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#1 |
Registered User
Join Date: May 2011
Location: Goliad, TX
Posts: 672
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Need more braking force
The braking is kind of weak on my 1990 3/4 ton 4x4 Suburban I believe. It's got vacuum assisted brakes. I can stand on the brakes with both feet and it still doesn't have enough clamping force to skid. When hauling a load, it becomes much worse.
1. Is this normal? 2. Is there a way to increase clamping force such as installing a different master cylinder. If the master cylinder had a smaller bore, it would give more clamping force. 3. Could it be that I've got the wrong master cylinder on the vehicle? Thanks.......
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1990 ¾ ton 4x4 Chevy Suburban -Cummins Diesel - 12 valve - factory rebuilt -6 speed bullet proof manual transmission - NV5600 -Gear Vendors Overdrive - HX35 Holset Turbo -NP205 iron transfer case -3.73 gears -2" Lift |
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#2 |
Registered User
Join Date: Jun 2010
Location: Pittsburg, KS
Posts: 953
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Re: Need more braking force
I see that you have a cummins in the truck. Diesels don't put out enough vacumm and I'm sure the vacumm pump does not put out enough vacumm either. You would upgrade to a hydroboost system. Mine would make my crew cab slide on pavement.
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1980 K10 - 6.2L Diesel/SM465/NP205 Build Thread 1984 K30 CC Dually - "The Tank" 12V Cummins/Nv4500/Np205/D60/D70HD 4" lift & 37's Build Thread 1960 C-60 Dump Truck Make it road worthy! Thread |
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#3 |
Slots go on anything!
Join Date: May 2003
Location: Richardson, TX
Posts: 5,957
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Re: Need more braking force
Do you have a vacuum pump? Swtiching to a hydroboost setup may help if not. I thought most GM trucks originally equipped with a diesel was so equipped.
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1974 Jimmy- 5.3/4L80e/NP241 |
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#4 |
BAD BOW-Silverado XST
Join Date: May 2000
Location: Senior Member from Austin, TX
Posts: 6,431
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Re: Need more braking force
Wow, that's a lot of power and weight to stop. Do you have a 14 bolt rear end? It's time to upgrade it to disc brakes.
Hydroboost is probably the best upgrade. |
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#5 |
Registered User
Join Date: May 2011
Location: Goliad, TX
Posts: 672
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Re: Need more braking force
Yes, the Cummins has a vacuum pump and there is plenty of vacuum there. The engine in fact came out of a truck that had vacuum assisted brakes.
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1990 ¾ ton 4x4 Chevy Suburban -Cummins Diesel - 12 valve - factory rebuilt -6 speed bullet proof manual transmission - NV5600 -Gear Vendors Overdrive - HX35 Holset Turbo -NP205 iron transfer case -3.73 gears -2" Lift |
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#6 |
Registered User
Join Date: Jun 2010
Location: Pittsburg, KS
Posts: 953
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Re: Need more braking force
I would really suggest hydroboost. Most 1 ton trucks came with it. It can be expensive to first put on the truck, but after you do it I am sure it will make a big difference.
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1980 K10 - 6.2L Diesel/SM465/NP205 Build Thread 1984 K30 CC Dually - "The Tank" 12V Cummins/Nv4500/Np205/D60/D70HD 4" lift & 37's Build Thread 1960 C-60 Dump Truck Make it road worthy! Thread |
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#7 | |
Registered User
Join Date: May 2011
Location: Goliad, TX
Posts: 672
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Re: Need more braking force
Quote:
My 1982 1/2 ton Suburban has the hydroboost setup and it has a lot more clamping force even with the much smaller brakes. I would have thought a 3/4 braking system would be even more effective than that.
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1990 ¾ ton 4x4 Chevy Suburban -Cummins Diesel - 12 valve - factory rebuilt -6 speed bullet proof manual transmission - NV5600 -Gear Vendors Overdrive - HX35 Holset Turbo -NP205 iron transfer case -3.73 gears -2" Lift |
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#8 |
Registered User
Join Date: May 2011
Location: Goliad, TX
Posts: 672
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Re: Need more braking force
Shouldn't vacuum assist brakes be able to put as much clamping force as a hydroboost setup? Both setups are just force multipliers. I'm really wondering if maybe I might have an incorrect master cylinder on the truck.
