Suspension/ steering setup post registration

[Morris]

I haven't seen this discussed on this (or any other XI) forum so now might be the time to gather people's views.

I built my XI straight up with the Protech longer travel coil over shocks, and I'm very happy with the comfortable ride and good handling. The steering geometry is as per the Westfield Build Guide and I've set the tyre pressures to be 27 psi at the front and 20 psi at the rear.

Whilst out over the weekend on a (maybe overly) spirited drive along the leafy (but undulating) Hertfordshire country lanes, I experienced a couple of incidences where I may have deviated from my line of trajectory after driving over a smooth, but deep dip in the road.

This all happened quicker than my conscious mind could register, so I can't say for sure whether or not I moved from my side of the road.

Thankfully, my intended direction of travel and speed remained as planned so all was well.

I expect there has been much experimentation of suspension/ steering setup with the Protech units by members of this forum, especially in the US where (I believe) this setup was first trialled.

All comments and advice most welcome.

[Westfield 129]

You have experienced BUMP STEER! Now you know what it feels like, rather than hearing about it, but not knowing how it might affect your driving. While there is on real way to fix this on the 11, you an minimize it to a point where it is not a factor. Ride height and tracking are the important elements to correct this.

The first thing to check is the toe (tracking) with your weight in the driver's seat. This is incredibly important, as not aligning the car with the driver in the seat will create horrible "bump steer" (the steering of the front wheels though the car's suspension travel). Hitting a bump or a big dip can send the car in whatever direction that the wheels become pointed... and not necessarily where the car is being steered. (remember that changing camber will change the tracking, so make sure that the ride height, and camber are at the right settings WITH THE DRIVER IN THE SEAT. This driver in the seat thing is the key to any very lightweight car setup.

Generally, what happens is that when the tracking is set with the car empty, the toe goes way out, creating lots of instability. Steering will go ultra quick and bumps will send the car off your intended path. Putting 27 lbs in the tires will make this horribly worse. Remember, your 11 is only about 1,200 lbs with you in it, so having a passenger car tire pressure is completely silly. With the driver in the car, only about 51~52% of the weight (or less) is on the front wheels, so extra tire pressure is not necessary. Remember, when you only need about 18 lbs, a 7 psi increase is a huge % increase in tire pressure, and then the tire gets hotter... Back off to 20 psi front and rear, or lower. Having a pyrometer can help with this, and make sure that your tread is on the road, and not just half in inch of the middle of the tire.
I run only 18 Psi in my 185/70/13s, and never more than 20 psi all around. Any more air pressure and the car will become skittery and unstable.

Set the ride height, camber and tracking with the driver in the car! You may have to cut the tie rods to be able to make the adjustment. In some cases, the tie rod end has to be cut down as well to make room for the jam nut. If you have scales available, look for "ZERO WEDGE", OR 50% of the weight on the diagonal, as in LF to RR.

Front end ride height should be around 5" up front, with an extra half to 3/4" on the driver's side EMPTY to start. Rear should be about 7", again with about 1/2~3/4" higher on the driver's side.

With the driver installed the ride height should be 5" up front (measured under the frame at the front axle centerline) and about 5~6" in the rear, measured at the frame, under the axle. This should give enough suspenion travel.

With the driver in the car, and the ride height adjusted, set the camber at -1º~ -1.5º. Toe in at 1/16" total. Camber should be equal on both sides. Caster should be around 4.5º. This is not adjustable, but the frames are pretty accurate, and the number should be the same on both sides.

If you don't have the front anti roll bar, get one. Don't forget to drill the mounting blocks for a grease fitting. You might want to invest a few quid for some proper turnbuckles and LH and RH threaded rod ends so that adjustments can be made without having to take everything apart. This is important when setting up the suspension, as the tension for the roll bar has to be taken out with the driver installed. Just insert this bit of information at the end of your ride height setup. The bar has to be neutral WITH YOU IN THE DRIVER'S SEAT.

