I was watching a video about the new GR Corolla.

And I started wondering about our cars. I remember that Honda changed the specification for the subframe bolts going to a bigger head, and wonder if that also had an effect on the directness and steering feel. The idea being that bigger head or ribbed or reinforced flange bolts would experience less clamping deflection at the head.

 

Does your car have subframe collars? I added them to mine. I can't say for sure that they made a difference, and maybe it's just wishful thinking, but the car feels "tighter" now.

 

Yeah, and I have the AP2 subframe bolts too. New inner tie rods improved driver feel and stability 100x more than RSFCs.

 

What kind of inner tie rods, OEM or something else? It's one of the few suspension parts of my car I didn't replace...

 

Hmmm now I'm wondering if I should go back and replace some more hardware on my S.
I have an ap1 with a ap2 rear subframe that I installed in 2014. I don't remember it coming with bolts, so I likely re-used my ap1 bolts.
I'm also putting together an order on Amayama rn for my LS400, so it would be the ideal time to order some new bolts.

 

Meegan, good ol Taiwan quality. $50 for the pair when I got them. I think they're like $70 now. I wanted Hard Race ones, but they were on back order, didn't want to wait. My driver side one couldn't support it's own weight when I was replacing the tie rod end, so I replaced it, improved tire wear and made the car less nervous.

 

Never once have I recommended to anyone that a subframe bolt could improve performance. I never will.

Never once have I recommended subframe collars to fix anything.

 

That said, would you rather use the AP2 19mm head bolts or the AP1 17mm head bolts in an AP1 subframe, there must be a reason Honda went to the 19mm head.

 

I will use the ap1 bolts, forever, with confidence.

The bolt diameter is the same. There is no difference except the bolt head.

The change could have been for superceeding, or streamlining logistics for the bolt itself (its nice to use ONE socket for all subframe bolts). I would change them for THAT reason. There is no functional difference.

Wound you like to talk technical about subframe collars?

 

No comment on the collars, I have them, like I said, new inner tie rods made a bigger difference to tightness in the steering than the collars ever did. I have the 19mm bolts on my AP1 subframe, they fit just fine.