Can i put LSD on my 98 Type SH Prelude?
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Joined: Oct 2008
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From: Jacksonville Beach, Florida, United States
How is an electronically controlled diff that is only active under hard cornering and adds weight better than say a 1.5 way that is mechanical, doesn't weigh more than a open diff and is active under both cornering and acceleration?
my mfactory lsd weighs more and you can tell a definitive difference between the OEM and the mfactory when you hold them in both hands.
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For example, a mechanical diff won't know where the steering wheel is pointed, or care. ATTS will. ATTS is also connected with the ECM, and knows a lot of that information as well.
And while I'm sure someone can point out an exception to this (dirt, maybe), you also generally don't want lockup under de-acceleration like you would get with a "1.5 way" diff in a FWD car.
And was pointed out, an LSD will weigh more than an open diff.
I probably should have asked him why he would want to do that before I answered.
And looking back at his question, what would happen if you did put an LSD in a transmission in a car with ATTS?
And looking back at his question, what would happen if you did put an LSD in a transmission in a car with ATTS?
Honda-Tech Member
Joined: Oct 2008
Posts: 1,562
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From: Jacksonville Beach, Florida, United States
I thought they weighed about the same. =/
Pretty sure you cannot put an aftermarket LSD into a ATTS trans though. Another thing though, doesn't ATTS freak out and shut down when the car starts to put down over around 250whp? Seems like that would be a big downside if a car had a serious NA build or boosted.
Pretty sure you cannot put an aftermarket LSD into a ATTS trans though. Another thing though, doesn't ATTS freak out and shut down when the car starts to put down over around 250whp? Seems like that would be a big downside if a car had a serious NA build or boosted.
the back of the block is different on the type sh prelude with the atts. If you did put an lsd tranny in the car, the halfshaft would not bolt up to the block. the type sh h22a4 block was made to bolt the atts unit to the back of it instead of a regular halfshaft. you would need to get a custom bracket or plate made to make the halfshaft bolt up. 
i think i said that correct. if not feel free to correct me.

i think i said that correct. if not feel free to correct me.
the back of the block is different on the type sh prelude with the atts. If you did put an lsd tranny in the car, the halfshaft would not bolt up to the block. the type sh h22a4 block was made to bolt the atts unit to the back of it instead of a regular halfshaft. you would need to get a custom bracket or plate made to make the halfshaft bolt up. 
i think i said that correct. if not feel free to correct me.

i think i said that correct. if not feel free to correct me.

I would have to imagine you could get something custom in there but that would completely break the ATTS's ability to read it's plethora of sensors correctly, wouldn't it? To think about it in as simple of terms as possible, I'd think that ATTS needs one axle to spin more/less than the other to apply the brakes properly.
I don't own an SH so I don't know if the "Active Torque" limiting is done via a set of clutches inside the transmission or done using the wheel brakes similar to most other traction control systems. Everything I've read indicates that the differential in an ATTS acts like it has an open differential when it's sensors are reading equal torque across the wheels and the steering angle/yaw/etc are all zeroed.
ATTS is an lsd, of sorts. It is an actual differential and occupies space, so you can't physically just put another one in without pulling at least some parts of the ATTS out. I suppose you could pull the ATTS unit and throw the internals of a base tranny inside the SH tranny casing and then put an lsd in, maybe?
(edit: and I could believe a story that the SH trans could be set up with a regular differential if you do all the other stuff in "base transmission swap" list, but that's a bit different...and I have no idea if that works or not)


