Step-By-Step Coilover Conversion...

[thehelix112]

Guys,

 

I'm in the middle of doing the P30-0032 bilstein upgrade, and switching to coil-overs on my 280z. I just thought I'd document what I've done so far here.

 

 

The parts:

 

From A1 Racing: (http://shop.a1racing.com/)

- Threaded Alu sleeves: 4 x COK12452-H @ USD18.80 ea

- Lower spring perch/nut: 4 x COK12460-B8 @ USD12.87 ea

- Coil-over top: 4 x COK12465 @ USD13.08 ea

 

From MJMAutoHaus: (http://www.mjmautohaus.com/catalog/product_info.php?cPath=2_12_37_71_293_4710&products_id=1995)

- Bilstein P30-0032 shocks: 2 x P30.0032.SET @ USD199.95 ea

 

From SummitRacing:

- Front QA1 10" 275lb/in springs: 2 x HAL-10-275 @ USD37.88 ea

- Rear QA1 10" 250lb/in springs: 2 x HAL-10-250 @ USD38.88 ea

 

From Motion Industries: (https://www.motionindustries.com/mot.../mi/motion.jsp)

- 28mm OD, 15mm ID bearing: 2 x FNT 1528 BRG @ USD3.49 ea

- 28mm OD, 15mm ID thrust washer: 2 x LS1528 @ USD7.62 ea

 

From Reid Supply: (http://reidsupply.com/detail.aspx?R=DM-14028&ST=Drill%20Bushings)

- 22mm OD, 14mm ID drill bushing: 2 x DM-14028 @ USDnotmuch

 

 

The tools:

 

This assumes a general toolkit with appropriate spanners, sockets, drives and ratchets. Additionally helpful is:

- bench vice

- angle grinder with cutting and grinding discs

- large pipe cutter (I got one that does up to 2-1/8")

- 1" drill bit (had to order online)

- 13mm or 1/2" drill bit

- M14x1.5 tap

- half round file

- hack saw

- welder

 

 

The procedure:

 

Preparation:

 

Step 1. Remove front strut. Make sure you loosen, but do not remove(!) the top damper nut while the assembly is in the car as its much easier to hold.

 

Step 2. Remove the top damper nut. The stock 280z assembly is preloaded so it explodes as the nut comes loose. So don't be sitting there looking directly down at it.

 

Step 3. Using multigrips (aka channel locs), undo the damper gland nut and remove the existing insert/original body.

 

Step 4. Bolt the assembly into a vice of some sort to make it easier to work with. You can remove the brakes to make it lighter but I was too lazy.

 

 

Strut-tube Modification:

 

Step 5. Using a thin cutting disc on an angle grinder, cut the stock lower spring perch off. Do not cut into the strut body, I cut 6mm (1/4") above the weld to get enough distance.

 

[/u] Step 6. Using a grinding disc, grind down the remaining spring perch and weld until it is flat and the threaded sleeve can easily slide past where the weld was.

 

Step 7. Slide the threaded sleeve down until the top of it is 2-1/4" down from the top. Scribe a mark around the entire circumference of the strut tube using the top of the threaded sleeve as a guide. Remove the threaded sleeve.

 

Note: Don't worry, you are not going to be shortening the struts 2-1/4". The female carrier that comes with the Bilstein dampers will be welded onto the strut tube, adding an extra 3/4". So we are taking 1-1/2" out.

The reason this is done instead of sectioning the struts in the typical fashion is that Bilstein do not make a gland nut in the M52x1.5(?) thread to suit the 280z struts, so we use the female carrier that comes with them instead.

 

Step 8. Using the cutting disc, cut anywhere between 1/2 and 1" off the end of the strut. This does not have to be particularly neat, a few mm difference is acceptable. You will be using this off-cut later to stop the threaded sleeve sliding down.

 

Step 9. Cut the strut tube at the mark scribed in step 7 using the pipe cutter.

 

Advice: on the first orbit of the tube, watch the cutting wheel very closely to ensure it follows the scribe precisely. If it does not meet up with itself it will tend to try and work its way down the tube cutting a very shallow thread. Do a few orbits in between tightening the pipe cutter.

 

Step 10. Cut the cut-off from step 8 into three equal concave shaped sections (roughly every 120 degrees).

 

Step 11. Put the cut-off from step 9 into the vice and individually beat each of the three concave shells until they fit nicely against the outside of the tube.

 

 

Female Carrier Modification:

 

Step 12. Using the cutting disc, cut off the smaller diameter section (on which the PN is stamped) of the female carrier. Do not overcut into the conical (tapered) section.

