User Login    
 + Register
  • Main navigation
Login
Username:

Password:


Lost Password?

Register now!
Fast Search
Slow Search
Google Ad


[Datsun 1200 encyclopedia]

Suspension upgrades

From Datsun 1200 Club

Datsun 1200 encyclopedia | Recent changes | Edit this page | Page history | Switch to MediaWiki mode

Printable version | Disclaimers | Privacy policy
Categories: Fibreglass | Suspension Modifications

Contents

Your First Suspension Upgrade

B210 Sway Bar Upgrade

Bolt a B210 (1974-1978 Sunny) swaybar on. For around $20 and an hour of your time, it bolts in without any mods:


what a difference it makes I can't believe the difference I can finally go around corners at a decent speed.

For anyone who's looking for a quick and cheap handling improvement this is the way to go.

4849.jpgAlbum click to view
See main article: B210 Sway Bar Upgrade

Competition Suspension Manual

See Datsun 1200 Competition Suspension Manual

Handling versus Roadholding

Handling is the quality of the car during dynamic changes: how it reacts while cornering, how it responds to sudden changes of direction, what happens as you approach (or exceed) the limit of cornering speed, etc.

Roadholding is more concerned with grip. Some cars grip smooth pavement exceptionally well, but their handling manners are not great. For example, they can corner extremely fast, but may be twitchy, prone to oversteer, be unstable over bumps or have other serious faults. Interestingly, the best modern factory cars will pull 1.00g, e.g. Corvette, Porsche 911 GT, etc. More average modern sedans pull about 0.65g (these numbers vary by the diameter of the testing circle, so don't be too concerned about ratings). You can use a G-Timer (about $200 USD) to test g-forces of your car.

Handling is probably the more important factor for a street car. You want a car that handles safely under all conditions and is predictable.

For more information, see the "General Handling" section towards the end of the Datsun 1200 Competition Suspension Manual.

With such a light-weight car as the 1200, it is difficult to improve handling without reducing the ride quality. For a circa 1970 automobile, the 1200 has very good handling (e.g. better than most period 'muscle cars'), but it doesn't compare well to modern suspension technology. Unfortunately, most of the handling improvements will make your 1200 ride rougher than stock.

Stock Suspension

The stock 1200 suspension will give you the smoothest ride, with reasonably good handling characteristics. It sits surprisingly high, which is good for off-roading, but not optimum for cornering on pavement. However, if you lower it, you'll get a rougher ride. The McPherson struts provide the damping force for the front suspension, are surprisingly smooth if in good condition. The rear shocks however, having to damp the relative heft of a live axle suspension, ride fairly rough. That's just normal for light cars without Independent Rear Suspension (IRS).

If you don't want a rougher-riding car, stick with the factory suspension. Just make sure all the steering linkage is in good condition:

  • Steering Gearbox Adjustment to take play out of the steering. Do this first.
    2189.jpgAlbum click to view
  • Ball joints: If they are loose, replacements are available just about anywhere
  • Idler arm: NAPA, or any store sells bushing replacement kits which is OK if the ball end is not worn (loose)
  • Drag link
  • Pitman arm as a ball end that can wear

Also:

  • sway bar bushings. make sure the bar is tight in the brackets. Replace the bushings as necessary. Also, make sure the side of the bar with factory white paint mark is installed on the left side of the vehicle
  • tire size is 155SR-12
  • Optional radials versus standard bias-ply? The factory optional radial tires are the go. They track straighter, last longer, and are more available. Bias-ply tires do often feel smoother though.
  • Wheel offset. Keep it stock to avoid scrub problems (more details below)
  • Tire pressure: 24 psi. Higher pressures will create a rougher ride, and will wear out the center of the tire tread
  • Tire profile. The default 78 or 80 series (tall profile) is the smoothest. Low profile 70, 60, 50 or lower profile tires increasing become harsh riding

Also keep the rear suspension in good shape. The low-friction material between the leafs should be cared for (see the excellent discussion Leaf spring ride quality).

