Help! What suspension modifications should I do?

[JMortensen 237]

This is one of the most commonly asked questions asked here and it is also a tough one to answer, due largely to the varied usage of our cars. From the factory the only adjustable alignment angle available is the front toe. One of the main features of a high performance suspension is the ability to adjust the suspension angles, so as the stages progress the adjustablity increases.

 

IF YOU INTEND TO RACE YOUR CAR, GET THE APPROPRIATE RULEBOOK BEFORE YOU START ANY MODIFICATIONS TO MAKE SURE YOU REMAIN LEGAL!!!

 

REFURBISHING A STOCK Z CAR

 

If the car is a street driver and the intent is to have a cushy ride, it may be that a simple refurbish of the stock suspension is all that is necessary. A typical rebuild of the stock suspension will include:

1. New outer tie rod ends

2. New ball joints

3. New rubber bushings and steering coupler

4. Repack/retighten front wheel bearings

5. Replace rear wheel bearings if needed

6. New shocks (KYB GR2, Monroe, etc)

7. New springs OEM replacements and slightly stiffer Euro springs are available from http://www.courtesynissan.com

 

These few things will restore the ride to close to factory stock.

 

MODIFYING A Z CAR FOR BETTER HANDLING

 

If the goal is to stiffen up the car for better handling, then a lot more can be done. I'm going to attempt to show "Stages" of modifications. These are loose guidelines and parts can be mixed and matched, but these are what I feel are typical mods on the Z's that I've come in contact with over the years.

 

STAGE 1 replaces all old parts with stiffer components. This will give you a firmer sporty ride.

1. New outer tie rod ends

2. New ball joints

3. Polyurethane bushings

4. Repack/tighten front wheel bearings

5. Replace rear wheel bearings if needed

6. Aftermarket front and rear swaybars

7. Lowering springs (Eibach, Suspension Techniques, Tokico, MSA, AZC)

8. Aftermarket shocks (Tokico HP, Tokico Illumina, Koni Red)

9. Bumpsteer spacers

 

STAGE 2 is similar to Stage 1 but starts to allow adjustment of alignment angles.

1. New outer tie rod ends

2. New ball joints

3. Polyurethane bushings and Gmachine control arm bushings and TC rod kit (these allow camber adjustment front and rear and also toe adjustment in rear)

4. Repack/tighten front wheel bearings

5. Replace rear wheel bearings if needed

6. Aftermarket front and rear swaybars

7. Lowering springs (Eibach, Suspension Techniques, Tokico, MSA, AZC)

8. Aftermarket shocks (Tokico HP, Tokico Illumina, Koni Red)

9. Bumpsteer spacers

 

STAGE 3 takes adjustability a step further.

1. New outer tie rod ends

2. New ball joints

3. Polyurethane bushings and Gmachine control arm bushings and TC rod kit (these allow camber adjustment front and rear and also toe adjustment in rear)

4. Repack/tighten front wheel bearings

5. Replace rear wheel bearings if needed

6. Aftermarket front and rear swaybars

7. Coilover spring conversion to 2.5" springs. Street springs generally under ~250 in/lbs.

8. Aftermarket shocks (Tokico HP, Tokico Illumina, Koni Red)

9. Bumpsteer spacers

10. Biscuit style bolt in camber/caster plates (EMI, DP racing)

11. Strut tower bars front and back, preferrably triangulated to the firewall in front

 

STAGE 4

1. New outer tie rod ends

2. New ball joints

3. Adjustable control arms (Modern Motorsports, AZC, Z Select)

4. Repack/tighten front wheel bearings

5. Replace rear wheel bearings if needed

6. Aftermarket front and rear swaybars

7. Coilover spring conversion to 2.5" springs. Street springs generally under ~250 in/lbs.

8. Aftermarket shocks (Tokico HP, Tokico Illumina, Koni Red), might be thinking about sectioning strut housings and getting appropriate shorter shocks to fit at this stage

9. Bumpsteer spacers

10. Biscuit style bolt in camber/caster plates (EMI, DP racing)

11. Adjustable TC rods (TTT, AZC, Z Select)

12. Strut tower bars front and back, preferrably triangulated to the firewall in front

13. Roll bar

 

