Hey all.
Got a question about the turbo boxes 1st & 2nd ratios and how they feel different to the NA gearbox's 1st & 2nd ratios.
What I want to know is which box has the closer ratio in 1st & 2nd? I would imagine that the turbo has closer ratios to keep the turbo spooled up and on boost getting off the mark.
Reason i'm asking is that fitting bigger tyres to the L will make the engine struggle off the line. If the turbo box has closer ratios this will make it slightly easier for the engine to do its work to get off the mark quicker (not that i'm going for a sports car performance, would like to be as close to standard performance as possible with larger tyres).
Clear as mud?
Cheers
Bennie
L series Turbo/NA box gear ratio question.
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discopotato03
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Hi Bennie , no its the other way around - the turbo gear ratios for both RX L series and RS Liberty (1st gen anyway) are the wider spaced ones .
The reason why many manufacturers do this is because believe it or not the turbo engine variants make more lower mid range torque than the naturally aspired ones do . Most smaller emission control NA engines don't make their peak torque until reasonably high in their typically usable rev range .
Normally turbo engines like to have a load to push against because it drives them into a supercharged (boosted) state a little earlier . Can go into the nitty gritty but most are not that interested - let me know .
Anyhow an easy way to place more load on an engine is to open up the gear spacing so that there's less reduction and a higher torque requirement or load placed on the engine after the up change .
The NA L series 1-2 are 3.545 - 2.111 , The RX and RS are 3.545 - 1.947 .
The way these gearboxes are designed sometimes forces you to change both pairs of gears if altering the ratios . So to change second means changing both sets of gears because their mainshaft gears are part of the shaft itself . First ratio is the same so no dramas there .
Third and fourth must also be changed as a pair because their idler gears are machined into a common piece of steel .
Fifth gear pair are the only ones isolated from any other .
From what I can tell all RX's and late MPFI L's use the wide turbo gear ratios and the taller low range gears . Earlier and possibly most carby L's use the closer ratio set and the shorter low range gears .
Possibly the close ratios 1-4 and the turbo 5th gears may be the most versatile way to go so long as you don't mind the wider gap between 4th and 5th .
If you went for short diff ratios you can still get an acceptable cruising 5th gear if you can find the taller again EJ single range turbo 5th gear pair .
5th options , Close ratio one 0.87 , turbo L 0.78 , later turbo EJ 0.738 .
Just to irritate everyone .
For a part time box if you want the L turbo 5th gears they need to come from an RX or late MPFI L PT box because the L and EJ AWD ones are different on the countershaft .
If you have an L AWD box they have the same turbo ratios as an RX L .
If you want the close spaced gearset for an AWD box (L or EJ) the easiest way is to rob a 1st gen dual range Liberty box that has the 3.9 diff ratio .
Cheers A .
The reason why many manufacturers do this is because believe it or not the turbo engine variants make more lower mid range torque than the naturally aspired ones do . Most smaller emission control NA engines don't make their peak torque until reasonably high in their typically usable rev range .
Normally turbo engines like to have a load to push against because it drives them into a supercharged (boosted) state a little earlier . Can go into the nitty gritty but most are not that interested - let me know .
Anyhow an easy way to place more load on an engine is to open up the gear spacing so that there's less reduction and a higher torque requirement or load placed on the engine after the up change .
The NA L series 1-2 are 3.545 - 2.111 , The RX and RS are 3.545 - 1.947 .
The way these gearboxes are designed sometimes forces you to change both pairs of gears if altering the ratios . So to change second means changing both sets of gears because their mainshaft gears are part of the shaft itself . First ratio is the same so no dramas there .
Third and fourth must also be changed as a pair because their idler gears are machined into a common piece of steel .
Fifth gear pair are the only ones isolated from any other .
From what I can tell all RX's and late MPFI L's use the wide turbo gear ratios and the taller low range gears . Earlier and possibly most carby L's use the closer ratio set and the shorter low range gears .
Possibly the close ratios 1-4 and the turbo 5th gears may be the most versatile way to go so long as you don't mind the wider gap between 4th and 5th .
If you went for short diff ratios you can still get an acceptable cruising 5th gear if you can find the taller again EJ single range turbo 5th gear pair .
5th options , Close ratio one 0.87 , turbo L 0.78 , later turbo EJ 0.738 .
