Capri Booster upgrade info

[andrewed1]

Hi all,

i am looking for some thoughts or guidance. I have upgrade my brake only to find there is allot of travel and not allot of braking power.

Car = Capri Gt Mk1

running:
STD capri booster & M/C

disc / drum

Disc = vented (approx. 10 or 12")

calipers = RX7


As i do not have alot of braking power and alot of travel, i have been thinking of changing the booster/MC.

This car has been storred for the last few years, and now going to rego it as a daily driver. if i upgrade or change the booster/mc combo does this need and engineers cert.? the car will need a blue slip for rego.

The wife say drive it or sell it, so the option is drive it. of course.

please any ideas or combos appricated

Thanks

Andrew.

[muzzy]

Hi andrew
Brake pedal travel has nothing to do with set up rather is an issue of
1 Air in system
2 Pedal adjustment to booster
3 Drum brake adjustment
my question
can you pump the pedal and get a higher pedal?
if you can then the problem is air or brake adjustment

As to stopping power, If the rx7 calipers are bigger in piston size then standard the vehicle, it should over brake, if they are smaller then it will under brake,
Rotors glazed, wrong pads, combination valve seized. I would suggest sort the brake out rather then change, I own a capri when they were new and brakes were fine, time takes it toll on all of us.
Muzza

[andrewed1]

Muzzy,

Thanks for the suggestions, I beleive there is no air in the system, been blead to many times to increase the braking.

You mention "Pedal adjustment to booster" how is this adjusted ? (could be the simple answer..)

I do the believe the main reason stopping is insufficient is because i increased the wheel size to 15", (from std 13") this is why the calipers & disk where upgraded. Now the brake's just do not stop good enough (takes too long to pull up) and i am looking for alternative's.

I've heard that a 120y Datsun Booster will Fit a XC master cylinder or a RangeRover Defender M/C should fit the 2.0l Pinto Capri booster. Both these M/C are 1" rather than the std 5/8" Capri.

or i have been thinking about FORD XW-XB booster &m/c as the Castlemain Rod shop does a convertor KIt for theses and is it possible to installe this booster without to much trouble?

Thanks

Please inform me if what i am saying is incorrect or sound wrong or close, and please point me in the correct direction.

[muzzy]

Originally Posted by andrewed1

Muzzy,

You mention "Pedal adjustment to booster" how is this adjusted ? (could be the simple answer..)

Adjustable rod between pedal and booster.

I do the believe the main reason stopping is insufficient is because i increased the wheel size to 15", (from std 13") this is why the calipers & disk where upgraded. Now the brake's just do not stop good enough (takes too long to pull up) and i am looking for alternative's.

I've heard that a 120y Datsun Booster will Fit a XC master cylinder or a RangeRover Defender M/C should fit the 2.0l Pinto Capri booster. Both these M/C are 1" rather than the std 5/8" Capri.

Could be good ideas the best way is to look at the sizes
F= PxA is the formula
so an increase in Booster would would result in more pressure to the master cyl ( your foot (force in N) x A of booster= High pressure to M'Cyl

Increase in master cyl, would result in greater force needed to operate, required to stop ( think of a bottle jack)
so a bigger booster and bigger m'cyl would cancel each other out.

i would find out all the sizes as standard, look at whats done and work it out from there.

or i have been thinking about FORD XW-XB booster &m/c as the Castlemain Rod shop does a convertor KIt for theses and is it possible to installe this booster without to much trouble?

Thanks

Please inform me if what i am saying is incorrect or sound wrong or close, and please point me in the correct direction.

Answer in RED

[andrewed1]

Muzza,

thanks for your information this will be very usefull. I will keep you posted with results.

[ClevoCapri]

Pedal travel has everything to do with putting bigger calipers on the front. The larger the size of caliper pistons over standard will increase the movement required by the brake pedal to move the larger pistons onto the disk with the same force. Only way to fix it is to go a bigger master cyl. Atleast 1 inch.

TC-TE gemini boosters fit. They are smaller and twin diaphram so provide greater boosting and take up less room. You will need to modify the pedal to booster pushrod but this isnt hard. You cant fit an xb master to these. Youd be better off putting the xb master onto a std booster.

