Diesel owners...manual gearboxes?

[Rommel]

A quick question- I don't know about the box or the ratios in the 2.5- what is the box doing in top at 70mph?
I'll extend the question to the manual 2.1 people as well.

I have often read people (journalists) saying the manual boxes are a bit rubbish but I don't listen to gossip- what do owners think?


Rohan

[citroenxm]

The box them selfs are perfectly fine, the 2.5 has cable change and is a slighty different beast to the 2,1 box. It also had hydraulic clutch actuation....

The 2.1 has Cable Clutch and rod linkages.. its the rod linkages that are crap in reality I THINK, but its always the BOX that gets the blame.

My 2.1 SED manual actually has a good change and doesn't feel that bad, but I have felt some bad ones too... My V6 24v S1 manual is one, as its the same box design, Reverse is a right PITA to get... but it could be as simple as adjustment..

At 70mph, 2,500 rpm? (2.1 box) The autos even though four speed rev the same.. 80mph at 3k?

I think the 2.5 has a longer lower 5th... however, others who have them will be along to answer properly..

[Peter.N.]

I think the 2.1 box is about 28 mph per 1000 rpm.

Peter

[endorfin]

I THINK (I can't check now as my 2.5 still has some problems and I'm still in Australia) it's about 2,600rpm at 80mph. But I could be getting mixed up with my VW tdi

[xmexclusive]

Speedo indicated speeds or actual speed?
There is at least 5 mph difference by 60mph.
On a 2.5 with a defective speedo I use the rev counter.
1750 rpm gives 10 times selected gear for speed in mph.
So 1750 in 3rd is 30mph and 1750 in 5th is 50 mph.
2000 rpm in 5th is 60 mph and 2250 in 5th is 70mph.
Checks some years ago with a HUD GPS speedo confirmed those speeds as midway between speedo and actual.
Was not cute enough at the time to note the front wheel tyre wear state as new to full worn can take 12 to 15mm off the wheel diameter.
Box ratios for 5th are: BE3 0.757:1, ME5 0.673:1, MG5 0.64:1.
Auto ratio for 4th is: HP18 0.74:1
Final drives are: BE3 3.938:1, ME5 3.933:1, MG5 2.417:1
Auto axle ratio: HP18 3.571:1
This then needs a list of tyre diameters for each model to complete the picture.
Box data is taken from the Russek diesel book.
Petrols are another set of variations.

Still looking at trying a set of oversize wheels on the front of a 2.5 or play with the box ratios.
See what difference that makes to fuel economy.

John

[Rommel]

John and Paul, thank you both. Excellent info.

[Rommel]

I just looked at that again and realised I got so absorbed in John's voluminous reply that I forgot entirely about Peter and Endorfin's contributions!
Apologies to you both, and thanks.

[Dieselman]

I think the 2.1 box is about 28 mph per 1000 rpm.

Peter

For the Auto, 27 for the manual.

[Dieselman]

The 2.1 has Cable Clutch and rod linkages.. its the rod linkages that are crap in reality I THINK, but its always the BOX that gets the blame.

My 2.1 SED manual actually has a good change and doesn't feel that bad, but I have felt some bad ones too... My V6 24v S1 manual is one, as its the same box design, Reverse is a right PITA to get... but it could be as simple as adjustment..

At 70mph, 2,500 rpm? (2.1 box) The autos even though four speed rev the same.. 80mph at 3k?

I think the 2.5 has a longer lower 5th... however, others who have them will be along to answer properly..

iirc, the 2.5 has the same overall gearing as the 2.1.

It is the linkages that give the notchy feel, there is no rubber in there so the gearstick feels all the metal contact.

My Cobalt car had a terrible reverse selection, which turned out to be the reaction linkage was out of adjustment.