JDM rear suspension

[SoobyDoobyDoo]

Has anyone done this, or know much about it (or know who is still around who has)Or was it ever really discussed? Can’t find much. Basically have all the rear JDM aluminum trailing arms and diff cradle pieces. Just wondering if I can get new usdm bushings and put everything back together or if it’s more complicated. Would like to swap over when I re-do the suspension. Thanks in advance for any advice…

[GearJamr]

I have heard there is an issue with the usdm abs module connecting to the jdm trailing arms.  AFAIK it would involve splicing the jdm module to the usdm wiring, but don't quote me.  That was the reason I sold the jdm arms I had and picked up some usdm spec.b arms.

 

[KZJonny]

I have the trailing arms and aluminium control arms only. Speed sensors had wires cut, but no problem installing USDM versions....

You need some adaptors from Cusco, since there is nowhere to mount a sway bar endlink unless yours came with the Spec B type brackets still installed. In which case you also need the odd Spec B swaybar.

Don't know anything about the diff cradle, but I would very much suspect the bushes would all be the same? Probably the serious JDM ones would be metal bushes tho, no?

Edited October 7, 2022 by KZJonny
Sent from my phone… ugh.

[seanyb505]

Use just the aluminum pieces, no need to worry if they come with any wiring. Usdm speed sensor bolts up fine. Make sure you have the bracket as mentioned. It's shown in spec b part diagrams. No real need for cusco stuff unless you will sleep better with it on. 

Any Legacy sway bar should work, I've not heard of a spec b specific sway bar. 

All usdm bushings work. There's really nothing magical about the jdm pieces, at least that I found when swapping it all in. 

Edited October 7, 2022 by seanyb505

[SoobyDoobyDoo]

Cool thanks for the responses everyone. Was wondering if it was a mostly bolt-in deal. I was planning on getting all new bushings anyways. I can do wire splicing that’s not a big deal if needed. I figured the spec b should be the same as a standard GT? I’ll have to check out the spec b sway bar endlink bushing, thanks for the info! Will the usdm one work or does it need to be JDM? Thanks

Edit: I’ve got avo rear sway bar brackets- would this work?

Edited October 8, 2022 by SoobyDoobyDoo

[KZJonny]

I think I must have been under some kind of impression that the JDM Spec B endlink bracket was unique somehow. Seems not?

So, if just depends on how complete the kit you got was. Around me, they mainly seem to come with the swaybar and mounting brackets sold separately, so I had to get my own (cusco) brackets, then got the mounting point reinforcements at the same time, since it all had to come from Japan anyway. Fits my aftermarket swaybar just fine now. Had to drill a new hole to make the support brackets work, but not a big deal there.

traildogck on outback.org apparently makes then as a direct fit for usdm cars, if needed.

[Infosecdad]

The USDB rear trailing arms have a built-in bracket for the endlinks, the aluminum trailing arms (at least from japan) do not have a built-in bracket, it's a separate piece. 

I bought the Cusco set of reinforcement for the swaybar brackets and they came with reinforced endlink brackets as well, which I can't use until I go to aluminum rear trailing arms.

[SoobyDoobyDoo]

Idk…I wouldn’t think it would be, but I have no idea…seems like there’s all sorts of little nuance things that are different between JDM and usdm models to make doing anything a pita lol. I’ve seen his kits…but gotta be honest, looks like some lowes/home depot angle stock w/holes cut to size…I can do that myself. Also tried to get a hold of him about some front sway bar bushings he sells and no response, so don’t get a warm fuzzy feeling about that avenue. Just my experience. 
 

Good to know about the Cusco stuff…don’t have to have Cusco necessarily but if they make stuff that’ll work then that’s what I’ll use. All good info thanks again everyone!