I have std master cyl on a gemini booster. Tralvel of the pedal is longer but still works ok. Front calipers are hz on xe disk with xd drum rear. Aproved by an engineer.

You could always call a place like hoppers stoppers. They do some nice brake upgrades for capri's.

Hope that helps.

[allanv6gt]

ClevoCapri is (first para) referring to the fluid capacity in the system. Larger diameter caliper pistons need more fluid to move the same distance than smaller diameter pistons. It's all about relationship between master and slave cylinder capacities.
And if adjusting the input shaft into the master cylinder from the booster, there are precise measurements. Even a few mm makes a huge difference.

[ClevoCapri]

Yes thats right. With a small caliper piston you would have less pedal travel but a higher pedal force required for a given braking force. So a larger caliper piston will require more pedal travel for the same braking force. But less pedal force is required.
I hope that makes sence????

The adjustment with the booster Im talking about was pedal to booster. For the gemini booster fitment. But yes adjusting the rod between booster and master cyl does need to be fairly acurate to avoid master cyl not releasing fully or booster "hitting" master cyl on aplication.

[andrewed1]

thank you both the the above information, very useful.

sound like you both have had alot of experience. with my current brake setup any suggestion on Booster and M/C setup? please also advised any modifications need to istall/fit.

Car = Capri Gt Mk1

running:
STD capri booster & M/C

Disc / Drum
Disc = vented (approx. 10 or 12")
Drum = Std.
calipers = Mazda FC RX7, series 4/5

[allanv6gt]

Sorry can't help with specifics.
Contact one of the specialist upgrade businesses or a brake shop who have done conversions.
Some meaningful maths is involved to find the answer.

This is one of the reasons to stick with standard components, or buy a complete upgrade kit where someone else has already worked out what goes with what.

And all my experience is just with sorting out the jumble of boxes of bits (some of which didn't belong) to put it all together.

[ClevoCapri]

Depends what you use the car for.
A xb master cyl will fit std booster with only mods to the pushrod between booster and master. That will help your pedal travel issue. You may need to fit a brake bias valve. Which may or may not be an option for you.
Your best bet would be to call hoppers stoppers and get a complete upgrade from them.

I have, gemini booster, std master cyl.
xe disks and hz caliper. Xd drums on the rear. It works fine for normal street use and stopping down the drags but if I was doing some track work/sprints.
I would be upgrading master cyl and front disks and calipers.

[WOGBOY69]

hi all

i sort i have the same problem .

but i thought cause i had a bigger cam it was taking to much from my peddal .
and i was going to get like a air tank and a small pump eletric pump to pump air into the booster . if you all know what iam talking about .
does that solve the break peddal at all

cheers

gerry

[andrewed1]

Though my research i have found that if you have increased your cam (which i also have) this will also reduce the manifold vacuum which the brake booster uses. this should also be above 18" of pressure.

You could also make a PVC Vacuum Reservoir to store the vacuum pressure.

sample of the link i found:
http://www.summet.com/blog/2011/03/2...uum-reservoir/

I have not yet completed this though am going to try.

[XRQTR]

Before you spend any money give this a go:

Take off your master from the booster and turn the actuator pin inwards until it's sitting at about the same point as the seat on the master (I'd take pics but mines at the engineers atm), replace master and bleed system.

Start at the closest, yes closest, so drivers side front wheel, push once and release fluid, do this about half a dozen times or until no air. Don't worry about pumping coz you'll also need to get the old oil out, make sure you keep an eye on the reservoir as this will empty it quicker. Move on to the left front, do the same with one full compression per fluid release, then do the rear.

Once you've finished flushing and removing air take the master off again and this time adjust the pin outwards, only 3-4 full turns to start with then check the brakes. If this doesn't fix it then try another 3-4 turns, you should start to feel a difference in braking pretty quickly.

Even though I'm running the original V6 brakes I was always told the lack of vacuum (big cam 302) was causing my braking issues, I even went out and bought a vac pump. Anyway I just thought one time I'd try playing with the actuator rod and sure enough fixed it.

