so the shop that i took my car to told me my rear sub-frame was broken, so i got my car in the air and inspected it and sure enough it's broken near the bolts near my rear-diff....

i always did feel a clunking and wondered wtf was going on, so i wedged a piece of hard rubber between the crack for the mean time but i was wondering what damage i could sustain driving it like this for a little longer....

i located a replacement for $170 canadian, and so far thats what i'm going to have to go with....

any help and info would be greatly appreciated....

-Anthony

 

further more, is the rear sub-frame the same with the S4's and S5's?... and from NA to turbo?...

 

Yup

 

ive had this happen 2x! the bracket that the front of the rear diff mount bolts on to broke, replaced it first time then uber welded it back on the second time. well id say the posible damage could be the driveline break, as the second time i had this happen the driveline broke at the same time!, as when the front mount is broken, the diff will move up and hit the bottom of hte car!, this changes the driveline angle suddenly and it can break easyer

 

Define broken subframe.

A common clunk would be the front diff mount rubber snapping apart.
If it was bad enough the driveshafts ujoints could get ruined.

Now is the little tab of metal between the front diff mount broken?

of a major part of the frame itself?

If it's just the part where the front diff bolts to the frame then weld in a new piece of metal.
That's what I did. I cut out a small piece and drilled out the locations for the bolts.

Good as new.

 

it's where it bolts to the rear diff....

it clunks when i get on the gas and off the gas, i dont see the driveline hitting anything anywhere other then the clunking, and i rather have it run properly....

$350 for it installed, canadian too....

i'll sell my old one after it's fixed....

 

i'm in the process of swapping the one on my car,
seems the cars built in 88 and later have a stronger sub-frame,
earlier ones are the weakest.
doesn't matter if it is from a N/A or turbo car, same brace!

with everything apart, it would be a good time to install the energy suspension poly bushings.

could also add in a pinion snubber just above it.
it's a "just incase" type item,
i stopped driving mine about an hour after it happened,
don't want to screw the u-joints up since then you have to replace the driveshaft.

 

holy crap dude, are you serious?...

how am i suposed to tell the difference from an 1988-1991 sub frame?...

PM please!...

 

any FC made in 88 or later according to the sticker in the door jamb will tell you.

just look for an S5 rear crossmember when you go to the wrecking yards.

 

the problem is, i'm picking one up from a shop on friday....

anything particular that i can look at to distinguish the difference?...

and how much "stronger" is the newer one?...

 

well, best bet is to have someone weld some extra bracing in.

i welded (added extra to strengthen it up) my S5 cross member,
so i can't show you a difference between the S4 & S5 rear crossmembers.

just get the shop installing it to add some extra welds to the welds already there and that should work.

you could always add in a pinion snubber, it's very easy to do.
if you take out the storage bins, there is a dimple right in the center of the driveshaft hump,
it is the EXACT spot to drill, just get yourself a energy suspension pinion snubber.
then you have an extra safety net should you have the mount break again.

PM me an e-mail address,
i can send some pics of the pinion snubber install (if you want them that is...)

 

You're not alone.

 

If this happened to me, I would make sure it wouldn't happen again by fabbing a new part out of 1/4" steel. Just something to consider...

 

so basically the weaker subframe of the 2 will look to have less material?...

where as the S5 or 1988 and newer will have a different cross member?...

just woke up but this is what to look for?...

 

In the picture from SureShot, that is not where mine broke. I ripped that entire support out of the subframe. Ended up buying an entire new subframe from Mazda. This was around 94'. I don't remember the cost, but it is still holding and I did not reinforce the new one.

 

i'll check into that tommorow, thanx InGroundEffect!...

the problem is, it was broken for months before i noticed, but i dont think thats where mine's broken either, and i raced, burned out, and BS'ed around, yet thankfully havent broken anything else....

i hate not knowing when somethings wrong with my car....

 

That's what I did. Too bad it was on the one I sold.

Now I'm back at square one with this car

 

no, the cross members look exactly the same,
i believe it is how well the welds were done at the factory for the mount (as that seems to be the only thing that breaks so often from the cross member)
and therefore, when looking at the 2 different (S4 & S5) crossmembers, i doubt you would be able to see a difference.

i'm sure the dealer would only sell the S5 replacement one since it is the stronger of the 2,
at what cost.... i don't know.

 

$780cdn before TAX....

 

Glad I found this post as I'm replacing my front diff mount this week.

My question is where is the best place to support it while your taking the subframe out? Right now I have it up on the rear control arms, if I try to support it on any of the body lift points stuff starts to bend.

I was just going to drop the thing, put the mount in, make a bump stop in case it gave me another problem and put it back in but now I'm going to drop the whole subframe and add a few welds and maybe a gusset or two depending on the design, I can't get a good look at it yet. Right now I have it in the air and am doing my customary Purple Power cleaning before I unbolt anything, attempting to get my computer to download the sections of the fac manual I'll need.

I'll be ordering the mount tomarrow and will hopefully have the whole car back together next weekend, what are some other tips I should know?

Thanks,
K6