the mysterous lost 7th Gear

[trapper]

I've recently bought a 1993 Leyland Daf MMLC and she's a beautiful beast, quite a step up from my Bedford MJ however I was expecting a little better motorway speed. I've heard a rumour that when the drops fleet was first delivered to Germany that there was a 7th gear to enable reasonable delivery times/speed and that once at depots the top gear was immobilised to leave the current performance limited to 45MPH. Does anyone have any positive knowledge as the whether this is just a rumour/urban myth or whether there is a 'hidden' 7th gear on these trucks?

[Richard Farrant]

7 minutes ago, trapper said:

I've recently bought a 1993 Leyland Daf MMLC and she's a beautiful beast, quite a step up from my Bedford MJ however I was expecting a little better motorway speed. I've heard a rumour that when the drops fleet was first delivered to Germany that there was a 7th gear to enable reasonable delivery times/speed and that once at depots the top gear was immobilised to leave the current performance limited to 45MPH. Does anyone have any positive knowledge as the whether this is just a rumour/urban myth or whether there is a 'hidden' 7th gear on these trucks?

I did a 3 week Mechanics course on the Leyland DROPS at Borden in 1991. All of the technical data we had points to only 6 forward gears in the ZF transmission.  The story you tell sounds like a myth I am afraid. We spent one whole week on the transmission, that is how intricate it is.

[wally dugan]

sorry a urban myth as Richard says a six speed box

[trapper]

Oh well, it was a nice thought at the time The six speed box is great for all the tasks required of the drops and I guess long distance motorway work was not in the original design brief but living in Scotland and driving 400 miles South for every event will always leaving clutching at these kind of straws..... Here she is arriving at my place last week.

[john1950]

As long as you are getting all 6 gears and the torque converter lock up is working thats the lot. There was some discussion a few years ago on this site about gear changing. If you go to Drops 8x6 auto box. 

[trapper]

The six gears are all there (2nd to 6th in D and 1st in manual) but the rumour about another gear when they were delivered reached me and I just couldn't resist the thought get getting up to 60 on the motorway The idea of a 7th gear for the long road trips and then disabled for it's military service did kind of make sense, it didn't seem so mad but if the experts say it doesn't exist then it must be so....... but that's what they'd say isn't it? It could be a conspiracy!

[MatchFuzee]

If you haven't seen this document already it is well worth reading:-

https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/519226/DE_S_FOI2016_03001___Attachment-_Truck_Load_Handling_DROPS_15_Tonne_8x6_LHD_MMLC.pdf

[john1950]

Was the Torque converter lock up disenabled on some trucks for some operational reason? This would have the effect of losing a gear, or rather the 6 intermediate gear ranges. When the vehicle moved up to 6th the T/C would not lock up so losing direct drive, or as you would say 7th

[trapper]

I have all (as far as I know) of the AESP's for both MMLC and IMLC and  I've done a fair bit of reading but the AESP's refer to the design operation and function, the rumour of a 7th gear was just for delivery and not part of the normal operation of the truck and therefore wouldn't be in the AESPs but would be a manufacturer setting that would have been disabled once the vehicles had completed there long European drive and were delivered to the Army.

 

[wally dugan]

l KNOW l have all the  aesps on both DROPS plus a whole lot more from concept to the end product. may be PAUL BROOK might like to comment as he was there at the begining

[Richard Farrant]

This range of ZF Ecomat boxes were only built in 4, 5 or 6 gear versions, the 6HP600 fitted to the Leyland was a 6 speed with torque convertor lock up.

I cannot see that a '7th gear' option was fitted just to do the delivery trip to Germany. Most British military trucks were geared lower than commercial line haul trucks. One limitation on speed was the cross country tyres fitted.

[paulbrook]

Urban myth.

The reason that DROPS is steady is that was what the Joint Service Statement of User Requirement (JSSUR) required - max speed 45MPH. So that is what Scammell and Foden worked to.

Remember that they replaced AEC Militants for the most part, so even 45MPH seemed quick.

Tyres happened to be rated at 55MPH.

 

 

[MatchFuzee]

21 hours ago, paulbrook said:

Tyres happened to be rated at 55MPH

Can the speed limiter be re-calibrated to 55mph? If yes, would this affect the insurance as the DROPS is no longer to the original military specification? 

[paulbrook]

1 hour ago, MatchFuzee said:

Can the speed limiter be re-calibrated to 55mph? If yes, would this affect the insurance as the DROPS is no longer to the original military specification? 

Don't think so - as I recall the gearing is such that you are out of power band revs on the Eagle 350 as you hit 45. The upside is that they are quite quick off the mark.

The other issue is that nothing on the thing is designed to do more than 45, so brakes, steering, suspension are all matched to that speed, not a higher one.

My strong advice is that if you want a faster truck, buy a faster truck.