Two or Three Reservoirs

**mlewis** · 01-25-2018, 08:30 PM

All,

I need to make some decisions around my hydraulic systems so I am looking for some input.

I'm installing the 12.88" Wilwood with the Wilwood pedal box. Also ordered a hydraulic clutch set-up from Mr Forte.

I would like to use individual reservoirs. Looking for some thoughts on whether I should have a separate reservoir for each system (i.e. 3) vs sharing a reservoir for the brake and a dedicated reservoir for the clutch (i.e. 2). What's the downside with the latter ?

Appreciate the input.

Mark

**phileas_fogg** · 01-25-2018, 09:17 PM

Go with three independent reservoirs (lots of folks like the CNC remote reservoir, part #1483).

The downside to sharing a reservoir between front and back brakes is that if you have a failure in the rear brakes your front brakes are taken out too (and vice versa). US automakers stopped using single reservoir brake systems BEFORE they started installing seat belts.

Cheers,

John

**qwezxc12** · 01-25-2018, 10:06 PM

I've got the 12.88in Wilwood brakes on my Coupe and a hydraulic clutch as well with the exception of using a hydraulic throwout bearing rather than a slave cylinder setup.

I also went with three independent reservoirs in a combined Tilton unit for safety. You can get one with push on fittings or -AN connectors from the reservoir to the master cylinders.

til-72-576.jpg

**mike forte** · 01-25-2018, 10:37 PM

Hi Mark,
I stock the dual or triple CNC reservoirs.

**mlewis** · 01-26-2018, 07:51 AM

Thanks all. I did consider the safety aspect (redundancy). I was leaning toward three independent reservoirs. Just looking for a nudge.

Mike - thanks for the heads up on your offering. I need to call you within the next couple of days (work schedule dependent), we can discuss then.

I do like the more vintage look though (i.e. separate canisters).

**MisterAdam** · 01-26-2018, 08:36 AM

is there a minimum size reservoir required for these brakes? i have the single reservoir and the unsafe aspect is always nagging in the back of my head. I will be "upgrading" in the spring but will have to cut an access panel into the top of the footbox first..uugghh.

**Avalanche325** · 01-26-2018, 10:25 AM

Dual brake reservoirs were mandated in 1967. Anything that goes on the road should have them.

The CNC ones are nice.

**qwezxc12** · 01-26-2018, 11:09 AM

Originally Posted by MisterAdam

is there a minimum size reservoir required for these brakes? i have the single reservoir and the unsafe aspect is always nagging in the back of my head. I will be "upgrading" in the spring but will have to cut an access panel into the top of the footbox first..uugghh.

I could not find any requirement per se, but here's my thoughts.

The Wilwood Remote Reservoir Master Cylinders come with the same two remote reservoir options if you were to buy them direct: 7oz (small) and 10 oz (large), so one could assume that anything in that capacity range should be fine.

The actual volume displacement for each of the MCs are quite small at full stroke:

3/4" MC, front 12.88" brakes, .48 cu in or .27 fl oz
5/8" MC, rear 12.88" brakes, .34 cu in or .18 fl oz
13/16" MC, clutch - as recommend by Tilton, .58 cu in or .32 fl oz

For reference, the Tilton combined 3-chamber reservoir has the following capacity:
9.8 oz front brakes
6.3 oz rear brakes
4.0 oz clutch

Here's an actual picture on an 8.5" x 11" sheet on my desk for scale:
20180126_104407.jpg

Hope that helps.

**Jim Schenck** · 01-26-2018, 11:47 AM

It isn't dual reservoirs that are required, most OEM cars have one reservoir that feeds the two separate sides of the master cylinder. What you have to have is separation between the two systems once the fluid is in the master cylinder so that a failure in one system allows you to still stop using the other end. Many of the OEM reservoirs have a divider on the bottom so that if the fluid level is very low and one side draws air (in case of a failure or leak) the other side will not. Having one reservoir with a tee and separate lines to each master also does this by having reserve in the line feeding each one. What you need is enough volume in the reservoir to maintain fluid as the brake pads wear down, and also more volume makes it easier to bleed the system.

**NAZ** · 01-26-2018, 01:23 PM

I concur with Jim. The Feds mandated dual M/C starting in 1968, not just the reservoirs but dual master cylinders. That way if you have a brake line or other component fail disabling one of the systems the other will still work. I've had such a failure on a single M/C system and had to use a hand brake to stop, but not before I blew through an intersection right behind cross traffic.

I prefer separate reservoirs either a common reservoir with a wall separating the front & back or individual reservoirs. That makes it so much easier to know when one system has a leak by simply looking at the individual fluid levels. As Jim stated, a larger reservoir makes bleeding easier as you don't have to keep such a close eye on the fluid level before topping it off. However, space constraints (or style) sometimes forces a compromise on this.

No matter if you choose a common reservoir or individuals the important thing is that the fluid be separated from the air. Brake fluid will absorb moisture out of the air and water in the brake fluid will lower the boiling point and can cause internal corrosion. I've seen some custom reservoirs vented directly to atmosphere and that's a problem. It would also be a problem if there is no vent. Look for a reservoir that has a diaphragm seal that separates the fluid from atmosphere and still allows the fluid to level to expand and contract without creating a vacuum.

**mlewis** · 01-28-2018, 05:22 PM

Hey all. Thanks for the feedback and guidance. I'm definitely going with 3 reservoirs

I like the new version from FFR. It's larger than the previous (8.16 oz vs 5.2oz volume). It now has a vent hole and gasket/diaphragm, You can see it on the new truck (I would attached a photo but seem to be having a problem doing so). Also like the new style bracket.

Mark

**GoDadGo** · 01-28-2018, 05:26 PM

Originally Posted by qwezxc12

I've got the 12.88in Wilwood brakes on my Coupe and a hydraulic clutch as well with the exception of using a hydraulic throwout bearing rather than a slave cylinder setup.

I also went with three independent reservoirs in a combined Tilton unit for safety. You can get one with push on fittings or -AN connectors from the reservoir to the master cylinders.

til-72-576.jpg

I've Got The Same Reservoir & It Works Fine!

https://www.summitracing.com/parts/til-72-576

You can see it 10-35 seconds in to the attached video:

https://youtu.be/PCngiKoopkA

Fits With The Theme Of My Build Which Is For Form To Follow Function!