80 CALIPER

Date: Tue, 17 Mar 1998 10:31:33 -0500

From: "Bartz, Paul" <s9d3452#mail.drms.dla.mil>

Subject: RE: GMC: Brake Job

Here are the part numbers I have for changing to larger front wheel calipers:

80 mm caliper:

GM NAPA Wagner

Left side 18015385 42-2072 CR98955

Right side 18015386 42-2073 CR98954

Caliper mounting bolt:

5468228 F98435

Flexible hose:

Left side 9762801 36-952 F110424

Right side 9762802 36-957 F110425

If changing to a larger caliper, there is some additional hardware needed (e. g. 1/4 " ss bolt and nut to secure the hoses, 1/2 " washer for the upper ball joint (replaces the original flex hose mounting tab), hose jam nut, crush washers and bolt to secure the hose to the caliper).

Having given the above info, a larger master cylinder (from the Chevy P-30 chassis) and adjustable brake rod (goes in the chamber between the master cylinder and the brake booster) (or a rod cut to length), increased, I believe, 0.010 " greater than the original length, is required.

Master cylinder (34 mm):

14009146 39-622 F103239

A master cylinder mounting bracket needs to be fabricated in addition. Help on that requirement is available upon request.

Now, are you still interested???????

Paul Bartz

- ------------------------------

Date: Thu, 28 Jan 1999 06:55:04 -0800

From: "Terry & Skinner" <fairwind@worldnet.att.net>

Subject: GMC: 80 mm caliper

I was looking at the 80 mm caliper on

http://www.gmcmotorhome.com/commodore/front_brake/index.html

Where does this caliper come from? Does it work well? I am not into changes just for the sake of change, but it looks good. Old saying from Alaska Airlines days. " If it an't broke, don't fix it."

Terry & Diane Skinner

Web-footed in Washington

'76 Glenbrook

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Date: Thu, 28 Jan 1999 11:11:23 PST

From: "Frank Folkmann" <fmfolkmann@hotmail.com>

Subject: Re: GMC: 80 mm caliper

Terry.

I am changing to 80mm. The best price is at AUTO ZONE Part #90184 and #90185 $12.99 plus core. These are remanufactured in Canada. Have a lifetime Waranty?..............FRANK

>to a machine shop and would prefer to make my own. Keeps me out of the tavern.

>Terry Skinner

>Webfooted in Washington

>'76 Glenbrook

>

Date: Thu, 28 Jan 1999 14:39:54 EST

From: duane m simmons <simmee@juno.com>

Subject: Re: GMC: GMC Motorhome Digest V2 #219

Chuck

I just replaced my Relay/control arm with a rebuilt one from Ken Thoma. He replaces the rubber bushing that attaches to the Drag Ling (aft of the pivot point of the relay arm) with a special made pin & brass bushing w/grease zerk. His units have been on the road for several years w/o

failure & provides better control. Cost is about $100 + shipping. Complete rebuilt unit ready for installation. I am very happy with mine.

Duane

------------------------------

Date: Thu, 28 Jan 1999 14:39:54 EST

From: duane m simmons <simmee@juno.com>

Subject: Re: GMC: GMC Motorhome Digest V2 #219

Thomas G Warner

I just don't endorse any one to copy a man's set of tools & advertise them for sale at any price. It's one thing to copy a set for yourself (one shot) and another to copy a set & sell them, even at a loss. Have you considered contacting him for a quanity price or getting his permission for fabricating a copy of his tools ??? Also a less expensive method of obtaining a set of tools is to share with two other GMCer since they are not needed very often, every 25 to 30k miles.

My 2 cents worth.

By the way Ken Thoma doesn't need our business for income. He is doing the community a great service with his expertise in rebuilding Front Wheel Bearing parts. More of a retirement hobby for him.

Duane Simmons

------------------------------

Date: Thu, 28 Jan 1999 15:19:58 EST

From: EMERYSTORA@aol.com

Subject: Re: GMC: 80 mm caliper

Wouldn't the use of a larger caliper require the use of a larger capacity master cylinder? I understand the idea is to get more pressure on the front brakes but this combined with the use of a 1-1/16" wheel cylinder on the front rear axle might be exceeding the capacity of the standard master cylinder. I have done the rear wheel cylinders and am thinking of doing the front calipers. Would any of you that have done this please advise as to what you did with the master cylinder.

