George Buick Riviera

Disc brake for Max Trac, 71 Boattail

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Hi,

Disc brake for Max Trac option: driver's side disc has additional ring with holes in it, for the sensor pulses generation. My question is:

a) are such versions of the disc available ?

b) or is it possible to move the ring to the new disc ?

 

Anyone done that ?

image.png

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I don't recall this question ever coming up. Not sure if you got an answer yet or figured it out but I haven't heard of a special rotor for Max Trac equipped cars. Doesn't seem like Buick would do that???? I am guessing the notched disk for sensor can be removed and transferred to the new rotor. Let us know what you determine. how does the plate appear to be secured?

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Jason,

I need to clean the brake disc and inspect how the notched ring is fixed there. I hope it is just pressed into the standard rotor. I will update the thread after my inspection.

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Hi George,

  The Buick parts book lists a different LH rotor for the Max Trax application and does not break down individual components like a reluctor ring(see attached). This does not mean that things didnt change several years after the publication of this parts book (1971) at the dealer parts dept.or that the aftermarket didnt offer separate components over the counter....but at least you could start with a search for NOS using the part number,

Tom Mooney

20191030_153348_resized.jpg

20191030_153326_resized.jpg

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4 hours ago, 1965rivgs said:

Hi George,

  The Buick parts book lists a different LH rotor for the Max Trax application and does not break down individual components like a reluctor ring(see attached). This does not mean that things didnt change several years after the publication of this parts book (1971) at the dealer parts dept.or that the aftermarket didnt offer separate components over the counter....but at least you could start with a search for NOS using the part number,

Tom Mooney

 

 

Thanks for reminding me Tom, I have a book that has an effective date of May 1981. It does show the number you posted was superseded.

 

749615172_HUBDISCASSEMBLY-1971.thumb.jpg.bf37d08d5c6f56a6b8e9f6629a352cb1.jpg

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On 10/28/2019 at 3:37 AM, George Buick Riviera said:

Hi,

Disc brake for Max Trac option: driver's side disc has additional ring with holes in it, for the sensor pulses generation. My question is:

a) are such versions of the disc available ?

b) or is it possible to move the ring to the new disc ?

 

Anyone done that ?

 

 

George,

 

I have never seen one of those rotors with the Max Track, so I am NO help with how it is put together.

 

But I did a Google search for the number listed in the ’81 book, 6274216, and it came up showing the part number available. I didn’t check into it any further, but if you want to see if it is “actually” available, and it “actually” fits, here is a link to the website.

 

Brake Disc For GM 6274216

 

Good Luck, let us know how it turns out.

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Wow … how many cars would that revised part have served? Of course, nobody (including Buick) could decide how to spell MaxTrac.

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1 hour ago, Rivman said:

 

Thanks for reminding me Tom, I have a book that has an effective date of May 1981. It does show the number you posted was superseded.

 

749615172_HUBDISCASSEMBLY-1971.thumb.jpg.bf37d08d5c6f56a6b8e9f6629a352cb1.jpg

Randall,

  The superceded rotor part numbers are the same left and right so it would be interesting to see if  BOTH rotors had the reluctor ring or Buick substituted a standard rotor as a replacement, effectively disabling the Max Trac function in favor of simply supplying brake parts...or perhaps the assumption was the original reluctor wheel would be transfered to the superceded rotor? Certainly applies to very few cars...interesting,

Tom

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Thank you guys for all your efforts. The second disc in my car (passenger side) is standard indeed. Here is one more picture of MaxTrac disc - I have no more pictures right now with me, and I am away from home for some time. But I will let you know how it turns out.

 

The first owner of the car was a Buick dealer (his private car), so he ordered almost every option for himself. Looks like only sunroof is missing (GS, MaxTrac, automatic AC, external thermometer in the mirror, compass, bucket seats, cornering lights, triple front positioning lights, rear glass blower, etc, etc, - many many things are there plus some dealer options like alarm). Then he sold the car to his employee who was not using the car too much (car was stored for many many years). I am 3rd owner and I think all that is the reason, why this disc is still there.

disc II.jpg

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8 hours ago, 1965rivgs said:

Randall,

  The superceded rotor part numbers are the same left and right so it would be interesting to see if  BOTH rotors had the reluctor ring or Buick substituted a standard rotor as a replacement, effectively disabling the Max Trac function in favor of simply supplying brake parts...or perhaps the assumption was the original reluctor wheel would be transfered to the superceded rotor? Certainly applies to very few cars...interesting,

Tom

 

Tom,

 

I believe you are correct about the replacement number being the “standard” rotor.

 

I noticed, after I posted the page, the number used on the “with” wheel spin control, is the same as the number listed for the “exc” wheel spin control cars.

 

2004583338_HUBDISCASSEMBLY-1971-2(2).thumb.jpg.0a4fba1909063c21315731ba0abc8924.jpg

SO, either the ring can be transferred to the replacement rotor, OR yes, they were disabling the Max Trac?

 

Sorry George, it looks like what I found as “available” is the standard rotor. I can’t tell from the pictures if the ring can be moved to a new rotor or not?

