It is currently Tue Feb 25, 2020 6:04 am
Board index » Talking About Stuff » N00b Talk



Post new topic Reply to topic  [ 19 posts ] 
Author Message

Offline
User avatar

Joined: Mon Jul 08, 2019 10:27 am
Posts: 131
Vehicle: Suzuki sierras

Post Posted: Fri Sep 06, 2019 10:09 pm 
Reply with quote Top  
G'day, Im running 600 16 bar treads on lj rims under my sierra but was wondering if it is worth going to a 750 16? could you run 750 16s on lj rims or are they to narrow, and running 750 16s will i break running gear? I have a locker if that makes any difference and will hopefully be getting reduction gears soon.
Cheers Jack.

 Profile  

Offline
User avatar

Joined: Thu Feb 26, 2009 11:00 pm
Posts: 11418
Location: Melbourne

Post Posted: Fri Sep 06, 2019 10:30 pm 
Reply with quote Top  
7.50 is too wide to be legal/happy on a 4.5” rim. It’s a good size but a little annoying to fit as it’s a fairly tall tyre. (~31.75” when new)

_________________
hillbilly 2 wrote:
Gwagensteve is why auszookers will never be taken seriously

 Profile  

Offline
User avatar

Joined: Mon Jul 08, 2019 10:27 am
Posts: 131
Vehicle: Suzuki sierras

Post Posted: Fri Sep 06, 2019 10:41 pm 
Reply with quote Top  
Ok thanks gwagensteve what tyre size would you suggest on lj rims under a sierra or would you stick with 600 16s?
cheers Jack

 Profile  

Offline
User avatar

Joined: Thu Feb 26, 2009 11:00 pm
Posts: 11418
Location: Melbourne

Post Posted: Fri Sep 06, 2019 11:01 pm 
Reply with quote Top  
7.00 16 is pretty sweet.

_________________
hillbilly 2 wrote:
Gwagensteve is why auszookers will never be taken seriously

 Profile  

Offline
User avatar

Joined: Mon Jul 08, 2019 10:27 am
Posts: 131
Vehicle: Suzuki sierras

Post Posted: Sat Sep 07, 2019 9:14 am 
Reply with quote Top  
I'll look at some of them for my next set, would 6.5 gears be ok? so long as the car can do 90 i'd be happy.
Cheers Jack

 Profile  

Offline
User avatar

Joined: Thu Feb 26, 2009 11:00 pm
Posts: 11418
Location: Melbourne

Post Posted: Sat Sep 07, 2019 9:29 am 
Reply with quote Top  
I don't know who is perpetuating stories that transfer reduction gears reduce top speed, but I read it all the time and it's fundamentally wrong - not your fault Jack - it's like "suspension lift fits bigger tyres" and "suspension lift adds flex" and "shocks for a 2" lift" - they are falsehoods that the 4WD community can't get their head around for some reason.

Top speed of a stock sierra in good condition is plenty - it's around 125km/h. At that speed the engine's torque can't overcome wind resistance. I think that peak speed figure is achieved at around 4500 rpm in 5th which is where torque and horsepower curves intersect, so as revs increase torque is falling and wind resistance is increasing by a square law and the car can't go faster.

(interesting - it takes about 100hp to make a car go 100mph, 500hp to make it go 200mph, and 1600hp to make it go 300mph.... - my numbers are loose but you get where I'm heading)

nobody fits transfer gears with stock tyres. Transfer gears increase high range reduction which offsets the larger diameter tyres everyone fits.

For 6.5 gears that's about 17%- or cruise revs return to stock with 30.4" tyres. (So 31's) with a 7.00 16 at ~30" revs will be very slightly increased at highway speeds which will help to offset the increased aerodynamic drag of the taller tyre/car. There will be no meaningful effect on top speed.

Running a 30" tyre with no transfer gears causes a marked reduction in top speed because the car is now too tall geared and doesn't produce enough torque at lower cruise RPM to maintain speed, so 5th gear becomes useless, and you're back to buzzing along in 4th on any incline.

_________________
hillbilly 2 wrote:
Gwagensteve is why auszookers will never be taken seriously

 Profile  

Offline
User avatar

Joined: Mon Jul 08, 2019 10:27 am
Posts: 131
Vehicle: Suzuki sierras

Post Posted: Sat Sep 07, 2019 9:35 am 
Reply with quote Top  
Ok that explains it clearly how would you increase you high range revs so that you are doing 90kph in 5 gear at between 3600 to 4000 and have a decent low range?
Cheers Jack

 Profile  

Offline
User avatar

Joined: Thu Feb 26, 2009 11:00 pm
Posts: 11418
Location: Melbourne

Post Posted: Sat Sep 07, 2019 10:01 am 
Reply with quote Top  
That's easy - you need to swap to deeper diff gears like 4.57's or 5.12, but what's the requirement to be so deeply geared on road? if it's for towing or heavy loads, you're much better using 4th, which will give you almost exactly that outcome rather than loading up 5th, which isn't very strong.

