4wd To 2wd Conversion?

[Fly By Night]

Hi Everyone,

With fuel prices soaring I was just wondering whether there was any benefit to downgrading my '96 SWB from 4WD to 2WD. As it is generally only driven in fair weather and never off-road I don't have a real requirement for the 4WD. Am I oversimplifying the conversion by saying that all I should need to do is to remove the appropriate drive shafts and/or prop shaft?

Has anyone done this conversion? Did you notice a difference in fuel economy? Is it wise to do the conversion from a safety point of view? Would you disengage the front wheels or the rear wheels? Would my insurance company need to be notified of the conversion?

Any opinions would be greatly appreciated.

Thanks,

Paul.

[bitman]

@paul,

your reading my mind as i was thinking of doing the same with both my rav4's.

i think that disengage the rear wheels is the easy option since the front wheels are connected on the transfer box. i was thinking of removing the drive shaft from the transfer box to the rear differential.

if i have the time i will see this weekend if that's an option.

may be anchorman can shine some light on this?

[Fujisan]

Hi Everyone,

With fuel prices soaring I was just wondering whether there was any benefit to downgrading my '96 SWB from 4WD to 2WD. As it is generally only driven in fair weather and never off-road I don't have a real requirement for the 4WD. Am I oversimplifying the conversion by saying that all I should need to do is to remove the appropriate drive shafts and/or prop shaft?

In theory no, you're not oversimplifying it......in practice I see dark clouds ahead

Has anyone done this conversion? Did you notice a difference in fuel economy?

If they have they are keeping quiet about it. Unless you ditch great chunks of metal to reduce wieght, I doubt you'll save much more than a couple of mpg, something a light right foot can achieve easier.

Is it wise to do the conversion from a safety point of view? Would you disengage the front wheels or the rear wheels?

Think you would have to make it FWD.

my insurance company need to be notified of the conversion?

OH YES!

Any opinions would be greatly appreciated.

Thanks,

Paul.

IMHO I don't think the time, effort and cost (including lose of value - would you buy a highly modified car?) of the conversion will ever be paid back by the fuel savings.

[Hoovie]

Based on no facts, but just gut feelings, I think the conversion will cost more then it will save, and the Insurance will be a BIG factor.

Even though there are 4x2 RAVs as well as 4x4 RAVs, to turn one into the other is the type of conversion that will lock you out of most of the lower cost, better value insurers - so if your age/driving experience/claims record normally allows you a good deal, wave goodbye to that.

Even IMPROVING the brakes oftens gives you a hike in insurance costs, even thoiught you would logically think it would make the car safer.

As Fujisan says, a lighter way of driving will usually save you a lot more then these kind of changes - I have changed my driving style in the last 3 months and am probably 20-25% more economical now.

How I will ever approach Bitmans economy though, I will never know :)

[anchorman]

Paul

Yours IS a 2WD unless you engage the diff lock. There will be no benefit in further modification.

Bitman

Yours is permanent 4WD but easy to convert. You must leave the prop shaft from the transfer box to the centre bearing in place as it is a splined sliding joint into transfer box. Mark the drive flange after the centre bearing with paint so you can always relocate it when you want to. Remove the rearmost short section from the centre bearing to the rear axle. I then suggest you try it. You can expect it to behave differently in that it may spin the wheels when starting on a steep uphill gradient in the wet weather. Also it will handle more like a van without the rear wheels connected and may swing out more easily when cornering at speed. It is the latter that Hoovie is rightly warning about in terms of insurance implications.

However, we shouldn't fit performance chips or anything other than tyres that the vehicle was Type Approved/Homologated with and still we do.

You will have to judge if the effort is woth it in terms of economy.

Leave the orange half to spin on the centre bearing and remove the rear half at the green flanges after marking them up.

[john1944]

Paul

Yours IS a 2WD unless you engage the diff lock. There will be no benefit in further modification.

Bitman

Yours is permanent 4WD but easy to convert. You must leave the prop shaft from the transfer box to the centre bearing in place as it is a splined sliding joint into transfer box. Mark the drive flange after the centre bearing with paint so you can always relocate it when you want to. Remove the rearmost short section from the centre bearing to the rear axle. I then suggest you try it. You can expect it to behave differently in that it may spin the wheels when starting on a steep uphill gradient in the wet weather. Also it will handle more like a van without the rear wheels connected and may swing out more easily when cornering at speed. It is the latter that Hoovie is rightly warning about in terms of insurance implications.

However, we shouldn't fit performance chips or anything other than tyres that the vehicle was Type Approved/Homologated with and still we do.

