th downpipe hitting heater box metal plate

[regalwe4]

i put a used th downpipe on my gn when i put it on it hits the metal plate on bottom of heater box,my other car does not do this it has alot of clearance i swapped pipes from ohter it does same thing so i know it not the pipe .i rebulit the motor last year so the motor has new motor mounts on has anybody else has this problem and what can i do to correct it i think if take the metal heat sheild off off heater box and bent it in some that willwork i think but i was wondering what i can besides this any help willbe appreciated .
thanks regalwe4 kevin

 

[Intercooler]

Don't know. I took mine off

 

[regalwe4]

tttt

 

[BoostMasterK]

2 ideas

I don't have the THDP but 2 things come to mind from my experience with the BGC... First, are you sure it's hitting the heat shield and not the seam of the floor board to the firewall? There's a lip there, about 3/4" which will probably more likely to knock the DP than the heat shield. If so, grind it down a little with a Dremel and seal it with RTV

Second, perhaps you tried this- loosen the DP/CAT clamp, have someone wedge out the DP just enough to clear the obstacles up top, then tighten the clamp while it's set. It preloads the DP a little, but works for me.

Mike [

 

[c&cgn]

Take the sheild off. Not really any other choice. That's what I had to do, as well as cut off the nob that sticks downwards that the sheild would bolt up to. Love that angle grinder

 

[TURBOV6]

Motor mounts!!!!!!!!!!!!!

 

[salvageV6]

I had the same problem with my THDP.

Motor mounts poly mount should gain you 1/8"-1/4".

Body mount cushions could also help you raise the body up some.

I removed the heat shield and cut the bottom of it off at the bend where it goes under the car, you will see it is relatively easy to cut off with a die grinder or band saw. BE CAREFUL!

You lose one mounting bolt point but there are 4 others no problem.

I also had to die grind the body seam so do that with the pipe off after noting exactly where the pipe goes past that point. Scribe the seam with a big screwdriver or something then pull the pipe and grind away.

Just my .02 on any 3" downpipe.

 

[86gn]

Originally posted by TurboV6
Motor mounts!!!!!!!!!!!!!

Had same problem it was the pass side motor mount,could not tell till i took it off it was bad.

 

[regalwe4]

thanks for info guys i put new motor mounts on new motor a year ago ive only raced the car once that was last year in november. what would new motor mounts do i have never seen this problem before i own three 87 cars and one 86 car ive havent seen this problem on my other car that got a th down pipe .is there any other way to fix problem if not motor mounts .besides grinding on the body or modifing the heat shield i check tomorrow to see if hitting the lip on body if its hitting there can i just bent it up .any more help willbe appreciated .
thanks regalwe4 kevin

 

[salvageV6]

That body seam is VERY tough. Two pieces of floor pan joined together. Had to die grind mine and it wasn't fun.

The heat shield mod. isn't too hard and doesn't look bad.

As for car differences just check the body cushions since you seem to have the motor mount issues squared away.

Just my .02.

 

[TurboDave]

I installed the new HR Pars N Stuff motor mounts and my THDP also "touches" the heater heat shield. Since the motor doesn't move around any more, I can't really say that it "hits" it, it just "touches" it. Not seeing any noise on the knock detector so it's not causing any heartburn.

As for the body seam, I just took a good short handled 5# hammer to mine and massaged the one side that was interfering way back with the original install. Didn't take much at all.

I kinda like the way things are fitting now because the down pipe is high enough, it's now where near the upper control arm bushing and won't be causing it any distress.

I would guess the reason my THDP only "touches" that heat shield instead of "hitting" it, is maybe because I also have all new upper and lower graphite body bushings, front to back.

 

[regalwe4]

thanks for info guys anybody else have anymore ideas great info guys illtry to fix it this week and let u know how i did it .anymore info will be appreciated.
thanks regalwe4 kevin

 

[U1ARUNIT]

Remove the shield. I don't miss mine at all and the PS valve cover is easier to remove as well. BONUS!

 

[kevans]

BODY BUSHINGS!

If you put on new motor mounts without putting on new body bushings you've lifted the motor up but not the body. We've had a 3.5" THDP fit after new body bushings and motor mounts were installed with lots of room to clear. 3" will hit all sorts of things with worn body bushings or motor mounts. I almost GUARANTEE this will fix the problem.

Kev