Sprint cluch master union sizes?

[GrahamFountain]

I'm looking for a replacement master cylinder for the clutch on my Sprint, and need to know the inlet and outlet union thread sizes.

The problem I have is about an inch of travel on the pedal between the slack in the clevis pin being taken up (which is already 3/4" after I start pressing) and there being any resistance from the master. Between the two, the clutch is only just disengaged by the time the pedal hits the bulkhead. If there's two layers of carpet down there, I can't get reverse without a load of grinding. So, I'm hoping at least some of that is wear in the master, the fork on the pedal end of the pushrod, and the clevis pin - it's probably one that nearly fits anyway - which a new cylinder will fix all of. Even if that only fixes most of the excess travel, that will be good.

Alun thinks this Wilwood one looks about right http://www.wilwood.com/Images/MasterCyl ... dwg-lg.jpg, but wasn't certain about the thread sizes. These are about £35 on eBay and the forks to thread on the pushrod are about £6.

Graham

[Galileo]

I might have missed the point, but the standard one's outlet is 7/16 UNF.

Think I'm in the same boat, new clutch and the bite is just off the floor with lots of initial travel at the pedal end, sometimes it travels further than normal. It's not a worn clevis pin, pushrod or air bubbles either. I've recently changed the master cylinder seals due to some minor leaking, and can't say that the bore was that bad, but maybe it has gained a taper with use? Either way, it's got to go.

I've got one of these on the shelf, was going to be the front circuit of my kit car's (I'm never going to build) floor mounted pedal set. Either change the hose, or buy a 7/16 to 3/8 adaptor would work.

http://www.carbuildersolutions.com/uk/0 ... -reservoir
http://www.carbuildersolutions.com/uk/5 ... der-clevis

Edit: Bad HTML coding

[sprint95m]

Wilwood cylinders are sold in modular form,
so one cylinder is made in each bore size,
the different union options are accommodated using adapters.

You will need a 3/8"UNF to 7/16"UNF adapter…..which one depends on your hose's union type (gender).




Ian.

PS TDC members get a 10% discount from Car Builder Solutions.

[Jon Tilson]

If your master hold pressure it isn't "worn" and a new one may well make zero difference.

It may have a broken or weak spring so the piston isn't coming all the way back, but I find that pretty rare.

Excess travel before biting is sometimes caused by a damaged or broken wedgelock in the bearing carrier fork or a broken weld
on the cross shaft lever. Look for these before pulling cylinders. The clue is the cross shaft lever going too far and contacting the
box casing.

Jonners

[GrahamFountain]

If your master hold pressure it isn't "worn" and a new one may well make zero difference.

It may have a broken or weak spring so the piston isn't coming all the way back, but I find that pretty rare.

Excess travel before biting is sometimes caused by a damaged or broken wedgelock in the bearing carrier fork or a broken weld
on the cross shaft lever. Look for these before pulling cylinders. The clue is the cross shaft lever going too far and contacting the
box casing.

Jonners

Jonners,

I don't think it's any hydrailic parts of the master that're at fault; rather, I think it's some mechanical issue. I think that there is a lot of movment of the master cylender pushrod that is doing nothing, and not moving any part of the cylinder internals. Hence, I think the broken/weak spring sounds very possible. If it is something like that, I think I'd like to replace the cylinder and look at the old one at leasure.

The garage that put a new clutch in as part of the engine swap reckon there's naught wrong at the cluch end, hydraulic or mechanical. I'm haviing somone else look at doing the master and putting a braded hose in at the same time. I don't think the hose is the culpret, but I once had the clutch bite point disappear off to the other side of the bulkhead when it all got a bit hot - I hate driving with no clutch. But it's not happened again, so I've had the goodrich in the boot for ages. Anyway, I'll get them to look at the issue with the wedgelock and the cross shaft lever at the same time. Got any pictures I can show them?

Graham

[Galileo]

Allow me:

Where the cross shaft snaps:


Broken wedgelock / taper bolt:


And the location of the taper bolt:


PS. I know it's not my taper bolt, just put a brand new one in!

[GrahamFountain]

Thanks for the pics.
There's no cracks or dicernable play in the the lever? The feel in the master's pushrod is of entirely free movment - there'd be some resistance even if it was only moving the two pistons and the fluid between, and that would feel different from free play. So I still think it's a gap between where the spring on the pedal arm pulls the pushrod out to and where the piston's comming back to.

So, if I get the Wilwood one, I need a 7/16 to 3/8 UNF adaptor (and a 5/16th screw-on fork). Is that a male-male or male-female adaptor?

Graham

[Jon Tilson]

A cheaper way ahead would be to whip of your clutch master and take the end boot and pushrod off. If you see the piston down the bore you know the spring isn't doing a good enough job. If the piston pops out and you push it down and it pops back again you know its fine and the problem is eslewhere.

You can replace the piston, spring and whatever else comes out with one from any Girling 5/8 bore master. These are fitted to loads
of cars like ordinary dolomites, spits etc and may even still be available new.

Jonners

[xvivalve]

I've had a broken cylinder spring previously, but in my case the primary symptom was fluid loss as the broken end of the spring had scored the bore. This was back in the heady days when there was an independent motor factor on every high street, all of which carried new cylinders...

[GrahamFountain]

[quote="Jon Tilson"]You can replace the piston, spring and whatever else comes out with one from any Girling 5/8 bore master. [quote]

Can't seem to see any that suit and are worth paying that much for on eBay. And I have to have this done by a garage. So I still think it's best done as a stiaght replacement with the Wilwood or sim.

So, what kind of adaptor will I need to get if I'm fitting a goodrich braded hose and the existing resevoir feed to the Wilwood cylinder in the above drawing?

[sprint95m]

Your Goodrich hose has a 7/16"UNF female union…?
You will therefore need a 3/8"UNF male to 7/16"UNF male adapter,
for example
http://www.carbuildersolutions.com/uk/i ... 8-unf-male



Ian.

[xvivalve]

Or get a custom goodrich hose made and no adaptor necessary...

[GrahamFountain]

Your Goodrich hose has a 7/16"UNF female union…?

It will be the same as the ones Rimers sell, though not got from them.

But I've also found a Girling 5/8ths master with a resevoir in the garage - got it with a dizzy I bought on line. I'm still not sure whether to pull the old one and give it a try with the bits from this, or just by a new one, and the adaptor and adjustable fork, and have it as a straight swapover. If I didn't want the car for transport, life would be so much easier.

Graham

[Jon Tilson]

The innards of both will be pretty much identical if both are Girling OE.

As long as the piston moves freely and pops out against the circlip under its own spring it will be what you want.

When I rebuild them I use a bit of red rubber grease so they stay free for a good while in storage.

Jonners

[GrahamFountain]

Jonners,

The one in the garage appears to be old but unused, so I hope its innards are good. Is is likely the pushrods will be the same length?
I'm kind of wondering if this will fit without a connection to a remote reservoir, pro-temps, and look for another, or get one of the 12 quid Chinese ones (here mid July – early August) to see if the spring, etc, will swap. I can at least check the goodridge hose against the outlet.

Graham