80 mph @ 6000 rpm in 5th gear

[e30121]

I just bought a manual 1991 320i e30 cabriolet. On the way back i was doing 80 mph (wouldnt go over 80) at 6000 rpm in 5th gear is this normal ?
If not can someone tell me what could be the problem. Previous owner told me the engine had been rebuilt.
By the way im a newbie and dont know much about theese cars.

[bss325i]

Sounds like you have a 4.27 (or higher!) ratio diff in it or the engine is goosed!

[DHFiS]

Doesnt sound normal. Maybe the diff has been changed to one with the wrong ratio?

[PG325]

Sure you weren't in 3rd!

[e30121]

definatly not in 3rd

[E30BeemerLad]

has the car been converted from say a 318i to a 325?

[e30121]

Not that im aware of he said rebuild so probably not

[psychochild187]

how fast did you go in 3rd

[E30BeemerLad]

I see 3 possible issues

1- You were in 3rd
2- It has had the diff changed to a 4 pot diff
3- the instrument cluster has been changed with a 4 pot one and it has the 4 pot coding plug in still, so the tacho will be over reading - the coding plug is easily changed and if you are not used to 6 pot BMW's then they can sound like they are revving higher than they actually are.

Edit - I suppose the best way of testing theory #3 would be to give it beans in 1st gear, if the tacho goes off the clock then you have the wrong coding plug in, if it hits the rev limiter at about 6500 then it has the correct cluster/ coding plug

[bmwowner]

my 318i (m40) sits at just over 3000rpm at 70 and just over 3500rpm at 80.
the same as my sisters old e36 318i....

[StuBeeDoo]

Even if the car had a 4.45 diff, it would do over 100 mph at 6000rpm in 5th (118mph, to be exact).
Did it sound like it was revving its nuts off?? Just supposing that the car has been fitted with instruments from a 4-cylinder car and the coding plug hasn't been changed, your "6000rpm" would actually be 4000 which should be somewhere near right for a 320i at 80mph.

When you say "wouldnt go over 80" do you mean that you wouldn't drive over 80, or the car wouldn't go any faster than that?

[e30121]

I wouldnt drive it over 80 it was very close to the red line.

[E30BeemerLad]

If the car is still warm, go outside and start it up and give it a big rev up, if the tacho sails past 7k then I would lay money on it having the wrong coding plug due to an instrument cluster change (which would mean the mileage could be suspect)

What revs does it sit at on tickover?

[e30121]

Thanks E30BeemerLad ill try it. it sits at just over 1

[vokietis]

if your diff ratio is 4.45 it should do 80mph in 4th,or 80mph in fifth if your car has dogleg box.

[Jhonno]

Thanks E30BeemerLad ill try it. it sits at just over 1

Sounds like maybe you have 4 pot clocks in..

Does it sound like 6k? How far will it rev in 1st?

[bss325i]

if your diff ratio is 4.45 it should do 80mph in 4th,or 80mph in fifth if your car has dogleg box.

325i wont have a dogleg gearbox with 1.1 5th.

[vokietis]

it can have anything fitted,even m50 box

[bss325i]

it can have anything fitted,even m50 box

Yes other gearboxes can fit but its unlikey that it will have one.

Getrag 245 dog leg box's are very thin on the ground in the UK and were only available on pre sept '85 323i's and i think 320i's.

Getrag 265's from the M3/320iS dont fit an M20 unless you use a US spec 325e bell housing.

Again, very unlikely

[DanThe]

Lockwood dials with chrome rings?

[bpowell555]

I was getting 5000 revs at 100mph this evening... then I realised I was in 4th

[DavieP]

Just supposing that the car has been fitted with instruments from a 4-cylinder car and the coding plug hasn't been changed, your "6000rpm" would actually be 4000 which should be somewhere near right for a 320i at 80mph.

I drive a 320i auto and @ 80mph in top it is doing around 3400 rpm. Even the 'smooth' B20 engine note becomes a bit intrusive at a true 6K rpm so I doubt that many drivers would happily cruise mile after mile with that racket going on. It has to be a coding plug issue.

[Daf318is]

Something's not right there - that's kit car with bike engine territory!

[kniterider]

Silly question but does it pull ok? Clutch isn't slipping is it? My old pug was bouncing off the limiter for 15mins solid at 50mph (just) in 5th till I came off the sliproad, droppe a gear and the clutch went bang! Unlickley mind as I'd hope you would notice it.

[e30121]

If the car is still warm, go outside and start it up and give it a big rev up, if the tacho sails past 7k then I would lay money on it having the wrong coding plug due to an instrument cluster change (which would mean the mileage could be suspect)

What revs does it sit at on tickover?

I just reved it and it went past 7 rpm so i think E30beamerlad is right. Can somone please tell me how to change the coding plug?