_________________
hillbilly 2 wrote:
Gwagensteve is why auszookers will never be taken seriously

 Profile  

Offline
User avatar

Joined: Mon Jul 08, 2019 10:27 am
Posts: 131
Vehicle: Suzuki sierras

Post Posted: Sat Sep 07, 2019 10:08 am 
Reply with quote Top  
partly for towing but i know you shouldn't tow in 5th, but mostly because i never use 5th except for down hills and i never cruse above 90 so it would be nice to have the gears closer together.
Is it hard to fit ring and pinon gears and will they fit in with an air locker? thanks for all the help.
Cheers Jack

 Profile  

Offline
User avatar

Joined: Thu Feb 26, 2009 11:00 pm
Posts: 11418
Location: Melbourne

Post Posted: Sat Sep 07, 2019 10:34 am 
Reply with quote Top  
The car should pull 90 in 5th just fine. With slight overgearing with reduction gears I"m sure it would be no problem with stock diff gears. Then, when towing, you can use 4th at 90 and when not towing you can use 5th.

Spend LOTS of time with a gearing calculator like the one on grimmjeeper to understand what you're working with.

Changing diff gears isn't really a DIY job unless you have the tools required and know how to use them. IT's easy to get wrong an destroy gears. Yes, the will fit with an airlocker, but it's an expensive job. some ratios are easier to get than others

options are 3.9(NT 1.3) 4.1 (jimny, WT maruti) 4.3 (jimny, some GV) 4.57(aftermarket) 4.65 (auto carby vitara) 4.88 (gv) 5.12 (Vitara and some GV) 5.38 (US 1.3 litre vitara) and 5.7 4X4art aftermarket

but diff gears won't correct low range gearing, you'll still need transfer gears for that, and as they correct high range of bigger tyres themselves, that's normally enough. Diff ratio changes aren't generally required until you're over 33" tyres.

_________________
hillbilly 2 wrote:
Gwagensteve is why auszookers will never be taken seriously

 Profile  

Offline
User avatar

Joined: Mon Jul 08, 2019 10:27 am
Posts: 131
Vehicle: Suzuki sierras

Post Posted: Mon Nov 04, 2019 5:41 pm 
Reply with quote Top  
G'day everyone i got back from a week long 4wd trip and really my only down fall was not enough ground clearance, what would i have to do to run 750 16s on the sierra? i like the style of the lj rims but if they aren't wide enough what other steel rims could i use that are a similar style?
Cheers Jack.

 Profile  

Offline
User avatar

Joined: Fri Apr 23, 2010 12:00 am
Posts: 669
Location: Hobart

Post Posted: Mon Nov 04, 2019 8:16 pm 
Reply with quote Top  
Can't help you with your question but do you have any spare narrow 16 inch rims?

 Profile  

Offline
User avatar

Joined: Mon May 05, 2014 12:20 pm
Posts: 1100
Vehicle: Vitara 1994

Post Posted: Tue Nov 05, 2019 1:38 pm 
Reply with quote Top  
Jack jr wrote:
G'day everyone i got back from a week long 4wd trip and really my only down fall was not enough ground clearance, what would i have to do to run 750 16s on the sierra? i like the style of the lj rims but if they aren't wide enough what other steel rims could i use that are a similar style?
Cheers Jack.


There are plenty of options out there from factory Suzuki wheels to aftermarket options like sunraysia’s that arnt that expensive new


Sent from my iPhone using Tapatalk

 Profile  

Offline
User avatar

Joined: Fri Mar 30, 2007 12:00 am
Posts: 14329
Location: Here there everywhere
Vehicle: A manly awesome man jimny

Post Posted: Tue Nov 05, 2019 3:31 pm 
Reply with quote Top  
Just put 700 or 750r15 tyres on the Sierra rims. I have 750r15 tyres on Sierra rims fitted to my box trailer

_________________
JEEPJEEPJEEPJEEPJEEPJEEPJEEPJEEPJEEP

 Profile  

Offline
User avatar

Joined: Thu Feb 26, 2009 11:00 pm
Posts: 11418
Location: Melbourne

Post Posted: Tue Nov 05, 2019 5:45 pm 
Reply with quote Top  
Firstly, you're absolutely going to need to correct off road gearing if you fit 7.50's. I drove a 1.3 Sierra with stock gearing and 7.50's for a while, and it was very hard on the car because it was always traveling too quickly and i had to be hard on the clutch and throttle to drive it in steep country. It's unnecessarily abusive. (at the time, reduction gears didn't exist)

7.50's are hard to fit with NT axles. Again, my car was NT and i was running flipped and offset F150 rims, and with ~1" of body lift i had lots of scrubbing. With more conventional offset, the tyres will foul hard on the inner guards and shock mounts when the steering is turned and the car is flexed up.

