes: 0
Received 0 Likes
on
0 Posts
Year: 1996
Model: Cherokee
Engine: 4.0
If you drive an import that weighs 1000 lbs they are a fashion statement. My other vehicle is a ford excursion and I do a good amount of towing. THe rotors I purchased for it I feel were crucial. Cross Drilled and slotted rotors are proven to keep the braking surfaces cooler and release the gasses that result in braking. If they were crap they wouldn't come stock on high-end sports cars.
I do a lot of hill climbing and sometimes I just don't pick the right way up and turning around on something that steep is retarded so I back up. The engineer who designed my wonderful cherokee did not design it to do its major braking in reverse so when I have to depend on those drum brakes I'm all puckered up if you know what I mean.
Obviously I would drill the surface where the pad meets the drum from the outside with a drill press then have the drums turned.
My original question was do you think this would hinder or help brake effeciency? Going forward I don't think I would ever know the difference but rolling back ward down a hill?????
I do a lot of hill climbing and sometimes I just don't pick the right way up and turning around on something that steep is retarded so I back up. The engineer who designed my wonderful cherokee did not design it to do its major braking in reverse so when I have to depend on those drum brakes I'm all puckered up if you know what I mean.
Obviously I would drill the surface where the pad meets the drum from the outside with a drill press then have the drums turned.
My original question was do you think this would hinder or help brake effeciency? Going forward I don't think I would ever know the difference but rolling back ward down a hill?????
06-18-2009, 02:47 PM
#4
Junior Member
Join Date: Jun 2009
Posts: 86
Likes: 0
Received 0 Likes
on
0 Posts
Year: 96
Model: Cherokee
Engine: 6cyl
Cross drill rotors are completely for show.
Highend auto companies use the, because the puplic assumes they are getting the best. Why argue with your customers
There is less coverage, there for there is less space for the heat to go.
They actually should get hotter, if heavy breaking is acurring.
Lets also not forget the fact if you have them on your truck and your spending alittle time in the mud. Small rocks get caught in them and kill your pads
Directional vented breaks on the other hand do what they say they do.
Thats why race teams use them.
Highend auto companies use the, because the puplic assumes they are getting the best. Why argue with your customers
There is less coverage, there for there is less space for the heat to go.
They actually should get hotter, if heavy breaking is acurring.
Lets also not forget the fact if you have them on your truck and your spending alittle time in the mud. Small rocks get caught in them and kill your pads
Directional vented breaks on the other hand do what they say they do.
Thats why race teams use them.
06-18-2009, 04:04 PM
#5
Member
Join Date: May 2009
Location: Richmond, VA
Posts: 137
Likes: 0
Received 0 Likes
on
0 Posts
Year: 1991
Model: Cherokee
Engine: 4.0 I6
Cross drill rotors are completely for show.
Highend auto companies use the, because the puplic assumes they are getting the best. Why argue with your customers
There is less coverage, there for there is less space for the heat to go.
They actually should get hotter, if heavy breaking is acurring.
Lets also not forget the fact if you have them on your truck and your spending alittle time in the mud. Small rocks get caught in them and kill your pads
Directional vented breaks on the other hand do what they say they do.
Thats why race teams use them.
Highend auto companies use the, because the puplic assumes they are getting the best. Why argue with your customers
There is less coverage, there for there is less space for the heat to go.
They actually should get hotter, if heavy breaking is acurring.
Lets also not forget the fact if you have them on your truck and your spending alittle time in the mud. Small rocks get caught in them and kill your pads
Directional vented breaks on the other hand do what they say they do.
Thats why race teams use them.
Here are a couple of quotes from a whitepaper written by StopTech, a company that makes high performance brake parts.
DRILLED VS SLOTTED ROTORS For many years most racing rotors were drilled. There were two reasons - the holes gave the "fireband" boundary layer of gasses and particulate matter someplace to go and the edges of the holes gave the pad a better "bite".
Unfortunately the drilled holes also reduced the thermal capacity of the discs and served as very effective "stress raisers" significantly decreasing disc life. Improvements in friction materials have pretty much made the drilled rotor a thing of the past in racing. Most racing rotors currently feature a series of tangential slots or channels that serve the same purpose without the attendant disadvantages.
3) Repeated hard stops require both effective heat transfer and adequate thermal storage capacity within the disc. The more disc surface area per unit mass and the greater and more efficient the mass flow of air over and through the disc, the faster the heat will be dissipated and the more efficient the entire system will be. At the same time, the brake discs must have enough thermal storage capacity to prevent distortion and/or cracking from thermal stress until the heat can be dissipated. This is not particularly important in a single stop but it is crucial in the case of repeated stops from high speed - whether racing, touring or towing.
AIR COOLING Most of the enormous amounts of heat generated during deceleration must be dissipated into the free air stream.
Most high performance (and/or heavy) cars today use some variation of the "ventilated" brake disc in which air entering the center or "eye" of the rotor is forced through the interior of the rotor by the pumping action of the rotating assembly. The most efficient practical way yet devised to accomplish this is through the use of the "curved vane" ventilated brake rotor originally designed for the LeMans winning Ford GT 40s in 1966. In this design the interior vanes are curved to form an efficient pump impeller. They also stabilize the rotor from distortion and serve as very effective barriers to stop the propagation of cracks due to thermal stress.
