: 90-92 Brougham's: Need help with orig. part # id's. Master Cylinder & Wiper Arms!

07-14-13, 03:36 AM
Hey Guys,

This is really stupid and driving me crazy.:banghead:

I should probably post these 2 issues separately, but here it goes.....

1st, I've had problems with the wiper adjustment on this car since new so it could very well be that the arm wiper transmission mounting pivot was drilled and mounted wrong during assembly. The drivers side wiper would always hit the "A" pillar, or if readjusted, would hit the lower windshield park bracket and/or the wiper would go off the bottom of the windshield and make the annoying click on med/high speed.

Basically it seems like the d/s wiper has to long of a sweep which can't be adjusted unless something in the transmission linkage was bent originally.

Can someone who has a drivers side original wiper-arm pop it off and look for part#'s under the arm or on the arms side for both the d/s and p/s wiper arms?

There seems to be conflicting info from Dorman on replacement aftermarket arms including the one's I bought don't fit well. The d/s arm does not place the wiper perfectly parallel to the "A" pillar under high speed and wet windshield. This can be seen when the key is shut off when the wiper reaches maximum sweep and would probably need heated and bent if it is the correct part # to try and correct the geometry.


2nd problem: there is a cataloging problem from GM for the Master Cylinder on 90-92 Broughams, US models, with ABS with 11x2 rear shoes and JM4 Brake Option Code on trunk lid i.d. tag. I have discovered this is a very specific Master Cylinder for only 90-92 which is a "Quick Take Up" M.C. with other internal unknown specs.

Does anyone have an original master cylinder with a square cover?

If so, can a few of you guys take a clean piece of white paper, place it under the M.C. body, and run your finger under it to make an impression of the casting numbers....?[

Hopefully the dirt under the master will imprint the numbers on the paper. Even a store receipt that is thin shinny paper works well to make an impression.

Maybe even take a pen and rub the pens body over the paper when taking the impression to apply even pressure on the raised casting numbers.......a mirror would work, but hard to read backwards.

About 6 yrs ago, I went round and round with Caddy Dealership who sent me to the Delco Distributor because no once could definitely find the correct part number for the master cylinder.

This always bothered me about what M.C. they sold me since I've had brake problems, so I took the part #'s off the one they sold me and researched it again. Looks like they did sell me the wrong M.C. and it was for GM's/GMC's full size pickups/suburbans. The bore specs look to be the same, but who knows what else is different about it.

I also spent about an hour on the phone with 2 different techs at Raybestos who were certain which MC to give me as they remember a consolidation of this M.C., but I found out they are even wrong......

Your help is greatly appreciated.


07-14-13, 06:16 PM
Master cyl 1990 Brougham with JM4 code is:

18016429 43 A-50 This all on the bottom of master cyl. It has the rectangular lid. The right leg of the A is not sharp and clear. Sure this car has orig master cyl. Hope this helps.

07-14-13, 11:58 PM
Looking through RockAuto, I see reference to the part number, provided by skirts, only on '90-'92 GM/GMC 1500 series trucks. RockAuto isn't always right.

I checked AC DELCO and they have a master cylinder listed as 18M420, and they only list it as being use on '90-'92 Cadillac Broughams. AC DELCO updated a lot of their part numbers, so that might be the new number for the cylinder you are looking for.


My car has the same issue with driver's side wiper blade hitting the A-pillar. The problem started after I changed the wiper blades; when I got it, it still had the factory original wipers, and they had a perfect wipe pattern. The after market blades don't perfectly match factory specification and causes the blade to hit the trim on Hi speed.

07-15-13, 12:33 AM
Thanks Skirts!!!!!! What a beautiful car you have. Where did you get the "skirts"?

Your not going to believe this. I have the same damn casting number and even looked at it with a mirror in reverse but the middle number is different which I don't know what it means yet, but the first # is indeed a GM Part# that is hard for the Caddy dealer to look up but they were able to get some info to lead to another part#. It could also be a casting number that crossed over to a part number.

