MGB Rear Axle Offset!!

tetlow · Post by **tetlow** » Sun May 27, 2007 5:35 pm

I have just noticed that one of my rear tyres on my MGB is hitting the inner wing when going over a bump.
If I measure between the tyre and arch I get about 1/2" one side and at least 1 1/2" the other. The axle is not sitting in the centre of the car.
I have fitted new springs some time ago and have also fitted Spax Shocks instead of the lever arm units. I have also lowered the axle 1".
I believe the rear axle is only located on the springs.
What can I do please?

Would one solution would be to swap the springs over to hopefully get the axle better centered.
I am not happy with the new shocks so I might replace with the original leverarms which I believe help sideways location of the axle.
Any help would be appreciated.

Dave

ian.stewart · Post by **ian.stewart** » Sun May 27, 2007 7:18 pm

Could be the proverbial can of worms here, meaning there could have been all sorts of reasons for this, it sounds a bit too much for assembly tollerances in the body, the first thing I would do would check the distance from the outer wing to the chassis rail on both sides, if it is the same you have to go to the next thing, and check to see if the springs sit straight and parrell to the chassis rails, another check is measure the spring perch to brake back plate,
Of course its a MBG, and they are not that well known for being the most rust free car in the world, and you could at worst be suffering from somebodys bad repairs in the past
Ian

davemgb · Post by **davemgb** » Mon May 28, 2007 11:48 am

It's not unknown for the springs to twist in their mountings or for the leaves to shift about a bit ( yes I know that sounds horrible !! )

I suggest you jack up the car and support it under the front spring mounts, then loosen the rear shackle nuts and the u-bolt nuts - but don't remove them !!

Now try pushing the axle side to side until the arch clearances are equal then progessively tighten the u-bolt and shackle nuts to about 15 lbft - important here not to turn any one nut more than 1 turn at a time.

Finally lower the car back onto its wheels before torqueing up the nuts, again not turning any nut more than one turn.

The shockers make no difference to lateral location, particularly the lever units which have a spherical joint at the top of the drop link.

Dave

tetlow · Post by **tetlow** » Mon May 28, 2007 1:43 pm

Hi Dave.
Thanks for the tips.

I am going to remove the new tube shocks I fitted a few months ago and will re-fit the standard lever arms. I have had problems with the shocks as they do not have enough travel, even though they are designed for all MGB varaitions

I have had the axle rebuilt with a quaife Diff so it would not supprise me if I have not fitted it correctly. I did the nuts up 5 or more turns at a time.

Regards
Dave

mgbv8 · Post by **mgbv8** » Mon May 28, 2007 6:44 pm

Dave & Dave
All MGB's seem to have the axle offset. No one has really come up with the reason why, but they all have it to some degree.
A lot of folk in the MGB world end up removing the lip from inside the wheel arch when they go up to say 185 tyres to prevent rubbing.
A lot of folk in the MG world say they think it is a body fit problem and that the axle is actually centred on the chassis.
I have cut the little prop cover off mine ( the ribbed bit at the rear of the tunnel) to get the 3" prop in for my TH350. And I can see the prop is deffo nearer the drivers side of the tunnel on mine. My offset is 5/8". But she does run true on the drag strip despite this.
Mine is an original car with no rot or repairs to the rear end at all. It has new standard V8 spec rear springs and lever arm dampers, plus blue bushes all round. My rear springs dont have any sideways movement either.
I followed the same procedure for fitting the rear sprins as Davemgb and it made no difference.
My offset is easy to see when I have my BFG's on for racing. The tyres are only 22" diameter and 10" wide so you can stand and look down each side of the car and see a bit of wall one side and you can see tread on the drivers side.

There have been many discussions on the MGOC forum about this over the years.

If I wanted to get this fixed I would tsake my axle to Geoff Hauser and get him to move the mounting plates, which he will do for not much money.

But I'm quite happy doing with mine for now. I wont bother having my axle modified as I'm still trying to find the upper HP limit of the V8 axle. Once I have found this, it will be an axle change to something stronger that will be made to fit.

davemgb · Post by **davemgb** » Thu May 31, 2007 7:26 pm

In my experience ( ymmv ) MGB back axles don't sit centrally in the tunnel but are always offset to the passenger side so the propshaft clears the handbrake, the fit in the rear arches can usually be tweaked when tightening the ubolts and shackles. Doing one side up completely first always results in the axle being offset in the arches.

I'm happily running 195 tyres with just an occasional rub but I have done a couple of things to the rear suspension to improve the lateral restraint!

Regards,

Dave

mgbv8 · Post by **mgbv8** » Thu May 31, 2007 9:09 pm

Funny you should say that Dave. When I fitted the fatter 3" prop, it rubbed on the handbrake lever pivot nut when I lanched off the line, or when I had a passenger in the car and went over a bump. I had to shave around 3mm off it to stop the annoying rub.
I'll post a thread on the MGOC forum to ask the guys to have a measure of their offsets and see what sort of figures we come up with. Should be an interesting read. For us MG boys anyway.
What MGB do you have Dave? Do you ever take it to track days? I'm holding the MG Drag Racing Club's annual day out at the Pod on 7th July if you want to meet other like minded tuners. As you can imagine, the words Drag Racing, and MGB's are not seen very often. Which is why the club only has a few members, and I really must update the website soon.
I have pit parking reserved for our day out at the Retro show if you want to get a pit pass. Even if you dont want to run the car, you can park up with us lot. Most of the guys just run their 1800's. Where are you based?

mgbv8 · Post by **mgbv8** » Wed Jun 13, 2007 8:50 pm

Sorry chaps!!
I must be having a senior moment. My offset on the MGB is to the passenger side. Dont know why I said the drivers side. Must be because I have been driving a yank tank for a while now.

tetlow · Post by **tetlow** » Wed Jun 13, 2007 9:19 pm

I was at the MGOC last week and their V8 in the showroom has an offset. The axle is towards the passenger side, the reverse of mine.
I talked to one of the directors there and he recommended slotting one side of the mounting points to move the axle over.

They had also rolled the arch lip to allow clearance.
The axle set up there is non standard heavy duty so it all looks like panel problems to me.
Dave