Hello all
I am in need of getting a new 9" diff made.
What would be the best to get for a street car as in strongest/lightest?
My plans so far are 60mm shorter either side, bigger bearings and true track.
Does anyone have any thoughts on the Strange Ultra Case or the Strange 12 bolt drop in centre?
Has anyone had any dealings with Pro9?
9" Diff. What is good/not good
Started by
_the gts_
, Apr 29 2012 09:02 AM
26 replies to this topic
#2
wot179
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Posted 29 April 2012 - 09:49 AM
Ask yourself how often you think you might need a drop in center before you go the 9 inch route.
Make the right decision the first time by asking what people use and what they use it for.
Tyre height should be compared in this research as well.
Every combo has been tried a million times,and it wont be that hard to find the right ratio for your intended use.
It is good to see you are at least considering a 12 bolt option.
I think you should take it a step further and stay away from the sheep mentality of 9 inch being the only option,and go with the regular Strange 12 bolt.
They are more than strong enough for nearly any 5 litre application in a small, light car like a Torana.
90% of 9 inch conversions are a result of a sheep mentality where the public assume they are the only option.
Bah humbug.
They might be the best option for a foulcan,My opinion is to keep it GM.
It will cost you the same money if you are going aftermarket everything anyway.
Good luck with your conversion.
Make the right decision the first time by asking what people use and what they use it for.
Tyre height should be compared in this research as well.
Every combo has been tried a million times,and it wont be that hard to find the right ratio for your intended use.
It is good to see you are at least considering a 12 bolt option.
I think you should take it a step further and stay away from the sheep mentality of 9 inch being the only option,and go with the regular Strange 12 bolt.
They are more than strong enough for nearly any 5 litre application in a small, light car like a Torana.
90% of 9 inch conversions are a result of a sheep mentality where the public assume they are the only option.
Bah humbug.
They might be the best option for a foulcan,My opinion is to keep it GM.
It will cost you the same money if you are going aftermarket everything anyway.
Good luck with your conversion.
#3
_oldjohnno_
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Posted 29 April 2012 - 10:02 AM
Couldn't agree more Wot. The 9" certainly has it's place, and sometimes it's the only thing that will survive but I think of it as being a last resort. The gear design has a lot of drag and it's not uncommon to lose a tenth or two other diffs, or even more with a moderately powered car. The removeable centre is nice but by the time you remove and refit the axles and the centre is it really that much quicker than just changing the whole unit over?
Unless I absolutely had to run a 9" I'd much prefer a something like a BW or 12 bolt.
Unless I absolutely had to run a 9" I'd much prefer a something like a BW or 12 bolt.
#4
BIG KEV
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Posted 29 April 2012 - 10:48 AM
hi guys
i have been thinking about this very same thing .like many other car nuts i to was ready for a 9'' but then a mate recondmended a chev 12 bolt here comes the problem from the home work i have done yes you can still buy new parts from the states yes the 12 bolt can handle the power the problem is cutting and rewelding the ears on the cast case and as for price the 12 bolt is slightly more $$$ having said that this is why i am still thinking 9'' more bang for your buck ..... but i am still doing the home work on the 12 bolt to have a all gm car
i have been thinking about this very same thing .like many other car nuts i to was ready for a 9'' but then a mate recondmended a chev 12 bolt here comes the problem from the home work i have done yes you can still buy new parts from the states yes the 12 bolt can handle the power the problem is cutting and rewelding the ears on the cast case and as for price the 12 bolt is slightly more $$$ having said that this is why i am still thinking 9'' more bang for your buck ..... but i am still doing the home work on the 12 bolt to have a all gm car
#5
_moot_
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Posted 29 April 2012 - 10:50 AM
ive done my diff 3 times. i would do it this way:
aftermarket new housing (need this for 35 spline) due to bigger bearing size
use 35 spline axles.mine are 31's are will be on there limit.
detroit centre.
i wouldnt bother with fancy parts to much,and the weight difference is bugger all compared to a bw diff. (youir car will need a 9")
check wheel backspacing for the brakes you wanna use.i cant use discs now as the caliper would be used as a bump stop.its hard up against the chassis rail.
my diff also has billet top mounts to hold the bush in much nicer than a folded mount.
the bottom mounts are moved in 100+mm and i have bent chromoly lower arms with helm joints to clear the tyre.the mounts are 6mm plate
my diff has the big brace across the back with coilover mounts and panard rod.
a proper drain plug is nice
all things to think about
aftermarket new housing (need this for 35 spline) due to bigger bearing size
use 35 spline axles.mine are 31's are will be on there limit.
detroit centre.
