Caliper securing bolts

[stuartgb100]

The rear caliper securing bolts on my sprint are fitted with both a plain and spring washer.

Parts manual Section J page 11 figure 6 shows the spring washer.
Section J page 10 item 1 (top of page) says to torque them up and then wire them.

What is this wiring thing?

In the distant past, I remember a kind of 'c' shaped washer on other cars, whereby it was shaped to fit over both holes in the caliper. You bolted up and torqued the retaining bolts and then flattened little tabs against the flats on the bolt heads.

So, am I ok with just spring washers, or .... ?

Regards,

Stuart.

[M100]

The heads on the Lotus supplied bolts were crossdrilled with a hole around 1/16", stainless wire is then used to fasten one bolt to the other in a way that will stop them unscrewing in use. You need special lockwire pliers to do a proper job (they twist the wire much neater than you do by hand)

When using lockwire fit the bolts with just a plain washer. At a push you can just use a medium strength locking compound such as Loctite 242/243. I'd forget the spring washer in both cases.

To drill the hole in bolts it's best to use a special jig







Also see here for the wiring patterns used.

http://www.lrrsracing.com/RuleBook/lockwire.htm

[steveww]

Are the front caliper bolts supposed to be wired also?

You can drill the bolts with out a jig if you have a pillar drill and machine vice.

[john66s3]

The "wiring thing" is safety wiring.

On my 66S3 the caliper bolts are drilled across the head for safety wiring. Safety wiring uses steel wire through the two bolt heads twisted in such a way as to keep the bolts from being able to back out of their threads. There are special pliers made that make this a snap to do. I have the caliper bolts safety wired on my car - but we would have to check with the "experts" to see if it is still deamed a necessary action with modern fastener hardware.

You can get more info on some of the racing sites - IIRC Pegasus Racing has some information.

John
66 S3 DHC

[M100]

I've never seen reference to the fronts being wired. Certainly the bolts originally supplied by Lotus (XUFB 0720) are an off the shelf standard item, in this case Hex head 7/16" UNF 1 1/4" long.

The rears (26J0002) are a "special"

[stuartgb100]

Many thanks for the help.

Looks like first job is to ascertain what type of bolts I've inherited.

Just rebuilt the rear suspension, and in disassembling it, I noticed how 'loose' one or two of the caliper bolts seemed to be. That's what prompted reference to the manual, and my post.

BTW, I knew the principal of locking wire, not this Lotus detail.

Thanks to Martin for the images, and also for the link. When I followed the link and saw all the locking wire diagrams
.............. well, just for a minute I thought I was back in Boy Scout camp trying to learn how to tie knots, again!!

So, my worst case would be a need for new bolts and locking wire.

Presumably locking wire from a local factor. But the bolts?

Regards and thanks,

Stuart.

[steveww]

Interesting that the rear uses lock wire but the front does not

I have drilled the front bolts and wired them. May be I am a bit paranoid

In the UK you can get the lock wire pliers here:
http://www.vehicle-wiring-products.co.u ... ers-2.html

Less expensive the DT.

[rgh0]

I think the difference between front and rear is due to the rear mounting being a Lotus specific design through the relatively thick alloy ears on the hub. Lotus obviously felt the security of all this was potentially problematic and specified lock wiring to ensure no loosening. The fronts were a standard and well proven Triumph design bolting though a much thinner steel plate that had been proven in practice to not require lock wiring and Lotus chose not to change this standard design they adopted..

Rohan

[GrUmPyBoDgEr]

I go along with Rohan.
Steel bolts fitted into aluminium (U.S. aluminum ) are always prone to torque relaxation. Differential thermal expansion & all that stuff; hence the use of locking wire.
Steel bolts into steel or iron do not suffer so dramatically from these effects.
Locking "tab washers" as mentioned previously can be used to achieve the same result.
Spring washers are very ineffective. A spring washer combined with a plain washer eliminates any effect the spring washer might have had.
John