New Downpipe Clearance?

[xjh3]

Spent most of the day yesterdey installing my Dynomax Blackjack header and 99+ intake manifold. Well, when putting in the new downpipe that came with the header I tried my best to keep it out of the way of the axle. After I got it in I was going to my friend's house through an orchard and hit some bumps and heard something hit. I just went and looked today in the daylight and there is now a small dent in the downpipe. WTF. I don't offroad a whole lot, but I don't want to worry about going over bumps and hitting my downpipe all the time.

Also, I am running about 2.5" of lift. '97 AW4 4.0.

Any advice? Should I call Dynomax and b*tch?

[camarors8992]

Did you compensate your bump stops for the additional 2.5" of lift ?

[xjh3]

No, but if I did then wouldn't it bottom out everytime I hit bumps like that? These weren't overly large bumps.

[camarors8992]

Do you have any pictures to show us ? Is there any way the bend on the down pipe could be tighter and hug the jeep a little more ?

[dizzymac]

Are you sure its not the same 'dent" that comes with an OEM downpipe?

[i_carumba]

A photo or two would be good as I am about to do a similar mod
to our 97 (99 intake, Pacesetter header)

Also, did you notice any performance improvments with
the header/intake combo?

[xjh3]

I will get some pics up tomorrow for you hopefully.


Are you sure its not the same 'dent" that comes with an OEM downpipe?


Yeah, it's a completely different setup. It has a dual collector that comes into one, very different from stock.


Also, did you notice any performance improvments with the header/intake combo?


Some. Midrange acceleration seemed to be much easier and I noticed in overdrive (Auto) it doesn't downshift as much on hills or to accelerate. I damaged my cat putting in the downpipe so I am **TEMPORARILY** running a gutted cat and I think the loss in backpressure is somewhat hindering the low end performance.

[xjh3]

Here are some pics as promised:

http://i159.photobucket.com/albums/t124/hhh87/Jeep%20Tech%20Stuff/Jeepdownpipe004.jpg

http://i159.photobucket.com/albums/t124/hhh87/Jeep%20Tech%20Stuff/Jeepdownpipe003.jpg

You can see the dent in the downtube in this one.
http://i159.photobucket.com/albums/t124/hhh87/Jeep%20Tech%20Stuff/Jeepdownpipe002.jpg

http://i159.photobucket.com/albums/t124/hhh87/Jeep%20Tech%20Stuff/Jeepdownpipe001.jpg

In the instructions that came with the header, it said something about loosening the motor mounts and moving the engine to one side for maximum clearance. How the hell do I move the whole engine? Don't the motor mounts have a fixed location to hold the engine?

Once again, thanks in advance.

[Flash]

In the instructions that came with the header, it said something about loosening the motor mounts and moving the engine to one side for maximum clearance. How the hell do I move the whole engine? Don't the motor mounts have a fixed location to hold the engine?

Once again, thanks in advance.[/quote]
-------------------------------------------------------------------------------------------------------------------

I thing i would start with stronger upper and lower control arms.....or at leased new bushing in them to help control the pinion for raising enough to get to the ext................Were the eng mounts to the chassis, you could shift it over to the passenger side a little bit but not enough to clear the
clearance, that that dent did.

Probably the best thing would be to have a custom bent pipe built for an ext shop.

What about the "bump stops"? did you add a longer one with you lift kit?

If not, it could be causing your problems.

Flash.

[xjh3]

I have stock control arms but they have new poly bushings in them. But I think that the driveshaft is hitting it in the way up.

Also, it doesn't happen often but when I hit larger bumps in the road is when I think it hits. It seems to me like my bumpstops shouldn't be bottoming me out that easily, but I don't know for sure.

[Flash]

I have stock control arms but they have new poly bushings in them. But I think that the driveshaft is hitting it in the way up.

Also, it doesn't happen often but when I hit larger bumps in the road is when I think it hits. It seems to me like my bumpstops shouldn't be bottoming me out that easily, but I don't know for sure.


Take a floor jack and an put it under the drivers side of the axle, as close as you can to the tire.
Jack it up and watch what happens to the clearance between the drive line and the ext. You will not be able to put as much force on it as the road can..... but, you will get the idea of a longer bump stop helping with the problem.

