What about bracing the upper control arm tube in the subframe? We have been doing that for several years.

We were seeing cracks develop in the heat affected zones where that upper tube is welded to the subframe.

 

This is something I never thought to check. I found this crack on the driver's side. The car has 162,000 miles on it. I assume that crack can be repaired, and then the braces added, but would I be better off finding a lower mileage subrame?

Thanks,
.

 

If a crack has already developed, it's too late. Time for another subframe.

The gusset does not reinforce the entire subframe, it merely prevents the crack from forming in the first place

 

Yup. IMO that's a "park the car" failure. Buy a used subframe, add the braces on the workbench, and then swap it in.

If you were thinking about doing an NB subframe, now is the time

 

She is an NB. Serious question... can I remove the subframe without removing the engine if I have a hoist, jacks, trans jack, jack stands, etc.?

 

Sure, yes. I would never pull the engine for just a subframe swap. I would pull all the control arms and the steering rack first, though - IMO it's easier to swap all that stuff with the subframe bolted down to something large and immobile, like a car

 

I guess I got lucky, really. I just put some low-mileage LCAs on, front and rear, so the alignment bolts and such are all still loose and she's still up on jack stands.

 

Is there a trick to getting the engine lined back up? Getting mine back in involved pry bars ratchet straps and cursing. Ended up pulling both motor mounts, but it was still a massive pain in the ***.

Would still do it without pulling the motor if I had to do it today though.

 

​​​​​​What engine mounts do you have? Ever since I swapped to AWR/SPM mounts it's super easy to line the mounts up. They swivel a bit so you can angle them however is needed.

+1 to swapping subframe while bracing engine with it chained to strut tower brace/homemade brace and jack underneath the trans.

One other tip after you get new subframe in. Torque it all down, drive around a bit, and then double check all bolts BEFORE you go get it aligned.

 

OEM mounts. Unless I'm missing something dramatic about the way the Miata front suspension works, pushing the subframe forward only gives you more wheelbase. Every suspension/steering component mounts to it.

 

(ninja edit)

 

Disclosure, I don't recall ever actually doing it that way. I know we swapped a front subframe one of the years at T25, but I either didn't do the lining-up bit, or it was such a nightmare I pushed the memory out of my mind.

I am doing it that way in a few weeks on a customer's turbo NA, and I'll try to remember to stop back by here and say how it went. My plan is to lower the engine about 2", get it bolted to the new subframe, and then use the hoist to lift the whole mess up into the car, pushing front/back/side-side as needed.

 

I found pulling just one motor mount then using the other as a pivot point works best. I did it with the engine installed and found it to be quite easy. I kept drivers side engine mount installed and played with passengers side after.

 

Weld in (or attempt) frame gussets.... check.
Had rather big gap to fill in the valley.

 

That is what I thought as well, but what I didn't think about is that the engine does not move up and down, it pivots on an arc set by the trans mount. Makes the fore/aft alignment a nightmare when the motor isn't at the exact right height.

 

No point in filling that gap. The vast majority of the strength of this brace is in the lower plate, which triangulates the LCA pickup. I'd bet you could get 90% of the benefits of these by just welding a chunk of 1/8" plate. The little side tabs are there to give a little extra material to weld to, and to help properly locate everything. By the time you're up into that gap, you aren't doing anything but dumping heat into the subframe with the welder.

The way I do it:

 

Unbolt the PPF and stick a jack under the back of the trans.

 

I was wondering about that Sav - thanks for the input! However, I didn't know orientation so looked at how Emilio had the Mazda logo - inward or outward... he had his inward, yours is outward... not that it matters - I thought inward looked to be more level.

 

Flyer129 and myself took on the subframe removal after he broke his lower control arm mount. I made a short video on the process we used to remove it. Putting it back in wasn't really a big deal either but he does have AWR (?) mounts on the car.

 

Don't forget to hold your tongue right, it's key to this job.......