i wouldnt bother with fancy parts to much,and the weight difference is bugger all compared to a bw diff. (youir car will need a 9")
check wheel backspacing for the brakes you wanna use.i cant use discs now as the caliper would be used as a bump stop.its hard up against the chassis rail.
my diff also has billet top mounts to hold the bush in much nicer than a folded mount.
the bottom mounts are moved in 100+mm and i have bent chromoly lower arms with helm joints to clear the tyre.the mounts are 6mm plate
my diff has the big brace across the back with coilover mounts and panard rod.
a proper drain plug is nice
all things to think about
#6
wot179
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Posted 29 April 2012 - 11:30 AM
Most Chev 12 bolts have no ears to cut off. Certainly a strange aftermarket housing would be unusual to have them.hi guys
i have been thinking about this very same thing .like many other car nuts i to was ready for a 9'' but then a mate recondmended a chev 12 bolt here comes the problem from the home work i have done yes you can still buy new parts from the states yes the 12 bolt can handle the power the problem is cutting and rewelding the ears on the cast case and as for price the 12 bolt is slightly more $$$ having said that this is why i am still thinking 9'' more bang for your buck ..... but i am still doing the home work on the 12 bolt to have a all gm car
Fabricating and welding on top control arm mounts to a cast steel housing should provide no challenge for a skilled fabricator.
#7
_LS1 Hatch_
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Posted 29 April 2012 - 11:31 AM
Most Chev 12 bolts have no ears to cut off.
Depends...if the housing was out of a Chevelle it will, if it was a Camaro one it would not. Just depends on what you got a housing out of? (assuming you are talking about starting out with a second hand one)
#8
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Posted 29 April 2012 - 11:37 AM
hi jeff
can you buy a new all steel 12 bolt or do i need to find a second hand chevelle
can you buy a new all steel 12 bolt or do i need to find a second hand chevelle
#9
_LS1 Hatch_
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Posted 29 April 2012 - 11:42 AM
Yep, you can buy them brand new now...would have to check into it though for sure for costs and things.
(I have a 9" in my car by the way, ha ha...)
(I have a 9" in my car by the way, ha ha...)
#10
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Posted 29 April 2012 - 12:06 PM
when you say yep you can buy new is that all steel and would that be a blank diff without brakets etc and not to length i would be interested in cost to get one over here and set up over a locally built 9''
#11
_LS1 Hatch_
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Posted 29 April 2012 - 12:09 PM
Maybe shoot Moser an email for a price on a bare housing ?
http://www.moserengi...nfigurator.html
Shipping it to Melbourne is easy enough, just not sure on costs for the diff or anything since I've never shopped for one. Might be other companies doing them too ? (maybe check with Strange as well for instance ?)
http://www.moserengi...nfigurator.html
Shipping it to Melbourne is easy enough, just not sure on costs for the diff or anything since I've never shopped for one. Might be other companies doing them too ? (maybe check with Strange as well for instance ?)
#12
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Posted 29 April 2012 - 01:36 PM
thanks for the link jeff ,i will make some phone calls during the week and i will let you guys know $$$ wise which way 12 bolt or 9'' eg:if it cost more to import a 12 bolt over a locally built 9''
#13
_the gts_
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Posted 29 April 2012 - 03:36 PM
Thanks for the info.
I already have a 9" with 28 spline (i think) plus I would like one approx 58mm shorter each side. I already have minitubs & coil over shocks so I am hoping 58mm will be ok?
My engine is somewhere between 5-600hp chev and the tyre size is 646mm OD. I was thinking along the lines of 35 spline axles & the 12bolt centre. Apparently the 12 bolt centre is a little bit lighter and also slightly more efficient but will it handle 500+hp?
I would prefer to stay with the 9" as everything else has already been modified and built around it but would just like to know where it can be improved.
Cheers
I already have a 9" with 28 spline (i think) plus I would like one approx 58mm shorter each side. I already have minitubs & coil over shocks so I am hoping 58mm will be ok?
My engine is somewhere between 5-600hp chev and the tyre size is 646mm OD. I was thinking along the lines of 35 spline axles & the 12bolt centre. Apparently the 12 bolt centre is a little bit lighter and also slightly more efficient but will it handle 500+hp?
I would prefer to stay with the 9" as everything else has already been modified and built around it but would just like to know where it can be improved.
Cheers
#14
ls2lxhatch
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Posted 29 April 2012 - 10:39 PM
I would get new bracketry made for the trailing arm mounts. Possibly the McDonald Bros brackets without the shock mounts and spring pads.
It would be worth considering using this style of upper control arm mount. Usually you can get some height adjustament and makes it easier to change upper bushes.
The gears will wear quicker in a 9" alloy case than they will in a iron case due to the alloy case flexing.
