Affordable rotor upgrade breakthrough coming soon to ISSCA SScene mag

Hey all, just a heads up that there is going to be an article in the next Impala SS Club of America (ISSCA) SScene magazine about a brake rotor upgrade you can do to your B-car very affordably using all GM parts (like under $200 and even less if you have connections to somebody with a lathe or brake lathe). It only requires one-time machining on two parts to complete the upgrade; everything else is bolt-on, and no further machining is required of consumable parts. This upgrade improves heat handling and dissipation in the front brakes, makes future rotor changes as easy and cheap as a FWD car, and eliminates the need to repack bearings every time you change rotors. There's also a sub-article about improving the wheel bearing preload procedure that will help you maintain optimum adjustment on your front wheel bearings, improving durability and steering feel.

ISSCA membership dues have dropped 25% to $30 this year. They cater to all '91-96 B-bodies including Caprices, Roadmasters, Olds Custom Cruisers, Fleetwoods, and the corresponding wagons. (They have also expanded their charter to cater to other year Impalas as well). Their national convention this year will be in Detroit August 18-21 which coincides with the Woodward Dream Cruise. Definitely a great event to go to if you can make it. You can join here.

Please note: I'm not trying to start a debate about the merits of ISSCA, only to let you know that there is a really cool article coming out soon that you may be interested in.

....TEASE!

I was hoping this was a rear rotor thread.

Come on Joel we are waiting!!!! Need details and part numbers...........

Join the club. It's worth it.

sherlock9c1 wrote:

Hey all, just a heads up that there is going to be an article in the next Impala SS Club of America (ISSCA) SScene magazine about a brake rotor upgrade you can do to your B-car very affordably using all GM parts (like under $200 and even less if you have connections to somebody with a lathe or brake lathe).

Sounds interesting, Joel--look forward to seeing this!

So like... Are they still actually printing the SScene?

They sure as heck better with all of the work we put into making that article.

I posted over on ISSF to see what the holdup is. We busted our butts to meet the publication deadline.

toomanytoyz wrote:

So like... Are they still actually printing the SScene?

I do hope they do, but if they don't (or most members don't get the mag like I did for almost 3 years...) I hope you share!!

Guys, I heard back from Ken (the SScene editor). He's had some health problems that put him out of commission lately. He will get the magazine out as soon as he can.

Well, amazingly, the information has not yet been leaked, so I figured now's the time to let the rest of you know what's going on.

I've only got a few minutes so I'll make it brief:

JaySS and I did a bunch of figurin' and found out that you can use 1990-2002 AWD Chevy Astro Rotors as a drop-in replacement. It increases the overall rotor thickness by 25% and increases the cooling vane area by 50%. Plus, Astro rotors are typically half the cost of B-body rotors. They drop right in IF you do the following steps:

1. Replace your calipers with J55 limo calipers to handle the extra thickness. (Search parts catalogs under 1996 Cadillac Commercial Chassis)
2. Take your old B-body rotors and cut the rotors off. Save the hubs and ABS rings and these will become your new hubs. If you have a friendly shop with a brake lathe, they may do this for you on their lathe for cheap.
3. Take the hubs and machine down the outside radius to fit inside the Astro rotor.
4. Buy 1/4" or 5mm wheel spacers and mount them between your B-body hub and the astro rotor to get the rotor properly located within the caliper. Check your clearances - Jay's set needed 5mm, mine needed 6.3mm (1/4").
5. Replace the studs with longer Dorman P/N 610-323 studs to accomodate the spacer and the Astro hat.
6. To concentrically locate the rotor, either be careful when you machine down the hub so the hat fits nicely over top, or use spacers around the lug studs made from McMaster-Carr steel-backed bearing PN 6679K17 (12mm ID / 14mm OD by 20mm long) and cut into sleeves the thickness of the hat + the spacer.
7. Be careful on pad choice. Several of the thicker 9C1 pads will are too thick even inside the J55 caliper.

I'll post more info and pics later. If you have questions, feel free to post them. At the rate Syracuse winters are eating my wagon's rotors, I may put this setup on my wagon too.

sherlock9c1 wrote:

Well, amazingly, the information has not yet been leaked, so I figured now's the time to let the rest of you know what's going on.......................

I'm missing something. If the Astro rotor is centered on the B-body rotor, what's to keep them from rusting together to form a solid mass?

