Intermediate pipe / Backbox installation guide
04-22-2012, 05:53 PM
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Intermediate pipe / Backbox installation guide
I have recently completed fitting a new intermediate pipe / back box / tail pipe arrangement to my GTA. Hit a few issues along the way and looked around forums to find advice (not very much on this topic out there!) so thought I'd share the details, and the easiest method to complete installation.
I hope this comes in handy to someone, perhaps an administrator will make this guide a sticky important one at the top of the page.
If you have access to pits / hydraulic ramps then you probably won't need any of this, this is for the home mechanic with a jack and stands!
Terminology: RHS is right hand side of the car as you look at the car from the rear, and likewise LHS is left hand side.
Additional bits required apart from tools and the new exhaust:
- Rust remover / penetrating oil - exhaust fumes freeze rusted parts.
- Rotating / bending joint for socket set (useful for bolting up the new pipe to the cat)
- Anti seize paste - apply to the intermediate pipe to cat bolts before bolting up.
1. Jack up the car under the bell housing of the rear axle and place jack stands under the hard points just in front (towards front of car) of the rear control arm pivot bolts. Do not support the car on the axle as you will need to lower this.
2. Once the car is secure on stands, lower the jack so that the axle drops to it's full extension on springs. Leave the jack where it is once lowered as you will need to support the axle later.
3. Unbolt / unclamp the backbox from the intermediate pipe. This will either be bolts, or a friction fit clamp. If the parts have been welded together you will need to cut through the exhaust with a hacksaw / dremel. They will only be welded if a garage has decided the best fix for a hole is welding rather than a new exhaust.
4. Unbolt the exhaust hangers supporting the backbox and tail pipes. Take care when doing this so the backbox and tailpipes don't land on you! Remove the backbox and tailpipes if they haven't already fallen off. If you require these later set them aside.
5. Remove both heat shields. These are two sheets of metal, one covering the back centre of the car and the other up in the wheel arch where the intermediate pipe roller coaster is (the roller coaster is the bendy bit that loops over the axle and track bar brace
). There are several small 9/32" bolts holding the heat shields up, make sure you get all of them before attempting removal.
7. Remove the exhaust hanger clamp holding the intermediate pipe up. The exhaust clamp is located towards the rear end of the intermediate pipe on the RHS of the car. Don't bother trying to fiddle the intermediate pipe out without removing the clamp, it doesn't quite slide back far enough!
6a. Remove the 3 bolts holding the track bar brace to the body of the car (LHS of the car). Remove the nut and bolt holding the other end of the track bar brace (RHS of the car). This was a very stiff rusted nut and bolt that needed some penetrating oil to help budge it! I think it was frozen from exhaust gasses too as I had a hole in the exhaust right near it. The track bar brace is the top bar of the two metal bars going horizontally across the rear of the car behind the axle.
6b. Remove the pivot bolt on the RHS of the track bar. It is advisable at this stage to ensure that your jack is under the bell house of rear axle and lightly supporting it. This aids re-installation of the track bar by keeping the axle in the same place. The track bar is the lower of the two horizontal bars at the rear of the car. This bolt should come off easyish as it is only torqued to 58 ft lbs. There is no need to remove the bolt on the LHS as the bar can easily be rotated downwards out of the way.
7. Scrabble to the middle of the car, and loosen and remove the bolts holding the intermediate pipe to the cat. You don't need to separate the parts at this stage.
8. You should now be able to remove the intermediate pipe. Pull it away from the cat so that it hangs down on the floor, it helps if the ground is flat and smooth under the car. Now push the intermediate pipe towards the front of the car and rotate clockwise as you do it. As the axle housing is lowered and the track bar brace is removed, the pipe should push out with ease. This bit is not an exact science, so you may need to fiddle around a bit to get it out.
9. Hurray! It's removed. Well done. Now it's time for installation of the new exhaust. Slide the intermediate pipe under the car. Starting with it upside down (sounds silly but it helps), and nudge the end of the pipe over the axle. Rotate the pipe so the right angle bend that will sit over the axle is pointing towards the wheel and slide the pipe over the axle until the bend is in-line with the axle. Rotate the pipe so that now the bend points up into the cavity over the axle. Once this is done, the hard part is over!
10. Bolt up the intermediate pipe to the cat loosely at first and don't worry about the seal to much, we'l revisit this later. The reason for the initial bolt up is to steady the pipe while you bolt up the rear.
11. Re-attach the track bar bolt that you removed on the RHS. You may have to pull it to the right a little bit to line up the holes if the axle housing has moved. Torque up, 58 ft lbs for 1987 and earlier, 78 ft lbs for 1988 and later (Haynes extract). You can take the jack away once this is done if you so desire.
12. Fit the heat shields back, the one in the wheel arch first (seemed to make things easier!). You won't be able to attach two of the bolts yet as they attach to the track bar brace that you removed earlier.
