Are 4/6 pot brake servos all the same? - Vacum pipe entry?

[Brian28]

I'm swapping 4 pot to six pot, manual gearbox. Is the rear gearbox mount/bracket the same for both? Same question for the brake servo, does the vacum pipe have the same entry/exit spot on the servo body? I have a 318is complete, and a load of M20 stuff that will be going in, not a complete M20 car to compare with.

Thanks
Brian

[bimanut]

The gearbox cradle is different between the two as the M20 box sits at a different angle to the M42 box.Not sure about the rubber mounts but i think i have used both on an M40.Better to buy some new ones"while you there"

Servo`s are all the same across the range,unsure about lengths of vacum pipe.
Dont forget the 6 pot coding plug for the clocks.

[Brian28]

Thanks, and sh!te. Off to the wanted ads for a cradle ....

[Brianmoooore]

If the M20 has the complex double non return valve for the servo, it's worth (to simplify future maintenance and tidy up the engine bay a little) using the simple non return valve from the M42, along with the later 325 convoluted air pipe without the branch, to replicate the servo feed arrangements used on the last of the 325s.

[Brian28]

Thanks chaps, anybody have a couple of diferent cradles they could compare? Found one in the garage that looks the same as the one off the 318is but only things I broke there recently were 6 pots, and realOEM is showing 318 part number the same all across the range?

[Brianmoooore]

That's because you've been given duff info.
All manual E30s use the same gearbox support crossmember, and all autos use the same (different) crossmember.
The problem arises if you try to fit a gearbox from an engine that sits at one angle to an engine that sits at the other angle, when you will have to fabricate your own or modify one.

[Brian28]

Ar5e. Sorry Darlow!

[Brian28]

Engine and box in, prop etc all done so the heavy end is over, plumbing and wiring to sort.

Is the servo pipe in the same location? The pipes look miles away from the grommet on the servo body. I had the M42 on carbs so the pipework was modified to suit the new manifold, I can't remember what the old set up looked like.

If anybody has a photo of M20 engine bay with servo pipes that'd be handy, thanks.

[Brianmoooore]

Inlet on a 325 servo is half way down the right hand side (looking from the front), The long complicated M20 air valve is the reason for this, and it's going to be difficult, or inelegant at least, to connect to a servo with the inlet in the four pot position.
Best solution is to convert to the late 325 arrangement, as I suggested earlier in the thread, but alternatively, unbolt the servo, and turn it over.

[capri_rob]

If the M20 has the complex double non return valve for the servo, it's worth (to simplify future maintenance and tidy up the engine bay a little) using the simple non return valve from the M42, along with the later 325 convoluted air pipe without the branch, to replicate the servo feed arrangements used on the last of the 325s.

Does anyone have a pic of this setup so I Can see what I either need to look for secondhand or what combination of bits to order from the stealers ?

[Brian28]

It's what I ended up doing in the end (thanks Brian), you will have the opposite problem to me though, ie servo take off point too far away. Should be easy enough to rotate it through 180 degrees though. Will get a photo up later on.

[Brian28]

I've blanked off the original top pipe from the TB with a bolt. I have another one to do in a couple of weeks (a 316 this time) and I think that the 316 vacum pipe should be useable, blanking off one of the TB pipes as in the photo and blanking off the air pipe elbow. I was lucky with this one as I had the elbow-less air pipe kicking around in the garage from one I broke a while back.



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