Learn me checking for bent unibody/Suspension

So i think my miata ia bent. The rear had an inch of toe out with the eccentrics centered, all on the drivers side. Passengers was perfect. Front had a half inch, passengers side.

I know the car has a salvage title, and it was hit on the passengers front corner. I was told that the frame had been straightened. I can still see slight deformation in the drivers frame rail, but everything else looks good. Doors and decklid line up and shut perfect. Front sheetmetal doesn't line up worth a damn yet, but thats because the core support is still wonky.

Its a rist free California car with 85k and pefect drivetrain and interior.

How do i go about seeing if the unibody is bent still, if its subframe damage, etc? Im already 2500 deep in this thing, and don't want to get in any deeper than that if its done for. But if its just a control arm/subframe thing, im game.

So, how do i figure it out?

Toe change like that is going to be because of something in the suspension, not the body. I would guess bent upright since they look awfully weak to my eyes. Toe control is by H-shaped lower control arms and you're not going to bend one of those in a way that only changes toe.

Use a Mark 1 Index Finger and measure the gap from the control arm bushings to the wheel lip.

Don't worry about bent chassis rails if the doors open and close properly and such. That can happen just from someone putting a floor jack under the middle of the car to lift up one side at a time. 22 gauge origami isn't as strong as some people think it is.

It needs to go on a frame rack and get properly measured. It might be possible to measure it just up on jack stands, but if you don't have all the dimensions for reference you might be wasting your time. Do you have a good body shop that can check it for you?

Should have made clear that the deformation is in the front, ahead of the suspension, near the swaybar bracket.

The passengers side rail under tje floorpans obviously was drug on something, and now thining about it some more, tbe front eccentric boss on the passengers side front corner is deformed and obviously scraped by whatever got the framerail.

Im hoping not to have to pay my local shop 100 to have them check it, if i can help it. I know hes a rock star with his frame rack, but i don't want to dump even more on what might wind up being a parts car. Im kind of scared and worried about financial ruin at this point.

I'm with Knurled. When I got my Miata it had 2.8 degrees of negative camber and 2.5 degrees of toe-out. Took both rear spindles off, measured them up on a surface plate and the bottom of the one was pretty tweaked. My car had also been wrecked and had had a new front end grafted on, a bent LF upper control arm, no belly pan, a bent wheel and mashed "framerails". Put a new rear spindle and wheel bearing on, replaced my stripped eccentrics and it fell right in line

Google "cross measure". There will be holes in the frame rails that are the same from side to side. A tram bar is the proper tool, but a tape measure and a friend will come close. Pick a spot on the left side, and measure the distance to, say, a control arm mount on the right. Now measure from the corresponding spot on the right to the control arm mount on the left. Measurement should be the same. If you want to get serious, you should be able to google a datum chart for the car.

If you crossmeasure the crossmember mount bolts, the control arm mount, then the ball joint, you should be able to science out where the bend is.

Will a tape measure be good enough, or do i need to get something more accurate like a build table, plumb bob, etc? My main concern is wether its a parts car or not.

All cars will measure "off" an eighth here, a sixteenth there, a tape measure is fine.

Be careful with your mrasurements, and you will get the right answer with any system. Tape measure will be fine.

Well, im stumped. Spent the last hour with the car on the 4 post lift, and measuring everything in every way i can think of. Cant find anything more than 1/8 off. So, im either incompetent, or its not locatable from below with a tape measure and eyeball.

What is the next step?

Bent knuckles/spindles/arms.

Don't worry too much about the "framerail" being squished. They're not actually very strong.

If you do have to replace the rear subframe, it's really not hard. If I had a lift, I'm pretty sure I could do it in a day. Even in the driveway, it wasn't a huge deal.

I remember once seeing a setup using a beaded chain with a weighted plumb bob in the center.

hooking multiple chains across the chassis counting the links to maintain centering and then sighting down the line of plumb bobs.

Between that and measuring up off a flat frame rack to check for twist and the previous checks for square, should enlighten.

I'm pretty certain it's a rear knuckle. It doesn't take much to make them go way out, like 0.050". You're having the exact same problem I was. The actual knuckle was visibly bent but the bolt that held it to the control arm was.

Is there any way to confirm prior to purchase and dissassembly?

Going to call my buddy Bill on lunch break tomorrow and see if he still messes with the frame machine at his body shop. Fairly certain that if he does it, itll be free. If he has one of his employees do it, ill be paying money.