You will have to judge if the effort is woth it in terms of economy.

Why not buy a bicycle, you could get down to one wheel drive then !!!!

Leave the orange half to spin on the centre bearing and remove the rear half at the green flanges after marking them up.

[RaverT180]

Hi Everyone,

With fuel prices soaring I was just wondering whether there was any benefit to downgrading my '96 SWB from 4WD to 2WD. As it is generally only driven in fair weather and never off-road I don't have a real requirement for the 4WD. Am I oversimplifying the conversion by saying that all I should need to do is to remove the appropriate drive shafts and/or prop shaft?

Has anyone done this conversion? Did you notice a difference in fuel economy? Is it wise to do the conversion from a safety point of view? Would you disengage the front wheels or the rear wheels? Would my insurance company need to be notified of the conversion?

Any opinions would be greatly appreciated.

Thanks,

Paul.

Oh my Gawd, Check with your insurers first, co :D uld be a problem with a major mod like you are thinking of. I've found that just a little restraint on the right foot has given me a minimum of 5mpg on my T180 mind you need that to pay for the blo**y run flat tyres!

ATB

J

[bitman]

:D super anchorman, i was thinking more or less the same kind of mod. will have a look at it over the weekend if the 3 doors isn't in use. also will have a chat with those toyota insurance boys / girls. when i had my 1967 land rover and disengage the freehubs it made a huge difference in mpg. also the steering was a lot better. so i will give it a go and keep all parts so easy to reconvert it back.

can't do the 5-doors since it's still in warranty. the moment that's of i will throw lpg in.

[bitman]

It is the latter that Hoovie is rightly warning about in terms of insurance implications.

@hoovie, what about your cruise control and your insurance?

[bitman]

How I will ever approach Bitmans economy though, I will never know :)

daily commuting crawley <-> guildford

[Fujisan]

Just a little example of the nearest modern car I could find that is close to the RAV:

Nissan Qashqai

Petrol

2.0 Tekna 2wd 5dr - 199 CO2g/km - Combined 34.4 mpg

2.0 Tenka All-Mode 4wd 5dr - 204g/km - 33.6 mpg

Diesel

2.0 dCi Tenka 2wd 5 dr - 183g/km - 42.8 mpg

2.0 dCi Tenka All-Mode 4wd 5dr - 183g/km - 40.9 mpg

So as you see very little difference in the combined mpg figures between the 2wd and 4wd models. IMHO loses due to extra friction, roll resistance etc will be negligible. What difference there is can only really be explained by the wieght saved in the 2wd model.

Therefore, taking out one section of prop shaft, IMHO isn't going to achieve a lot.

[Hoovie]

It is the latter that Hoovie is rightly warning about in terms of insurance implications.

@hoovie, what about your cruise control and your insurance?

Interesting question - Cruise control is not changing a characteristic of the cars handling or performance, I would say.

Cruise Control is not taking away anything or replacing anything, unlike a 4WD-2WD conversion, or an Power chip or upgraded brakes - It is along similar lines to an upgraded car audio or a mobile phone hands free kit, maybe. I guess it is "Feet Free" kit :D

IF someone fitted a Cruise Control system to work as a hand throttle (which it won't in fact, anyway) due to some disability, say, then THAT would have to be declared to an insurance company, but in terms of driver disability aids. It is not something I had considered, but may make an (anonymous :) ) call out of interest.

Anchorman makes an interesting point about tyres and using different tyres to those that are OEed - I wonder what the official line is on that? I guess because it is such a widespread and expected practice, that as long as the tyres are fit for purpose on the vehicle, that is acceptable?

I would be VERY wary about making a 4WD to 2WD conversion and not informing an insurance company as that change DOES has a significant impact on the way the car will perform on the road in terms of handling in certain conditions and if any accident claim was due, I would amazed if an insurance payout was at best reduced as making that undeclared mod could be deemed to be partially responsible and at worst the insurance voided.

IMHO, I think carrying out this mod without first at least sounding out the insurance situation would be a little silly ;)

[anchorman]

Most car manufacturers do their homologation with 2 different tyre types. This gives them some flexibility to use either rather than stop productionif one supplier dries up for some reason - they tend to do it with friction material as well. It would be interesting to see what would happen if they couldn't get Bridgestone run flats! Sometimes the reasons are not so obvious for failure to supply. A manufacturer may not be able to get raw materials (although he will have two sources if he wise) or he could have a bad batch etc. Tyres and friction materials are heavily dependant on world supplies of oil and steel (interestingly, friction materials often contain ground up tyre [rubber crumb] as a filler or noise suppressor).

