Rear Sub Frame Upgrade

[lilmartian09]

So here is what happened. My sub frame has a small crack. Not fully broke yet. I need some suggestions as to what I should do. If I get another frame it will crack. I have over 300whp and I dont want it to snap again. Is there any way to fix this or send to someone who can upgrade and repair. All inputs please. Thank you

 

[hvyman]

Yes. Need to remove weld and brace.

If you search shaeff has detailed info in his build thread. And there are other threads with links to the page in his build thread. Think it's like page 32 or something but idk for sure.

 

[lilmartian09]

I will check out. Thank you

 

[lilmartian09]

http://www.supramania.com/forums/sh...te-7-12-09-White-car-stripped-for-paint/page6

It was on pg 6-9. Seems going 89+ subframe is better. Just need to reinforce corners. Thanks a lot. Hope this helps others.

 

[DeMoN2318]

You can brace the Pre-89 sub frame. (first time welding...so go easy on me)

 

[hvyman]

Its also good to entirely strip the whole sub frame and then go over all the stock welds and what no. ive see seperation before on both front and rear subframe where 2 pieces of metal meet together.

and then after you can por 15 or powder coat it for durability.

 

[black89t]

ive broken a couple subframes now and they're always broken in the same place by where the pinion bolts up. ive seen some people that have almost broken theirs in half but i think thats from them driving on it forever with the pinion bolt area cracked. now on my 3rd subframe i took the time to brace it and its held up to my abuse nicely. and im not easy on my car at all :evil2: heres pics for you too see.


this is the weak point with them in my opinion. that large hole there seems to promote cracking


here you can see i made a plate that cover that hole and braces where it always cracks. i drilled a small hole in it after for it to drain too.


the welds are this side are sorta shit but they work lol

 

[hvyman]

That whole front area is a major weak point. ive also see the rear diff mounts crack loose as well.

having an old rusty frame doesnt help things either.

 

[DeMoN2318]

Its also good to entirely strip the whole sub frame and then go over all the stock welds and what no. ive see seperation before on both front and rear subframe where 2 pieces of metal meet together.

and then after you can por 15 or powder coat it for durability.

yep, had mine powdercoated

 

[slowma70]

Do you guys have an idea of how much a shop would charge to reinforce my subframe if i bring it to them?

 

[hvyman]

Prolly couple hundred. Might depend on how much prep they have to do too.

 

[slowma70]

Thanks^ sounds fair.. About how much hp does it take to crack the subframe?

 

[DeMoN2318]

Thanks^ sounds fair.. About how much hp does it take to crack the subframe?

<300

Mine was cracked and I am only basic BPU...and its an AZ car...so no rust

 

[hvyman]

Mine was cracked with less than 300.

 

[Poodles]

Seems to be that the diff comes loose and then causes extra stress on the subframe causing the cracks. Considering I've seen it on stock cars and not seen it on heavily modified cars as well.

 

[yhatzee89]

Would you guys recommend factory or poly subframe bushes when redoing the subframe? And spacers or no? Or are they the same thing? Overall I'm just really confused

 

[Poodles]

Would you guys recommend factory or poly subframe bushes when redoing the subframe? And spacers or no? Or are they the same thing? Overall I'm just really confused

Spacers effectively hard mount the subframe to the body. Bushes will just stiffen it up without hard mounting which could transfer noise and vibration into the body.