Alfa Pages

[LDA]

hey all,

i used to read the old list on this site a few years ago, boy was i glad to see a forum in its place now!
i've just taken ownership of my second 33 perm 4 and i'm glad to say its mostly in mint condition. i'm trying to learn more about how the 4wd system works.

1)how does the ecu control the electro coupling? and when does it come on and off?

2)there are some strange parts to the alfa 4wd system. there is the viscous coupling. what purpose does this serve?

3)and there is the huge flywheel just before the rear axle. i assume this is there to help the rear wheels keep turning while changing gear etc.
what is it's real function? and would removing it result in less weight on the drive line and thus faster acceleration and more power to the wheels?
or mess things up totally. how does it act along side the viscous coupling?

4)both the p4's i've had are very low on the front suspension. is this due to the front shocks giving out (had an mot not too long ago and it passed fine) or are they just meant to be that low?
i'd like to uprate the shocks and springs all round but i dont want to lower the front much more as its quite low anyway.
would new shocks (prolly koni) and springs sort the ride height out anyway?

5)brakes.
yep its an old alfa and its got rubbish brakes. no surprises there.
i think part of the problem is that the master cylinder is too small for the job and needs to be swapped for a bigger one. are there any other alfa's that i could pull the cylinder from or is it an aftermarket part i need?

6)last but not least.
workshop manuals or other information about the 4wd system. where on the internet could i find such information to download?

thanks in advance

Luke.
_________________
A good workman allways blames his sh*t tools.

[Matt Stolton]

1) The ECU engages the coupling at power up (as key goes to position 2, the 4x4 light should go out within 1-2 secs). The ECU also has a speed sensor reading from the speedo, and a brake switch which tells it when the brakes are appplied. If you are braking harder than 0.2G, between two certain speeds, the ECU will disconnect the 4x4 at the EMC, to stop the rear coming round to say hello. Once your foot is off the brake, the ECU spends about 30 seconds trying to re-engage the EMC, before it gives up and turns the warning light on. However in my experience, it tends to be about 5-10 secs and the timer starts once below the lower lmit of the speed envelope. This is generally from motorway speeds to stopping at roundabouts on slip roads. The coupling usually has a spasm (4x4 becomes lit) in this scenario, but especially with traffic lights about. I believe the Traffic lights sensors in the road interfere with the hall effect probe mesh sensor, so the ECU panics and disconnects the 4x4.

2) Most 4x4 have 3 differentials. Only one shaft would come out of the gearbox, to the first diff. This then feeds 2 axles forward and rear, each axle having a their own diffs in the usual fashion. The P4 has the driven shaft of the gearbox drive the front diff, and hence front wheels. However the shaft, also extends out of the rear of the box, and is then coupled at the rear of the box to the EMC, which is ECU controlled of course. To allow slip/slight changes in axle speeds front to rear, a viscous coupling tranfers the power to the rear diff. If the front wheels are slipping, it locks to let the rear to drive at full "torque". If the rear slip, it allows a difference in axle speeds so the front will dig in. In reality it works better than it sounds it will.

3) Your guess is as good as mine about the rear flywheel, it could also be there to tune a resonance at a certain speed, as well as to smooth the rotation of the shaft in times when the viscous is allowing slip, and the shaft would not be receiving so much drive. Alfa, not one for adding unnecessary weight to a car, have put a large lump of metal on for some reason, so I would be tempted not to ask too many questions about its removal.

4) I think because the rear is so high(er) than normal, it makes the front look low, or the extra height at the rear, makes the weight act more on the springs at the front. Either way, it is nort a geat issue, and I wouldn't worry too much.
Keith is seemingly always on the scrounge for front struts/springs, as he always seems to think his front is sagging. Given his knowledge, I'm not going to doubt his observation, but I think part of the look of the P4 is some sort of optical illusion thing compared with regular 16V. If you do a have a lower than normal front due to age issues, then springs/shocks could help. However most aftermarket springs are lower anyway, so kinda defeats the object. However, lowering the rear could visually raise the front perhaps? I have Eibachs on mine and that looks and handles fine, being slightly shorter, but progressive.