[SoobyDoobyDoo]

By chance does anyone know the part # for the spec b bracket? Found the Cusco but wanted to see what I could get the stock bracket for…

[KZJonny]

Don't have a stock part number, but FWIW it's worth considering getting Cusco part # (if you go with Cusco)

Cusco 684 316 S Rear Harder Sway Bar Bracket

The "S" is the important part, it is the kit which has the sway bar brackets AND the pointing point reinforcment plates. Maybe you'r already on it, but the price is a lot better for both as a kit than seperately, and why not. The bracket seems to be a weak point..... You DO need to drill a new hole in either it, or the brackets tho, spacing of the bolts holes is not the same between JDM/USDM.

[Infosecdad]

2 hours ago, SoobyDoobyDoo said:

By chance does anyone know the part # for the spec b bracket? Found the Cusco but wanted to see what I could get the stock bracket for…

Driver Side: https://parts.subaru.com/p/Subaru_2008_Legacy-25L-TURBO-6MT-4WD-GT-Limited-Sedan/Suspension-Trailing-Arm-Bracket-Left/49229322/20264AG010.html

Passenger Side: https://parts.subaru.com/p/Subaru_2008_Legacy-25L-TURBO-6MT-4WD-GT-Limited-Sedan/Suspension-Trailing-Arm-Bracket-Right/49229321/20264AG000.html

Example from eBay: https://www.ebay.com/itm/334501666204

                                  https://www.ebay.com/itm/334501669358

Yes, the image is a bolt, but those should be the brackets.

[KZJonny]

Hmmm. That price is a good reason to buy OEM.

I'd never considered that they'd be available, and so affordable here. Didn't spent enough time digging in to those, but they're far from the priciest thing I bought in the upgrade project, so meh.

Mine are blue tho!! 

[SoobyDoobyDoo]

Thanks @Infosecdad and @KZJonny! Helps if you search with that right terminology I guess…”rear sway bar brackets” instead of “rear trailing arm bracket” just makes too much sense…. 
 

@KZJonnydid yours bolt right up? From what I’ve read so far the holes don’t match up to the usdm bracket? Might be worth the extra $$ (or a lot of extra….) to have matching holes…

[KZJonny]

The sway bar mounts that affix to the trailing arms were totally fine. Direct bolt up.

The sway bar mounting point reinforcing brackets that mount to the subframe points need a hole drilled to match. That can be in either the cusco part, or the subframe. Easy fix. I’ll take some photos of mine when I have a moment, but you’d figure it out fast enough.

Edited October 13, 2022 by KZJonny

[SoobyDoobyDoo]

Ok thanks, no worries. If you can get some pics I’d appreciate it but like you said, I’m sure once I get in there I can figure it out. 
 

edit: found some pics on Blackhawk japan. I see what you mean now. Might just go ahead and invest in the Cusco kit, seems like it’d be better/easier for install. 

Edited October 13, 2022 by SoobyDoobyDoo

[Cney]

I'm kind of late to the party. But does anyone know what bolt is used on the sway bar bracket trailing arm side? I need six bolts and they look like the same bolts as used to hold the brake lines to the arm but not sure. Can someone give me the part nr or specs of the bolt? Preferably in metric.

I'm probably making this bracket out of steel myself using a lot of photos. The Cusco part is harder to come by and pretty expensive. Plus I should have all the dimensions when measuring the old steel arm and it's not a problem if it's a little off I think.

[KZJonny]

Brake line/abs sensor bolts are M6. Little guys.

It’s been a minute, but the sway bar bracket bolts would have been at least M8. I would say ~20mm or so.

You have the arms yeah? Just measure the depth and thread pitch of the holes. That’ll tell you accurately.

[Cney]

I have the arms yes. And I meant the bolts on the arm between the hub and front bushing. Those are bigger than the ABS sensor one. Had them apart yesterday when I noticed I was missing a bracket for the sway bar, DOH! I'll measure the hole. But as to specs, same kind of stainless, same pitch, same head?

[KZJonny]

I can pull one out tonight and have a look to confirm.

But from memory they are M8x1.25 like everything else on the car.

Flange head bolts, as long as you can make fit.
 

