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MG Midget and Sprite Technical - Suspension Mods

Just finished fitting fast road polly bushes on my 1500 front and rear so yet to see how it improves handling , considering fitting ¾” roll bar and maybe lowering by 1” front and back at a later date, so is it worth strengthening the roll bar mounting while I have the engine out ,and will drilling through the chassis rail and bolting through a steel plate on top of rail to sandwich rail between the top and bottom plate be sufficient .
mark 1500 on the road Preston Lancs

Only have a standard one of my 1275 but there have been many horror pictures on here of roll bar mountings being 'liberated' from the chassis, so yes it is a good idea to strengthen especially if you're increasing the size of the bar.
Have a look here for several bits and pieces
http://www.petermayengineering.co.uk/catalogue1.htm#1.9
Jeremy Tickle

Mark bolting through is a good idea but I would make the top holes you drill bigger to allow you to put a piece of steel tube through the chassis rail and weld it in place this will stop you crushing the chassis rails when you tighten the bolts up.
Dave Pratt

i was thinking of putting a 2mm stainless steel plate on top covering the full width to spread the load and the sides of the rail should stop it crushing.
mark 1500 on the road Preston Lancs

I have had the ARB mounts pulled off twice so I really recommend it being reinforced in one way or another. I've had some heavy plate (professionally) welded on the bottom of the chassis rails so I hope that is the last time it needs to be done.
Chris Hasluck

I linked mine to the towing eye with a larger bracket (big chunk of angle steel), then bolted the ARB mount to that. Seems OK so far.
Rob Armstrong

Mark

My plan is to do the same as you, plus screw thur the captive nuts (going the opposite direction) so no play can be introduced thur the chassis rails

Prop
Prop and the Blackhole Midget

Mark,
If you go through and through weld in tubes to take the load.
A plate on top will eventually get pulled down
Onno K

Yes, definitely reinforce it. We did so at the bottom, double skinning over the underneath of the mounting block, so converting the original mounting into what is effectively a truss. (see photo)

It has done a decade of hard graft and competition and no problems.

We contemplated through-bolts, but by the time crush tubes (essential) are welded in and captive nuts put in place so that removal and refitting wouldn't be a hassle we thought this was simpler.


Paul Walbran

The main thing with any reinforcement of this area is the get the ARB loads out to the sides of the box section as they are the bits that have the greatest strength in bending. If you go through to the top and even with anti crush tubes you still have the upper and lower surface which can flex so you would want to sandwich them with a thicker plates top and bottom to transfer the loads to the sides. Potentially a good way is to remove the lower surface and weld in a thicker panel in about 5mm or 6mm between the box section sides and weld the edges to the sides and weld the ARB tapped plate back to that. If done tidily it'll look standard. I did this sort of mod on a mates Austin Sprite with a 7/8" ARB courtesy of the previous owner who had worked for Stothert and Pitt. With a 7/8" ARB I have wondered about what twisted more the ARB or the front chassis. It worked for the owner so that is what matters.
David Billington

I am starting to think the angle iron to the tow eye bolts is a good idea, i will have to get my father in law to look at it when he comes at christmas as he is an ex aircraft stress man
mark 1500 on the road Preston Lancs

there's some pics somewhere in a thread titled "Adjustable Anti Roll Bar". The brackets are strong enough to jack the car up on. If you can't find it I can take some more tomorrow
Rob Armstrong

Thanks had a look at pics and that is what i was thinking of but using original mounts under angle to mount the ARB, did lowering make a big difference
mark 1500 on the road Preston Lancs

yeah, that'd work. I moved mine anyway as the 'chassis rails' are twisted in front of the wishbones on my car.
Rob Armstrong

might be a bit overkill but it cost now't , pulled the mount staight as it was sligtly twisted i cant believe they did not just put a plate across the whole rail when it was new .

mark 1500 on the road Preston Lancs

Hey mark

What are we looking at in the photo...I see the angle iron?

Prop
Prop and the Blackhole Midget

a bit of a better picture arb mount or swaybar

mark 1500 on the road Preston Lancs

great stuff. Looks plenty strong enough, that's not gonna pull out. Pretty much like mine, but you've used even stronger stuff! well done.
Rob Armstrong

Paul

I always struggle to see what you did from your picture - is it two long pieces of steel either side of the ARB mount and two filler strips fore and aft of the ARB mount?

Cheers

Nick
Nick P

no just a 50mm x 50mm x 6mm angle mounted on the tow eye mounts and bolted to the ARB bracket back bolts in the lower side will take the ARB mount second picture shows it better. I was supprised even with a standard ARB on it had started to twist I think they never uprated the mount when they changed the ARB for the 1500.
mark 1500 on the road Preston Lancs

Mark
I believe you are thinking of something like this. The bracket are bolted through the tow eye mounts. Mine is on top the chassis but works also when hanging below the chassis.
Ian

Ian Webb '73 GAN5

no this is it onside fitted

mark 1500 on the road Preston Lancs

Yes that's very similar to mine, but yours hangs below the chassis rail.

(I wanted to increase ground clearance)

Ian
Ian Webb '73 GAN5

This thread was discussed between 21/11/2014 and 25/11/2014

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