P5B Towing Weight Capacity

[enigmas]

Hi guys, I'm in the process of buying a nice little retro teardrop caravan. Teardrops come under the category of a 'very light trailer' (up to 750 kg). So what is the towing weight capacity of a P5/P5B?

Any other personal experiences when towing with P5s would be welcome (for assessing/fitting relevant mods, etc., adding electric trailer brakes)

[Phil Nottingham]

Depends which regs apply and whether the trailer is 2 or 4 wheel and braked. But a braked two wheeler is up to its Kerb weight approx 1500Kg which it will cope with easily as long as the transmission, rear springs and rear end integrity are good

[enigmas]

Thanks Phil, so is 1500 kg what the Rover factory rated the car at or a personal assessment.

Any relevant personal towing experiences welcomed.

[Phil Nottingham]

Bit of both really as Rover never gave towing weights as I suppose they did not expect their luxury cars to be towing stuff (horse boxes?)  The Caravan Club of GB used a rule of thumb for braked trailors of 85% of the Kerb weight (1587 kg)  IMHO both 3 Litres and V8's can easily tow more than this but DG auto cars will need an oil cooler

[norvin]

In the UK you can only tow up to a certain weight if you took your driving test after 1997, if you did take it after 97 you then need to take another driving test towing.There are driving schools which will teach towing skills ready to take the towing test.

[stantondavies]

The 85% rule is the maximum recommended limit, though it is not necessarily illegal to go higher. The question is not whether the car is powerful enough, but rather that the trailer or caravan are not so heavy as to take control of the towing vehicle, especially downhill or in strong winds. The risk is snaking and losing control. A trailer or caravan can also be sucked into a snake by a large HGV passing close by. I recommend using an anti-snake device.

You'll have no trouble with a 750kg caravan as long as it is loaded carefully. All heavy items should be stored low down over the axle. DO NOT put heavy items at the rear or high up in the 'van; that will ruin the stability and is asking for trouble. Enjoy your caravaning.

I have been towing since 1967.

[Warwick]

Vince,
How big is this teardrop caravan going to be!?

[enigmas]

Thanks guys, I'm fine with the technical stuff. How about some personal experiences though. Stanton, you state that you've used your P5B for a lot of caravaning...could you elaborate on a particular trip/journey/experience. For example, what was the most comfortable cruising speed, how did you find the car's brakes, generally and down steep or lengthy descents, was the steering even lighter and more vague with the load, did you leave the car in drive going up hills or did you manually shift?

(I have several licences including light rigid and a taxi endorsement and have driven a bus load of kids (36) interstate numerous times with a large dual axle storage trailer attached. My experiences with my own modified MK3 comprise towing a small trail-a-boot trailer with the family interstate several times. That's 2 adults and 2 kids with a packed trailer. As far as caravaning goes, I don't have a clue as I've never done it.

Warwick. The teardrop van has a length of 3.9 metres x 2 metre width x 1.660 metres height. It's really not that big and only designed for 2 adults. The van I was looking at is right on the limit of weight for it's category, (probably over designed) which is as a 'very light trailer', (weight up to but not exceeding 750kg) anything over this weight requires trailer brakes, which I'd fit anyway, as I don't like the added inertia down hills.

[johnwp5bcoupe]

I towed in the late 60's to 1980 with selection of large cars, a Ford Zephyr 6,Jag Mk2, P5 MK2, P5 Mk3 and 2 P5b's all towing 16' plus caravans which were far heavier than than today's equivalent! and without doubt the P5 was the best tow car, the Mk2 on a holiday in Cornwall decided it was time due to tin rot to collapse one rear chassis member, but a block of wood and some fencing wire got us back home, in fact we went on to the Scottish borders for the second week and got home safely! that was her last journey The Mk3 was also a great tug until I got my first P5b the story was in the mag a while ago now. The car I have now was my last tug which was hitched up to a 16' caravan and a few car carrying trailers (my Grass Track days), the only problem I had was the brake fluid boiling away touring the Scottish Highlands! I would have no hesitation in saying the P5/P5b are great tow cars.

I never had any tow assist devices it for me was a case of just getting the weight correct on the tow bar, your little Teardrop should be no problem to your car vince

The Astral caravan we started out with weighed the best part of a ton (or more?) loaded, I was a bit Gung ho in those days

As Phil mentions the condition of the running gear is rather important I know yours is ok Vince

[norvin]

All very good advice from stantondavies particularly in regards of heavy trucks passing you, most modern caravans now have the stabilizer built into the caravan hitch and like stantondavies I would always use a stabilizer.