I wouldn’t use stainless for this application as much as I love to replace everything with SS. I would stick to high grade 8.8 or 10.9 steel for anything that actually bears suspension stress. Be cheaper a well, tho you may end up hunting around for the M8 fine thread bolts. Not many places carry them in stock. They’re probably like dollars a piece at Subaru as well.

[SoobyDoobyDoo]

4 hours ago, Cney said:

I'm probably making this bracket out of steel myself using a lot of photos. The Cusco part is harder to come by and pretty expensive. Plus I should have all the dimensions when measuring the old steel arm and it's not a problem if it's a little off I think.

You mean this one? I’ve got a spare coming if you need it. PM me if you want to discuss further.

[Cney]

Thanks for al the help on the bolts. I've been driving a new sway bar end link in a hole and it seems to be going in smooth. That would seem that it's M10x1.5 but I'll have to Investigate further. I'm planning to put in a zinc flaked flange head brake caliper bolt of some car in it. That has to be plenty strong.

 

Goo to know that I could have that bracket. But I have no clue what that's from but it's not what I was looking for. I did some picture comparing and measuring of the Cusco bracket, did some Cardboard aided design and came up with these after a day of using the equipment of our mechanical engineering academy.

[KZJonny]

15 minutes ago, Cney said:

Thanks for al the help on the bolts. I've been driving a new sway bar end link in a hole and it seems to be going in smooth. That would seem that it's M10x1.5 but I'll have to Investigate further. I'm planning to put in a zinc flaked flange head brake caliper bolt of some car in it. That has to be plenty strong.

 

Goo to know that I could have that bracket. But I have no clue what that's from but it's not what I was looking for. I did some picture comparing and measuring of the Cusco bracket, did some Cardboard aided design and came up with these after a day of using the equipment of our mechanical engineering academy.

Looks good!

Sorry, I never got the car in the air like I meant to, so didn't have a chance to look at the bolt size and thread pitch. If you don't find the right donor bolt to confirm, let me know. I woul also guess that the bolts will be 10x1.25 fine thread.

I have several bags of bolts from my local fastenal for when I do jobs and find ones that are garbage and in need of replacing. I don't think I remember ANY 10 x 1.5 on the car, it's almost all JIS type stuff, so ususally fine thread.

 

I can and will lift the car and pull a bolt to confirm as needed.

 

PS - I also don't know what those above Cusco plates are for.... I need to get back underneath the car.

[Infosecdad]

1 hour ago, KZJonny said:

PS - I also don't know what those above Cusco plates are for.... I need to get back underneath the car.

Those are plates needed to attach the end links for the rear swaybar if you are running JDM aluminum trailing arms.

USDM has a built-in mount point.

[Cney]

1 hour ago, KZJonny said:

Looks good!

Sorry, I never got the car in the air like I meant to, so didn't have a chance to look at the bolt size and thread pitch. If you don't find the right donor bolt to confirm, let me know. I woul also guess that the bolts will be 10x1.25 fine thread.

I have several bags of bolts from my local fastenal for when I do jobs and find ones that are garbage and in need of replacing. I don't think I remember ANY 10 x 1.5 on the car, it's almost all JIS type stuff, so ususally fine thread.

 

I can and will lift the car and pull a bolt to confirm as needed.

 

PS - I also don't know what those above Cusco plates are for.... I need to get back underneath the car.

10x1.25 makes more sense. I've found the Subaru parts code but can't find any data on the thread pitch. I'm heading to the parts store tomorrow. I need a new boot on the rear and clamps for the fronts (because those OEM ones tend to leak on these legacy's). I also need a boot for the steering tie rod end because that one's cracked and failed the MOT because of it so I can get a fitting bolt there too. If they're cheap enough I'll buy 1.25 and 1.5 thread pitch bolts.

[KZJonny]

1 hour ago, Infosecdad said:

Those are plates needed to attach the end links for the rear swaybar if you are running JDM aluminum trailing arms.

USDM has a built-in mount point.

Hah! I should know that, since I do have a set of aluminium trailing arms. Been a while since I got the kit to install them tho. Forgot what all is in it….