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help wtd reducing high speed revs in 1.0 sj40 4spd
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Author:  sstteevvee [ Wed Apr 06, 2011 2:02 pm ]
Post subject:  help wtd reducing high speed revs in 1.0 sj40 4spd
Hi guys

I've been trying to do some research regarding the easiest way to reduce the revs on a 1L sj40 over long distance driving. I did come across a site somewhere that said swapping the transfers to 1.3l ones would reduce revs by about 10% but i just cant find that site anymore.

In all my searches i've come across engine conversions threads but i'd be happy to leave the 1.0L in there as long as i can drop the revs somewhat, i understand this will affect low range too but the main 4x4 it sees is soft beach sand so it shouldn't be too much of an issue.

The main goal would be to have the 1.0L sit on 100 to 110km/h without worrying about a piston ejecting itself.

Thanks
Steve
Author:  Ben_Sierra [ Wed Apr 06, 2011 2:40 pm ]
Post subject:  Re: help wtd reducing high speed revs in 1.0 sj40 4spd
What revs does it do?

4000 or so would be nothing to worry about...

The easiest way to drop the revs would be bigger tyres...
Author:  honks [ Wed Apr 06, 2011 7:24 pm ]
Post subject:  Re: help wtd reducing high speed revs in 1.0 sj40 4spd
as ben said bigger tyres would help when i went to 215/75's on my 1.3 sierra the revs dropped by a couple hundred rpm on the high way but then again you might feel bigger tyres a bit more in the power department with a 1 ltr.
Author:  sstteevvee [ Wed Apr 06, 2011 11:53 pm ]
Post subject:  Re: help wtd reducing high speed revs in 1.0 sj40 4spd
Hmmm yea i dont know how the 1.0l will respond to bigger tyres. Its currently on 205/75 15's. Would the addition of extractors and an air filter like a pod filter help the little screamer to "breath" better? I know its not going to lower revs but do they make any difference on the 1.0l?
Author:  sstteevvee [ Wed Apr 06, 2011 11:56 pm ]
Post subject:  Re: help wtd reducing high speed revs in 1.0 sj40 4spd
Forgot to add that i dont currently have a tacho in it at the moment but its on my to do list in the very near future. I'm going to do a search but does anyone know where i have to hook it up to? or even which tacho suits the 1.0 best?
Author:  Reubs [ Thu Apr 07, 2011 2:01 am ]
Post subject:  Re: help wtd reducing high speed revs in 1.0 sj40 4spd
sstteevvee wrote:
Would the addition of extractors and an air filter like a pod filter help the little screamer to "breath" better? I know its not going to lower revs but do they make any difference on the 1.0l?

Extractors might help, but aftermarket air filters aren't going to make any noticable difference and are a PITA IMO.

Why do you want to reduce highway RPM? I don't own a 1L but I own a 1.3 and 1.6 Sierra and know that they are already slowed by a headwind at 3600-4000RPM. If you were to make your gearing steeper a headwind or a hill is only going to give you more problems. RPM is a factor in the power equation. Less of it means your highway driving won't get any better. Also if you are worried about engine noise, road noise from the rest of the car is more noticable when highway driving IMO.
Author:  tanshi [ Thu Apr 07, 2011 2:10 am ]
Post subject:  Re: help wtd reducing high speed revs in 1.0 sj40 4spd
Swapping to a 1.3 transfer case will take you from 1.580 : 1 in high range to 1.409 : 1

you could also swap to a coily transfer i suppose which would take you to 1.320 :1

another option would be to pick up a set of nt 1.3 diffs and swap them in giving you 3.9 diff gears and the option of 3.7s

the diffs would also give you stronger cvs in the front diff.

there are heaps of options. but realistically 1 litres love to rev.

A mate has a one litre in an LJ and it regularly sits at over 5-6 grand on long trips i believe
Author:  lauby [ Thu Apr 07, 2011 2:22 am ]
Post subject:  Re: help wtd reducing high speed revs in 1.0 sj40 4spd
Author:  sstteevvee [ Thu Apr 07, 2011 2:48 am ]
Post subject:  Re: help wtd reducing high speed revs in 1.0 sj40 4spd
Thanks for the info. I see the point about the rpm to power ratio. I've been doing a fair bit of searching between here and another zook forum and although maruti boxes are rarer than hens teeth it may be the best option to look for a 5 speed. Theres a couple of really good threads on how to do the conversion around, this option will still allow me to drop to 4th on hills etc...

I didnt realise that these little 1.0 were that happy to rev, they just seem to make alot of noise when doing so which is what was concerning me.

As far as the dash goes mine is a full metal one with a different cluster so i have to add a little aftermarket tacho
Author:  2stroker [ Thu Apr 07, 2011 2:58 am ]
Post subject:  Re: help wtd reducing high speed revs in 1.0 sj40 4spd
Any aftermarket tacho will work as long as it is for a 4stroke 4cyl engine. 5 speed is the best option but as you already know hard to find, they can be built up from a combination of parts from a late model 1 litre 4 speed and a 1300 5 speed
Author:  shakes [ Thu Apr 07, 2011 3:42 am ]
Post subject:  Re: help wtd reducing high speed revs in 1.0 sj40 4spd
Depending where in the rev range your sitting lowering it may actually be worse for the motor.
Author:  sstteevvee [ Thu Apr 07, 2011 5:43 am ]
Post subject:  Re: help wtd reducing high speed revs in 1.0 sj40 4spd
Thanks for the info guys. Seems like alot of you know your stuff!! I'm currently on the look out for a smallish tacho preferably within the 3 inch range so if anyone has any suggestions go nuts
Author:  Ben_Sierra [ Thu Apr 07, 2011 6:35 am ]
Post subject:  Re: help wtd reducing high speed revs in 1.0 sj40 4spd
sstteevvee wrote:
Hmmm yea i dont know how the 1.0l will respond to bigger tyres. Its currently on 205/75 15's.


