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MG MGB GT V8 Factory Originals Technical - Halfshafts how strong?

How strong are the stock MGB halfshafts.
Has anyone had trouble with them breaking.
I managed to snap one a couple of years ago and am wondering if I need to change them on a regular basis.



Hi Mark,my planet gears and shaft snapped first! but the halfshafts at the splines(diff end) had a neat 45 degree twist in them,so I think they would of been next.I think a lot depends on how wide/grip of the tyres.
Dave Lowe

I'm told that the later MGB axle orrigiated in some form of light truck or van so is heaps strong. I've had no trouble so far although my engine is a pretty much stock standard 3.9.


Although robust they can be uprated - Try GKN or Jack Knight.


I forgot to mention that Im also using a quafe ATB diff. Presumably this helps spread power between the two shafts.
When I have time I think Ill pull the shafts to see if there is any twisting.
Ill look in to uprated ones.


A friend broke one in his 4-cylinder car, which made me wonder about my V8 which are the same, but that is the only failure I have heard of before this.
Paul Hunt


I would suggest that a limited slip dif would increase the torque transferable to a helf shaft.

On a standard dif power can only be trasnmitted when both wheels are in contact and thus the torque is split to each shaft. With an LSD all the torque can go through a single shaft.

It would appear that shafts in an LSD axle may 'see' twice the max torque that a non LSD axle shaft would experience.

I've just talked myself out of fitting one..


The reason for my concern is that I have just upgraded from 4.0L to 4.6L and there is a very noticeable increase in performance.
With a friend in the passenger seat we tried some 0-60mph runs very crudely with a stopwatch and relying on the speedo being reasonably accurate.
With sticky tyres and a dry road we were getting sub 5 second times.



How did you get on at the rolling road and what sort of numbers did it produce? If its providing sub 5 second 0-60 times it must be pretty healthy.
Assume you have more than just the cart springs holding the axle on to the car.

K.R Jackson

The rolling road went well in respect of carb jetting but time was an issue with other customers waiting and I was really disapointed when I realised that a power run had not been completed. I was told to take the car for a road test and it felt really good, the flat spot was gone completely. It was only when I returned that I realised there were no figures.
I know its only numbers but Id love to know what its making. Guess Ill have to book it in again.
As far a rear axle location is concerned i am using Composite springs with anti tramp bars and a panhard rod plumbed in as well, together with my own rear anti roll bar ( which works really well ).





Which rolling road did you use?


I took my car to Sigma engineering, Gillingham, Dorset. They made a good job of jetting the carb but I wasn't completely happy with their service.
To be honest I have yet to find a really good rolling road.


I am in the process of fitting a Panhard rod. Where on the axel is yours attaced relaitve to the center of the axel vertically? Please tell me about your antiroll bar or is there an archived thread I can look up on this. I am considering installing adjustable antiroll bars front and rear to get the right balance in corners. Where did you buy your anti tramp bars and composite springs?
Good luck with the half-shafts.
c l sorenson

Hi Chris
I made my own Panhard Rod, Anti Tramp bars and rear adjustable anti roll bar and am constantly revising the design using trial and error.
My Panhard rod is fixed at one end via a rubber bush onto a bracket bolted to the strengthened boot floor. At the other end I have welded a small bracket outboard and just above the spring plate with a strengthener across onto the axle strap bolt. A half inch bolt attaches the rod end into a captive nut.
Originally Rod ends were used both sides but I found that they would wear fairly quickly making a lot of noise.
When the cars weight is on the suspension the rod is exactly in line with the centre of the axle.

As far as the rear anti roll bar is concerened I agree with most that the stock rubber bumper car Item is not much good. I decided to run my bar under the battery boxes and then back each side with an adjustable slider connected via 2 small rod ends to a bracket welded to the side of the spring plate. Its a tight fit with the Anti tramp bars and tube shocks. The bar is 5/8" diameter and mounted using stock front setup. With the bar attached the suspension is still very supple.
Front anti roll bar is 7/8" with hard bushes and the setup has a very nice balance.
Bought my Composite springs from the MGOC and have been very pleased with their performance.
I think that getting the back suspension right is the key to superb handling with the MGB.
Just my opinion.
Good luck.


I am intrigued by the composite springs, particularly, flexibility of them.
Compared with the origin springs (roadster), the car is it lowered ?
In the Mini world, my passion is the mini, the true, Mike Baldwin is renowned for this tuning to the rolling road.
I bought jack knight half-shaft, I have a Quaife.

This thread was discussed between 28/01/2005 and 10/02/2005

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