Brake Servo Removal

[Moose]

Has anybody actually removed a brake servo unit on a Series 3 without removing the brake master cylinder? Is it even possible? My servo seems to be kaput, I can hear the air leaking. I have a spare but I am no hurry to disturb the brake hydraulics as I know if I need to bleed the brakes, the nipples on the front cyl. will most likely be seized (been a while since they were touched).

I'm hoping that by undoing the master from the servo, the master my move forward enough if there is enough flex in the lines to allow the servo and brake peddle to be removed.

Anyone pulled this off before?

Brett

[NickDawson]

preface this with the caveat that Im as novice as they come...but...

I recently replaced my MC. I think you'll find that the MC is sealed b/t the piston (from the servo) and the unit itself. In other words, you'll have to take the MC off to replace or fix the servo but it will not require bleeding the brakes again.

You will need to be careful not to bend or reshape the brake lines too much, but you should have plenty of flexibility. I am assuming your Series III is a dual circuit (surprisingly mine was not, UK import). Once you remove the two bolts then the MC will pull away easily.

I have not replaced my servo yet, but need to - its dead. From the looks, it simply bolts to the firewall and has a vacuum line. The brake linkage attaches in the rear of the servo. It should be a straight forward swap.

Please keep us posted - lots of pics! (so I can follow when I do mine)

[greenmeanie]

Well looking at mine on the table here next to the computer in my parts storage room you'll need to move the master cylinder forward by about 1" to clear the mounting studs. THe servo to pedal box stud is about 1" too. The killer will be the link to the brake pedal itself which is approx. 3 1/2" inside the pedal box or about te center of the plastic cap on the side.

I won't say it can't be done because I have not tried but I will say it is unlikely.

[Moose]

Yeah, I figure (well, hope really) that once I undo the master and ease it forward a bit, the servo and peddle box could be removed complete. Separating the servo and peddle box can then be done in relative comfort on the bench as that step seems a little more awkward.

Guess I just need to have at 'er and see how it goes.

Thanks
Brett

[Moose]

Well, the servo/brake peddle assembly came out surprisingly easy. The master was reluctant to separate from the servo but an light stomp on the brake peddle soon sorted that out. I had to remove the mud shield under the wing so that the master had room to move out of the way, but there was no issue with the hyd. lines so all is good there.

Now the problem is separating the servo and brake peddle. No way does the pin want to come out. Not surprisingly, lots of penetrating oil has done nothing to help shift the pin. I think I need to get a little more serious so one night this week I will have to visit my buddy on the other side of town. He has a shop full of persuasion so the little bugger doesn't stand a chance.

Brett

[NickDawson]

thanks for keeping us posted - about to do the same repair and anxious to hear how it turns out for you. Out of curiosity which servo did you go with?

[Moose]

OK, I decided to revisit the servo/brake peddle this afternoon and was finally able to shift the pin through the peddle arm. Offered up the replacement servo and reinstalled the combo. Now I've run into another small problem. The non-return valve on the old servo had the hose barb at 90 degrees and it just touched the master reservoir. The replacement has the barb at a bit less then 90 and it is going to foul with the reservoir for sure. So, is it just a matter of popping the two valves out and swapping them? They are not threaded, just a pop in fit, but they are in pretty tight. Judging by the pic in the manual, they should just come straight out, but obviously I don't want to damage them. Tried two flat screw drivers, but the valve was being quite stubborn and I don't want to break it.

Anyone remove one before?

I suppose another option would be to pull the unit again and then "clock" the servo 180 degrees moving the non-return valve to the bottom. That would certainly solve the clearance issue.

Nick, not sure what servo I used. It was just a spare I've had sitting around for a very long time. If memory serves, it "most likely" came off a Ltwt. I have three and they all appear to be the same. My original (Series 3 88), the one that started leaking, which originally came from a 1982 Series 3 109, and the Ltwt one. I am also using the 109 master cyl. which has a bigger reservoir and is the reason I have a clearance issue now.

Brett

[Moose]

OK, I was able to swap the non-return valves quite easily after getting a tip to heat the rubber seals with a heat gun. Pop out, pop in, no fuse.

Everything is back together and my broken brakes are working better then ever.

Brett

[Nium]

Hadn't heard of the heat gun idea thanks for posting it. Will probably come in handy when working with press fit parts in rubber. Glad you got the servo sorted.

[daveb]

brett

amazed you never had to deal with this over so many yrs of rovering. consider yourself lucky. I've had to remove boosters this way a few times and you've seen my comments on the valves/grommets.

Guys, careful with the heat guns around rubber and plastic as it is easy to break down the material. I have had much better results by immersing plastic and rubber parts in boiling water for a few minutes and installing while hot. really does a better job heating the material throughout without melting the outer layer.

Obviously won't work with stuff that won't fit in a saucepan.

Also dish soap is a great help when fitting firewall/panel grommets, rad and heater hoses and the like.


Hadn't heard of the heat gun idea thanks for posting it. Will probably come in handy when working with press fit parts in rubber. Glad you got the servo sorted.

[Moose]

brett

amazed you never had to deal with this over so many yrs of rovering. consider yourself lucky. I've had to remove boosters this way a few times and you've seen my comments on the valves/grommets.

Hey Dave. I've only had to swap one servo before this, but it went in complete with a peddle box and master cylinder during a bulkhead swap, so that was a dead easy remove and refit. Guess they don't all get to be that simple eh. :D

I like your thinking with the boiling water to soften rubber bits. I have used that method before as well.

Brett

[markahendrix]

OK, I decided to revisit the servo/brake peddle this afternoon and was finally able to shift the pin through the peddle arm. Offered up the replacement servo and reinstalled the combo. Now I've run into another small problem. The non-return valve on the old servo had the hose barb at 90 degrees and it just touched the master reservoir. The replacement has the barb at a bit less then 90 and it is going to foul with the reservoir for sure. So, is it just a matter of popping the two valves out and swapping them? They are not threaded, just a pop in fit, but they are in pretty tight. Judging by the pic in the manual, they should just come straight out, but obviously I don't want to damage them. Tried two flat screw drivers, but the valve was being quite stubborn and I don't want to break it.

Anyone remove one before?

I suppose another option would be to pull the unit again and then "clock" the servo 180 degrees moving the non-return valve to the bottom. That would certainly solve the clearance issue.

Nick, not sure what servo I used. It was just a spare I've had sitting around for a very long time. If memory serves, it "most likely" came off a Ltwt. I have three and they all appear to be the same. My original (Series 3 88), the one that started leaking, which originally came from a 1982 Series 3 109, and the Ltwt one. I am also using the 109 master cyl. which has a bigger reservoir and is the reason I have a clearance issue now.

Brett

Brett - how did you get the pin out from the servo/peddle arm? Im in the same boat, and have been working on it for days. I got the pin to move about an inch (flush with the box) - but now I can't get it to budge. Ideally I wouldn't take the whole box out...which I think some other people have done.

[Moose]

Well, that was about 8 years ago now so I'm a bit fuzzy on the details. I had mine out of the vehicle so that made it a bit easier. I remember it took a while. I used lots of penetrating oil and once the pin started to move, I remember it would move a bit, then I would hit it back in. Then it would move a bit more, then back it. Just repeated until the pin finally popped out.

Brett

[cnfowler]

If I'm understanding the pin you're trying to drive out, labeled 564813 in this photo, then there is another pin that needs to be removed first. That's labeled 50446 in the photo. On mine it was very difficult to see. I drove it out with a small punch.

https://s19.postimg.org/k1wges9kz/Screen_Shot_2017-04-01_at_12.21.50_AM.png


Colin