Most high performance (and/or heavy) cars today use some variation of the "ventilated" brake disc in which air entering the center or "eye" of the rotor is forced through the interior of the rotor by the pumping action of the rotating assembly. The most efficient practical way yet devised to accomplish this is through the use of the "curved vane" ventilated brake rotor originally designed for the LeMans winning Ford GT 40s in 1966. In this design the interior vanes are curved to form an efficient pump impeller. They also stabilize the rotor from distortion and serve as very effective barriers to stop the propagation of cracks due to thermal stress.
06-18-2009, 04:17 PM
#6
CF Veteran
Join Date: Nov 2008
Location: Oak Harbor, WA.
Posts: 6,989
Likes: 0
Received 4 Likes
on
4 Posts
Year: 1987
Model: Cherokee
Engine: 4.0 liter RENIX I-6, DIY Cold Air Intake, 2.5 FM Exhaust, 3 Core Radiator
I'd still like to ditch the stock drum brakes on my rear D44 in favor of discs....even without the pretty drilled and slotted rotors.
06-18-2009, 04:34 PM
#7
Senior Member
Join Date: Jan 2009
Posts: 920
Likes: 0
Received 1 Like
on
1 Post
Year: 1996
Model: Cherokee
Engine: 4.0
i dont think it would do much to help braking it might help keep a little cooler but probably not noticable if you want to get better braking get disk brakes for the back that would be very beneficial
Trending Topics
06-18-2009, 04:50 PM
#8
Seasoned Member
Thread Starter
Join Date: Mar 2009
Location: I'm bad, I'm nationwide.
Posts: 397
Likes: 0
Received 0 Likes
on
0 Posts
Year: 1996
Model: Cherokee
Engine: 4.0
hrmmmm.........
Is this one of those in your opinion things or are regular rotors better.......
I was just looking for a way to help the old drums out till I got the time/money to do the conversion to disc.
Is this one of those in your opinion things or are regular rotors better.......
I was just looking for a way to help the old drums out till I got the time/money to do the conversion to disc.
06-18-2009, 04:56 PM
#9
Senior Member
Join Date: Jan 2009
Posts: 920
Likes: 0
Received 1 Like
on
1 Post
Year: 1996
Model: Cherokee
Engine: 4.0
hey its pretty much free never hurt to try but rotors are definitely better just think never have to worry about mud and dirt getting stuck in your drums ever again and better braking
06-18-2009, 05:22 PM
#10
Junior Member
Join Date: Jun 2009
Posts: 86
Likes: 0
Received 0 Likes
on
0 Posts
Year: 96
Model: Cherokee
Engine: 6cyl
There more or less just a waist of money.
Directional vented rotors are the wait to go if your concened about heat.
Not great with mud though.
Swaping the back out is the way to go, but the kits are too pricey imo.
Junk yard is where it's at.
06-18-2009, 08:01 PM
#12
Junior Member
Join Date: Mar 2009
Location: Western Colorado
Posts: 95
Likes: 0
Received 0 Likes
on
0 Posts
Year: 1988
Model: Cherokee
Engine: 4.0l
06-19-2009, 12:31 AM
#13
Senior Member
Join Date: Dec 2008
Location: Aldergrove,BC,Canada
Posts: 564
Likes: 0
Received 0 Likes
on
0 Posts
Year: 1989
Model: Wagoneer
Engine: 4.0L I6
exactly if it was beneficial it would have been done all ready and like others have said the amount of crap that would get stuck in there would be increased
i dont even like the idea of slotted/drilled rotors on 4x4s cause of the amount of crap that can get stuck in them
BTW you think you got bad brakes try driving an 80s XJ they suck when stock when i get time and money im doing WJ brake system its sposed to be a world of difference.....apparently it stops when you push on the pedal not 10' later
and if ya really wanna get into it swap in wj calipers...but again more time more money
06-20-2009, 02:34 AM
#14
Member
Join Date: Jun 2009
Posts: 114
Likes: 0
Received 0 Likes
on
0 Posts
Model: Cherokee
Where would you drill them? All drilling on the outside circumference would do is reduce the amount of surface area that the brake shoes have to rub against, which would get you less braking power. I couldn't see where drilling holes in them would be any kind of benefit at all. Really, unless you are in a hardcore racing environment, cross drilled brake rotors are nothing but a fashion statement. They really provide no benefit to a street driven car, and just like drilling the brake drums would do, they provide less surface area for the brake pads.
Adjusting the rear brakes on most any jeep completely changes everything. Just do it.
06-20-2009, 03:19 AM
#15
CF Veteran
Join Date: Feb 2009
Location: socal
Posts: 7,244
Likes: 0
Received 0 Likes
on
0 Posts
Year: 2000
Model: Cherokee
Engine: 4.0
this is why i went to disc in the rear. some of the trails i wheel on i need reverse and the drums where not cutting it. when ever you can swap to disc. think of it this way why spend 200 to rebuild crappy drums when if you spend 400 you have disc and way better stopping. plus it is much cheaper to service the disc then drums when the time comes 