If you have the Protech double adjustable shocks, you have a setup that I started working with about 15 years ago. The setup is as follows:

Once you have set the ride height, you will need to set up the shocks. The shocks may be set too stiff even on the softest setting, so you will need to make two adjustments to reduce the total damping force. Check your shock documentation as to how to do this. Not difficult, but probably necessary.
If you can't get the shocks to be soft enough, you may have to make a couple of adjustments (half turn adjustments to the original setting from Protech) to get a range of adjustment that you can use.

Then, drive the car with both rebound and compression set to minimum. Start at the front.

if the front end is floating, adjust the compression one click at a time until the ride becomes jiggly. Then back it off one click. Then adjust the rebound so that you don't get a kick in the butt, or a bouncy ride when you go over a bump. The chassis will become more stable and not "float". If it becomes harsh or jiggly, take off one click.

Then you can move to the rear using the same procedure. If you get it right, the car won't bottom on most bumps and will absorb bumps and dips with a dead beat, like a Mercedes. No bounce. Just bump absorption and stability.

Oh, and you can mount the Protech dampers with the adjusters up top so that you can reach them and at the same time, keep them out of the dirt.

If you have any problems getting the setup to work, don't hesitate to get in touch with me here. Jon has my Email as well.

[Morris]

Thank you Jan. You're the font of all XI related information so I'm grateful for your full reply.

First of all, my shocks are have single adjustment, but what you are saying is still valid and I expect they're not set soft enough.

I've set the tyre pressures higher at the front to help with self-centering of the steering (from when it had it's IVA test). Tbh, it's still very poor so I haven't gained any benefit of the higher pressure, so I'll make that adjustment.

Wrt ride height, where do you measure it? We have many speed humps where I live, so I'm in constant fear of clouting the sump, although I usually try to hit them off-centre.

I set up the tracking without being in the car which I know gives a false set-up. There's clearly a lot of work to do to get the geometry right and to reduce the bump steer. I'll give it a go to see if I can improve things.

In general, the car handles very well at sedate speeds, so I must have been reasonably close, but these things only come truly into play when driving in a more 'spirited' fashion...

Thank you again.

[Westfield 129]

Ok, even more information.

The W11 has plenty of caster, so self centering should not be a problem, UNLESS YOU SET THE CAMBER AND TRACKING WITHOUT YOUR WEIGHT IN THE DRIVER'S SEAT. I have corrected this problem on a number (4 to be precise) W11s, all with the same problem... Too much "toe out". Once this is corrected, your steering will have plenty of feed back, response and caster return. With that setup, you get no caster return, and whenever the suspension is compressed, the chassis will head for the hedges as each front wheel steers independently. If you set the tracking without the weight in the car, the tracking will be out by a full inch or more. This is really a problem when the accepted measurement is 1/16". You are not the only one... Every 11 I have encountered ('cept the ones that I built) have had this problem, and had instability and braking problems. It's one of the things not covered in the manual.

I am sure that once you get the chassis properly set up, you will find the car far more enjoyable. I have run mine on 1000 mile tours. The handling is excellent, and straight line stability is exemplary and the ride relatively smooth. One thing... You will need your cutoff tool to remove some of the tie rod threads, and you might also want to get a thin jam nut for the tie rod end as well. Sometimes, you will need to cut down the tie rod end, as well as the rod end itself, and a thin nut will be needed to ensure that you have enough threads to make the adjustment. Don't be bashful about being a perfectionist in getting the front end set properly. Get it right, and the whole car becomes more natural and fun to drive.

Going a little farther into this front end setup problem, it is important to get the torque correct on the front and rear suspension mountings. If you remove the front clamshell and bounce the front end, it would return smartly. If you are using the original type of mentalistic bushings, the most important thing is to not over tighten them. 5~7 ft/lb is all you need. Use a fresh Nylock nut or a castle nut and drill the bolt for a cotter pin. Setting it up properly will eliminate a lot of friction, smooth the ride and allow the bushings to last a very long time.

