funkytown

Part 3: Hub Selection for 2 pot rears

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Hub Selection for 2 pot Rears – for a V1-6 GC/GF

This is the trickiest part and will require some rework along the way to ensure correct content.

We assume for this swap you have chosen to do a hub SWAP, not the adapter method. If you are doing the adapters this section is not for you.

For the purposes of doing this swap you first need to understand if your car is R160 or R180. For the most part if you want to put on 2pot rears and you do not have them your GC / GF will be R160.

Technical Information

As a point of note you must first understand that brembo 2 pot rear and the smaller ‘normal 2 pot rears’ share the same mount spacing and offset.

To do this swap you need to know what you CURRENTLY have in your car in terms of r160/80 as this determines what you NEED to match. There are options for BOTH r160 based cars and R180 based cars.

Bar 1 (one) exception ALL 1 pot sliding rear callipers have a WIDER spacing than 2 pots – this is about 180mm from memory. 2 pot rears have a SMALLER ~160mm bolt spacing for mounting. (v3 STI RA is the exception (perhaps also v3 sti R to be confirmed) but to be discussed later).

So.. First we need to work out from v1-6 for wrx / sti / r / ra and sedan and wagons what each car got in terms of r160/80 and bolt spacing on hub from factory. We will cover this below.

Hubs that CANNOT be used for 2 pot rears.

For ALL v1-6 wagons and sedan WRX’s:

These have r160 hubs, but the WIDE bolt spacing.

For V1-6 STI wagons and sedans:

These have r160 hubs, but the WIDE bolt spacing.

For v2 STI RA (no type R):

These have r160 hubs, but have the WIDE bolt spacing.

For v3 STI RA and R:

Note: v3 sti ra / r is the ONLY totally oddball rear end in Subaru history.

These have R180 hubs, but have the WIDE bolt spacing. and bothered up oddball rotor sizing (but irrelevant in context of 2 pot rotors..)

Hubs that CAN be used for 2 pot rear conversion on an R180 car ONLY.

For v4,5,6 STI and R:

These ALL have R180 hubs, and have the narrow bolt spacing. (These hubs all take 2pot rears from factory).

NOTE: these hubs are all non ABS so will not suit the majority of cars – expect to go on a v3 STI RA / R that is also non ABS and DOES NOT have 2 pot rears from factory.

At this point you may wonder how you can put 2pot rears on a R160 car, thus:

Hubs that CAN be used for 2 pot rear conversion on an R160 car ONLY.

Fortunately for v7/8 WRX (not considering v9+ due to PCD change) [/u]

have r160 hubs AND they have the narrow bolt spacing (these also come with 2 pot rears from factory).

Also worth noting in this selection process.. the r160/80 hub selection will determine the handbrake shoe diameter. This affects which rotor you chose for 2 pot rears:

For a r180 based set up you pick a rotor normally for a v4/6 STI RA or R.

For a r160 based set up you pick a rotor normally for a V7/8 WRX (not STI).

When selecting the correct rotor for a brembo rear set up:

For a r180 based set up you pick a rotor normally for a v7/8 STI

For a r160 based set up you pick a special rotor made my DBA. (this has the full 316mm diameter but gives you the required smaller handbrake shoe size).

Note you can get a brake place to insert a plate in the v7/8 STI type rotor to make the drum smaller to accommodate an r160 handbrake shoe as an option. In my opinion when i did it - the cost of this on top of the normal rotor cost was similar to the rotor cost of the DBA option.

Using Adapters to run 2 pot rears - (instead of doing the hub swap)

You can get adapters to run 2 pots! Yes! The key here is you use the adapters on any R160 hubs with the WIDE bolt spacing. They dont work as far as ive seen on the R180 hubs.

Basically use these on any V1-6 WRX or standard v1-6 STI with r160 and the V2 sti ra. It will not work on R's or RA's of any year, nor V7/8 wrx (obviously).

To fit appropriate rotors follow the rotor selection pattern as normal above.

