TR4/4A Difficulty Level with specific maintenance TR4 - Part 2

[scottkilpatrick]

Hi all, thanks to all the input on my previous thread regarding brake addressing on my 62 TR4 recently acquired with no maintenance records. The brake pedal seems to sink rather low, there is squeaking in one of the wheels, and just general inconsistent feel in the pedal when I press and let off.


So I am in education mode and hope to tackle the brake system in a few weeks over Thanksgiving.


My question is does it matter on what I do first?


I plan on rebuilding the master cylinder for brakes using the Moss rebuild kit, and assume it should be ok as long as the inner shaft the piston is in is smooth and not gouged in any way. Or would it be suggested to replace it?


Secondly I plan on replacing the brake shoes or pads (can’t figure out which the TR4 uses or if its the same thing) for each wheel.


I don’t believe the TR4 has any such brake booster.


Does it matter what I do first? Master Cylinder or brake shoes?


Thanks everyone

 

[Sarastro]

It doesn't matter, but have you checked the brakes to be sure they need to be replaced? It sounds like you haven't. My own suggestion is to observe the old saying: if it ain't broke, don't fix it.

Also, be sure to do a little reading in the shop manual. Working on brakes isn't difficult, but it's kinda important to get it right. So, get a good mental picture of what you will be doing before you start.

 

[scottkilpatrick]

Thanks Sarastro, yes i have the haynes and the triumph work manual plus you tube. I am in full education mode currently to avoid problems. But yes they are squeaking and the pedal upon pressing goes down pretty far like its losing pressure and when i let up it starts over...that seems like it could be the master cylinder and the squeaking the brake shoes. Thats my guess

 

[mctriumph]

I differ with sarastro on this ,cherry out the entire braking system first thing.
Safety is nothing to guess at since it will be YOU in the ER.
Do it right, do it once, you wont be sorry.
Mad dog

 

[Popeye]

Brakes are critical; the TR4 has a single brake circuit (and no booster). There is no backup (half brakes) if something breaks.

It might make sense to clean everything really well (fittings, connections, under the master cylinder, inside the rear drums, etc.). Then apply firm pressure to the pedal and see if you have fluid loss anywhere. A dry white paper towel tucked under a connection shows moisture well. A long clamp can be used between seat and pedal to apply pressure to the brake pedal, as you crawl around to to find any leaks.

I’m the kinda guy who replaces anything that’s questionable quality and safety related. I rebuilt my front calipers (using the better stainless pistons from TRF), installed new rear cylinders, replaced the brake lines, and installed a new master cylinder. Not terribly difficult, but probably set me back $500-1000. Brake lines were the most expensive bit; I used stainless pre-bent lines from Classic Tube. I could have saved quite a bit if I bent my own from a roll of tubing.

Bleeding is a bit of a pain, mainly because you have to do it a few times if using DOT-5, see below, not to mention every time a leak is found and fixed (I try hard not to over-torque connections, but in the end some needed a bit more oomph). I use a Gunson pressurized bleeder. I use DOT-5 to prevent paint damage (and happy I did it as I addressed small leaks!) - but (1) you probably do not want to change fluid type unless replacing all the components, and (2) there are differing opinions on whether -5 is the way to go: brake pedal feel, ability to de-gas small bubbles, hydroscopic nature, paint removal, etc.

 

[Popeye]

If you decide to replace the rear brake cylinders, read this page: > wheel cyl install <

(And order extra spring plates to have on hand… they get mangled easy.)

 

[bobhustead]

On rebuilding the master- There is no such thing as 'good enough' in honing nicks and gouges out of the cylinder body. It needs to be perfectly smooth for the rubber on the piston to seal to the cylinder walls. If you have to hone it too far, again the rubber on the piston will not properly engage the cylinder walls and you will still have bleed down or no pedal at all. Unless you are dedicated to originality, it is easier and provides a more certain result to simply replace the cylinder and skip the rebuild. There are also folks who can sleeve the cylinder so you don't need to hone.
I recommend DOT5 brake fluid, mostly for paint issues, and it is not hydroscopic. I recall that your last thread indicated that the brake pedal was creeping slowly down when depressed. This is the classic first symptom of a bad master. Fix it first.
Bob

 

[TR4nut]

Long time but now ex-owner of a few TR4s. I’m with the fix it completely crowd. There are still good new master cylinders available and reasonably priced. I would buy new. You could always save the old one for later and potentially resleeve it but I would only do that if it were an original part and you are trying to create a concours stock car. Likewise good quality wheel cylinders are available and I’d change them out as part of the rebuild

 

[Sarastro]

Thanks Sarastro, yes i have the haynes and the triumph work manual plus you tube. I am in full education mode currently to avoid problems. But yes they are squeaking and the pedal upon pressing goes down pretty far like its losing pressure and when i let up it starts over...that seems like it could be the master cylinder and the squeaking the brake shoes. Thats my guess

You really don't know their condition until you inspect them. The squeaking likely is just the shoes rubbing on the backing plate. A little brake grease will fix that easily.