Phase 2 Motortrend Rigid Collars for A90 Supra -- Tips, Tricks, Torque

[Thraxbert]

This is concerning the Phase 2 Motortrend (P2M) rigid collar kit for the A90 Supra. I am not compensated by or affiliated with this company.

History: Aside from my Supra, I also have a big turbo Genesis Coupe 3.8 that I've been building for 8 years. The Genesis Coupe has a notorious amount of undesirable subframe movement under high-G maneuvers, such that it's not uncommon for people really building out their chassis setup to loosen the subframe bolts and shove the subframes back into place with a big-ass prybar. After that: rigid collars for the subframe bolt holes, and aluminum shims to fill cavities in the subframe bolt bushings, are not uncommon. Tightens everything up real nice, and my own Genesis ran this setup until I swapped the rear subframe for one from another car with a 5L V8.

It's that as a background that I wondered what the subframe situation looked like on the Supra and if rigid collars would be beneficial. After tearing everything apart and doing the install, I wanted to share my general thoughts and tips on what I found.

1) As a starter, you will need (or should have, to make life easier) the following tools:

• A torque wrench capable of 90 ft-lbs, preferably 1/2" drive for ease of tightening
• Long-handle 3/8" drive ratchet to break the nut, and an electric ratchet to speed removal -- these bolts are very long
• Extenders in 6" and 12"
• The following sockets:
  • 8mm hex for screws securing the plastic splash guards
  • 16mm hex for metal skid plate under the oil pan, plus rear subframe chassis ties (forward tie bolts marked #1, rear tie bolts marked #2)
  • 20mm (maybe 21mm?) hex for two bolts on the front subframe
  • E14 E-Torx to remove two bolts from the rear floor panel brace (#2 marked bolts)
  • E18 E-Torx for 4 of 4 rear subframe bolts, and 2 of 4 front subframe bolts

2) The provided instructions are very poor. Grainy black and white copier printout with no specs, and the bolts you're looking for are hidden by splash guards in their diagram. There's no step-by-step guidance for anyone unfamiliar with this kind of project. In fact, the provided instructions only say "return to factory torque spec" and explain roughly why the collars are numbered. So, disappointed, I dug into what those were and assembled these diagrams for the front and rear.

• Front Subframe, correct bolts + torque (pg 1250 of shop manual) -- note I've hidden the irrelevant bolts so you can better identify what to remove
• Rear Subframe, correct bolts + torque (pg 2070 of shop manual) -- note I've hidden the irrelevant bolts so you can better identify what to remove

3) Each bolt has one appropriate collar. The collars are numbered. The provided instructions will show you which collar goes with each bolt. Cross-reference with the below diagrams.

4) The rear subframe bolts are hidden by plastic splash guards (8mm hex). The front subframe bolts are hidden by the metal skid plate under the oil pan (16mm hex) and plastic splash guard (8mm hex).

5) It's very important that you hand tighten all of these bolts to gently feed the collar into the subframe holes. Some of them will be snug, so be prepared to partially install and remove each bolt several times to inspect the collar, ensuring it's not being marred or distorted. Once you are confident the collar is not being damaged, proceed with full installation. My front driver side subframe collar (E18 bolt) was especially tight, and I legitimately checked this bolt 7-8 times with only a few revolutions of hand-tightening before bringing it up to torque. I also test-fit each collar in the bolt hole in the subframe by inserting the collar by hand, before even putting a bolt in the hole.

6) ONLY REMOVE ONE SUBFRAME BOLT AT A TIME. Do one corner at a time, and fully reassemble it to torque prior to moving to the next bolt.

7) This is a very easy install IF you take the right preparatory steps to remove splash guards, skid plates, and chassis braces before attempting to install a collar. If you have any questions, DM me! Overall, fitment was very good and total time took me about 2 hours inclusive of getting distracted by my phone and a beer break.

8) So, do I need the collars? Hard to say. I don't track my car, but the amount of wiggle room in the holes for the subframe bolts are much bigger than the bolts. I can definitely see this leading to some wobble under motion. Unlike the Genesis Coupe, however, the front Supra subframe has more bolts than the Genesis and the rear Supra subframe has chassis ties at all four corners--the Genesis does not. This extra bracing from the Supra somewhat diminishes the need for collars versus other platforms that are less reinforced. But, still: those bolt holes are mighty big. It's a cheap upgrade to bring some additional rigidity, and that's never so bad!

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[underdonk]

This is a hell of a write-up - thank you! Didn't even know this component was available for our vehicles. Can't say I've ever had to address this on other cars I've put on the track, but it's interesting. Did you by chance get a picture of how much slack is in the hole on the subframe which these bolts fit into without the collars installed?

 

[Thraxbert]

I didn't take a picture, but the diameter of the bore through the subframe easily leaves 2-3mm gap around the perimeter of the subframe bolts.

 

[underdonk]

I didn't take a picture, but the diameter of the bore through the subframe easily leaves 2-3mm gap around the perimeter of the subframe bolts.

Interesting. Thanks for the information. Just to confirm, while you don't track the car, you haven't felt any difference in the car during spirited driving after installation? I know it's subjective.

