Diff RATIO for running 34" simex?????HELP

[4.42doormangierangie]

Morning all,


I need to know what diff ratio is best running for 34" simex, also as i have a maxi drive rear diff do i need to get anything made for this diff in order to fit a new diff centre or can i fit the new gears without modifying the maxi too much????

I'm tunning the new inlet manifold with mild cam and truck avenger carby and finding that we are struggling with the current ratio's.


cheers simon

[GRIMACE]

IMHO the standard gearing should be fine.
Exspecially if you have a slightly tuned motor.

This is ofcourse my opinion only and I knwo of many people who think totally opposite.

[Slunnie]

4.11

[Petes]

I reckon you will be fine aswell with the std ones

[Slunnie]

But the question was what is the best.

The difference will be about 20% in the ratio between std tyres and the 34" Simex.

There is about 15% difference between standard 3.54 diffs and 4.11 diffs.

[Petes]

teh gearing is a bit better I agree but the fact the 4.11's seem to be weaker than the standard onesrules them out for me

[GRIMACE]

teh gearing is a bit better I agree but the fact the 4.11's seem to be weaker than the standard onesrules them out for me

not to mention cost...

Current = $0
4.11s = $1000

[Petes]

Followed 2 weeks later most likely by

Replacement set of 4.11's = $1000

[PacMan]

Hi 4.42doormangierangie,

i had 35" simex with bw35 automatic lt95 transfer case and 3.54 diffs.
The engine was a old 3.5 carby with new heads.

The car was absolutly useless with 35".
On road was a drama.
Off road was ok for easy terrain but not for steep hills.
Low range was to slow for bush roads and high range was to fast.
It's nothing left of that crap drive train in my Rangy.

I would go the 3.9 ratio from KAM in your case. There are the strongest setup for a rover diff.

If your problem is only the high range ratio, than change just the transfer case. A Defender transfer case has a lower high range than a Range Rover/Discovery. ~1.4:1 vs ~1.2:1.
It is a easy swap, you just have to change over your park break and gear stick setup.

That is only my car - maybe my engine was weak or the auto took a lot of power. Your engine should be ok for 3.9 ratio.


Greetings
Chris

[Slunnie]

Followed 2 weeks later most likely by

Replacement set of 4.11's = $1000

From what I've seen and read they are the same as the 3.54's due to better materials despite the smaller pinion.

Apparently the new 4.14's are meant to be heaps stronger than the 4.11's again. I think they are a 7 tooth pinion.

Then again, if you want best in a rover, then you'd be grovelling for 4.3 ratio Hi9's

[lokka]

For starters what gearbox/transfer are you running ?

If its the LT95 34's with a 3.54 diffs it will be fine in low range tho in high range you may find the gearing a tad too tall tho it may be ok and having the extra HP i doubt you will have a worry .

If its a LT230 the 3.54 diffs it should be much the same and in both cases you wont get any lower low range unless you do change CW&P and in my opinion if you do this dont bother with rover diffs do a toy conversion and sell what you have to get some funds back ..

I would tune it and then drive it for a few weeks and see how it is and if you find the gearing to tall in high range change the final drive ratio as there are plenty to chose from for both transfer types .

I ran a LT95 with .996 to 1 final drive in high range with 3.54's on 33's in my old rangie and i had a tired old 4.4 pushing it and it was great i also had it running on a holly but not the avenger it was one of my doctored 2bbl jobs the thing would pull the ton no probs and accelerated well enough to keep the doof doof rice burners on there toes

[4.42doormangierangie]

the 4.4 has heaps of pull, its a very fresh motor internally. The reason for the engine mods was to stop the dropping of fuel on steep inclines.

so the engine is fine, the gearbox is the original 4 speed Cant remember the code its a 76 2 door, in low range it pulls like a freight train but in the higher gears it loads up the engine something fierce and i was thinking that if i changed the current ratios that i may improve the load on the motor.

it doesnt help the inlet manifold is designed to work above 3500-5000rpm and the motor just doesnt want a bar of it. im hoping with a bit more fine tunning it will be satisfactory as its designed for the bush on the road.

simon

[PacMan]

Hi,

looks like you have a LT95 gearbox/transfer case.

You can get this box with lower ratio in high range, depends on what you already have.
This would be the cheapest way to get out of it.

Changing ring&pinion is more expensive but it will be a stronger setup at the end and improvment in low range.

But i think even better is what lokka wrote. Toyota conversion. But $$$.


Thanks
Chris

[lokka]

Sounds like you need to get the high range gear set from a county spec LT95 it will swap straight in to your box and can be done in situ under the rangie .

Your box could have either .996 to 1 or 1.1 to 1 high range if you swap to the county 1.4 to 1 problem solved

As for swaping ratios in the diffs if you do this with rover diffs it will be weaker as the 3.54 is the strongest rover CW&P if you want real strength here fit toy's

[jbell]

I run 4.75's from great basin rovers in the u.s. with 35" bfg krawlers
& have'nt had a problem in 2 years.
Plus with a good aussie dollar the price would be good too.
I run these on my healthy 3.9 auto lse with a detroit in the rear
& arb in the front.
GBR do other ratio's to that may suit your set up better.


Jeff

[swamp]

I agree with LOKKA 3.54 gears are the strongest, I have previously been flamed for this with people saying that 4.11 are as strong and some 4.75's are stronger.
The beauty of 3.54 gears is they are as strong as any aftermarket gears plus or minus 10% and if you break a set they are only a two hundred dollar replacement. As opposed to the $1000 + for installed aftermarket gears.
If after market gears are 10% stronger in my opinion they aren't worth the 500% increase in price.
Second hand 3.54 centre max $200 install your locker yourself ( not that hard) and your away again.
I also have some lt95 high range gearsets available, I can chase up the ratios if you are interested.

e

[roverbeau]

I have 3:54s in my ute with a holden 5lt and auto and last week striped the pinion teeth taking off from my house. I was going to put 4:11s into make up for the 35s on the road cause it gets a bit slow in the hills. But now it sounds like they are to weak. Would pegging the diffs help.
Beau.