Just to irritate everyone .
For a part time box if you want the L turbo 5th gears they need to come from an RX or late MPFI L PT box because the L and EJ AWD ones are different on the countershaft .
If you have an L AWD box they have the same turbo ratios as an RX L .
If you want the close spaced gearset for an AWD box (L or EJ) the easiest way is to rob a 1st gen dual range Liberty box that has the 3.9 diff ratio .
Cheers A .
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El_Freddo
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Thanks A.
The loading of the engine to help spool up the turbo quicker makes sense. More load down low = more fuel to burn between spark detonation to the turbo exhaust turbine...
My thinking was that first and second were shorter than the NA to help get the engine on boost quicker - this would also help for general cruising when you don't want to be using the turbo too much (going for the economy run...).
Not to worry. Its interesting to note that the 1st gear ratio is the same between the turbo and NA boxes.
I'm guessing you can't get the L AWD gearbox and use a set of NA gearsets in there (or the EJ gearset from a 3.9 as you were suggesting) without loosing the locking centre diff...
I'm aiming to end up with my rube build as an offroader with the lockable centre diff, but also don't want it to be a slug off the mark and around town... The changing of the pinion to fit a 4.11 diff sounds the go - I'd probabily whack it all into the EJ casing and run either the EJ20 or EJ22 (the 22 are easy to get, it would cost 200 for the engine, 60 for the loom and if you can slip the computer past your set. Exhaust to cat will be about 30 from memory - pick a part prices). $400 or there abouts for the change of pinion sounds pretty good for whats involved.
I'm asking these questions as the ball may have started rolling, i'd like to know what i can do now rather than later, that way i can make plans etc.
I'd also like to get my speedo accurate after adding 27's to the ground, dunno if this can be done by matching gearsets, diff ratio to the 27's...
All plans at the moment, but if i can do what i want i'd be very happy with my L...
Cheers
Bennie
The loading of the engine to help spool up the turbo quicker makes sense. More load down low = more fuel to burn between spark detonation to the turbo exhaust turbine...
My thinking was that first and second were shorter than the NA to help get the engine on boost quicker - this would also help for general cruising when you don't want to be using the turbo too much (going for the economy run...).
Not to worry. Its interesting to note that the 1st gear ratio is the same between the turbo and NA boxes.
I'm guessing you can't get the L AWD gearbox and use a set of NA gearsets in there (or the EJ gearset from a 3.9 as you were suggesting) without loosing the locking centre diff...
I'm aiming to end up with my rube build as an offroader with the lockable centre diff, but also don't want it to be a slug off the mark and around town... The changing of the pinion to fit a 4.11 diff sounds the go - I'd probabily whack it all into the EJ casing and run either the EJ20 or EJ22 (the 22 are easy to get, it would cost 200 for the engine, 60 for the loom and if you can slip the computer past your set. Exhaust to cat will be about 30 from memory - pick a part prices). $400 or there abouts for the change of pinion sounds pretty good for whats involved.
I'm asking these questions as the ball may have started rolling, i'd like to know what i can do now rather than later, that way i can make plans etc.
I'd also like to get my speedo accurate after adding 27's to the ground, dunno if this can be done by matching gearsets, diff ratio to the 27's...
All plans at the moment, but if i can do what i want i'd be very happy with my L...
Cheers
Bennie
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discopotato03
- Senior Member
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- Location: Sydney
Hi Benny , once you have the L type locking box or its extension and internals you can go virtually anywhere with it (mechanically speaking) . You must have the long front diff pinion to make it work .
All these are internally is an AWD box with the center diff turned around and the transfer drive gear on the front of the center diffs steel casing . Subaru obviously wanted to keep the L locking box dimensionally interchangeable with the part time one so that it was an easy bolt in option on the production line ie same tailshaft /mounts/cables/control rods .
Because the shafts ahead of this locking diff are the same dimensionally (low range gears aside) , you could pull its extension and internals out and replace them with the later viscous diff and longer EJ extension housing bits .
So to answer your question , yes you can fit EJ AWD ratios in the L type AWD gearbox .
Its the low range feature that adds complication because you need to find the two piece mainshaft (back half anyway) with its integral 1st and 2nd gears .