[johnwp5bcoupe]

Jan 26, 2015 9:06:28 GMT norvin said:

All very good advice from stantondavies particularly in regards of heavy trucks passing you, most modern caravans now have the stabilizer built into the caravan hitch and like stantondavies I would always use a stabilizer.

I suppose a lot has changed since 1980 Brian the lorries have got bigger and go a lot faster I would have thought the caravans would be a delight to tow these days?

[enigmas]

Nice stories John. I didn't realize you had so many P5s. Good to hear that the body is up to it. I like the block of wood solution to the rotted rear chassis member.

[norvin]

Jan 26, 2015 10:28:42 GMT johnwp5bcoupe said:

Jan 26, 2015 9:06:28 GMT norvin said:

All very good advice from stantondavies particularly in regards of heavy trucks passing you, most modern caravans now have the stabilizer built into the caravan hitch and like stantondavies I would always use a stabilizer.

I suppose a lot has changed since 1980 Brian the lorries have got bigger and go a lot faster I would have thought the caravans would be a delight to tow these days?

Yes John a lot has changed modern caravans tow well and lets be honest cars now are very nice to tow with and just think how speed limits have gone up over the years, we can now do 60mph on dual carriageways and motorways. The lorries that make caravan rigs snake the most are car transporters and so far nobody seems to know why, well not for sure.

[johnwp5bcoupe]

Jan 26, 2015 10:38:34 GMT enigmas said:

Nice stories John. I didn't realize you had so many P5s. Good to hear that the body is up to it. I like the block of wood solution to the rotted rear chassis member.

The P5 Mk2 was a good old car mechanically but rotten as a pear I remember hand painting it with Mat Black up to the trim level just to go on holiday
Yes I had one or few Vince!

[stantondavies]

Towing your tear drop caravan behind the P5B will prove a doddle; you will not know it is there. Modern caravans are almost TWICE as heavy as the equivalent back in the sixties.
I tow with a MkIII which doesn't have the torque or power of the 3.5 but even with a 3 litre you have to be careful to keep down to legal speeds. I have an automatic which will do a hill start in second gear on a light throttle with the caravan on the back. I rarely need to lock down going up hills. On a 3 litre, maximum torque is produced at 36mph which is ideal for towing.
I have had no problems braking; the 'van has its own over-run brakes. I do lock down on long descents.
The things to watch are manoeuvring, don't forget to allow a wider berth around tight corners or through gates. And snaking. This will, at best. frighten the pants off you; at worst, kill you. NEVER brake if you go into a snake. Take your foot off the accelerator, and hold on like hell to the steering wheel resisting the snake until the speed drops enough that the snake disappears.
Hope that answers your queries.

[kaiser]

Jan 26, 2015 8:34:41 GMT johnwp5bcoupe said:

I towed in the late 60's to 1980 with selection of large cars, a Ford Zephyr 6,Jag Mk2, P5 MK2, P5 Mk3 and 2 P5b's all towing 16' plus caravans which were far heavier than than today's equivalent! and without doubt the P5 was the best tow car, the Mk2 on a holiday in Cornwall decided it was time due to tin rot to collapse one rear chassis member, but a block of wood and some fencing wire got us back home, in fact we went on to the Scottish borders for the second week and got home safely! that was her last journey The Mk3 was also a great tug until I got my first P5b the story was in the mag a while ago now. The car I have now was my last tug which was hitched up to a 16' caravan and a few car carrying trailers (my Grass Track days), the only problem I had was the brake fluid boiling away touring the Scottish Highlands! I would have no hesitation in saying the P5/P5b are great tow cars.

I never had any tow assist devices it for me was a case of just getting the weight correct on the tow bar, your little Teardrop should be no problem to your car vince

The Astral caravan we started out with weighed the best part of a ton (or more?) loaded, I was a bit Gung ho in those days

As Phil mentions the condition of the running gear is rather important I know yours is ok Vince

I read this with interest, not because I am towing, but I have a P4 110 (Weslake head) and also a MKII 3.8 Jaguar.
There is no way I can even compare the torque and power between the two. The Jaguar is by far the stronger and more capable engine. I know the 110 is a 2.6 liter engine, but it has, according to the book, almost 125 hp if I remember right, very close to the output of the 3 litre, just shorter stroke. Is the 3 litre engine really that different and more capable than the 2.6???
Of your cars I would expect both the p5B and the MKII to be far better for towing

[norvin]

For towing the most important thing is torque walk onto any caravan site and you will have a tough time finding a petrol car (apart from mlne).