And lastly, good shocks are a must. Push down on each corner of the car, and let up suddenly. The car should bounce only 1 time. If it bounces multiple times, replace the shocks. Note that "gas-charged" shocks and struts will ride rougher than the stock parts. The gas-charging firms up the suspension, hence their popularity with large sedans that start with a 'wallowing' ride quality. Since the 1200 already has a firm suspension they will just make it ride rougher. This may be useful for racing, but not if you value a smooth street ride.

Using a factory-quality Strut rebuild kit (rather than removing the factory strut parts and replacing with a new strut 'cartridge' insert) is the way to retain a smooth front-end ride. On the rear, the factory shocks are the smoothest, though 'adjustable' shocks may work just as well if you can find them. Factory B210 shocks also fit and have similar damping quality. Aftermarket struts inserts and rear shocks are generally firmer.

Modified Suspension

Modifying the suspension for increased handling and roadholding traditionally takes this course:

  • Camber adjustment modifications -- increased camber & adjustability
  • Increased caster -- for better on-center feel and less wandering
  • Adjustable ride height (for race cars)
  • Lower center of gravity -- The stock front springs are replaced with stiffer, shorter units. The rear leaf is eye-reversed or reverse cambered. 2-inches is a common drop
  • Improved brakes -- The stock 1200 brakes are discarded and the struts replaced or modified to accept larger discs and calipers
  • Roll stiffness -- Replace the stock bushings with stiffer parts, use stiffer springs, and fit heavier sway bars
  • wider, lower-profile tires for increased traction

For off-road rallying:


You may want to go to slightly heavier springs in the front...it wouldn't hurt to even lift the front slightly, it helps out with ground clearance. Making the bottom arms longer will give you more negative camber and at the same time more +ve castor...both a good thing. The rear needs more work. I have always set mine up to be soft in the rear. This gives more weight transfer onto the back resulting in better traction. You need to take that extra leaf out and don't make the shocks too hard.2 top links mounted forward help to locate the diff and prevent axle tramp. This is a good basic setup and can be done at minimal cost. These cars do handle better on gravel with the back being lower than the front. You also need to set your brakes up so that there is more bias on the back than the front...this helps to prevent sledging (caused by the front brakes locking up and preventing steering), and lets you set the tail of the car up into corners by locking the rear brakes first. reference

What about Polyurethane Bushings?

Road racers like polyurethane bushings (Delrin, Nolathane or Softride (NOLTEC's brand name), these can be rough on the driver and the car, but make it handle better by reducing the "give" in the bushings. This results in quicker turn-in and more consistent response to varying suspension road forces. You may be able to find firmer rubber bushings, which are a good compromise between smooth ride and best handling.

references:

Tires and Wheels

Wider Tires?

Wider tires help the roadholding a lot. The downside of wider tires is that fuel economy will decrease due to the higher friction of wider tires.

Adding wider tires to the rear (175mm wide to 205mm wide) will help powering out of corners. 205 is the widest that fits under the stock 1200 rear but you'll be hard pressed to find wheels with the right offset to accomplish this. Wheels with positive offset (fwd-style wheels) and spacers can be used.

Wider tires on the front will help reduce "push" (understeer) going into corners. Push is the tendency to slide off the road toward the outside of the corner. Note that most cars, including the 1200, are designed for some understeer because that's safer than oversteer (which carries the risk of spinning-out). The downside of wider front tires is that steering effort increases. 185mm wide tires (e.g. 185/60-R13) fits under stock front. Just keep the wheel offset reasonable.

With wider tires, the diameter gets larger, which has negative effects: The ride height increases, the speedometer reading changes, etc. But using wider, but lower profile tires can keep the diameter near stock.

Wheels that fit the 1200

To choose the kind of wheels you want, see:

Tire Scrub and Wheel Offset

Too much scrub makes the car a bit unstable under braking and therefore won't generate quite as much cornering grip.

