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PostPosted: Wed Apr 12, 2017 2:57 pm 
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Joined: Fri Sep 23, 2011 2:10 pm
Posts: 369
Location: Tolland, CT
Hi all. Looking for some insight on options to convert the original
drums to discs. Using 15" wheels but want to keep the 4 bolt pattern
to avoid having to replace wheels that I like.

What's involved ........ are there direct fit kits?
Jack

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John D .... original 240 past, 260v8Roadster current


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PostPosted: Sun Apr 30, 2017 3:19 pm 
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Location: Tolland, CT
Really guys! 26 views and not a single reply. I can't believe it, not on this site.
Anyway, I'm moving forward on my own, rear discs keeping the 4 bolt 15" wheels
and new bearings, repack if they look gook. Can't remember if I did them when I
bought the car. 1st thing I did was brakes.

I'll get back on when done.
Jack

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John D .... original 240 past, 260v8Roadster current


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PostPosted: Sun Apr 30, 2017 3:32 pm 
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Location: CT
Hey Jack ` it's a popular swap and the hardware is made by several companies. The only advantage discs have over drums is non-fading during hard use or when wet. Drums always "bite" better at traffic speeds so they can save you from a rear-end collision in traffic, but if you're driving the proper 3 second interval behind the next vehicle that isn't a problem.

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PostPosted: Sun Apr 30, 2017 9:08 pm 
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Location: Tolland, CT
Thanks for the thoughts Frank. This happens to be a rare time I'm not fully in agreement, however. A proper set of discs will out brake a typical drum set up in both situations. Vented discs all around, drilled or slotted (best in the wet especially if cooling ducts feed the brakes in front), have totally changed
the typical stopping distances of modern vehicles. Granted, much has to do with size, brake swept area
per ton. I've followed stopping distances 60-0 and 80-0 for many years. Look at high performance cars like the 911 back in the 70's and the early Z's and you'll see braking was not a strong point.
fixed or sliding calipers and piston # (clamping pressure) also contributes.
Anyway, I'll let you know when done.

Are you going wed. nite? If weather is decent I'll drive the roadster to Hamden and go over after work.
Hope to see you there.
Jack

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PostPosted: Mon May 01, 2017 7:29 am 
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Location: rhode island
It goes from a basic set up to Wildwood Brakes, so depends on what you want. The adapters are the most expensive part. I have the ones that use the Maxima Calipers. Not sure if it's the same bracket, then there is the 240sx brakes. Then 280zx rotors, I'm using crossed drilled slotted rotors so that adds to the price, with steel brake lines. If you have good backing shields you should save them, or people cut them off. To save them, well now you might as well do your wheel bearings. Easy way out is cut. Then you have to increase master cylinder size. Booster helps as well. I have a 280 booster, then I'm using a 300zx 1" master cylinder. Or could use the smaller 15/16th 280zx master. The system requires no proportioning valves, so take those out. Some systems might, so get an adjustable one. http://www.silverminemotors.com/


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PostPosted: Sun May 07, 2017 9:24 am 
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Location: CT
Disc brakes have been around since the turn of the 20th century, but only in wide use for about 70yrs. When horse drawn carriages first became motorized "trucks", the old "band" style external wheel brakes were no longer adequate to stop the faster and heavier wagons, so the drum brake offered far better braking. The railroads all used drum brakes for years. Drums provided good braking, but overheated when dragged over long distances (like stopping a train), lost bite when they got wet and were a huge pain to keep adjusted all the time. Replacement required lifting the train car off the track to pull the steel wheels one at a time at the roundhouse. Girling and Westinghouse began making disc brakes for trains, which were far lighter, shed water quickly and were a breeze to change right in the rail yard; any brakeman could change a railcar's brakes by himself. They didn't stop the train better than drums, but they saved maintenance time and weight and were far less expensive than drums.

With the advent of aircraft the lightweight discs saved weight and resisted fading on landing and recovered from being wet more quickly than drums did. WWII advanced the disc technology and discs became almost standard on most (not all) US warplanes, where their slightly substandard braking power didn't matter much ~ they had the whole runway to stop on. Again, weight, expense, and easier maintenance outweighed the stopping advantages of the better-braking drums.