[kaiser]

Some figures:
P4 110:     123 ps, 142 lbft
p5 (MKII): 125 ps, 160 lbft
V8 3.5:      158 ps, 210 lbft
MKII 3.8:   220 ps, 240 lbft

If you had a 2.4, that explains the Jag, but that still makes the v8 more capable than any 3 litre. Overdrive and automatic might also have influenced it of course, but these are the figures.

[johnwp5bcoupe]

Jan 26, 2015 16:08:19 GMT kaiser said:

Some figures:
P4 110:     123 ps, 142 lbft
p5 (MKII): 125 ps, 160 lbft
V8 3.5:      158 ps, 210 lbft
MKII 3.8:   220 ps, 240 lbft

If you had a 2.4, that explains the Jag, but that still makes the v8 more capable than any 3 litre. Overdrive and automatic might also have influenced it of course, but these are the figures.

No it was the 3.8 it wasn't just the power I found the Jag made the towing feel tail happy probably to do the the suspension and the overhang, I didn't keep it long for that reason.
I wouldn't mind it now!!

[norvin]

Its the spread of torque over the rev range that counts, its no good if the torque range is say from 3000 to 5500 revs, the p4 hundred will reach maximum torque at 1500 what good is that it has run out of steam at only 1500 revs the idle is 500, look at the 80 that looks a better bet for towing on paper but that is a landrover engine and made for towing, this is why most towcars are diesel. The Rover P5B has a huge torque range and looks as if it could tow anything, automatic cars are great towcars shifting weight with ease.

[kaiser]

I think we have part of the answer, in the Jaguar not handling as well in the set-up.
As for torque, if the peak torque is at 1500 revs, it does not necessarily mean that the engine runs out of steam at that speed. Normally you would either show a graph, or give the rev range in which the engine produces 90 percent of peak.
The ideal engine would have torque flat as Table Mountain, but in reality, only steam engines and electric motors come close to that.
Typically a long stoke undersquare engine (where the bore is smaller than the stroke) typically English engines, will be good on torque and less good on revs. And everything else equal, you want an engine with peak torque as high as possible, but spread as wide as possible over the rev range. V8 engines are well known for excellent torque characteristics, high and flat torque curves throughout the range and so are many typical English engines.
                                           

Without a graph, it becomes difficult to argue, but I would be surprised if not both the V8 and the Jag engine has a higher torque over a wider range than any Rover straight six.

Torque curves for these would easily show that.

[stantondavies]

[/quote] I know the 110 is a 2.6 liter engine, but it has, according to the book, almost 125 hp if I remember right, very close to the output of the 3 litre, just shorter stroke. Is the 3 litre engine really that different and more capable than the 2.6???
Of your cars I would expect both the p5B and the MKII to be far better for towing
[/quote]

The MkIII auto has torque of 169 lb ft at 1750rpm. Generally speaking, the longer the stroke, the greater the torque. I would much sooner have plenty of torque than power.

[stantondavies]

Jan 26, 2015 16:08:19 GMT kaiser said:

........that still makes the v8 more capable than any 3 litre.

Maybe.....but don't underestimate the Weslake 3 litre. The torque curve is flat from the mid 30s to over 70 mph which makes it an ideal towcar - the best I've driven. And don't forget, the 3 litre has a lot more weight over the front wheels which aids stability.

[kaiser]

Jan 26, 2015 19:00:40 GMT stantondavies said:

Jan 26, 2015 16:08:19 GMT kaiser said:

........that still makes the v8 more capable than any 3 litre.

Maybe.....but don't underestimate the Weslake 3 litre. The torque curve is flat from the mid 30s to over 70 mph which makes it an ideal towcar - the best I've driven. And don't forget, the 3 litre has a lot more weight over the front wheels which aids stability.

Aha, yes, that makes sense, heavy in front would be good for a load at the back.
I'm looking forward to getting my 3 litre finished, so I can try it. I was thinking if maybe I should stuff a V8 in there, but I have since decided rather get the engine in good order and keep the car original. And in any case I have a V8.

[enigmas]

That's all good info guys. I like torque too, and as some of you may be aware, my Mk3 is fitted with a Leyland of Australia manufactured 4,416 cc (269.5 cu in) version of the Rover aluminium V8.

A few technical details and a bit of history for those interested.
The bore is 88.9 mm (3.50 in) and the stroke was 88.9 mm (3.50 in), making it a square engine. The block deck height was extended and longer conrods were fitted 158.75 mm (6.250 in) between centres. The engine produced 200 hp (149 kW) and 280 ft•lbf (380 N•m).

Export (to the UK) was planned. The closure by British Leyland of their Australian operations in 1975 precluded the widespread application of this engine. British Leyland did import one complete P76 engine for assessment but it was never fitted to a vehicle and was sold off on the demise of the company.