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TR6 ? about TR6 brakes

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crj7driver

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Are the front and rear brakes independent on the TR6. The reason I ask is I be will going to braided lines on the front. Will this be moot if I keep the rubber ones on the rear? Will the rear lines just expand that much more since there is no give on the front lines is my concern.

There are two reservoirs but only only one master cylinder (i.e one source of pressure) I think since this is the case the pressure will try to normalize throughout the system.

Just curious if someone knows definitively.

Thanks
 
Hi, you have two separate systems in the master and has two different internal pistons which give you brakes if one system fails. Your steel lines will give the front a bit more grab with the same pressure on the pedal, but the movement of the piston in the master will move the rears the same. You may want to adjust the rears one click tighter, if they are not rubbing at this time.

Wayne
 
Andrew Mace said:
with a tipping valve that (I believe; someone correct me if I'm wrong) helps to "shut off" a circuit with low pressure.
Click to expand...
It is two circuits, but the tipping valve is only the device that lets one of the chambers refill from the reservoir. (Can't use a foot valve like the other chamber does, because the other chamber is in the way.) The MC is arranged such that it applies equal pressure to both circuits until one of the MC pistons runs out of travel (allowing full pressure to be applied to the other circuit). Nothing ever "shuts off" a circuit except running out of fluid or similar complete failure.

Should be no problem with running SS lines in front and rubber in back. The slight difference in displacement should be well within the range the MC will accomodate.

But for the full benefit, you probably want to replace the rear lines as well. Since the MC balances the pressures, the ballooning of the soft lines will still increase pedal travel; by almost half as much as with rubber lines on all 4 corners.
 
Here's a diagram from Nelson, showing how the pressure from the front circuit (on the right) is what operates the secondary piston that pressurizes the rear brakes (on the left). You can also see the tipping valve above the primary piston, and the foot valve to the left of the secondary piston. Both valves are closed since this diagram is with the pedal depressed.

If the rear brakes lose pressure, the secondary piston hits bottom and the primary piston continues to supply pressure to the front brakes.

If the front brakes lose pressure, the primary piston hits the secondary piston, transmitting full pressure to the rear brakes.
 
<div class="ubbcode-block"><div class="ubbcode-header">Quote:]Since the MC balances the pressures, the ballooning of the soft lines will still increase pedal travel; by almost half as much as with rubber lines on all 4 corners.[/QUOTE]

Randall is correct. I have much less pedal travel with the SS reinforced lines on all four corners.
 
Wow, thanks for all the info, that is exactly what I was looking for. If could focus on any one thing I might get done with my project faster, but I seem to work on 5 things at once.
 
If it's any consolation, one of the Stags currently has SS braided on the front & rubber on the rear. Just haven't gotten around to updating the rears yet (along with shocks & bushings & all the other things I've got planned).
 
Huh, You say two reservoirs? As far as I know the 6 only came with ONE reservoir. It has a separator plate in it, but it is large somewhat rectangular. Are you thinking of the clutch reservoir as one?

I ran stainless on the front of one for about 6 months before I got around putting stainless on the rear. Unless you are heavy into autocrossing, slaloming or competition, I do not think you will feel much difference. Slightly firmer pedal with the stainless, but if your rubber hoses are in good shape, No problem..
 
That was my take on it. There is not 2 individual reservoirs, but it is chambered into two compartments. I don't believe they share any fluid with the exception of what might spill over the baffle but I don't have it sitting in front of me so I could be wrong.
 
Definitely one reservoir, with two chambers.

Don't have one in front of me to look at, but ISTR that the two chambers do share fluid while they are full. IOW the divider is lower than the normal fluid level, so that if you pour into one chamber it will fill the other chamber before either chamber comes up to the 'full' line.

But once the level falls below the divider, they are separate; no sharing of fluid.

The difference wasn't much, but I definitely noticed an improvement on the first Stag and TR3A with the braided lines. Of course both cars have been on the autocross track so YMMV.

BTW, I believe the spacers for the front spindles should also help reduce brake pedal travel, when driving hard. Haven't found a chance to try mine out yet, but I know that spindle flex is a real problem on a TR3A, and likely even worse on the heavier TR6.
 
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