 

Step 13. Using the grinding disc, carefully grind down the remaining small diameter section until the carrier ends at the end of the conical section.

 

Step 14. Using the round file, file the inside of the carrier down until the damper body can fit through it easily.

 

Advice: use the internal steps as a guide as to how far you have filed.

 

 

 

Coil-over-top Modification:

 

Note: Unfortunately, the coil over tops I ordered from A1 racing are clearly not meant to suit the P30 bilstein damper. They require very minor modification.

 

Step 15a. Place the Torrington thrust washer on top of the coil over top and grind down the coil over top until they are both level.

 

Step 15b. Cut the drill bushing into 4 10mm long sections. These spacers centre the coil over top on the Bilstein damper. By making them a little longer than the thickness of the coil over top section, means that when installed the section clamps down while leaving the coil over top free to rotate on the torrington bearings, and keep the steering nice and light.

 

 

Strut-top Modification:

 

Step 16. Put the strut-top in a vice, and using a stanley knife, trim the downwards-protruding rubber lip off 6mm (1/4").

 

Step 17. Using a 13mm (or 1/2") drill bit, drill out the D in the strut-top.

 

Step 18. Using the M14x1.5 tap, tap the hole in the strut-top. This, while perhaps not absolutely necessary, prevents the threads on the damper from being damaged by pressing against the metal in the strut-top during side loading. This helps hold the damper piston stable whilst doing up the top nut later. Additionally, it simplifies preloading the spring, as the top can simply be wound on an inch, providing around 275lb without necessitating spring compressors.

 

 

Welding:

 

Step 19. Get some 1-1/4" OD Alu pipe from which to make the spacers. I initially tried 1 1/2" but it was just a fraction too big to fit through the carrier. On my struts the fronts needed a spacer 9/16" long. Don't forget to test the assembly to ensure the spacer length is good. The gland nut should go solid with between 1 and 2 threads showing. Additionally, this locates the strut housing neatly in the carrier, and should provide additional lateral support.

 

Step 20. Tack-weld two opposing sides (12 o'clock and 6 o'clock) of the female carrier onto the strut. Slide the threaded sleeve down to check that the top of the female carrier is even with the top of the gland nut all the way around. Tap with a hammer and/or re-tack as necessary to get this correct. Slide the threaded sleeve off.

 

Step 21. Weld the female carrier onto the strut body.

 

Step 22. Grind the new weld down to the tube OD until the threaded sleeve can slide on again.

 

Step 23. Position the threaded sleeve so it is flush with the top of the carrier. Tack the three concave shells from step 10 at even intervals around the tube at the bottom of the threaded sleeve. Put the side of the shell with the thread against the sleeve as this side was the former strut top, and is perfectly flat around.

 

Step 24. Slide the threaded sleeve off and weld the shells onto the tube in the lower and vertical sides. Do not weld the top as this flat step is what we want.

 

Step 25. Splash some paint on the cleaned up struts.

 

 

Installation:

 

Step 26. Rub some grease around the tube and slide the threaded sleeve on. The grease will not only help installation, but will provide some corrosion resistance, and thermally connect the strut tube with the lovely heat-dissipating threaded sleeve. Anal-retentive much? Screw on the lower spring perch and put it all the way to the bottom.

 

Step 27. Install the alu tube spacer and damper, ensuring the spacer is sitting correctly vertical. I was a little worried about the strut being supported at the bottom, so I drilled a couple of holes in the solid alu spacer the same diameter/spacing as the holes in the bottom of the strut; and put some small dowels between the two. Hopefully this will make the strut less likely to wobble around during cornering.

 

Step 28. Using either multigrips (channel-locks?) or the Bilstein part number: E4-MS-08/7 (USD4.93 from Bilstein aftermarket) tighten the gland nut down, checking that between 1 and 2 threads still show when fully tight.

 

Step 29. Install the spring preload bearing onto the lower spring perch. Then cut the lower 4 rings off the dust boot and slide the spring over the damper, being careful not to needlessly bang against the damper piston.

 

Step 30. Slide the 10mm spacer, coil-over top, thrust washer, large washer, needle bearing, and remaining washers onto the damper.

 

Step 31. Install the strut-top (with the bearing) by screwing the strut top onto the damper thread, and do up the damper top nut. Important: Check that you can hold the strut top, and rotate the coil over top and spring freely. If you have made the 10mm spacer less than 10mm, then the coil over top could be clamping against the damper top and jamming. Guess how I know.

 

Step 32. Install the whole assembly back into the car.