I don't know how the ABS operates in the first place, so the description doesn't help me. Does the ABS work?

Looking forward to seeing those pics Joel.Can you shoot some from above the rotor and
caliper looking downward.A few pics of the stock setup the same way for comparison would
be awesome.Would make a lot of sense on a wagon that does a lot of towing like a certain
bare footed car wash guy who likes to camp.

Nick you cut the B-body rotor off the hub so you're left with only the B-body hub. You put the spacer in between the rotor and the hub which minimizes any corrosion concerns.

The ABS operates using reluctors (gears with block teeth that pass a hall effect sensor, generating a small AC voltage whose frequency is proportional to the wheel speed). Each wheel has one (well, on the B-bodies, the pinion gear in the rear axle has one). The ABS module monitors each reluctor and when one's rpm suddenly drops, the ABS module backs off the brakes on that wheel until the wheel speed comes up.

The beauty of this solution is that it maintains your stock ABS. Unfortunately GM used an odd-duck number of teeth on the B-body reluctors (34 teeth per wheel revolution) whereas they (and almost EVERYBODY ELSE, doh!) uses 55 teeth on their trucks and Astros. We were stuck on this problem for awhile because the ABS reluctor is pressed onto the back of the B-body rotor and the rotor is a wear item. We wanted to avoid having to machine anything that was a wear item. So the beauty of this is - you take your stock worn-out rotors (mine are crap anyway from Syracuse winters), cut them down, powdercoat them, and now you have hubs with ABS built in.

The other benefit of this is that you don't have to repack bearings every time you change rotors.

Oh and Jim, once it's assembled, it looks completely stock. Seriously.

What is the net gain in braking with this upgrade? I'm getting ready to buy a new set of rotors for Grimace and started looking at some different options (not that I need alot to stop a 305).

There won't be any braking improvement on the first stop. The rotor/swept area is the same size. The improvement will come with repeated hard stops where the increased mass will provide for greater heat dissipation.

Joel, if I don't care about ABS, is there an easier way to do it? ABS is long gone from my SS.

Jayoldschool is correct - the net gain is in heat management and in serviceability. If I lived down south and my car was a daily driver, I would not be doing this mod.

I'm doing on my cars for two reasons:
1. I plan to road-race my 9C1 this summer and the stock brakes just can't dissipate the heat fast enough.
2. Syracuse winters are literally eating a set of rotors each season and I hate packing bearings every time I replace rotors, plus Astro rotors are cheaper and there are more Astros with good rotors showing up in junkyards (believe it or not!) than there are B-bodies.

Jason, ABS was pretty much a requirement so we didn't explore any option that didn't allow ABS.

For what it's worth, what we found was that the '96 Cadillac J55 brake package uses the '71-76 Caprice brake rotors that are 32.7mm thick vs. the '91-96 B-car 26.4mm. These rotors do NOT have the ABS tone rings pressed onto the backsides like the '91-96 B-car, which is probably partly why the J55 package doesn't have ABS. Then we looked at the bearings and found that the outer is the same but the inner (and the seal) is larger. I suppose then you could install J55 spindles from that '96 commercial chassis but new spindles ain't cheap, and you already get the same thickness from the Astro rotor. So you're not saving anything.

As I said above, GM appears to have used a different ABS unit with a 55-tooth standard on ALL of their trucks and vans, so any of the rotors from those packages would have incompatible tone wheels. If you didn't care about tone wheel tooth counts (which you don't), you could go through parts catalogs and explore the various GM truck and van rotors and see if you can find rotor offsets and bearing sizes that will work on the stock B-car spindle. It really wasn't that hard; we spent most of our time in the Centric, Brembo, and Napa online catalogs to find what we did.

The other option to search is this: After the article went to the publisher, we stumbled upon a NASCAR sportsman supply house and found a hat and rotor combo for dirt cheap that looked like it would fit. The 5x5" bolt pattern is a common size for those cars. I think the rotor thickness and weight was a little questionable on some of the available rotor choices but it was a logical next step. It stands to reason that they may have a non-ABS hub which might fit the B-car spindle and allow you a wider array of rotor choices.

BTW, for you appearance freaks, the other cool benefit is that the "rust ridge" disappears. The B-car rotors are 11.86" in diameter and the Astro rotors are 11.61". This works out to about 0.125" around the radius or 1/8", which is just about exactly the width of the rust ridge. All of the B-car pad combinations I tried on the Astro rotor matched up perfectly with the outside edge.