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1990 ¾ ton 4x4 Chevy Suburban -Cummins Diesel - 12 valve - factory rebuilt -6 speed bullet proof manual transmission - NV5600 -Gear Vendors Overdrive - HX35 Holset Turbo -NP205 iron transfer case -3.73 gears -2" Lift Last edited by Edahall; 07-09-2012 at 04:30 PM. |
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#9 | ||
Registered User
Join Date: Jun 2010
Location: Pittsburg, KS
Posts: 953
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Re: Need more braking force
Quote:
Quote:
Posted via Mobile Device
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1980 K10 - 6.2L Diesel/SM465/NP205 Build Thread 1984 K30 CC Dually - "The Tank" 12V Cummins/Nv4500/Np205/D60/D70HD 4" lift & 37's Build Thread 1960 C-60 Dump Truck Make it road worthy! Thread |
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#10 |
Registered User
Join Date: May 2011
Location: Goliad, TX
Posts: 672
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Re: Need more braking force
I thought 3/4 ton trucks have 12.5" rotors and 1/2 ton trucks have 11.86" rotors.
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1990 ¾ ton 4x4 Chevy Suburban -Cummins Diesel - 12 valve - factory rebuilt -6 speed bullet proof manual transmission - NV5600 -Gear Vendors Overdrive - HX35 Holset Turbo -NP205 iron transfer case -3.73 gears -2" Lift |
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#11 |
Registered User
Join Date: Jun 2010
Location: Pittsburg, KS
Posts: 953
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Re: Need more braking force
Ok you are right they do use a bigger rotor and I guess the calipers are different as well. I just know basically all the outer parts except for the brakes is the same expect for the hubs being 6 or 8 lug. My 12 bolt 6 lug and d44 8 lug all used the same ujoints, shafts, spindels, and knuckles, so I assumed the brakes where the same my bad. I still think hydroboost would really help tho. All diesel equipped Chevys came with thr hydroboost because the vacuum pump wouldn't handle the brake system that well. Are you sure you are getting good vacumm? Maybe your brake booster is going bad?
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1980 K10 - 6.2L Diesel/SM465/NP205 Build Thread 1984 K30 CC Dually - "The Tank" 12V Cummins/Nv4500/Np205/D60/D70HD 4" lift & 37's Build Thread 1960 C-60 Dump Truck Make it road worthy! Thread Last edited by Mattman2010; 07-09-2012 at 05:23 PM. |
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#12 | |
Registered User
Join Date: May 2011
Location: Goliad, TX
Posts: 672
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Re: Need more braking force
Quote:
Bad brake booster? Well that's a possibility. Is there a way to test it and if so, how do I test it?
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1990 ¾ ton 4x4 Chevy Suburban -Cummins Diesel - 12 valve - factory rebuilt -6 speed bullet proof manual transmission - NV5600 -Gear Vendors Overdrive - HX35 Holset Turbo -NP205 iron transfer case -3.73 gears -2" Lift |
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#13 |
Registered User
Join Date: Jul 2009
Location: washington
Posts: 4,178
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Re: Need more braking force
Try ss braided lines. I got some for my 1/2 ton abd i have hardly any vacuume and they just about turned my brakes to normal
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#14 |
Registered User
Join Date: Jun 2010
Location: Pittsburg, KS
Posts: 953
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Re: Need more braking force
I really don't know the answer to that question. I've never had a bad one so I'm not sure how to test if it is bad or not
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1980 K10 - 6.2L Diesel/SM465/NP205 Build Thread 1984 K30 CC Dually - "The Tank" 12V Cummins/Nv4500/Np205/D60/D70HD 4" lift & 37's Build Thread 1960 C-60 Dump Truck Make it road worthy! Thread |
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#15 |
Registered User
Join Date: May 2009
Location: Motor City
Posts: 9,180
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Re: Need more braking force
Here are the brake system release charts for an '87 V20 Suburban:
![]() This would show you what your truck would have come with originally, in terms of master cylinder and wheel cylinder sizes, proportioning valves, etc, by part number. Here are some other charts, in case you want to do some "shopping" and see if there is another system you might like better: http://67-72chevytrucks.com/vboard/s...d.php?t=510519
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#16 | |
Registered User
Join Date: May 2011
Location: Goliad, TX
Posts: 672
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Re: Need more braking force
Quote:
http://www.ehow.com/how-does_4829365...-boosters.html |
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#17 | |
Registered User
Join Date: May 2011
Location: Goliad, TX
Posts: 672
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Re: Need more braking force
Quote:
Thanks a lot. This is exactly what I needed. As I suspected, there are master cylinders with different bores for my truck. My truck happens to be the heavy duty 8600 GVWR. It looks like if I install a master cylinder off a lighter duty 6600 GVWR (which has a smaller bore), it'll increase the pedal ratio and increase clamping force. ![]()
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1990 ¾ ton 4x4 Chevy Suburban -Cummins Diesel - 12 valve - factory rebuilt -6 speed bullet proof manual transmission - NV5600 -Gear Vendors Overdrive - HX35 Holset Turbo -NP205 iron transfer case -3.73 gears -2" Lift |
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