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George,

  Looks like that reluctor wheel is a press fit on the hub. That would be very typical in many applications. I would heat up the reluctor wheel with a fairly hot heat source, like at least MAP gas, and use a "lady`s foot" type of prying tool to lightly work the wheel off the hub a little at a time, prying the wheel at various places around the hub....just be careful not to bend it up, if needed use more heat.

  Install the wheel by doing the reverse...heat up the reluctor wheel and drop it onto the hub and allow it to cool so the press fit is restored, just make sure the reluctor wheel if fully seated on the hub in the proper location.

  It would probably be a good idea to measure the OD of the hub on the replacement rotor to be sure it compares to the original.

  Good luck!

Tom

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On 10/31/2019 at 3:01 PM, 1965rivgs said:

George,

  Looks like that reluctor wheel is a press fit on the hub. That would be very typical in many applications. I would heat up the reluctor wheel with a fairly hot heat source, like at least MAP gas, and use a "lady`s foot" type of prying tool to lightly work the wheel off the hub a little at a time, prying the wheel at various places around the hub....just be careful not to bend it up, if needed use more heat.

  Install the wheel by doing the reverse...heat up the reluctor wheel and drop it onto the hub and allow it to cool so the press fit is restored, just make sure the reluctor wheel if fully seated on the hub in the proper location.

  It would probably be a good idea to measure the OD of the hub on the replacement rotor to be sure it compares to the original.

  Good luck!

Tom

 

My thoughts exactly Tom. After seeing the rotor cleaned up, it does look like it is pressed on?

 

Use the heat you suggested, and possibly use a three or four arm puller, of some kind, carefully, and see if that will get it off. Of course, that would be after measuring the diameter to make sure it would fit at all first.

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Saw a post on a different Buick forum where the guy has a hot plate in his garage and uses it to heat parts (and a freezer to cool the other parts) when removing / installing press to fit parts. He claims the hot plate does a better job of heating the part overall than the spotty heat he was getting using gas. Plus you can walk away and do other stuff while the part is heating up.  

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Guys,

after heating up (not even that much), the reluctor wheel went off super-easy: using just the screwdriver it was possible to "twist it out" from the hub, no prying was necessary.

Both hubs have the same OD, however the hub for non MaxTrac disc is rounded on the bottom, while for MaxTrac disc the hub is more perpendicular at the bottom - I think to have the support base for the reluctor wheel, after it is pressed in.

 

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Edited by George Buick Riviera (see edit history)
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Can anybody explain how the Max Trac works?  Is this system utilizing a computer? Talk about an obscure option!  

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2 hours ago, George Buick Riviera said:

Guys,

the MaxTrac reluctor fits perfectly the new disc.

 

image.thumb.png.61f020618c388785ec98437c3b0bb03d.png

 

Thanks George for following up. Safe to say many of us learning something new.

 

 

1 hour ago, Seafoam65 said:

Can anybody explain how the Max Trac works?  Is this system utilizing a computer? Talk about an obscure option!  

 

Yep an early "ECM" though it wasn't referenced as that. Sensors in transmission and 1 front wheel as inputs and the output was choking off the ignition to reduce power.

Likely no one back in 71 could imagine how much computers would become engrained in automobiles controlling everything.

Edited by JZRIV (see edit history)
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3 hours ago, JZRIV said:

 

Thanks George for following up. Safe to say many of us learning something new.

 

 

 

Yep an early "ECM" though it wasn't referenced as that. Sensors in transmission and 1 front wheel as inputs and the output was choking off the ignition to reduce power.

Likely no one back in 71 could imagine how much computers would become engrained in automobiles controlling everything.

Wow Jason.....never heard of a computer being on a GM car before the Cadillac fuel injected engines came out in 1975.......Just when I thought I had seen everything.......

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After doing some internet research, I found out that they were calling the computer an "electronic controller" in

info GM published regarding the system that was first introduced on the 71 Riviera. I also read that the system was so trouble prone

that it was discontinued for the 1973 model year. I never heard of this system till now, but then I've never had a boat tail Riviera in my shop

before so I guess that's understandable. Since the system can malfunction and shut the engine down, if I had a car with that option I would

definitely remove it so as not to get stranded by it. Does anyone know if when it malfunctions you get a "Check Max Track" light on the dash?

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The system works this way, that the "computer" delays the ignition to reduce the engine's power, in case of the rear wheels are loosing the traction comparing to the front wheels.  I've heard that this was also the reason for cancelation of the option in 73, due to new emission standards.

There is a switch at the dash, and in case of malfunction of the system you could switch it off (switching off means bypassing the "computer").

The picture below is not very sharp, but you can see the switch there, just above the clock.

 

image.thumb.png.b2a8393d2d433aa937025c86a33c7392.png

Edited by George Buick Riviera
typo (see edit history)
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Thanks for posting! It's great that you can turn it off.....nowadays when stuff like this goes bad there is no way you can just turn it off....

lights and bells and buzzers continue to go off forever until you fix the problem nowadays.

Edited by Seafoam65 (see edit history)
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