Offset Terminology
1116.gifAlbum click to view

This applies mostly to the front suspension (due to the kingpin inclination angle) and not so much to the rear (where camber is nominally zero due to the live-axle design).

Since this affects handling, you'll want to review:

Tires

Stock wheels use 155SR-12 (155 mm tread width) on a 4" wide wheel. These are optimum for fuel economy as they have low friction.

For information on choosing taller, bigger or wider tires, see: Tire Sizes.

Steering and Alignment

Steering Gearbox and linkage

The complete steering linkage is adequate for competition purposes. This includes the steering gear box, tie rods, tie rod ends, all steering arms, idler arm assembly and the lower ball joint.
4932.jpgAlbum click to view

The B110 (1971-1973) gearbox is connected directly to the steering column. B210 (1974-1978) and B310 (1979-1982) box is separate, and uses a rag joint (flexible coupling) to connect to the column.

When the gearbox gets to be about 15 years old, it wears enough to introduce slop into the steering linkage. A simple adjustment will often remove this play. If your gearbox is worn too much to adjust, replace it with a good used or rebuilt unit. See Steering Gearbox Adjustment.

4921.jpgAlbum click to view

Quick-Ratio Steering

Modifying the steering linkage for a faster ratio makes the car respond quicker to steering input. And you won't have to turn the wheel as far to turn a given amount. With the light front end of a 1200, and thus super-light steering effort, a quicker ratio will not be a problem.

  • You can shorten the pitman arm and idler arm (have a professional welder do it) to gain a quicker steering ratio
  • Rumor has it you can fit the later boxes to the B110 and gain a quicker ratio
  • Rumor has it that corolla arms can be used on a B110

reference: all new steering for the 1200

For a Rally Car:

the front suspension needs plenty of castor....you will have to cut a bit out of the bottom of the front guards to give the wheels clearance but it is well worth it.The steering will be heavier when driving slowly but much better feel when you get moving. I also used early model Corolla steering arms (KE20 or 25 I think) which are much shorter than the Datsun ones, this gives a much better lock and "gears up" the steering. I used the standard sway bar on the front and nothing on the rear for gravel, but used a small bar on the rear for Seal [paved road]. reference

Wheel Alignment


The stock wheel alignment settings for Camber, Caster and Toe-in are very old-fashioned, designed for old roads with crowned road surfaces. Modern cars--even stodgy family sedans--now use negative camber for increased roadholding on flat roads.

For stock settings, see Front Suspension Specification.

-VE Camber (Negative camber)

1.5 degrees negative camber can work well for racing.

See main article: Camber

Increased Caster

More caster will improve on-center "feel" and make the car track better. In other words, it will go straight ahead with hands off wheel.

See main article: Castor

Lowering Springs

Lowering the car makes it handle transitions better. A common way to achieve this is:

  • Fit ready-made lowering front coil springs
  • Re-arch the rear leaf springs (or fit lowering blocks).

For details on this and much more advanced lowering methods, see: Lowering.

Rear Suspension

B110 and B210 both use a leaf-spring rear suspension and a live axle. By contrast, the B310 uses coil-springs on a live axle.

The B110 has the advantage of a light-weight axle assembly using the small H145 differential and this is recommended for all A-series race cars (Nissan Competition only sold LSD units for the H145). The B210 and B310 use a slightly heavier but stronger H150 differential. Lighter is generally better for handling and ride quality, but the H145 only handles about 75 lb-ft of torque, so if you have a larger engine (A15 or larger) then using a larger differential is called for. For more details, see Rear Axle Swaps.