5) Brakes - Go after market front calipers on bigger discs. I actually used Alfa 75 Brembo twin pots on 285 discs, but aftermarket would be easier and cheaper, with much less agro. You will obviously need, as part of the kit, a spacer bracket to increase the ability of the caliper to stand off from the strut. However, do a search for a post I did about big brakes, which shows a picture of my setup. You will get the drift.

6) Tino does a sort of bible of the P4. It explains most of what I've just said, with more thorough background and original documentation. It also has the instructions for fitting a P4/P2 switch, which is something I will do sometime.

Overall, the P4 is unusual, but it does work, although you will have to brave with your clutch to stop the engine bogging down to perform a quick standing start. However, once rolling, wet or dry, the P4 grip levels are awesome.
_________________
Regards

Matt

Ex Alfa 33 'GTA' (P4 with Knobs On)
Now cruising in a 166 3.2 Ti!!

[LDA]

thank you very much for your detailed reply.
thats given me loads to think about.

your reply about how the ecu controls the 4wd was interesting. the light only ever comes on in my car when i turn the key. it goes out shortly after.
it never comes on while i have been driving in either of my P4's.
i'd best go and do some more reading.
Tino you say? who/what are tino? and how might i find them?

the 2wd/4wd switch.
this mod had been done to my old p4. it cooked all the wires, a relay and the EMC.
i dont see the point in turning your P4 into a scrabble wheel drive car. you might save a few pennies on fuel but that's not what the alfa is about.
i would not do this mod to my current P4 for fear of doing lots of damage to the 4wd parts.

then again i have no idea if the mod was done correctly on my car or not. as it was done before i had it. it ended up with me getting a new EMC and having to replace a lot of burnt wires and some relays.

L.
_________________
A good workman allways blames his sh*t tools.

[Matt Stolton]

Tino is one of the moderators, and has held a long association with this forum, even before I got involved as a newbie. He is currently going under the handle of tvatavuk, so you should be able to PM him, or he will read this and direct you to a copy of his 4x4 manual.

The only thing I can fault with the manual, is his infatuation with the two brake switches. He has told me on the Forum, and in the manual, that they have to both work simultaneously. However, one is soley to do with the brake light, as normal, and the second one is soley to do with telling the 4x4 ECU that you are brakeing, so it can consider whether to disconnect the EMC. I can't see why they have to be engaged/disengaged by the brake pedal at identical times, but he reckons they have to. I am not going to disagree......

I'm sure Tino will read this soon, and I'm sure I've misunderstood the brake switch function, and will correct me, but apart from that minor thing, he's your man for P4 electronics. I haven't done his mod to P2/P4, but as far as I can understand it holds up to inspection, and I will do it someday. Like most things anything done badly will fail, but done correctly, should be OK. In all fairness, I was thinking of putting the switch in series with the fuse the sits in the relay which powers the whole 4x4 system. With the switch open, there is no power to the ECU or EMC, so it will naturally tend to stay open.

The EMC is an interesting device in itself. It has a drive shaft running through it, from the gearbox, which sits on a couple of bearing, which sit in the ali housing. Fitted over this shaft is a large electro magnet, which enegises behind a large disc with fine teeth on, which attaches by splines to the driven shaft. Sitting oppposite this is a large brass "piston", with a steel insert that is mounted with a little travel due to some small springs, into the brass piston. The magnet enegises and pulls the brass mounted steel cog to mate with the other cog, and they mesh together transferring drive to the rear of the unit, where the rear prop shaft attaches to, just before the viscous coupling. The two 'cogs" are seperated by a small spacer, and all three are numbered to match (brass/steel cog, steel cog and spacer). These are obviously machined together to make a set. It is the small spacer that holds the brass cog and steel cog apart under P2 conditions, and the P4 only works when the coil is energised and the steel insert in the brass piston is pulled to mate with the main steel cog. There is only a nats nuts of space between P2 and P4, so it is amazing it works at all.

If you get a spare one, take it to peices and have a look. I have "serviced" 2 now, which work fine so if I can't break them any one is worth a try!!! You can easily get hold of the two gearbox oil seals (one for the gear selector shaft, and one for the EMC driven shaft), and the paper gasket between EMC and box, and are only around £5 each from memory.

