Control/thrust arm replacement (front + rear)?

Hi all, I have a loud clunk from my front suspension when going over bumps at low speed. Dealership confirmed this as being worn thrust arms on the RH front and LH rear. Ordered genuine replacements and they arrived this week. I have the factory manual but its fairly vauge around front suspension (for me anyway). Few questions, the steps i'm planning to take for the front are: 1. Jack up car 2. Lower car onto front jack stand 3. Remove RH front wheel (will use air wrench) 4. Remove wheel well linings + under body linings? 5. Spray bolt in red with WD-40 and undo 6. Spray bolt on the other end and undo 7. Undo/loosen boomerang bracket to allow control arm out (saw a youtube video of a recommendation of this - below) shown below highlighted in green 8. Install new control arm to body/suspension sub frame (torque value?) 9. Install arm to coffin arm (torque value?) 10. Tighten boomerang bracket (torque values?) Is the method/steps correct? Also is the procedure the same for the rear? It appears the rear arm to body uses a bolt and a nut whereas the front is only a bolt? Part being replaced: Torque values (confirmed) Pelican parts diagram (what is the tightning torque of the bolt in red?): Front parts diagram: Rear parts diagram: Youtube video of replacement on 986 (guy doesn't use a torque wrench and at one point uses his foot to push on the wrench! I don't know if I trust him!) You Tube Any help would be appreciated, I guess I could just have a go but I don't want to have my car immobile in the garage! Thought i'd also compile all the data/diagrams i've collected for this job in one thread too. Thanks

Did you read this? http://www.pelicanparts.com/techarti...n_Overhaul.htm

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Thanks, I did but it's a bit vague on the replacement of this specific arm and the torque values.

You can replace this arm in the front by jacking the car, removing the wheel, and removing only the two bolts on the arm, most likely without loosening the boomerang plate. Although now that I think about it, I may have done front sway bar bushings at the same time. I would try doing just the two bolts first. Torque values

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Thanks, was your reply missing the torque values if you had them? I don't mind loosening the boomerang plate but have struggled to find the values of all the bolts.

The bolt at the boomering end: 88 ft/lb The nut/bolt at the center of the lower control arm: 118 ft/lb I have a 986 Boxster so my corresponding arm in the back is different and takes 118 ft/lb on both ends - I don't have the manual for the 996 so I don't know the values for the back, but if it is the same arm in back as in front I am guessing they are the same.

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Excellent, thanks! Do you have the values of the other bolts on the boomerang? Youre correct, on the 996 the front and rear are the same part. 986 rear is 986 specific. ​​​​​

Sorry my reply got cut off on my phone... I only have the two sway bar bolt values on the boomerang, and I can't find them now, and I never did find the other end bolt on the boomerang. I think I have them in a PDF at work that I can check Monday, but I bet you can slide that end in and out without loosening the boomerang.

And my work is just 1 mile up the road, I can slide up there and check tomorrow if you have to loosen the boomerang to get the arm.out.

Thanks, I'll give it a go on the weekend and report back! I'll be happy if I can get at least the front done for now. The rear looks like access to the bolt to the body could be limited. Cheers!

Front: You'll want to loosen the boomerang but the diagonals can stay. 118ft/lbs on both ends of thrust arm. Rear thrust arm: 133ft/lbs to sub frame and 118ft/lbs to lower control arm. If I remember correctly, the bolt to the subframe can be challenging to get to. So allow a little extra time for it and be prepared to remove other pieces if required.

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Thanks slakker, the rear does look a little challenging especially because it's not just a bolt to the subframe it's a nut as well. Do you know the torque spec for the other bolts on the boomerang?

It's 48 ft lbs for the 2 bolts covering the sway bar 74 ft lbs for the front bolt.

My front torque specs came from.the 986 manual, that might be one of the differences up front between the 986 and 996. Slakker has a 996, I would use his torque values.

Thanks everyone

I had a rattle in my 2003 C4S that was caused by the front lower control arms. It was present at least as early as 20,000 miles on the odometer. The car drove fine but the noise increasing was an irritation on the city streets with cracks and potholes. It was on both sides. The curious thing was that the rattle didn’t start until the car had been driven 10 miles or so and it went away when even light braking was applied. I replaced the control arms that you are working on and it has been fine so far for 5000 miles. Looking at the original parts, I could see nothing that was wrong to the eye. I also could not see any movement when they were on the car. I looked on the 996 and Boxter Rennlist posts and did not find any people commenting about this problem. I guess this is because people just accept the noise or their streets are smoother than ours. I have to believe this is a common problem. After installing the arms, I had the car realigned. This might have been unnecessary since the before and after numbers were ok.

I had the dealership diagnose the sound which was happening at low speed, kind of a metallic clunk noise. Either was I hope it's that! ​​​​​​ Ive recently swapped back to 5 spoke 996 rims from 997 ones and the tyres have a little life left in them so planning to wear these out then get brand new PS2s and a full dealership alignment. Dealership told me it takes 2 hours to do a proper alignment but whether there's any truth to that I'm not too sure but I've trusted them on everything else so ill get it done eventually.

My 4 wheel alignment cost $325 (US) so two hours seems right. How much are a set of PS2s in Melbourne? They are $1425 plus shipping and mounting in the US from Tire Rack. That is for 225/40-18 and 295/30-18.

