How much BUS HP do I need for a 16000GVM?

[Pedro_The_Swift]

Is there a technical reason for tag axles other than weight?
are discs (like with the Volvo B7R) worth chasing?

[donh54]

Is there a technical reason for tag axles other than weight?
are discs (like with the Volvo B7R) worth chasing?

The extra weight carrying is usually the main issue. Comfort is an added bonus, as the extra axle helps smooth out the ride.
You do need to be aware that tag (or "lazy") axles make it very easy to lose traction with the drive axle on loose surfaces or going over undulating ground.

For keeping up with highway traffic at 16T gvm I would suggest at least 280/300 horsepower ("real", not European)

Disc brakes will always out-perform drums, but it depends on the application as to whether it is cost-effective. Town running with lots of stop-start I'd go for discs. Long distance stuff, I wouldn't consider them a deal breaker.

[incisor]

Lots of [emoji590] questions floating around pete[emoji851]

[V8Ian]

Sorry, I'm a bit late to the party, Pedro.
How many ponies? Too much is never enough. I can recall when the average interstate prime mover had 180 -230 hp, nowadays even a garbage truck has 250 hp!
When I bought mine I was looking for 350hp, ended up with 360.
The Euros, as Don said, don't have the grunt of the Yanks, but nor do they have the thirst.
Driven sensibly, a bus towing a large 4X4 should give similar economy to a 4X4 towing a big 'van.
Generally, a highway coach will be a better buy than a route service bus. They've had an easier life, not stopping and starting every 100 yards and been navigated by more sympathetic drivers.
For my money, you can't go past S cam drums.

[Bigbjorn]

S cam brakes for ease of repair and reliability. As much horsepower as can be fitted in. What is in the one or ones you have been looking at? What size bus have you been looking at? How many bums? There are still good highway coaches around with 92 series Detroits in. These are long lasting and reliable, start easily in all weathers and get their ass into gear very smartly with excellent torque available from clutch engagement (800 rpm) up. Tag axles on forty footers and up were to get more legal load aka more bums on seats. As has been mentioned you can get dry bogged with tag axles. If you are going onto the dirt much with one then a Detroit locker in the drive axle is good to have. Amateurs often have a steep learning curve with bus transmissions mounted at the rear sometimes sideways or angled with long whippy linkage. Allison auto is to be preferred.

[gavinwibrow]

S cam brakes for ease of repair and reliability. As much horsepower as can be fitted in. What is in the one or ones you have been looking at? What size bus have you been looking at? How many bums? There are still good highway coaches around with 92 series Detroits in. These are long lasting and reliable, start easily in all weathers and get their ass into gear very smartly with excellent torque available from clutch engagement (800 rpm) up. Tag axles on forty footers and up were to get more legal load aka more bums on seats. As has been mentioned you can get dry bogged with tag axles. If you are going onto the dirt much with one then a Detroit locker in the drive axle is good to have. Amateurs often have a steep learning curve with bus transmissions mounted at the rear sometimes sideways or angled with long whippy linkage. Allison auto is to be preferred.

Concur with all this, inc DD6v92 donks.
One thing to watch - some caravan parks don't like tags cos they rip up the bitumen on the driveways, and with air suspension a single axle is more than enuff for the average RV. I'd also go for an auto for the older years - don't believe that most of your running will be open highway.
Pulling a 4.5T triaxle trailer with 4WD on board, my ex greyhound single rear axle DD6V92 and V730 auto trans used to get at worst 3 mpg at 100kmph

[Homestar]

Looking for something to tow the Disco with Pete rather than the other way around now? 😊

[Blknight.aus]

Scam drums, and FFS get the meritor style ones with the drum over the hub not the retarded suzi setup where the drum is inside the hub ala pre 2010 landy disc brakes.

the money you'll save when it comes time to swap out brakes in time alone is phenomenal. (and because the parts strip out so quickly doing bearing work is quicker easier as they are lighter to pull out)

[Bigbjorn]

Concur with all this, inc DD6v92 donks.
One thing to watch - some caravan parks don't like tags cos they rip up the bitumen on the driveways, and with air suspension a single axle is more than enuff for the average RV. I'd also go for an auto for the older years - don't believe that most of your running will be open highway.
Pulling a 4.5T triaxle trailer with 4WD on board, my ex greyhound single rear axle DD6V92 and V730 auto trans used to get at worst 3 mpg at 100kmph

The 6V92TA series were rated at 335 hp @ 2100. They can be tickled up to marine spec of around 400 hp @ 2300. Seem to live OK at that rating in boats. Clutch engagement torque @ 800 rpm was 720 ft/lb or 976 Nm. Maximum torque is 957 ft/lb @ 1300 rpm.

[djam1]

I live in a bus with a tag axle it’s an Austral bodied MAN
I tow a Defender on a trailer all up this weighs over 20 tonne
The bus has a MAN D2566 that was originally 280 hp with a 12 speed ZF
Not sure how many ponies there are left but towing the trailer up hills involves gear changing and slowing down
I think a few more horses would be better
Oh and 2.5-3 km a litre at upto 115 kmh

[DeanoH]

One of the more interesting setups I've come across was a gentleman with a very nicely set up tilt tray towing his van. He was into classic cars and used this combination when going to various 'meets' where he was able to buy a vehicle and transport it home easily. He could also put his small 4WD on the back when touring which gave him 'the best of both worlds' . He could also supplement his wallet by doing recovery work whilst traveling. All in all a pretty good setup IMO.

