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240 240 brake booster replacement - firewall bolts


Professional Amateur
Mar 11, 2015
Beaverton, OR
Hey everyone,

Since I bought the new wagon, brake pedal makes a whooshing/airy noise when pressed, feels kinda weird (little bit squishy, sinks a bit when holding it at a light) and slightly changes idle when pedal fully depressed. Brake performance itself seems fine, but I suspect the thing's leaking.

Went ahead and got a whole reman booster. Went to install it today and for the life of me I couldn't get a wrench on the upper left firewall nut. :oops: All the previous threads say it's easy, but the clutch pedal brackets and pivots are in the way for me. Tried combinations of long socket, short socket, swivel joint and extension - no luck. Either couldn't get the socket onto it, or if I disconnected the ratchet I could get the socket hooked up and then couldn't finagle the ratchet back on without dislodging the socket. Ended up giving up and bolting it back together for now.

What's the secret here? Some sort of offset wrench? More extensions (I think I'd hit the HVAC/brackets if I extended in a straight line)? Remove entire pedal box and bracket? :grrr:
Pretty sure they are all 13mm - I can get my socket onto it by itself, I just can't seem to find any configuration which gets around all the stuff under the dash so I can actually rotate it.
Yeah you need a lot of extensions. Break the nuts free. Then use a cordless ratchet(if you have one). Also would not recommend a reman booster. They are all junk. Secondhand is usually the best option in this case.

Also if something is in your way, remove it. I've done them on lots of cars and it is a pain especially if it's got cruise control crap(I'm pretty I sure remove that stuff).
Yeah you need a lot of extensions. Break the nuts free. Then use a cordless ratchet(if you have one). Also would not recommend a reman booster. They are all junk. Secondhand is usually the best option in this case.

We'll see if it works or not, since I already have it. :e-shrug: If not I guess I'll be trying to warranty it.

Do have a cordless ratchet, and I have a lot of 1/2" extensions but only a couple short 3/8" ones. I'll be picking up a pack of extensions next week and we'll see if the extra length helps get around the brackets. Maybe some wobble joint(s) too instead of this crappy u-joint.

Worst case I guess I'll plan to take all weekend next week and pull the pedals out to get at it.
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Yeah, long 3/8" extensions with either a wobble end or a ujoint extension works well. Even with cruise control I was able to get the extensions in there to get the nuts.
You do not need to remove any pedals

What you do need is the right tools

Hence me coming here to ask what tools I need. :v

Was looking at the HF wobble extension set, that seems like a good option if the 15* of wobble is enough. Maybe the ball and socket style ujoint as well.

Also gonna get some ratcheting box ends too to make the bolts on the MC end less of a pain.
Yes, those are good. I'd want to have both the wobble and ujoint extensions handy. I recently bought some ujoint extensions. There is a internal spring so they are a bit easier to use. These were at Advance Auto so there are probably a few places with them. The ratcheting box for the master cylinder is a big help as well.
Did this last weekend. Figured I should come back and leave some notes should anyone find this thread in the future.

The Harbor Freight wobble extension set was all I needed to reach the bolts from the inside. Definitely recommend - gives you enough flex to get around obstacles but doesn't bind or lock up. I just connected all the 3/8" ones together from largest to smallest - that way it curves more at the end. Get your extension snake + socket on the bolt first, then hook up your ratchet and break it loose.

Power ratchet was nice to make it go fast but with that many extensions, I could have managed without it - it brings the ratchet out past all obstructions and gives you room to work. I would recommend a good headlamp or work light as it's hard to see down under there, especially the upper 2 bolts and you really do not want to try and land the socket blind. I did the left 2 bolts from outside the car and the right 2 lying upside down across the front seats - but if you have a bad back or aren't very flexible, I'd say you may want to pull the front seat for maximum room.

I only needed to remove 4 pieces from the interior to get at all the bolts: the underdash mat, floor vent, and a couple relays (one on each side) which were clipped directly between me and the bolts. On the outside, it will tilt and slide out pretty easily once you have the master cylinder unbolted and the vacuum line disconnected, but you may need to wiggle around some harness components and/or the clutch cable to get it out. Recommend getting a replacement vacuum hose, mine was all dried out and kinked at one end. I hadn't thought to buy any hose ahead of time, so I just cut the kinked / cracked ends off for now and re-routed it above instead of under the booster. :oops: Will grab some new hose next time I'm at the store.

The interior nuts on my car were all 13mm. Deep socket wasn't necessary. Don't use a 1/2", that's only 12.7mm and the nuts are pretty bang on size-wise. Exterior nuts are pretty big, maybe 16 or 17mm. None of my nice new box ends were big enough so I had to use an adjustable. When reinstalling, you can use a bit of thick grease or putty to stick the nut into your socket+extension combo, then carefully thread it on by hand before torquing.

The Bentley manual says to remove and replace the firewall seal, but my reman booster had the seal molded in as part of the boot, so replacement wasn't necessary. Boot also has some filters in it which weren't present in the original - I presume they're to keep the booster clean and muffle the noise from operation.

Overall pretty happy with the reman so far. Much quieter, doesn't change the idle or sink when held down. Brakes don't feel more powerful really but I think the squishiness is reduced. There's a very slight idle hiccup if you slam and release the brakes but I suspect that's normal since the booster lets some air through to operate.
Did you take out the instrument cluster? Really helps your view of things in that area.

Probably would have helped introduce more light yeah. Not sure it would have helped with access very much since the HVAC tubing and a lot of wiring/brackets are between the cluster location and the firewall bolts.