With the mentalistic bushing, the rubber is supposed to take the rotational movement, but it cannot. It shears within a few miles. Use lower torque so that the bolt rotates within the bushing, and the suspension will work much better (and a lot longer. My front bushings are now over a decade old, and are still in good shape). These old style mentalistic bushings are really meant for vibration isolating engine mounts where vibration is to be absorbed by the elastic element, and not meant to be rotated internally. If the suspension bolt torque is set low, the bolt and suspension component can rotate within the suspension component, the elastic absorbing vibration, but not shearing the elastic due to rotation between the inner sleeve and the outer sleeve.

If you have more than 100 miles on the chassis, check the bushings for tearing and looseness. If you find any, change out the bushings for new ones, or, even better, install a set of the urethane bushings with the center sleeve. These can be torqued, as the suspension component will rotate around the sleeve within the urethane element of the bushing. These will also increase the articulation of the rear 4 link setup, resulting in more predictable handling as the arms will have a small amount of compliance during body roll. This improves predictability at the limit.

You can check the rear bushings by rocking the chassis in 1st gear. If you hear a clunk as you rock the chassis back and forth, and see the nose of the differential housing bobbing up and down more than a quarter inch or so, you have broken, worn bushings and they require replacement.

Measure the ride height first with the car empty. Measure under the axle centerline, under the frame rail, which is where you take your measurement. Off side measurement: 5" Front 7.5" rear... Near side (driver's side)" 5.5~5.75 Front 8" Rear. I took these measurements off of my car a few moments ago.
Then take the same measurements with the driver in the car. The ride height should be equal left to right, at about 5" front and 7~7.5" rear. If necessary, make any adjustments to bring the left to right measurements into equal measurement.
Feel free to do the setup with the body off the car. 'Makes it easier. If you get this ride height setup correct, you will be very close to Zero wedge. 50% weight on the diagonal left front to right rear weight. Provided, of course, that the battery is opposite the driver, next to the rear wheel.

I am pretty sure that this ride height will get you over your local "sleeping policemen". You will be amazed at the new steering geometry that you just installed as well.

Now, about the Protechs... If the ride is stiff at the minimal setting, you have to reset the base adjustment. This is probably best with the damper removed from the car, and is covered in your Protech documentation. You may want to make two base line reduction adjustments, as the car is pretty light, and you have a lot of clicks to play with. You want to get it into a position where your changes are incremental. Start with the front. If you have the damper set properly, at zero adjustment, it may just feel a bit floaty. Then do a two click stiffer adjustment. That should firm it up a bit so you can feel the damper working. If you go another click, it will eventually get a bit jiggly. Back it off one click.
Do the same in the rear AFTER you do the front. Don't adjust both front and rear at the same time. You might want to do this with the body off as it makes adjustment a bit easier. I believe that you can mount the dampers with the adjustments at the top, which helps when you have the body on the car.

One more thing... It is important that the springs are long enough so that you don't have a problem with a too short spring, and require a "helper to keep the spring engaged over the damper and inside the "hat". So far, I have not seen this problem with any of the early or later W11s, and the spring rates as supplied appear to be just about perfect.

Let me know how the new tracking and alignment settings work. Have fun! When you finish this and get control of your W11's chassis, you will be an authority, and have a deep understanding of your car, and the work that you put into it.

[Westfield 129]

And I forgot something...

It is important to set the ride height FIRST as this, combined with the tracking, controls the problem of bump steer.
When properly set up, the lower suspension arms will be parallel to the ground, again. around 5~5.5" ride height, with the driver in the car.

Order of operation: Ride height, camber, tracking.

[Morris]

There's a lot of extra info there, thank you Jan.

It looks like I have some work to do to get the best out of the car. Certainly the tyre pressures I can correct in an instant.

