Something just isn't right?

[Staty]

I have had e30's for years, over 10 of the bastards, but this is the 1st convertible I've had. It runs nice, sounds nice, pulls well through the gears, but feels like it revs to high for the speeds i'm going, very rarely goes under 3000rpm, i was cruising at 100mph and it was around 6000rpm, not far from the rev limit, i felt like there was a lot more to go and don't feel it should be revving that high. I use to be able to get around 145mph from previous e30's. Could do with an extra gear. Think something may not be correct in the drive-train somewhere? Diff or some ish? I have no idea what ratio the diff should be, any advice would be great as i want to get this car performing as it should, not driving like its holding back!

my car is a 325i cab 1988, pre face lift

Any help/advice would be appreciated as always.

[suchy]

Check what diff you have dude and report back...

[Staty]

I'll get the slag up on a ramp!

[Grrrmachine]

Have you got the right wheels on? Smaller rolling radius will curb your top speed too.

Other than that, it would be the diff.

[camcc]

Is it a manual or switch able auto? - if the latter and it is in sports mode it will stick in 3rd gear and will likely be revving around 6000rpm at 100mpdh.

[Staty]

I have 17' wheels on it, but I've had the same size wheels on a lot of my e30's, don't think its that bud, thanks though. Also cam, its a manual!

[ross2009]

that sounds like youve got a 4.1 diff or some thing in that

[Staty]

Coming back to this topic, I've just had the car up on the ramp and tried looking for an indication as to what diff i have on my car? All i could find was this

BM017

AND

1210411 E "Or what looks like an e"

Does anyone know what this means? I couldn't find any other serial numbers on the diff

Any help as always is greatly appreciated

Cheers

[Staty]

Hi guys? Any idea if these serial numbers mean anything? In my above post? Cheers

[tomislav]

There should be a metal tab about two inches long attached around one of the backplate bolts with the number on it.

It will probably be rusty so you'll have to do some scrapeing

[Staty]

Cheers bud, i did have a look, it was pretty rusty, couldn't see anything else really apart from the serial numbers listed above.

[jmc330i]

How many bolts does the backplate have? - as above, could be a small case 4.10 or 4.27

[Staty]

Fook knows bud, I'll have to have another look when its not wetter then an otters pocket outside!

[Rav335uk]

You couls have a number of diffs on a prefacelift.

3.64
3.91

or if it's a converted one to a 325i , 4.27

[Staty]

Cheers Rav, can what diff it is be determined from the serial numbers i put on my previous post? Or are they just random factory bmw codes?

[TheHeap]

You can check the ratio by turning the wheel and counting the turns on the prop to find out what it is.
There is a good guide on youtube

[Z3I]

My minds still boggling at the thought of 145mph in an old 325i cab!

[Rav335uk]

My minds still boggling at the thought of 145mph in an old 325i cab!

Don't worry Paul, it's called "Old Age"

[Brianmoooore]

Check that you don't have a four cylinder coding chip in the front of the instrument cluster before you spend too much time crawling under the car looking at the diff.

[Z3I]

My minds still boggling at the thought of 145mph in an old 325i cab!

Don't worry Paul, it's called "Old Age"

He he! I've only done 145mph in an E30 in my dreams!

[Staty]

You can check the ratio by turning the wheel and counting the turns on the prop to find out what it is.
There is a good guide on youtube

Will check that out, cheers bud!

[Staty]

My minds still boggling at the thought of 145mph in an old 325i cab!

ha ha, sure other folk on here have had a lot more out of there's!

[Staty]

Check that you don't have a four cylinder coding chip in the front of the instrument cluster before you spend too much time crawling under the car looking at the diff.

Where would this coding chip be and how will i be able to tell? Literally have no idea

Cheers bud

[Brianmoooore]

Coding chip is behind the trim panel between the top of the steering column and the cluster. Secured by two knurled nuts from behind.
You can check if you have the right chip without dismantling though: Any evidence that the cluster has been replaced? Does the fuel gauge give realistic readings? What idle revs are indicated? Does the engine rev easily past the red line?

[jmc330i]

Good call Brian, I didn't think about the wrong coding chip.
From memory, with a 4 pot chip in 6 pot clocks, once passing the red line the needle jumps all over the place.

I was thinking though, from an engine noise point of view, its fairly obvious when ones close to 6k rpm.
Although, my 318i revs around 4k rpm at 80mph, that's with a 4.27:1 diff I believe.

[Staty]

The fuel gauge doesn't work, think the sender unit has gone, it does feel like it would rev past the red line, as far as i can see there is no evidence that it has been replaced?

[Brianmoooore]

Have you ever had the tank more than half full?

[Staty]

Yeah had it full a fair few times

[Brianmoooore]

The reason I asked is because if a complete instrument cluster from a four cylinder saloon is fitted to a car with a 62 litre tank the fuel gauge will only show a reading when the tank is more than half full.
What's the idle revs when hot?

[Staty]

Ok i'm with you, idle's pretty much bang on 1000rpm when hot

[Brianmoooore]

Ok i'm with you, idle's pretty much bang on 1000rpm when hot

Or about X 1.5 what it should be.

[Staty]

Really? Something is definitely wrong then, think i need someone that knows what they're talking about to actually take a look at it, as you may have guess my knowledge of the mechanical side of e30's is minimum. I'll ask a couple of local people what they think. That instrument cluster that you mentioned, had a quick chat with Adi from Portsmouth, will see what he thinks, cheers for your help!

[Brianmoooore]

Take off the panel above the driver's knees, reach up behind and unscrew the two knurled nuts that hold the small trim panel between the steering column and cluster that I've already mentioned (push the trim panel in with the other hand) and remove it. Post up all the numbers on the white coding plug that is facing you in the lower right hand corner of the cluster.

[Staty]

You're a star! I'll crack on with this tomorrow and let you know, cheers again

[Staty]

Right, i have undone the bits of plastic that surround the steering collum, the bits that go under the steering wheel, i can't seem to get them fully off at the mo, however i have managed to pull the two bits of plastic apart enough to reveal what looks like what you mentioned. Got the serial numbers from a black plug type thing? This may not even be the correct thing? But the serial numbers on it are (058, 6131- 137 001)

Is this the thing i was looking for?

Cheers bud