gearbox "wire"

Standard & modified running gear

gearbox "wire"

Postby Sleeper » Sat Dec 03, 2016 7:11 am

Dear All
Yet another newbie question,having been underneath I noticed a "wire" coming out of the rear of the gearbox and going through the mounting bracket,my first idea was a reversing switch...but no wires,having trawled through the manual (s) there is no mention of this...it seems under tension...my second guess is a tensioner for some kind of detent in the gearbox ?

Anyone?

Thanks
John
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Re: gearbox "wire"

Postby old english white » Sat Dec 03, 2016 8:50 am

Although it is attached to the gearbox, it is listed under "engine" in the parts book as the "engine steady cable". It is there simply to prevent the engine and gearbox moving forward under extreme braking or impact when the engine moving forward could mean the fan touching the radiator - which you wouldn't want to happen!
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Re: gearbox "wire"

Postby Lurch » Sat Dec 03, 2016 9:56 am

The little cable rather amused me when I discovered it, coming from a series land rover background, I would be expecting a nice beefy steel rod !
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Re: gearbox "wire"

Postby Sleeper » Sat Dec 03, 2016 8:12 pm

I heard just the same today,must be made of a Kevlar/Titanium mix if it will hold the engine back under severe braking...

John ;)
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Re: gearbox "wire"

Postby Custard » Sun Dec 04, 2016 12:26 am

I think the MGB has a solid bar, but a cable shouldn't transmit any vibration back into the chassis.

If the cable is properly adjusted it should make the engine mounts last longer too as they are not subjected to the same shear stresses.

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Re: gearbox "wire"

Postby philthehill » Thu Dec 15, 2016 11:08 pm

It is of benefit to increase the size of the three 1/4" bolts securing the front cable flange to the gearbox casing to 5/16" diameter.
The 1/4" bolts have a tendency to pull out of the gearbox casing if hard braking is regularly undertaken.
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Re: gearbox "wire"

Postby Sleeper » Fri Dec 16, 2016 6:48 am

"Hard Braking" :roll: ,I just backed it off the drive the other day and it scared the poo-poo out of me....front disc kit ordered ,painted and ready to fit...

John
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Re: gearbox "wire"

Postby emjay » Fri Dec 16, 2016 3:06 pm

Part of the problem is the 1/4 bolts are fine thread, so a little over torquing can strip the threads.
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Re: gearbox "wire"

Postby philthehill » Fri Dec 16, 2016 6:51 pm

I agree that the basic problem is the fine 1/4" x 20 TPI UNF threads and they not man enough for the job.
BMC were remiss in not specifying the increase in diameter and the use of a UNC thread when the steady cable was introduced (see wksp Man section AA36 for details). The BMC specification just allowed for the use of the three 1/4" UNF bolts already in place.
If you can - drill the gearbox casing and re-tap using 5/16" x 18 TPI UNC threads..
The tapping drill size is 6.6mm.
Just be careful not to go right through the gearbox casing - just deep enough to suit the set screw or even better use 5/16" UNC studs
(note: a stud should be screwed into the material for a depth of 1 1/4" times its diameter as a minimum)
Re-drill the front cable bracket holes to 5/16".
When securing the set screws or studs into the gearbox casing use Loctite lock and seal.
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