Thread: Roverdrive

Originally Posted by Eddie S

Anybody using the Roverdrive behind their series 3? just wandering what they're like, and are they ok behind a 186 Holden motor. Or are they troublesome like the Fairey O/D,any responses are greatly appreciated. Eddie S.
fai

Eddie

If you are talking about the Roverdrive from Roverdrive Corp in BC Canada, they are an excellent overdrive, much quieter than the Fairey or Toro brand and because of the epicyclic gear design using components from auto transmissions designed to go behind big Yankie V8s they are very reliable.

Usually too expensive for most people to buy, but if you can get one they are a great unit. They also make an overdrive for the LT230 and were about to release one for the LT95 although there was a delay re-designing the flange where it bolts on.

Diana

Can someone explain how these bolt on overdrives work? Is it basically that an extra gear is added to the box? Driving the car, do you shift into neutral and then engage your overdrive or do you stay in 4th gear, and does it change the ratio of all the gears? I assume it drives back into the box, not to a seperate output?

Originally Posted by pfillery

Can someone explain how these bolt on overdrives work? <snip>

the bolt on overdrives fit into the rear PTO hole of the transfer box and replace the mainshaft rear constant gear with a pair of concentric shafts.

The inner (input) shaft is locked onto the gearbox mainshaft and the outer (output) shaft replicates the tooth count and cut of the mainshaft constant gear. At the back end of the two shafts is a gearbox. In Fairey and Toro it is a system of two counter rotating shafts (in Fairey some parts out of a Rover 2000 car), for the Roverdrive it is an epi-cyclic (planetary gears) design.

When the Overdrive is "not engaged" (although in truth it is) the overdrive input and output shafts are locked together and rotate at the same speed, replicating the usual top speed. When the overdrive is "engaged" the input shaft drives through the O/D gearbox which rotates the output shaft something around 27% faster than the mainshaft, hence overdrive is obtained.

The overdrive can be used in all gears, including reverse, giving 16 forward gears and 4 reverse in a series transmission, although in truth the O/D should only be used in 3rd and 4th Hi range. Gears must be engaged otherwise you are in neutral with no drive.

In some boxes like the Defender R380/LT230 4th OD is roughly equivalent to 5th normal which makes the O/D less functional than in the series boxes where the OD usually splits 3rd/4th. The result in a series box is a spread of ratios:3rd; 3rd-O/D; 4th; 4th-O/D.

Hope this helps.
Diana

Thanks for the explanation Diana. I had seen them fitted to cars but wondered exactly how they interacted with the existing systems. When I used to have an old beetle, you could get a 5th gear kit for the original beetle gearboxes, but this essentially was an added gear to the original box, you pulled out the original selectors and one of the shafts replacing it with the new parts thus converting the 4 speed into a 5 speed. Pretty pricey though at around $1300 for the kit back in the early 90's.

Pitty the boffins can't work out a way to do this on the Landy gearbox, I'm sure there are ways to convert them to a different box - I guess as long as the outputs are there you can connect anything to anything these days. Seen a couple of Ford c4 auto conversions done bolted to either a 250cu 6 cylinder or a small v8 which aparently work really well but would no doubt involve major modifications. Must be a 5 speed conversion you can do relatively simply. From what I've read on these forums about overdrives they are very noisy.

I've been looking at the Roverdrive, been thinking of it, but I'm worried the standard gearbox behind a 186 aint much chop, don't want to throw away money for nothing. Marks adapters in Melbourne use to make a 5sp Nissan kit to series Landy - dont do it anymore. Anyone out there no of any 5sp conversions? Are the HSTC any good? Most people I have asked say they work well. Any comments most apprieciated.

Originally Posted by Eddie S

I've been looking at the Roverdrive, been thinking of it, but I'm worried the standard gearbox behind a 186 aint much chop, don't want to throw away money for nothing. Marks adapters in Melbourne use to make a 5sp Nissan kit to series Landy - dont do it anymore. Anyone out there no of any 5sp conversions? Are the HSTC any good? Most people I have asked say they work well. Any comments most apprieciated.

Here you go....Ashcroft Transmissions

Just a bit of information about a lot of these 5sp adapters. Yes you can fit them in relatively easily so long as you can also adapt the engine to the respective box.

However because of the design of most if not all of these adapters you can not retain the PTO output necessary for your Thomas PTO winch etc.

If a PTO is as important to you as a 5 speed gearbox, then you may want to consider using a 110/Defender transmission instead of the series transfer. (Not that PTO outputs for LT95 or LT230 are easy to come by either).

Your other option is to change to a Toyota Land Cruiser 5 speed transmission and maybe even the Toyota diesel engine. (Now I will go and wash out my mouth with soap for mentioning the TLC words.)

Originally Posted by kaa45

Here you go....Ashcroft Transmissions

What do you think? 186 Holden would be easy to fit an Ashcroft 5 sp conversion to standard series T/C? There is an adapter plate behind the 186 where the L/D GB bolts onto. All gearleavers come up through the same floor holes and to my knowledge the drive shafts are unmodified from T/C to Diffs.