13. Slide the exhaust hanger clamp onto the intermediate pipe hanger, and then bolt it to the chassis, bolting it first and then trying to slide the intermediate pipe hanger in is a pain so don't do this.
14. Most of the work is now done you'll be pleased to know. Re-attach the track bar brace, putting the RHS nut and bolt on first (helps with alignment). Then bolt the 3 bolts on the LHS. Torque up, 58 ft lbs for the nut and bolt, 34 ft lbs for the 3 bolts on the LHS. (Haynes extract). Once the track bar brace is in place you can bolt up the two remaining screws for the heat shield.
15. Now we revisit the intermediate pipe to cat bolts. Now that the rear is steady we can afford to loosen the bolts and position the exhaust correctly to get the best seal. Try pushing up slightly on both cat and exhaust to get best fitting - either with a helper or with the two parts loosely bolted. Tighten the bolts once you are happy with the seal. I'm not sure what torque is required here, I think it might be cat dependent. I went up to 50 ft lbs. The bendy socket adapter comes in handy here as the RHS bolt is a tight squeeze.
16. If your tail pipes are separate from the back box, attach these to the exhaust hanger clamps first, this is so that they are partially fixed when trying to join up the back box. If they are all part of the same assembly don't clamp up until the back box assembly is clamped to the intermediate pipe.
17. Slide the back box onto the intermediate pipe, ensuring you have slid a clamp on first. The intermediate pipe has enough strength to support the back box assembly while you busy yourself clamping up. Loosely tighten the clamp between the back box and intermediate pipe. If you had the all in one assembly, now clamp the tail pipes to the hangers.
18. (Separate back box / tail pipe assemblies only) Slide a clamp on to each of the back box outlets and mate the back box with the tail pipes. The reason for only loosely tightening the intermediate pipe now becomes clear - for the RHS tail pipe you will have to rotate the box a little so that the tail pipe fits under the overlapping intermediate pipe. Tighten clamps on all parts once you are satisfied on the position of the back box and tail pipes. I torqued mine to about 40 ft lbs, and they hold nicely when going over poorly maintained roads.
19. Lower the vehicle, start the engine and admire your handy work! Be sure to visually check each joint for emissions, to confirm you have a good seal on all the parts. Interestingly the LHS tail pipe on mine flows more than the RHS one (probably down to the back box set up!).
Initially I spent hours fiddling around trying to remove the exhaust, and found that these steps were the best route with the minimum amount of effort.
Feel free to comment / ask any questions. Hopefully I can answer them for you!
I hope this comes in handy to someone, perhaps an administrator will make this guide a sticky important one at the top of the page.
If you have access to pits / hydraulic ramps then you probably won't need any of this, this is for the home mechanic with a jack and stands!
Terminology: RHS is right hand side of the car as you look at the car from the rear, and likewise LHS is left hand side.
Additional bits required apart from tools and the new exhaust:
- Rust remover / penetrating oil - exhaust fumes freeze rusted parts.
- Rotating / bending joint for socket set (useful for bolting up the new pipe to the cat)
- Anti seize paste - apply to the intermediate pipe to cat bolts before bolting up.
1. Jack up the car under the bell housing of the rear axle and place jack stands under the hard points just in front (towards front of car) of the rear control arm pivot bolts. Do not support the car on the axle as you will need to lower this.
2. Once the car is secure on stands, lower the jack so that the axle drops to it's full extension on springs. Leave the jack where it is once lowered as you will need to support the axle later.
3. Unbolt / unclamp the backbox from the intermediate pipe. This will either be bolts, or a friction fit clamp. If the parts have been welded together you will need to cut through the exhaust with a hacksaw / dremel. They will only be welded if a garage has decided the best fix for a hole is welding rather than a new exhaust.
4. Unbolt the exhaust hangers supporting the backbox and tail pipes. Take care when doing this so the backbox and tailpipes don't land on you! Remove the backbox and tailpipes if they haven't already fallen off. If you require these later set them aside.
5. Remove both heat shields. These are two sheets of metal, one covering the back centre of the car and the other up in the wheel arch where the intermediate pipe roller coaster is (the roller coaster is the bendy bit that loops over the axle and track bar brace
). There are several small 9/32" bolts holding the heat shields up, make sure you get all of them before attempting removal.7. Remove the exhaust hanger clamp holding the intermediate pipe up. The exhaust clamp is located towards the rear end of the intermediate pipe on the RHS of the car. Don't bother trying to fiddle the intermediate pipe out without removing the clamp, it doesn't quite slide back far enough!
6a. Remove the 3 bolts holding the track bar brace to the body of the car (LHS of the car). Remove the nut and bolt holding the other end of the track bar brace (RHS of the car). This was a very stiff rusted nut and bolt that needed some penetrating oil to help budge it! I think it was frozen from exhaust gasses too as I had a hole in the exhaust right near it. The track bar brace is the top bar of the two metal bars going horizontally across the rear of the car behind the axle.
