Jump to content

changing the low ratio


Recommended Posts

I am currently running a 1.2 transfer box and am new to this malarky so please excuse my ignorance. I've heard you can change the low ratio in a transfer box without altering the high ratio? my reason for this is I have an auto box and it is carp at engine breaking going down steep inclines. is this possible? what do you need? and how do you do it?

cheers

Link to comment
Share on other sites

My Defender came with a military transmission which has a lower 1st gear than the standard issue trans. I subsequently had to replace the trans and used a civilian box for the rebuild and in all honesty the military box 1st was way too low, almost useless in most driving situations and the new civilian trans is much easier to pull away with from a standing start. Having said that I am sure if you need to pull a tank out of a ditch then that low 1st gear is useful but you have to weight up the pros and cons of such a set up for us civvies.

Link to comment
Share on other sites

I am currently running a 1.2 transfer box and am new to this malarky so please excuse my ignorance. I've heard you can change the low ratio in a transfer box without altering the high ratio? my reason for this is I have an auto box and it is carp at engine breaking going down steep inclines. is this possible? what do you need? and how do you do it?

cheers

Sorry if I'm teaching granny to suck eggs :ph34r:, but from my experience of driving an auto offroad there is neglible difference in engine braking. Are you locking it in 1st?

Link to comment
Share on other sites

Sorry if I'm teaching granny to suck eggs :ph34r:, but from my experience of driving an auto offroad there is neglible difference in engine braking. Are you locking it in 1st?

Unfortunate Ross there is quite a difference......... ;)

The typical RR ZF4HP22 auto box ratios are,

1st 2.48

2nd 1.48

3rd 1.00

4th 0.73

Where as the typical R380 manual box ratios are;

1st 3.60

2nd 2.11

3rd 1.40

4th 1.00

5th 0.77

So 1st in an auto is like 2nd (plus a bit) in a manual ...............

With a diesel it is not so bad…………… but with a petrol you really know the difference

Link to comment
Share on other sites

Change diff ratios or use a Borg Warner t-box and the Tomcat low ratio chain and cog set, think they lowered it by about 30%.

Or, just put up with it as it is, and learn to use the brakes.... :)

Link to comment
Share on other sites

Maxi-Drive make lower low ratio kits.  30% and 49% lower (4.3:1 and 5:1).

Seems not any more...

http://forums.lr4x4.com/index.php?showtopic=20265

You won't be able to change just the low box unfortunately, but then with bigger tyres you will want to drop the high as well, 1.2 on 35" tyres is going to play havoc with your fuel economy.... and make driving it on the road a very tiresome experience, with autobox changes all over the place.

Link to comment
Share on other sites

Seems not any more...

http://forums.lr4x4.com/index.php?showtopic=20265

You won't be able to change just the low box unfortunately, but then with bigger tyres you will want to drop the high as well, 1.2 on 35" tyres is going to play havoc with your fuel economy.... and make driving it on the road a very tiresome experience, with autobox changes all over the place.

am keeping my current tyres for the mo, have loads of other things to do first, was kind of jumping a gun a bit. so you can get an underdrive thing which will change my low but not my high?

Link to comment
Share on other sites

am keeping my current tyres for the mo, have loads of other things to do first, was kind of jumping a gun a bit. so you can get an underdrive thing which will change my low but not my high?

OK. To clarify... There are 3 possible routes.

1) Maxidrive low range gears. This changes your low ratio only. 30% or 49% lower. 4.3:1 or 5:1 instead of 3.3:1.

2) Fit an Ashcroft underdrive. When engaged, it added 2.69 times the current gearing. Thus 2.59*3.32= 8.9:1 low/low range. You then have 4 possible transfer case ratios. 1.4:1, 3.3:1, 3.7:1 and 8.9:1.

3) Fit lower range differential gears AND higher high range gears. If you change to 1.2 transfer gears and 4.1 diff gears, high range will be around the same and low range is 16% lower.

Link to comment
Share on other sites

I was curious about the Maxidrive gears, wanted to confirm they were still available, as I heard they were not, however:

Peter,

Thanks for your enquiry.

Yes we are producing the rockcrawlergears.

They cost A$2000 for a 30% reductionor A$2200 for 49% reduction.

This includes the cost of a newintermediate gear.

:)

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

 Share

×
×
  • Create New...

Important Information

We use cookies to ensure you get the best experience. By using our website you agree to our Cookie Policy