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Master cylinder upgrade??
- Thread starter jgcable
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Jedi Trainee
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Welcome to the family - There's a post down a few in the Spridget forum title "60 sprite Clutch reservoir" that deals with this very issue and has a lot of excellent advice about how to and what must be done to change out - Of particular interest should be what the racers write since they always upgrade their systems to account for added power and such -
Have fun!
Bob M
Have fun!
Bob M
Thanks alot for the reply. I see that a 67 pedal box and master cylinder will work with some mods. The problem with using that set up for me is that it would cost the same as having my original master cylinder rebuilt unless I could find somebody parting out a 1967. Are there any other year pedal box's I could use?
Here are the problems I am experiencing with the rear brakes on my 1959 Bugeye. I have all new wheel cylinders, brake shoes, drums and hardware and the master cylinder has been rebuilt. I only use the brake side of the master cylinder because I have a chevy 4 spd in the car that doesn't require me using the clutch side.
If I shorten the master cylinder push rod my rear brakes work perfectly but my brake pedal will not stay pumped up. It will pump up fine but as soon as I release my foot from the pedal and push down again it goes to the floor and needs to be pumped up again.
If I lengthen the pushrod my brake pedal pumps up and stays right at the top but it is a very hard pedal and my rear brake cylinders expand and stay expanded causing my rear drums to lock up. The only way to get them to contract is to open up a bleeder.
I was told that if I am not using the clutch side of the master there needs to be a part installed in that side. Unfortunately I have no idea what that part is.
If I shorten the master cylinder push rod my rear brakes work perfectly but my brake pedal will not stay pumped up. It will pump up fine but as soon as I release my foot from the pedal and push down again it goes to the floor and needs to be pumped up again.
If I lengthen the pushrod my brake pedal pumps up and stays right at the top but it is a very hard pedal and my rear brake cylinders expand and stay expanded causing my rear drums to lock up. The only way to get them to contract is to open up a bleeder.
I was told that if I am not using the clutch side of the master there needs to be a part installed in that side. Unfortunately I have no idea what that part is.
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Jedi Trainee
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You said you have a Chevy 4 speed, Can I assume that you also have a chevy engine in place? If so if you are trying to utilize the stock braking system of the bug eye you are howling at the moon -
Extra horsepower+extra weight= Increased braking demand - I suggest at the very least you go to all wheel disk brakes - The little bugeye drum brakes weren't designed to stop a car with the added weight & power of a chevy mill - Ideally I would rethink the chevy powerplant, however sexy it may be -
Again, I assume that the front suspension has been beefed up or replaced with much heavier duty units? How about the little old differential back at the rear - Definitely not designed to take any more than about 90 horsepower, let alone the axleshaft which have a nasty habit of ringing off when subjected to a heavy right foot even with only the stock horsepower - Mines a 67 Sprite and it's packing a whopping 67 horsepower ( That what the specs say anyhow)
As for the rear brakes locking up - Check to see if the flexible hose that runs to the junction block bolted to the differential is in good shape - after years of exposure to brake fluid the inside of the hose can swell almost shut - It will let fluid through to the rear brakes under hydraulic pressure from the master cylinder but will not allow the pressure to release under the meager pressure exerted by the return springs of the back brakes. What you get is a sort of "Non-Release valve". Having to release pressure with the bleeder screw makes me think of that.
If your master cylinder bleeds down at all, under any circumstances theres only a couple things that can be happening - There is either air in the system, in which case the pedal will be spongey all the time, or The seals in the cylinder are shot and allows hydraulic pressure to leak down, particularly at stop lights, holding on a hill, etc. - I don't see how lengthening the push rod will make a difference.
The pedal box in you car will probably work - but you need to cut it out a bit as one other sprite guy noted in the last thread.
Lastly, If this car is set up correctly to handle a chevy engine, suspension, beefed up rear end, etc, it's obvious you've spent a quite a bit of money on it - Do yourself a favor, if you don't do another thing upgrade the braking system so it'll stop you effectively when it becomes necessay - as it always will, otherwise your relatives will be spending some of THEIR money separating you one last time from what remains of your Sprite.
I apologize if this seems like a gloomy prognosis, but if you read these threads there is one concept that is in just about any serious discussion of these nice little cars - The safer the car is the longer you'll live to enjoy it.
Hoping to hear from you for a long time to come - keep us posted.
Bob M.
