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kp60 brake booster swap


hassan

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hi ,

my you help me to upgrade my kp60 starlet brake?

i have very hard brake and the mechanic told me change my brake booster but unfortunately i can't find the same booster in my country.

do any one know if i can swap it wiyh another brake booster and it will fit directlyin it ?

 

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11 hours ago, hassan said:

hi ,

my you help me to upgrade my kp60 starlet brake?

i have very hard brake and the mechanic told me change my brake booster but unfortunately i can't find the same booster in my country.

do any one know if i can swap it wiyh another brake booster and it will fit directlyin it ?

 

You could always try this if need be:

http://www.rockauto.com/en/catalog/toyota,1983,starlet,1.3l+l4,1278356,brake+&+wheel+hub,power+brake+booster,1884

 

Or else contact Darryn at http://oldscoolautos.co.nz . He'll have some laying around.

 

The boosters have an air filter on them and if this gets blocked then your brakes can get quite hard. What size are your wheels? When you get much bigger than the factory size the brakes get quite hard quite fast.

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8 hours ago, ajg193 said:

The boosters have an air filter on them and if this gets blocked then your brakes can get quite hard. What size are your wheels? When you get much bigger than the factory size the brakes get quite hard quite fast.

thanks alot for your help.

i'm using orginal stock wheel

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  • 3 weeks later...
23 minutes ago, BlownCorona said:

what

Big diameter tyre makes for longer lever arm between ground and centre of rotation. Brake diameter stays the same. Therefore brake force on ground reduces for same pedal effort. 

 

Ie 100 N at .1 m becomes 33 N at .3 m or 25 N at .4 m. a = F/m, so less deceleration for bigger wheel with same brake application 

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On 1/13/2018 at 07:54, ajg193 said:

You could always try this if need be:

http://www.rockauto.com/en/catalog/toyota,1983,starlet,1.3l+l4,1278356,brake+&+wheel+hub,power+brake+booster,1884

 

Or else contact Darryn at http://oldscoolautos.co.nz . He'll have some laying around.

 

The boosters have an air filter on them and if this gets blocked then your brakes can get quite hard. What size are your wheels? When you get much bigger than the factory size the brakes get quite hard quite fast.

No offense intended but I'll have to pull you up on your post. 

Mastervac boosters introduce the atmosphere (to the rear chamber of the vacuum suspended diaphragm)  from the cars interior.  Unless the OP's been carrying bulk cement mix in the floorwell for the last decade or so the blocked air filter diagnosis is very unlikely. 

Furthermore the rotating diameter of the wheels has little effect on the feel of the brake pedal, increasing the diameter lowers the caliper/pad leverage but also lowers the RPM/road speed ratio and vice-versa. Unless you're pushing the upper limits of brake heat dissipation and tyre adhesion for all intents and purposes nothing changes.

A hard pedal on a Mastervac booster is most likely caused by a lack of vacuum (faulty check valve or collapsed/blocked vacuum hose) or a ruptured diaphragm, in the case of the latter it's easy to spot as the engine will run as if it has a huge inlet vacuum leak. If the assistance has been progressively lessening there is also the chance that the reaction disc has deteriorated but that's an outside chance.

Re the OP's inquiry, a faulty mastervac is usually an easy to diagnosis with the right process. Send me a message and I can talk you through the process. Even better if you can make it to Milford (Auck-Nth Shore) rock round to the legendary sr2 man cave and we'll get you sorted.

 

Edited to say; you'll need to bring Beer!

 

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7 hours ago, sr2 said:

No offense intended but I'll have to pull you up on your post. 

Mastervac boosters introduce the atmosphere (to the rear chamber of the vacuum suspended diaphragm)  from the cars interior.  Unless the OP's been carrying bulk cement mix in the floorwell for the last decade or so the blocked air filter diagnosis is very unlikely. 

Furthermore the rotating diameter of the wheels has little effect on the feel of the brake pedal, increasing the diameter lowers the caliper/pad leverage but also lowers the RPM/road speed ratio and vice-versa. Unless you're pushing the upper limits of brake heat dissipation and tyre adhesion for all intents and purposes nothing changes.

A hard pedal on a Mastervac booster is most likely caused by a lack of vacuum (faulty check valve or collapsed/blocked vacuum hose) or a ruptured diaphragm, in the case of the latter it's easy to spot as the engine will run as if it has a huge inlet vacuum leak. If the assistance has been progressively lessening there is also the chance that the reaction disc has deteriorated but that's an outside chance.

Re the OP's inquiry, a faulty mastervac is usually an easy to diagnosis with the right process. Send me a message and I can talk you through the process. Even better if you can make it to Milford (Auck-Nth Shore) rock round to the legendary sr2 man cave and we'll get you sorted.

 

Edited to say; you'll need to bring Beer!

 

As far as I can tell he isn't in NZ, probably Egypt or Greece.

I'm just quoting the maintenance manual which recommends to replace the in cabin filters every 80,000 km.

I get what you mean though.

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7 hours ago, sr2 said:

 

Furthermore the rotating diameter of the wheels has little effect on the feel of the brake pedal, increasing the diameter lowers the caliper/pad leverage but also lowers the RPM/road speed ratio and vice-versa. Unless you're pushing the upper limits of brake heat dissipation and tyre adhesion for all intents and purposes nothing changes.

 


https://www.aamva.org/uploadedFiles/MainSite/Content/VehicleRegistrationTitling/vehStudyEffectOfOversizedTiresOnAlteredHeightVehicles_Findings.pdf

"The results of the tests indicated that oversize tires had a profound effect on rollover propensity and substantially increased the applied pedal forces required to achieve equivalent levels of braking performance."


Sure they needed substantial increase in tyre size to have a large effect, but if you go from 155/70R12 to 180/40R15 (or whatever) it will have an effect on the way the brakes feel.

This isn't his problem as he is running stock wheels.


There is a significant difference in brake pedal feel on a Starlet with the 155/70R12's compared to 175/70R13's on Sprint rims. There is a significant increase in brake pedal force required on the larger wheels, but the upside is that the car is a lot more stable under braking and seems less likely to lock an individual wheel.

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1 hour ago, ajg193 said:


https://www.aamva.org/uploadedFiles/MainSite/Content/VehicleRegistrationTitling/vehStudyEffectOfOversizedTiresOnAlteredHeightVehicles_Findings.pdf

"The results of the tests indicated that oversize tires had a profound effect on rollover propensity and substantially increased the applied pedal forces required to achieve equivalent levels of braking performance."

 

You possibly should have read the whole article? (Great link by the way).

"Although the disparity may have been due to slight differences in tire hardness and inflation pressures, the dissimilarity was more the result of contact being made between the front fenders and tires as the front fenders of the test vehicle pitched forward and dived downward during braking".

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I probably should read the whole article, yes.

Hmmm, looking at the article, the quote you give is with regards to the anomalous data for the 39.5" tyre - where they say that the shorter stopping distance for this tyre is due to the tyre rubbing the guard (extra braking force).

(I still haven't read the majority of the article)

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