STAGE 5 - at this point you're pretty much race only

1. New outer tie rod ends

2. New ball joints

3. Adjustable control arms (Modern Motorsports, AZC, Z Select)

4. Repack/tighten front wheel bearings

5. Replace rear wheel bearings if needed

6. Aftermarket front and rear swaybars

7. Coilover spring conversion to 2.5" springs. Springs generally over ~250 in/lbs.

8. Aftermarket shocks in sectioned strut housings(Koni 8610-1437RACE single adjustable, Koni 8611-1259 double adjustable, Ground Control Advance Design, Bilstein Sport VW non adjustable P30-0032)

9. Bumpsteer spacers

10. Cut to fit camber plates (DP racing, Carrera, Ground Control, AZC, TTT)

11. Adjustable TC rods (TTT, AZC, Z Select)

12. Strut tower bars front and back, preferrably triangulated to the firewall in front

13. Roll cage with tie ins to front strut towers

 

Above and beyond Stage 5 you get into modifying the chassis itself to allow for modification of the suspension pickup points. There are also people who have adapted suspensions from entirely different cars into the Z chassis. We've had members install 240SX IRS, Corvette C4 rear suspensions. Also for drag racing there have been quite a few "backhalves" where the entire rear section of the frame is cut off and a new frame built in the rear to allow installation of a solid rear end. Popular choices seem to be Ford 8.8 and 9 inch and Chevy 12 bolt rears.

 

Front suspension swaps aren't as popular as of yet, but many GT2 Z racers have fabricated their own SLA (short and long arm) front suspensions.

 

Modifying your suspension is potentially dangerous and you do so at your own risk.

[MatMan 10]

Great info, Jon!

 

Where are you at now, Stage 8.5?

[johnc 724]

Made a couple edits: Koni part numbers and changed "strut" references to "shock."

[tube80z 17]

should caster plates read camber plates?

[JMortensen 237]

Not if you install them with the slot front to back!!!

 

Thanks for catching that Cary, I changed it.

[srgunz 16]

Jon. One thing I did not see mention of was quick steering knuckles. I have those installed with lowered springs. I think they are adding to my bump steer problem. I do not have any strut bump steer spacers installed. I am thinking I will go back to the stock knuckles and bump steer might be better. What do you think?

[JMortensen 237]

I don't think the quick steer knuckles would have any effect on bumpsteer. Ackerman yes, bumpsteer no. Have you checked out the bumpsteer FAQ? It might help you out: http://forums.hybridz.org/showthread.php?t=103886

[endurorider 10]

Arizonazcar.com has some nice stuff too. think i am going to get the wilwood brakes from him.

Fred

[stony 11]

STAGE 5 - at this point you're pretty much race only

1. New outer tie rod ends

2. New ball joints

3. Adjustable control arms (Modern Motorsports, AZC, Z Select)

4. Repack/tighten front wheel bearings

5. Replace rear wheel bearings if needed

6. Aftermarket front and rear swaybars

7. Coilover spring conversion to 2.5" springs. Springs generally over ~250 in/lbs.

8. Aftermarket shocks in sectioned strut housings(Koni 8610-1437RACE single adjustable, Koni 8611-1259 double adjustable, Ground Control Advance Design, Bilstein Sport VW non adjustable P30-0032)

9. Bumpsteer spacers

10. Cut to fit camber plates (DP racing, Carrera, Ground Control, AZC, TTT)

11. Adjustable TC rods (TTT, AZC, Z Select)

12. Strut tower bars front and back, preferrably triangulated to the firewall in front

13. Roll cage with tie ins to front strut towers

 

 

 

John are the front struts you mentinoned above actually shorter then the stock front strut length? I need a strut that is about 3 inches shorter then what the stock fronts are.

[JMortensen 237]

I am not aware of any commonly available strut insert that is shorter than about 1.625" or so than the stock 240Z. They may be out there, but I'm not aware of any.

[stony 11]

OK an 1.625 shorter may work. Is that the Vw insert listed above?

[JMortensen 237]

The Illumina BZ3099 is the MR2 insert and is the right size, I think the VW insert is the same length.

[stony 11]

The Illumina BZ3099 is the MR2 insert and is the right size, I think the VW insert is the same length.

 

So the MR2 strut is shorter by 1.625 as stated above?

[JMortensen 237]

It's been a while since I sectioned mine, but that should be correct.

[stony 11]

Well i finally got my vw struts. the body is 12.5 inches long and the strut total length is 19 inches or so.. This is perfect and will lower the car ALOT and gain some suspension travel.

 

They are larger in diameter then the konis i had which means they dont slip up into the the strut tube nut like the konis did. Is this bad? do i need to get a different upper strut gland nut? if so anyone have a part number or ideas?