Some photos to better illustrate what is going on.

This was the cheapest & most easily accomplished method we could put together.

Cut the disc portion off of the B-body rotor, as has been done many times - Photo of B-body hub (with longer studs already installed):



Purchase longer studs and some thin spacers to shim the Astro rotor into the proper position:



Spacer on cut-down rotor (longer studs not yet installed):



AWD Astro Rotor used for this conversion (11.61" x 1.29" - 5 on 5" in bolt circle):



Photo showing unswept outer area on stock rotor:



That should help as a start to visualize what is happening, more pics and instructions can be posted as needed.

- J

Thanks Jay for the pics and description!

How much does the wheel offset with the installation?

gotcha on the heat dissipation. Not doing autocross or racing, so I guess I'll just use a regular set or maybe one of those cool looking rotors with the lines cut in 'em since you can see them soo much more with the imp rims...

The front wheels each move out about 1/2" - 1/4" for the Astro hat and 1/4" for the spacer.

That could be problematic with drop spindles, because they already move the wheels out 1/2 inch. One would need a 1 inch offset on top of the OEM offset.

Yep. We kept the cost in the basement on this one, and front wheel clearance is one of the tradeoffs we made. What we ran into (literally) is that the inboard caliper mounting ears on the spindle/upright hit the rotor if you don't space it out. So you could cut those ears off and save 1/4", but then you're talking new caliper mounting... and if you're talking new caliper mounting, then you're talking bigger rotors, bigger calipers, bigger $$$. That's the real constraint: the stock caliper mounts. One you cut those off, the sky's the limit, but then the mods are not reversible without changing spindles.

Thanks for posting this information and the pictures. Sticky-ing!

Fred Kiehl wrote:

That could be problematic with drop spindles, because they already move the wheels out 1/2 inch. One would need a 1 inch offset on top of the OEM offset.

From experience, a B-body with at least 1 inch lower springs, N97 wheels and a fairly good size tire will handle a 1-1/4 inch spacer on the front without issue. Not that it guarantees anything, but don't blow the issue out of proportion.

Some more info from the article:

1. Why did you choose to recommend this method to upgrade my brakes?

Answer: This solution is inexpensive, and although some initial machine work is required to make it happen, once the conversion is complete, any expected maintenance can be accomplished by purchasing readily available replacement parts.

2. Will this setup change my braking feel?

Answer: No. Only larger-diameter rotors or more aggressive pads will do that.

3. How much weight does this add? Is it all in the rotor?

Answer: I measured about 2.8 LBS difference per side (25.0 LBS to 27.8 LBS) when the hub, rotor, bearings, castle nut and washer were measured together. Only a small amount of that is attributed to the additional Astro hub face material. Most of it goes into the rotor. Dimensionally, the Astro rotor is 50% thicker in the vanes, 10% thicker on the outboard wear surface, and 5% thicker on the inboard wear surface.

4. Does this affect my track width?

Answer: Yes. Each side gets spaced out 5.5mm (rotor hat thickness) + 5.0mm spacer = 10.5mm or 0.413”. This is slightly under 7/16”.

5. I saw that the Astro rotor is only 11.61” in diameter vs. the B-body 11.86” diameter. Is this a problem?

Answer: No. In fact, all of the test-fitted D52, D153 or D614 pads in J55 calipers resulted in a perfect alignment along the outside radius of the rotor. The stock B-body rotor/pad setup has a rust ridge of roughly the same amount as the difference in radius.

6. Will this rotor keep me from boiling my brakes at the Nationals this year?

Answer: Possibly. Based on the numerous scientific papers available online, brake boiling occurs primarily due to fluid heating. You can lessen fluid heating by using cast-iron calipers (aluminum ones are more susceptible to heat conduction, note that all stock B-car calipers including JB9, JA9 and J55 are cast iron), inner pads which have at least 12mm of friction material on them, fresh high-quality brake fluid, and larger rotors with the most airflow you can fit within your design/budget constraints.

Compared to B-car rotors, AWD Astro rotors will heat up more slowly due to their greater mass/thickness and (most importantly) dissipate heat more quickly due to the larger vane openings. The other item to note is that rotors cool both inside AND outside at roughly equivalent percentages according to scientific research, since their hottest parts are located right at the wear surfaces.

