Designed as a successor to the very old but successful Fairey overdrive, offered by Land Rover as an option since the days of the Series I, the Roamerdrive is a very tough unit which gives similar performance benefits to the older unit but with much less noise. Gear selection is notchier, even when bedded in, and the amount of throw on the lever is quite a bit longer, but those are the only detractors over the original overdrive model.
The Roamerdrive uses long epicyclic gears with a central sun shaft, three planet gears and an outer ring gear to drive the output shaft. The use of SII/early SIII 3rd/4th synchro units for the selection mechanism is a simple way of ensuring the owner has easy access to replacement of the main service wear item, though the service life of the unit should be very long due to its very sturdy construction.
It shares its oil supply with the transfer box, which means that it’s less likely to run low on oil than the Fairey design, which had its own oil supply which tended to disappear through the seals into the transfer box or out of the top breather vent. With the included Rocky Mountain finned transfer case bottom cover added to reduce oil weeps and vastly increase oil heat dissipation, the unit runs cooler than the Fairey design, too.
It is a very expensive item; I bought mine for a little over £800 when they were introduced, but the current price is between £1300 and £1400. You need to cover a lot of mileage for the unit’s fuel savings to recoup the cost, but it does make faster travel possible and, in Tdi equipped vehicles, reduces engine and transmission noise vastly. Taller differential swaps from later models into Series Land Rovers are a cheaper and simpler option, but they tend to be too tall unless far more powerful engines have been added and lack the flexibility that an overdrive offers of dropping down to standard gearing whenever desired. While a Fairey unit is much cheaper (even if you can find a new one), I wouldn’t recommend the older design behind a V8 or Tdi as the small splines on the clutch sleeve and input shaft will not last long.
The value for money of this product is very user specific. For frequent long-distance drivers, especially with more powerful engines, it is far more beneficial than to those with less powerful engines, short-distance driven vehicles where a Fairey unit would suffice, if needed at all. What I can tell you is that I’m glad I upgraded from my Fairey to the Roamerdrive.
Effectiveness: 8/10
Value for money: n/a
I fitted my DS Roverdrive into my 2002 TD5 powered defender 110 in 2010 with the intention of towing a 2 ton caravan around Australia using 4th gear and overdrive instead of putting stress on fifth gear in the R380 when towing.
So far I have found the transmission runs considerably cooler in 4th gear with Roverdrive than when I towed in fifth, I also feel I get more engine power when towing than when using fifth and not using overdrive ( the overall gearing is similar in both arrangements).
I have had no problems at all with the Roverdrive over the past 5,000kms and find it very smooth and quite in operation and would recommend to others. As I service all my equipment myself and mechanical engineering my passion and business I monitor performance and durability constantly, so far I have not been disappointed with Roverdrive engineering quality.
Hi Everyone, I’ve just had a roamerdrive fitted to my Defender TD5 and while it certainly cuts noise and revs I feel the fuel consumption may have gone up! Could there be a fault somewhere along the line? My OD was fitted by professionals no problem there- and it came brand new from the box so no problem there either. Perhaps they have to bed in and settle down or something like that. I’d be pleased to hear from anyone who may know more.
Hi David,
I doubt you have anything wrong at all, it’ll just be that the overall gear ratio is too high for best fuel efficiency. I had a simar but even more exaggerated situation using 3.54 diffs on the 109 (same ratio as yours, but the Series high range is 1.15 reduction as opposed to your 1.4, the overdrive being barely useable with that combination).
Defenders have taller ratios than the earlier 90s and 110s, and much taller than the Series vehicles. Their standard configuration is a compromise for the various uses, including heavy loads and towing, so for a private use vehicle without towing, the standard fifth gear and high range are a bit low. The problem you have is that overdrive raises it by about 28%, which is just too much for the engine size without it working hard, just like selecting too high a gear on a pedal bike.
So, the overdrive will be helping make long range drives quieter and more comfortable, but at the cost of a bit more fuel. Slightly smaller tyres will be a help, and given the extra performance of a TD5 over a TDI, I’m mildly surprised you have any significant fuel consumption increase, but if you are using oversized tyres, then that would explain the issue – each step from 205/75 to 235/85 to 255/80 gives approximately 10% final hearing increase, so standard tyres (235/85) would be best.
If you have bigger tyres and need them, or have heavy loads, a trailer or roof rack and other external accessories like I do that greatly increase drag, then the other option would be to change the diff ratios to something closer to 4:1. I know there are 3.9:1 and 4.1:1 sets available that will drop all the gear ratios in high, low and overdrive, making the high 5th with OD much better while also giving an extremely low low1st, giving huge torque, improved engine braking and crawling ability. 4.1:1 ratio would drop the gearing by about 17-18%, which is perhaps a bit much. I’d guess that 3.9:1 would be ideal for what you have, but I’d be interested to hear more about the vehicle to have a better idea of what is going on as I’m guessing a bit.
Nick
Hi Nick
Thanks very much for getting back to me. It is TD5 and I have fitted BF Goodrich all terrains which are quiet and have never been, and still aren’t, I think, a problem. I do have a roof rack but I always had one before fitting the OD. Surely if the diff ratios were a problem Roamerdrive would have mentioned it? How would I go about changing the diff ratios to 3.9:1?
