| Author |
Message |
    
Olaf Kilthau (Olaf)
| | Posted on Saturday, December 14, 2002 - 12:18 pm: | 
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I'm thinking about changing my rotors to the DBA rotors but I don't know whether they will really help brake better. They're not a larger rotor, they only dissipate heat better, but I don't generate the same heat in Disco as I would in a race application. Any
opinions? |
shawn peterson
| | Posted on Saturday, December 14, 2002 - 07:33 pm: |
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I have them on my 96 D1, they work great, especially when the truck is loaded down. Purchased from rover connection, FYI they reccomend using the stock pads, not performance or kevlar, not sure why. |
Gabriel Guay (Gearhead)
| | Posted on Saturday, December 14, 2002 - 11:01 pm: |
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I'm one of those guys who read D-web alot but seldom post. However, I used to run a speed shop and build motors in my past life. I agree with Olaf, I don't see these trucks going fast enough to need vented rotors. I have owned many cars and trucks over the years, all of them but the rover needed rotors by 35 to 40K miles. ( all were hard driven but well maintained ) My first Rover, 99 D1 still has the original solid rotors that came on it when I bought it in 99. I have repalced the pads with stock LR pads at 50K miles and I am now at 92K miles. The breaks always performed very well and they never pulsed. Granted I am due for a set of rotors and pads. I will replace the rotors with the same LR solid rotors and expect to get another 92 to 95K miles out of those.
Gabe |
RJ Clayton (Tozovr)
| | Posted on Sunday, December 15, 2002 - 12:05 am: |
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Drilled rotors WILL crack and craze around the holes. Period. Slots dissapate the gasses that get built up Very well...no need to drill them out, as you'll only reduce the mass of the rotor (more warp prone). |
nadim
| | Posted on Sunday, December 15, 2002 - 11:06 am: |
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My brother (BMW fanatic and Rallye experienced driver) said that the ONLY advantage of slotted, vented, or cross-drilled brakes were to dissipate heat better than solid ones, in order to LAST more, and not crack.
The ideal for more stopping power is said to be in bigger disks, therefore, if we can fit a larger diameter solid disk, that would be ideal (there is an article backing that up in Dec. issue of 4 Wheeler, or Patterson's 4 Wheel Drive & Offroad)
That is all I can say, although, then, why would Porsche, Ferrari, MB...bla bla bla...be using them? |
Will Roeder (Will_Roeder)
| | Posted on Sunday, December 15, 2002 - 12:35 pm: |
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Yea, you wont notice a hige difference in normal everyday driving. The main advantage to these rotors is that they will dissipate heat quicker, thus reducing brake fade. |
Russian Landy
| | Posted on Sunday, December 15, 2002 - 01:11 pm: |
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Why bother? The stock brakes are excellent and quite capable of hauling the Disco-Pig right down from its pathetic top speed even when heavily loaded, without fading. You'll just waste money better put into the piggy bank towards a new winch, and shorten the lives of the rotors (they WILL warp more easily with mass taken out).
A Disco is NOT a BMW or a Porsche. A BMW or Porsche driven hard generates a huge amount of heat in the brakes from repeated hard acceleration and hard deceleration setting up for turns. For that kind of use you need all the heat disappation you can get, and slotted rotors can be a good thing. You simply can't drive a Disco-Pig like that, and so you don't need to screw with the big rotors. |
Will Roeder (Will_Roeder)
| | Posted on Sunday, December 15, 2002 - 02:01 pm: |
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Russian Landy,
No one ever said that a Land Rover was a Porsche or BMW. However, the Disco's stock brakes are not that great, especially once you add hundreds or even thousands of pounds of gear, lift the truck several inches, and add larger tires. Sure, the stock brakes are fine for a stock truck, but IMHO not for a heavy, lifted, truck with tall tires.
Also, noone ever said about changing the size of the rotor. No modifications are required to fit the DBA rotors and pads. Plus, they really dont cost THAT much more than new genuine parts. |
RJ Clayton (Tozovr)
| | Posted on Sunday, December 15, 2002 - 06:09 pm: |
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Quote:My brother (BMW fanatic and Rallye experienced driver) said that the ONLY advantage of slotted, vented, or cross-drilled brakes were to dissipate heat better than solid ones, in order to LAST more, and not crack.