Next you need to address your tyre choice. I like crossply tyres off road (a lot) but once you're up at 7.50, they tend to have very high load and ply ratings, as these days they're predominantly used as drive tyres in small trucks. 10ply + isn't uncommon. This makes the tyres poor at conforming to the terrain on a car as light as a sierra so you give up a lot of traction, especially on ground where small rocks etc are breaking through. 6.00X16's are very very soft in comparison.

Bear in mind the LJ/Sierra rims are a tube rim and if you run low pressure to try and make stiff tyres work you will experience tube pinching. I had this happen at 5 psi with 9/34 swampers on sierra 16" rims.

Your best bet for a "classic" looking 16" rim that will take a 7.50 is the F150 rim. It will need the centre bored to clear the Sierra hub and you'll want more offset to keep the tyres off the springs. Here they are on a WT sierra with 7.50X16's on them. These are Firestone SAT's, truly excellent off road and only 6 ply. In the early to mid 1990's (when I got them) they were THE off road tyre for landrovers in the UK.

Image

Here is Piggles a VERY long time ago with Sierra 16"s and 9/34's on it when it was still on 1.0 litre axles. It fell over a LOT (it still does, but now it falls over when I do something silly. It used to fall over when it shouldn't have) this was running a 2" body lift and 2" bumpstop spacing to clear the 34's, with 7.50's it would only need either/or, not both. The 9/34's were very pinched and crowned badly on these rims.

Image


Here are the same tyres on WT axles with the offset, beadlocked F150 rims.

Image

and the track width.

Image

That's a Calmini flare which is about 4" wide.

I was happy with the stability of the car with this setup.

Oh, you can buy alloy rims ex-japan styled to look like the LJ rim:

Image

Image

but really, once you're on a 7.50, spring clearance and steering lock are going to be a bit of a pain, and you'll really notice the lost stability.

I'd go to WT axles before I considered a tyre that tall.

_________________
hillbilly 2 wrote:
Gwagensteve is why auszookers will never be taken seriously

 Profile  

Offline
User avatar

Joined: Thu Feb 26, 2009 11:00 pm
Posts: 11418
Location: Melbourne

Post Posted: Tue Nov 05, 2019 5:48 pm 
Reply with quote Top  
Oh, I need the add the Black WT could get away with no body lift and no bumpstop spacing with those rims/tyres because it had previously had a massive guard chop, in a previous life it ran 35's.

It subsequently, many years later, ended up back on 35's at the same height it is in that photo.

_________________
hillbilly 2 wrote:
Gwagensteve is why auszookers will never be taken seriously

 Profile  

Offline
User avatar

Joined: Mon Jul 08, 2019 10:27 am
Posts: 131
Vehicle: Suzuki sierras

Post Posted: Tue Nov 05, 2019 7:18 pm 
Reply with quote Top  
G'day i should of mentioned that this is for my swb wt, i'll get some reduction gears. and i'll find a slightly wider set of 16 inch rims. thanks for all the information.
Cheers Jack.

 Profile  

Offline
User avatar

Joined: Thu Feb 26, 2009 11:00 pm
Posts: 11418
Location: Melbourne

Post Posted: Tue Nov 05, 2019 8:08 pm 
Reply with quote Top  
You can use GV rims, but these are a little wide for 7.50's. They're a helpful offset though.

_________________
hillbilly 2 wrote:
Gwagensteve is why auszookers will never be taken seriously

 Profile  

Offline

Joined: Thu Sep 02, 2010 6:20 am
Posts: 382
Location: Melbourne
Vehicle: '85 Sierra LWB, '99 GV 2.5L

Post Posted: Sun Nov 10, 2019 9:33 pm 
Reply with quote Top  
The modern 'equivalent' of 7.50 x 16 is 235/85R16 - although that works out to be 9 & 1/4" wide, but with similar overall height of around 32".
A 16 x 7" GV rim is perfect (the original GV tyre size is 235 wide, but 60% profile), but if a 7.50 (190mm wide) tyre is a pain to fit, then 235mm wide would be a bigger pain.
They bolt onto a N/T with a 235 tyre just inside the skinny plastic flares.
Rgs, Michael

 Profile  
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 19 posts ] 

Jump to:  


Who is online

Users browsing this forum: No registered users and 2 guests

You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum
Untitled Document


Untitled Document


Powered by phpBB © 2000, 2002, 2005, 2007 phpBB Group :: Style based on FI Subice by phpBBservice.nl :: All times are UTC + 10 hours