Directing air to the rotor area and using wheels that block airflow as little as possible (such as Impala SS or the N97 police-spec wheels vs. base-level Caprice wheels) will also help. It should be noted that numerous fluid dynamics studies of airflow around brake rotors have found that increasing the passageway size is what increases cooling, not directional or intricate vane geometry. Anything you can do to ensure that fresh air can get to into the center of the rotor and exit out through the vanes will be helpful. Real world situations being what they are, don’t kill yourself trying to make it perfect, just do the best you can.

- J

More photos for your viewing pleasure...

Factory 9C1 Caliper & Rotor:


J55 Caliper - Astro Rotor - 9C1 (D614) pads - Top view:



J55 Caliper - Astro Rotor - 9C1 (D614) pads - Rear view:



Compare the original setup with the new combination. Observe the reduced clearance between the knuckle's inner mounting surface and caliper's pin boss. This illustrates how the caliper moves forward to accomodate the thicker rotor & fresh pads.

- J

Not to mention you can find performancd rotors for the astro rotors. Awesome upgrade on the cheap.

Is there a parts list for this mod. I have a buddy with a machine shop. I can do the rotors for a bit"o"cash ie(shipping) and exchange

Well, the Astro front brake rotor conversion successfully made it from Syracuse to Detroit and back and survived 60 miles of road racing while we were out there. A couple of comments for anyone following through on this:

1. The Milwaukee "torch" sawzall blade woked great, but it cuts SLOW. Took me 45 minutes to cut the rotor off the hub. Once I did that, a friendly tech at the local brake place turned it down in 10 minutes on a brake lathe.

2. I have one rotor/hub I cut down that sits far back on the spindle. Like, the ABS reluctor was rubbing on the dust shield. It did this on both sides so it's not a dust shield problem. The 5mm spacer I bought off Ebay was NOT thick enough to get the rotor out where it needed to be, so I went to Home Depot with my digital calipers and measured out a bunch of 1/2" flat washers and came up with enough that were 2.13-2.17 mm thick, then made stacks for three washers on each lug stud. This worked out to about 6.45mm which was enough to get the inboard pad in. I brought my torque wrench and torqued the wheels everytime we stopped on the trip out. There was very little extra movement on this particular wheel, so that was good. I saw no appreciable runout with this setup, FYI. Just keep an eye on this when you cut your hubs.

3. If you have fresh pads, you will need to grind them down on a belt sander or other creative method to fit. There must be negligible pad drag when you are done.

4. New calipers tend to have little bubbles hiding out inside. I bled the system three times before I left home, and then bled them again at the road course. A little tiny bubble makes a big difference in pedal pressure. FYI - you CAN bleed the front calipers without jacking the car up. Just turn the wheel all the way and you can reach in behind the tire and put a hose on the bleeder and crack it open. Worked like a champ.

5. Watch the caliper bolt mounting threads in the steering knuckle. Mine were full of crud for some reason and I had to clean them out real good before the slider pins would thread in nicely. You do NOT want these to strip out.

6. It is possible that, due to play in the pads, some of the pads might overhang the chamfer on the outer edge of the rotor. I will be keeping a close eye on this.

FYI - I just posted this article in its entirety (with pictures!) at the ISSF. Feel free to go read it here.

http://www.impalassforum.com/vBulletin/showthread.php?t=266855

I installed Astrovan rotors and Caddy calipers Monday after work. Took 3-1/2 hours. I purchased used calipers from a junk yard $30. Used Roadmaster rotors from another junkyard $40. Used 1987 Astro Van AWD rotors with 5,000 miles on them for $50. And Wildwood 5mm spacers for $32, much superior to aluminum spacers. Replaced Studs and bearings and made a non-castled nut for each side. Plus $36 for stud, bearings etc. Total $188 + $40 to cut off rotor surfaces Roadmaster rotor/hubs.

I sand blasted the Calipers and outside of Astro Van rotor hats and cut down Roadmaster rotors and painted with 2 coats of Aluminum Chassis Saver urethane paint. This took several months after work in between other household chores/projects and vacations.

Tuesday (yesterday) I sponged out all the old brake fluid from the Master cylinder, wiped out all of the black goo and replaced with DOT 3/4 fluid. I need to replace the anti rattle brackets for inner brake pads as the old ones were so corroded they would not stay on pad.

Thanks for the article.

