82 hj47 brake question

[82HJ47]

I replaced these valves with new parts and failed to note which goes where Does anyone know which valve shown below is for the front brake and which for the rear brake on a brake master cylinder? Drums are standard front and rear on my vehicle.



I replaced both the above with new ones shown below which both have an integral built in valve. I now seem to be easily locking up my rear brakes which was not the case before I replaced these valves!



The workshop manual shows both as having the small sprung valve as shown in pic 2, but that's not what was fitted when removed - see pic 1.



Thanks in anticipation

 

[Bear]

My parts manual shows the correct part number for BOTH front and rear check valves for the HJ47 years 8/1980 - 4/1986 to be 47280-30030.

Several possibilities:
Your parts guy may have chosen an incorrect part for you.
Or this may be the correct part with a superceded number.
Or you may have the incorrect master cylinder for your vehicle.

Suggestion, before you go back to the dealership:
Try removing one of the inner valves and replacing it on the master cylinder in either front or rear location--then give it a test drive.

There were quite a few different check valves used on Land Cruisers over the years.
this may simply be the wrong replacement.

Good luck.

 

[82HJ47]

Thanks Bear,

I did question the parts guy when I ordered them and he said 47280‑14010 was a replacement for 47280‑30030. They are identical in every way besides my removed one not having the check valve in place in one of the valves.

My master is OEM so I believe has no bearing on the matter.

Here's what the parts manual says, note the 47280 and 47290 as well as the description with 42790 specifically saying "for rear side". This seems to suggest something......

Possibly the word "CHECK" in 47280 has the little sprung valve with no mention of "CHECK" in 47290 suggesting it's without.....I may just have answered my own question here

47280 VALVE ASSY, BRAKE MASTER CYLINDER OUTLET CHECK- 47280‑30030
47290 VALVE ASSY, MASTER CYLINDER OUTLET (FOR REAR SIDE) - 47280‑30030

See also the exploded part which backs the description up.

http://farm9.staticflickr.com/8363/8337199832_c38cdf2fab.jpg

Toyota cannot answer my query, most if not ALL the guys who worked on these vehicles in the 70s & '80's have moved on. The new mechanics have no idea as they only work on the modern LC's. I did speak with one chap at some point who possibly thought the front brake had the little sprung valve and the rear did not.....but he was not 100% sure.

It's a PITA to swap these out and test as suggested because everything needs to be bled again etc etc so I was hoping someone would know what's what

 

[Bear]

Peter,

I'm not clear why you replaced these valves in the first place. Were you having a brake problem before the switch?
I am also not clear what other brake parts you replaced before the "problem" appeared.


There are MANY different master cylinders that MAY interchange with the factory original ones--some are top-loaders, and some are side-loaders. Some later models will retrofit onto an earlier vehicle, some will not. If yours is truly factory original to your vehicle, if no one has ever tampered with your brake system since it was delivered from the factory, and if the parts you purchased have been superceded by the factory, then they should work correctly in the original intended application.

The new check valves appear to be the same as ONE of the originals you have.
The original valve without the exposed check valve appears to have a clear-through orifice.
Is it possible that there may have been a visible check valve inside this valve that possibly broke off and has fallen into the mastercylinder? A visual inspection of your original photos looks like the spring and check-valve has fallen out of, or been plucked out of, the second valve you show. Could it have fallen out when you removed it? Could a small piece of plastic have become lodged inside the master cylinder?

Assuming you have not tampered with any other parts of the brake system before this occurrence, you have several options. You do have some work ahead of you to eliminate the possible causes:

If .......these two check valves are the ONLY parts you have replaced, and IF you didn't drop anything into the master cylinder, returning them to the master cylinder you have--in their original positions--should return your brake system to its original operation, once bled correctly. And my guess would be that the original clear-through check valve goes to the rear brake lines, and that is where I would initially test it. Be sure to completely bleed-out any small debris that may have come loose in the brake lines that might be impeding the operation of the rear brake cylinders.

You could go pull some used check valves off other vehicles like yours if you have a nearby salvage yard. In the process you can check if that vehicle has the same setup as you originally had--in other words, one of the valves is clear-through.

You could buy another master cylinder, complete with check valves, and try that--either a good used unit, or a new one.

