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Discussion Starter #1
I need to replace my brake servo, but the bulkhead I swapped in (a row TDI bulkhead complete) had the entire assembly already, and I have no idea of the original donor vine to match the servo types.

I see two types of servos:
  1. Brake Servo Type 50 STC2878 227mm to HA701009 - Superceded from NRC4775 - non return valve bottom right.
  2. Brake Servo Type 80 NRC4772 276mm to HA701009 - non return valve top left.
Where the non-return valve is doesn't matter to me. Are these interchangeable on my bracket, or do I need to get this one right? One seems to have a bigger diameter than the other. Is that better?
 

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Discussion Starter #2
After more research, I see there are different part numbers for NAS D's, so now I'm really confused.

Here's a pic of mine.
 

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Discussion Starter #4
So got the new type 80 in the mail couple days ago and went to install it today. Fail. the new servo is definitely not a match. It's about 1" thicker front to back on the housing, the check valve is in the wrong location (Don't care about that), and most importantly, MC studs are completely different orientation. Type 80 studs are even with ground at 9-3 o'clock. my old servo however has the studs at a 45deg angle to the ground at about 10-5 o'clock (see pic below). If i had swapped my servo's today, when i remounted the MC, the fluid reservoir would have been listing outboard like the Costa Concordia.

I'm inclined to go with the new servo, as being much, much beefier, it looks like I'll get more power assist out of it for my fat beeyoch 110. looks like a straight match to the 4 pedal housing studs in the back.

So my question for the group is, does anyone know what servo i have? And assuming I'd have to swap the MC to match the studs in this conversion, would the pipes match right up or do they differ in thread size over the years?
 

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It is the same bolt patern has mine. Early 110.
When I changed the servo for a new one, the only diffetence I saw with other rover servo is the bolt patern.

Hope this helps,
 

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Conversion Question

Hi Guys, Thought I would try here first to keep the somewhat related topics tied. I have transferred a 4.2L into my 1986 110 RHD originally with a 3.5 and of course non-powered brakes. I'm not wanting to go to powered brakes, yet so wondering two things.

1. What does the servo do?

2. Can I connect the vacuum hose coming from the original master cylinder to the plenum on the 4.2L? Will it give me enough vacuum? I should say that I don't even know why I need vacuum, but I am assuming that it assists with pedal pressure?

See picture: I placed a red marker at the port available on the plenum and the original hose from the master cyclinder is a little to the left.

What do you think?
 

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That plenum fitting is what the 87-88 RRCs used to pull vacuum for their booster. You do need vacuum, as it 'energizes the back side of the booster to assist with pedal pressure.

Edit: i just saw the pen, no the vacuum line is bigger, like the one behind it.

-Jeff
Copy that. I just looked at it again and see that there are three ports on that side of the plenum. The smaller and larger ones you saw in the picture and then behind those two is a flat plug (no nipple). I bet that I could remove it and then insert a connector with a larger nipple to fit the hose coming from the booster like the one going to the emissions canister.

Thanks Jeff! I have never had to deal with a brake booster. I've been lucky in life with relatively little brake problems :) I suspected it needed vacuum and since the original post I dug into the shop manual and searched around a bit. I found a good way to test the diaphragm too on the forum, using a vacuum pump and gauge. Sounds like it hold 15-22 psi for 5 minutes.

Have a nice evening!
 
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