Emery Stora

77 Kingsley

Santa Fe, NM

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Date: Thu, 28 Jan 1999 15:43:42 -0500

From: Zachary Zehnacker <zakz@erols.com>

Subject: Re: GMC: 80 mm caliper

Emery,

We did the larger wheel cylinder on the front rear bogie wheels a while back. We added the larger front calipers during the frame off. We are still using the standard size master cylinder. IIRC, the two reservoirs of the master might be separated, so an "upgrade" to the front shouldn't

affect an "upgrade" to the rear as far as the master is concerned. We haven't had any problems so far (~14,000-15,000 miles). We have good shoes on the rears and put on new Performance Friction pads with the front calipers though, so I can't say what will happen when the brakes wear down. If past wear rates are any indication (very slow), it will be a long time before we find out.

Zak

------------------------------

Date: Thu, 28 Jan 1999 16:48:56 -0500

From: davegreenberg1@juno.com

Subject: Re: GMC: 80 mm caliper

I had the larger calipers and wheel cylinders installed on my coach about 5 years ago and when I finally had to replace the master cylinder it was with the standard model. I have great braking; even before the changes ere made I had great braking.

David Lee Greenberg F22009

GMC Motorhome Registry

200 MacFarlane Drive PH4

Delray Beach, FL 33483-6829

------------------------------

Date: Thu, 28 Jan 1999 15:20:44 PST

From: "Frank Folkmann" <fmfolkmann@hotmail.com>

Subject: Re: GMC: 80 mm caliper

Emery. I am also changing master cylinder Auto Zone #706895 $55.43 plus core

..................Frank

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Date: Thu, 28 Jan 1999 21:05:15 -0500

From: Ted Schurman <tedsch@erols.com>

Subject: Re: GMC: 80 mm caliper

Zak, I don't think the wear will have any effect as long as the backs adjust and you add fluid to the reservoir to compensate for the wear.

Ted Schurman

73 Glacier VA

-----------------------------

Date: Fri, 29 Jan 1999 11:15:59 -0500

From: "Bartz, Paul" <s9d3452@mail.drms.dla.mil>

Subject: RE: GMC: 80 mm caliper

Frank:

I called local Autozone and got same price as you quote. However, when I asked them to give me the GM part number all they could give is a "C" number, which I gather is another supplier.

Question I have for you is how do you know that the numbers you give are for the right caliper? GM numbers are 18015385 left side, and 18015386 for the right side. I also have NAPA and Wagner equivalent numbers.

Paul

 

From: Frank Folkmann [mailto:fmfolkmann@hotmail.com]

Sent: Thursday, January 28, 1999 2:11 PM

Subject: Re: GMC: 80 mm caliper

Terry.

I am changing to 80mm. The best price is at AUTO ZONE Part #90184 and #90185

$12.99 plus core. These are remanufactured in Canada. Have a liftime

Warranty?..............FRANK

 

From: "Bartz, Paul" <s9d3452@mail.drms.dla.mil>

Subject: RE: GMC: 80 mm caliper

Date: Thu, 28 Jan 1999 15:41:27 -0500

Frank:

At that price, you better buy all the caliper's you can afford and then go into business selling them!!!!!!

 

From: Frank Folkmann [mailto:fmfolkmann@hotmail.com]

Sent: Thursday, January 28, 1999 6:24 PM

Subject: RE: GMC: 80 mm caliper

Paul. I could hardly beleive it myself. Checked 5 local suppliers and that's Auto Zones price $12.99.............Frank

 

From: "Terry & Skinner" <fairwind@worldnet.att.net

Subject: GMC: 80 mm caliper

Date: Thu, 28 Jan 1999 06:55:04 -0800

I was looking at the 80 mm caliper on

http://www.gmcmotorhome.com/commodore/front_brake/index.html

Where does this caliper come from? Does it work well? I am not into changes just for the sake of change, but it looks good. Old saying from Alaska Airlines days. " If it an't broke, don't fix it."

 

Date: Fri, 29 Jan 1999 09:09:30 PST

From: "Frank Folkmann" <fmfolkmann@hotmail.com>

Subject: RE: GMC: 80 mm caliper

Paul.