The ideal for more stopping power is said to be in bigger disks, therefore, if we can fit a larger diameter solid disk, that would be ideal (there is an article backing that up in Dec. issue of 4 Wheeler, or Patterson's 4 Wheel Drive & Offroad)
That is all I can say, although, then, why would Porsche, Ferrari, MB...bla bla bla...be using them?
Almost every modern rig (Geo to G-wagen) has Vented rotors. Look at Porsche's Race Cars...though the cars on the dealer lot do have cross drilled rotors, the factory {race} cars DO NOT. Hit some SCCA sites or stop by a race or two...ask why they don't run drilled rotors...then see my earlier post.
Cheers!
RJ |
Rich Lee
| | Posted on Sunday, December 15, 2002 - 09:54 pm: |
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Hi All,
I have a set of the DBA front slotted (not drilled) rotors on my D1. I bought them from DAP and they were less expensive than OEMs or some of the aftermarket ones. They work very well with the OEM pads. They did not work well with the kevlar pads (read my earlier post in D2 brake pad life expectancy on that). With the Kevlar pads they "chirped" annoyingly under braking and the pads did not last long. Perhaps this is because the slots worked against the Kevlar pads like Cuisinart blades.
I am very leery of non-OEM crossdrilled rotors. I have seen several versions (especially home-drilled) crack around the holes, even those with chamfered holes. I suspect this is due to either the wrong metal being used, or the lack of stress-relieving after drilling. There are some places that make incredible claims on rotor wear and durability by dipping them in liquid nitrogen. Any thoughts on that? |
Gabriel Guay (Gearhead)
| | Posted on Sunday, December 15, 2002 - 10:33 pm: |
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There is a difference between slotted, and ventilated rotors.
Slotted rotors are meant to give the gas a place to escape when the brake shoe material vaporizes. Disco�s don�t generate the high speeds that cause this phenomenon to happen. It requires very high RPM's of the rotor and sharp very hard braking. That�s one of the causes of brake fade along with heat at the rotors and pads to start heating the brake fluid. The kind of brake over heating a disco will see is generated from the pads braking for long periods of time like on a long grade descent. This kind of brake fade is mostly due to glazing. Slots will help shave the glaze but will also wear the pads much faster than without.
Ventilated rotors are really marketing hype from the sixties as an added benefit to making a hollow two sided thin rotor to save unsprung weight. The lighter rotors mean a lighter wheel and tire combination which translates to less stiff shocks needed to keep the wheels on the ground at speed on bumpy roads. The softer shock makes the ride less harsh. The added by product of this design was that air would pass though the cavity and help cool the rotor. This is only really affective if the air can be directed to the inside of the hub ( like Stock cars & Indy cars do ) where the cool air would then flow from the hub through the rotor vanes and out the edges ( this requires a very open wheel design ). The lighter ventilated rotors also tend to heat up faster as well as cool down faster. That�s why all modern cars need the rotors turned to shave away the uneven thickness of the rotor after you have just heated them up real good on a panic stop at highway speeds or hit a deep puddle just after hard braking.
When I ran the speed shop, I sold countless slotted cross drilled rotors to customers with Camaro's, Mustangs and such only to sell them plain factory type rotors later because the brake pads and rotors just don�t last in a street application. I would modify ventilated rotors for the SCCA customers by shaving them down to reduce weight and slotting to improve venting gasses. The wear and tear on a race car is great and these cars get rebuilt on a regular bases.
That�s what I know about brakes from my experience in the business from about 15 years ago. I don�t think metallurgy has changed that much in the past 15 years and out side from the boys at Lemans, Carbon Fiber brake rotors aren�t available yet.
I still believe a solid rotor will wear the longest with out warping and heat up the slowest. The extra diameter of our tires and the tire type itself is so heavy, a lighter rotor would not make much difference. The added mechanical advantage of the larger diameter acting on the breaks and inertia is what you are feeling.
