[kd883]

Hi guys,

I'm new here. I drive a 1994 WT Sierra, 1.3L, which has 2" OME springs, extended shackles and 30" Maxxis Bighorns.

The Sierra is my daily, and I love driving it both on and off road.

The only thing that bugs me is highway driving. The missus and I love going to Stockton for the weekend (from Sydney) but the 2.5 hour drive is painful.

I have been reading up on both reduction gears and the 1.6/gti engine conversions as possible solutions. I understand the engine conversions well enough, having done a few in the past, but the gearing thing is doing my head in. I understand the principle, but there seems to be so many options! Can someone please help me out a bit here?

My current set up (as I bought it) is 30" Bighorns on standard Sierra rims, with 2" OME springs and extended shackles. Sadly, these Bighorns scrub severely on the springs at full lock. How can I fix this? Are aftermarket rims a possible solution? I don't understand how the whole 'offset' thing quite works...

Lastly, my Sierra is a softop with a fibreglass hardtop. Is there any way of fitting roofracks to this kind of set up?

Any thoughts, opinions or wisdom would be greatly appreciated.

Cheers!

KD.

[rpmwrx]

Welcome to AZ KD,

Getting your gearing right is one of the most satisfying mods you can do to a sierra. Most of the crew on here have sourced their reduction gears from lowrange offroad in the usa. They stock a huge range of gears. Best to get on there and have a good read. With your current suspension mods you should be able to fit 31's no probs. Here is a table off lowrange offroad.


http://www.lowrangeoffroad.com/index.ph ... -case.html

You also need to beef up your mounts and possibly weld in a roktoy ring so the soft alloy transfer casing doesn't rip itself to bits under the extra torque generated by the reduction gears. I'm also a big believer of not only having transfer case gears, but also having diff gears as well, so all the gearing reduction isn't in the one spot. But this is only really necessary when running bigger tyres.

As far as ride quality goes, there's not alot that can be done as it is a short wheelbase. You can try removing a leaf from each pack to soften up the ride. Ideally a 45 degree shackle angle is ideal. Fitting aftermarket seats is a good step to added comfort as well as benefits when your offroad.


With your tyres rubbing on the rims i'd suggest you simply adjust your driving style so it doesn't rub. You will need a huge offset to acheive no rubbing on the springs, which isn't very practical when it comes to wheel bearibg longevity.

[abclarke]

My 31x10.5xr15 bighorns rubbed a bit on full lock, so i went out and got some -13 offset king steelys and now they just rub SLIGHTLY. But i also spun around the spring clamp bolt so the threads on the inside, reducing where the tyre rubs.

[kd883]

Thank you for your comments guys, much appreciated.

I have had a look at lowrangeoffroad.com - seems like a great resource. Are their prices reasonable? Their products seem to be high quality. Are there no stores in Australia like this?

Going by that table, it seems that the 4.9:1 would be the best option. How do they measure these ratios? What do they mean?

According to the website, 4.9:1 with 30" tyres will give me a 16% reduction in high range. They advertise this as 'getting your fifth gear back'. How beneficial will this be to highway driving? Will I be able to comfortably sit on 110km/h? I find that I can sit on 110 km/h at the moment, but the slightest incline puts me back into 4th straight away, big hills back to 3rd doing 70 km/h.

abclarke - great idea! I've thought of doing that before but was unsure if it would make much difference. Glad to hear it was successful for you. Will definitely try it myself now.

rpmwrx - what do you mean by 'beef up the mounts'? Also, please forgive my ignorance, but what is a roktoy ring?

In fitting these reduction gears, is any pressing required? Or is it a straight forward swap-over type job?

I've noticed 31" tyres to be more common than 30". Are there any other advantages to this apart from the extra 0.5" lift?

Thanks again fellas - sorry I know there's heaps of questions there. Anything you can help with would be greatly appreciated.

KD.

[rpmwrx]

You will be hard pressed to find better prices than lowrange... especially with the high ozzy dollar at the moment.

Another option that is worth considering is swapping in a transfer case from a 1.0L Sierra. This is probably the best bang for buck option for your setup.

I think what would be a good idea is for you to hook up with a local zooker who has reduction gears, so you can experience them for yourself. They give so much control.. They are awesome

This is a roktoy ring...



And this is a mighty kong transfer cradle with welded in roktoy ring...







I was running solid alloy mounts for a while because I kept ripping rubber mounts in half. I've just swapped over to some spidertrax poly mounts, but i'm yet to take it offroad and test it yet, but they are supposed to be a good thing, so it all should be ok. Most guys on here just run with the standard rubber mounts and when they break, they just swap them over, but i wanted a better solution for this... Just Cruizin on here does a poly mount kit that also lifts the transfer case up above the chassis rail...

Hope all that helps...

Ross

[jdk81]

First of all, a bit more info please. What type of tracks are and you driving now, and what would you like to drive later. What is your budget like?

Do yourself a favour and remove the extended shackles, extended shackles arent the best idea.
Massage the wheel arches, do a guard chop if needed (guard chop is flavour of the month and better option imo than body lift). If the guard chop isnt an option, consider 2" body lift.

I would consider making vertical supports inside the canopy (aka roll bars) and drill some holes through the canopy for the roof racks to attach to. You can do it externally, but will look uglier than a hat full of arseholes.

As per scrubbing, get -13 offset.

