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MG MG Y Type - YB rear axle

I have a YB I am fitting with MGB motor and drive train. I installed MGB leaf springs and an MGB rear axle. A couple issues arose. 1. the MGB leaf springs moved the axle forward about 1" I can solve this with leaf spring adjustment brackets. 2. the springs had to be pulled inward about 3/8" on each side to line up with the MGB spring perch. I am planning to cut the existing perches off and install new custom made perches. My main concern is number 3. Under full load the axle sits right on the top of he chassis rails. I don't think it should sit on the rails but I don't know how high above the rails the axle should be. If I have to make new perches I'll make them to raise the axle or I could install spacers but I don't know how high. Anyone know how high the axle sits above the rails?
Thanks

WJK Kalafut

I am currently doing the same with a YA. At the moment I am trial fitting the B axle to the original springs. We also noticed that the axle was sitting forward an inch. This seemed strange because the distance from the front eye bolt to the axle locating dowel is the same on the B and the YA. But when we checked the YA owners manual there is a diagram of the spring in relaxed and loaded positions and with the spring loaded the length changes by about half the diameter of the front eye - an inch or so. Hopefully this should mean that when the car is sitting normally the axle will be an inch or so further back.

JRB Moyes

JRB
Thanks for the response...I had the car jack stands under the spring taking the load as if it were on it's wheels. The axle is forward and pushes the wheel almost hitting the front of the well. I can correct this. I'm just not sure how high above the chassis rails the axle should be? Did you notice how high the axle was above the rails before you removed the original rear end? or do you know what the measurement from center of wheel to top of wheel well should be? I just don't think it is right that it is sitting directly on the rails.
WJK Kalafut

Hi Bill, I decided to answer your email on this topic here because it is obvious there are others in the same boat.

Bill you need to read the notes on YT3208 again and for JRB's and others benefit look at 3208 in YTs on Parade and click on the link "MBG Engine" in the text. There is a paragraph specifically on the back axle.

You cannot attach the MGB back axle direct to the spings! Yes the axle tube will be hard on the chassis. You need to replace the mounting pedestal on the original Y axle with a large spacer, probably around 50mm depending on the ride height you need to achieve.

I would strongly recommend you don't pull the springs in to fit the MGB spring mounts. You need to cut these off and refit them about 12mm outboard to line up with the springs. I used original YT springs, MGB springs may be to soft for the heavier weight of Y? I also fabricated Panhard Rod and Jackall brackets with my mounts.

When you re-weld on the spring mount plates to the axle tube you will need to check for any distortion in the tube or take great care to keep the tube cool whilst welding. Bolt 2 off minimum metre long straight pieces of steel to the axle tube flanges and measure the distance between the the flanges and the ends of the pieces of steel to see if they are parallel in plan view or maybe a very small amount of equal toein. I think I have read a spec for this somewhere? The side view of the two pieces need to be aligned with each other and not angled apart indicating a twist.

To answer your question about a bottom bump stop, yes there is a small bump stop mounted on top of the chassis between the legs of the axle strap hoops. Because I used telescopic shocks on the rear with only 100mm of travel I had to make axle retaining hoops and bump stops to suit my car. You need to follow Alan Slattery's lead on using Escort MK1 shocks as they have much longer travel to suit a Y.
Cheers
Richard
R A Prior

Hi Richard, glad you have joined in - your article on Y's on parade has been quite helpful during my build.

Bill, I believe the YB is a quite different axle to the YA, so not sure any information/dimensions I could give you could be relied upon. I originally thought to use the MGB springs and move the locations on the chassis to suit. The car weight is a consideration, but I guess extra leaves could be added. Currently I have used some 40mm box drilled centrally on the upper side and offset on the lower side to avoid twisting the springs. The U-bolts have a slight lean, but I only measured a 15mm total difference across the car between the spring to axle dowels on the Y to B, so 7.5mm to each side.

I am using a tube axle - the donor car was a rubber bumper model. For this afternoon's project, I am hoping to make up some card templates for a combined anti roll bar/ shocker location. Haven't yet decided to keep the Panhard rod - possibly overkill with the ARB as well.

Hope you are OK with using your thread as a "meeting place" for sharing ideas (experience in Richard's case).

Jim
JRB Moyes

I used the original Y springs and just made up new pedestals for the axle housing to line up with them--worked out fine-
William Revit

An update to this.

I have now abandoned the MGB axle in favour of an Austin Cambridge A60 one. I obtained one at the weekend having found out that they are the same 38" across the leaf spring centres as the Y.

Fitted it to the chassis and found that the original Y shockers line up with the mounts on the A60 axle. Just need to machine a fitting to attach to the Y link bushes.

A60 has the same 4.5" wheel stud fitting as MGB albeit with a smaller diameter stud, but as the hub bearing is the same part as pre-67 MGB it may just be a case of replacing the wheel studs or at worse the hub or just using different wheel nuts front to rear.

Stock ratio for an A60 is 4.3:1, but again, pre-67 MGB differential fits (my own A55 Mk1 Cambridge already has one).
JRB Moyes

Hi, I placed an MGB rear into my YA1932 20 years ago and without anyone’s help I removed the pedestals, made a pattern to fit over the arch of the B axle at the same height off the original but didn’t include the addition of the Jackall mount.
I am doing the same thing again right now for another car and have just removed the pedestals from the B and have a spare YA axle and going to attempt to remove the pedestals intact , could be slow work , if it fails , I still have my original patterns so will make up new ones but this time include Jackall mounting.
Tomorrow I will remove a wheel. And look in there to see what the space exists to the chassis rails, bump stops are there still.
Clue , I am told welding the new pedestal care needs to be taken , too much heat in any given area over time can twist the axle housing.
Re the wheel arch space and from a previous earlier post I am running 15 inch wires and have no problem there .
Richard , I still have your PDF of the steel plate bracket for doing the telescopic and this time. Want to add this as well to the current effort .
Again , was that 10 Mm plate you used , do you think a slightly thinner steel could be used safely , seems to be more than enough .

I will measure again the axle dowels , but a rough measurement today seemed there was a difference of 5 mm, not easy to measure accurately with diff housing. Making it a curve.
Timely discussion for me again..
Clive
CR Dickinson

Hi Clive,

Is the B axle you are using banjo or tube type?

Regards, Jim
JRB Moyes

It’s a banjo, as is the one am using again.
Had a go at removing the pedestal , too Difficult So wil make new ones.
CR Dickinson

Hi Bill et al, yes my telescopic shocker mounting bracket was 10mm thick for a couple of reasons. Firstly because it is flat plate and not stiffened in any way I Figured I needed 10mm to accommodate or resist too much flexing or fatigue of the metal. There is going to quite a lot of work happening there with the axle going up and down millions of times! The other reason was give the pin or bolt at the top a decent thickness of steel to hang on and not work loose. If I recall my first attempt I welded the bolt head onto the bracket and the bolt snapped, possibly the heat of welding affected the strength of the bolt. Subsequently I used a bolt with a short smooth shank and tensioned the bolt with a nut or maybe a second lock nut. No more breakages and if it did break a much easier fix than a welded bolt!
Cheers
Richard
R A Prior

Clive
I was waiting to see how you got on cutting the Y pedastals off the housing, it gets messy around the panhard and jackall brackets, I gave up on mine and made new as well

willy
William Revit

This thread was discussed between 14/02/2020 and 11/08/2020

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