Drilled Rear Drums
CF Veteran
Joined: Jun 2009
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From: Michigan
Year: 1987 MJ, 1973 J2000, 1986 XJ, 08 JK
Model: Comanche (MJ)
Engine: 4.0L H.O
You're kidding of course. That drum brakes were too good? How old are you?
Go back only to the 60's Drum brakes overheated on any decent grade, then splash thru a puddle getting one btake wet and the next brake application slews you into another lane. Simply getting them adjusted so the car would stop in a stright line was difficult at best and sometimes it could not be done at all.
Chrysler came out with "center-plane" Drum brakes that were fantastic! The trouble was even with the complex adjusting rig needed to properly adjust the things the adjustment never lasted over a few miles.
In Europe, AlFin made the biggest, baddest alloy drums ever seen and they failed to cut the mustard. In 1956 Jaguar showed up at Le Mans and blew everyone into the weeds with Disc brakes and no one ever looked back. End of story.
Except for Jeeps hanging on the side of a hill. There its nice to have drums on the rear to ease back down as most rear disc setups have a rather small parking drum.
Freakaccident has it right. Maunally adjust the rear drums to get them to work properly. The built in adjusters leave a lot tp be desired.
The single piston caliper on Jeep front ends tends to **** in the bore and jam there when panic braking and 12 feet pressing down on them won;t even slow the damn thing down. This is personel experence talking here. I now have 11" slotted rotors and 2 pot, twice as big as stock, calipers on the front of my XJ. Thats where to spend your money. On the rear adjust the drumsso tight you can't move the tire at all then loosen up so they just turn freely. You'll be good to go. assuming the shoes and drum surface are in good working order.
If its all shot look at rear discs but get some with the biggest parking brake you can find.
Go back only to the 60's Drum brakes overheated on any decent grade, then splash thru a puddle getting one btake wet and the next brake application slews you into another lane. Simply getting them adjusted so the car would stop in a stright line was difficult at best and sometimes it could not be done at all.
Chrysler came out with "center-plane" Drum brakes that were fantastic! The trouble was even with the complex adjusting rig needed to properly adjust the things the adjustment never lasted over a few miles.
In Europe, AlFin made the biggest, baddest alloy drums ever seen and they failed to cut the mustard. In 1956 Jaguar showed up at Le Mans and blew everyone into the weeds with Disc brakes and no one ever looked back. End of story.
Except for Jeeps hanging on the side of a hill. There its nice to have drums on the rear to ease back down as most rear disc setups have a rather small parking drum.
Freakaccident has it right. Maunally adjust the rear drums to get them to work properly. The built in adjusters leave a lot tp be desired.
The single piston caliper on Jeep front ends tends to **** in the bore and jam there when panic braking and 12 feet pressing down on them won;t even slow the damn thing down. This is personel experence talking here. I now have 11" slotted rotors and 2 pot, twice as big as stock, calipers on the front of my XJ. Thats where to spend your money. On the rear adjust the drumsso tight you can't move the tire at all then loosen up so they just turn freely. You'll be good to go. assuming the shoes and drum surface are in good working order.
If its all shot look at rear discs but get some with the biggest parking brake you can find.
my age is not of an issue here... my information about the drum brakes working too well is coming from profesional mechanics and car enthusiasts from muscle and offroad backgrounds and from a member of a company that manufactures breaks...
the drum brake does infact work too well.... why do you think drum breaks lock up??? and stay locked at times.???? the basic idea behind a brake is to either force a bad outward (drums) or force a pad inward (disc) and when your drum brake is forcing pads outward they connect at about 90%+ of the inside of the drums surface.... and with the disc brake pad they connect with about 40% of the disc.....
now if you simply think about it..... Drum Brakes Have More Surface Connection Than Discs Do
so there for they can create more drag than disc brakes do
and like other people on here, i'm not favoring drums, i favor discs simply like i said before, they're much easier to maintaine...
my point behind all of this was again that Drum brakes can/and do infact work too well.. case and point
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Year: 1990
Model: Cherokee
Engine: 4.0L`
[quote=That Jeep Guy XJMJ;212136]my age is not of an issue here... my information about the drum brakes working too well is coming from profesional mechanics and car enthusiasts from muscle and offroad backgrounds and from a member of a company that manufactures breaks...
the drum brake does infact work too well.... why do you think drum breaks lock up??? and stay locked at times.???? the basic idea behind a brake is to either force a bad outward (drums) or force a pad inward (disc) and when your drum brake is forcing pads outward they connect at about 90%+ of the inside of the drums surface.... and with the disc brake pad they connect with about 40% of the disc.....
now if you simply think about it..... Drum Brakes Have More Surface Connection Than Discs Do
so there for they can create more drag than disc brakes do
and like other people on here, i'm not favoring drums, i favor discs simply like i said before, they're much easier to maintaine...
my point behind all of this was again that Drum brakes can/and do infact work too well.. case and point[/quote
Sorry about the age comment. I failed to flesh that out. I tend to think in shorthand and my typing can't keep up.