The required rotors size are as follows

[table]

[tr][td]2 Pots[/td][/tr]

[tr]

[td]Diam.[/td][td]O/A Height[/td][td]Orig thick[/td][td]Min. thick[/td]

[/tr]

[tr]

[td]290[/td][td]67.5[/td][td]18[/td][td]16[/td]

[/tr]

[tr][td]Brembo rears[/td][/tr]

[tr]

[td]Diam.[/td][td]O/A Height[/td][td]Orig thick[/td][td]Min. thick[/td]

[/tr]

[tr]

[td]316[/td][td]67.5[/td][td]20[/td][td]18[/td]

[/tr]

[/table]

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Just to let you know Jon. The v3 type r is also oddball. Another possibility for the brembos rear brakes on 170mm hand brake is to get race brakes to fit thick shoe material on so can use 190mm drums which is good if you wear them lots.

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yes correct that is an option i was aware of but have omitted. Will include.

Great - so v3 sti R is the same as RA in that it has solid rotors + single pot side calipers.

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updated from PM by B4 2000 and my reply to him, points to add to and require clarification.

 B4 2000 said:

just a quick note,

Ya it seems i was wrong in thinking V5-6 STI has 290mm rear disks (as the legacy had the 290mm from MY99-on so i assumed the respected STIs had the same), however wrx recieved the 290mm disks from v7 onwards and its the same wether v7-8-9-10 etc as the wrx remains the 5x100 stud pattern << Only STI went to 5x114.3 NOT wrxs

I havent focused on the factory rotor specs.. But regardless i do not think any of the single side pot rotors are the right diam / thickness / offset for 2 pot rears. From what you are saying though i think you imply that MY99 LEGACY rotors are the correct size for 2 pot rears (Innnnteresting).

That said it would be good to do a measure up (read:confirm) and add it to the information model. Putting in the exact rotor measurements of the 2 pot and brembo rears would also be useful.

You are correct on the WRX hubs PCD actually. However thinking about it - perhaps worth note is that the suspension geometry went up the s*** from 9 onwards (with respect to the GC arrangement) so would need investigation as to how much changed in the rear. For sure the v10 rear end is different.

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I have emailed you brake rotor catalogues for specs. Do the fancy copy paste thing that you know how to do.

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 funkytown']

updated from PM by B4 2000 and my reply to him, points to add to and require clarification.

[quote name='B4 2000 said:

just a quick note,

Ya it seems i was wrong in thinking V5-6 STI has 290mm rear disks (as the legacy had the 290mm from MY99-on so i assumed the respected STIs had the same), however wrx recieved the 290mm disks from v7 onwards and its the same wether v7-8-9-10 etc as the wrx remains the 5x100 stud pattern << Only STI went to 5x114.3 NOT wrxs

/quote]

I havent focused on the factory rotor specs.. But regardless i do not think any of the single side pot rotors are the right diam / thickness / offset for 2 pot rears. From what you are saying though i think you imply that MY99 LEGACY rotors are the correct size for 2 pot rears (Innnnteresting).

That said it would be good to do a measure up (read:confirm) and add it to the information model. Putting in the exact rotor measurements of the 2 pot and brembo rears would also be useful.

You are correct on the WRX hubs PCD actually. However thinking about it - perhaps worth note is that the suspension geometry went up the s*** from 9 onwards (with respect to the GC arrangement) so would need investigation as to how much changed in the rear. For sure the v10 rear end is different.

Just for confirmation all gtb and rsb has the 290mm disks. So if you got a gtb and adaptors with 2 pots it will bolt on.

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yup i have the catalogue here Jase. I might go through it more carefully and work out which factory rotors also correspond but at a glance looks to be BE/BH legacy onwards.

And v7/8 WRX onwards.

updated with correct rotor size required for each

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not by my spreadsheet.. some have the 290mm disc, but are much less thickness.

not that spreadsheets are the truth, but its what i have in front of me.. BG is also r180?