My 87 F150 truck weighed more than the disco, Had smaller disc in front and drums in the rear and needed new rotors every 30K
Many times poor brake booster vacuum due leaky vacuum hoses is misinterpreted for weak brakes
Not saying Ventilated isn�t better or worse just that it wont affect braking power and more likely to warp in an off road application like a steep decent just before a water crossing.
Slots will slightly improve braking at speed and wear the pads much faster.
Larger rotors is where I would go if you really want to improve the braking power.
Sorry for the long ass post, I had the day off today.
Just my opinion.
Gabe |
M. K. Watson (Lrover94)
| | Posted on Sunday, December 15, 2002 - 10:40 pm: |
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gabe,
just one question, what produces these gases that need to be removed, speed or heat, if it is indeed speed forget about what i am about to ask but if it is heat then what is the difference between a light car going fast and braking hard at the markers or a heavy laden truck going much slower?
mike w |
Gabriel Guay (Gearhead)
| | Posted on Sunday, December 15, 2002 - 11:13 pm: |
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Both create gasses but Speed creates very high heat on the surface of the rotors and pads before the rest of the pad heats up. This causes a thin layer of brake pad material to vaporize almost instantly. Slow hard braking heats up the rotor but shaves off brake pad material as dust and doesn�t create significant gas build up right away because the rotor is cooler than the pads unless holding the brakes hard for a long time.
It's kind of like the differance between buffing out a scratch in your paint with polishing paste by hand versus a power buffer. If the buffer is too fast, the top layer of paint can get too hot and burn the finish.
Again just my opinion.
No real scientific tests to support my opinions.
Even today�s heavy trucks are now using the lighter ventilated rotor design but have really large diameter rotors. Much larger than was the norm 15 years ago.
Gabe |
Olaf Kilthau (Olaf)
| | Posted on Sunday, December 15, 2002 - 11:22 pm: |
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Thank you for your opinions! I guess I'm going to stick with the OEM rotors unless anyone knows of a way or kit to fit larger rotors and Pads? |
Todd Phenneger (Toddp)
| | Posted on Monday, December 16, 2002 - 02:34 am: |
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Wow!
I had over a page of reply and when I sent it it got lost. Damn.
Oh well, I dont have the energy to re-type it all. BUT...I'll summarize.
We are talking BRAKES People, dont cheap out.
A few points to remember.
1) Our vehicles weigh 4,500lbs
2) We have decent sized rotors at 12" and GREAT AP 4-pot calipers with massive piston bores driven by a gigantic booster. So we have clamping force.
3) our rotors are SOLID....there is a reason most vehicles and many much lighter and smaller AND all new Rovers, RRC, D2, etc all have vented Rotors. Safety.
4) We can convert to Vented Rotors. BTDT about a month ago. Got almost everything from Bill at Great Basin Rovers. DBA Gold Rotors (vented, slotted, drilled) with the Bendix pads that DBA recommends (kevlar/aluminum matrix).
5) If you cant go vented, at least upgrade something.
6) Slots and drilled holes are not a joke if done right, unfortunately often they are. If your doubt the holes, at least get the slots. They outgass the gasses that build up between pad and rotor to reduce brake fade, they increase bite on the pad and almost always will reduce brakeing distances a small amound everything else being equal. Properly slotted pads should NOT reduce brake pad wear. Many companies dont properly chamfer the edges.
7) Check out DBA rotors, they use high quality base stock metal, they drill the holes proplerly before final machining of the rotor. This reduces stress fractures. The slots and holes are chamfered.
8) If you doubt me do some serious research, dont listen to rumors. I work with a company that specializes in brake upgrades. They always improve a cars performance. Even when an old Volvo 242 came in needing brakes and the shop accress the way had put on 3-different sets of pads, 2 different sets of rotos. Well, One try and she had a 242 that stopped better than she ever dreamed.
9) If your tired of me ranting, stop reading. :-)
10) I'm Biassed, and stubborn.