31s are more popular because they are that bit bigger, and more common, often cheaper due to popularity.
I personally dont like 31x10.5 because of the width, for some reason I knew what I wanted and I still ended up getting 31x10.5 to save some money. I have regretted it since.

With bigger tyres, remember you need bigger brakes. So buy yourself some vitara lwb vented rotors and calipers.
Also ensure your brake lines arent being stretched.

Consider doing diff gears, this reduces load on the drive train and also corrects the speedo.
Diff gears are the best option imo, but not the cheapest/easiest which is why people dont like them.
4.6 diff gears from front of a 3speed auto vitaras would be my first choice, then select what xfer suits you later on when you need it.
Once diff gears are in, it makes choosing xfer gears tougher, because you have to make more sacrifices (carrying higher revs on the highway).
A lot of all the extra "beefing" up of stuff is needed because diff gears arent done, and people drive really harsh.
Keep rubber mounts, something cheap and easy to replace is ideal. Going to solid mounts means something else more expensive and/or harder to fix will break.

There issue with modding, is it is not that easy and simple as one mod etc, they all seem to snowball.
People have their own opinions, and the flavour of the month changes.
Various people are still stuck in the 70s, 80s, 90s, 00s.

Just because it is popular, doesnt mean its correct. Going against the majority and trying a different setup is how the flavour of the month changes.

[kd883]

Thanks very much jdk and rpm.

Great idea jdk with the internal 'rollbar' type supports for the roof racks. Have you ever seen this done?

I currently drive some mildly rocky/steep tracks when I can find them. I thoroughly enjoy the challenge of these sort of tracks - determining the best line for traction and seeing how effective this is in practice is very rewarding. I also enjoy driving through muddy tracks and water crossings, as well as the endless sand dunes of Stockton Beach. I don't plan to do anything too extreme in the near future, but the thrill of a new track is always fun. My budget is limited sadly, but I find I generally get most places with the setup as it stands, (I just have to pick the right 'line', which sometimes takes a couple of attempts).

Why are extended shackles a bad idea? Also, why have only so few Sierras had the 'spring over' conversion?

What is the advantage of the 1.0L transfer case?

Is it possible to fit air-conditioning to a Sierra?

KD.

[jdk81]

kd883 wrote:

with the internal 'rollbar' type supports for the roof racks. Have you ever seen this done?

No, I havent seen it personally, but theres heaps of rollbars about.
Remember, they arent rollbars they are roof rack supports.
Its a neater option, the only downside is the 4 holes drilled into the canopy (which may devalue it a little). I will be doing it in the future.

kd883 wrote:

Why are extended shackles a bad idea?

On stock or 2" lift front springs, they change the geometry of how the spring works. Pretty much gives a harsher ride, and reduce castor.
However they are useful when used in the correct application i.e. ruf etc

kd883 wrote:

Also, why have only so few Sierras had the 'spring over' conversion?

I dont know from experience.
However, a SPOA is difficult to get correct.
SPOA is mainly done when installing lux diffs. It used to be done to get more lift and strength, and use the lux diff ratios.
However, it not really cool anymore. These days people are more educated.
Theres CrMo axles available for strength, and diff gear and transfer gears available now too.
Guard chopping (virtual lift) is the go.
Keep it low and stable.

kd883 wrote:

What is the advantage of the 1.0L transfer case?

It has lower ratios than the 1.3 case, which helps correct gearing.

kd883 wrote:

Is it possible to fit air-conditioning to a Sierra?

Yes, start looking for parts.

kd883 wrote:

I currently drive some mildly rocky/steep tracks when I can find them. I thoroughly enjoy the challenge of these sort of tracks - determining the best line for traction and seeing how effective this is in practice is very rewarding. I also enjoy driving through muddy tracks and water crossings, as well as the endless sand dunes of Stockton Beach. I don't plan to do anything too extreme in the near future, but the thrill of a new track is always fun. My budget is limited sadly, but I find I generally get most places with the setup as it stands, (I just have to pick the right 'line', which sometimes takes a couple of attempts).

Budget dictates most decisions. To be honest, you can keep using it as it whilst you save. Worst case scenario you will go through clutches a bit quicker.
As per gearing, its up to you to choose. A 1.0L xfer would probably be the cheapest option and give you a bit more versatility.
Whilst you decide what you want out of your car.
Remember, what is popular isnt always whats right for you.

[shep]

seeing as you use your car as apposed to being a weekend toy car driver there are a few things i would avoid with the main one being
a 45deg shackle angle. well go for a 45deg angle if ya like them inverting every time ya go for a trip anyway.

i think the best advise for people building cars is unless ya live in vic dont listen to someone that does cos they are strange.

[jdk81]

shep wrote:

seeing as you use your car as apposed to being a weekend toy car driver there are a few things i would avoid with the main one being
a 45deg shackle angle. well go for a 45deg angle if ya like them inverting every time ya go for a trip anyway.

I am not really sure what you are getting at, who said 45 deg, and 45 deg from where?

I know its jeeps but was a decent read. This google thing works alright.
http://www.quadratec.com/jeep_knowledgebase/article-93.htm

shep wrote:

i think the best advise for people building cars is unless ya live in vic dont listen to someone that does cos they are strange.

Thats a good point, and its not an insult because I am not a Victorian, I just reside here.
It's big country and its different all over. What is fantastic one region, will be not great in other regions.

Oh, and Shep go set fire to something.