It would be worth considering using this style of upper control arm mount. Usually you can get some height adjustament and makes it easier to change upper bushes.
The gears will wear quicker in a 9" alloy case than they will in a iron case due to the alloy case flexing.
Edited by ls2lxhatch, 29 April 2012 - 10:42 PM.
#15
_77hatch_
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Posted 30 April 2012 - 11:21 PM
I Can understand the "GM" deal BUT just like you can buy a 12 bolt after market you can buy a 9" aftermarket , you can build a complete 9" from axle to axle without one genuine ford part !!!!!! if im gonna waste money on a conversion (like i already have) it won't be a b/w, they aren't that much lighter & and they aren't stronger !!!!!!!!!!!!!! im not a ford man but i build diffs & gearboxes for a living ! ...........cheap ...tough ..... 9" .........bang for buck!!!! im sorry but holden had a history of putting crap diffs in their cars !!!!!!! , just like ford made cars that only go in straight lines!!!!!
#16
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Posted 30 April 2012 - 11:53 PM
I'd have to agree, bang for buck 9inch, I use 1, my pinion yoke is the only genuine ford part in it, I've been use a strange alloy carrier for years, it it is a lot lighter than a bw.
Choice and availability of parts just nothing compares.
Iv seen them all break 12 bolt, bw and 9 inch, the guy behind the 5th wheel usually the cause.
If your going to add more power later, 9i ch is the way.
Iv had my diff changed so the upper arms have bushes both ends, and have height adjustment on housing, can be good tuning aid.
Choice and availability of parts just nothing compares.
Iv seen them all break 12 bolt, bw and 9 inch, the guy behind the 5th wheel usually the cause.
If your going to add more power later, 9i ch is the way.
Iv had my diff changed so the upper arms have bushes both ends, and have height adjustment on housing, can be good tuning aid.
Edited by ozyozyozy, 30 April 2012 - 11:55 PM.
#17
A9X
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Posted 01 May 2012 - 11:08 AM
i've seen you drive, you need a 9 inch !
#18
_the gts_
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Posted 01 May 2012 - 05:39 PM
Does anyone know if it is worth having adjustable holes on the trailing arm mounts so you can adjust anti squat characteristics?
#19
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Posted 01 May 2012 - 09:35 PM
i have mucked around with the anti squat.
from factory the setup isent good for racing under power, rear end dosent sqaut, it lifts.
if you move the top arm away from the diff, this gives more weight transfer to front wheels, more mid corner steering.
if you lower the arm gives more rear grip.
it helps as a tunig aid.
those upper arms need to be the length of lowers to make the rear end work propperly, i vote equal length arm 3 link or 4 link, this is what the big boys are doing.
from factory the setup isent good for racing under power, rear end dosent sqaut, it lifts.
if you move the top arm away from the diff, this gives more weight transfer to front wheels, more mid corner steering.
if you lower the arm gives more rear grip.
it helps as a tunig aid.
those upper arms need to be the length of lowers to make the rear end work propperly, i vote equal length arm 3 link or 4 link, this is what the big boys are doing.
#20
wot179
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Posted 01 May 2012 - 09:58 PM
BAAA-AAA-AAA
#21
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Posted 01 May 2012 - 10:50 PM
I use the Strange alloy lightweight case with no drama's at all. It weighs as much as a BW, cost a bit more and has handled the manual big block so far.
#22
_the gts_
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Posted 02 May 2012 - 02:53 PM
So Ozzy
area you suggesting that If i was to keep the standard 4 link and wanted more rear traction I should get adjustable lower trailing arm mounts, similar to the complete housing that LS2hatch posted above?
SS427 do you know the part number of the case that you are using?
area you suggesting that If i was to keep the standard 4 link and wanted more rear traction I should get adjustable lower trailing arm mounts, similar to the complete housing that LS2hatch posted above?
SS427 do you know the part number of the case that you are using?
#23
ls2lxhatch
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Posted 02 May 2012 - 03:51 PM
You can get adjustable lower and upper mounts fitted to the diff. I only have adjustable upper. The top two holes are usuable with standard size bushed arms, the top hole is standard height.
Edited by ls2lxhatch, 02 May 2012 - 03:51 PM.
#24
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Posted 03 May 2012 - 12:46 AM
well guys i just rang moser diffs in the states and bad luck 12 bolt diffs are being remade and they have a cast housing i was hoping for a al steel unit looks like i wii have to find a good place to buld me a 9''
#25
unclefestal34s
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Posted 03 May 2012 - 12:03 PM
hi big kev...just letting you no i have a complete 12 bolt with 3.55 ratio drum to drum ideal for a conversion..let me no if your still interested
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