11) I have DBA vented/slotted/drilled rotors on my car. I dont think the drilling is necessary but at Bills behest I tried them. I'm very happy, my Rover stops WAY better than stock (I've driven quite a few) Stops better than many Stock AUdi's (Driven quite a few), and from WAY to FAst stops progressively and I can balance on the edge of lockup (with ABS defeated) or totally smoke the tires at 80mph. The Bendix pads work great when hot or cold. Trust DBA on them. Great pads. Quiet, no squeal, $69pr. I have the Porterfield pads that AB sells on my track car, they work great when HOT, not when cold. But try the Bendix.
12) Bottom line....when your driving with your kids in back, roof rack full, maybe a trailer behind you and turning Big heavy tires and now weigh 5,500+ lbs, going down a Mt. Pass, using you brakes often to slow down for those 40mph curves, and then on a straight at 70mph a deer jumps out in front....Do you want your brakes to fade??? I sure as hell dont. Its not worth it to me. You dont need the holes, but at least get good pads, quality slotted rotors, and if you have an extra $150 upgrade to vented rotors as well. My brakes Stock I could induce fade on some favorite roads. I cant induce fade now. Time for larger tires and more power. :-)
You may disagree but thats my opinion. I'll be happy to explain more to anyone that wants it.
Todd P. |
Todd Phenneger (Toddp)
| | Posted on Tuesday, December 17, 2002 - 02:28 pm: |
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Wow,
I never realized my comments would stop this thread in its path. :-) I hope I didn't scare everyone away.
Happy braking
Todd |
GregH
| | Posted on Tuesday, December 17, 2002 - 03:24 pm: |
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hehe-I'm on your side Todd.
I plan on upgrading to stock axially-ventilated rotors in my '89 RRC when I can afford it. Just debating the spacer in the caliper question for me. I still am nervous about leaks at the spacers.
I've never tried the Kevlar/Aluminum pads either-how expensive? (I'm a CB).
AS far as cross-drilled rotors Porsche DOES use them on factory racing vehicles and they are STOCK on many new Porsches including new 911 Turbo. (although new ceramic rotors are not I believe). Cross-drilling must be in correct pattern for rotor with chamfering and proper stress relieving and then there should'nt be problem with cracks-I've used them for years with NO cracks.
GregH |
GregH
| | Posted on Tuesday, December 17, 2002 - 03:43 pm: |
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BTW-to clarify the holes in stock Porsche rotors are not actually cross-drilled but are cast into the rotor. Aftermarket rotors are drilled. |
Todd Phenneger (Toddp)
| | Posted on Tuesday, December 17, 2002 - 04:35 pm: |
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Greg,
My understanding is that they are not actually cast in the rotor, but that a rotor blank is cast, the holes are drilled, then the rotor is machined. I believe they drill while hot and stress relieve them afterwards. I have heard both though so I'm still not sure.
We used Ceramic Rotors on the 4ktq RaceCar and they were great except for two problems.
1) Almost undrivable on the street because when cold the pedal effort to keep from rolling down a hill took both feet.
2) AT the end of the long straight the rotors wold cool down SO much that initial bite was horrible as they were not warm enough to work. We were hitting about 140+ at the end of the straight. I guess the extra 10mph that the Porsche GT-3's were getting was enough as they didn't seem to have that problem. We are back to stock porsche rotors and Pagid Pads and are very happy with them.
As for the Caliper Spacers, I used them and have had no leaks. The seal is very simple that rover uses and as long as your mating surface is clean you should be fine. The company I got mine from didn't include torque specs so I consulted a Torque Table and tightened to 55lb ft if memory serves. So far no problems. Only 0 fade and great braking. :-)
The Bendix pads were $69 from Bill at GreatBasin Rovers. I'm very happy with them. They handle everything well. exactly what I look for in a street pad. NOt sure what wear is like yet but so far I believe I'll buy another set when I have to.
l8r
Todd |
Gabriel Guay (Gearhead)
| | Posted on Tuesday, December 17, 2002 - 10:08 pm: |
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Todd,
You didn't stop it in it's stracks man. It's just some of us have other things to do, like earn a living.
I still think you guys are buying into the hype.
We are not talking 140 Mpr road rockets here, or possibly it's only my rover that's slow, and has enough drag to coast to a stop from free way speed faster than the stopping distance of a Jeta, but hey, thats just my opinion.
