The steering column, electrical column switches, plastic shroud are generally taken from the ford donor car.
The steering rack can come from the same donor but it is suggested to use a rack from a P100 Sierra pickup (available from Pilgrim and included in starter pack), this rack has the same dimensions and operation but is made slimmer and so can help with space when fitting the engine later on.
The column used comes from a sierra donor vehicle and is used complete, you should retain the column, all switches, wiring and connectors, plastic shroud and wheel (for SVA). The picture below shows a sierra column with the plastic shrouds removed. The location for the U-bolt clamp used to secure the the chassis is labelled.
Cover the length of the column, Cover how to stop the rubber bulkhead bush from falling out all the time etc
The bracket supplied to hold the column in place is a Z-shaped steel plate with holes drilled in at top and bottom. The top is bolted to the chassis scuttle area, the bottom holds a large U-clamp that tightens around the neck of the column and holds it in place. It has been found that this bracket can be a bit too weak and lead to a fail point for SVA at some test centres and can also make the wheel feel not quite solid. To prevent this a simple mod is to weld steel plate strips to the edges to make it more rigid. This is a simple mod if you have a welder. The diagram below shows the bracket with the steel strips in red.
Once added this mod gives the wheel a really nice solid feel and will ensure no SVA fail on this issue.
A common problem with the MkIII Sumo is a lack of steering self centring, this can lead to strange handling as well as failures at SVA if not addressed. The problem does appear to be mainly with Sierra based kits. Self centring and the effects of vehicle geometry are fairly complex, but if the basics are understood and the below information is digested any problems can be easily resolved.
The underlying property of a vehicles geometry that causes self-centring is the caster angle, this is explained well here..
The caster angle on a sumo is mainly achieved from the offset that exists with the ford uprights as well as to some degree with the chassis design.
The sumo kit does not have any easy way of modifying the caster angle as some other kits do by using shims around the suspension mounting points. To increase caster angle can only be achieved by a fairly simple modification to the chassis.
The top wishbone is held in place via a long bolt through a tube welded into the chassis, it increase caster angle the top wishbone needs to be moved backwards, to do this is simply a case of trimming this tube at the front to allow the top wishbone to be moved backwards and packing at the back with washers.
The distance between upper and lower balljoints on a Sierra based car is aroun 26cm. Therefore, moving the upper wishbone back 5mm will give you a 1.1 degree increase in caster angle. In terms of number of washers…
Thick washer (2.5mm) = 0.55 degrees
Thin washer (1.5mm) = 0.33 degrees
For safeties sake, please ensure your caster angle is equal both sides. Check out Complet Kit Car magazines June 2012 edition for my article on how to measure caster angle using household items.
If all you wish to do is make sure they are equal, do the following…
1. Ensure the chassis is level left to right using a laser level or spirit level. The best reference point for this is the rear of the upper wishbone tube.
2. With no springs on, prop up the suspension each side to somewhere near the centre of travel and ensure each side is exactly the same height using a laser level.
3. Check the Camber Angle is equal for both wheels and adjust if necessary.
4. With the steering wheel/rack centred, ensure the toe-in is equal both sides. You can do this with string or a very long straight edge using the rear hubs as a reference. The amount of toe in/out isn't critical, just as long as they are equal when the steering is centred.
5. Turn steering wheel exactly 1-turn to the right and note the Camber Angle for both wheels (OSright & NSright).
6. Turn steering wheel back to centre and then exactly 1-turn to the left and note the Camber Angle for both wheels (OSleft & NSleft).
If your Caster Angle is equal, the following should be true…
OSright - OSleft = NSright - NSleft
If Camber, Tracking and Caster are all spot on, the following will also be true and you deserve a medal or at least a nice cool pint of beer…
OSright = NSleft
NSright = OSleft
Other tips for improving self-centring are:
1. make sure the typre pressures are correct
2. make sure you do not have too much camber on the front wheels, these should be set only slightly off vertical (in at the top of the wheel)
3. reduce the amount of lock available. The sierra rack and especially the P100 rack does give a large amount of lock, this can be reduced by pulling back the rubber gaiters on the steering rack and placing packers (some people use jubilee clips) inside the rack.
4. check the tracking is set accurately. (will try and add a section on this sometime soon)
5. if you are Sierra based make sure you have the taller mushrooms, see Front Suspension Page.
I've not seen any figures regarding the amount of castor needed on a Sumo to provide self-centring, so having got mine through IVA I thought I'd let everyone know what worked for me. If have 225/45-17 tyres on the front and 0.25 degrees of static camber angle. Caster angle was initially 6 degrees and that failed. Increasing it to 8 degrees passed the self centring test.
Bump Steer Mod
The standard Sumo Chassis is delivered with a slight geometry issue that can lead to a condition called "bump steer". The symptoms of this is when the car is being driven and the wheels travel over a bump or sudden dip in the road the wheel can turn and the car can lurch from side to side. To correct this problem is fairly straight forward, especially at the early stages of a build when the chassis is easily worked on. Below is the details of how to carry out a minor modification, (know globally as the "Sidecarbod Fix" ) to the chassis to correct this problem. Plenty of Sumos are driving around without this mod being done quite happily, however, it makes a significant difference to the overall handling and confidence you will have in the car if this bump steer problem is removed.