What I was thinking was have you driven all drum braked cars back in the day? They were terrable! In addition to not stopping, overheating and fadeing the cars would weave back and forth inducing a great deal of instability. Get a drop of water in the drum and the car pulled to one side or the other. The advent of disc brakes eliminated just about every vice the drums had. Even today with disc/drum systems if you break hard from speed the rear drums will cause the back to wiggle waggle back and forth.
The thought that drum brakes worked too well had to be taken out of context. What they did was have one leading shoe and one trailing shoe. The leading shoe actualy increased brake pressure via mechancil leverage due to where rhe shoe pivited from. Conversely the trailing shoe did very little work leading to the pair of shoes wearing unevenlly causing the leading shoe on either front wheel to grab unevenly causing the car to pull to one side or the other in yet another way causung instability under braking.
I raced Corvettes with drum brakes in the 60's and everyone was weaving around under braking. When the all disc Corvettes arrived it was a new day!
Getting back to the thread one could drill the backing plates to vent excess heat. Drilling the drums themselves could be dangerous.
Finally, the leading/trailing shoe thing is an advantage to Jeepers because when reversing back down a hill the trailing shoe becomes the leading shoe and adds the mechancial leverage increasing braking force in reverse. Something a rear disc cannot do for you.
I hope that seems a little clearer. RB
the drum brake does infact work too well.... why do you think drum breaks lock up??? and stay locked at times.???? the basic idea behind a brake is to either force a bad outward (drums) or force a pad inward (disc) and when your drum brake is forcing pads outward they connect at about 90%+ of the inside of the drums surface.... and with the disc brake pad they connect with about 40% of the disc.....
now if you simply think about it..... Drum Brakes Have More Surface Connection Than Discs Do
so there for they can create more drag than disc brakes do
and like other people on here, i'm not favoring drums, i favor discs simply like i said before, they're much easier to maintaine...
my point behind all of this was again that Drum brakes can/and do infact work too well.. case and point[/quote
Sorry about the age comment. I failed to flesh that out. I tend to think in shorthand and my typing can't keep up.
What I was thinking was have you driven all drum braked cars back in the day? They were terrable! In addition to not stopping, overheating and fadeing the cars would weave back and forth inducing a great deal of instability. Get a drop of water in the drum and the car pulled to one side or the other. The advent of disc brakes eliminated just about every vice the drums had. Even today with disc/drum systems if you break hard from speed the rear drums will cause the back to wiggle waggle back and forth.
The thought that drum brakes worked too well had to be taken out of context. What they did was have one leading shoe and one trailing shoe. The leading shoe actualy increased brake pressure via mechancil leverage due to where rhe shoe pivited from. Conversely the trailing shoe did very little work leading to the pair of shoes wearing unevenlly causing the leading shoe on either front wheel to grab unevenly causing the car to pull to one side or the other in yet another way causung instability under braking.
I raced Corvettes with drum brakes in the 60's and everyone was weaving around under braking. When the all disc Corvettes arrived it was a new day!
Getting back to the thread one could drill the backing plates to vent excess heat. Drilling the drums themselves could be dangerous.
Finally, the leading/trailing shoe thing is an advantage to Jeepers because when reversing back down a hill the trailing shoe becomes the leading shoe and adds the mechancial leverage increasing braking force in reverse. Something a rear disc cannot do for you.
I hope that seems a little clearer. RB
Last edited by RedBaron; Jun 21, 2009 at 03:03 AM. Reason: dropped a key thought
CF Veteran
Joined: Nov 2008
Posts: 2,473
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From: Paso Robles Ca
Year: 1991
Model: Cherokee
Engine: 4.0
I had 11" drums on my old ****** and it would stop on a dime
unless I went through any water then just like all drums they stopped working
until they dried out
unless I went through any water then just like all drums they stopped working
until they dried out
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Joined: Sep 2009
Posts: 35
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Year: 1988
Model: Cherokee
Engine: Inline 6 4.0
so essentially,
to save ur *** from a downhill in either direction while offroading,
disc is good if ur going mudding.
drum is better for road speed?
thats what i got from reading the thread
to save ur *** from a downhill in either direction while offroading,
disc is good if ur going mudding.
drum is better for road speed?
thats what i got from reading the thread
CF Veteran
Joined: Oct 2007
Posts: 3,883
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From: W-PA
Year: 2001
Model: Cherokee
Engine: 4.0
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