Dude, if slots and holes make you happy, it can't be that bad.
Well, back to salt mines I go. |
shawn peterosn
| | Posted on Tuesday, December 17, 2002 - 11:47 pm: |
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checking back in, I have the DBA rotors with oem pads, they work better than the stock setup did, I see a lot of posts saying they (crossdrilled and or vented rotors)warp and crack, does anyone have these rotors on their disco that have warped or cracked? has anyone puts these on their disco and noticed a drop in braking performance? anyone?
Now if your chosing between upgrading brakes and lets say OME springs, it's probably not the #1 choice but if you need to replace rotors anyway why not spend a couple extra bucks in parts and go for it. Just a thought
Shawn |
GregH
| | Posted on Wednesday, December 18, 2002 - 12:42 am: |
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Todd-thanks for info. I like Pagid pads too and used to use the Pagid Orange pads on the track and switched to some Ferodo organics on the street on my 914-6.
Yeah, everyone used the term "cross-drilled" but a PCNA tech told me about the cast holes at a POC meet. Since Porsche sources rotors from Brembo, Ate, and Zimmermann who knows what the truth is.
I think I'll go for the spacers when the time comes but I'll try the stock later model vented rotors before I decide if I really need cross-drilled/slotted.
GregH |
GregH
| | Posted on Wednesday, December 18, 2002 - 12:48 am: |
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Todd-BTW do you work for Stoptech?
Just curious... |
mike
| | Posted on Wednesday, December 18, 2002 - 06:48 pm: |
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what's dba |
Will Roeder (Will_Roeder)
| | Posted on Wednesday, December 18, 2002 - 06:54 pm: |
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Disc Brakes Australia
http://expeditionexchange.com/dba/ |
Todd Phenneger (Toddp)
| | Posted on Thursday, December 19, 2002 - 04:18 am: |
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Greg,
Funny you should mention Stoptech. I dont work for them but my Best Friend / Ex-Roommate owns an AUdi/VW tuning shop.
www.achtuning.com
that deals with Stoptech exclusively for their "serious" brake upgrades. I have nothing but good things to say about them. That company disigns every brakings system to match the car. Their flaglship S4 with over 400hp has 14' rotors in front and 13" rotors in back. The rear calipers are almost as large as the fronts (massive) and contrary to what I though, there are not bias issues and it DID make a difference over just doing the fronts.
I someday may put Stoptechs on the rover but for now my DBA setup is keeping me very happy.
And if (gearhead) wants to believe I'm believing the Hype he should run some tests himself.
No knocks on you Gabriel, There is a LOT of hype out there, but there are legitimate brake upgrades that work also. I dont know your exact experiences but a lot of changes have happened in the last few years.
I dont think our Disco's need swiss cheesed rotors, but there are no disadvantages to slotted rotors, they dont crack, dont wear pads out fast, and if anything they just ensure a safer vehicle. DBA rotors are about $89 - 99 each. Same price as rotors from AB or others, so you may as well just get them and be done with it.
Greg, I'm jealous of your 914-6. I want one.
l8r
Todd |
GregH
| | Posted on Thursday, December 19, 2002 - 12:21 pm: |
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Yeah, I want Stoptech's system on my '01 S4 but I can't justify the $. Thought if you worked for them you might know how to get for less than retail (HAHA)!
BTW-don't be jealous of the 914-6, my wife is currently using it for a storage table in my garage (ouch!) I need to do a major tear down on it.
I can only afford so many toys and right now the RRC is getting my attention and $. 
