66 replies to this topic

[MontpellierVanMan]

Maybe someone could help with identifying these please ? Shots show LHS from front and back.

 

 

I bought them off Ebay as Mini 8.4 discs (with non-std drilled rotors ?) / hubs / steering-arms / driveshafts, probably 10 years ago, with the intention of using them to disc-brake the van.

 

 

Indeed everything fitted perfectly once I had restored them from A to Z.

 

I have used Hi-Lo cones, plus adjustable tie-bars and adjustable rear lower arms, and was able to get the correct camber and caster without any issues.

 

However, once I started to examine the tracking I realised that whilst I could set it right at any given ride height, it was wildly off as soon as the suspension moved - and I mean WILDLY off.

 

With 6' lengths of 30x30 angle iron bolted to the discs (a very good way of exaggerating toe-in / out for what you might call an "approach" to bump-steer, 6' lengths giving about an 8x magnification of what is happening at the tyre diameter) I was seeing deviations of over 350mm (that's a foot to you !) which equates to about a 45mm change in toe measured at the tyres between full-droop and full-bump.

 

On the road this led to a floating sensation requiring constant steering inputs to keep the car in a straight line

 

I then spent a happy few weeks tweaking the steering arms, swapping the standard ball-joints for decent rose-joints from McGills so I could get the alignment I wanted, and shimming - patiently - their position, until I had ended up with virtually ZERO (2' of arc ?) bump-steer deviation over 120mm of suspension movement from full-droop to full-bump - checked with a cheap laser clamped perpendicularly to the disc, projected 3m away onto a bit of masking tape ..................

 

 

 

 

 

............... here are a few pictures if anyone is interested.

 

HOWEVER, the point of my post is : ARE my hubs actually indeed off a Mini and NOT a Metro, and WHY was the bump-steer so awful ?!

 

I can't find any information anywhere that shows anyone plotting bump-steer scientifically on a Mini, so I've no idea how the standard unmodified car measures up ?

 

Can anyone throw any light on this please ?

Edited by MontpellierVanMan, 11 October 2015 - 08:34 AM.

[nicklouse]

There are not metro. They are mini.

[nicklouse]

Do you have the correct arms for the rack?

[Spider]

Do you have the correct arms for the rack?

 

My first thoughts too

 

Check which arms you have

 

 

and check which rack you have - MKI will have 15 teeth and MKII will have 25 teeth. Or measure the length of the rack, from joint to joint. I don't have the length here in front of me, there's not much difference between them, but enough.

 

I recently went through this exersize and be aware that in standard form, the Mini does have Bump Steer built in to it. I think I started a thread on here actually, but while I could identify it, no one I spoke to could explain why, as it defies logic. I'll also add though that while it is there, the Mini is quite sensitive to altering it in the smallest way eg, fitting MKII Arms with a MKI Rack, I know for fact is very noticeable on the road.

[nicklouse]

That was the picture I was looking for as the arms show do not seem to have the lugs fir the later rack.

[Spider]

That was the picture I was looking for as the arms show do not seem to have the lugs fir the later rack.

 

Ah, the Lugs - they'll give a bum steer (pun intended!), I've got loads of MKI arms here with lugs. Sorry, but they are not a guide, the best ways are to measure or have a known one to compare to

 

 

Also an example of the Lugs not being a guide.

[nicklouse]

mmmm guess what I thought mine had lugs. But just had a look at a picture. No lugs.

My memory is shot.

[nicklouse]

Spider. Which why did the wheel get effected in bump and drop on a standard set up?

Got some bottom balljoint spacers on the way for mine. Could be interesting.

[phil hill]

Spider. Which why did the wheel get effected in bump and drop on a standard set up?
Got some bottom balljoint spacers on the way for mine. Could be interesting.

Nick, which supplier came through for you with the spacers?

Phil.

[nicklouse]

Spider. Which why did the wheel get effected in bump and drop on a standard set up?
Got some bottom balljoint spacers on the way for mine. Could be interesting.

Nick, which supplier came through for you with the spacers?
Phil.

Long story.
But Mondo. Note Gerald has passed the reigns over to Leigh. Took a bit of chasing. mondo will be having a new website up soonish.

[Spider]

Spider. Which why did the wheel get effected in bump and drop on a standard set up?

Got some bottom balljoint spacers on the way for mine. Could be interesting.

 

I'll try to make some time this afternoon to dig that out of the Office PC and get it to you. It's only some loose 'sketches' I did on CAD after plotting where all the pick up point and joint centres are.

Edited by Moke Spider, 08 October 2015 - 02:40 AM.

[MontpellierVanMan]

The steering arms on the "Ebay" set - now apparently confirmed as Mini and not Metro ? - were the same shape/height as the original Van ones, and carry the same serial numbers.

 

However, to be sure, I moved the original Van ones OVER to the "Ebay" set in case there were any imperceptible differences.

 

The reason these arms look like lug-less ones on the two initial pictures is because they have been re-forged and the cones filled and re-drilled to 7/16 to keep all the components at a reasonable size (the oft-used drill-to-1/2" route makes everything rather grotesque, IMHO) and as you can see here the lugs are a useful "expendible" zone for retention during these operations.

 

For What It Is Worth, here are some shots of the modifications ; acknowledgements to K.Calver for pointing me in the right direction.

 

Rose-Joints - freed from the original conical fixing  - make it possible to change the relative height of the track-rod end, and this is the only really practical "variable" that you can do on a Mini to address the bump-steer issue. By shimming underneath the steering-arm-to-hub-interface - initially - to get a rough idea of where you need to go height-wise, the steering arms can be re-shaped so that they are a tad too high, and the rose-joint-to steering-arm-interface can then be shimmed for final adjustments.

 

 

 

 

 

 

 

 

 

 

 

 

Regarding the rack, I replaced the original Van one with FAM7307HR (LHD, France, geddit ?) from Somerford, a brand-new unit, which is listed as MkII onwards ; I didn't compare the exact position of the inner track-rod pivots and threw the original Van one out, which was LHD too, but it seems highly unlikely that the rack geometry would be different - there aren't exactly many variants of this component ?

 

So, yes, I've overcome a problem that I can't understand the origins of.

 

 

Edited by MontpellierVanMan, 11 October 2015 - 08:50 AM.

[nicklouse]

1: why have you done all the above?

2: when have you done the above?

 

i am guessing it was done before the problem in your first post?

[Spider]

Between the MKI and MKII Racks they are different, and technically, not interchangable..

 

The MKII Rack, between the rod end ball joints (that screw on to the rack itself) is, from memory, 10 mm difference in length on each end than the MKI rack.

 

The MKII Steering Set up was introduced to reduce the turning circle.

 

You modifications to the Steering Arms have me curious and could in fact make matters worse.

 

When a Stock Steering Rod End is fitted, the pivot point is (in a MKI set up) on dead centre with the Pivot Centre of the CV Joint and is right between the pivot centres of the Ball Joints (hope that makes sense). A small compromise is made with this on a MKII set up.

 

By the look of your steering arms (before modification) they were MKI Arms. The Rack from Somerford is a MKII design.

Edited by Moke Spider, 08 October 2015 - 10:55 AM.

[MontpellierVanMan]

Seem to have posted twice, sorry, please jump to page 2.

Edited by MontpellierVanMan, 08 October 2015 - 06:17 PM.