Smooth ride

The stock Datsun 1200 rear suspension rides rough. It tends to bounce on uneven pavement. This is normal due to the stiff springs. Here are some ideas to help improve ride quality:

  • Keep the stock ride height, so that you get the full movement of the shocks
  • Replacing the stock leaves with a fibreglas monoleaf may help with the ride quality (and improve handling simultaneously).
  • Repair the low-friction material between the leaves. See Main Forum discussion POST Leaf spring ride quality
    New rubbing blocks are sold by spring shoppes or online, not the exact Datsun designs, but similar or in full strips out of poly/vinyl or Teflon
    27113.jpgAlbum click to view
  • get new springs made that have a lower spring rate. However, this limits your load-carry capacity (not so good if you carry back-seat passengers)
  • remove the bottom leaf of the spring pack. Again, while this smooths the ride, it reduces cargo capacity
  • carry lots of weight in the back of the car. This dramatically smooths the ride, and won't hurt freeway fuel economy, but will reduce city fuel economy since you'll be accelerating extra weight
  • Do not use gas shocks.
    Click this pic for part numbers for rear shocks:
    3772.jpgAlbum click to view

fiberglass monoleaf springs

967.jpgAlbum click to view

1333_588fe773188dd.jpgPost click for topic 1333_588fe794e318a.jpgPost click for topic 1333_588fe787eeec0.jpgPost click for topic

Crisper Handling

Crisper handling is generally achieved by lowering the rear and firming up the bushings. For details, see Lowering.

Here are some ideas that can be used with or without lowering:

  • Stiffen leaf pack by swapping individual leaves from a B210 (the main spring is slightly different)
  • Get new springs made to your specifications (A good spring company or suspension man will advise on the proper specs for your intended use)
  • Reduce the side-to-side movement of the axle during cornering
  • Staggered shocks. Coupes have the advantage here since their shocks lean in different directions to counteract the torque of the axle. Sedan shocks are straight up and down
  • Reduce Axle tramp on hard acceleration. Though not generally a problem with a stock A12, with more torque or high-rpm clutch-dumping launches it becomes a problem
rear leafB1101977 US B210
dimensions (length x width x thickness)1110 x 50 x 6 (1 leaf)1165 x 50 x 6 (2 leaves)
additional leafs1110 x 50 x 7 (2 leaves)1165 x 50 x 7 (2 leaves)
Spring constant1.96 kg/mm (109 lb/in)?
Laden camber11mm/192kg31mm/219kg
Spring eye diameter front35mm?
Spring eye diameter rear23mm?
shocks (sedan)167mm stroke x 506 length205mm stroke x 527 length
shocks (coupe)180mm stroke x 440 length195mm stroke x 470mm length
Damping force expansion58kg (sedan) 68kg (coupe)44-68kg@0.3m/s
Damping force compression38 (sedan) 45(coupe)26-42kg@0.3m/s

Rear Sway Bar

Although 1200s did not come with rear sway bars, Nissan Competition sold a bolt-on rear sway bar. Search the main forum for details on adding a rear sway bar (a.k.a.anti-sway bar aka stabilizer bar).

Sway Bars
partB110B210Nissan Comp Quickor
front17mm20mm20mm (PN 54611-H2300)25mm (PN 99996-H4301)
rearn/an/an/a19mm (PN 99996-H4351)

Chassis Stiffening

See:
* Tower bar strut bar
* Seam welding
* Rollcage
* Steering Gearbox Brace

Advanced Suspension Designs

front control arm mounting points moved way up
IMG_3002.jpgPost click for topic

A lot could be talked about here. Search the Main Forum for discussions on:

  • four-link suspension
  • three-link suspension
  • five-link suspension
  • IRS (independent rear suspension) conversions have been done to several 1200s and B210s
  • tubbed rear and narrowed axle (to get monster tires on the back)
  • hand brake modifications for racing
  • adjustable ride height
    4743.jpgAlbum click to view
  • Fender flares for wider tires

Search the forums for copious details on these topics.

More Information & References

Retrieved from "http://datsun1200.com/modules/mediawiki/index.php?title=Suspension_upgrades"

This page has been accessed 85,747 times. This page was last modified 10:47, 31 July 2018. Content is available under Datsun 1200 Club.