X250 Drive line spec.

[rolandrat]

Perhaps Nick could throw some light on this. Is there a different driveline spec for a 3 ltr comfortmatic Van conversion and Chassis cab. I'm talking about the final drive ratio. The IH camper seems to be higher geared than the Autotrail chassis cab. I'm basing my question on actual ownership not an assumption.

[Robinhood]

...for the X290, the ratios are the same for the panel van and the chassis cab in matching 3 litre form (from Fiat's technical data).

 

I suspect the same would apply for the X250.

 

There is, however, a difference in ratios between the standard (light) and heavy (maxi) versions of both the panel van and the chassis cab.

 

If one vehicle had been based on the light version, and the other on the heavy, then there might well be a noticeable difference. (I think most IH are built as standard on the 35 light van).

[rolandrat]

Thanks for that Robin Hood, the IH was definitely higher geared than the coach built Comfortmatic I have now. The IH would cruise at 70 mph at very low rev's but if I cruise at 70 mph with this Comfortmatic there's a noticeable 200 rpm difference. Driven carefully the IH would do up to 28 mpg but this coach built is doing a little less. One thing very noticeable is that the coach built gets into 6th much sooner. The 3ltr is a cracking engine.

[Robinhood]

The picture below shows the ratios for an X290 3 litre 180 (standard and comfortmatic gearbox, which are the same ratios on this engine only) for the light and maxi versions.

 

1st thru 6th, reverse and final drive respectively from the top.

 

The differences are obvious (though I haven't done the calculations on overall gearing in each gear).

 

[rolandrat]

Thanks for that RH, just as I thought there is a difference with some.

[Derek Uzzell]

The intermediate and final-drive ratios for the transmission (manual or ComfortMatic) fitted to X250 models with the 3.0 litre motor were as shown in Robinhood’s image relating to the current Ducato X290, with the exception of the final drive ratio used with the X290’s “Maxi” chassis.

 

For Ducato X250 the final-drive ratio for Maxi chassis vehicles was 4.563:1 (73/16). For Ducato X290 the final-drive ratio for the Maxi chassis vehicles has been altered to 4.867:1 (73/15 - the Fiat datum is wrong). This ratio ‘shortening’ was advertised by Fiat when X290 was launched.

 

As the final-drive ratio of a 3.0litre X250 Ducato with Maxi chassis was around 7.5% lower than that of the non-Maxi version, the difference should have been noticeable if the two types were compared back-to-back.

 

The final-drive ratio of a 3.0litre X290 Ducato with Maxi chassis is now some 13.2% lower than that of the non-Maxi version and this reduction should be VERY noticeable if a back-to-back comparison were carried out.

[rolandrat]

Thanks for that Derek. The AutoTrail Trackers spec is built on the Fiat "Light" chassis and there's a noticeable difference in the drive line compared to the IH camper. The Comfort matic gearbox behaves far better in the chassis cab and wants to get into top gear much sooner than the IH did and remain in it for much longer so I think the fuel consumption will even out. As the driveline is slightly different the power transfer is more noticeable and rapid I'll need to keep a light foot on the power peddle. These Comfort-matics are brilliant, all they need is an exhaust brake.

[Robinhood]

rolandrat - 2014-12-01 10:30 AM

 

..... The AutoTrail Trackers spec is built on the Fiat "Light" chassis and there's a noticeable difference in the drive line compared to the IH camper. .......

 

....yes, I think I was wrong above and the IH Tio would have been built on the (Heavy) Maxi Panel Van. :-S

 

You will have different overall gearing as already discussed.

 

 

[euroserv]

Hello all.

 

I think you have this one well covered guys.

 

I actually wish they had not messed around with the ratios for 3.5T Maxi vehicles and just done it on the 4T + chassis. There was nothing wrong with the previous set up, particularly with the very torquey 3.0 engine. Higher revs will result in less economic cruising but better response when you want more go. Oh well.

 

Nick

[Derek Uzzell]

It’s stating the obvious, perhaps, but - besides intermediate and final-drive ratios - the rolling circumference of the motorhome’s tyres needs to be taken into account when making this sort of comparison.

 

If a Ducato X250 with 3.0litre motor has the same intermediate ratios for Maxi chassis and non-Maxi chassis versions and the same size tyres were fitted to both types of chassis, the effect of the lower (higher numerically) final-drive ratio fitted to Maxi chassis vehicles should be noticeable to a driver. However, Maxi-chassis X250s had 16” wheels whereas non-Maxi chassis X250s had 15” wheels and the greater rolling circumference of the tyres fited to the 16” wheels will redress the lower final-drive ratio.

 

A direct comparison of two vehicles' ‘overall’ gearing in top gear can be made when the mph/1000rpm figure is known for each vehicle, but I’m not sure if that datum is available for Ducatos. A rough calculation suggests that (for Ducato X250s with the 3.0litre motor) the bigger tyres fitted to Maxi-chassis versions pretty much cancel out the lower final-drive ratio fitted to that type of chassis. This may well explain why the final-drive ratio of the 3.0litre Maxi-chassis Ducato X290 has been lowered even further.

 

This seems to be at odds with rolandrat’s observations (assuming that his IH PVC had a Maxi-chassis), but there you go...

 

Regarding ComfortMatic, the fact that his Auto-Trail Tracker’s transmission shifts into top gear earlier and downshifts later than his IH did does not necessarily indicate different gearing. It may just mean that the ComfortMatic in his (2009?) Tracker has revised electronics to his (presumably older) IH’s ComfortMatic transmission.