To do it justice I'll need to spend a good amount of time going out, making adjustments, driving some more until I find the best geometry. It would also be useful to find a stretch of road where I know the car will be upset in its current set-up, to be able to assess the results of adjustments made.

Btw, I forgot to mention that I do have the front anti-roll bar fitted, and I've read in past posts the benefit of fitting grease points to the mountings. I can do this quite quickly, but the driving season in the UK is tailing off now so I may leave it to the winter months (as with rotating the shocks by 180 degrees to bring the adjuster knobs to the top).

[Westfield 129]

In order to fix the problem, you will have to toss all of your current settings, and start over, just as though you have a freshly finished assembly.

Resetting the tire pressures won't help with the basic problem of improper tracking (you will be surprised as to how far this is out) and ride height, perhaps anti roll bar asymmetrical bias as well.

Ride height first. If you don't address this first, nothing will work out as the ride height and the location of the steering rack (not adjustable) are the reasons for your bump steer problem, which is exacerbated by the tracking toe out, which causes the lack of caster return. In most situations, the ride height is too low, which in turn puts the tie rods out of position, causing the bump steer problem.

If you do the adjustments as recommended, you won't have to go out, drive and make changes... I have 20 years in these cars (50K miles), and several rebuilds that have centered around the chassis setup, as well as total builds that were turn key ready when backed out of my garage. I made all the mistakes so you don't have to.

You might get some bar bell weights that equal your body weight to put in the seat and floor to set the ride height. With this properly set, you can then fix the tracking problem which will eliminate the bump steer and lack of caster return, while delivering neutral handling. Depending on your tires, there will not be any snap over steer, or excessive understeer. You can also get a buddy about your size to sit there while you take measurements, then reset the coil over collars. You can do the basic ride height setup as per my instructions with the car empty and be pretty close. With your buddy in the car, you can set the tracking. I am sure that "toe plates", flat, straight alloy plates with slots for a pair of tape measures are available in the UK. These are not expensive, and are accurate to set tracking. I use a "smart camber tool", which is an electronic level in a frame that measures camber relative to the floor, which means that you don't have to go to an alignment rack to do your setup.

Don't forget to disconnect the anti roll bar before you set the ride height and tracking. The anti roll bar must be set in a static position with your weight in the driver's seat when the adjustments are completed. If you don't, you will end up with different reactions (left to right) from the suspension, especially when turning.

With the car empty, it won't sit level when you look at it, Don't be tempted to fix this, as your body weight is a large percentage of the car's total weight. If you set the anti roll bar with the car empty, there will be a preload on the suspension which will have an effect on both tracking and wheel rates. The attachment of the anti roll bar is the last thing to do. You can invest in pair of LH threaded rod ends, jam nuts and some turnbuckle stock to ease the adjustment. I cannot stress how much time this will save as you wont have to detach the end links to do a simple adjustment, over and over and over... Note that the anti roll bar can screw up the ride height adjustment, which screws up the tracking, which causes both the lack of caster return and bump steer. You can't just adjust one thing at a time. You have to look at the total mechanical organism. This is the ONLY geometry. that you have. You can't change the geometry, but you can change the setup. This is the only setup that can get you a car with neutral handling, healthy caster return and straight line stability. My car, and the ones that I have built are hands off past 100 mph. Yours will be, too.

I say this so that you can not waste time and sort your W11 all at once, and begin to enjoy it. You can play with the damper adjustments as much as you want, and you will get feedback from the dampers, and not from any other suspension feedback due to improper adjustment.

You will go through the chassis setup as though you just finished the car, starting at "0". You have to change/adjust EVERYTHING at one time, in order. I know that this seems to be counterintuitive, but the problem is that the initial setup has to be correct to start with. If you set everything up as I suggested, you won't have any of the problems that you have described. Driving the car to sort out your problems won't work as the entire setup is out of spec, until you measure and adjust. You will have a Westfield 11 that is working at its optimum setup on the 13" tires. If you are running 15" bias ply race tires, I have only one small change, which is to slightly reduce the negative camber to -1º, to be adjusted further by the use of a tire tread pyrometer, at the track.

