Upgrade bolt in suspension or go straight to coilovers?

[CasperIV]

As the title suggests, I am looking for opinions on which direction I should head with my new Z project. I have been searching and reading other peoples builds as well as the how-to sheets for the coilover conversions. While I feel confident we (me and my friends that do fabrication) can handle the conversion, I like the idea of leaving the car unmodified and using bolt in parts. Since the voices in my head are deadlocked, I want your guys opinions based on my current goals/plans.

 

Sould I go with a bolt in suspension upgrade along the lines of Tokicos and springs (here) or is this something that there is a good chance I would out grow quickly and replace with coilovers? The coilovers I have been looking at are the Arizona Z kit (here). I have been out of the Z world playing with my S2000 for quite a few years and it would seem a lot has changed. It would be helpful if you could provide a little bit of the reasoning/lessons learned that formed your opinion as well.

 

Here's a run down of my build direction:

 

Platform Car: 73 240Z nearly stock (5 speed swapped, rear end seems taller geared than my last 240).

 

Purpose: A performance street car that will be autocrossed (mostly for fun locally). Would also like to do track days if I ever have free time and will probably visit the late night drags for fun with my friends cars.

 

Other near future mods:

• Looking at the Arizona Z Wilwood 5 lug competition kit front and rear (here), most likely just the 4 piston.
  
• Minimum of a roll bar w/ harness bar (a more full cage) and other chassis stiffening improvements.
  
• LSD Swap (Not sure which direction I'm heading with this yet).
  

 

Looking to do the suspension in the very near future (looking to make a decision and order within a month or so). I hadn't driven a fully factory suspension 240Z before and it feels like a tractor to me Once I feel that I like the suspension/brake/chassis setup I will finalize my engine plans.

[Zmanco]

Simple answer: If you don't go with coilovers, you'll be bolting in adjustable LCA and TC rods. Those parts are not cheap, and there's very little to choose from for springs. And you'll be limited to about 3 deg caster. If that is not enough to hit your performance goals, then coil overs are the better way to go.

[JMortensen]

You can't do camber plates without coilovers, and you'll need camber plates for any real autoxing. If you get the "biscuit" style camber plates, you don't have to cut up the car, but the adjustment is more limited. Design Products Racing sells them.

[jhm]

If you're looking at the various coilover options, don't forget to check out Cosmo Racing coilovers. I believe they offer one of the cheapest and simplest kits. (They also have limitations, like limited total travel.) My link

 

The real answer depends on your desired application. If you truly will only be using the car for "local fun autocrossing", there are plenty of non-coilover solutions that might meet your needs. However, many guys decide to get more serious about racing once they start, and end up having to redo mods in order to make the car more competitive.

 

Good luck.

Edited August 15, 2012 by jhm

[CasperIV]

Yeah I am working on heading toward the "less serious" direction with racing. It started feeling more like work than I would like and now that I have sold off the S2000, MR2, RX-7, etc, I don't have dedicated race vehicles. I jumped completely out of it for a while and only want to go back if it's fun. This car may not be a dedicated racer, but I think you guys are right that I would just end up frustrated and replacing everything else trying to get the adjustments I wanted. Short of 500HP+ at the wheels, the cars just won't feel that fast, so I really like them to handle and brake well (by not fast I'm referring to the fact I generally DD my Ninja 1000 or 636).

 

Thanks for the input.

Edited August 15, 2012 by CasperIV

[johnc]

From your post it doesn't appear that you want to be competitive at autocross. Open track events are by nature not competitive. Before you starting thinking about mods, you need to make sure the basic car is safe, sound, and reliable.

 

Get under the car and check the chassis for rust. Fix that first.

 

Make sure the seats and seat mounts are good and solid, check the seat belts and pedals. Make sure the doors close properly and the door locks work.

 

Check the ball joints, tie rods, steering rack, steering shaft and coupler, all the nuts and bolts, brakes, brake lines, wheel bearings, hubs, spindles, seals, engine, trans and diff mounts, shocks, anti-roll bars, bushings, e-brake, and everything else to make sure its all in good working order.

 

Make sure the cooling and oiling systems are good and can handle 30 minutes of track time with half of that time at full throttle. Change all the fluids. Replace all the belts and hoses. Fix any fluid leaks. Do a complete engine tune up including valve adjustment. Go through the engine wiring harness and fix any problems. Make sure the alternator charges. Put covers over the battery terminals. Adjust the clutch. Check the driveshaft and halfshaft u-joints. Bleed the brakes and the clutch. Lube the front suspension and driveline.

 

Once you've done the above you'll have a safe and solid car that can run on a race track for 30 minutes.

[johnc]

Now for the mods:

 

1. LSD should be the first thing. It is the single best mod you can make to improve lap times and handling in a S30.

2. Repalce selected suspension bushings with urethane. You don't need adjustable LCAs to get a good handling car. They do make alignment a bit easier.

3. Springs, shocks, camber plates and anti-roll bars should be done all at once. Coil overs should be where you go based on your past experience and goals. You can do the AZC stuff or build your own from kits I or Ground Control sell.

4. Alignment. Next to the LSD, this is critical to get an S30 handling well. These cars are very sensitive to alignment.

5. Roll bar is a good idea for safety. I do not recommend a full cage in a street driven car. A small accident can become a major concussion. Also, you'll need to upgrade the seats to FIA certified seats if you're going to run a harness. The Scroth 4 point with ASM is a good harness setup for a street track car.

6. Brakes are optional. I've raced SCCA ITS with the stock brakes and, with proper maintenance, pads, and cooling, they work with really good balance. Lots of different upgrades available but most make the brakes very front biased. If you know how to brake well, pick your brake upgrade carefully.