 

 

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So while my suspension is apart, I figured I'd try to get some adjustable sway bars on the cheap. My plan for this involves modifying the stock sway bars so they can be made both more and less stiff. This is to give myself the opportunity to experiment with a range of suspension setup philosophies. I want to be able to try both ``balance the car with the springs then use a light bar to tune'' and ``balance the car with the bars and run light springs to try and get mechanical grip''.

 

As before, much appreciation to EMWHYR0HEN for his tireless assistance, and for the ride in the beast.

 

So.

 

The parts:

 

From Midwest Control: (http://www.midwestcontrol.com)

- Female rod ends: 2 x (don't remember atm, plus they're very small and might not fit - will update later)

- Male rod ends: 2 x (don't remember atm, plus they're very small and might not fit - will update later)

 

From any metal supplier:

- 1/8" hot rolled plate. Around 1.5" x 2'.

 

 

The tools:

 

This assumes a general toolkit with appropriate spanners, sockets, drives and ratchets. Additionally helpful is:

- welder

- angle grinder with cutting and grinding discs

 

 

The procedure:

 

Step 1. Remove the front sway bar and lower control arms from the car. Hang onto the bushed connector between the two for length reference later on. Wire wheel the end of the sway bar to get it ready for welding. Wire wheel the flat while you're at it.

 

Step 2. Mark and cut parallel to the vehicle centre-line on the inside edge of the hole through which the bushed connector fits. This line should be perpendicular to the main sway bar rod that runs across the vehicle when its installed.

 

Step 3. Cut a length of the flat steel around 2" x 4", and tack weld this onto the flat surface provided by the cut you made in Step 2. Optionally, pre-heat the area, focusing on the bar, for welding.

 

Note: When installed on the car, this flat should extend downwards so be careful that you know which way the sway bar is, so can place the flat appropriately.

 

Step 4. After triple-checking everything is aligned, oriented and otherwise in place correctly, weld the flat onto the sway bar.

 

Step 5. Get the lower control arm, and wire wheel around the sway bar connector attachment hole. Mark a line on the inside edge of this attachment hole. Grind the raised section down until the plate can sit flat. Weld the flat on both sides to the LCA.

 

Note: On adjustable or lengthened control arms (such as mine), the position of the flat will be different. I used a stock control arm as a reference point and lined the two arms up with the inside pivot points even, then marked (parallel to the pivot axis) over from the stock arm's connector hole to where this was on the longer arm.

 

Step 6. Repeat on the other side of the sway bar and the other control arm.

 

Step 7. Test install the LCA and sway bar to ensure that both plates are roughly in the same plane (beat with a BFH until they are), and are not too far apart. Though the rod ends do allow for misalignment, there is a limit, especially with such small rod ends.

 

Putting the sway bar and LCA approximately as they will sit after installation, mark a line vertically approximately in the centre of the LCA, at the same longitudinal position as the original sway bar mount.

 

Step 8. Remove the LCAs and work out how much flat you want. Trim anything you don't. On an S30 the sway bar has quite a bit of free movement without interference (or so I think at this stage?), so as long as you trim both LCAs the same, you should be ok. Make sure you leave enough flat to drill a hole for the rod end to be bolted.

 

Step 9. Drill a hole in the LCAs' flat appropriately on the marked line, to replicate the factory mounting position. You can then drill as many holes on either side as you can fit. I tried to allow for both more and less roll stiffness, so I have holes in either side.

 

Step 10. Cleanup the flat, and hit it with the spray can.

 

Step 11. Remove the sway bar and repeat steps 8-10 for the sway bar flats.

 

Step 12. Install the sway bar and LCA. Bolt one rod end into the holes replicating the stock sway bar position to start with. If nothing else, this will verify that the tiny rod ends are strong enough to not get ripped apart. When bolting into the other side, adjust the rod end as necessary to ensure the sway bar is not preloaded. I.e. don't heave down on the sway bar to get the bolt holes to line up.

 

 

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Just bought some bits for the front brakes from ruggedbert (good bloke).

 

 

Wilwood Integra-4 GT calipers: Used but appear to be in good condition, missing a bleed nipple on one but not a biggy. JSK hats, and Wilwood 12.19" (~310mm) vented rotors.

 

I also have JSK rear rotor hats. So quite a few things left to buy, but getting there. Still need:

 

Braided lines on all corners

Rear discs

Rear calipers - will probably go some small wilwoods to keep it all in the family.

Pads at all corners - most likely Ferodo DS2500 unless they're stupid expensive over here.

 

Trying to find time to finish the coil overs and suspension. I hope getting the rear control arms will be the stimulus required.

 

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Made a little bit of progress on getting it all back together yesterday.

