Rear of body needs relieving around beam mounting cutouts to clear top of trailing arm when suspension moves, and mounting holes in floor for tubes in centre of rubber bushes need enlarging. In my S3 the holes were the right diameter but spaced slightly wrong
Possible revision of mounting method for rear subframe, E.G. use of new mount plates which utilise the proper rubber mounts and incorporate ride over skids for the underside. (patterns for these mounts are available).
Nearside engine bay panel needs careful fitting or it does not protrude sufficiently to bolt to subframe, also anti-roll bar cut-outs in engine bay panels may need enlarging towards back of vehicle. Not applicable to S3
Extra care required with anti roll bar mounting bolts as these conflict with engine mount brackets.
Some starters foul solenoid on engine mounting bracket, require cut-out in mouting bracket. Not S3?
Depending on position nearside engine mount may knock on oil filter cosworth oil filter is dimensionally smaller. Not S3?
Floorpan needs major relief around gearbox casing cut-out for five speed box , if fitting to welded tunnel, very difficult to fit as gearbox tail cannot rise sufficiently.
Floorplan needs strengthening around gearbox mounting holes. Support fitted to S3
Handbrake cable holes need careful siting at back of the tunnel to avoid sticking handbrake cables. Outer handbrake cable needs shortening if fitted in recommended position.
Pedal box needs major bracing to retain stiffness, on end of spindle on clutch side to front panel, and also top of pedal assembly back to bulkhead, possibly from top front of box to rear bottom diagonally, heavyweight bracketry required here. Pedal box cover provides some bracing.
Clutch cable is invariably too long, so spacers are required for outer cable, these look better at the bellhousing end. Alternatively fit a MK4/MK5 Cortina cable. Also clutch pedal does not travel to its full extent (it butts up against the bulkhead) so it is especially important to make sure there is no slack in the cable. The pedal may not return fully to its home position, this can render the self adjustment mechanism ineffective. Ensure the full scope of movement before finally fitting the pedal box and cable. Granada cable recommended by RHE as this is long enough to clear exhaust manifold.
Brake pipes can run a bit too close to exhaust manifold when using tubular manifold, so make sure there is plenty of clearance remember the engine rocks toward the offside when drive is taken up.
Sump needs modifying for ground clearance or fit RS2000 sump. Apparently a Capri sump is also suitable.
Front suspension bottom mount bolts much too short,top ones too long and invariably the wrong size. Not S3
Brake-Bias valve needs careful siting for forward/aft orientation it is decceleration sensitive NOT pressure sensitive so it needs to be mounted
i) Correctly oriented (fore/aft).
ii) In a position where its horizontal inclination may be varied as centre of gravity and polar moment of inertia differ from Sierra.
N.B. the RHE demonstrator has this fitted in a side to side orientation, this is incorrect, and will affect braking when cornering hard only, not when braking in a straight line. Current advice is not to fit it as the RH is so much lighter there is little chance of locking the back wheels first.
Accelerator pedal needs careful siting/reworking/shortening, it needs to be mounted higher than shown in manual, and may need to hinge in parallel with the top body tub rail to improve spacing between brake pedal and accelerator. The angle of the top part of pedal not ideal, pedal may need straightening, this is acheived by cutting a small quadrant out of the pedal by the bend, straightening the pedal and welding up. May need to drill new hole through support bracket for accelerator cable, and will need to make up a cable stop bracket as well as a pedal mounting bracket.
Cut outs in rear floor panel for fuel tank sender and filler may need mucho enlargement, trial fit tank to find out. Filler neck needs much hacking at the lip to ensure a good fit.(Angle grinder and steady hand required here) Not S3
Remember! drill all holes required in engine bay top rails for coil, brake pipes, loom mounts etc. BEFORE engine is fitted or you won't be able to get the drill in!
Rear floor panel may need bracing across the back for additional stiffness (recommend angle iron, or angle aluminium). The point at which the diff mounts is not strong enough, extra bracing required (box section) .Also brace required from boot floor to back panel (bolt is hidden behind spare wheel). Not S3?
Main front/rear brake pipe needs careful siting, especially for welded in tunnels. Use side box section (i.e. under drivers elbow)
Main Fuel pipe needs careful siting to avoid contact with side box section. Not S3?
Propshaft can be fragile if not run dead level, either lower gearbox in car to obtain a straight run, or fit transit front UJ to prop. It's worth getting this right first time as the prop is a b*st*rd to replace in-situ (especially with fully welded bodies) Not S3? Propshaft has 2 UJs
Specification for prop shaft is available.
The gearbox mount bracket may be mounted under the car by reversing the splined sockets, but it may require spacing. This minimises the nose down stance of the engine and can straighten the propshaft run. Not S3?
Nearside rear wing is higher (by 1") than offside, as far as I know this is prevalent on all cars so don't panic, only a turbot can see both sides at the same time. Not S3?