If some kind of accident were to occur where the suitability of the tyres came into question then it is up to the tyre manufacturer to come up with some test results to demonstrate that their product is fit for purpose. In this case when a third party manufacturer comes up with a general purpose tyre he cannot just sell it in the market place, he has to put it through a series of "worst case tests". In other words it will be tested at the highest weights and fastest speeds etc that the tyre would be subject to if fitted to a typical vehicle and there is usually a margin of overload. In friction materials these are called Regulation 90 tests but they may be called something else on tyres - maybe Bridgestone Kirk may comment.

If Toyota were asked to comment on how a third party tyre would effect the behaviour of one of their vehicles they would rightly state that they have no experience or test results of those conditions. For "regular" RAVs the suppliers are Bridgestone and Toyo.

[bothwell_buyer]

The early 4.1s are 4 wheel drive but just don't have the diff locked unless you choose. IE the 4 wheels have equal drive to each wheel. If a wheel loses grip then it spins and the resultant strain on the drivetrain will not be too healthy.

Example is when I do sprint standing starts, the front wheels lift off and the car then loses drive until the wheels drop down causing a bit of bounce. Using the diff lock keeps the 4 wheels turning without loss of traction to the back wheels and leads to less strain on the drivetrain. Outcome is faster launch times.

To muck about with the drivetrain is just going to put more strain on those bits you leave. Buy a front wheel drive car instead.

[bitman]

hmm, i had a look at those prop chafts and compared them between the 3-door and the 5-doors.

the 3-doors do have a litte play in them when try to rotate them by hand. but the 5-doors there isn't any play in at all, what i think isn't good. is this correct?

[anchorman]

hmm, i had a look at those prop chafts and compared them between the 3-door and the 5-doors.

the 3-doors do have a litte play in them when try to rotate them by hand. but the 5-doors there isn't any play in at all, what i think isn't good. is this correct?

I don't think I'd be too worried mate.

Were they both in "Park"? If so put them into neutral and try again. Even if after this there is still some backlash it is probably OK. The specification for backlash on the crown wheel is 0.13 - 0.18mm but there is no specification for rotational backlash.

If it isn't noisey or clunking on take-up I wouldn't worry.

[bitman]

no anchorman, it's the other way around. i think there should be some little play in it as the 3-doors has.

i think that the 5-doors is some thing wrong. this is the one with the horrible behaviour. it drives like if all diffs are in sperr mode. around corners it's strange feeling (heavy) in the steering etc. i personal think that there is some thing locked up. oh and yes, it tried both in drive, park and neutral. but no matter what position the gear lever is there isn't ANY play in... that's worrying me. but on the other hand the mpg was this week 35.4 mpg so the transmission isn't heavy.

[bothwell_buyer]

no anchorman, it's the other way around. i think there should be some little play in it as the 3-doors has.

i think that the 5-doors is some thing wrong. this is the one with the horrible behaviour. it drives like if all diffs are in sperr mode. around corners it's strange feeling (heavy) in the steering etc. i personal think that there is some thing locked up. oh and yes, it tried both in drive, park and neutral. but no matter what position the gear lever is there isn't ANY play in... that's worrying me. but on the other hand the mpg was this week 35.4 mpg so the transmission isn't heavy.

see! ah telt ye - the 5 door rav is un-balanced! try taking a door off an see if it helps?

[anchorman]

Bitman

Take the shaft off and see whether it is the front or rear diff' that has no backlash. Unlike the manual gearbox the automatic has a limited slip centre differential and there will definitely be some resistance at the front diff. The trouble is quantifying whether the 5 door has too much resistance or the 3 door has not enough without stripping the diff and checking the multiplate clutches.

In this diagram you can see the transfer assembly and I have marked the combined planetary gears for the front and rear diff' combination in blue, the limited slip multi-plate clutch in red and the transfer pinion in green. My info on the automatic transmission is very limited so I can't give you any values but you might get them from the Toyota Techdocs website.

Regards

[bitman]

thank you so much anchorman! perfect!

will have a look at it.

[anchorman]

Hey Bitman it might be a good idea to change the oil in the transfer box if it hasn't been done for a long time.

Regards

[bitman]

shouldn't that been done with those (expensive mr.t) services we do every 10k?

well thinking about it. if i use the car on a monday morning all is fine till after some miles . since i don't use the vehicle in the weekend all make

sense.

that picture was for me and now i can tell them (since it's still under warranty) where to look for!