 

I pulled out the old 3.54 diff, and cleaned up the cover and all the rear sub-frame for installing the 4.11. I painted the rear subframe black, but left the rear diff cover bare alu.

 

I also got the local auto shop with a hydraulic press to push the pin out of one of the rear strut stub axles, and then dropped off the strut for the other side to them as that one doesn't want to budge either. So I assembled the coil over for the one that I got back.

 

Here is the left rear coil-over installed.

 

And here (not really visible) is the cleaned up rear subframe including new bushes in the moustache bar.

 

So all that remains is the final coil-over, bolting the cover onto the 4.11 diff when I get a new gasket for it, reinstalling it, and then bolting up the rear lower control arms. Oh and greasing the front tie rod ends and ball joints, and an alignment (and perhaps corner balancing).

 

Hopefully not too far away.

Edited March 16, 2011 by RTz

[RB26powered74zcar]

5 stars for this excellent documentation Dave! I really like the adj. sway bar mod.

[RTz]

Stuck/pinned/glued.

[JMortensen]

Did you push the suspension through its full range to check for binding on the bar? I was surprised at how little room for error there is when I did mine. Your's might have a little more give since you presumably have sway bar bushings attaching the bar to the frame.

[thehelix112]

Jon,

 

No I did not. The front bar needs proper misalignment bushings, and likely some larger rod ends. I figured (like an idiot) that I'd start with a smaller size and if they snapped upgrade to larger ones. Perhaps not the safest thing. That being said, its hung together for a few twisty roads. Would definitely make sense to just get some larger ones initially and invest in proper misalignment spacers. I will put the front through its range of motion when I rework the coil over tops to go with TTT strut tops. Did you use mcmaster carr misalignment spacers? Any recommendations?

 

Dave

[JMortensen]

I just used 3/8" tube cut to 1/4" lengths. I think you can probably go smaller than 3/8" rod ends, maybe 5/16", possibly even 1/4, but if they're binding I think it's just a matter of time before something breaks. I had to do 3 attempts on the rear bar in order to find a position that didn't bind. The front went better, but it was still pretty hypersensitive to position of the bar. I think part of that may have been because I was trying to make it work through the full range of motion. I later decided to run much stiffer springs. Had I known that when I started, I would have focused on a much smaller range of motion. I think with your spring rates you need to be concerned with a pretty full range though. If you plan on running the car low, you can probably disregard what is going on at full droop, but aside from that I think you'll be using most of the suspension with rates in the 2-300 range.

 

When you test for bind, don't do it with a jack. Just take the spring off and manually push the suspension up with your hands (sway bar has to be disconnected from the other side).

[thehelix112]

Sounds good. Will do.

 

Thanks,

 

Dave

[shika805]

good stuff!

[MREDDLE]

LOOKS GREAT

[thehelix112]

thanks guys. Next thing will be mating the bilsteins to TTT strut tops.

 

Dave

[sileightygx]

awesome progress and GREAT write up!

[AFCrain]

I'm new to the Z world and must ask the stupid question of the day. Will this process work on the early 74 260? I know there aren't too many radical changes throughout the early years, but this is a great walk through with an extra goody(adjustable sway bar). Kudos and hopefully my nievity will disappear with experience.

[texis30O]

Other than camber plates what else would be needed?

[Chapz]

Very nice documentation. Good jod on your car and on the internet post.

I hope there's have someone who can give an answer to post # 13

Edited January 12, 2012 by Chapz

[thehelix112]

chapz,

 

Thanks for the compliments. its definitely a 15' car, but getting there. If I understand the question to be what else is needed to mate the TTT tops to the Holstein struts the answer is I don't know yet. I'll post details when I do it here though.

 

Dave

[Jasper280Z]

Hi everyone,

 

I'm new to Hybridz.org and I greatly appreciate you more experienced users putting together instructions like these. I am currently planning to building coilovers like these with Tokico Illumina shocks, and either Ground control coils or some H&R springs.

 

Does anyone have help full tips for picking out springs?

 

Jordan

[tamo3]

Which gland nuts did you use?
Did you use VW gland nuts comes with your P30-0032?

Or did you get 51mm x 1.5 gland nuts somewhere?
If you so, could let me know where did you get it?

Thanks,
tamo3

[thehelix112]

tamo3,

 

I used the gland nuts and female sides that come with the the dampers.  The females were ground down and filed out then welded onto the top of the strut tubes, this is Step 13, 14 and 21.

Best of luck!

 

Dave

[tamo3]

Thanks Dave for the information. I missed step 21, 22. Now I got it!

[mattd428]

nice