 

[SOOT]

I replaced these valves with new parts and failed to note which goes where Does anyone know which valve shown below is for the front brake and which for the rear brake on a brake master cylinder? Drums are standard front and rear on my vehicle.

http://farm3.staticflickr.com/2656/3815120916_c7e09a936c.jpg

I replaced both the above with new ones shown below which both have an integral built in valve. I now seem to be easily locking up my rear brakes which was not the case before I replaced these valves!

http://farm3.staticflickr.com/2511/3818190188_178374f298.jpg

The workshop manual shows both as having the small sprung valve as shown in pic 2, but that's not what was fitted when removed - see pic 1.

http://farm3.staticflickr.com/2472/3814934123_d3b3b2ce99.jpg

Thanks in anticipation

You could try adjusting your rear drums to suit the new check valves that you have installed, maybe you are getting better pressure with the new ones. just an idea so you don't have to bleed the system again or try putting the old one with no check valve back in to see if it changes your braking.

Sent from my iPhone using IH8MUD

 

[82HJ47]

Bear & SOOT, thanks to you both for the food for thought, appreciated

@ Bear: The OEM Brake Master [I know OEM from aftermarket ] was leaking so I had it re-sleeved in s/steel with a new OEM service kit. I checked the OD bore size before the new kit was fitted so I know it was spot on. While I was there I replaced the valves for good measure...... I was having no brake issues before that other than the leaky master due to worn rubbers.

It's not possible there was a visible check valve in the removed valve that possibly may have fallen out. I would have seen this immediately, and of course a check valve of that size has zero chance of finding it's way into the MC....the orifice is just too small to allow something that 'big' to pass through it even if it had fallen out. I disassembled the MC on removal so I know there was nothing inside it other than what's supposed to be in there. You are correct in thinking possibly the check valve was "plucked" out as the one LC mechanic did suggest this is what they used to do, however he was not 100% sure it was for the front or back brake as it was 30 years since he worked on these "old" LC's.

I am of the opinion based on my last post and my discovery there based on the factory description of these valves 47280 & 47290 that it is the back brake that is without the visible "CHECK" valve and it's this route that I will pursue and see what results I get.

".......if you have a nearby salvage yard"
On this score I don't believe we are as fortunate as you back in the US of A

 

[RufusTheDufus]

Do you have drums front and rear or disk brakes? These valves are residual pressure valves. Disk brakes typically have either no valve or a 2 PSI residual pressure valve. Drums usually have a 10 PSI check valve.

If you have disk brakes up front do you know if this was the original stock configuration? Someone could have done a disk brake swap on the front which would mean stock part numbers for the master cylinder components wouldn't match up for you.

 

[82HJ47]

Drums are standard front and rear on my vehicle.

Rufus, and they still are. Never been got at, 100% OEM throughout.

Drums usually have a 10 PSI check valve.

Front or rear?

Thanks for the informative reply

 

[RufusTheDufus]

Both front and rear. The purpose of the valve is to hold the a little pressure against the mechanical return springs in a drum brake. Without the valve you would need to pump your brakes a few times to build up enough pressure for effective braking.

I don't think there's a difference in the check valve front vs. rear. They should be the same. Both front and rear drums need residual pressure valves. The balancing of pressure between front and rear is designed into the master cylinder. The fronts get slightly more pressure.

As a side note, I went disc brakes all around on my Troopy. The only change I made to the master cylinder was to pluck out the two check valves.

 

[82HJ47]

Again, some great informative info, thanks for that I'm just wondering if the held pressure due to the residual pressure valve is a reason for locking up my rear brakes I did a beautiful 360 James Bond pirouette type spin coming down a steep hill in the rain about a year back, happened so quick it didn't even scare me until it was over

 

[RufusTheDufus]

If your front brakes aren't doing much of anything because there's no check valve installed it's going to seem like your rear brakes are locking up when the reality is your rears are providing almost all of the braking force.

Maybe I misunderstood one or more of the posts above but it sounded like you didn't install the residual pressure valve in the front brakes. If that's the case you would need to pump the brakes two or three times for your fronts to start providing any significant braking force.

(Edited to add this) Did you install the new parts in the first post with the check valves in place? That's the part I'm not clear about.

 

[RufusTheDufus]

One more question: did you change your power brake booster when you had the MC off?

I ask because sometimes a mis-adjusted booster rod can exhibit the strange problems. There are lots of posts about it here on Mud. I wonder if the re-sleeve kit could have required a change in the adjuster rod length?

 

[82HJ47]

Did you install the new parts in the first post with the check valves in place? That's the part I'm not clear about.

Affirmative. The new check valves were installed as newly supplied as shown in the first post. What I removed was the used check valves in the first post and I was questioning whether the front or the rear brake had the check valve removed.

No, the booster was not replaced, only a new kit was fitted in the BMC