The calipers are from a Chev 1985? 3/4 and 1 ton with the 13" rear drum brakes. The origional info came from Arch. He gave me Napa #. I just went from there and ended up with the Autozone #. If my information is wrong please let me know.............Frank Going to call Bobby

Sunday to check if we can do machine work on my disc brake conversion

------------------------------

Date: Fri, 29 Jan 1999 09:54:00 PST

From: "Frank Folkmann" <fmfolkmann@hotmail.com>

Subject: GMC: 80mm caliper

Paul.

Lets start over again. The only reason that I mentioned the drum brakes is. The Gm 3/4 and one ton truck with 13" rear drum bakes have the 80mm caliper up front and also the larger master cylinder. Checked the casting #. They are18003532 GM L and 18003533 GM R. Your Gm # have have a 1 digit instead of the two 00. Paul I believe that they are the correct parts but I will check them again. Will cross reference the Gm # at Napa and then ask what year the are for. May be you can e-mail Napa part #. I could then do it over the phone. Paul I understand you are a good friend of Bob. Do you think that I should just go ahead and have the work done locally

Frank SW Indiana

Home of Toyota

TUNDRA

 

Date: Fri, 29 Jan 1999 13:54:58 -0500

From: "Bartz, Paul" <s9d3452@mail.drms.dla.mil>

Subject: RE: GMC: 80mm caliper

Frank:

Thanks for the clarification. Now I understand.

GM numbers I gave are different than your numbers, if you check, and I realize you say casting numbers. Last four of the numbers are 5385 for the left side and 5386 for the right side. Don't know what relationship casting numbers are to part numbers???

NAPA numbers I have are 242-2072 for left and 242-2073 for right sides.

As far as Bobby is concerned, I recommend you contact him and find out if he

feels up to helping you. Or maybe you would care to go to his place and do

the work??

Paul

------------------------------

Date: Fri, 29 Jan 1999 11:01:17 PST

From: "Frank Folkmann" <fmfolkmann@hotmail.com>

Subject: RE: GMC: 80mm caliper

Paul.

I am going to Napa and check Napa# as to year of application. Let you know if Auto Zone # are the right ones.......Going to call Bobby right now to find out how he is................Frank

 

Date: Fri, 29 Jan 1999 14:20:52 EST

From: EMERYSTORA@aol.com

Subject: GMC: Brake hoses for 80mm calipers

I see from Arch's pictures on http://www.california.com/~eagle/ that the brake hoses take a banjo fitting and require modification by bending. Does anyone have the part numbers for the hoses? I will be adding the new calipers in the next couple of weeks. Thanks in advance.

Emery Stora

77 Kingsley

Santa Fe, NM

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Date: Fri, 29 Jan 1999 14:29:18 -0500

From: Ted Schurman <tedsch@erols.com>

Subject: Re: GMC: Air Suspension Update - new compressor options

The question was asked earlier but I don't remember seeing an answer. Will the compressor generate the volume of vacuum (if that makes sense) sufficient to operate the brakes? The primary requirements of the pump, to generate a little bit of air under high pressure, is quite different than the large volume of air at low pressure drop required for the brake booster. The booster has a large surface area and moves a significant distance therefore requiring large volume.

Ted Schurman

73 Glacier VA

 

Date: Fri, 29 Jan 1999 15:45:31 -0500

From: "Bartz, Paul" <s9d3452@mail.drms.dla.mil>

Subject: RE: GMC: Brake hoses for 80mm calipers

Emery:

In addition to the banjo bolt (GM 15630743), you need crush washers (two

different sizes since the bolt is stepped), hose end jam nut, and a =BC =

x 1" bolt and nut to secure the hose tab.

Hose number: GM 9762801/NAPA 36-952/Wagner F110424, left side and

9762802/36-957/F110425, right side.

Paul Bartz

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Date: Fri, 29 Jan 1999 13:00:33 PST

From: "Frank Folkmann" <fmfolkmann@hotmail.com>

Subject: RE: GMC: Brake hoses for 80mm calipers

AUTO zone brake hose 3751339 77320 AND 3751347 77421 $24.99 each

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Date: Fri, 29 Jan 1999 13:07:01 PST

From: "Frank Folkmann" <fmfolkmann@hotmail.com>

Subject: GMC: 80mm caliper

Paul.

