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Front wheel hub E-clip modification.

February 18, 2009 by  
Filed under Tutorials

E-clip Modification to front wheel hub

Tutorial donated by: http://formulabaja.com/

Under certain running conditions, when excessive force is placed upon the front wheel, eg impacts from extreme landings, cornering etc, the e-clip will tend to ‘pop’ off, releasing the front wheel with hub intact (diagram 1 shows stock e-clip connection).

The e-clip connection is the ‘weak’ link, designed to reduce stress on other, potentially more vital or expensive parts, in the event of an impact.

Over time, being aluminium, the hub retaining lip (pic A) will eventually become damaged and worn (as a result of the steel e-clip), to the point that it may not be able to securely retain the e-clip, resulting in the wheel being released with only the slightest of knocks.

Additionally, the e-clip will tend to gradually bow (pic D & diagram 1) after successive runs / impacts, and may go undetected (particularly if any impacts are not sufficient enough to cause the wheel to be released). This can then also result in wheel loss after a light knock. It is therefore important that the e-clips are regularly checked and replaced as necessary as part of a general maintenance routine. Good quality spring steel e-clips will improve the situation.

With the understanding of the reasons behind such a connection, an informed decision can be made whether or not to modify the connection, and the potential risks associated.

For various reasons, other than those mentioned above, the stock e-clip connection may not be desirable – for example – the need for reassurance that the wheel will stay on under race conditions, to prevent damage to front brake callipers & rotors or billet hub carriers that would have otherwise occurred on wheel loss etc. – or for the simple reason not to forever have to chase wheels and replace e-clips or lost wheel bearings.

The following are just two of the numerous options of this simple modification that can be carried out to prevent wheel loss.

NB It is understood that by carrying out these mods, and under specific driving conditions, stress will almost certainly be transferred to other parts and connections, and may potentially result in their failure.

Option1 (pic 2, above) – shows an M5 thread tapped into the existing hub hole, following the removal of the projecting retaining lip (pic A, below)
The above pictures can be used to illustrate both options 1 & 2.

It is important to first check the clearance available between retaining lip and the edge of the ball joint. This dim will vary, and will be instrumental in choosing how to proceed and what fixings will be most suitable.

In this example the final projection from the face of the inner bearing, including washer,  plus screw head (countersunk, button head or otherwise), could not exceed the original retaining lip projection.

Whatever option and fixing method is chosen,  it is recommended to check for free movement while using the radio to turn steering at full lock, left and right, simultaneously moving the suspension through its full motion. Aftermarket (billet) front arms* will have different tolerances to those of the stock plastic arms.  Some grinding to the ball joint or further modification to the screw / washer assembly may be required.

The use of circlips / washers can provide a good midway solution, providing a stronger hub connection, but with ‘release’ in extreme conditions (see further reading).

(*If an alloy aftermarket arm is used, It is worth researching that that particular arm has sufficient clearance for full operational movement prior to any e-clip modification)

Pic H – custom aluminium countersunk washers courtesy – Skaa63

Further Reading –
HPIBajaForum thread

Front Hex Improvement – Karg

HELP!! can’t do eclip mod!!Scoobysting

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