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Senior Member
Subaru 5 speed front LSD's
Hey all. Looking for a little help - I appreciate that the Cusco, Quaife and Kaaz front transmission LSD's are generally designed and built with the intention that it is still being used in an AWD front axle setup.. However what I'm hoping for and looking for desperately is a 2 way LSD suitable for the 818 rear axle. Surely all of us installing LSD's would prefer a 2 way? I recently spoke with someone associated with Cusco Japan - they will specifically build us a 2 way LSD provided we order 50x of them. We could almost consider a group buy?
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Member
G'day Junty,
Happy new year!
Ironically, I was just speaking to a mate the other day about an LSD for the 818, as I see a lot of guys in the US are fitting them, either during their builds or pretty soon after getting them going...
In response to your post, I'd be interested in one, and I know another builder in Perth,WA who would most likely be interested in one as well.
I have discovered that my transmission may have been sourced from a 08-09 UDM Outback turbo which was not sold in Aus, and possibly has a final ratio of 4.11 or 4.44. TY758VWABA is the tranny code. If this is true, I'll be exploring options for retrofitting a lower geared diff, such as a 3.90 or so. On the road I find first gear is almost redundant, given the light weight 818 compared to the WRX/Outback...
Obviously, this is dependant on their pricing 'structure'!
Cheers.
Last edited by Hendow; 01-10-2015 at 10:28 PM.
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Senior Member
I have a Cusco in the orange 818. I am pulling it out. I will not be putting one in the new 818 either. Tony at F5R said they are not running LSD anymore either. Not sure if it is weight, placement or axle geometry but it nearly binds on slow turns. Jim rode in the orange 818 and confirmed the LSD was binding and advised not to drive it till removed as he said if it locks up on the highway, it won't be pretty.
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Moonlight Performance
If it locks up, it should result in both the left and right tires turning at the same speed. On a slow sharp turn, like turning sharply into a parking spot, LSDs are known for causing a slight problem there but at highway speeds going straight?
If this is really a safety issue, we should all know about it now before too many people get theirs on the road with LSDs in place. I'm just confused as to why it would be an issue in the 818 specifically.
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Senior Member
Originally Posted by
Hindsight
If it locks up, it should result in both the left and right tires turning at the same speed. On a slow sharp turn, like turning sharply into a parking spot, LSDs are known for causing a slight problem there but at highway speeds going straight?
If this is really a safety issue, we should all know about it now before too many people get theirs on the road with LSDs in place. I'm just confused as to why it would be an issue in the 818 specifically.
It is a safety issue in my particular case. Does not mean it will be in others. When you say slight problem, this Cusco 1.5 will nearly stop the car at any speed under 5mph. A slight hesitation in a 3400lbs seem to be a bind in an 1800 lbs car. Went to a car show last week in an underground parking garage, it was aweful...the hard cluncks on every turn...felt like it was grabing every tooth. Maybe this unit is faulty, maybe it is just not the right one for this 818. What I do know, the transmission is out and an open is being installed. If anyone wants a great deal on a Cusco with under 1000 miles let me know.
Last edited by Kalstar; 01-11-2015 at 11:02 AM.
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Moonlight Performance
Interesting.... I guess we will just have to wait until we see what others experience with different brands. Mine will be a while yet but I think some others are getting close. I am pretty sure there are a few already on the road though.... Wayne??
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Senior Member
I am no expert at all -- but it seems to me that there was a discussion about the different types of LSD quite a while back (over a year ago), debating the merits of plate-type LSD's (like the Cusco) as opposed to gear driven torque-biasing types like the Quaife or OBX. The consensus was that the plate-type LSD's were better suited to on-track use while the gear driven ones were better for street use. Partly because the plate-types units were supposedly more effective at speed, and partly because the gear-type units are maintainance free. Could this issue with low-speed lockup also be different from one type to the other?
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PLATNUM Supporting Member
IMO the Cusco unit should have been in a track car. I had no experience with Subaru LSD's so I took advice from my transmission rebuilder. While the Cusco is basically transparent above 30MPH it is noisy at slow speed turns. It does provide excellent lockup under power in turns as well as straight ahead. More of a road race style unit IMO. I would have left the open diff in the car if this was explained to me up front. Unfortunately Kalstar is stuck with the problem. I personally could live with it and doubt it would ever lock up going down the highway. I do not fault anyone who does not want to chance it though. Gear unit may be best way to go or at least a .5 unit IMO.