Many thanks for your help
David
The tyre brand I always important than the size. Are you using 235/85R16 (standard size)?. If you are using larger tyres than that, your fuel economy will suffer.
The Defender Roamerdrive is based on the Series unit. The Series transmission was very low geared due to the simple engines. With a v8 or TDI, the series is underrated even with the overdrive.
Unfortunately, as the Defender was already more appropriately geared to its higher performance engines, the same % step up from the overdrive is a bit much for Defenders with high weight or external accessories (especially roof racks). It does a good job of reducing engine and gear box noise, and fourth gear with overdrive will be higher than fifth without it while keeping hear box temperature lower (fourth gear is direct transmission with the input and output shafts locked together, an no torque directed through the gears) which should give you a small improvement in fuel consumption over standard.
Changing diff ratios is not a job for the inexperienced. Xtreme4x4 and Ashcroft Transmissions could advise you on prices of replacement diffs ready for simple swap with the existing diffs, but it may cost as much or more than the overdrive did if you include the labour.
Hi has anyone had any experience with running one of these overdrives with a 2.8tgv engine? Mine is tuned running roughly 300lb ft @ 1400 rpm and 255/85/16 BFG muds. Gearbox is a 5 speed tremec same as in Dodge Viper and 5th gear is slightly taller than r380 5th. Just wondering if i fitted one of these it would be too high geared to bother with? Also what is the life span of these? Thankyou any info much appreciated
I honestly don’t think the Roamerdrive will struggle with the TV, given how many are used behind tuned TD5s, Tdcis and V8s. My only criticism of the units is that they used cheap bearings and the rear most bearing on the sun shaft suffers if there is any oil issue. I had this bearing fail when I had a transfer box oil leak on the 109, and I know of a Defender version failing in the same manner, though I don’t know if it also suffered low oil.
If you replace the bearings with good quality bearings, which wouldn’t be especially expensive, and keep an eye on oil levels, then I’d be surprised if you ever had a problem.
Hi, I had a roverdrive fitted to the series 3 gearbox of my landrover two years ago. It has work smoothly up to a week ago. Now it “crunches” when I take out of roverdrive, but not when I engage it. Has anyone got any idea’s what is wrong.
Hi Tim,
Assuming that it’s only the overdrive that ever crutches, not the gear box, then a dragging clutch Canberra eliminated. That narrows the potential causes to the synchro unit and gear wheel dog teeth.
The unit uses a Series III (Suffix A-C) 3rd/4th synchro unit. These are prone to wearing their three leaf springs at their centre hump, which leads to spring failure. I. The gearbox, this normally causes a jam of the hub in its neutral position, locking out 3rd and 4th until the debris is cleared (which can cause other problems if it damages teeth or bearings). It’s quite common.
Those springs are not to hold the unit in gear, as is frequently misunderstood, but only to apply pressure from the synchro hub to the baulk rings, pressing them against the gears’ synchronising cones during gear changes. If the springs are missing or damaged, then the baulk ring will not engage the synchro cone to synchronise the hub and gear during selection.
If you remove the rear half of the overdrive, you’ll see the synchro unit straight away and will be able to check those springs.
If they’re ok, then my suspicions would turn to the teeth on the synchro hub and the corresponding teeth inside the gear at the back of the front half of the overdrive, and the condition of the baulk ring (the bronze phosphor ring of the synchro unit), whose very small “Toblerone box” teeth may have worn out.
I would check the condition of the bearings at both ends of the sun shaft that the synchro hub sits on (the rear bearing is hidden at the back, but check for play and smoothness, the front bearing is inside the planet gear carrier but the shaft’s bearing surface is exposed for easy inspection. These bearings don’t tolerate oil starvation and their failure could cause shaft misalignment and selection problems, though I’d expect a lot of rumbling either engaged or disengaged. I had both fail on mine, and the rumble and subsequently found play were very noticeable.
Hi Nick
I really appreciate all the good comments on the Roamerdrive over the years. Since you purchased on of our early units we have built many thousands more. All our competitors have folded their tents and left.
A point that needs making to your readers is that we have a policy of steady improvement to our products and the Roamerdrive had a major upgrade about ten years ago. The changes and the reasons are technically interesting
AA We stopped using the Series 3/4 Synchromesh as the supply of good quality ones dried up and a series of horrid aftermarket ones flooded the market. So we switched to using the 4/5 synchromesh from the LT77. A vendor then pointed out that BMW used a similar but better one with solid sliding keys so this is what we use now. (The two are interchangeable)
BB The thinner synchomesh allowed us to shorten the housings so you can now mount the overdrive on a Series without splitting the housing.
CC More space allowed us to used a more robust bearing on the rear end of the sun shaft – this pushed up the power handling capability significantly.
DD We changed the oil path through the unit by opening up the front wall and using the spiral groove to simply hold oil behind a dam on the front cover.
EE All the major components like the gears have remained exactly the same as the day we started nearly twenty years ago.
Britpart distributes for us these days and I miss having a booth at the old Billing Show. I’m busy building up a 101 expedition vehicle with an ISUZU 4BD2T motor.
My best regards and appreciation
Ray