xjbubba
NAXJA Member # 1524
- Location
- santa barbara, ca
Finally got tired of "pushing and praying" when trying to stop my '88 Cherokee.
Before this mod, my brake system consisted of '76 1/2-ton Chevy brakes forward and '86 Cad discs aft; both mounted on Dana 44's.
Moving up to larger calipers in the front, and adding discs in the rear necessitated increased master cylinder volume. Prior to my current mod, I was using a MC off of a Mercury Grand Marque that had hydro boost. That MC had a cylinder ID of 1.125, which was sufficient volume for my calipers; however, pedal pressure sucked, requiring the "push and pray" approach to braking.
I've been searching for some time for a "cohesive" wright-up regarding an upgrade to a dual-diaphragm booster AND an MC with a bore size of 1.125.
I settled on a 1.125 bore '03 Dodge Durango MC, and an 'o1 Cherokee booster (not Grand Cherokee).
I first ordered an received a WJ booster, as that was my first choice. Unfortunately, the Durango MC will not fit the WJ booster. The booster's front opening is 1/8 too small. I considered enlarging the whole, which would have been easy enough, but there is a large return spring just inside that hole that appears iffy as to fitting over the Durango's MC snout. Also, the MC mount pattern would also require ob-longing the MC's bolt holes. So I opted for the last year of XJ made--'01, mainly because at least one poster in another forum said the Durango MC fit without mods.
The WJ probably would be a better fit, because it does not angle up on the firewall like the '01 XJ does. Also, the booster rod to the brake pedal is similar length to the early XJ's. (My '88 rod is 4-15/16, while the WJ rod measured 5-1/4. So with a 1/4 spacer, the two boosters are basically the same distance from the brake pedal). However, the WJ booster requires bending the pinch seam on the firewall to clear the booster, even with the spacer in place.
The '01 XJ booster required no mods to the firewall (on my '88).
I couldn't take any pics (wife's away with the camera), but there are plenty of pics in other wright-ups to show all necessary details, except none are of an '01 booster being used. The following link, using an WJ booster, is farley close to my '01 install: http://naxja.org/forum/showthread.php?t=924285&highlight=booster+upgrade
Overall I'm very pleased with the results. My pedal is high (too high) and firm, but not hard. Two areas I need to address to meet my standards are (1) install an adjustable proportioning valve--the rears lock-up way to easy for safety.
And, (2), either modify the brake pedal arm, or shorten the booster rod an inch. The pedal now sets two inches higher than stock.
I don't like the idea of shortening the booster rod, because I'm afraid the heat from welding the cut rod back together will destroy internal seals. Also, in the event of booster failure, I'd need to modify any replacement, as well.
My second idea is to add a "bump" on the rear area of the brake pedal adjacent to the current booster-rod attachment hole, allowing me to re-drill the hole ~one inch rearward; this is probably what I'll do. I think that will lower the pedal with less trauma and work than modifying the booster rod.
Another difference I noticed between the WJ and the '01 XJ boosters, is the MC push rod is adjustable on the XJ but not on the WJ. Another reason to go with the XJ booster. I did have to adjust the rod out slightly to get the 1/16 clearance I was looking for between the MC and push rod.
I did use a home-made 1/4 spacer between the booster and the firewall. I also made two gaskets to seal out engine-bay smells and water.
As shown, and discussed in the wright-up I cited above , the '01 booster rod must be modified slightly to re-use the '88 brake light switch.
I drilled the '01 rod out to 5/8, then "honed" to fit the '88 XJ nylon bushing. I also ground a "flat" on the end of the rod to match the early rod. Light works like factory. Also, I was able to re-use the firewall to booster nuts from my '88.
The Durango MC bolted right up, using two 8m-1.25 nuts.
I ordered 3/16 by 40 inch brake tubing with bubble flares on both ends and 10mm-1.0 flare nuts. The MC uses 10mm-1.0 and 12mm-1.0 fittings.
I cut the tubing into two 15 inch sections, added SAE flare nuts to match my XJ's combo valve, and put a double flare on each of the two lines. I then used a welding rod cut to 15 inches to form my new lines.
Two areas of concern here: (1) my combo valve was too close to the booster for my rear line to properly align. To solve this, I was able to pull some "slack" out of the driver's side brake line, that runs to the front, left caliper. It didn't take much to give me the slack necessary to manipulate the combo valve into an acceptable position, allowing reasonable access to the rear fitting. I still need a 1/2 inch "flare" crows foot to properly torque the fitting; fortunately, I didn't experience any leaks!
Second (2), you need to keep the bends at the MC as tight as possible to allow the windshield washer bottle to fit. As it was, I had to move my reservoir forward ~one inch to clear the extra length of the booster. I also had to judiciously use a heat gun to "massage" my reservoir to clear the front tube running from the MC.
Good news, is all the electrical connectors reached their old "homes"; but I did have to extend the rubber tube ~4inches for the front mounted washer bottle pump.
Now a list of parts used, and their sources:
'01 Jeep Cherokee booster Cardone 54-73154 from Rockauto.com
'03 Dodge Durango MC Cardone 13-2967 from Rockauto.com
3/16 tubing x 40inches, with 10m-1.0 bubble flare fittings (only size available)
Steelhydraulics.com AA1142 (nuts were non-lead threaded, as required.)
12m-1.0 flare nuts, as well as extra 10m-1.0 flare nuts; both sizes with non-lead threads: M1-3 (10mm) and M6-3 (12mm) Fedhillusa.com
Nuts for MC to Booster 8m-1.25 my junk box
Nuts for mounting booster to firewall same ones used for my stock booster.
Hope I didn't forget anything important.
