Whats the Score with adjustable top mounts?

V

vipergts

Well-Known Forum User
Been searching on here with many threads never really concluding

What's the way to go? Need camber and castor adjustment
 
johnymd

johnymd

Club Member
On my blue car I've fitted ground control top camber plate all round to allow me the maximum of adjustment. It will involve cutting the top of you strut towers. You can also get camber and caster adjustment with the kmac mounts and not cut the towers al all.
 
V

vipergts

Well-Known Forum User
johnymd said:
On my blue car I've fitted ground control top camber plate all round to allow me the maximum of adjustment. It will involve cutting the top of you strut towers. You can also get camber and caster adjustment with the kmac mounts and not cut the towers al all.
Click to expand...
Cheers Johny

I like the look of the K-Mac ones. Seems harsh not fitting the big rubber top though but that's what they say
 
atomman

atomman

Club Member
I made some adjustable top mounts for my old Z , because I didn't want to cut or slot the top mounts, The ride was a bit harsh to be honest, I did have stiff springs though,

I ended up using the 25mm offset RCA's / bump steer spacers to give me the required camber and putting the OG rubber top mount back on, ive done the same with my new Z to,

how much camber do you need ?

hope that helps
 
V

vipergts

Well-Known Forum User
atomman said:
I made some adjustable top mounts for my old Z , because I didn't want to cut or slot the top mounts, The ride was a bit harsh to be honest, I did have stiff springs though,

I ended up using the 25mm offset RCA's / bump steer spacers to give me the required camber and putting the OG rubber top mount back on, ive done the same with my new Z to,

how much camber do you need ?

hope that helps
Click to expand...

Not sure but because I had Gaz build me my struts the hubs are all different
 
Alphabettispaghetti

Alphabettispaghetti

Club Member
Sorry about the fudged link

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Alphabettispaghetti

Alphabettispaghetti

Club Member
atomman said:
They look lovely ! How much camber do they give ? but they look like there fixed and not adjustable ? And do you lose the OG rubber top mount ?
Click to expand...

Yes, nicely machined aren't they.

I can't remember off hand, just a tad more caster camber, they are fixed, as they ended up at the best all round solution. I never recall seeing any proper race/rally cars running adjustable tops, they all get altered though?

As above, i was worried about loosing the topmounts, however I've been reassured that you won't be able to tell....... time will tell on that one.
 
Rob Gaskin

Rob Gaskin

Treasurer
Staff member
Site Administrator
Franky, is that spacer for the rear?

When you tighten the front is that top spring-seat up against the spherical bearing and still clear of the top-mount?

You know why I'm asking this probably - all the weight of the car will be taken by the little spherical bearing.
 
Alphabettispaghetti

Alphabettispaghetti

Club Member
Rob Gaskin said:
Franky, is that spacer for the rear?

When you tighten the front is that top spring-seat up against the spherical bearing and still clear of the top-mount?

You know why I'm asking this probably - all the weight of the car will be taken by the little spherical bearing.
Click to expand...


Hi rob, on the top two pics, you can see its fully complete and torqued, the spacer sits on spring 'tophat', which then passes the load to the big spherical bearing in the middle of the topmounts, this provides the clearance and allows the spherical bearing to work properly and move though the suspension travel, you'll know what its like if its not done properly(IIRC). you can see the flat on the spring tophat where the spacer sits.

Yes it takes the weight of the car, these are race and rally proven items though, from a proper motorsport engineer. Have a look at a standard topmount, not much to them at all.
 
atomman

atomman

Club Member
franky said:
Yes, nicely machined aren't they.

I can't remember off hand, just a tad more caster camber, they are fixed, as they ended up at the best all round solution. I never recall seeing any proper race/rally cars running adjustable tops, they all get altered though?

As above, i was worried about loosing the topmounts, however I've been reassured that you won't be able to tell....... time will tell on that one.
Click to expand...

Yes to be honest once I have set the suspension up , I never tend to re-adjust it ,

I'm sure the ride will be ok , depend's how stiff the springs are , what did you go with ?
 
Albrecht

Albrecht

Well-Known Forum User
Rob Gaskin said:
Franky, is that spacer for the rear?

When you tighten the front is that top spring-seat up against the spherical bearing and still clear of the top-mount?

You know why I'm asking this probably - all the weight of the car will be taken by the little spherical bearing.
Click to expand...

That size of spherical bearing is more than capable of handling the loads put through it whilst also allowing the swivel of the strut leg required by the steering, and in fact is better at coping with the slight horizontal twist on the top mount when the suspension is moving between bump/rebound/bump than the stock bearing is.

The later Works race and rally cars had a similar solution, with a spherical bearing in an offset top mount which gave a camber and caster change:

 
Alphabettispaghetti

Alphabettispaghetti

Club Member
Albrecht said:
That size of spherical bearing is more than capable of handling the loads put through it whilst also allowing the swivel of the strut leg required by the steering, and in fact is better at coping with the slight horizontal twist on the top mount when the suspension is moving between bump/rebound/bump than the stock bearing is.

The later Works race and rally cars had a similar solution, with a spherical bearing in an offset top mount which gave a camber and caster change:

Click to expand...

So they are period correct. Well about 25% in purpose.
 
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