 

[Thraxbert]

I have not personally felt any difference with spirited driving and I do throw the car around a lot. But, in this case, I wasn't really looking to improve subframe rigidity for the purposes of handling. In this case, I was looking to avoid issues I've experienced with my other car where shifted subframe(s) presented unexpected fitment difficulties with projects I took on down the line.

For example, my Genesis Coupe 3.8L V6 has a big turbo on it. Running the passenger side exhaust collector and the turbo downpipe was unnecessarily difficult because the engine had shifted towards the passenger side and the clearances expected by the hotside piping had disappeared. This also caused issues with running lines for transmission cooling. None of this would've happened if I'd spent the $100 early on in the car's life to collar the subframe, especially the front.

So I consider this an insurance policy for future pains in the ass, and on that front: it will deliver.

 

[METAL]

I had rigid collars on my Genesis Coupe too and did feel the difference. Car moved up and down over bumps in a flatter manner. I heard less cracking in my rear deck over curbs and 3 wheeled more often. Then I did it on the G70 and did not feel the difference but I was on stock suspension.

Is this the best offering for rigid collars or are they all the same?

 

[Funkjaw]

Hey @Thraxbert - any NVH increase from these inserts? How are they treating ya?

These seem like a better alternative to the hardrace kit because they include a top and bottom piece.. although maybe the tradeoff vs the hardrace kit is NVH?: https://www.hardrace.com/Product_detail.asp?id=4820&Car_Make=21&Car_model=65&Car_Type=686&MainType=

 

[Thraxbert]

Hey @Thraxbert - any NVH increase from these inserts? How are they treating ya?

These seem like a better alternative to the hardrace kit because they include a top and bottom piece.. although maybe the tradeoff vs the hardrace kit is NVH?: https://www.hardrace.com/Product_detail.asp?id=4820&Car_Make=21&Car_model=65&Car_Type=686&MainType=

I don't use them anymore, but they lasted until very recently and looked great. No NVH increase. Still not 100% if they're "worth it" but yeah, fine product.

 

[TBK]

I don't use them anymore, but they lasted until very recently and looked great. No NVH increase. Still not 100% if they're "worth it" but yeah, fine product.

Do you mind elaborating on your answer? What happened recently? Why are you not using them anymore?

 

[Thraxbert]

I swapped to a Ford 8.8 differential, solid subframe bushings, solid diff bushings. No ability or need to use the collars any longer.

 

[Funkjaw]

I swapped to a Ford 8.8 differential, solid subframe bushings, solid diff bushings. No ability or need to use the collars any longer.

You crazy son of a bitch!

 

[Happy Polar Bear]

I swapped to a Ford 8.8 differential, solid subframe bushings, solid diff bushings. No ability or need to use the collars any longer.

Hi @Thraxbert, thank you so much for the write up. Is there any NVH increase after you swap to solid subframe bushings? I’m considering doing the same thing - aluminum bushings, but would like to understand the NVH situation first. Also which solid bushing did you use?

Thanks!

 

[marius b58]

I swapped to a Ford 8.8 differential, solid subframe bushings, solid diff bushings. No ability or need to use the collars any longer.

Hello. can you tell me what you put to fill the space between the larger holes in the front subframe and the bolts? I searched Phase 2 Motortrend and didn't find anything for the Supra A90. For the rear axle, I make them myself on a lathe, just like the original BMW ones that are put on the Supra GT4 and the M235i Racing. But I don't understand what you did on the front.

 

[Thraxbert]

Hello. can you tell me what you put to fill the space between the larger holes in the front subframe and the bolts? I searched Phase 2 Motortrend and didn't find anything for the Supra A90. For the rear axle, I make them myself on a lathe, just like the original BMW ones that are put on the Supra GT4 and the M235i Racing. But I don't understand what you did on the front.

The Phase2 collars for the front are still installed, in the prescribed cavities. I continue to question if the front collars are even necessary due to the geometry of the mounting points. As far as I can tell, the angled "wings" that point rearward from the front subframe serve to locate the subframe in a specific position. I don't see how the subframe could meaningfully shift when the main bolts are further triangulated and gusseted in this fashion.

 

[marius b58]

Hi @Thraxbert, thank you so much for the write up. Is there any NVH increase after you swap to solid subframe bushings? I’m considering doing the same thing - aluminum bushings, but would like to understand the NVH situation first. Also which solid bushing did you use?

Thanks!
Hello. I just installed solid aluminum bushings on my car and to me it seems like the biggest upgrade possible on a Supra, especially since it's not expensive. NVH increased very little, after a few days I don't even feel a difference in NVH, but the gain is enormous for those who run the car, a sports car shouldn't have those bushings on the rear axle that move in all directions about 15-20 mm depending on how much you force the car on the rear axle. on a speedway or circuit, with wide curves, the gain wouldn't be noticeably greater, but on a route with tight curves the car is completely transformed, much more precise, when you want to throw it from behind the car does exactly what you ask it to, before the axle would go and then the car would pull after it, now you feel the rear wheels exactly where they are and what they are doing. The difference in comfort is minimal, not even 10%, my car is almost stock anyway, I wouldn't put up with noise or vibrations either. All those who have doubts about NVH, get to work and install solid bushings and you will be super satisfied, it's a huge transformation, especially for those with increased power...

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