6b. Remove the pivot bolt on the RHS of the track bar. It is advisable at this stage to ensure that your jack is under the bell house of rear axle and lightly supporting it. This aids re-installation of the track bar by keeping the axle in the same place. The track bar is the lower of the two horizontal bars at the rear of the car. This bolt should come off easyish as it is only torqued to 58 ft lbs. There is no need to remove the bolt on the LHS as the bar can easily be rotated downwards out of the way.
7. Scrabble to the middle of the car, and loosen and remove the bolts holding the intermediate pipe to the cat. You don't need to separate the parts at this stage.
8. You should now be able to remove the intermediate pipe. Pull it away from the cat so that it hangs down on the floor, it helps if the ground is flat and smooth under the car. Now push the intermediate pipe towards the front of the car and rotate clockwise as you do it. As the axle housing is lowered and the track bar brace is removed, the pipe should push out with ease. This bit is not an exact science, so you may need to fiddle around a bit to get it out.
9. Hurray! It's removed. Well done. Now it's time for installation of the new exhaust. Slide the intermediate pipe under the car. Starting with it upside down (sounds silly but it helps), and nudge the end of the pipe over the axle. Rotate the pipe so the right angle bend that will sit over the axle is pointing towards the wheel and slide the pipe over the axle until the bend is in-line with the axle. Rotate the pipe so that now the bend points up into the cavity over the axle. Once this is done, the hard part is over!
10. Bolt up the intermediate pipe to the cat loosely at first and don't worry about the seal to much, we'l revisit this later. The reason for the initial bolt up is to steady the pipe while you bolt up the rear.
11. Re-attach the track bar bolt that you removed on the RHS. You may have to pull it to the right a little bit to line up the holes if the axle housing has moved. Torque up, 58 ft lbs for 1987 and earlier, 78 ft lbs for 1988 and later (Haynes extract). You can take the jack away once this is done if you so desire.
12. Fit the heat shields back, the one in the wheel arch first (seemed to make things easier!). You won't be able to attach two of the bolts yet as they attach to the track bar brace that you removed earlier.
13. Slide the exhaust hanger clamp onto the intermediate pipe hanger, and then bolt it to the chassis, bolting it first and then trying to slide the intermediate pipe hanger in is a pain so don't do this.
14. Most of the work is now done you'll be pleased to know. Re-attach the track bar brace, putting the RHS nut and bolt on first (helps with alignment). Then bolt the 3 bolts on the LHS. Torque up, 58 ft lbs for the nut and bolt, 34 ft lbs for the 3 bolts on the LHS. (Haynes extract). Once the track bar brace is in place you can bolt up the two remaining screws for the heat shield.
15. Now we revisit the intermediate pipe to cat bolts. Now that the rear is steady we can afford to loosen the bolts and position the exhaust correctly to get the best seal. Try pushing up slightly on both cat and exhaust to get best fitting - either with a helper or with the two parts loosely bolted. Tighten the bolts once you are happy with the seal. I'm not sure what torque is required here, I think it might be cat dependent. I went up to 50 ft lbs. The bendy socket adapter comes in handy here as the RHS bolt is a tight squeeze.
16. If your tail pipes are separate from the back box, attach these to the exhaust hanger clamps first, this is so that they are partially fixed when trying to join up the back box. If they are all part of the same assembly don't clamp up until the back box assembly is clamped to the intermediate pipe.
17. Slide the back box onto the intermediate pipe, ensuring you have slid a clamp on first. The intermediate pipe has enough strength to support the back box assembly while you busy yourself clamping up. Loosely tighten the clamp between the back box and intermediate pipe. If you had the all in one assembly, now clamp the tail pipes to the hangers.
18. (Separate back box / tail pipe assemblies only) Slide a clamp on to each of the back box outlets and mate the back box with the tail pipes. The reason for only loosely tightening the intermediate pipe now becomes clear - for the RHS tail pipe you will have to rotate the box a little so that the tail pipe fits under the overlapping intermediate pipe. Tighten clamps on all parts once you are satisfied on the position of the back box and tail pipes. I torqued mine to about 40 ft lbs, and they hold nicely when going over poorly maintained roads.
19. Lower the vehicle, start the engine and admire your handy work! Be sure to visually check each joint for emissions, to confirm you have a good seal on all the parts. Interestingly the LHS tail pipe on mine flows more than the RHS one (probably down to the back box set up!).
Initially I spent hours fiddling around trying to remove the exhaust, and found that these steps were the best route with the minimum amount of effort.
Feel free to comment / ask any questions. Hopefully I can answer them for you!
08-04-2017, 07:34 PM
#2
Supreme Member
Re: Intermediate pipe / Backbox installation guide
Excellent write up here. That long intermediate pipe will go right in with these directions. Took a long search to find it though. Should be a sticky. Might change a few terms, back box is the muffler. Tighten the track bar/panhard bar bolts with the weight on the tires in the normal position. And a couple of those bolts will only go in one way, and not the easy way.
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