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Senior Member
It is going to snow here over the next few days. I will stick a gopro in the engine bay and see if I can record the sounds in a few days. When Wallace delivered the car you could feel the LSD but it was not overly intrusive, now once broken in, it will nearly stop the car coming out of a parking spot. Either way, an open is the way I am going with the new car. I will post the recording as soon as I can. Btw, not knocking Wallace in anyway, he is a great builder, I would recommend him to anyone.
Last edited by Kalstar; 01-12-2015 at 09:14 AM.
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Senior Member
Can anyone out there with first-hand experience in a completed 818 with a Quaife-style LSD share their observations regarding low-speed lockup?
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Originally Posted by
Silvertop
Can anyone out there with first-hand experience in a completed 818 with a Quaife-style LSD share their observations regarding low-speed lockup?
If you are using a torque biasing differential like a Quaife, or Modena, it will never lock up. They are all gear driven.
The clutch type differentials will lock up as wheel speed, and a popping noise when turning is actually normal.
One thing to keep in mind is that if you are running a Cusco or clutch type differential, you need to run at least a quart or two of fluid formulated for a limited slip additive, you may see more popping noise from the clutches in the differential.
When we ran the Cusco differential in our Rally Car, we would run a couple of quarts of Redline Shockproof gear oil with our normal transmission fluid, and that seemed to work best.
Also, in terms of the diff and the weight of the car. It is possible that the lock-up is more than needed as the diff comes from Cusco, but remember that the Cusco differentials can be adjusted to change your pre-load (by changing the number of pre-load springs), and lock-up (by alternating clutch packs). The differentials come set at a maximum from Cusco, so you may want to try reducing the pre-load or the lock-up to get it dialed in properly.
Just in terms of set-up, for anything that is not a 100% race-car, a 1.5 way clutch diff should be sufficient, and even if you are running slicks, the 1.5 way will most likely be the way to go.
If you are in a street only car, the TBD will have better daily manners, and will be sufficient for stock to moderate power levels. If you are making a good deal of power, you will most likely be able to break the rear wheel lose, and once that happens, the TBD will behave as an open differential, and that is the point where you would want a clutch type differential.
I hope that helps, and if requested, I can go into more detail about diff set-up, but I do not have time to do so now.
www.flatironstuning.com
303.402.5142
Your source for any Subaru parts that you may need to build your 818 from engine parts to gear sets, etc. We have what you need.
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Moonlight Performance
Thanks for the info!
Regarding this though:
Originally Posted by
FlatironsTuning
If you are making a good deal of power, you will most likely be able to break the rear wheel lose, and once that happens, the TBD will behave as an open differential, and that is the point where you would want a clutch type differential.
Are you sure that's accurate exactly as written? My understanding is that when one of the rear wheels begins to spin, the TBD will transfer torque to the wheel that is sticking.... that is the whole point of the design and how the TBD even knows to transfer the power (one wheel beginning to move faster than the other). However, my understanding is that if one of the two rear wheels becomes airborne completely and has no contact with the road, it is then that the TBD will become an open diff.
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Originally Posted by
Hindsight
Thanks for the info!
Regarding this though:
Are you sure that's accurate exactly as written? My understanding is that when one of the rear wheels begins to spin, the TBD will transfer torque to the wheel that is sticking.... that is the whole point of the design and how the TBD even knows to transfer the power (one wheel beginning to move faster than the other). However, my understanding is that if one of the two rear wheels becomes airborne completely and has no contact with the road, it is then that the TBD will become an open diff.
Yes. We ran a TBD in our rally car for a bit, and then switched to the Cusco diff. There is a large difference in that scenario between the two, and the TBD definitely behaves more like an open diff compared to the locking diff.
If you drive one on ice as well, you will see that the TBD behaves like an open diff in low traction situations. Or for that matter, if you make enough power to brake a wheel lose, then the TBD will behave mostly like an open differential.
The difference between a TBD and open diff is that the open diff is only driving one wheel unless traction is exactly 50 - 50. The TBD is driving both wheels, though with a torque split, until one wheel has minimal to no resistance, and at that time, that low resistance wheel gets all of the drive force.
The Locking diff, once engaged because of difference in wheel spin (which you can adjust somewhat) will split power 50 - 50 between the two wheels until it un-locks.
Hopefully that helps.
www.flatironstuning.com
303.402.5142
Your source for any Subaru parts that you may need to build your 818 from engine parts to gear sets, etc. We have what you need.
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Senior Member
Originally Posted by
FlatironsTuning
The difference between a TBD and open diff is that the open diff is only driving one wheel unless traction is exactly 50 - 50.