[johnc 724]

Call Truechoice, push 2 for the Koni shop, ask for Craig, give him your shock part number, and he'll tell you what gland nut you need and that its on backorder back in Holland.

[stony 11]

So i guess i will just get my current gland nut machined to fit:mrgreen:

 

Thanks for the info john as always..... helpful

[stony 11]

OBTW here are the struts I got fro my MOCC up. They were Cofap OEM Scirocco strut insert

Part number 30017

Fully extended 20 inches

Body length 12.5

 

The konis that I had installed were 21.5 fully extended and the body was 15 inches.

 

If I figured it right I will be able to section the struts 2.5 inches and this will put me right where I want to be as far as ride height

[Guest d260z-turbo]

well i really like to be at stage 4 or stage 5 no more no less that is it for now. so i just like to get a really good coil over set up for it

so can you guys let me know what a good coil over set up that i can go with

[G.I.jonas 10]

well i really like to be at stage 4 or stage 5 no more no less that is it for now. so i just like to get a really good coil over set up for it

so can you guys let me know what a good coil over set up that i can go with

 

Ummm? dude? i read in another thread you posted in that your datsun is RB'ed with awd.Now i cant help but wonder how you accomplished this and still have an s30 based suspension to work with for upgrading.Do you have any pics of this alleged setup?

[ZDreamin72 10]

now i know that this is probably goina be a biased argument...but which of the companies is best for parts...each part mentioned in which i wanna look at in stage four is asociated with two or three companies that make their style. Can anyone give me some pros or cons associated with each companies piece, if you would buy again from the same people if you did it all over again, which is the best bang for buck, etc. Companies associated with the product in question are all welcome to give me their eplanations as to why they did what and didnt do this that and the other.

[col 10]

KMack has camber tops that also adjust caster. They have what looks like rings with offset holes so when twisted you can get just camber, or by moving the pivot back or forward as well you also adjust caster.

Has anyone used these?

I know you were joking about having the camber tops slotted back to front ,but these do both.

I would think they would be good in the rear.

Do you think adding some caster in the rear would be good?

[JMortensen 237]

In screwing around with the rear suspension I've found that the most important thing you can do is to make sure that the strut is perpendicular to the control arm and the strut top. Any movement of the top or bottom forward or back puts a bending load in the strut. Realistically the control arm will bend before the strut does, but this process still puts stress on the arm and also the side force on the strut can't be good for stiction.

 

Here's a related thread with a solution that nobody has finished yet:

http://forums.hybridz.org/showthread.php?t=129154

[Z lion 71 0]

WoW! thanks john.this answered alot of my questions on a post above.great write up thanks for taking the time to put up all the info.

 

Mike

[kamikaZeS30 11]

I'm an idiot that can't seem to find the old strut thread.

 

When you say sectioning the strut tube housing, do you mean cutting off the stock spring perch to allow for installation of coilovers w/ adjustable collars? Is there a magic length it should be when finished?

 

P.O. of my Z already had installed some coil overs with Tokico HPs. I'm not sure what brand they are, they're not weld-in, but they're pretty stiff, I think they're 200 or 225 lbs/in. rate.

 

I'm asking because I'm trying to figure out my suspension set-up while I'm doing the V8 swap (it's going on 6 months now, but very close to being finished). The ride-height seems "high" not like 4-wheeling or anything, but it looks close to stock. I'm also running a tire diameter of 24.9" (225/50ZR16) so that would obviously have something to do with it.

 

I recently purchased but have not installed yet, polyurethane front & rear LCA bushings. I have already replaced the steering rack, and differential mount bushings when I mounted the V8 (steering coupler is in the mail). I also have a set of RCAs (the ones from MSA for "15 inch and larger wheels").

 

I guess my question is, how does one verify whether or not one is near or at stock ride-height, I mean, I've got bumpsteer like I'm lowered, but apparently that is inherent to the Z suspension? I would like to a go little bit lower with the car (maybe another .5", as it is I need to roll my rear fenders a tad). I figure that if I needed camber adjustment I could drill out maybe an additional 1/4" in the shock tower bolt holes for adjustability.

 

Any advice would be appreciated, and if this is the wrong thread, I apologize.

 

edit: I forgot to mention I have the Bad Dog rails and a triangulated STB in front and rear.

Edited October 27, 2010 by kamikaZeS30