After the war discs slowly transitioned over to cars. By the mid-1950s the Citroen DS, Renault, Jaguar, and some Mercedes cars were pioneering disc/drum combinations. The Studebaker Avanti became the first car in the USA to use discs and drums in 1962. Discs offered high-speed resistance to fade, lighter weight, lower cost and easier service, altho they didn't stop cars as well as a good, dry set of drums did. Drums remained in use in the USA up until the mid-1980s.

Your studies on stopping distances over the past 50yrs will show lower numbers, but those are hugely influenced by the VAST improvement in rubber compounds, dedicated thread design and radial construction of tires over a half-century, the introduction of proportioning valves, progressive power brake boosters, better balanced cars, Anti-Lock Braking Systems (ABS) and FAR lighter weight of today's "plastic" cars. True, the cars are stopping quicker, but that's not due expressly to the use of discs.

You can't beat physics no matter how hard you try. Drums have many times more swept area than discs do, offer far better 'bite' (especially at slower speeds), and are used almost exclusively for handbrakes because the disc holds so poorly. All things (tires, weight, car balance, brake boost technology) being equal, a dry set of new drums will out-stop a dry set of new discs everyday, until the drums get wet or overheat and begin to fade.

The 4-wheel disc swap is very popular and I doubt you will ever regret it, but you will notice the difference the very fist time you stomp on the brake pedal in slow traffic.

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PostPosted: Tue May 09, 2017 3:01 pm 
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Location: Tolland, CT
I thought my reply would spark a more detailed response, Frank.
Couldn't let you get away with 2 sentences.

BTW, I'm in agreement on many of your points. You can see there are a huge no.
of variables. You can look at light cars like VW's that show 80-0 in 300' and heavy
car in the 4k area doing 215-220'.

Solid discs vs drilled/slotted have very different wet performance characteristics typically.
Drilled rotors have a greater tendency to warp, especially if not torqued correctly. Etc. etc.

I'll let you all know how it goes post the transdisconal.

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PostPosted: Tue May 09, 2017 6:15 pm 
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Location: CT
:lol: Haha! OK Jack, you got me. You know what buttons to push.

I ask that you bear in mind that Datsun was trying very hard to make the cheapest good-performing car they could produce, and discs cost and weigh less than drums. They used the disc/drum combination to afford the car good high-speed fade resistance and good low-speed bite. If discs had been the equal of drums, Datsun would have jumped on the chance to save some production money and overall weight by making them 4-wheel disc cars.
There was a sound reason why they spent more for the heavier drums.

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PostPosted: Fri May 19, 2017 4:37 am 
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Location: rhode island
Ok, so why don't Ferraris', Lamborghini's, Bugatti's, Formula 1, etc use drum brakes. :? :? :? :? :? :shock: :roll:


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PostPosted: Fri May 19, 2017 8:50 am 
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Location: CT
Good question, Paul.

Cars which spend much of their time at sustained high speeds (race cars, actual sports/GT racers, Formula cars) have little need for the extra low-speed grab a good double-leading shoe drum brake offers. Instead they benefit from saving weight and avoiding fade, at which the disc excels. They simply don't spend enough time at street traffic speeds to take advantage of the better bite of drums, which excel at lower speeds.

But that doesn't say they abandoned drums completely. Ferrari used drums clear up into the 1960s on some street models and offered them as buyer option until the 90s. Maserati was the final exotic marque to switch to the cheaper, lighter 4-wheel discs, and they could still be ordered as an option well after that. The entire Z line retained the excellent Disc/Drum combination (best of both worlds) up until the 300ZX spaceship cars.

Cars which spend most of their lives at low speeds in traffic still depend on drums. The USPS used 4-wheel drums on all their mail jeeps until just very recently. Most firetrucks still use drums because they spend most of their time at low street speeds and needing to slow all that weight for corners. School buses still use drums. Most heavy hauler dump trucks still use drums so they don't smush traffic ahead of them in low speed stops. My town's trash trucks use 10-wheel drums.