GregH |
Gabriel Guay (Gearhead)
| | Posted on Friday, December 20, 2002 - 12:12 am: |
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Todd, I�m not disputing that a brake upgrade make a difference on a high performance road cars, I just don�t believe in Cross drilled rotors, and I don�t think grooved rotors hurt anything. I just don�t think the impact of grooved rotors are that great that it would be worth changing rotors for. The issue I have is more with the ventilated rotors that are meant for road cars. I personally like solid rotors for a off road application over the ventilated rotors. Even though my truck was built in 99, it still is a truck meant to perform well off road with 70s technology and just happens to have plush leather seats and civilized interior. This thing wasn�t meant to hang with the Audi�s and Saabs on the autobahn. Granted I do see 75 Mph from time to time on 440 in NC and the brakes are my least worry. I worry more about not making any sudden maneuvers at 75 mph with 100� wheelbase and high cog. This truck wasn�t designed for that. Now the Mini cooper S is a little more suited to that but, now I worry about getting run over by people like me in those Rovers with bad brakes! I like knowing my solid rotors won�t warp when I submerge them in ice cold water after a long decent in the mountains when in Canada. I had a Ford that would get terrible wobble in the front end after some deep muddy water crossings because the rotors would get clogged up with debris and hot spot causing warping. I can�t imagine driving Disco hard enough to induce brake fade. But then again, Being from Canada and learning to drive on packed snow most of the year, I tend to be rather easy on brakes. I don�t think switching to slotted vented rotors will hurt anyone�s on street performance but may not be the best set-up for deep woods off road application. I also don�t agree with Land Rover that the rotors must me changed out at 30K with the pads. Like I said in my original post, I�m at 92K and the rotors are still within spec on second set of pads.
But like I said before, If groves and vents make you happy, go for dude.
Ill stay with what has worked well for the last 92K
By the way, I�m jealous of the 914 too.
Gabe |
Todd Phenneger (Toddp)
| | Posted on Saturday, December 21, 2002 - 11:18 am: |
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THanks for clarifying Gabe,
For offroad, I agree, a simple solid rotor works well and has nothing to get clogged up in there. For me though, I spend so much time on-road and on the Interstate doing 75mph that I wanted to know I have the best brakes I could find for the money. And I think I've done that. Its just peace of mind, I travel a lot of mountains and tow a a boat around a lot as well. Not something I"d do for the sake up upgrading a working package, but if your already replacing rotors and pads, (I had to, at 110k miles my pads were gone and my Rotors were warped BADLY). Then you might as well spend an extra few bucks to upgrade.
Anyhow, I think we've beaten this thread almost to a pulp. :-)
Greg' - I have an AUdi 4000turbo quattro in the garage that is also a table right now. Its almost done though. All new Sound Insulation inside, wiring upgrades and tidying, ur-quattro suspension. Just needs Paint and it will be For Sale so I can buy an engine for the Race Car. :-)
l8r
Todd |
Olaf Kilthau (Olaf)
| | Posted on Sunday, December 22, 2002 - 06:58 am: |
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Hello everyone! Thanks again for all of the participation on the question I initiated several days ago. I spoke with a euro service guy who also builds BMWs of all model years for racing. The major point was that the rotor to use depends on the vehicle and it's application. He said that he would not use a slotted and drilled rotor on our Rovers but he would rather use one or the other. He also said that the slotted rotors generally give better braking but will wear out the pads much faster, especially on our heavier vehicles. His compromise would be to use the drilled rotors with either the OEM pad(limit squeaking) or a metallic pad(carbon combination ie. Ferrodo) which would give us slightly better braking, but that the main benefit would be esthetics! He also discouraged Kevlar rotors because they would squeak too much. I went on Ebay and purchased a set of Brembo rotors for $167 plus $25 shipping from Terry Chan - terrshop.com out of Canada. It also seems that Rover Connection sells the DBA rotors for $75 each, if some of you are considering making the change. For you fellow Porschephiles, this guy liked Zimmerman better than Brembo for our Porsches. |
Olaf Kilthau (Olaf)
| | Posted on Sunday, December 22, 2002 - 07:01 am: |
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I meant "...discouraged Kevlar pads..." not "rotors" on the previous posting. |
curquieta
| | Posted on Monday, December 23, 2002 - 11:34 am: |
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Drilled/Slotted Brakes. The holes catch mud and debris which in turn munches the pads. |
GregH
| | Posted on Monday, December 23, 2002 - 11:03 pm: |
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Todd-Just read about achtuning in european car. Your friend's red S4 with RS4 upgrades is very nice-I'm jealous. Maybe if I could upgrade my S4 with Stoptech systems and be able to write off cost as business expense I would go for it!! haha
GregH |
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