Not really... By design, an open diff always applies the same torque to each wheel. So the wheel with greater traction is limited by the amount that can be delivered to the side with less traction. Even when one wheel is slipping, the other gets the same amount of torque. The term 'one wheel drive' is funny, but a bit of a misnomer by how an open diff behaves when one side has very little traction, spinning that side uselessly.
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Senior Member
But why is it then when " off roading" and one wheel is in the air, the other wheel has no traction?
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Senior Member
It all comes from the attribute that each wheel gets equal torque. If one wheel is in the air, it has no traction, and therefore can deliver no torque. The wheel on the ground has traction, but it gets the same torque as the wheel in the air... zero. Therefore, all motion goes to the wheel in the air.
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Both sides get the same torque, but one side uses that torque to create angular momentum. In doing so, it allows the crank to accelerate quickly enough so that the limiting factor is the inertia of the engine. At that point, very little of the energy produced goes to the wheels. So, the lack of traction really does manage to direct the flow of energy away from the wheel with grip.
Torsen differentials have a torque multiplication factor, typically around 3 to 1. It means that whatever small torque is seen by the spinning wheel - the other wheel sees three times that torque. As long as you can keep wheel spin down to 30 or 40 percent and stay on a decent surface, you should get enough bite to allow the other wheel to drive. Large amounts of slip, ice, oil, or a wheel in the air will all turn a TBD into an open diff. Under normal circumstances, just letting up a little on the throttle will get a TDB to bite again.
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Senior Member
Ya see, you learn somethin every day.
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Senior Member
I was really impressed with my Modena on the track. It's my first non plate type LSD (TBD)
Thanks- Chad
818R-SOLD!!!- Go Karted 7/20/14/ Officially raced NASA ST2- 2/28/15
2016 Elan NP01 Prototype Racecar Chassis #20
1969 Porsche 911ST Vintage Race Car
1972 Porsche 911T (#'s matching undergoing nut & bolt resto in my garage)
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Senior Member
The more I read this stuff, the more my brain hurts........
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Research Calibrator
Originally Posted by
FlatironsTuning
One thing to keep in mind is that if you are running a Cusco or clutch type differential, you need to run at least a quart or two of fluid formulated for a limited slip additive, you may see more popping noise from the clutches in the differential.
When we ran the Cusco differential in our Rally Car, we would run a couple of quarts of Redline Shockproof gear oil with our normal transmission fluid, and that seemed to work best.
I was just about to put fluid in my Andrewtech PPG 5 speed with a Cusco 1.5 front LSD. Since the oil is the same for the diff and the transmission, I assume you have to pick some kind of compromise.
I was going to use Motul 300, but am wondering if I need to mix in something with LSD additives? I could use some of the Motul 300 LS ( which is the LSD version ). Perhaps 50/50 of each?
I would be hesitant to use the Shockproof in the transmission, as it is specifically designed for differentials not syncros and the like.
Jeff
Last edited by sponaugle; 04-26-2015 at 11:25 PM.
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Senior Member
Originally Posted by
sponaugle
I was just about to put fluid in my Andrewtech PPG 5 speed with a Cusco 1.5 front LSD. Since the oil is the same for the diff and the transmission, I assume you have to pick some kind of compromise.
I was going to use Motul 300, but am wondering if I need to mix in something with LSD additives? I could use some of the Motul 300 LS ( which is the LSD version ). Perhaps 50/50 of each?
I would be hesitant to use the Shockproof in the transmission, as it is specifically designed for differentials not syncros and the like.
Jeff
Jeff, I've used Shockproof with my PPG gearset and syncros for years. The cocktail recommended from Andrewtech was 3 quarts Lightweight shockproof and fill the rest with Motul 300.
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Senior Member
Originally Posted by
sponaugle
I was just about to put fluid in my Andrewtech PPG 5 speed with a Cusco 1.5 front LSD. Since the oil is the same for the diff and the transmission, I assume you have to pick some kind of compromise.
I was going to use Motul 300, but am wondering if I need to mix in something with LSD additives? I could use some of the Motul 300 LS ( which is the LSD version ). Perhaps 50/50 of each?
I would be hesitant to use the Shockproof in the transmission, as it is specifically designed for differentials not syncros and the like.
Jeff
For what you paid for that transmission, I think it would be cheap insurance to call andrewtech instead of asking on the forums. BTW, how much power do you plan to put through that thing?