Or would a competant alignment shop be better?

Or should we focus on the spindle?

Im fairly certain that after checking everything closely today that its not a parts car. Its a slightly bent component in the suspension.

I don't know, Duster, I spent some $300 odd on the Starlet, only to come home and mess it all up. You're pretty sure the problem is at a certain wheel, right? (drivers rear, if I'm reading right) I'd start disassembly, and look for tell tale rust, pinches, and buckles. Start guessing, and throwing some parts at it. If the parts car comes through, there's your parts. I'd be inclined to get good used stuff from somebody on here. Throwing money at it sucks, but you're already in this deep...

Is it Treasure Coast who parts miatas out? How about the guys who helped get the ro-miata back together? Edit, one and the same.

Try a string alignment to check?

I think with a little disassembly you should be able to see what is bent. With what you are describing, seems like a control arm or the knuckle to me. You should be able to see where the rear subframe bolts into the body and look for wrinkles and the same for the subframe.

Went by the body shop just a minute ago. Was recommended that i go to the good alignment shop first, as apparently bill has had luck with him straightening suspension out even when slightly bent. He said if its frame bent, hed hook me up.

Im going to follow through for due diligence, but im fairly certain that the spindle is bent.

My MR2 was wrecked, I wracked my brain trying to find the bent spot. It was the upright. I coudn't see any visible bend, even comparing it side by side to the new one.

If others have suggested it I would bet on that as well.

Alingment shop claims subframe. Im not convinced. Local guy parts these cars out. Think im going to rip it apart and compare all the passengers side stuff to known good parts. I just cant believe that the subframe is the culprit. The parts guy in Concord says probably the bolt through the lca and upright.

I had an alignment shop say they couldn't align a C3 Corvette because it had bad rear upper ball joints.

I will be SOOOO happy when we get into our new building and I can do my own alignments.

Dusterbd13 wrote: Alingment shop claims subframe. Im not convinced. Local guy parts these cars out. Think im going to rip it apart and compare all the passengers side stuff to known good parts. I just cant believe that the subframe is the culprit. The parts guy in Concord says probably the bolt through the lca and upright.

I agree on the LCA long bolt. Only way to really know is drive that thing out & have a replacement on hand. Because you'll need a big hammer & will have a tough time getting that sucker out. While you're down there stick a straight edge across the inner LCA mounts to confirm they're not tweaked. They deform from the same hit that bends the long bolt at the other end. Good luck!

Knurled wrote: I had an alignment shop say they couldn't align a C3 Corvette because it had bad rear upper ball joints. I will be SOOOO happy when we get into our new building and I can do my own alignments.

Side note, I will too. I called several shops and told them i had a 54 chevy with mustang 2 suspension that i needed aligned. "We won't touch it(CLICK)"

Control arm bolts sounds likely as you've still got give in the bushings. I did have a subframe collapse at the control arm mounts once on a car I bought that was curbed hard, that was a stamped steel frame. Not sure what miata subs are made from but it conceivable. I think it'll probably be obvious if bolts are bent when you try to remove them

patgizz wrote:

Knurled wrote: I had an alignment shop say they couldn't align a C3 Corvette because it had bad rear upper ball joints. I will be SOOOO happy when we get into our new building and I can do my own alignments.

Side note, I will too. I called several shops and told them i had a 54 chevy with mustang 2 suspension that i needed aligned. "We won't touch it(CLICK)"

One great thing about my dealership job: weekdays after 5pm or all day Saturday I can bring my junk down to the shop and have full access to our Hunter tire machine, Road Force balancer and alignment rack.

Dashpot wrote:

Dusterbd13 wrote: Alingment shop claims subframe. Im not convinced. Local guy parts these cars out. Think im going to rip it apart and compare all the passengers side stuff to known good parts. I just cant believe that the subframe is the culprit. The parts guy in Concord says probably the bolt through the lca and upright.

I agree on the LCA long bolt. Only way to really know is drive that thing out & have a replacement on hand. Because you'll need a big hammer & will have a tough time getting that sucker out. While you're down there stick a straight edge across the inner LCA mounts to confirm they're not tweaked. They deform from the same hit that bends the long bolt at the other end. Good luck!

Where can i get the correct bolt? I know tractor supply will have something close, but.....