15+ STi rack into your GD STi, parts and modification overview!
Hey!... Welcome to #modmonday! Today we will have a more prechecklist/informative post on what parts and modifications you will need to perform to put a 15+ STi 13:1 rack and pinion in your GD/SG Subaru.
Close but not the same. Many small differences make this quite a project.
Quicker faster turning, what's not to love about that upgrade for your car? Especially when it is an oem part.. being that it comes from a newer car with a different overall dimensions it unfortunately won't bolt right in. But this guide will help you figure out what tools, parts and modifications to do so.
First up, if you have your rack removed and are trying to install it in the SG/GD subframe you will notice it won't even make it through the cutouts. The fix for this is to enlarge the holes in your factory subframe and make a few other cuts along the way. Otherwise using a newer VA subframe is an option but you will need to enlarge the subframe mounting holes and you will no longer be able to use your factory lower U-brace.
Factory cutouts won’t be enough for the new rack.
Just another area to cut on the STi subframe on.
After a bit of time with the grinder and burr bit, we have the room we need.
More cutting! Sti subframe.
The SG factory rack installs a bit differently and doesn’t have as many spots to cut and change.
Wider angle shot.
With your factory GD/SG rack next to the 15+ rack you will see how much wider it is. There are many ways to combat this, apparently 06-08 SG inners will bolt in (credit to @danny2shoogs) and shorten the rack width. Otherwise you can cut the 15 rack inners and outers to fit your setup and lastly, you can add 1988 GL outer tie rods which are much shorter and fix the problem.
Factory GD STi at the top and 15+ sti in the lower. It is about two inches longer, which makes it impossible align.
I choose to use factory Subaru GL outer tie rod ends to shorten the rack. This is just one of the many ways to shorten the width of the rack.
Now the rack can make it through the holes but the mounting locations on the rack have changed and won't fit our Gd/SG subframe. At least one spacer(3/8' thick) is necessary to mount it properly. If you head over to where the rack hardlines meet the power steering lines, you will notice they no longer meet. To fix this issue we need to slightly bend our rack hardlines to a better angle, and/or add -An lines.
The factory SG and GD racks are equal on either side. Where the 15+ is offset on the front, a 3/8” spacer is necessary to fix this mounting issue.
These are the longer bolts and spacers to make this job possibly. Yes… Subaru flywheel bearings double as rack and pinion spacers.
The hardlines coming off the 15 Sti rack are very different and need to be modified and/or -AN lines to make these work.
The spacers in action, utilizing the the factory Gd mounting spacer.
You now have the ability to fit the rack to the subframe, attach your power steering lines and bolt in the tie rods to complete the ability to steer. So what else is left? The factory GD/SG power steering pump can run the rack.. but for how long? The 15 Sti rack is normally powered by a more powerful pump than the older racks. So installing a sti 08+ P/s pump will be the next step. If you added those -An lines you are haflways there as you will no longer be able to use the factory lines. The 04+ STi pump bracket will mount it for you, if you don't have this bracket you will need to add it to your list.
08+ STi pump has a higher operating pressure that the 15+ Sti rack needs.
To make this work on your GD/SG you will need to make your own lines as the factory units just won’t line up anymore.
These are what you need to make sure is part of your game plan to install your 15+ Sti rack into your older SG/GD. A full DIy install will be on the way!
Questions, comments, thoughts? Leave them below!