Extra horsepower+extra weight= Increased braking demand - I suggest at the very least you go to all wheel disk brakes - The little bugeye drum brakes weren't designed to stop a car with the added weight & power of a chevy mill - Ideally I would rethink the chevy powerplant, however sexy it may be -
Again, I assume that the front suspension has been beefed up or replaced with much heavier duty units? How about the little old differential back at the rear - Definitely not designed to take any more than about 90 horsepower, let alone the axleshaft which have a nasty habit of ringing off when subjected to a heavy right foot even with only the stock horsepower - Mines a 67 Sprite and it's packing a whopping 67 horsepower ( That what the specs say anyhow)
As for the rear brakes locking up - Check to see if the flexible hose that runs to the junction block bolted to the differential is in good shape - after years of exposure to brake fluid the inside of the hose can swell almost shut - It will let fluid through to the rear brakes under hydraulic pressure from the master cylinder but will not allow the pressure to release under the meager pressure exerted by the return springs of the back brakes. What you get is a sort of "Non-Release valve". Having to release pressure with the bleeder screw makes me think of that.
If your master cylinder bleeds down at all, under any circumstances theres only a couple things that can be happening - There is either air in the system, in which case the pedal will be spongey all the time, or The seals in the cylinder are shot and allows hydraulic pressure to leak down, particularly at stop lights, holding on a hill, etc. - I don't see how lengthening the push rod will make a difference.
The pedal box in you car will probably work - but you need to cut it out a bit as one other sprite guy noted in the last thread.
Lastly, If this car is set up correctly to handle a chevy engine, suspension, beefed up rear end, etc, it's obvious you've spent a quite a bit of money on it - Do yourself a favor, if you don't do another thing upgrade the braking system so it'll stop you effectively when it becomes necessay - as it always will, otherwise your relatives will be spending some of THEIR money separating you one last time from what remains of your Sprite.
I apologize if this seems like a gloomy prognosis, but if you read these threads there is one concept that is in just about any serious discussion of these nice little cars - The safer the car is the longer you'll live to enjoy it.
Hoping to hear from you for a long time to come - keep us posted.
Bob M.
Again, thanks for the reply. The Chevy engine that is in it is a 2.3L 4 cylinder that was out of a 1971 Chevy Vega. It was rated at around 100hp stock but it has been ported/polished and bored 20 over. The block is aluminum. It is an extremely light motor. I am pretty sure it doesn't way much more than a stock motor. The entire suspension was upgraded. Unfortunately I have already sunk a ton of dough into the complete front end. Everything is new but unfortunately it is 4 wheel drum brakes. I installed racing brake shoes on it and it stops really good with just the front brakes. The rears have never worked right so i just left the drums off to take the car for a VERY short test ride. I know you guys probably frown on what I am about to say but I am not racing my car although it looks like it just came off of the track at Limerock. Once it is painted I will be applying full vintage race graphics. Most of the time I will be trailering it to vintage shows and events and occassionally driving it around town and to the local shows. Anyway.. I took the 14" flexible brake hose off of the rear brake line and cleaned it and blew air through it. It doesn't appear clogged at all. I reinstalled it and bled the brakes again and the same problem persists. Like I said.. if I lengthen the pushrod the brakes pump up fine and hold pressure but they will not release. If I shorten the pushrod the rear brakes work perfectly but they bleed down once I take my foot off of the brake pedal. Do you think the flexible rear cable with the T attached to it could still be the problem?
For about $15 bucks you can change the flexible brake hose. If it's not the problem you aren't out much. I am sometimes amazed at the numerous brake jobs on older cars including LBC's that change pads/shoes, wheel cylinders or caliper pistons, the master cylinder, rotors/drums and then leave in place brake hoses that are over 40 years old. From a safety point of view, it doesn't make sense.
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Jedi Trainee
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I agree with shorn - when doing brakes leave nothing to chance - a car that won't stop really sucks..
I lost my brakes a couple times before an old Sprite hand tipped me to the swollen brake hose gag - Plus blowing it out with a compressor may be misleading - the compressor may have enough gumption to blow through the hose, but the little return springs on the rear brakes may not have enough to back the shoes off.
Like shorn said - $15 isn't a lot of cash - Especially after all you've done - In for a Pence, In for a pound, eh?
I lost my brakes a couple times before an old Sprite hand tipped me to the swollen brake hose gag - Plus blowing it out with a compressor may be misleading - the compressor may have enough gumption to blow through the hose, but the little return springs on the rear brakes may not have enough to back the shoes off.
Like shorn said - $15 isn't a lot of cash - Especially after all you've done - In for a Pence, In for a pound, eh?
BRIAN TOWNE
Senior Member
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John, you indicated that your master had been rebuilt. Was it by chance sleeved? I had my master sleeved for my TR2 and the guy forgot to drill the bleed hole. I would pump my brakes, instant pressure but they would not bleed off. I have never looked at a Sprites master but if it was sleeved, might be worth looking into. Good luck
Brian
Brian
It was not sleeved. One person here mentioned to check the pushrod length because if it is too long it won't allow the piston to travel past the bleed hole to release the pressure. I rebuilt it but I am pretty sure it didn't need rebuilding. The bore was very clean and in great shape.