Returned from doing my follow up. Napa # are for 79-95 Chev and GMC but not all applications. Auto Zone 79-87 C-10 C-20 With 13"x2 1/2" rear shoes will give you the 80mm front caliper at $12.99.

Frank SW Indiana

Home of Toyota

TUNDRA

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Date: Fri, 29 Jan 1999 16:11:08 -0500

From: "Bartz, Paul" <s9d3452@mail.drms.dla.mil>

Subject: RE: GMC: 80mm caliper

Frank:

I'm picking up one caliper, using your Autozone numbers, from our local Autozone store on my way home from work.

I'll compare it to what I have on the coach this weekend and let you know. It may be Monday before I get back to you.

Paul

 

From: Frank Folkmann [mailto:fmfolkmann@hotmail.com]

Sent: Friday, January 29, 1999 4:07 PM

Subject: GMC: 80mm caliper

Paul.

Returned from doing my follow up. Napa # are for 79-95 Chev and GMC but not all applications. Auto Zone 79-87 C-10 C-20 With 13"x2 1/2" rear shoes will give you the 80mm front caliper at $12.99.

------------------------------

 

Date: Mon, 1 Feb 1999 14:31:23 -0500

From: "Bartz, Paul" <s9d3452@mail.drms.dla.mil>

Subject: GMC: FW: 80mm caliper

Frank:

Picked up the 80 mm caliper and a hose from Auto Zone.

Yesterday, I took off the right front wheel on the coach and removed the caliper mounting pins, pulled the caliper back out of the way and mounted the new caliper in place. It works. The hose was the right one also, with the proper end on it to mount to the caliper. Incidentally, I believe if

you look closely, the first 3 in the casting number you listed is really an 8. Look again and you can see that the 3's have a flat top to them whereas the 8 has a rounded top.

I'm going to call Leigh Harrison and talk to him about the caliper and hose. The NAPA hose (part number from Leigh) I picked up over a year ago as a spare, did not have the proper end on it and would not work on the caliper.

Paul

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Date: Mon, 1 Feb 1999 14:53:10 EST

From: EMERYSTORA@aol.com

Subject: Re: GMC: FW: 80mm caliper

Over the weekend I picked up a pair of 80 mm calipers and hoses from AutoZone using the part numbers that had been posted to GMCnet. They are the right ones. The protrusion on the top of the caliper must be ground off to provide clearance for the wheel. They wanted to charge me $12.99 for one caliper and $25.98 for the other and it took about 20 minutes for them to finally override the price in their computer. They should be 12.99 each.

As to casting numbers, everyone should be aware that casting numbers are not part numbers and there is often no relationship whatsoever to part numbers. In fact, identical parts could have different casting numbers. When the industry casts parts each mold will have its own casting number. This also applies to rubber parts. The casting number is shown on the part so that when

the company does quality control and finds that a part is not within specifications, they know which mold needs repair or replacement. If anyone needs parts numbers those of us who have the GMC parts book or the listing in the GMC International parts booklet will be happy to give what assistance we can.

Emery Stora

77 Kingsley

Santa Fe, NM

 

Date: Mon, 01 Feb 1999 13:34:16 PST

From: "Frank Folkmann" <fmfolkmann@hotmail.com>

Subject: Re: GMC: FW: 80mm caliper

Paul... Glad that you took the time to try the fit. You had me 2nd guessing myself. Do we now have a new source for 80mm calipers at a rock bottom price...................Frank

 

From: Frank Folkmann [mailto:fmfolkmann@hotmail.com]

Sent: Friday, January 29, 1999 12:54 PM

Subject: GMC: 80mm caliper

Paul.

Lets start over again. The only reason that I mentioned the drum brakes is the Gm and one ton truck with 13" rear drum bakes have the 80mm caliper up front and also the larger master cylinder.

Checked the casting #. They are 18003532 GM L and 18003533 GM R. Your Gm # have a 1 digit instead of the two 00. Paul I believe that they are the correct parts but I will check them again.

Will cross reference the Gm # at Napa and then ask what year they are for.

Maybe you can e-mail Napa part #. I could then do it over the phone.