Also the L series cars have that overcomplicated LR selector rod that runs down the drivers side of the box and has its detent mechanism in the top of the extension . Silly me didn't know that Liberty's use a cable and that the detent is inside the case on the selector fork so I have the rod system as per normal L .
To get the speedo right I think you need to alter the speedo drive gear in the box itself , unfortunately Subaru don't make the whole speedo drive housing removable like Nissan does so it has to be done with the box out and split .
Someone here has probably done this so ask around .
With the front diff pinion , half the reason to change the gear on it is because its shaft is unique , longest of all the Sube front pinions because it runs right through the middle of the center diff and supports the back of it in a bearing in the bottom of the extension's end plate . As far as being a differential is concerned the L and the EJ's do it differently , from what I can tell splines inside the back of diff lock coupling sleeve transmit drive from the gearboxes hollow countershaft to another hollow shaft behind it that forms the differentials cross pins . So the cross pins drive the small bevel gears which have the side gears either side of them and they drive the front pinion or the center diffs hemisphere which has the transfer drive gear on the front of it - takes drive up to the output shaft and rear diff .
What the locks coupling sleeve does when it moves rearward is lock the hollow countershaft in front to the center diffs hemisphere so it all revolves at the same speed - direct drive to the front pinion and transfer drive gear .
The EJ system is different in that the splines on the hollow countershaft that drove the lock sleeve in the earlier system drive the viscous type diffs outer case or hemisphere which drives the diffs cross pins . The front half of the viscous hub which is effectively the front half of the center diff has an internal splined sleeve which drives splines on the shorter than L AWD type pinion and thus the front wheels . The rear side gear of the center diff is splined and drives a separate rear mounted transfer shaft / gear .
All different because the L system drives the front diff from the back of the centre diff and the back from the front of the center diff .
The EJ system drives the front from the front and the back from the back .
I'm sorry if this is as clear as mud because I have the manuals for both systems in front of me and I'm probably not too good at turning words into pictures .
Honestly if on road performance handling is irrelevant the part time box is so much cheaper and easier for an EA82 in an L series , cost wise (IMO) it all reverses with EJ's in L's . The cost of re engineering an L would take considerable time to recoup in petrol dollars in a larger more modern Liberty which has 90% of the desirable bits std - and if you shop around they can be had cheaply for what you get .
The only reason I went for an L RX sedan is because its small and light and weighs 270 kg less than a 1st gen RS Turbo . If onroad performance is your meat then weight and agility is critical to the overall result .
If I was driving Marge Bart and Lisa around they'd hate me less if it was in a Liberty rather than an L series , I do a fair few miles and 90% of them are by myself . Also I got my car cheaply ($2000) which was pure luck and a round trip Syd Melb at the time .
All these are internally is an AWD box with the center diff turned around and the transfer drive gear on the front of the center diffs steel casing . Subaru obviously wanted to keep the L locking box dimensionally interchangeable with the part time one so that it was an easy bolt in option on the production line ie same tailshaft /mounts/cables/control rods .
Because the shafts ahead of this locking diff are the same dimensionally (low range gears aside) , you could pull its extension and internals out and replace them with the later viscous diff and longer EJ extension housing bits .
So to answer your question , yes you can fit EJ AWD ratios in the L type AWD gearbox .
Its the low range feature that adds complication because you need to find the two piece mainshaft (back half anyway) with its integral 1st and 2nd gears .
Also the L series cars have that overcomplicated LR selector rod that runs down the drivers side of the box and has its detent mechanism in the top of the extension . Silly me didn't know that Liberty's use a cable and that the detent is inside the case on the selector fork so I have the rod system as per normal L .
To get the speedo right I think you need to alter the speedo drive gear in the box itself , unfortunately Subaru don't make the whole speedo drive housing removable like Nissan does so it has to be done with the box out and split .
Someone here has probably done this so ask around .
With the front diff pinion , half the reason to change the gear on it is because its shaft is unique , longest of all the Sube front pinions because it runs right through the middle of the center diff and supports the back of it in a bearing in the bottom of the extension's end plate . As far as being a differential is concerned the L and the EJ's do it differently , from what I can tell splines inside the back of diff lock coupling sleeve transmit drive from the gearboxes hollow countershaft to another hollow shaft behind it that forms the differentials cross pins . So the cross pins drive the small bevel gears which have the side gears either side of them and they drive the front pinion or the center diffs hemisphere which has the transfer drive gear on the front of it - takes drive up to the output shaft and rear diff .