My M/C is: # 18016429 19 A 50

You might have a newer Master Cylinder also which very well maybe the wrong M/C too.... I really have to dig into this further and go in a different direction. I hope to find either a NOS M/C and get the numbers on the bottom, or hopefully some other original owner here on the forum will know for certain if they have an orig. M/C to check their numbers. I'll check with more sources to i.d. some master cylinders on the shelf to see if that casting number is on all the different M/C's and is just a generic "Casting Body Number" that all "Quick Take Up M/C's had.

I'm just not sure if our casting number has the "Quick Take Up Internal Valve" that is supposed to match the "Low Drag Calipers". Raybestos even told me that if I didn't have the original calipers (which I did change) that its a possibility that the whole aftermarket caliper industry did away with the specially designed pistons which matched the "Quick Take Up M/C! The Raybestos Techs couldn't even tell me if they still make the low drag calipers and I'd have to take them apart to see...........REALLY STUPID!!!!!!!

About 6 yrs ago, I totally upgraded my brakes trying to achieve better stopping. New Raybestos x-drilled/slotted rotors, Axxis Metal Master Pads, Raybestos shoes and hardware, Wagner Calipers & Wheel Cyl. with stainless braided hoses along with this new Delco Master Cylinder which looks like is not the right one! All those upgrades, and the car still doesn't stop for sh't which led me back to investigate this Master Cylinder part# issue.

Below are some links to read about the "Quick Take Up" MC. Apparently, here's how it worked. Somewhere in the early 80's thru 90's GM came up with a unique designed low drag caliper which caused the boot to retracted and suck the pads into the cylinder bore when not braking so they ride on the rotor for fuel economy. They then needed a feature in the MC to cause an initial pressure spike to quickly engage the pads as soon as the brake pedal would move. I just need to know if the M/C we have also has a "Quick Take Up Valve" inside but would actually need to either take it apart, or look at the factory service manuals for each application of the cross referenced trucks this M/C is supposed to be for. Now I'm going to have to verify IF low drag calipers are even still made as replacements in the aftermarket for this car!!!!!!!!!!!!!!
:gah: :gah:

I was told by the Caddy dealer that our number #18011649 crosses to a Delco #18M1746, GM # 19176356, and Raybestos crossed it on their website to a Raybestos #MC39646 which all fits these applications according to the RockAuto site and what the Caddy dealer saw also:

Buyer's Guide: ACDELCO 18M1746 Master Cylinder:

CHEVROLET C1500 PICKUP (1988 - 1994)
CHEVROLET C1500 SUBURBAN (1992 - 1994)
CHEVROLET C2500 PICKUP (1988 - 1994)
CHEVROLET C2500 SUBURBAN (1992 - 1994)
CHEVROLET K1500 PICKUP (1988 - 1994)
CHEVROLET K1500 SUBURBAN (1992 - 1994)
CHEVROLET K2500 PICKUP (1988 - 1994)
CHEVROLET K2500 SUBURBAN (1992 - 1994)
CHEVROLET R1500 SUBURBAN (1989 - 1991)
GMC C1500 PICKUP (1988 - 1994)
GMC C1500 SUBURBAN (1992 - 1994)
GMC C2500 PICKUP (1988 - 1994)
GMC C2500 SUBURBAN (1992 - 1994)
GMC K1500 PICKUP (1988 - 1995)
GMC K1500 SUBURBAN (1992 - 1994)
GMC K2500 PICKUP (1988 - 1994)
GMC K2500 SUBURBAN (1992 - 1994)
GMC R1500 SUBURBAN (1988 - 1991)
GMC V2500 SUBURBAN (1988 - 1991)
GMC YUKON (1992 - 1994)

:gah: :gah: :gah: :wtf::wtf::wtf::wtf::wtf:????

Anyway, I'll try to figure this out and have one very good and quick definite source to see what another Brougham had and a few other directions to go in.....