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Almost the same price, I have seen the front for $250 each and the rear for $500 each. ​​​​ ​​​​​​

Okay gentlemen, thanks for all your help! ​​​​​​ Front went successfully, ran out of time for the rear will have to do it next weekend. I can confirm if anyone experiences a metallic clunk it's this arm. When I removed it I could freely move the ball joint side to side... Eeep!

The rears were a complete pain in the $%. Fronts were easy. For the rears, best of luck getting the nut threaded on the top of the bolt. I had to by a long set of pliers to hold it in place and fold back the wheel liner. Hope that saves you time.

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Thanks going to give the rear a shot on Sunday. I did plan to remove the lining

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For Thrust Arms: Definitely remove the lining if you can. The space is very, very small so putting in a little more time before starting will save you in the long run. To start: Getting the nut off (18mm?), the bolt, the control arm bolt/nut and removing the arm wasn't difficult. It gave me false confidence this was an easy job like the fronts. From there, you'll need to find the right angle to push the new arm in (towards the engine) to accept the bolt while aligning it with the control arm. Thats tough. Then comes getting the nut to thread. I was able to get a single finger on the top of the nut and it took a number of tries to get it to thread, 30-40m if I remember. Once you get the nut threaded, I used an impact hand drill with a socket on the bolt to get it going somewhat. This becomes a two arm job now. In one hand I had a massive torque wrench on the bottom bolt. Simultaneously in my other hand I used a very long wrench on the top nut with the wrench arm following the thrust arm. The nut when tightened recesses so thats when the pliers came into play because the top wrench will not fit. You'll need to get a locking set of pliers to clamp on the top of the nut at a downward angle. Hard to explain but you'll see what I mean when you get the liner pushed back or removed. I believe someone already put the torque specs but its well over 100lbs if I remember. Fronts took 45 minutes. Rears took me 3 hours and I somewhat know my way around this car. Lots of swearing and a few beers. Good luck!

Thanks vandersmith, I did one front in 3 hours so I can only imagine how long the rear will take me! Lucky I only have to do the one!

Unfortunately this weekend I ran out of time to get started on the rear Although now that I've done the front I have noticed a small knock after driving around for a bit?? Drop links, springs, top bearings and dampers were all replaced by the previous owner <20k ago. Could it be time for new inner and outer tie rod ends? Beginning to get on the "I hate diagnosing suspension faults" bandwagon... Don't have any records of tie rods being replaced so maybe I'll start with them? Although the steering rack was reconditioned but it makes no mention of the inner tie rods. Ugh

Jack up one side and see how much play you have in the wheel. If you have a lot of play side to side and not up and down it is tie rod. Play up and down is wheel breaking. Make sure the top hats are tight on your shocks and also the nut on the LCA ball joint is tight. I have had both of these issues on the track and they make scary noises.

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Thanks slakker, if I grab the wheel at 3 and 9 and push/pull forwards and backwards I get some play. Maybe around 2-3mm it was the same on both sides. Enough to warrant replacing them?

Not in my opinion unless you are getting excessive tire wear or sloppy feel. Regardless, that's not enough to make a clunking sound.

For the front clunk im going to pull out the left side and inspect it. Anyway as for the rear, got the car up wheel off and stalled. I was going to take it apart but there was no one home to give me a hand and I wasnt confident in getting the proper torque to either bolts so I left it for now I can see why its so difficult, there is little to no room for that top nut on the body side!

For future reference, this is what I/we are dealing with: It appears as if the ball joint is on quite an odd angle, is this how it is or is mine worn? Any issues getting the arm back in and putting it back at that angle?

Okay gents put aside some time today to get this done! Here are the steps I took for future reference. 1. Jack up car then secure with jack stand 2. Remove wheel (I used an air gun hence I didn't loosen them first) 3. Remove under body lining, 2 parts require removal (not all the trays). 4. Using an air wrench and an 18mm socket loosen the bolt to the sub frame (I used the air wrench to get it loose then used a open ended spanner + ratchet when it was loose). I kept the nut in place and didnt remove it then removed the bolt. The nut sat in its perch whilst I did the rest of the work. 4. I had to lift the jack a bit more to get the air wrench + 18mm socket under the control arm for the next bolt. 5. Used the air wrench on the bolt until it was loose then undid the rest with the 21 open spanner + ratchet. 6. Push the fork side of the arm towards the inside of the car then wiggle the ball joint free and out then the rest of the arm will follow. 7. Re-install fork first then ball joint. 8. Do up both bolts as slakker mentioned 118 for the control arm to fork and 133 for the subframe. Biggest difficulty I had was that when I bolted up the subframe the control arm hole wasnt clear by a few mm. I spent quote a while trying to figure this out by placing various jack under various arms to try and align the holes, nothing worked. The way I got it done was my brother stuck a thin extension rod from the ratchet set in the hole and pushed while I put the bolt through from the bottom. Knowing that method would have saved me a fair bit of time! Anyway its done now Hopefully this thread helps anyone looking on instructions for the rear as there wasnt a whole lot out there!

Guys im going to replace the passenger front as well. Would it be worth replacing the drivers rear as well? Would mean that I've changed over all 4. Part manufacturing stamp is from 2006 where as the others were 2003 so at some stage it was replaced.