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TR7 Brakes

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TR7 Brakes
#1
  This topic is about my 1980 Triumph TR7
Lagodude Avatar
Lagodude Garry Bayer
Lago Vista, TX, USA   USA
Hey guys,
Hope this is the last issue to get the old girl road worth.
Please excuse the repost of the same issue, can't seem to find the old post. I've had this ongoing brake issue since the beginning.
I'm hoping to stick with the stock brakes on the TR7, but understand they have their issues.
I have replaced all brake components.
-Brake Servo (standard the Rimmer upgraded)
- Master (twice)
- front calipers
- pads
- rear cylinders
- shoes
I've also replaced the Proportional Valve with no luck and someone suggested I try the Wedge Shop block to eliminate the P Value.
We have bled the system for hours with no air bubbles in system.
Have the seem issue.
I will try to explain where we are at:
The car is on jack stands and all wheels are off the ground.
I have bench bled the master.
I can push down on the peddle and about half way down hit a stop (clunk), at that point I have rear solid (good) rear brakes, but front wheels still will turn (with some resistance).
Pump brakes again (as I would when bleeding) and peddle stops before half way (clunk) and have solid rear brake and better (not great) front brakes.
Pump one more time (3 total) (stops a little higher yet) and have all four wheels stopping perfectly.
It sounds like there is still air bubble in system, but we have none.
Has anyone else had this brake scenario?
How do I resolve this issue, so I can get her on the road?
As always your help is greatly appreciated,
Thanks,
GarryB

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FrankieD Frank D'Angelo
King George, VA, USA   USA
Have you replaced the brake hoses? If they are expanding, and absorbing the pressure, you may not be getting all the pressure the system is putting out, being applied to the front brakes. Sorry, if this is a repeat suggestion from before.

Lagodude Avatar
Lagodude Garry Bayer
Lago Vista, TX, USA   USA
Hi Frank,
Thanks for the insight. I failed to mention that all brake hoses have been replaced.
Appreciate the reply,
GarryB

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Mr. Nuts Avatar
Mr. Nuts Peter N
Tucumcari, NM, USA   USA
Your brake pedal should not be stopping with a clunk half way down. What is the "(standard the Rimmer upgraded)"? Sounds like you have a miss-match of parts. With the brake lines disconnected at the proportional valve does the pedal go all the way to the floor? It should. I'd fix that first. It sounds to me like one of the rods is too long, either the pedal rod or the servo rod.

Do you get fluid coming out of the front and rear ports on the master cylinder with the lines disconnected at the proportional valve? You have a couple issues going on at the same time. I'd work through them one at a time.

A lot of people call every change an "upgrade". I think there are vey few real upgrades, the rest is just hype for the consumer or BS. There's no need for an upgraded servo on otherwise stock TR7 brakes. The servo is not the limiting factor.

Good luck with your project.

Pat.L Avatar
Pat.L Silver Member Patrick Ledford
New Wilmington, PA, USA   USA
In reply to # 1589387 by Lagodude Hey guys,
Hope this is the last issue to get the old girl road worth.
Please excuse the repost of the same issue, can't seem to find the old post. I've had this ongoing brake issue since the beginning.
I'm hoping to stick with the stock brakes on the TR7, but understand they have their issues.
I have replaced all brake components.

You may have done this but I found out the bleeding of brakes is a little different than American cars. In other cars you start at the furthest wheel cylinder at the rear in the Wedge you start at the furthest caliper in the front. Also you need to remove the brake failure plug under the M/C. Attached is the description from the TR8 ROM but should be the same for a TR7.

BRAKES Bleed 70.25.02 Do not allow the fuel level in the reservoir to fall below half capacity. When topping-up during the bleeding process, DO NOT USE aerated fluid exhausted from the system. DO NOT bleed the system with the servo in operation (engine running). 1 Disconnect the wires to the pressure failure switch and remove the pressure failure switch from the underside of the master cylinder. 2 Release the hand brake. 3 Attach the bleed tube to the bleed nipple of the front caliper farthest from the master cylinder, allowing the free end of the bleed tube to hang submerged in brake fluid in a transparent container. 4 Open the bleed nipple (90 to 180 degrees). 5 Fully depress the brake pedal and follow with three rapid successive strokes. Allow the pedal to return. Repeat this procedure until fluid free from air bubbles issues from the wheel cylinder. 6 Depress the brake pedal, close the nipple and release the pedal. 7 Remove the bleed tube. 8 Attach the bleed tube to the opposite front caliper and repeat instructions 4 to 7. 9 Attach the bleed tube to the single nipple on the rear backplate (R.H. Stg. - left-hand backplate; L.H. Stg. right-hand backplate) and repeat instructions 4 to 7. 10 Fit the pressure failure switch to the master cylinder and connect the wires. The P.D.W.A. shuttle fitted to this vehicle is self-centring.



Patrick
1980 TR8 DHC TPVDV8AT209637
1957 TR-3 Under restoration TS20462LO
Western Pennsylvania Triumph Association
TWOA

Lagodude Avatar
Lagodude Garry Bayer
Lago Vista, TX, USA   USA
Hi Peter,

The car had set for 10+ years. I am completely restoring. I replaced all brake parts.

