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Mushroom insert for sierra upright
MBrown - 25/8/19 at 06:41 PM

Hi all, I'm just fitting together the wishbones/mushroom inserts/coilovers/hubs etc to the car and in the book it states the 'mushroom' insert should be with the hole at the front. Can anyone confirm which front they mean? Do they mean towards the front of the car, or the front of the upright (and by this is the front the side closest to the car or the side furthest away from the car)? From pictures it looks like the 'front' is the side of the upright closest to the car (figure 5.3 on page 73) but I have my drag link screwed about 5/6 turns from being fully in and the camber still seems slightly too positive? I wouldn't have thought the normal position from the top link is to be screwed all the way in.

Any help confirming would be perfect, thanks all

voucht - 26/8/19 at 01:30 PM


Definitely towards the front of the car :

Don't forget to secure the mushroom insert with a transversal bolt (like the M6 screw you can see the head of on the back of the upright on the picture above), so you make sure the mushroom won't rotate. I think it is compulsory for your IVA. When the mushroom insert is in place, just drill a 6mm hole in the upright and mushroom. Tap the hole at M6x1,00 thread. Done.

More pictures here

Hope that will help

[Edited on 26/8/19 by voucht]

MBrown - 28/8/19 at 05:43 PM

Brilliant thank you!

baz-R - 19/6/20 at 10:17 AM

book build puts the offset hole is forward (12 o'clock looking down front of the car at the top)

i found that the added "trail" gives you a unpleasant side effect of heavy steering and trying to pull straight under heavy breaking though i did used to hill-climb my car on semi slicks and there sierra upright has a lot of undesirable offset between the top and bottom ball joints giving to much king pin inclination

you can set the holes outwards (R 9 o'clock, L 3 o'clock) and adjust the upper joint out this reduces/improves the effective king pin angle a bit improving grip front end grip in turns and gets rid of any trail.
i find its better and still self centres fine on my car