It doesn't matter how you achieve the gearing change, be it tyres, diff or transfer gears, the performance effect will be identical...
Author:  Daz7 [ Thu Apr 07, 2011 6:58 am ]
Post subject:  Re: help wtd reducing high speed revs in 1.0 sj40 4spd
sstteevvee wrote:
Thanks for the info guys. Seems like alot of you know your stuff!! I'm currently on the look out for a smallish tacho preferably within the 3 inch range so if anyone has any suggestions go nuts


Get a tacho (any 4cyl aftermarket tacho will work) but the 1 litre's are screamers compared to the 1.3's.

Forget the pod filters and the like, they'll give you noise that might sound better but bugger all performance benefit and any sort of gearing change will just make the thing slower on the hills.

From memory my old LJ80 and 1L Sierras were more than happy sitting on 5000rpm day in day out.
Author:  Gwagensteve [ Thu Apr 07, 2011 8:44 am ]
Post subject:  Re: help wtd reducing high speed revs in 1.0 sj40 4spd
With everything stock, you're revving at about 5100rpm at 100km/h.

There's a reason that suzuki geared them that short - put some 31's on the car and you'll be still running 4200rpm @ 100km/h, and it will struggle on hills and in every other gear.

Part of the problem with 1.0 litres is the very tall 1st gear - 3.0:1. If you gear the car taller overall you'll be hating the clutch when heavily loaded or on steep hills, even on road.

The real solution is the super carry 5 speed gearbox. They typically have a lower 1st gear AND an overdrive. That's a win-win, assuming you can actually can pull a 5th gear on the highway. I doubt it if you have any load or a headwind, I bet you won't.

Steve.
Author:  LittleJeep [ Thu Apr 07, 2011 9:40 am ]
Post subject:  Re: help wtd reducing high speed revs in 1.0 sj40 4spd
if you want a lower 1st gear, get hold of an LJ80 gearbox, i think they are 3.8:1, you can swap the shifter housing on the back to a 1L and it will bolt straight in!
Author:  sstteevvee [ Thu Apr 07, 2011 10:28 am ]
Post subject:  Re: help wtd reducing high speed revs in 1.0 sj40 4spd
The first isnt my main concern. The top end i.e 4th/5th is. Would like to have the option to slot it in 5th along nice long flat roads rather than screaming in 4th.

From what i can gather i'll have to be on the look out for hens teeth in order to get a 5th gear
Author:  303zuke [ Thu Apr 07, 2011 11:20 am ]
Post subject:  Re: help wtd reducing high speed revs in 1.0 sj40 4spd
Another option is an Electric Overdrive. I had a Laycock O/drive in an '82 1.0lt. It replaced the jackshaft between the gearbox and transfer case and gave an O/D on all gears and t/case ratios, in effect a choice of 16 forward gears! It was electrically switched at any speed (synchro) by a button on the dash, had plans to fit a switch on the gear lever. A bit of a discussion here.

The Laycock overdrive was fairly common in UK made cars of the 60's and 70's and are still available from the UK on E-bay. They were available on plenty of cars in Aust, including the Volvo 240. They're made by GKN these days and are the unit used in the States by Gear Vendors in their overdrive for F350 Fords and Chev C3500 trucks, so you wont stress it out in a little 1.0 Sierra.

Brand new

Used

One for sale in the States, and a Typical GV aftermarket kit.

They're easy enough to find, just have to convince them to ship/post to you!!
Author:  Gwagensteve [ Fri Apr 08, 2011 11:09 pm ]
Post subject:  Re: help wtd reducing high speed revs in 1.0 sj40 4spd
sstteevvee wrote:
The first isnt my main concern. The top end i.e 4th/5th is. Would like to have the option to slot it in 5th along nice long flat roads rather than screaming in 4th.

From what i can gather i'll have to be on the look out for hens teeth in order to get a 5th gear


I think you've slightly missed my point about first gear.

1.0 litres run short transfer ratios and short diff gears so that the engine does rev high at highway speeds to match the torque and HP curves of the 1.0 litre motor.

If you raise transfer or diff ratios in order to lower highway revs, you'll make your already tall first gear even taller, making the car difficult to drive.

If you use a super carry 5 speed, you also get a lower first gear (along with the 5th gear) allow ing a much better choice of ratios overall.

Another option is to find a type 3 1.0litre 4 speed. These are internally a 4 speed version of a 1.3 gearbox with a 1.0litre bellhousing - a 1.3 5 speed gearset and tailshaft housing can be bolted in. giving you a 1.0 five speed.

I'd be doing the following experiment before I started research/spending though:

Borrow a set of 31" tyres from someone, and a GPS. Put the 31's on (they don't need to clear very well - only enough to drive down the road - put them only on the back if necessary) and drive down the road at a GPS correct 100km/h. I bet your car will struggle to hold speed. If it can't hold speed as it is now with the taller gearing of 31's - it won't pull a 5th gear so save your money.

Suzuki set the 1.0 to spin 5100rpm at 100 for a reason. If it could have pulled 100 at 4200rpm, that's how they would have set it up.

Note also that NO 1.0 sierra - even marutis- ever ran a 5 speed. I don't think they have the torque, but the experiment above will prove it.

Steve.
Author:  sstteevvee [ Sat Apr 09, 2011 4:00 am ]
Post subject:  Re: help wtd reducing high speed revs in 1.0 sj40 4spd
Thanks for the post steve. Some informative reading there. I guess what it comes down to is how happy are the f10a's to sit at those types of revs? I want to be able to drive at round 100, or a lil less if need be for a solid 1.5 to 2 hours
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