I'm not saying that this will for sure fix your problem but if it does then it could save you a few bucks, so worth trying.

[XRQTR]

Also with regard to rego, I'd hurry coz the rules are about to change soon, that's why mines at the engineers now. You could always go club reg under the new 90 day set up but I want full street reg.

[allanv6gt]

IF playing with kength of actuator rod (adjustment), don't go too far. It will cause the disc brakes to jam on.
I know this, as the 'rebuilt' master cylinder piston extended further outside the cylinder casing than the old one, thereby decreasing correct movement settings.

[WOGBOY69]

ooooooooooo.... . .now iam confussed big time...

[XRQTR]

Originally Posted by allanv6gt

the 'rebuilt' master cylinder piston extended further outside the cylinder casing than the old one, thereby decreasing correct movement settings.

That's what I thought, even when I looked at it when it came back, ooooohhh a couple of years ago LOL it looked quite different.

I'm only suggesting this because I was told by all the specialists that I'd need to upgrade and that there was no other way, so I figured nothing to lose if it didn't work. Anyway it has worked and the few times that she's been driven now has caused no issues.

Although I was getting brake lock in the rear end prior to the rebuild when the actuator rod was extended outwards, I'd tried the rod adjustment before rebuilding the master but had the master rebuilt because of the rears locking up whenever the rod was wound out but then not having enough braking when it was wound back.

The brakes are working quite well now after you put a little heat in the linings, but even when cold are still 4-5 times better than previously.

[allanv6gt]

...after 500m around the block (the first metres travelled in 20yrs mind) the fronts were just starting to smoke.
The manual has some very precise measurements about how fat the actuating rod needs to sit *below* the mating surface on booster for master cylinder. Measurements which go out the window if the m/c cylinder is not 5+mm proud of where it was before 'professional rebuild' (and that cylinder is still sitting on the bench awaiting autopsy).

[allanv6gt]

not how 'fat'...just how far LOL
I'm trying to lose weight, not very successfully .....he he he

[XRQTR]

Originally Posted by allanv6gt

I'm trying to lose weight, not very successfully .....he he he

You and me both, don't worry, I've actually put about 6 kg on in the last 3 months.

What I found strange was that after fitting the reco'd master the pedal feel was atrocious, it actually felt firmer prior to the rebuild, but because we hadn't played with the rod when bleeding the system after the initial refit I just wanted to eliminate it.

In the last few days I've driven it to Thomastown and back I live in Deer Park so about a 30 km trip one way on the freeway and no problems whatsoever. I will admit that I haven't rebuilt the front calipers but now that it's all working well I can put that off for now.

As I said it may not work for everyone but it's worth a shot and it may well save you a few bucks.

[WOGBOY69]

Hi All

Well after just checking my presure of pounds for the booster on my ford capri v6. i have on idel on around 15 pounds and of caurse when reving the car it goes around 20 to 22 pounds . does that sound right to anyone or is it to big of a cam and i need a compresor to pump more air
if anyone has got more info it would be great

cheers

wogboy

[XRQTR]

You should be measuring vacuum not pressure, I was told anything above 10inches mercury was necessary but mine is around 8, and yes idle should be fine to measure from.

Using a Vac guage remove the vac hose from the booster and attach it to the guage, should give you a reading straight away.

[WOGBOY69]

hi all

yep sorry about that,,,,, vacuum .not pounds your right on that ... but still i think iam low in the numbers

cheers

gerry

[XRQTR]

Like I said mines at 8 inches (hg not errrmmm) and mine stop fine for standard brakes.

[WOGBOY69]

yes mine stops good as well but it feals more of a manual brake pedal then. well i suppose iam comparing it to new cars how they brake today standerd..

cheers

[XRQTR]

Ye common mistake, I did the same as well, best is to drive it around for a little while to get used to the brakes. These days because of ABS we can push hard and it stops pretty quick without locking (mostly), but the older brakes do take some getting used to.

My opinion and I'm sure some would agree while others would disagree, however having driven both it's about right. Even my old Zs brakes were similar to what these are now. I just use the auto to slow down a little quicker.