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Research Calibrator
Originally Posted by
STiPWRD
Jeff, I've used Shockproof with my PPG gearset and syncros for years. The cocktail recommended from Andrewtech was 3 quarts Lightweight shockproof and fill the rest with Motul 300.
Interesting. I too have used Shockproof in my Subaru transmission, but more recently it seems people have moved away from it. Like many things the reasons may be entirely anecdotal, not based on any good science. Motul also makes an LSD fluid (Motul 300LS). I dug around and the spec/install information from Cusco mentions this particular problem ( having the diff in the same fluid as the transmission). They suggested that if syncro life is more important, use a fluid like Motul 300. No mention of Motul 300LS.
Originally Posted by
Canadian818
For what you paid for that transmission, I think it would be cheap insurance to call andrewtech instead of asking on the forums. BTW, how much power do you plan to put through that thing?
Indeed I sent Andrew an email last night as well, so I'll post back what he says. I suspect in the end there will be some compromise between the LSD and the syncros. I would favor the syncros, as I can remove and service the LSD myself.
As for power, I plan on using the TS-GT4088 on the EZ30R sleeved bottom end with the new ported heads and cams I just got from Cobb... so I would guess 650whp or so. I have a second sleeved block and heads that I am going to swap into my 2002 bugeye to develop the maps on.
Jeff
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Senior Member
It is well known in the Porsche racing circles NOT to use a gear oil with any type of LSD additive in a gearbox WITH a plate type LSD. It defeats the purpose of the LSD on the track.
I don't run a LSD additive with my Plate LSD in the 911, I have not for over 10 years. My LSD has yet to need any plates replaced in that time-frame either (Guard GT LSD). It always is within spec.
I'm using Swepco 201 in my 818R. I have used it in the Porsche for 10+ years. Its always been great.
Last edited by C.Plavan; 04-27-2015 at 12:32 PM.
Thanks- Chad
818R-SOLD!!!- Go Karted 7/20/14/ Officially raced NASA ST2- 2/28/15
2016 Elan NP01 Prototype Racecar Chassis #20
1969 Porsche 911ST Vintage Race Car
1972 Porsche 911T (#'s matching undergoing nut & bolt resto in my garage)
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Senior Member
Our OBX (Gear type) with upgraded bolts and some cleanup has worked well in parking lot driving as well as well over an hour of auto-x race pace driving. We never light up one rear wheel without the other on corner exit, and we have had no issues with odd behavior at low speed neighborhood or paddock driving. We're satisfied!
-Andrew
Building 818S/R #297 with Tamra
08 Mazdaspeed3 | '12 F800R | '97 Miata
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Research Calibrator
Originally Posted by
C.Plavan
It is well known in the Porsche racing circles NOT to use a gear oil with any type of LSD additive in a gearbox WITH a plate type LSD. It defeats the purpose of the LSD on the track.
I don't run a LSD additive with my Plate LSD in the 911, I have not for over 10 years. My LSD has yet to need any plates replaced in that time-frame either (Gaurd GT LSD). It always is within spec.
I'm using Swepco 201 in my 818R. I have used it in the Porsche for 10+ years. Its always been great.
Cool Chad. Thanks for the info. I have heard that Swepco 201 is good, especially in the Porsche world... and it is cheaper then Motul 300 by a bit. Hmm.
Jeff
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Research Calibrator
Originally Posted by
STiPWRD
Jeff, I've used Shockproof with my PPG gearset and syncros for years. The cocktail recommended from Andrewtech was 3 quarts Lightweight shockproof and fill the rest with Motul 300.
Bingo. Andrew emailed me back and said:
---------- Forwarded message ----------
From: Sales Andrewtech <[email protected]>
Date: Mon, Apr 27, 2015 at 10:41 AM
Subject: Re: AWESOME 818
To: Jeff Sponaugle <[email protected]>
Hi Jeff!
I would highly recommend 2 qts of redline lightweight shockproof and 1 quart of motul gear 300. To be honest though it's probably going to take little less so be careful not too overflow
thanks
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Senior Member
^^ I love the subject line "AWESOME 818". I guess the new LSD takes up more volume so you need less trans fluid - good to keep in mind.
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Senior Member
For street driving and autocross the Quaife, OBX Clone, Torsen style works very well. I have a crude clutch type in my Silverado, low speed noises and jumps bother my wife to no end... In such a light car I'm sure some adjusting would be desirable for a clutch type, they are best suited for racing.
Dan
818S #17 Picked up 8/1/13 First start 11/1/13 Go Kart 3/28/14
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Research Calibrator
Originally Posted by
STiPWRD
^^ I love the subject line "AWESOME 818". I guess the new LSD takes up more volume so you need less trans fluid - good to keep in mind.