Be glad to answer questions, and would solicit comments on the install, and advice on lowering my pedal!
Cheers:confused1
Before this mod, my brake system consisted of '76 1/2-ton Chevy brakes forward and '86 Cad discs aft; both mounted on Dana 44's.
Moving up to larger calipers in the front, and adding discs in the rear necessitated increased master cylinder volume. Prior to my current mod, I was using a MC off of a Mercury Grand Marque that had hydro boost. That MC had a cylinder ID of 1.125, which was sufficient volume for my calipers; however, pedal pressure sucked, requiring the "push and pray" approach to braking.
I've been searching for some time for a "cohesive" wright-up regarding an upgrade to a dual-diaphragm booster AND an MC with a bore size of 1.125.
I settled on a 1.125 bore '03 Dodge Durango MC, and an 'o1 Cherokee booster (not Grand Cherokee).
I first ordered an received a WJ booster, as that was my first choice. Unfortunately, the Durango MC will not fit the WJ booster. The booster's front opening is 1/8 too small. I considered enlarging the whole, which would have been easy enough, but there is a large return spring just inside that hole that appears iffy as to fitting over the Durango's MC snout. Also, the MC mount pattern would also require ob-longing the MC's bolt holes. So I opted for the last year of XJ made--'01, mainly because at least one poster in another forum said the Durango MC fit without mods.
The WJ probably would be a better fit, because it does not angle up on the firewall like the '01 XJ does. Also, the booster rod to the brake pedal is similar length to the early XJ's. (My '88 rod is 4-15/16, while the WJ rod measured 5-1/4. So with a 1/4 spacer, the two boosters are basically the same distance from the brake pedal). However, the WJ booster requires bending the pinch seam on the firewall to clear the booster, even with the spacer in place.
The '01 XJ booster required no mods to the firewall (on my '88).
I couldn't take any pics (wife's away with the camera), but there are plenty of pics in other wright-ups to show all necessary details, except none are of an '01 booster being used. The following link, using an WJ booster, is farley close to my '01 install: http://naxja.org/forum/showthread.php?t=924285&highlight=booster+upgrade
Overall I'm very pleased with the results. My pedal is high (too high) and firm, but not hard. Two areas I need to address to meet my standards are (1) install an adjustable proportioning valve--the rears lock-up way to easy for safety.
And, (2), either modify the brake pedal arm, or shorten the booster rod an inch. The pedal now sets two inches higher than stock.
I don't like the idea of shortening the booster rod, because I'm afraid the heat from welding the cut rod back together will destroy internal seals. Also, in the event of booster failure, I'd need to modify any replacement, as well.
My second idea is to add a "bump" on the rear area of the brake pedal adjacent to the current booster-rod attachment hole, allowing me to re-drill the hole ~one inch rearward; this is probably what I'll do. I think that will lower the pedal with less trauma and work than modifying the booster rod.
Another difference I noticed between the WJ and the '01 XJ boosters, is the MC push rod is adjustable on the XJ but not on the WJ. Another reason to go with the XJ booster. I did have to adjust the rod out slightly to get the 1/16 clearance I was looking for between the MC and push rod.
I did use a home-made 1/4 spacer between the booster and the firewall. I also made two gaskets to seal out engine-bay smells and water.
As shown, and discussed in the wright-up I cited above , the '01 booster rod must be modified slightly to re-use the '88 brake light switch.
I drilled the '01 rod out to 5/8, then "honed" to fit the '88 XJ nylon bushing. I also ground a "flat" on the end of the rod to match the early rod. Light works like factory. Also, I was able to re-use the firewall to booster nuts from my '88.
The Durango MC bolted right up, using two 8m-1.25 nuts.
I ordered 3/16 by 40 inch brake tubing with bubble flares on both ends and 10mm-1.0 flare nuts. The MC uses 10mm-1.0 and 12mm-1.0 fittings.
I cut the tubing into two 15 inch sections, added SAE flare nuts to match my XJ's combo valve, and put a double flare on each of the two lines. I then used a welding rod cut to 15 inches to form my new lines.
Two areas of concern here: (1) my combo valve was too close to the booster for my rear line to properly align. To solve this, I was able to pull some "slack" out of the driver's side brake line, that runs to the front, left caliper. It didn't take much to give me the slack necessary to manipulate the combo valve into an acceptable position, allowing reasonable access to the rear fitting. I still need a 1/2 inch "flare" crows foot to properly torque the fitting; fortunately, I didn't experience any leaks!
Second (2), you need to keep the bends at the MC as tight as possible to allow the windshield washer bottle to fit. As it was, I had to move my reservoir forward ~one inch to clear the extra length of the booster. I also had to judiciously use a heat gun to "massage" my reservoir to clear the front tube running from the MC.
Good news, is all the electrical connectors reached their old "homes"; but I did have to extend the rubber tube ~4inches for the front mounted washer bottle pump.
Now a list of parts used, and their sources:
'01 Jeep Cherokee booster Cardone 54-73154 from Rockauto.com
'03 Dodge Durango MC Cardone 13-2967 from Rockauto.com
3/16 tubing x 40inches, with 10m-1.0 bubble flare fittings (only size available)
Steelhydraulics.com AA1142 (nuts were non-lead threaded, as required.)
12m-1.0 flare nuts, as well as extra 10m-1.0 flare nuts; both sizes with non-lead threads: M1-3 (10mm) and M6-3 (12mm) Fedhillusa.com
Nuts for MC to Booster 8m-1.25 my junk box
Nuts for mounting booster to firewall same ones used for my stock booster.
Hope I didn't forget anything important.
Be glad to answer questions, and would solicit comments on the install, and advice on lowering my pedal!
Cheers:confused1
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