Hi Folks,
has anyone got pictures of the Sierra front hubs with mushroom inserts? I believe there are two types (normal and offsite) and am interested to see what the differences are.

Thanks,
Donny

Don't have a pic but basically one has the hole in the centre and the other has a hole off centre which allows some adjustment of castor/camber (althought he effects have been debated at length on here before).

Thanks,
I've been looking through the photo archives. This started because I thought the front end of the locost was angled to accomodate the radiator (d'oh). However I've bought some good books recommended here and am working my way through the steering geometry. The castor/camber threads are very informative too.

Found a picture. It's in my archive. It's the only one in my archive!

Moving the insert around doesn't affect castor. It changes trail or lead.

Hole to the front, and the axle trails, like a supermarket trolley.

Hole to the back, ...well, just don't go there.

Hole outside, changes camber negatively.

Hole inside, changes camber positively.

Edit...Add> KPI is the angle between the lateral vertical and the line between the upper and lower balljoint centres. Moving the mushroom around will not affect this.

[Edited on 30/11/05 by Syd Bridge]

I think I'm right in saying it also affects the scrub radius and your KPI (king pin inclination).

So there is quite alot to think about with the inserts.

Mike

These mushrooms are a device I've never seen before. How is the ball joint attached to them? Does it just screw in, and if so, what stops it just unscrewing itself?

This is a Sierra front hub with what I suppose must be the offset type

Cheers
David

[Edited on 29/11/05 by Minicooper]

Not the best of pics but for what its worth
Rescued attachment MK Indy build pics017.jpg

and again
Rescued attachment MK Indy build pics 018.jpg

Rescued attachment MK Indy build pics 076.jpg

quote:

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It changes trail or lead.

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No

OK then, what is castor and what is trail.

its been debated before, a search for trail might find the thread.

However, here's my description of it.

Castor is the angle between vertical and the upper and lower pivot points, when viewed from the side. Trail is the distance between the center of the contact patch and the steering axis, when it is extended to the ground. Hence it is 90 degrees from scrub radius.

A shopping trolley has self centering, it has trail but no castor. Conversely, a car could be set up with no trail or scrub and still self centre via castor.

The two are similar but different. How much weight you apply to either is your choice, its just another small aspect of suspension geometry.