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TR2/3/3A Brake Restrictor valve?

karls59tr

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I'v read the arcived posts on the restrictor valve and I see that some have removed it with no bad consequences. Is it possible for that restrictor to get so gummed up after 60 years that it could cause a front caliper to seize? Reason I ask is I had the left front wheel lock up on me a couple years ago and I don't think it was a too tight or loose spindle nut. Is it possible that a partially blocked restrictor would seize a caliper under cerain conditions ie hard driving?
 

Snowkilts

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Is it possible that your caliper pistons seized? They can get very rusty. Stainless steel replacements are available.

I would think that for the restrictor to seize it would have to have something solid in the line downstream of the valve that would act as a one-way valve, allowing fluid to pass when you step on the brake but not return. Seems unlikely, but I suppose anything is possible.
 
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karls59tr

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Is it possible that your caliper pistons seized? They can get very rusty. Stainless steel replacements are available.

I would think that for the restrictor to seize it would have to have something solid in the line downstream of the valve that would act as a one-way valve, allowing fluid to pass when you step on the brake but not return. Seems unlikely, but I suppose anything is possible.
I had rebuilt the calipers so the pistons were good. I did some research and found that more than a few TR3 drivers have removed the guts from the valve and replaced the restrictor. Apparently Triumph did away with the restrictor for the TR4 and I see that they are now N/A at Moss.
 

Geo Hahn

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What's in there (in case you need to know):

restrictor valve.JPG


Looks like I gutted it 19 years ago.

Remember: 'The first rule of tinkering is save all the parts' [Aldo Leopold]
 

CJD

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If it were the restrictor...both front wheels would have seized. I think you are looking for another problem.

If you remove the restrictor, then you will notice that if you drive for several miles without using the brakes...especially on twisting roads...the first application of the brakes will go to the floorboard. A quick pump will get it back, so if you are ready for it, it's no big deal. If you let someone else drive it and the brakes go to the floor they will probably never borrow the car again!
 
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karls59tr

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It is possible that both sides did lock up but only on the drivers side did the hub, rotor and brake caliper suffer damage. When I wrestled the car over to the side of the road I looked underneath and there was a grease fire at both calipers which I put out by throwing gravel dust on the flames. Front left wheel was tilted inwards. I've always thought the cause was a too loose spindle nut but now I'm thinking the restrictor valve may have played a part in the incident. I just read where TR3 driver gutted his restrictor valve and noticed very little difference in pedal travel.
 
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karls59tr

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The rubber brake hose can collapse inside and act as a one way valve. I had this on a Daimler sp250 it cooked the pads disc/rotor and boiled the fluid.
new rubber brake lines to the front sorted the issue.
I can see that happening alright. Thing is I have the braided steel lines. Do you run the restrictor valve on your race car? When you are racing a TR3 and you dive into a corner I've heard that there can be so much flex that the brake pedal can go to the floor but I think there is an upgraded spindle kit for that issue. Do you suppose a restrictor could get gummed up over the years and lock the brakes on only under certain circumstances and perform normally most of the time? What would happen if the internal spring failed?
 

CJD

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If the fluid in your system is "gummed up" enough to cause a problem with the restrictor, I think the caliper piston sticking would be more of a problem than the restrictor.
 

Hamish Racing

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I can see that happening alright. Thing is I have the braided steel lines. Do you run the restrictor valve on your race car? When you are racing a TR3 and you dive into a corner I've heard that there can be so much flex that the brake pedal can go to the floor but I think there is an upgraded spindle kit for that issue. Do you suppose a restrictor could get gummed up over the years and lock the brakes on only under certain circumstances and perform normally most of the time? What would happen if the internal spring failed?

I don’t have the restrictor plain solid pipe work down to the splitter with the brake light switch and on around the car and steel braid for the flexi pipes. Standard discs and nos ferodo pads. I can lock the front with the stickyest of race tyres they are good brakes.
I have never had stub axle flex affect the brakes. But I did worry about their age and strength especially with the added stress of the very sticky tyres- I really lean on them - I’ll try and post pictures separately. This I have fitted an uprated hub kit.

 
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