[CasperIV]

From your post it doesn't appear that you want to be competitive at autocross. Open track events are by nature not competitive. Before you starting thinking about mods, you need to make sure the basic car is safe, sound, and reliable.

 

Get under the car and check the chassis for rust. Fix that first.

 

Exactly. Before I bought the car we actually put it on a lift and checked the under side. I pulled the carpets and looked where I could for rust, and made a list of basic repairs.

 

 

Make sure the seats and seat mounts are good and solid, check the seat belts and pedals. Make sure the doors close properly and the door locks work.

 

All that is in order, but the SU's seem to need to be reconditioned. According to the previous owner there was a little play in the shaft to the throttle which made it stiff (hard to gently rev) and he was right. I can live with this minor annoyance but it will have to be dealt with. As for the seats they are in good shape, solid, but only have factory lap belts... that will be changed as soon as I figure out how I want to do the harness system and how extensive the modifications for the new seats will be.

 

Check the ball joints, tie rods, steering rack, steering shaft and coupler, all the nuts and bolts, brakes, brake lines, wheel bearings, hubs, spindles, seals, engine, trans and diff mounts, shocks, anti-roll bars, bushings, e-brake, and everything else to make sure its all in good working order.

 

Brakes are all good and peddle is firm. They were replaced not long before I purchased the car and are still in great condition. Brake lines seem to still be in good shape, but I will be doing some deeper inspections when I start pulling the wheels. Engine and transmission were recently rebuilt, engine runs like a top and sounds healthy. E-brake works well. The suspension in general seems good but very dated. I need to get the car back up in the air with the wheels off so I can look for leaks, and start digging. From driving impressions it's in decent shape but I want to replace it.

 

I am a bit concerned about the diff mount situation. Under hard shifting it feels like it maybe a little sloppy. When it was in the air it looked ok, but I was mostly hunting for rust/broken/missing items.

 

Make sure the cooling and oiling systems are good and can handle 30 minutes of track time with half of that time at full throttle. Change all the fluids. Replace all the belts and hoses. Fix any fluid leaks. Do a complete engine tune up including valve adjustment. Go through the engine wiring harness and fix any problems. Make sure the alternator charges. Put covers over the battery terminals. Adjust the clutch. Check the driveshaft and halfshaft u-joints. Bleed the brakes and the clutch. Lube the front suspension and driveline.

 

Cooling system seems to meet the minimums, but I would like to upgrade it. At 90+ F ambient it was getting about 3/4 toward hot on the factory gauge (which works well) running 4k-6k rpms for about two hours of driving. Engine tune up and hoses were done at rebuild it seems, all look in very good condition. I will be addressing fluid changes this weekend.

[CasperIV]

Now for the mods:

 

1. LSD should be the first thing. It is the single best mod you can make to improve lap times and handling in a S30.

2. Repalce selected suspension bushings with urethane. You don't need adjustable LCAs to get a good handling car. They do make alignment a bit easier.

3. Springs, shocks, camber plates and anti-roll bars should be done all at once. Coil overs should be where you go based on your past experience and goals. You can do the AZC stuff or build your own from kits I or Ground Control sell.

4. Alignment. Next to the LSD, this is critical to get an S30 handling well. These cars are very sensitive to alignment.

5. Roll bar is a good idea for safety. I do not recommend a full cage in a street driven car. A small accident can become a major concussion. Also, you'll need to upgrade the seats to FIA certified seats if you're going to run a harness. The Scroth 4 point with ASM is a good harness setup for a street track car.

6. Brakes are optional. I've raced SCCA ITS with the stock brakes and, with proper maintenance, pads, and cooling, they work with really good balance. Lots of different upgrades available but most make the brakes very front biased. If you know how to brake well, pick your brake upgrade carefully.

 

Excellent points. I didn't think I would ever go full cage with it (even without wrecking I hate hitting my head getting in and out). I hadn't really ranked the LSD that highly, but it makes sense. I have taken for granted most of my more recent cars had good LSD's from the factory.

 

Thanks for the great info.

[duragg]

I struggled with all these questions and held off making any big suspension changes. The LSD is the single most enjoyable part of my Z, so his list is right on: "Power steering"...

 

I decided to start collecting parts for a total suspension swap. Now I have spare tubes, new stub axles, coilovers, bushings, camber plates, spindle pins etc.

Once it is all ready I will swap the whole setup and be done forever. I am replacing the the brakes for looks and a cool profile tag-line more than performance to be honest.

 

In the long run the cost to do Coilovers with the benefit of selectable ride-height just seemed like the correct cost delta for me.

Having spare tubes just made the setup flexible with my schedule and I do plan to offer them (the uncut removed set) to the community once I am done.

[Michael]

John, you didn't mention wheels/tires. Maybe this is obvious, but some of us obtuse fellows (such as yours truly) are still running on suicidal 20+ year-old tires, because our cars have been on jackstands since the 20th century.

 

When a car emerges from lengthy hibernation, the necessities of making it safe, can easily snowball into making it goldplated. Tires choices suggest new wheels, new wheels beg for new brakes, new brakes precipitate shock/spring mods which lead to coilovers and camber plates and so forth.

 

For dragstrip use, I'm contemplating welding my spare differential, instead of going the LSD route (mostly because of cost). Is this reasonable?

[johnc]

Tires are a given. They should be replaced every 7 to 9 years regardless of tread condition.

[BluDestiny]

Yes a welded dif is fine, watch out for rain/water, you'll get chirping at low speeds blah blah blah you've probably heard it. I'm pretty sure JohnC used a welded diff or autocrassing at some point.

[letitsnow]

If you want cornering grip make sure you go with a ~200tw tire, going from 300 down to 200 will net a TON of grip, 1-2 seconds on a 60sec course in an autocross.

Edited August 21, 2012 by letitsnow