Rear radius arms

Post by **GeorgeHurst** » Wed Oct 14, 2009 7:37 pm

I hope this isn't a stupid question, but are the rear radius arm kits available the same as a rear ARB?

I want to fit the radius arm kit to reduce axle tramp in conjunction with a rear suspension refurb, but am aware that one should fit both front and rear ARBs together, so I don't know if I should be fitting the front ARB at the same time as the rear radius arms.

Can anyone help?

Cheers,
George

Post by **PSL184** » Wed Oct 14, 2009 7:44 pm

No, radius arms and roll bars are different altogether - How much power are you producing to get axle tramp in a Minor???

Post by **GeorgeHurst** » Wed Oct 14, 2009 7:55 pm

I'm not producing very much! Standard 1098cc, perhaps I have got the term 'tramp' wrong - the rear of the car bounces all over the place at the moment... if I hit a pothole for instance it feels like the rear lifts off the ground and lands about 10in to the side of where it took off.

The same happens often when going around corners (and not even when going fast or turning agressively), the rear seems to bounce or 'tramp'(?) across the road.

Would radius arms be a useful mod to fit? And do I indeed have 'tramp'?!

Post by **jonathon** » Wed Oct 14, 2009 7:58 pm

Its easy to get tramp from a std Minor

There are 4 kits available which combat tramping but only 3 that successfully counter both tramp and offer better axle location.
I'd forget roll bars and go for better suspension upgrades. If you still get roll (you won't) then ,opt for a front roll bar.

Post by **PSL184** » Wed Oct 14, 2009 8:00 pm

Axle tramp is usually caused by the axle twisting due to the power being transmitted. Bouncing around corners could be siezed dampers / springs / bushes etc. I would make sure all the standard bits are correct before trying to mask the fault in another way....

Post by **bmcecosse** » Wed Oct 14, 2009 8:05 pm

First step - is the rear suspension sitting on the bump stops ? It needs to have some movement. You can trim ~ 1.5" off the tops of the bumps stops if necessary. If you really DO have axle tramp (which is violent thumping at the rear as you accelerate hard while cornering - or possibly in a straight line if you have immense power) - then fitting 7 leaf Traveller springs helps considerably. Of course - the existing suspension should be checked for good condition (no cracked springs ?) and for good condition bushes in the spring eye and in the shackles. Last step - drain the dampers and refill with SAE 40 oil - at the same time checking the rubber mounts for the connecting arm are in good condition.

Post by **rayofleamington** » Wed Oct 14, 2009 8:07 pm

Some rear anti-tramp kit/s will make the rear axle act like an ARB anyway (depending on the design).

I certainly agree that good suspension upgrades can get the Minor round hard corners without the need for ARBs.

Post by **jonathon** » Wed Oct 14, 2009 8:08 pm

I think you mean that Axle tramp is caused when leaf springs are wound up by the torque developed by a take off. This causes the springs to distort into an 'S' shape the springs try to straighten out again thus causing a tramping effect of the wheels bouncing.
Sound advice re std parts check first. It could be that the tramping is showing up weak leaf springs.
If all parts are found to be okay then yes go for a radius arm kit, backed up with better suspension (not obligatory)

Post by **GeorgeHurst** » Wed Oct 14, 2009 8:13 pm

Yeah that's the plan... to revamp all the rear suspension (new springs etc), fit poly bushes and refill the dampers. I was just curious as I'm reading up on the various things to do to sort out the rear and wasn't sure exactly what the radius arm did.

On the strength of the above I will save the money on the radius arms for now and see if the problem persists, if it does then I'll fit them at a later date.

Thanks all for the comments

George

Post by **PSL184** » Wed Oct 14, 2009 8:52 pm

jonathon wrote:I think you mean that Axle tramp is caused when leaf springs are wound up by the torque developed by a take off. This causes the springs to distort into an 'S' shape the springs try to straighten out again thus causing a tramping effect of the wheels bouncing.

Yes mate - exactly what I meant but I put it into "simples" terms

I did have axle tramp in a standard Minor once but I got rid of that by relocating one rear spring pin into the axle mounting plate - The whole axle was twisted over !!! My standard 948's don't give me any bother at the moment though

Post by **GeorgeHurst** » Wed Oct 14, 2009 9:31 pm

On that note... does anyone know where to get said pin? - referred to as 'Dowel bolt' (Item 76) on the diagram on pages I.2/I.3 of the Workshop manual

I can't seem to find it on parts websites. Any pointers would be great

Post by **bmcecosse** » Wed Oct 14, 2009 9:37 pm

This ?? http://www.morrisminorspares.net/shop_item.php?ID=3142

Post by **bmcecosse** » Wed Oct 14, 2009 9:38 pm

This ?? http://www.morrisminorspares.net/shop_item.php?ID=3142

Or do you mean the bolt that goes down through the centre of the leaf spring pack - and clamps it all together? If so - just use any handy bolt!

Post by **GeorgeHurst** » Wed Oct 14, 2009 9:44 pm

I can't see either link!
But yes, I mean the one that sandwiches the locating plates and the leaf spring pack together, going through the middle of all of them. In that case a handy bolt it is!

Post by **bmcecosse** » Wed Oct 14, 2009 10:22 pm

Links work for me - but they were not to the part you want anyway. Have your through bolts rotted away ?

Post by **GeorgeHurst** » Wed Oct 14, 2009 10:27 pm

I am yet to inspect, but I wanted to get them anyway just incase I found they had when I strip the suspension down.

Fingers crossed I can use the original ones, but I hate having to put a job on hold whilst waiting for parts to be delivered half way through, so I tend to get everything I think I need in advance and then end up with a few spares

Post by **bmcecosse** » Wed Oct 14, 2009 10:31 pm

If buying new springs - seriously consider 7 leaf Traveller springs. If you find you don't like them - you can easily take out the extra leaves to make them 6 or 5 leaf springs!

Post by **GeorgeHurst** » Wed Oct 14, 2009 10:34 pm

I am buying new springs, if I were to fit 7 leaves and not like it, would they be identical to genuine 5 leaves if I took two out? That is to say is it a 'bodge' (with respect!) to take the 2 leaves out?

Post by **bmcecosse** » Wed Oct 14, 2009 10:39 pm

No - just the same. But for 'sporty' motoring you will want the stronger Trav springs - which eliminate axle tramp!

Post by **jonathon** » Wed Oct 14, 2009 10:46 pm

I'd keep with the std 5 leave springs and fit better damping. The best set up for a rwd car is firm front and soft rear. Too firm on the back and the car will be undrivable, induce wheel spin and give a very unsettling/figity ride. This in my opinion goes for all road applications and most track.