The other odity is the hall effect mesh sensor. This sits under the EMC, partly held in by the 1" thick peice of hard rubber which is the joint between EMC and the gearbox rear support/selector arm support. My dad once had a Vauxhall Cavalier 4x4, which sounds like it had a similar viscous type setup, and his disconnected at traffic lights, over the 'in road sensors'. Mine occasionally does the same. Perhaps I have a nervous ECU, or a dodgy wire from the mesh sensor to ECU, but mine occasionally cuts out too.

Regarding the brakes try hispec motorsport, or click on this link to see the topic with pictures of my front brakes.
_________________
Regards

Matt

Ex Alfa 33 'GTA' (P4 with Knobs On)
Now cruising in a 166 3.2 Ti!!

[tvatavuk]

Hi.
Matt, job well done, very detailed information.
I was reading it but there was nothing to add.
I’ll be probably contacting you in near future about including it in P4 bible as you call it, if you have some pictures of disassembled EMC it would be great.
I’ll jump into wiring diagrams and get back to you concerning possible urban legend about Siamese brake switch


2 LDA Sorry to read that P2/4 mod switch cooked all the wires, a relay and the EMC on your previous P4.
I would be interested in that cars history (previous owner, who has done conversion, was it with original 4x4 switch or diy…) if you don’t want to write it here you can PM me.
Document Matt talks about is for DIY 4x4 switch, if you want it send me your e-mail.
As I see it , best thing about P2 mode is when you park car, you can turn full lock without causing stress to whole 4x4 system or to look at it from financial side less need to replace hard to find 4x4 mechanical parts, weld chassis and such.
_________________
Tino Vatavuk
Little black dress which replaced Alfa Romeo 33 S 16v Permanent 4 GMo

[LDA]

hey tino,

the mod was done to my car before i owned it. i bought it from a dealer and i didnt realy know that much about the p4 back then
it was from teh southampton area that i bought it. so maybe the owner from local?
it seemed to work for a while. the switch was an extra fog light switch in the dash that turned the 4x4 on or off.
after about 6 months the 4wd system packed up. the garage that had a look at it was an alfa specialist and they showed me all the melted wires and the alloy filings coming from the EMC.
at the time i didnt have enough money to fix it so they took the prop off and left it at that.

the car is now a fully working p4 again but it wasnt me who fixed it. i sold it with a few burts hydrolic tappets. and no working 4x4. i'm not sure if that owner or the current one finished off fixing the 4x4 but i saw it a couple of months back and its all working fine again now.

thank god my current p4 is all ok and has not been chopped up by some nutter with a wite cutter.

L.
_________________
A good workman allways blames his sh*t tools.

[paulhide]

Hi Luke, good to see you a couple of months ago at the owners meet and glad to see you’re back in a P4. Just showed Dave Peters this evening what a P4 can do in the back lanes behind where I live. (I’m driving Luke’s old P4 along with three series two 1.7s and my girlfriend drives a 1.5 ti) Bought it from a guy in Kent with loads of niggly problems, but have now pretty much fixed all of them. Recently changed poorly lowered front suspension which kept understeering and it now handles beautifully as it should. I was going to sell it, but now it’s working so well I’m becoming more and more reluctant to do so. The P2/4 switch works fine, although I don’t think it was a very smart idea to put it next to the fog lights in case you accidentally press it instead of the fogs when accelerating or braking. Yeah, the only time I use P2 mode is for parking so as not to strain the system. Latest addition is a ramair system from the front spoiler to the K&N filter which seems to work fine. Paul.
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Owner's Club 33 Registrar. Now from P4 & S2 1.7 QV
http://www.alfa-pages.co.uk/viewtopic.php?t=5188

[LDA]

hey paul.

when you say front spoiler do you mean the vented intake next to the fog light?
i used to have a pipe that came up just under the filter through a hole in the inner wing there. my new one has only got a short pipe that doesnt quite get as far as the back of the bumper.