[rolandrat]

Derek a lot of what you say is perfectly true. The IH Tio ran on 15 inch wheels and so does the Tracker. What is also noticeable is the speedo reads higher than the actual road speed so when doing an indicated 30mph it's doing considerably less. I will be doing a more accurate check on the rev counter and speedo shortly to compare the difference. You are also probably right about the electronics of the gear shifting as well. The IH in comparison did seem a shade lazy whereas the Tracker is eager to get on with it just like a true prancing horse.

[rolandrat]

Derek a lot of what you say is perfectly true. The IH Tio ran on 15 inch wheels and so does the Tracker. What is also noticeable is the speedo reads higher than the actual road speed so when doing an indicated 30mph it's doing considerably less. I will be doing a more accurate check on the rev counter and speedo shortly to compare the difference. You are also probably right about the electronics of the gear shifting as well. The IH in comparison did seem a shade lazy whereas the Tracker is eager to get on with it just like a true prancing horse.

[Derek Uzzell]

Forgive me for saying this, but it makes it hard to comment usefully on technical issues when the model and age of the motorhome(s) involved are not stated clearly from the onset.

 

I searched through earlier postings to try to establish how old your Tracker was but ended up guessing it was a 2009 model. I never managed to establish the year of your IH vehicle, but assumed it would have been older than the Auto-Trail and (as you were asking about X250s) hence 2006-2009. On that basis, I assumed the motors would have the same 157bhp power output.

 

There is a 2007 MMM review of an IH Tio R here http://tinyurl.com/bnnx5ww and there’s no indication that it was built on a Maxi-chassis. The photos suggest that the vehicle has 15” wheels (which you’ve now confirmed yours had) and there’s no reason to think that a version with 3.0litre motor/ComfortMatic transmission would have had otherwise.

 

As your Tracker and Tio seemed to have an identical specification in terms of motor and tyre size, I did wonder briefly whether the ‘motorhome’ Ducato chassis used by Auto-Trail for a Tracker might have different transmission ratios to that of the commercial van on which the Tio was based. Fiat has always said in its X250 literature that “specific ratios were defined for optimised performance on a motohome”, but I’ve seen no evidence to say that this is so.

 

With no apparent gearing difference between your Tracker and Tio, I came (tentatively) to the same conclusion as you - that the 200rpm difference at 70mph might simply be down to speedometer variation.

 

However, if the other factors are true - and the Tracker's and Tio’s top gear mph/1000rpm figures should be the same - a 200rpm variation at a 70mph speedometer-reading translates to a guesstimated speedometer accuracy variation of some 8%. Basically, if one assumed that your Tio’s speedometer were accurate at 70mph, this would mean that your Tracker’s speedometer is very significantly over-reading.

 

Alternatively, it could mean that there was a difference in the accuracy of the Tio’s rev-counter versus the Tracker’s rev-counter. There’s an attraction in the latter suggestion as an under-reading rev-counter might explain why the Tio appeared to be high-geared and was ‘lazy’ shifting between ratios.

[rolandrat]

Derek, The Tracker is a 2009 and the IH was a 2008, hope that removes any confusion, your input is appreciated as always.

Roland.

[rolandrat]

Derek, The Tracker is a 2009 and the IH was a 2008, hope that removes any confusion, your input is appreciated as always.

Roland.

[Derek Uzzell]

Thanks for the update.

 

I notice that, in the 2007 MMM article I provided a link to, Jonatham Lloyd said about the 3.0litre motor (with manual transmission) fitted to the Ducato-based Timberland Destiny on test

 

"If you want my opinion, the bigger 3.0-litre engine (Destiny) isn’t a perfectly tailored fit in a panel van-based motorcaravan of this size and weight. That it was powerful and indecently quick (30-50mph in five seconds) is beyond dispute. For me though, it felt hopelessly over-geared. Indeed, it always seemed highly-strung, as though it was on the edge of a nervous breakdown.”

 

As your IH Tio won’t have been very old when you swapped it for the Tracker, the comparative ‘eagerness’ of your present motorhome may be due to it having a lot more miles on it and being more fully run in than its predeccesor. It’s generally the case that a modern diesel powerplant’s performance will continue to improve until10k miles are reached. This wouldn’t explain the 200rpm difference at 70mph, but I don’t think you’ll satisfactorily resolve that without accurately measuring the speedometer accuracy of both vehicles.

[rolandrat]

I think Jonathan Lloyd just about sums it up with the panel van conversion and I agree entirely. This Tracker has only completed 8000 miles so needs some miles on it which it's going to get in the new year when we tour France and Spain.

[Brian Kirby]

rolandrat - 2014-12-01 7:48 PM..............whereas the Tracker is eager to get on with it just like a true prancing horse.

You have a Ferrari motorhome? And you're worried about final drive ratios? In a van capable of 170+MPH? Some folk worry over the least thing! :-D

[rolandrat]

Well said Brian, yes these 3ltrs need reigning in especially when they're in a small Tracker. A friend of mine though had his 2.3 Hymer remapped and left me for dead but there again he's a very fast driver all the time. It's true though what's been said about the 3ltr Timberland and IH, they're at their best on the open road because of the high gearing.

[rolandrat]

Well said Brian, yes these 3ltrs need reigning in especially when they're in a small Tracker. A friend of mine though had his 2.3 Hymer remapped and left me for dead but there again he's a very fast driver all the time. It's true though what's been said about the 3ltr Timberland and IH, they're at their best on the open road because of the high gearing.