Chris

Thank you to the ones that originally figured out and shared this upgrade.  I've now done it on my wagon (1995 Roadmaster Estate) and am very happy with the change.  While I was at it, I went a little further and got fancier calipers and brake hoses.  Here are some pictures, part numbers and things that I discovered along the way.  Hopefully this helps someone in the future and contributes to the knowledge base.



Wilwood D52 calipers. Made in USA, Kit# 140-11290-BK $313. They make them in several variations. Red or Black, narrower style that fit the original rotors and rear disk style that have much smaller pistons.  They are available individually for about $160, but for the price the kit basically gives you a set of premium pads for free.  If you get them, you want the wide ones for the astro rotor and with the bigger pistons to match the power of the original calipers.  For about half as much money they make a single piston version that is much closer in appearance to the original GM one.



If you get Wilwood calipers you will need new hoses. This took me the most time to get right since I could not find any complete information on what types of fittings that our cars have on them.  My car, a 1995 most definitely has BUBBLE FLARE fittings on the brake lines which I figured out later. I called Wilwood to see if they knew what hose kit I needed, but they had no information. You need a 12" long hose that has M10 X 1 bubble flare on one end and 7/16 x 20 banjo on the other.  I ended up buying the wrong Wilwood kit 220-13001 and separate fittings to complete the hoses. I would not buy the hose kit again now that I know that M10 x 1 IF (inverted flare) does not fit my car.  This picture shows the Wilwood 12" hoses with 3AN fittings on both ends and the Fragola ends from ebay.  Fragola makes their fittings in Connecticut and seem to be of high quality.



Rotors were about $95 after coupon for a pair direct from EBC.  I bought these rather than others thinking that the quality might be better and that they might be UK production.  They seem to be of high quality and if they hold up well through this winter they might be my go to brand for all rotors.  There is no indication of country of manufacture, but from the type of cardboard on the individual boxes inside, I suspect Chinese castings that get their final machining and coating in the USA.





The studs are ARP 1007708 ($32 for 10 of them) they fit the stock hub and stock lug nuts but are 2 1/2" long, about 1" longer than the stock studs. I would have preferred a little shorter. ARP makes 2 shorter versions but they are both new models that are about twice the price.  They make great stuff and ensure that there are no internal fractures that could cause failure in the future.  All of their products are made in house at their USA factory.  I'm sure that the dorman ones would be fine but they are over $20 for 10 which seems pricey for outsourced manufacturing from a brand that I've had mixed results.



I got the EBC Redstuff pads to get the best discount when I got the rotors.  I started out with them since they come with a bedding grit on the surface which would clean the black coating off faster.  I'll run the Wilwood pads later and post what was better.  The EBC ones come with adhesive backed noise reduction shims, the Wilwoods don't come with any shims.  EBC ones are made in UK the Wilwoods are from USA.





After installing all the parts and bedding the pads, I can't believe the difference in brake feel.  Since I changed all the components at once I can't say what part of the upgrade makes the biggest difference.  I suspect a combination of factors but I think that the pads may be the biggest part of the feel.  They start to bite with the slightest touch of the pedal.  All of the braking seems to be done by the power brakes and no real force from my foot is needed in regular stops.  Normally I don't drive in a way that bigger rotors are needed so I don't think that they help much but they do add some confidence.  My old hoses were shot and may have been adding to the spongy brake feel that I was used to.  I don't know about the calipers though.  They are really nice and are less than half the weight but the GM ones are a good design.  Rebuilt ones probably would have worked just as well.

Joel, as of my writing, 0726/2017, we can no longer see you pictures. This is due to the fact that Photobucket, where you were storing your photos, is now charging it's users $99.00 per year for the privilege of allowing users to post into forums. All my photos are the same way.

Dave

If anyone has photo hosting abilities I'll gladly email the pictures to you. But you should be able to do all this with the text info provided.

What about the clearance between the outer diameter of the rotor hat & caliper / pad?
The Astro rotor hat outer diameter looks to be about 0.24" larger than the stock b-body rotor/hub. There appears to be only about 0.164" clearance with stock setup.
If my number crunching is right, that would be a clearance of only about 0.044" with J55 Caliper on Astro rotor, does that sound right?
Are J55 Calipers for a 1996 fleetwood the correct ones for this mod, or is it a supposed to be a caliper off of a different vehicle?
Thanks