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Old 04-16-2002, 11:49 PM   #1
PunksWRX
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Default Factory uppipe has flex joint??

I spoke with a very reputable Australian manufacturer this weekend and he said that the factory up-pipe has a flex joint in it under the heat shields. Has anyone confirmed this? He indicated that he felt that many people that have installed aftermarket uppipes (including myself) are likely to have problems with cracked uppipes in the future as their cars age. They have a lot of experience with the prior generation WRX and have many documented cases of uppipe failures. They are currently developing an uppipe with a flex joint in it to prevent these failures. Just wondered what you guys think of this? Has anyone had an uppipe fail yet?

Punk
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Old 04-17-2002, 12:00 AM   #2
JenisonWRX
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Al had a crack in his flage I think...

damn it al...post some pics for once
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Old 04-17-2002, 12:05 AM   #3
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I have seen one uppipe with a flex joint in it. I think it's MRT uppipe but I am not totally sure about that. I am going to go out and check my stock uppipe out RIGHT NOW!!
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Old 04-17-2002, 12:20 AM   #4
PunksWRX
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Dave,

I looked at a factory uppipe yesterday when I had the original discussion and you can't see the flex joint as it is apparently under the heat shielding covering the uppipe. And yes it is the MRT pipe that has the flex joint!

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Old 04-17-2002, 01:28 AM   #5
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So does the newer Ultimate Racing uppipe.
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Old 04-17-2002, 09:21 AM   #6
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Is there any consensus on whether this is a major feature to look for in up-pipe selection?

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Old 04-17-2002, 09:33 AM   #7
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I've got one of the new Ultimate Racing uppipes with the flex joint. It's a very nice piece no doubt, but I don't see how it won't leak at the joint itself concidering the very high exhaust gas pressure right before the turbo.

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Old 04-17-2002, 10:13 AM   #8
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Quote:
Originally posted by DanMan
I've got one of the new Ultimate Racing uppipes with the flex joint. It's a very nice piece no doubt, but I don't see how it won't leak at the joint itself concidering the very high exhaust gas pressure right before the turbo.

Dan
hrm...keep us updated on this please
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Old 04-17-2002, 11:56 AM   #9
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Obviously shiv thought it was necessary to use slip joints. If you search back you'll probably find his comments on the subject. I believe that he said that the up-pipe is a load bearing member and that the slip joints on the flanges should greatly improve the longevity of the pipe, but don't quote me on that.
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Old 04-17-2002, 03:51 PM   #10
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You don't need a flex joint in your uppipe. That's silly. There's no "load" on your uppipe. If you have a nice thick stainless uppipe, it'll hold together fine.
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Old 04-17-2002, 04:09 PM   #11
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this is pointless

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Old 04-17-2002, 04:35 PM   #12
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The stock up pipe on my STI v2 had a flexi joint until I got fed up with having to weld it up when the bellows kept splitting , now got a solid pipe , the car goes much better now
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Old 04-17-2002, 07:27 PM   #13
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Well I took a look last night but the heat shielding is welded on so I don't really want to cut it off too look. From looking inside of it I don't see any bellow/bumps type of flex joint... but there might be some type of long sleeve type of flex joint?
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Old 04-17-2002, 08:10 PM   #14
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Yes, the stock Wrx up pipe has a flex joint at the bottom of the pipe. You can't see it because the pipe goes through it and ends at the other side of the joint. All the turbo models have this flex joint, the earlier cars had the flex at the top near the turbo. The need for this is because the maniflold/up pipe expand and also at a different rate. Because the turbo is fixed, you need some sort of flex to take up the expansion. Alot of aftermarket pipes use a solid peice but a very thick gauge or a generic form of stainless tubing. Thats okay for the every day use but definetly not for racing. Eventually the pipe will crack.
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Old 04-17-2002, 08:21 PM   #15
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It's time for me to step in.

The up-pipe and the turbo are BOTH mounted to the engine. When the engine moves they BOTH move. There is no need in a flex joint.