Deano :)

[V8Ian]

Here you go Pedro, all your problems solved.

The $1 million luxury motorhome built in Australia | Drive Car News (https://www.drive.com.au/news/the-1-million-luxury-motorhome-built-in-australia-125061.html'trackLink=SMH3)

Bet it's speed limited. [bigsad]

[harlie]

in a former life over 20 years ago, I peddled coaches (not a bus thank you) up and down the highway - at the end of what is referred to (by some) as the era of road travel - before affordable air fares. The 92 series Detroit ruled up until emissions regulations had them banned in new vehicles. The company I worked for had around 100 vehicles with the "Silver 350" because they were so reliable (Ddec removed on all of them - early Ddec gave issues that IMO were more down to the AUS installers and wiring more then the technology itself), very good power to weight, great to drive but being a 2 stroke they knew how to consume fuel and make noise. Torque was not their strong point. Every other engine (of similar HP) I drove was better at holding speed on a hill loaded.

If it was me and I was going to tow with it, I would definitely want a tag, that 3rd axel improved stability out of sight. I drove a Denning Landseer no tag a few times, exactly same vehicle as the tag models built in the hundreds that I probably did the most km in, same 6v92 but the AC unit was towards the front and no rest room/bunk (i think it may have been 38' instead of 40??) - the 2 axle version was no where near as stable on the highway and felt very sensitive to wind compared to what I was used to. 2 axel MotorCoaches (or MCA) at 40' were even worse. (would be more suspension geometry than extra 2')

ALSO Problem with buses as a tow vehicle is the HUGE rear overhang (distance from wheels to tow point) which is a lever for the trailer to boss the vehicle about. The old "Pie Wagon" freight trailers we towed with a ring feeder really changed the dynamics - they were around the 5t mark and I wouldn't want one behind a 2 axel coach (never saw one behind 2 axels).

An RV conversion would never need a Tag axel for weight limits, but for stability and piece of mind towing - yes please for a Tag.

Most Tag vehicles I drove had the ability to dump the air from the suspension so the Tag no longer carried any weight, which was very useful in slippery or tight maneuvering situations - quite a few will even lift those wheels clear and some companies instructed drivers to always use it in tight areas because it saved tyre wear/scrubbing - the vehicle had a noticeably better turning circle too. This system is an easy install if it doesn't already do it. This solution IMO solves the negatives of the lazy rear axel.

As to the HP Q: it depends on engine - the 360ish HP Scanias and Volvos were slower to accelerate than a 6v92 but held hills much better loaded. For me the pick engine for highway was Detriot's Series 60 - from the front all I'd hear was a bit of turbo whistle and speed hardly changed, I still remember the look on guys driving 75series landcruisers, HiLux ect as they pulled out to pass on black mountain (just north of Cooroy and now bypassed), they would have smoke pouring out the back as they flew up the passing lane, get about level with the steer tyres and then just go backwards as the S60 boosted up and 22t of 50' long, loaded bus dropped from 100kph to 99kph and then held it at 99 in top gear. The Series 60 was about 430hp (I think), much bigger displacement, but the vehicles were 15m long, 4.3 high and 22t+ loaded with duel tyre tag - and they used significantly less fuel than the 92.

Earlier comment about highway v suburban bus/coach - the highway coaches all had a higher ratio diff compared to town bus, so the town bus would pull away from a stop or red light nice and fast but would be screaming at 95kph

Also consider body type. The US running gear went in body + chassis that were 100% built here, nearly all the EU running gear arrived as a rolling chassis (which was funning to see driven around the yard) - the big difference was under the floor, the EU would have chassis rails running through the cargo bins where the Aus built chassis provide huge clear cargo bins even with the same body (like Austral/MAN vs Austral/Detroit) - in saying this, its over 20years since I looked at a coach closely.

The Austral Tourmaster/6v92 was probably my favorite drive from a driver comfort and handling perspective, from 1985 to the last ones (I think about 1989), their suspension set up and geometry was very similar to later Scanias and they handled perfectly - but that Austral body suffered from frame rust, I remember, the shrink panel being removed as early as 10years on some and the rust was alarming - Denning seamed to have built them a lot better. Volgren and Bova were mostly alloy framed above the floor.

As far as disc brakes go, I can't comment, never drove a disc braked coach, back then they were just appearing on Mercedes. The S-cam system was bullet proof and stopped plenty well - but no ABS.

Not long ago, I spotted a gumtree add for a 15m "MotorCoach Australia" with Series60 parked in a field on northern Gold Coast -for $15'000. painted all red and judging by the front shape it was ex MacCafferty's built around 1998-99. Will have a 7 speed fuller which was also bullet proof, no auto, no synchro, no problems!!

IMO the torque converter auto (slush box) coaches were terrible unless severely overpowered like several 8v92 installations or 6v92 in a lighter 2 axel. The auto shifting manual (with standard clutch) were great. Most auto coaches were Alison 6 speed with a small cat or cummins and IMO were just horrible.

Personally I'd be looking for a Volgren/Volvo, 3 axel if I was to do it. You will need to do a roof raise so don't worry too much about flat floor vs drop aisle.

[V8Ian]

Harlie, were you around in the heady days of VIP (Nambucca River Cruises after failing to take a bend jnorth of Kempsie [bigrolf]) and Deluxe?