I just don't want mis-matched hydraulic parts on the car.

Here's those links:

This link has been recovered from an archive site but some of the images did not get archived. I'm going to call the publishing company of the trade magazine "Brake and Front End" to see if they can send me a complete copy of this article with pictures!

Another article:

Diagnostic Flow Chart that mentions the "Quick Take Up" M/C. under "1.2: DETERMINE TYPE OF HYDRAULIC SYSF :

I really think our cars are supposed to have the Export JM4 Non-U.S. ABS MC which is very specific to 90-92 Broughams: Delco# 18M420 (made by Raybestos for Delco and re-boxed according to Raybestos under the DuraStop label which is the same as Raybestos #MC39764 28.6mm/40mm step bore 2 piston design) or original Delco short# 174-657 (mfg.?).

I just wonder what the difference is. Or could it be the same part, but with different part#'s for Cadillac vs. the GM Trucks? :hmm:

Someone who originally cataloged these part #'s from GM messed up the whole aftermarket. I'm looking into buying an orig. parts book unless someone here can look up the orig. part number in a hard copy GM Caddy parts book.

Who knows, maybe the M/C we have is a Quick Take Up M/C..........and if you changed your calipers and the aftermarket no longer makes the low drag calipers, the system is still missmatched now with the wrong calipers!!!!!!!!!!!!

07-15-13, 01:16 AM
It's not a hard copy, but GM wiki has almost all every GM parts catalog, from 1952-1993. Most of them deal with Chevrolet, but you might be able to cross reference the part numbers you have; the master cylinder your looking for was Cadillac exclusive, so if you find your part numbers in the Chevrolet catalog, you know you don't have the right one.


Here's a page taken from the 1991 Chevrolet Light Truck Catalog:


07-15-13, 02:22 AM
Thanks "sven914".

What exact part number did you use for Rockauto. I tried many times and could not find it but found it as a internet search referencing the casting number for a specific brake booster as seen here under the "PRIOR" Booster:
http://www.rockauto.com/catalog/raframecatalog.php?carcode=1050860&parttype=1884&a=www.google.com%2BSearch%2Bfor%2B1991%2BCHEVROLET %2BK1500%2BPICKUP%2B4.3L%2BV6%2BBrake%252FWheel%2B Hub%2BPower%2BBrake%2BBooster&ck[ID]=0&ck[idlist]=0&ck[viewcurrency]=USD&ck[PHP_SESSION_ID]=nt72vqn1qin66c4sph820q4gb5

Yes, I did see that on the Delco site which I thought was a little vague especially since the dealer was going by all of the option info in their database like Export, Except U.S. with ABS and from their database and the Delco Distributor, it appeared that the U.S. models did not have ABS unless they were designated for Export, but decided to keep the options here. They made it really confusing but the Delco site simplifies it which makes me wonder. Maybe it's not a Quick Take Up M/C because like Raybestos told me that they'd be surprised if those calipers were still being made with that specific groove in the piston. In addition, that Delco 18M420 is the "DuraStop" label reboxed by Raybestos for Delco.

I need to talk with an engineer at Raybestos because the one tech knew what was going on and put me on this stupid scavenger hunt.......

As far as the wipers, did you ever try to adjust the transmission?

Also, when the glass is wet, can you put your wipers on high, then shut the key off when they reach next to the "A" pillar. Does the bend in the upper wiper keep the blade perfectly parallel to the "A" pillar?

If not, that's where I think the problem exists and no matter how the wiper transmission is adjusted, it can never keep the blade parallel with the "A" pillar. Which I believe the wiper arm is aftermarket and bent incorrectly. Another issue I'll have to look into.

I know of an orig. owner of a low millage 1992 Brougham somewhat personally, but terms are questionable. Not sure if he'll allow me to look at this stuff which would really solve my problems!!!!!!!!!

I'm in an apt. building and that car parks 20 feet behind mine! Neighborhood politics.......:kick: :rant2: :bricks:


WOW.......I never saw that site before! Thanks again "sven914".