Like i said before, your best bet is to get some one to bend you some pipe, tighter around, so that it will clear!

Flash.

[DrMoab]

Check to make sure your motor mounts are good.

I had this problem with a Borla header. Tried everything to make it stop then realized that the motor mounts were bad. It would actually twist it into the driveshaft.

[Harlee&Tahoe]

Have you tried it in 4wd yet? If you turn it shy of lock to lock it may get worse, but self custom clearancing before warranty runs out= Priceless

Could having a bad transmission mount cause this as well?
I'm having the same issue with my Pacesetter headers also.
New motor mounts, new track arm (Kevin's T.B. Conv. with 80d bushinngs)

Pacesetter ended up sending me a new part, re-designed, secondarys are longer and collector is after the bend under the trans..

[Flash]

Check to make sure your motor mounts are good.

I had this problem with a Borla header. Tried everything to make it stop then realized that the motor mounts were bad. It would actually twist it into the driveshaft.


Hmmm, so thats how that dent go on my nice "new' (used) header i got form ya:gee: :D .


Flash.

[Crawler]

Spent most of the day yesterdey installing my Dynomax Blackjack header and 99+ intake manifold. Well, when putting in the new downpipe that came with the header I tried my best to keep it out of the way of the axle. After I got it in I was going to my friend's house through an orchard and hit some bumps and heard something hit. I just went and looked today in the daylight and there is now a small dent in the downpipe. WTF. I don't offroad a whole lot, but I don't want to worry about going over bumps and hitting my downpipe all the time.

Also, I am running about 2.5" of lift. '97 AW4 4.0.

Any advice? Should I call Dynomax and b*tch?


Did you modify your track bar with your lift by drilling a new mounting hole or do you have an adjustible one? You can surely run into this kind of problem with 2"-4" of lift, a larger diameter downpipe and an adjusted or modified track bar. Just another possibility.

[xjh3]

I have an adjustable trackbar keeping my axle centered.

I will also check my motor mounts. I am thinking about calling Dynomax to see what they have to say. If I don't get anywhere with that, how much am I looking at for a custom bent pipe? Where would anyone recommend having a new pipe bent up? It has the dual primaries, I don't if that will be an issue.

[Crawler]

I have an adjustable trackbar keeping my axle centered.

I will also check my motor mounts. I am thinking about calling Dynomax to see what they have to say. If I don't get anywhere with that, how much am I looking at for a custom bent pipe? Where would anyone recommend having a new pipe bent up? It has the dual primaries, I don't if that will be an issue.

I've got 2.65" of lift and had to put my track bar back to the stock hole even after a custom bent 2.25" diameter pipe. Ended up having to refab the pipe, too. Absolutely no issues now under full compression. Having a pipe fabbed up at a quality exhaust shop should cost you somewhere between $60-$90 for replacing the stock one. Where you've got the two into one it might end up being more. Good luck if you decide to call Dynomax, you might need it.

[xjh3]

Stock hole? I just adjusted my trackbar. I would really like to keep my axle centered. I think it handles better and it looked goofy to me.

[xjh3]

Got some advice from a mechanic who said no to worry about the dent that is in there now, and to try shimming the motor mount on that side 1/4". Any thoughts? Anyone try this?

[Crawler]

Stock hole? I just adjusted my trackbar. I would really like to keep my axle centered. I think it handles better and it looked goofy to me.

I said "stock hole" because that was my situation.
I drilled a hole further out on my stock bar rather than replace it with an adjustible.
The amount of off-center tracking is so small (5/8") that I'd much rather live with it and be worry free on the trail.

Best of luck.

[BlueCuda]

You could put some washers under the passenger side mount which would in turn move the pipe slightly away from the driveshaft. Looks like the dent made quite a bit of room for you lol.

[FordGuy]

I just installed Currie front and rear Ford 9 inch Diffs with ARBs. I have the same problem, my exhaust is goint to get Mashed, I have built my jeep with Fox Hyd bump stops, Custom exhaust???????