But drum brake fade has resulted in several fatal dump truck crashes in CT over the past 20yrs or so, notably on long hills (twice on Avon mountain), and a winter holiday fire truck crash which killed some firefighters in the mid-1980s. But discs simply won't stop high weight loads quickly (trucks down hills, trains on tracks, Heavy vehicles in slow traffic, etc). Since Jack began this thread, I saw a modern (new) Ford sedan fleet vehicle with rear drums, so they are still being used for some common street applications.

Bottom line is, the greater swept area of drums out-brakes discs as long as the drums are dry and in perfect shape. Drum brakes in great shape out-brake discs. But when they get wet, wear, overheat and fade, drums become no better than (and sometimes not even as good as) discs. All the improvements discs are making (twin calipers, dual-pot calipers, dual rotors) are simply attempts to equal the swept area of the common drum brake, which will always out-brake them when all other factors are equal.

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PostPosted: Sat May 20, 2017 8:32 am 
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Location: rhode island
I agree, you wont get good braking on a dump truck using disc brakes, of course, seems like those drivers that crashed need more driving training. They have all those gears for a reason, to down shift, and also use the Jake Brakes, and just use the brake intermittently. How many times I'm going down a hill following someone riding there brakes, stinking up the hi-way.....and I haven't even touched mine yet. :roll: I stay back and let the engine do the work. BTW, 1979 was the first Z car model to have all disc brakes. I actually learned to do disc brakes way before drum brakes, my first drum brake job was on a 1957 Corvette, and at that time it sucked, and it sucked more when I took off the front tires :shock: ......and this Monday I'm doing the drum brakes on my truck......and it will suck again. :evil: springs, who the heck came up this idea. :? once together and adjusted correctly, then it's all good. 8)


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PostPosted: Sat May 20, 2017 2:09 pm 
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Joined: Wed Apr 09, 2008 5:53 pm
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Location: CT
Here's someone else's thoughts on a 4-wheel conversion:

"For years now, four-wheel disk brake conversion kits have been available. Installed properly, they work great. Here's the pro and con list for converting.

PRO

1. Quick pad changes at the track or in the driveway.
2. Easy visibility of all parts to see damage, leakage, etc.
3. Better brake cooling.
4. Better water shedding.
5. Better straight-line braking stability when hot.

CON

1. Rear handbrake system not available on some low-cost kits.
2. High performance rear brake pads unavailable or hard to find.
3. Rear disk and hand brake caliper unit heavier in many cases than rear drums.
4. Front disk-rear drum combo works great as is, + no master cylinder change.
5. Simple mods make rear drums more effective, such as slave cylinder upgrade and swept area drilling".

That's the first time I ever heard anyone suggest this swap might need a master cylinder replacement. I don't think I've ever talked to anyone who said they had to do that.

Paul?

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PostPosted: Thu May 25, 2017 7:56 am 
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Well from personal experience, I have no issues with #'s 1-3 in the "Con" list as far as #4, yes, but still doesn't say it's better, just good the way it is, and #5, Yes you can upgrade, but still doesn't say better and then you have all 5 Pro's against the #5 anyway. So looks like Disc brakes as an upgrade to sports cars wins, but doesn't mean drums are bad. As far as the master cylinder, bigger is better when it comes to disc brakes and a bigger booster. Drums require less force.....so there's one for the con list. :thumbs_up: Today I will be doing the drum brakes on my Truck..........yippee, I can't wait. :roll: Even though the front brakes were easy, it took me awhile because I knew I had to do drum brakes next. :(


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PostPosted: Sun Jun 11, 2017 9:21 pm 
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Location: CT
Is this project competed yet? What were the results?

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PostPosted: Mon Jun 12, 2017 12:00 am 
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Joined: Fri Sep 23, 2011 2:10 pm
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Location: Tolland, CT
:thumbs_up: Yep, just finished, drilled/slotted rotors both ends. Have not yet
had chance to put miles and "brake in". Hopefully can get it out by Wed.
after heatwave. I'll report back
Thanks for asking, Jack

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