Once you start driving the car, with proper suspension settings then you can play with the damper settings, but with your single adjustable dampers, you should get this on the first drive. With this setup, the chassis should be neutral. You can dial a small amount of oversteer with the rear dampers, usually with only one click.

With your driving season ended, do the adjustments, ALL OF THEM, as I suggested, and you will have a new car when spring comes. I know of several W11 owners who tried to sort out the suspension, and got nowhere, as they didn't bother to set tie ride height with the driver's weight in the seat, which meant that they could not set the tracking, which meant that they could not fix the lack of caster return or bump steer. The end result is that they didn't drive the cars much. If you don't set the ride height with the driver's weight in the seat, you won't know how much to cut the tie rods to get the proper amount of toe in, and if you don't do that, you can't fix anything. Most owners don't have any experience in chassis setup, and are lost when it comes to setting up the W11 as the chassis setup is not covered well in the "manual". You need to know what bump steer is, where a lack of caster return comes from, and the results of putting 180 lbs in the driver's seat of an 1100 lb car.

W11s need a bit of fettling, but not much if you have a good quality of assembly. The suspension setup is really the thing that makes the car, and there is not much leeway in the basic setup.

The one thing you really can't correct is the wheel spin off of corners, as the inside rear wheel is unloaded. The front anti roll bar helps a little (very little), but an LSD will feel like 20 more HP. Expensive, but not as expensive as trying to find 20 more HP in your BMC A, which will still just spin the rear wheel out of corners. There is one small thing that you will probably do with the LSD... Adjust the rear dampers a click or so stiffer to shift come cornering force to the rear, as corner entry understeer might be increased slightly (depending on which tires and wheels you have.

None of this is really too time consuming. The adjustments are relatively easy. The results will be surprisingly beneficial.

[Morris]

Well it looks like I have some work to do now, but omy looking forward to seeing what improvements I can make.

Thank you Jan for all your advice.

[jonclancy]

Thanks very much for this excellent input, Jan.

That’s the first chapter of the set-up manual almost completed!

[Westfield 129]

Just because the car is "assembled" doesn't mean that it's actually drivable. It's just a bunch of parts rattling down the road.

Brakes are easy, as is making the engine run. Getting good brake feel requires taper wheel bearings. EZ fix.

Suspension is harder. The real problem is that there is no one in a white coat and a clip board that understands the car, and can do the final inspection before sending it out on the road. WE have to do that. The problem is that with most builders, they are not familiar with what it takes to sort out a chassis. Problems, such as no caster return, instability, twitchy steering, hard ride and in a short time, clunking... all need to be covered. This is often exacerbated by the idea that the shocks have to be adjusted before any work has been done, or the car driven and evaluated. I have set up more than one car with the shocks turn WAY up, and the car way too low. OUCH!

I think that I covered the basic chassis setup for ride height, laden and unladen, which is the master starting point.

From there, camber first, then tracking. Remember RIDE HEIGHT IS FIRST. CAMBER HAS AN EFFECT ON TRACKING, SO SET THAT SECOND.
TRACKING IS SET LAST, CHASSIS LADEN, RIDE HEIGHT AND CAMBER SET. ALL ADJUSTMENTS HAVE TO BE CONFIRMED WITH THE CAR LADEN. If you take the car to a shop, make sure that you are sitting in it, or that it is weighted to your personal mass. Otherwise, the time and money are wasted.
It is surprising how much the tracking changes when the driver gets in. In most cases, the toe out is over 1", which causes all sorts of problems (bump steer, lack of caster return, twitchy handling, instability and toothmarks on the heart). Make sure that you have your cut off tool when you get your buddy to sit in the car for you. You will need it to set the tracking as the tie rods from the Spridget rack will be a little too long.
And then, of course, keep the tire pressures to 20 psi or less. Probably less...

Let me know if you need something formal for the manual.