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Can confirm single sliding calipers and solid rotors on the rear of my v3 sti ra. Awesome write up too as I was pondering 2 pot rears as well

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 funkytown said:

For a r160 based set up you pick a special rotor made my DBA. (this has the full 316mm diameter but gives you the required smaller handbrake shoe size).

Note you can get a brake place to insert a plate in the v7/8 STI type rotor to make the drum smaller to accommodate an r160 handbrake shoe as an option. In my opinion when i did it - the cost of this on top of the normal rotor cost was similar to the rotor cost of the DBA option.

There is a less costly way of doing this and thats run extra thick shoes as i done my own, From memory its 171mm vs 191 E-brake so you get custom shoes made up. I got 14mm of meat put on each shoe.. thats 4mm for factory thickness and extra 10mm each shoe gives you 20mm extra which is what you need to match the brembo 191mm e-brake. It cost me $120 to get the shoes made up and does the job nicely.

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 funkytown said:

not by my spreadsheet.. some have the 290mm disc, but are much less thickness.

not that spreadsheets are the truth, but its what i have in front of me.. BG is also r180?

As with most manufacturers there are bound to be odd exceptions. Those catalogues should be relatively right but I normally match to size not model to be sure.

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 funkytown said:

not by my spreadsheet.. some have the 290mm disc, but are much less thickness.

not that spreadsheets are the truth, but its what i have in front of me.. BG is also r180?

Nope legacys are r160

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then this means the legacy rotors are not the same as factory 2 pot rear rotors on v4/6 STI R and RA's as the shoe size will be different but the same as v7/8 WRX rotors.

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 dzk said:

Can confirm single sliding calipers and solid rotors on the rear of my v3 sti ra. Awesome write up too as I was pondering 2 pot rears as well

have just done this on a v3 sti RA.. the best option for you being that you have NON ABS hubs and R180 from factory is to find a set of v4/6 sti RA or R rear hubs.

Using v7/8 STI hubs will have ABS rings etc and may get picked up at WOF time.

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 funkytown']

[quote name='dzk said:

Can confirm single sliding calipers and solid rotors on the rear of my v3 sti ra. Awesome write up too as I was pondering 2 pot rears as well

/quote]

have just done this on a v3 sti RA.. the best option for you being that you have NON ABS hubs and R180 from factory is to find a set of v4/6 sti RA or R rear hubs.

Using v7/8 STI hubs will have ABS rings etc and may get picked up at WOF time.

Note that many new cv joints come with abs rings now to suit abs and non abs apps in one hit... Guessing its ok wof time.

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 funkytown said:

yup i have the catalogue here Jase. I might go through it more carefully and work out which factory rotors also correspond but at a glance looks to be BE/BH legacy onwards.

And v7/8 WRX onwards.

updated with correct rotor size required for each

i also herd that about the BE/BH gtbs but when asked on here was told not so, but its only the rotors on them that would fit a ver5 sti

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yes the hubs are totally different as the suspension setup is all different. From the catalog i have though the rotors are still correct.

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When I did my conversion on my BE, Im sure BNT had a rear disc rotor that was same as V7+ Brembos but had the smaller handbrake drum....

The Adaptor Kit I got from japan came with large rings which you would press into the brembo rotor drum to get the correct size.

Also Theres a thread on a BE/BH 2pot conversion I posted some pics which show how different the BE/BH rear hubs are to the WRX hubs.

EDIT* Ive got a thread from a few years ago which someone did a Conversion on a BE/BH. I'll post it up in one of these threads and you can edit to suit if you want. I dont have the pictures anymore, but still have a few pictures about the conversion.

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im in the process of converting my bp5 rear brakes to brembo 2 pots off from v7 sti. already have done the front ones. will let you guys know how it goes. will post some pictures once its done.

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so if i was to bolt a r180 into a 1998 subaru rwd wagon, i would want to use the v3 sti ra / r hubs to keep the factory brakes single pot sliders? :D random job for a guy

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