L.
_________________
A good workman allways blames his sh*t tools.

[tvatavuk]

2 Paul
Great now we know who owns it now.
Do you know how 4x4 switch is installed, where do wires go?
_________________
Tino Vatavuk
Little black dress which replaced Alfa Romeo 33 S 16v Permanent 4 GMo

[LDA]

they go to a blue relay near the battery on the left of the heater. its a rhd car.
the switch is next to the fog lights to the right of the steering wheel.
the wires from the switch and to the relay were replaces after they meltd a little. nothing too bad but i didnt like the look of them. had to stick a new relay in there too.

when i had the car i found a website with instructions on how to do the 2wd switch mod. many hard drives later i have managed to lose that data but it was only like 2 or 3 pages of info when printed. and was quite well written.

it looked to me like the switch just cut the power to the relay. but that was a few years ago now and my memory isnt as sharp as it could be.

L.
_________________
A good workman allways blames his sh*t tools.

[LDA]

just spent a few mins searching the net but i cant find the page. it may not exist anymore as its been a few years.

L.
_________________
A good workman allways blames his sh*t tools.

[tvatavuk]

It was probably my web, well written you say then probably not.
So by the looks of it you could only disengage 4x4, you needed to restart engine to conect 4x4?
There are 4 wires to that relay, 2 that power up power hungry beast called EMC, if it was placed on one of those, no wonder they melted.
But if it was placed to relay feed, as I described then it is strange.

Anyway if you need that same document mail me. I changed also number of HDDs from then but I should be able to find one of versions.
_________________
Tino Vatavuk
Little black dress which replaced Alfa Romeo 33 S 16v Permanent 4 GMo

[paulhide]

Yeah, that's right Dave Peters gave me a perfect piece of tubing to go next to the fog light and I've fixed some wire mesh over the front to stop anything unwanted ending up shot over the K&N. By the way my 4X4 warning light never flickers on when in use near traffic light sensors. Have got the pages about the DIY switch on a CD and printed out. Yeah, best to switch between 2 and 4WD with engine momentarily off, but possibly okay when simply stationary. Happy motoring. Paul.
_________________
Owner's Club 33 Registrar. Now from P4 & S2 1.7 QV
http://www.alfa-pages.co.uk/viewtopic.php?t=5188

[LDA]

tino,

just had another question pop into my head.
the fly wheel on the back end of the prop shaft. what is its function? is it to help dampen some vibration or is it to help keep the prop spinning when the EMC is off?
or something else i havent thought of?

L.
_________________
A good workman allways blames his sh*t tools.

[tvatavuk]

Propshaft will rotate when EMC is off, because in that scenario rear diff is spining it. There is no real center diff, so visco and first prop will spin also.
Just like Matt I also assume flywheel is there to dampen vibration.
_________________
Tino Vatavuk
Little black dress which replaced Alfa Romeo 33 S 16v Permanent 4 GMo

[tvatavuk]

After 60sec look at P4 documents, on page 2 I found all about 4x4 ECU diagnosis I needed.
Matt sorrry, both brake switches need to be in sync.
I'll add link in this post tomorow containing that page.

Here it is 354kb :
Page2.bmp
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Tino Vatavuk
Little black dress which replaced Alfa Romeo 33 S 16v Permanent 4 GMo

[James D (guesting)]

Hi All,
I agree the front springs on the P4 are low - mine were so low I couldn't slide my hand between the front tyre and the wheel arch. I replaced the original springs with springs from a series 2 33, the wire is a little thicker in diameter. This lifted the front 20mm and gives a ride height somwhere between a standard car and the P4. Now the front bumper doesn't scrape over kerbs, nor does the suspension bottom out.
Best wishes
James.

[LDA]

mine never seems to ground out on anything. i was just wondering if they are meant to be that low. i can get my hand on top of the tyre. just.

L.
_________________
A good workman allways blames his sh*t tools.

[Thunder]

Hello everybody

first i'm sorry but as you can see my english is not very good...

I've got a 33 P4 and i've seen this topic witch is very interesent.
it's a very funny car i love this engine in particular.
if you had some document about this car i'll be very happy to see it.

thanks