Changing gearing for 35s?

[noogie]

Hi all

I want to run 35s one day but I want to make sure my gearing is all ok so as not to damage my drive train.

I've been told I need to change my diff centres (to 4.11's i think) and I know that low range gearing needs to be changed.

The Ashcroft website sell the 1.667 gear set which is designed for running larger tyres and it changes your high range gears in the TC.

If I was to install these gears, does that mean I won't need to change the diff centres? If this was the case, then I would do this and instal reduction gears at the same time for low range crawling.

Also what would the effect be when running my 33s as the 33s will be on most of the time, and the 35s on for the occassional hard trip.

Ashcrofts don't sell the low range reduction gear set unfortunately, so my only options appear to be the maxi drive set from MR automotive or the under drive which is just too expensive.
Does anyone know if you can source reduction gears from the UK?

Your ideas would be appreciated.

Cheers
Mick

[isuzurover]

You can do it that way, however 1.667 gears and 33's would suck on the road, and there may be some issues having a low case built for a 1.667 case - MR Automotive are the only company making the 30% and 50% reduction gearsets AFAIK.

1.411 Defender gears (and standard diffs) will be fine for 33's and low range will still be OK.

[clive22]

Hi


If you are running 35 for hard day trips only and 33 otherwise, I would change only your low range gearing via the 30% MR reduction gears.

With stock high range and on the 35s you can sit in 4th in lieu of 5th (wear that gear instead of 5th for a change) if its hilly or headwinds, but if you lower the high range you can't change up to 6th when running 33s

30% reduction are the go when running 35s, the extra control torque burst you can put on over steps, rocks really does help.


Clive

[noogie]

So I wont need to change diff ratios to 4.1?
Just do the reduction gears.

Won't driving on standard 3.54 ratio with 35s be harder on drivetrain?

[clive22]

Nope. If you're just doing day trips I wouldn't bother. If you're touring on 'em change the ratios, but hardly anyone tours on 35s for good reasons.

4.1's are weaker an issue with the front and more expensive too, especially $$$ for the sals.

Just stick it in 4th that's what I do. 4th is 1:1 which is direct and so strongest anyway. Don't labour in 5th no mater what tyres you're running, labouring is labouring.

The only problem this set up is low range and high range don't overlap so much so you have to shift from one to another which you can do on the fly <8km/h

High first may be too high in some circumstances as well forcing you into low range.

Clive

[Tusker]

Nope. If you're just doing day trips I wouldn't bother. If you're touring on 'em change the ratios, but hardly anyone tours on 35s for good reasons.

4.1's are weaker an issue with the front and more expensive too, especially $$$ for the sals.

Just stick it in 4th that's what I do. 4th is 1:1 which is direct and so strongest anyway. Don't labour in 5th no mater what tyres you're running, labouring is labouring.

The only problem this set up is low range and high range don't overlap so much so you have to shift from one to another which you can do on the fly <8km/h

High first may be too high in some circumstances as well forcing you into low range.

Clive

4.1s maybe. 4.11s are better. They are a different tooth count. And check before you install. I ordered a 4.11 and it was a 4.10 that was delivered.. caused problems for a while.

To the OP, you don't say what the rest of your running around is. If it's your daily driver, go the 4.11s, much easier on the clutch in daily driving. They'll pay for themselves in clutches soon enough.

If it's a weekend warrior, then the rockcrawler gears will probably have more appeal.

I'd forget the 1.667s too. They are very old, designed for the underpowered cars pre Tdi days. Very seen them or used them, but they may give problems.

And don't forget you need dual speedo correction..

Regards
Max P

[noogie]

Nope. If you're just doing day trips I wouldn't bother. If you're touring on 'em change the ratios, but hardly anyone tours on 35s for good reasons.

4.1's are weaker an issue with the front and more expensive too, especially $$$ for the sals.

Just stick it in 4th that's what I do. 4th is 1:1 which is direct and so strongest anyway. Don't labour in 5th no mater what tyres you're running, labouring is labouring.

The only problem this set up is low range and high range don't overlap so much so you have to shift from one to another which you can do on the fly <8km/h

High first may be too high in some circumstances as well forcing you into low range.

Clive

Thats what I thought in the first place.
Cool. The crawler gears will be awesome running the 33s also.

When you say "high first is too high and it can force you into low range" , do you mean it'll go into LR on its own when taking off?

Also why wouldnt I go the 50% gears over the 30% ?
Ive been told the 30% gears are stronger.

[clive22]

Hi


Mines a V8 and yours is a TD5, so i have no turbo lag.

But when your doing 3 points turns up hills, out of gutters you do notice the loss of torque. It's OK really, but you do have to be mindful of over slipping the clutch.

I went 30% reduction I think strength wise there both unbreakable, but you do excavate the case to make room for the gears leaving that wall quite thin.

For me 50% would have been too low. I think the 50% gears are aimed at auto trans drivers.

Anyways stick your car in low range take it to max comfortable speed to yours ears and seat and multiply be two thirds and that will be your top speed with 50% reduction. Add 10% to that for max speed with your 35s.

Its three quarters for the 30% reduction gear.


Clive

[noogie]

Ive been told the reduction gears can be noisy.
What are others experiencing?

I was also told that there is a uk supplier of reduction gears. Does anyone have an idea who that might be?

[isuzurover]

Ive been told the reduction gears can be noisy.
What are others experiencing?...

Yes they whine as all straight cut gears do. Quite noisy in 4th and 5th low but otherwise unobtrusive. It is similar to the low range whine in a series landie if you have ever driven one.

Ashcroft used to make an 80% reduction, however they weren't popular compared to the ashcroft underdrive and/or may have suffered some failures so are no longer made.

[noogie]

I've been advised to just change diff ratios to 4.1.1. as this will bring gearing back to normal when 35s are on and downhill gearing will also improve.

Also less stress on drivetrain.
However on 33s she will Rev higher just how much this will affect fuel economy isn't clear but apparently the engine will be running more efficiently.

Has anyone just done the diff ratios and found it OK when running the smaller tyres and what it's like running 35s downhill.