What the locks coupling sleeve does when it moves rearward is lock the hollow countershaft in front to the center diffs hemisphere so it all revolves at the same speed - direct drive to the front pinion and transfer drive gear .
The EJ system is different in that the splines on the hollow countershaft that drove the lock sleeve in the earlier system drive the viscous type diffs outer case or hemisphere which drives the diffs cross pins . The front half of the viscous hub which is effectively the front half of the center diff has an internal splined sleeve which drives splines on the shorter than L AWD type pinion and thus the front wheels . The rear side gear of the center diff is splined and drives a separate rear mounted transfer shaft / gear .
All different because the L system drives the front diff from the back of the centre diff and the back from the front of the center diff .
The EJ system drives the front from the front and the back from the back .
I'm sorry if this is as clear as mud because I have the manuals for both systems in front of me and I'm probably not too good at turning words into pictures .
Honestly if on road performance handling is irrelevant the part time box is so much cheaper and easier for an EA82 in an L series , cost wise (IMO) it all reverses with EJ's in L's . The cost of re engineering an L would take considerable time to recoup in petrol dollars in a larger more modern Liberty which has 90% of the desirable bits std - and if you shop around they can be had cheaply for what you get .
The only reason I went for an L RX sedan is because its small and light and weighs 270 kg less than a 1st gen RS Turbo . If onroad performance is your meat then weight and agility is critical to the overall result .
If I was driving Marge Bart and Lisa around they'd hate me less if it was in a Liberty rather than an L series , I do a fair few miles and 90% of them are by myself . Also I got my car cheaply ($2000) which was pure luck and a round trip Syd Melb at the time .
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El_Freddo
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Thanks for the info Adrian,
When you say that i can run the EJ ratios in the EA AWD box are you meaning to say that I can run what is essentially and EJ box in an EA casing? I know this all fits in already.
If I wasn't clear enough what I meant was - can I run N/A EJ (or EA for that matter) ratios with the locking centre diff?
It seems to me that running an N/A motor (EA at this stage) it is not a good point to be running a turbo AWD box with larger tyres - simply because the engine would be better off using the NA ratios against the larger tyres...
Sound right?
Bennie
When you say that i can run the EJ ratios in the EA AWD box are you meaning to say that I can run what is essentially and EJ box in an EA casing? I know this all fits in already.
If I wasn't clear enough what I meant was - can I run N/A EJ (or EA for that matter) ratios with the locking centre diff?
It seems to me that running an N/A motor (EA at this stage) it is not a good point to be running a turbo AWD box with larger tyres - simply because the engine would be better off using the NA ratios against the larger tyres...
Sound right?
Bennie
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discopotato03
- Senior Member
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- Joined: Sun Mar 18, 2007 9:29 am
- Location: Sydney
Yes . Effectively the larger diameter wheels do the same thing as a taller diff ratio so closer spaced gear ratios would make life easier for the carby 82 .
If you car has a carby part time dual range box std and 3.7 diffs that would feel the same as a L AWD one with the closer ratios . And off the road it IS the same as a AWD box when locked .
Cheers A .
If you car has a carby part time dual range box std and 3.7 diffs that would feel the same as a L AWD one with the closer ratios . And off the road it IS the same as a AWD box when locked .
Cheers A .
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El_Freddo
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Taller diff ratio - you mean if i was to go from 3.9 ratio to the "taller" 3.7 ratio sort of situation?discopotato03 wrote:Yes . Effectively the larger diameter wheels do the same thing as a taller diff ratio so closer spaced gear ratios would make life easier for the carby 82 .
Or do you mean to go from the 3.X to the 4.11 as the taller ratio? Just a little confused with terminology here.
I'll also be looking into an EJ conversion later, no turbo...
Got that, I would like the AWD for better on road handling (plus just want the AWD lockable feature - bit of a stand out feature).discopotato03 wrote:If you car has a carby part time dual range box std and 3.7 diffs that would feel the same as a L AWD one with the closer ratios . And off the road it IS the same as a AWD box when locked .
Thanks for all your info so far Adrian, its been greatly appreciated. Just can't wait to get my hands on one!
Cheers
Bennie