I replaced the servo with the Uprated unit at the suggestion from Rimmer Tech Support rather than the std unit:

https://rimmerbros.com/Item--i-RB7656

I will be reinstalling the Proportional value and rebleeding system today.

Appreciate your help,

GarryB

Lagodude Avatar
Lagodude Garry Bayer
Lago Vista, TX, USA   USA
Hi Patrick,

I will be bleeding system again today. I will use your suggested bleeding method.

Thanks for your help,

GarryB

sliproc Avatar
sliproc Kevin Quistberg E
Long Beach, CA, USA   USA
Garry,

When you replace so many components you're essentially starting with a dry system, it's possible to trap a really big air bubble in one of these components that won't pass during a normal bleed, that's why bench bleeding is sometimes called for. I'd look for anywhere a new component could trap air above the brake line.

old guy Avatar
old guy bob k
sparta, tn., USA   USA
I know this sounds to simple but is it possible that the front brake line is swapped with the rear line ? It is normal for the front brakes to engage first then the rear, and yours are sounding as that may be the case. My car also sat for a very long time (20 years) so I understand the problems you can have on that "perfect car".

Darth V8R Avatar
Darth V8R Vance Navarrette
Beaverton, OR, USA   USA
1980 Triumph TR7 Drophead "The Great Pumpkin"
1980 Triumph TR8 "Wedgie"
In reply to # 1589387 by Lagodude Hey guys,

I've also replaced the Proportional Valve with no luck and someone suggested I try the Wedge Shop block to eliminate the P Value.

How do I resolve this issue, so I can get her on the road?
As always your help is greatly appreciated,
Thanks,
GarryB

Garry:

Was the replacement proportioning valve new or used?

I ask because they have a characteristic failure mode, and if the replacement was used, it probably is suffering the same problem.

I replaced the valve in the TR8 with a new Land Rover proportioning valve with very good results.

Alternately you can rebuild the valve with good results. I did this on my previous TR7, and I had rebuilt the TR8 valve as well, but the threads pulled out of it during reinstallation, and heli-coiling is not an option on those things. Heli-coils will not adequately seal the threads, and repair is impossible in a shallow blind hole.

The TR8 proportioning valve was full of something that looked like cooked oatmeal.

Your symptoms sure sound like a bad proportioning valve to me.

Vance



1980 Platinum Metallic TR8, frame off restoration, complete.
1980 Vermilion TR7 Sprint replica, in progress.

Lagodude Avatar
Lagodude Garry Bayer
Lago Vista, TX, USA   USA
Hey Kevin,

Understand your point. All components were not replace at same time but in a normal sequence. I have bench bled each component as it was installed.

Thanks for your suggestion,

GarryB

Lagodude Avatar
Lagodude Garry Bayer
Lago Vista, TX, USA   USA
Hi Bob,

I thought about that very thing a while back in the process. Through this restoration I've found a few things that have been messed with in the past. But, looking at pictures in the manuals, the lines are hooked up correctly. But, your observation sounds like a logical conclusion. I will try inverting the lines from the master to the P valve if nothing else works.

Appreciate your suggestion.

Thanks,

GarryB

Lagodude Avatar
Lagodude Garry Bayer
Lago Vista, TX, USA   USA
Hi Vance,

Appreciate your input to my girls brake problem.

The replacement valve was new from Rimmer. But, your analogy sounds like a possibility.

Can you give the Land Rover part number to the valve you used?

At this point I'm looking for resolutions.

Your help and experience is appreciated.

Thanks buddy,

GarryB

Darth V8R Avatar
Darth V8R Vance Navarrette
Beaverton, OR, USA   USA
1980 Triumph TR7 Drophead "The Great Pumpkin"
1980 Triumph TR8 "Wedgie"
In reply to # 1589670 by Lagodude Hi Vance,


Can you give the Land Rover part number to the valve you used?

At this point I'm looking for resolutions.

Your help and experience is appreciated.

Thanks buddy,

GarryB

Garry:

If the proportioning valve was new, I don't think that is the place to be looking. While components can be bad right out of the box, I think it is unlikely. The LR part number was ANR3194. But if Rimmer is supplying new valves, I would stick with their part.

Next question: It is possible to assemble the automatic brake adjusters backwards for the rear brakes. Did you get the brake adjusters assembled correctly, and have you made certain the brakes have self adjusted so that the slack is out of the rear brakes?

I have attached a photo from a thread elsewhere on this forum showing the correct orientation of the adjusters. This is not mentioned in the ROM, and is often done incorrectly.

Vance



1980 Platinum Metallic TR8, frame off restoration, complete.
1980 Vermilion TR7 Sprint replica, in progress.


Attachments:
20140717_120830.jpg    52.7 KB
20140717_120830.jpg

Lagodude Avatar
Lagodude Garry Bayer
Lago Vista, TX, USA   USA
Hi Guys,

Thank you all for the great advise and input.

She is back on the road and the brakes are acceptable.

I will be bleeding them again soon, using Patrick's method.

Appreciate y'all,

GarryB

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