Hub carrier bolts

What owners have reported

The 2007 owner survey recorded failures on fairly young, low-mileage cars:

All the failures in that thread are rear corners on Turbos. That's a small sample, so don't read it as "NA cars and front corners are safe". Check all four.

One owner whose bolts were replaced with standard parts found them bent again two months later. His conclusion was that the bolts bend gradually and then snap, which fits the "no warning" reports.

The owner whose dealer replaced the bolts under warranty believes they were refitted with standard parts, so a warranty repair wasn't necessarily an upgrade. If a car has had this done, find out what was fitted.

The debate: weak bolts or loose bolts?

At least two specialists (one Lotus, one VX race preparer) told owners they'd never seen a failure on their own cars, and suggested the real cause is bolts that were under-torqued at the factory or after geometry work. Either way the fix is the same: new, higher-grade bolts, correctly torqued, and never reuse old ones after geometry work.

The VX race preparer added some numbers: in over 1,000 VX220s they had seen, only one customer car had suffered a failure, and that car had earlier accident damage. They check the bolts at every service or geometry change, and replace any that have moved or are very hard to undo. That fits the "loose bolts" theory, but it's one workshop's experience, not a survey.

What Lotus did

The VX220 and Speedster are built on the Lotus Elise platform. A post in the thread quotes the following for the Elise S2 with steel uprights. The factory figures for the VX220 and Speedster weren't given, so treat these as the best available guide, not as Vauxhall specifications.

• The original rear hub carrier bolt (M10 × 50) is grade 8.8, torqued to 45 Nm (33 lbf ft).
• In 2004 Lotus issued service bulletin 2004/08, changing the rear bolt to a 10.9 part and a torque of 68 Nm (50 lbf ft), described as "for motorsport use".
• The front bolts stayed at 8.8 and 45 Nm.
• When moving from 8.8 to 10.9, tighten to the higher figure.

So 10.9 is what Lotus chose. One owner fitted much stronger bolts (the post says "12.6", probably meant 12.9) and was warned by another that a harder bolt can be more brittle, so the strongest grade isn't automatically the best choice.

If the bolts were thread-locked

The same post quotes Lotus's procedure for any fixing that relies on thread-locking compound:

1. Check the torque.
2. If it reaches the specified torque without the bolt moving, leave it alone.
3. If the bolt moves, the locking compound has failed. Remove the bolt, clean off the old adhesive with a wire brush and acetone, apply new adhesive, refit and tighten to the specified torque.
4. If a bolt was found loose and the car has been driven like that, renew the bolt and inspect the related parts for hole ovality or wear.

Don't assume a service has covered this. A standard Vauxhall service doesn't include a torque check of the suspension bolts, and one owner reported that an "enhanced service" on his car didn't check them either. On a ramp, with a torque wrench and a visual inspection, the check doesn't take long.

What to do

1. Look for a record first. The service history or previous owner may show the bolts have been done, and with what.
2. Inspect. With the wheel off, check each bolt and nut for signs of movement, such as witness marks, fretting, rust weeping from the joint or a bent shank. Anything suspicious means replace.
3. Replace one bolt at a time where you can, so the carrier stays located. Fit new nyloc nuts.
4. Torque to the figure for the grade you fit (see "What Lotus did" above), and use thread-locking compound where the original was thread-locked.
5. Get the geometry checked afterwards. Disturbing the hub carrier can shift the settings, and these cars are very sensitive to geometry.

Common mistakes

• Don't reuse old bolts after a geometry setup. One of the open questions in the original survey was whether failed cars had had their bolts reused.
• "Uprated" needs to mean a higher tensile grade, not just "new". Ask what grade you're getting. 10.9 is the grade Lotus chose.
• Using the 8.8 torque on 10.9 bolts. Lotus specified a higher figure for the stronger bolt.
• Waiting for a failure. One owner whose rear hub carrier needed replacing had waited three weeks, with no estimate, in 2007.
• Have the geometry checked if the car pulls or tramlines afterwards.