The steering column support brackets require cut-outs for the column support bar, more on N/S than on O/S. Not S3!
Steering column support bush requires packing because hole in bulkhead is too big. Maybe silicon or plasticard.
Mini/Reliant Robin/Landrover heater is a good proposition.
Utilising the Sierra wiper mechanism, whilst possible, is extremely difficult and the results are unsatisfactory both aesthetically and from an engineering point of view. Wiper mechanism from a BL car (Mini/Allegro etc.) is a much better solution in all respects.
Tabs welded to the front wing support/light brackets allow them to be attached to the front subframe top rail mounts. Not S3
Radiator is heavily shrouded at recommended position, removal of front bulkhead (but NOT top suspension rail) or perforation of same can improve this, but would recommend re-siting radiator to nosecone, and adding kenlowe or equivalent. Retain engine fan for airflow round engine. Not S3?
If radiator is fitted in standard position, mount well forward to clear viscous fan. Remember engine may surge forward up to 1/2" when braking hard.
Clutch cable lunches itself on exhaust manifold, and requires a bracket to hold in clear position.
Diff mounting bolts tend to foul on the tunnel top flanges at the rear of the car, if the tunnel is already fitted, take care when drilling, if not, slight bias of tunnel top either to nearside or offside should allow clearance. Not S3
When using the standard rear Sierra shock absorbers their excessive length means the tops need to be mounted so far back that they work non-tangentially, almost like a cantilever, pivoting rather than compressing. A better arrangement can be had by using Capri rear shock absorbers and fabricating some simple turret style mounts (patterns available) for the top which bolt to the rear body sides. This is a very simple and effective solution. Not S3
(shocker SPAX part no 447EM).
Coilovers( Spax part nos G221 or G843) can also be used to replace spring/shocker at the rear, but ensure that the top mounts are properly braced and fixed to the body side AND floor panel.
Rear suspension bracket fitted to some S3s has a box section welded on to cope with shorter coilovers. This should be offset to the body (but is not on some brackets). This offset causes the bracket to flex the body which will quickly fatigue it. Needs a bolt through the box section to the side body with a spacer to prevent movement.
ADDENDA following many road miles
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Body tub rear section will machete its way through rubber boots on rear drive shafts when suspension bottoms, the ears of metal on the back of the top rail need to be hacked at to obtain plenty of clearance (illustration available). Not S3
Fuel pick-up hole in tank is too large and will allow rubber seal to slip in/out of joint so use a new gasket cut from sheet rubber is required, an old car inner tube will do niceley. Also welded in bolts for fixing fuel pick up are very fragile; do not overtighten and ensure that all four are tightened down evenly together. ADDENDA, seal from used Pinto oil filter makes an ideal sender/pick-up sealing ring. Not S3?
Fuel filler neck needs to be adequately shortened so that it does not protrude more than .5 inch into the tank, or it will not be possible to completely fill the tank, an airlock will form above the filler neck line. This makes for very short range between fill ups.
Beware the low sump, it is VERY easy to clobber this on raised ironwork,speed humps etc. Proper solution is Cosworth/RS2000 sump and pick up pipe, alternatively, cut and shut the sump and modify the pick up pipe, remember a cut and shut sump will hold less oil and may make the engine more vulnerable to oil surge when cornering/braking.
To solve this baffle the sump with a horizontal (not vertical) baffle. When fitting the RS2000 sump, it may be necessary to relieve the nearside engine bay floor panel to clear the sump directly under the oil-pump area., this will affect the stiffness of the bay panel as part of the 'return' is removed. The stiffness can be re-introduced by bolting some U channel along the length of the engine bay bottom panel (I used a piece of dexion).
The Loom is vulnerable when tucked under the top engine bay chassis rails. As these are plasma cut they are serrated, any wires coming from this area to the engine or ancilliaries can become abraded very quickly as the engine usually rocks a fair bit. Most vulnerable is the alternator line. Do ensure plenty of slack and clearance.
The sidelights can pose a problem, a particularly neat solution is to connect the sidelight circuit to the dipped beam via a 4ohm 25 watt resistor, this will give a very reasonable side-light without cutting the headlamp shell or having to squeeze in an extra bulb. Not S3 headlights - use mini sealed beam connector with sidelight bulb holder built in.
Spare wheel carrier can hole the tank where the bracket fits under the back of the car, a generous piece of aluminium sheet should stop this happening Better solution is to reposition the spare wheel carrier to lie below the tank on the S3.
The Rear body tub cut-outs at the rear sometimes foul on the trailing arms when the suspension bottoms, this can cut though the brake pipe which is mounted at the rear of the trailing arm be VERY careful to check clearance, cutting half an inch from the body tub side should give clearance Not S3 - I have checked this carefully on mine and can't see any possibility of it happening.
