Anyone Ever Shear Subframe Bolts??

[grandprixgtp_91]

I recently turned my boost to 10 PSI and installed my Methanol Injection kit today and was out test driving the car, man it was hauling alot of ass.

Anyways , i stopped, went to launch the car and i did a quick shift to 2nd gear at about 30mph and i heard a loud bang, the car ripped off to the side of the road, and my steering wheel was jacked about 90*

Good thing i was infront of my house

I pulled in and looked under the car and it had sheared 2 subframe bolts in half, nice clean break, and those bolts were brand new GM ones from last summer, they were still black and had no rust on them at all. so i know it wasnt from them being pitted out or anything. and yes they were tight too.

Just wondering if anyone has had this problem before, and if anyone knows of stronger bolts i could use for problems like this. i was thinking about going SS


Thanks

Jake

[IsaacHayes]

!!!!!!!!!????!!!! Did you OVER tighten them and they snapped from shear tension and then stress?

[grandprixgtp_91]

lol nah they wernt over tightened.

This is the first ive heard of this happening,

lol im not sure if its to much power with to "sticky" of tires ( BFG Gforce KDW, p255/40zr17) because as soon as i crammed it into 2nd and punched it they sure let go lol.

thats the problem with these tires, they just wont spin on the street ( they spin on the track tho lol

Jake

[robertisaar]

well, we all know that sticky tires+power+FWD=Massive tranny death... so i don't think the power was the issue, i imagine your tranny would have let go first if that was why.

[grandprixgtp_91]

Well it is a manual transmission, and with the gear reduction, the torque output would be crazy high.

So i honestly cant see what else would have caused it.

Jake

[IsaacHayes]

I'd see the axles breaking or something else before the subframe, but I don't know how a W body looks under there. Are your control arm bushings made of solid steel? LOL no give?

[grandprixgtp_91]

Lol no its all stock in that sense.

i mean its not the subframe itself that broke, just both bolts on the passenger side sheared off.

but now that i think of it, man i hope it didnt bend the subframe, at least i let off as soon as i heard the bang.

Jake

[jmgtp]

That is a pretty terrifying scenario! did the steering pull apart when the subframe fell? I guess you can be glad it was only going into 2nd and not something like 4th where you would have been going much faster. I think the subframe itself should be ok.

I now live in fear. My subframe bushings are shot and I've reused the torque to yeild bolts. Good thing I probably make less than half the power your motor!

Sounds like you recently replaced your subframe bolts/bushings, may I ask how much and where you got them?

[grandprixgtp_91]

No, the steering did not fall apart, lol which is a good thing, at least i was in front of my house, and i was able to hobble into my driveway with it .

I bought the parts at the dealership when i worked there , i cannot remember pricing because i had boughten so many things at the time tfor the turbo all prices are blank right now, i do remeber that they werent to cheap though.

Jake

[IsaacHayes]

Maybe the bolts were too brittle when hardened? bad batch? Maybe not tight enough and so there was less clamping force and allowed side pressure from the subframe to shear them off?

[grandprixgtp_91]

that is possible, since i did buy them all at once, lol its still wierd though.

im replacing everything now, all new bushings, new bolts, and nuts, hopefully this wont happen again.

Jake

[IsaacHayes]

Better bring spare bolts if you go to the drag strip!!!

[grandprixgtp_91]

Lol ya i was gonna go to the stip next weekend too, im glad this happend now.

Jake

[Dave96z34]

Maybe the bolts were too brittle when hardened? bad batch? Maybe not tight enough and so there was less clamping force and allowed side pressure from the subframe to shear them off?

I agree its a bad batch. If you had the money you could have them sent out to be tested. Iv seen bad bad bad wbody crashed cars and only seen a 2 break clean. What bolts broke front or rear?

[grandprixgtp_91]

Well lets hope they were a bad batch, because i dont ever want that to happen again.

And it was both passenger side bolts that broke.

I ordered all new bushings and bolts again today. maybe the new bushings will not let the subframe move around so much, the old bushings were getting pretty soft.

Jake