^Tread carefully as GTM has filed for bankruptcy and has hosed some customers...

https://my350z.com/forum/2009-370z/5...as-vendor.html

 

Greddy Part # Mc350-ZXR and Mc350-ZXL

Anyone who sells Greddy parts can order them for you.

Should be around $325-350 per manifold. I believe they will only sell them in pairs... at least that is what they said last time I ordered them. I have bought them 4 times for myself and others.

 

Is it better to buy new or have them welded? I guess it depends on the severity of the cracks?

 

I am no master of metallurgy but I believe the casting gets brittle from the heat cycling. If you weld it, I would be very prepared to see a new crack shortly after that precisely following the contours of the edge of the weld.

Buy new IMHO. Once they crack it spreads pretty far. The passenger side ones once removed after a while are generally cracked about 80% the way around. Ive got one here that only has about 1.25" to go before its cracked all the way around.

I will weld them up and sell them for $200 if someone wants them as spares... no warranty!

 

Punk what process and weld rod would use when you weld them .... Cast is not easy to weld I know

 

I do not weld, but 2 of my friends that work on-call for me are masters of the trade. I would have to ask them. But I believe the process might involve some preheating and special filler.

 

GTM manifolds won't work.

 

Who said they would?

 

While there are many more factors involved, crack propagation is a strong function of surface finish. Cast parts tend not to have the greatest quality finish, Combine that with rapid expansion and contraction from thermal cycling and you get cracks. Once a crack has propagated to a visible size others are probably not far behind. You can weld the first crack but another is likely not far behind. Welding the part introduces additional thermal stress and yes potentially changes the underlying material structure. Honestly the Best solution is probably buying a new manifold or possibly having something custom fabbed.

 

yea someone could make a killing custom fabbing some with a warranty with all the people having cracks.

 

bringing this thead back to life, would high temp heat coating help prolong the life of the manifold or possibley prevent it from ever cracking?

 

My first set were ceramic coated and lasted 2 years like the rest of my sets

 

The set I got were off a show car with allegedly less than 1000k miles on them. Pass side was cracked and repaired out of pocket by seller. Currently in process of installing everything but quite frankly I'm pissed, contacting greddy is a joke you can't really get parts unless you call over and over again. I ended up making my own oil feed lines since getting their fittings in the states was damn near next to impossible. Came to find out that they will be releasing a new kit for the 350 later this year with ss tubular mani's and garrett turbos as per what i was told by one of their reps.

Best advice i can give is go have some mani's custom made by a reputable shop and don't waste your money and time trying to get another set of shitty manifolds from greddy, by the time you're done with that you'll be out of the same amount of time and money to replace the already poor quality ones that cracked in the first place. That's what I'll be doing not if, but when mine crack.

As a consumer I'm pissed about the situation because its been what, 12 years? And nothing has been done about it.... i dont expect perfection but if im gonna drop thousands on something I'd hope for a lil better quality product and its a really shitty feeling knowing im putting poor quality parts on my car that will probably fail prematurely. Unfortunately i didn't do my research and its partially my fault for choosing this kit so im dealing with it. I figured greddy=quality, after seeing the manifolds i knew i screwed up considering they are the heart of this kit and they're what make the install so tedious and expensive(for those not doing it themselves).

Also for the people who say to level the manifolds so the nuts apply even pressure, save yourselves the time and just use copper washers. I was gonna try to shave them flat but realized the copper would just conform to the surface and apply even pressure. Torque what nuts you can get a socket on, starting from the middle working your way out, and the rest just do your best with a open end wrench.

/endrant

 

To be fair the rest of the kit is pretty good quality, just wanted to shed some light on this issue. From what I've been told/read some flex pipe on your test pipes or cats (if you can fit it) will take care of the cracking problem.

 

You can get a set for about $650 Shipped New online......

 

I have the Greddy kit too and after reading all the posts regarding this problem, I bought 3 Brand New sets just to be safe... Lol

 

I recently ceramic coated my current set and had flex pipes installed so maybe that will help a little. Prior to that, I had the driver's side crack on me in about a year.

 

So the coating didn't really make a difference then? You still got the same amount of time out of them as the rest of the set of manifolds?

 

Im being told that, they will still crack even giving with flex in the test pipes and solid or poly motor mounts. Nothing changes. I guess just the constant heat expansion is just going to make it crack at some point no matter what.

 

The heat expansion will Def do it and it's a lot of weight to hang off a bad quality casting. When I assembled the turbo, mani, wastegate, and downpipe adapter I couldn't believe how much it weighed. I'm still on the fence on if I want to install flex pipe on the test pipes I ordered or not. I figure since I'll be losing the stock brace that holds everything together up there it wouldn't hurt to get some flexibility back so the rest of the exhaust moves independent of the manifolds. Or might be better to weld up some steel to the tp's so I can bolt them to that brace that would normally bolt to each cat and tie the two sides together so they move with the engine and transfer movement in unison as they move side to side. That actually sounds better to me. Opinions?