More so because we remove the center diff and the rear housing That is almost a qt back there.
Jeff
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I can shed a bit of light on to this subject, if it helps. A plate type differential such as the OEM, Cusco, and OBX are all designed with a certain amount of pre-load that holds the plates (clutches) together. This ranges from differential to differential, some higher than others. This is the binding sound you hear in some on slow turns. This is called break away, and completely normal. There is NO danger of the differential completely locking up in your car unexpectedly. You do not see or hear this with the quaife because it is not a true limited slip differential. The are torque biased differentials, and while they do give some help, are quite different in their operation.
OS Giken makes a very good plate type differential that has a very low pre-load internal to them which means that they create less noise on slow turns. It is currently available however for only for the STI gearboxes. Cusco does make a version similar to the OS Giken as well. Oils can make a bit of a difference when it comes to slow turn in noise, but there are some issues with premature synchronizer wear if you use a oil that is too slippery.
For those of you that have a safety concern regarding installation of a LSD already in your car, or one you might be thinking of adding to it, keep in mind that LSD's for the most part have not changed in since they were originally invented by Porsche over 60 years ago. They greatly improve the handling characteristics of most cars, and as such can be found in near EVERY real sports car. There is no real safety issue to be concerned about unless you start tinkering with the internals without knowing what you are doing. The biggest reason that car owners, and builders use the plate type differentials over the TBD diffs, is due mostly in part to the ability of the differential to give lock up on the deceleration side of the differential, as well as, naturally, to the accel side. This allows for greater control during breaking, as well as deeper entry into turn with greater control and speed. If you are building a car for the track, and you want to get the most out of it, then a plate type LSD is what you want to have. If you are only driving on the street and want a slightly better feel for the handling around turns, run with the Quaife style.
I would be happy to discuss the benefit of either in more detail if you like, but this should help at least a little bit. To say that there is some kind of safety issue with running a LSD in these cars, however, is simply not true, and is a bit irresponsible in my opinion, as a good LSD tends to add safety, NOT detract from it.
Happy building all,
Erik Johnson
The Race Line
(970) 344-7761 phone
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The OBX is not a plate type.
fred
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Senior Member
I can tell you the OS Giken unit has a horrible reputation in the Porsche, Mini, Honda circles.
Last edited by C.Plavan; 05-01-2015 at 09:04 AM.
Thanks- Chad
818R-SOLD!!!- Go Karted 7/20/14/ Officially raced NASA ST2- 2/28/15
2016 Elan NP01 Prototype Racecar Chassis #20
1969 Porsche 911ST Vintage Race Car
1972 Porsche 911T (#'s matching undergoing nut & bolt resto in my garage)
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Originally Posted by
xxguitarist
Our OBX (Gear type) with upgraded bolts and some cleanup has worked well in parking lot driving as well as well over an hour of auto-x race pace driving. We never light up one rear wheel without the other on corner exit, and we have had no issues with odd behavior at low speed neighborhood or paddock driving. We're satisfied!
what fluid are you using??
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Senior Member
Originally Posted by
Samiam1017
what fluid are you using??
We used Uncle Scotty's Cocktail. Our transmission was out of an 02 WRX. It seems to be working just fine, although we'll likely switch to the OEM Subaru stuff (Extra-S) for simplicity later.
Tamra
Building 818SR #297 picked up 10/25/14 with Andrew (xxguitarist)
First start 12/21/14,
First "drive" 1/17/15
First Dyno at EFI Logics 3/7/15- 310whp at 15psi for break in, full spool by ~3500rpm!
First autocross 3/29/15
1st Registered 818 in Connecticut 7/24/2015. 9 months - 1 day from kit pickup!
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Senior Member
Well it's been a few years since this was discussed. Looking for any updates or additional input on differentials. My trans will be split soon, which would be the time to upgrade if I was going to. I'm reading here that a gear type would be more appropriate for my 818 given primarily street miles with some track time here and there.
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Moonlight Performance
I like my Quaife. Expensive but strong and works great on the track, street, and strip.
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Senior Member
Originally Posted by
Hindsight
I like my Quaife. Expensive but strong and works great on the track, street, and strip.
2nd vote for the Quaife unit. Mine is all track mileage and I have no complaints / problems. The Quaife unit has the added benefit of fitting the 6 speed transmissions should you ever want to upgrade.
That's what I'm doing this winter.
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Another vote for Quaife if starting from scratch....
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