------------------------------

Date: Mon, 1 Feb 1999 17:58:25 EST

From: Adohen@aol.com

Subject: Re: GMC: FW: 80mm caliper

In a message dated 2/1/99 5:49:43 PM Eastern Standard Time, EMERYSTORA@aol.com

writes:

> Scott

> The numbers are: Autozone # 90184 and # 90185 for the calipers. # 77320 and #77421 for the banjo hoses

Thank you Emery for the whole post. I printed this one. Now there is less chance of me deleting it. Now I can just loose it somewhere!

Scott Adohen@aol.com

------------------------------

 

Date: Mon, 01 Feb 1999 20:05:15 -0500

From: Patrick Flowers <patri63@ibm.net>

Subject: Re: GMC: Legalities of change to 80 mm calipers

EMERYSTORA@aol.com wrote:

>

> I am in the process of installing my 80 mm calipers and hoses that I purchased from Autozone this last weekend.

>

> I was talking to Wes Coughlin at Cinnabar about another topic and mentioned the 80 mm calipers. He indicated that we could have a tremendous liability if the brakes failed and there was an accident. Apparently, modifications to a vehicle can create a situation where the vehicle no longer meets DOT (Dept of Transportation) standards for the vehicle.

>

> I am not a lawyer<snip>

Hmm. Neither is Wes. Neither am I for that matter, but I've got 20 years in the insurance industry.

> Do any of you have thoughts to share on this?

Well, based on this definition of liability, you'd have the same exposure by doing your own maintenance. If you're in an accident, and it's your fault, then you're liable, period. That's why you carry insurance. Having modified your vehicle, either by replacing brake calipers, brake shoes, wheels, tires... (you, get the idea) is unlikely to increase your liability.

Like you, I didn't let Wes' opinion stop me from improving my coaches brake system. But then, like I said, I'm no lawyer so don't confuse the above with legal advice(don't want to be accused of practicing law without a license).

Patrick

- --

Patrick Flowers

Mailto:patri63@ibm.net

 

Date: Mon, 01 Feb 1999 20:22:08 -0500

From: John Wright <powerjon@tm.net>

Subject: Re: GMC: Legalities of change to 80 mm calipers

Wes has a tendancy to disapprove of anything that was not on the original design and that he didn't design himself and sell from his operation. The DOT answer is Wes answer to anything that someone else designs and builds. Don't get me wrong, Wes is a good engineering, but he sometime is too conserative in his opionions and that is my opinion.

J.R. Wright

------------------------------

 

Date: Tue, 2 Feb 1999 20:46:38 -0700

From: D & D Lowry <dlowry@silcom.com>

Subject: GMC: 80mm calipers

Sorry for the dumb questions, but I think I missed the beginning of this thread.

Are the 80mm calipers better because they provide more contact area than the OEMs? Are they direct bolt on replacements for the OEMs, using the OEM discs?

If answers are yes, at $12.99 per wheel, plus hoses and pads, this sounds like an exceptionally inexpensive upgrade to the OEM front disc brakes and I'm going to start rounding up the parts for my next brake job.

Here I go again.

TIA

Dave (& Dege), Santa Barbara, '76 Royale 26'

 

Date: Wed, 3 Feb 1999 12:23:42 EST

From: EMERYSTORA@aol.com

Subject: Re: GMC: 80mm calipers

In a message dated 2/2/99 9:45:25 PM, dlowry@silcom.com writes:

<< Are the 80mm calipers better because they provide more contact area than the OEMs? Are they direct bolt on replacements for the OEMs, using the OEM discs? >>

It is not the contact area because the pads would have the same contact. The pressure in the hydraulic system is proportional to the area of the piston in the caliper. So, a larger caliper will exert more pressure on the pads and result in faster braking and/or less pedal pressure for the same braking.

Emery Stora

77 Kingsley

Santa Fe, NM

------------------------------

Date: Wed, 03 Feb 1999 11:55:18 -0800

From: LARRY DTIMOTHY <ltim@bellsouth.net>

Subject: GMC: change to 80 mm calipers

Thomas G. Warner wrote:

> ...In my case I look at every suggested change to the coach from the > following perspective.> 1. Is it safe to use...

At what point in piston size would the available force applied to the caliper approach a potential jeopardy of breaking it?

Timothy

N.W. Fl.