According to the Caddy Dealer, using my VIN the orig. part# is #18016093 which supersedes to #18030662 which states "Exc. US w/ anti-lock" then gives the Delco #18M420 and Delco short# 174-657.


07-15-13, 03:38 AM
I searched 18016429 on Google, and found the Prior cylinder you just mentioned. I also searched under your year and model, and Rock Auto came up with the Delco 18M420 as used exclusively on '90-'92 Broughams with Anti-lock, except ones built for the US market.

Here is another good site: http://www.lov2xlr8.no/broch1.html

They have brochures for a lot of different cars. They don't have one for the '91 Brougham, but they do have one for '92 and the ABS braking system is not listed among the available options. You're probably right that ABS was an export only feature, and the master cylinder was specific to that option. If a car was ordered for an international buyer, and the sale fell through, the car would be sold domestically but none of the international add-ons would be removed.

When I was in automotive training, my school had a few international-edition cars donated, because the manufacturer couldn't find a buyer.


I've never tried adjusting the transmission on my wipers. Next time it rains here, I'll check to see if the blade is parallel to the A-pillar.

07-15-13, 03:57 AM
Thanks SVEN914,

I do see the 92' had ABS Bosch III on pg. 54, 55 and 56 under Chassis/Engine and Brakes for the 5.0 like I have.




Hard to read, but zoom in and its there.......

I really think all 90-92 Broughams had ABS and the parts listing info was an error creating this fiasco....

07-15-13, 10:09 AM
Skirts are from www.fenderskirts.us in CA. 951-928-0073.
Your discussion on brakes leaves me with a dumb? question: If 'newer' wheel cyls were redesigned to not have the Quick take up feature, then what would be the harm of using the master cyl that had such a feature since no Quick take up would now be needed? Afraid I tend toward old school and may not even be keeping up with your discussion. Thanks for the references though, I may need them someday.

07-15-13, 02:41 PM
Thanks SVEN914,

I do see the 92' had ABS Bosch III on pg. 54, 55 and 56 under Chassis/Engine and Brakes for the 5.0 like I have.




Hard to read, but zoom in and its there.......

I really think all 90-92 Broughams had ABS and the parts listing info was an error creating this fiasco....

Okay, I didn't see that and forgot that Broughams had ABS after '89.

The RPO might be different for the standard system. The JM4 RPO is "BRAKE, SYSTEM, PWR, FRT DISC, RR DRUM, CAST IRON." It doesn't mention anything about ABS.

Here are some sites that list GM RPO codes:

http://www.angelfire.com/ny2/96transam/rpocodes.html: Intended to decode the '96 Trans Am; has GM RPO codes dating back to the 1980's

http://aplsweb.com/Topics/TopicPix/RPO.pdf: Updated GM RPO Master list; some codes have been resigned to newer models

I don't know the code the Bosch ABS system, but if you can find a car that has one and look at the RPO label, the braking system would be a J-code.

07-15-13, 07:58 PM
Interesting now that I've read several of the refs. Sven 914's description for JM4 is what NAPA lists for two of their rebuilt M/C's :

Brake Master Cylinder - Remfd
Part Number: P3108
Product Line: Proformer Master Cylinders
IMPORTANT INFO: GM Code JM4 (Front Disc or Rear Drum Power System, Cast Iron);Option Codes are Located on the "GM Service Parts Identification" Sticker;w/ Reservoir
RESERVE & PICKUP $ 56.80 /ea

I thought mine was aluminum and went and checked w/magnet. It is alum. The ref to cast iron is apparently for something else. The Cad Service Manual calls for alum. M/c's.

07-15-13, 08:46 PM
I think cast iron refers to the rear drums

07-15-13, 09:08 PM
Cast iron refers to the reservoir. Later ones have plastic reservoirs. I would guess that they are just using a common GM core and reman'ing it to the OE specs (bore size/stroke/pedal and booster connection/output line connections)