Making sure your wheels only come off when you want them to?
Fixing a wheel to an Esprit, or any car for that matter, should be easy. 5 bolts nice and tight and you're done. Well in real life things are more difficult. Bolts loosen, wheels stick to the hubs, bolts get over tightened and won't come out! Well this is a guide on how to properly fit your wheels to your Esprit. If done correctly and unmolested by back street mechanics you should have no problems removing your wheels when you need to and you won't see one overtaking you down the road. You may think it's simple, but read on and make sure you know what should be done.
Problem: Sticking Wheel
This is a common problem which can be categorised into two areas (1) where the nuts themselves become seized on the threads and/or (2) in many cases the alloy wheels corrode along with the hub, becoming seized on the centre spigot. The main problem causing corrosion is the electrolytic effect of two unlike metals being in contact with each other, combined with water and road matter the worst, of course, being the winter salt.
Fixing the Wheel
Initially, it is important that the hub mounting face of both hub and wheel are completely clean and free from any grease, oil or excessive paint, NB: Under NO circumstances should these faces be coated in 'copper' grease or any other type of grease, this greatly increases the likelihood of wheel loss.
Lotus suggest that a 'Copper' grease is applied to the hub spigot (red arrow below) only to minimise the possibility of the alloy wheel sticking to the hub. They also advise that is important that the wheel bolts do not get contaminated with any grease.
When replacing the wheel, position it carefully, pushing it completely home on the centre spigot, fit all of the fixing nuts screwing them completely home with finger pressure only (if this is not possible, either the threads are insufficiently clean, they are damaged, or they are not sufficiently lubricated). If damage is the culprit, then nuts should be replaced. The nuts should then be progressively tightened in sequence, to approximately half the recommended torque to thoroughly locate the wheel BEFORE lowering the weight of the vehicle onto the wheel.
The tightening sequence on a five stud fixing should be as shown in the picture. Following partial tightening, the vehicle may be lowered, the final tightening should always be carried out with the use of an accurate Torque wrench. The wheel bolt torque (100Nm) is designed for a dry and corrosion free bolt. The addition of any serious lubricant can have an effect on the clamping load on the wheel and the load in the bolt. Using some exotic thread lubricant can lead to much higher clamping loads than specified.
Lotus would always prescribe the use of tightening with a 'Torque Wrench'. Lotus consider the wheel fixing as a safety critical feature on their cars and would always specify the use of Lotus approved wheel bolts that are clean and free from corrosion.
This cannot be emphasised enough; there have been as many wheel loss incidents, which were as a direct result of over-tightening as there have been where the tightening was insufficient. It is vitally important that the nuts are seen to tighten with the application of the final tightening with the Torque wrench, until the 'click' indicating the correct Torque, has been achieved.
There have been numerous accounts of tyre fitters and mechanics running up the nuts using an air wrench (which frequently has already over-tightened the nuts). They have then applied a Torque wrench, which merely 'clicks' without the nuts moving, this effectively misleads the uninitiated into thinking that the correct Torque has been applied. When used in this way, the actual Torque figure is unknown, all that can be verified is that it is greater (sometimes considerably), than that required.
Esprit S1 & S2 - 9 daNm (65 lb.ft)
Esprit S3 to V8 - 10 daNm (74 lb.ft)
The right bolts
Note: there are two lengths of wheelbolt; 25 mm thread length for the single piece S4 type wheels, and 30 mm for the 3-piece wheels fitted to other models. A running change to the non-USA 3-piece wheel enabled it to use the shorter 25 mm bolt. In all cases, the correct bolt may be identified by fitting a bolt into an unmounted wheel; the correct bolt will protrude 20mm from the wheel mounting
Ensure that the correct bolts are fitted.
25 mm bolt: Lotus part number A082G6038F
30 mm bolt: Lotus part number P6913401610AS
Locking Wheel Nuts
Most Esprit owners are keen on their alloys and fit locking wheel nuts to stop the 'locals' from removing them. Locking wheel nuts can cause all sorts of problems. From losing the key, seizing, overtightening and damaging the key. They are nothing but trouble. LEW recommends reducing the torque on each locking wheel nut on each wheel. This will help reduce the likelyhood of it sticking and breaking the key when trying to undo a locking wheel nut that's been overtighten.
Our experience is that only high quality components are used. The lower quality parts tend to be a problem as they distort and that is when the problems begin. The components we recommend all comply with the German TUV requirements. This a very tough standard and takes into account extreme loading which replicates seized bolts and the shock loads to release them. The ones we have tested are Trilock & McGard.