On the other hand, the downpipe does need a flex joint.
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Old 04-17-2002, 08:26 PM   #16
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Subi-fied - Can you answer me this then. Why do people emphasize the importance of a flex-joint on the after market headers (with the flex joint usually located between both banks of cylinders)? Just curious. That seems like it would support the same "everything is bolted to the engine and therefore moves together theory?"

Thanks
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Old 04-17-2002, 08:33 PM   #17
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Quote:
Originally posted by davidm_sh
Subi-fied - Can you answer me this then. Why do people emphasize the importance of a flex-joint on the after market headers (with the flex joint usually located between both banks of cylinders)? Just curious. That seems like it would support the same "everything is bolted to the engine and therefore moves together theory?"

Thanks
I'm not sure David, I haven't heard of that yet. But I can promise you that the MAIN reason the flex joints are used is to control FLEX and prevent cracking. The up-pipe doesn't need one and neither do headers. There is such thing as an " over design."
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Old 04-17-2002, 08:40 PM   #18
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Quote:
Originally posted by Subi-fied
It's time for me to step in.

The up-pipe and the turbo are BOTH mounted to the engine. When the engine moves they BOTH move. There is no need in a flex joint.

On the other hand, the downpipe does need a flex joint.

Granted, but most of the heat is generated at the top of the flange(turbo) and the bottom where the downpipe actually mounts to the main manifold. Like I said, for everyday "normal" use it may be okay not to have a flex. But for race purposes, you DO need a flex or a slip fit. That I speak from experience.
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Old 04-17-2002, 08:44 PM   #19
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Slip fit - yes, flex joint - no.
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Old 04-17-2002, 09:52 PM   #20
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Soooooo . . . getting back to my main point. How long are uppipes without either a flex joint or a slip joint gonna last? Should I worry with my Perrin uppipe?

Punk
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Old 04-17-2002, 10:18 PM   #21
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I may be wrong, but I think overall movement is not the issue here. Thermal issues between dissimilar metals and vibration are the reasons for the need of flex joints. I know this is the reason for this type of joint on aircraft.
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Old 04-17-2002, 10:24 PM   #22
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Paul - I think only time will tell. I am sure we will start too here about the problems here if they start happening. The problem is is that the cars are relativly new to the US and most people on this and other boards that have installed one probably have only had it on for 8 months or less.

Just don't worry about it until it breaks ... if it breaks I guess . What else can you really do. If it's not broken don't fix it. I mean the worst that would happen is you would get an exhaust leak from it cracking or whatever and then you can buy a new "flex joint" one [heh]. Not much help I know but really what alternative do we have?
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Old 04-17-2002, 10:29 PM   #23
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You are absolutely right Dave. I shouldn't lose any sleep over this and just start saving the bucks for an MRT uppipe! We shall see. I just wonder what kind of warranties uppipe manufacturers are implying with their products? MRT says it's only a matter of time before we start seeing problems.

Uncle Scotty you are right on the money.

Paul
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Old 04-17-2002, 10:34 PM   #24
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Of the 1000 uppipes sold to i-club members only 1 has failed that has been posted and that was AL's who said his was modified. Some uppipes are of very poor quality with 5/16" mild steel flanges welded to 304 stainless and NONE have failed yet.

Shiv's uppipe using 321 stainless is suitable for temp's of 1800deg(304 is not) and it is self annealing.

Do yourselves a favour and worry over things that do happen and not the things that might happen.

If you want info on stainless and other materials.
http://www.matweb.com/searchindex.htm
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Old 04-18-2002, 07:49 AM   #25
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Quote:
Originally posted by PunksWRX
Soooooo . . . getting back to my main point. How long are uppipes without either a flex joint or a slip joint gonna last? Should I worry with my Perrin uppipe?

Punk
Dude, it's fine. Mabe if you drove under boost for ten minutes straight when your engine was freezing cold 100 times in a row it would crack. Under normal driving conditions it's fine. Just don't haul ass in your car until it enters the normal operating temperature range. Give it time to warm up, so the expansion under heat isn't a problem. Actually the same thing is true about your cylinder sleeves. If you haul ass when it's cold the sleeves could expand too fast and could do damage to a cold block. But you don't really have to worry about that either.
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