Bump steer is caused by the geometry of the front suspension causing the front of the wheel to "toe out" as the suspension rises. Here is some more further reading on Bump steer.
The cause of the bumpsteer on a sumo is that the rack is too high compared to the track rod ends. To correct it is quite simple, the chassis mounts which are essentially steel tubes welded into the chassis are cut down.
NOTE: You should carefully check your chassis and take measurements before carrying out this mod and ensure you are using a standard rack, your chassis could be ok already, though if you cut too much off you can always pack it back up with spacers)
The standard (current 2008) chassis is delivered with these tubes with a length of around 110mm - 120mm depending on when you bought the chassis, this should be reduced to 102mm by cutting away an 8mm section from the top of both tubes to lower the rack. The picture below shows the length required.
The 102mm measurement is taken from the bottom flat edge of the chassis rail to the top of the rack mount post. A top to measure this is to take a piece of stiff wire and bend it into a L-shape, push the wire down into the hole and hook it onto the bottom edge, then mark the top of the tube onto the wire, pull it out and measure up from the bend to the mark made.
Once the cut is made, the tops of the tubes should be carefully filed flat and deburred.
You may well find that the bolt supplied by Pilgrim in the pack for mounting the rack is of a length that when the rack is lowered will run out of thread before the rack becomes tight, to solve this you can put washers on the under side of the chassis tube, or as shown below, place spacers under the bolt head but above the rack, it should then tighten.
Important note: when the rack is lowered it will slightly lower the steering column. You need to make sure that the steering column does not foul on anything in its new position, such as exhaust headers. One common area that can cause a problem is the lower universal joint touching the upright box section of the chassis. If this becomes close, a simple solution is to use a broad headed hammer to tap the surface of the box section back a small amount to give clearance. Check the full movement of the steering from lock to lock before driving the car after doing this mod.
Important note: lowering the rack will effect the tracking of the vehicle, if you're still building this won't be a problem as you probably won't have set it up too accurately.
This clever builder has used the piece of chassis tube cut off and simply moved it above the rack to avoid running out of thread on the bolt.
Steering Column Bush
One common problem with the steering is the bush that holds the steering column goes through falls apart. The nylon part and the rubber grommet slip apart and the column becomes loose. Below shows the original parts in place.
From the footwell:
From the Engine bay:
This one has been secured with a jubilee clip on either side but is still not a great solution, also over time the rubber grommet can become warn, particularly if the part was taken from an aged donor and feel a little loose and rattly. An easy and fairly cheap solution to this problem is to fit a pressed steel bearing.
Here is a link to a page written by the Northwest Robin Hood owners club on how to prepare the bearing, its very simple.
Fitting a Steering column bearing
To fit into a Sumo is fairly straight forward. If you do this during the build before the engine/dash etc are fitted it should be very simple indeed, if you leave it as a mod after the car is completed it becomes a little more tricky but only due to access.
First you need to obtain a bearing, the part number is SLFL25, though not all suppliers will recognise this part number.
Suppliers I found are:
The Bearing Boys
A bearing should cost £10-£15 delivered including VAT. Here's one:
As you can see, the housing plates the bearing comes with allow it to move very freely.
This picture shows all the bits of the original ford assembly. The inner nylon part rotates within a rubber seal, its is this seal that can become worn over time.
The first thing to do is it slightly thin down the nylon insert, it needs just about 1mm taken off its diameter, easily done by putting a bolt through it and spinning it in a drill and holding a fine file against it. Try to get it even and test regularly to avoid over doing it. It should fit snugly into the bearing centre.
The nylon insert fitted into the bearing.
The next thing to do is to enlarge the hole in the bulkhead. This needs to go from 40mm to around 57mm.
To help get an accurate hole, you can make a template with a large circle of 57mm and an inner partial circle of 40 as shown.
Then tape this so the inner 40mm circle is aligned to the existing hole, then mark the outer circle with a sharp pencil.
It's then just a case of using a dremel, grinding bit, hand file etc to make the hole larger, this is pretty hard work if you're working in the footwell.
Once the hole is made, you'll need to extra holes to bolt the bearing casing in place. I used bolts that were large and so the square holes on the plates had to be very slightly filed to get them through. Nyloc nuts are good here. The box section welding into the chassis just happens to be almost exactly the right size for the bearing casings. The 2 halves of the casing must be tight together and so have to go the same side of the bulk head, inside or outside is fine.
The final fitted bearing:
When fitting, its best not to tighten the grub screws or the bolts until all the steering shaft and joints are in place as this allows it all to find the correct angle.
User fitting comment: on my slightly older chassis, the 40mm hole from manufacture was very low in its bulkhead plate. Had I made the hole concentric when I enlarged it to 57mm via the template idea above, the bearing retaining plate would not have fitted in the recess on the bulkhead.
I found it useful to use the retaining plate as a template and draw around the inside of it as I needed to remove more metal above the existing hole and very little below.
Worth checking before cutting.
A great mod though and really makes a difference to the feel of the steering!