Top Speed not great

[Galahad]

I find myself back in Transit Smiley ownership!!

I've got a Sprinter recovery truck, but it needs lots of work, obviously can't be without a working truck so bought a 1999 DI beavertail as a stop gap so I can continue to work.

Unlike previous Transits, this one is built like the proverbial tank!

Chassis is in great condition, and recovery bed is over engineered with thick steel, makes for a heavy truck which isn't ideal when trying to stay legal lol

Took it to Birmingham today with quite a weighty load on the back, travelling mostly on the M5, and the old girl did well.

However a few issues have been raised by this journey.

Speedo said it was doing 70mph, GPS showed it was doing 62/63mph. Engine is proper howling at this speed, which is odd as I've had Transit recovery trucks in the past that could do 80 at least, so long as any pesky hills didn't show themselves!

Someone in its past has fitted newer twinwheels, not 14" but off something much newer (16"?) but I'm wondering if the tyres are too low a profile or maybe its a combination of rear axle ratio and wheels.

Any advice.

[Noctule]

Smiley twin wheels take 185/80r15, and if I remember correctly the rims can't be swapped for 14" rims.

The 16" rims from mk6 and mk7 can be modified to fit simply by drilling out the mounting holes to suit 16mm studs. These rims take 185/75r16, which has a rolling radius barely any larger it's not worth mentioning so won't make any difference to your real speed compared to the speedo.

This website has a good tyre size calculator...
http://www.tiresize.com/comparison

62/63mph by satnav with 70 on the speedo is comparable to my twin-wheeled hi-cube, which will do about a genuine 75mph in favourable conditions.

It's more likely your new smiley has a less speedy rear axle, good for tugging weight but hell on the ears.

I have a letter G on the plate in the passenger footwell, which means 4.63 axle ratio.

IMG_20221129_2318510.jpg

Chassis plate decode thread is here...

viewtopic.php?f=31&t=10363

Mat