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Setting The Geometry


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#1 JonnyAlpha

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Posted 02 January 2020 - 09:01 AM

Hi;

 

As part of my Engine Upgrade I am trying to build up a spare Front Subframe. The Engine is a 1310 and will eventually have a Stage Two Head. 

 

WRT Geometry having read this excellent thread I am going for a -1 Negative Camber on the front.

 

Questions:

 

1. Should I try and source a preset -1.5 Lower Arm or an Adjustable Lower Arm?

 

 

In the Adjustable Lower description on Mini Spares its states "When increasing negative canber ST Abingdon always advised fitting a 3mm plate under the top arm where the bump stop 2A4267 hits to prevent undue strain on the driveshafts."

 

2. What's the general opinion on this, do I need to make up a 3mm plate to put under the Lower Bump Stop?

 

 

Many thanks

 

 

 



#2 unburntfuelinthemorning

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Posted 02 January 2020 - 10:01 AM

Regarding number one;  a 1.5o negative camber arm doesn't necessarily give you 1.5o of negative camber, it gives you 1.5o more negative camber than whatever you have with standard arms.  You also need to make sure the ride height is where you want it to be as on the front changing ride height causes the amount of camber to change.



#3 nicklouse

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Posted 02 January 2020 - 10:20 AM

Yes fit the spacer it stops the lower ball joint being forced to an angle it can’t do.

 

as above the arm only adds to what you have now. So if you have zero and +1 now you would end up with -1.5 and -0.5



#4 DeadSquare

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Posted 02 January 2020 - 12:44 PM

Hi;

 

As part of my Engine Upgrade I am trying to build up a spare Front Subframe. The Engine is a 1310 and will eventually have a Stage Two Head. 

 

WRT Geometry having read this excellent thread I am going for a -1 Negative Camber on the front.

 

Questions:

 

1. Should I try and source a preset -1.5 Lower Arm or an Adjustable Lower Arm?

 

 

In the Adjustable Lower description on Mini Spares its states "When increasing negative canber ST Abingdon always advised fitting a 3mm plate under the top arm where the bump stop 2A4267 hits to prevent undue strain on the driveshafts."

 

2. What's the general opinion on this, do I need to make up a 3mm plate to put under the Lower Bump Stop?

 

 

Many thanks

 

Go for the adjustable arm, and also fit adjustable tie rods.

 

While you are about it, fit Hi-Lo knuckle joints, and to make a perfect job, sit in the car, or load the car with the equivalent body weight that will usually be carried, when the suspension is set up.



#5 JonnyAlpha

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Posted 02 January 2020 - 06:57 PM

Regarding number one;  a 1.5o negative camber arm doesn't necessarily give you 1.5o of negative camber, it gives you 1.5o more negative camber than whatever you have with standard arms.  You also need to make sure the ride height is where you want it to be as on the front changing ride height causes the amount of camber to change.

 

Hmm, there must be a guide somewhere on how to do this, if I were doing it on the existing car setup I guess I start by measuring everything to see where it currently is and starting from there? 

 

Yes fit the spacer it stops the lower ball joint being forced to an angle it can’t do.

 

as above the arm only adds to what you have now. So if you have zero and +1 now you would end up with -1.5 and -0.5

 

Rgr ref the spacer, glad I found that.

See above ref starting point and my response below.

 

 

Hi;

 

As part of my Engine Upgrade I am trying to build up a spare Front Subframe. The Engine is a 1310 and will eventually have a Stage Two Head. 

 

WRT Geometry having read this excellent thread I am going for a -1 Negative Camber on the front.

 

Questions:

 

1. Should I try and source a preset -1.5 Lower Arm or an Adjustable Lower Arm?

 

 

In the Adjustable Lower description on Mini Spares its states "When increasing negative canber ST Abingdon always advised fitting a 3mm plate under the top arm where the bump stop 2A4267 hits to prevent undue strain on the driveshafts."

 

2. What's the general opinion on this, do I need to make up a 3mm plate to put under the Lower Bump Stop?

 

 

Many thanks

 

Go for the adjustable arm, and also fit adjustable tie rods.

 

While you are about it, fit Hi-Lo knuckle joints, and to make a perfect job, sit in the car, or load the car with the equivalent body weight that will usually be carried, when the suspension is set up.

 

 

I already picked up a set of SH Hi Los (Front and Rear) along with some Spax Adjustable Front Shocks. I also have adjustable Heavy Duty Tie Rods on the existing Subframe.

I guess I'll try and get some adjustable Lower Arms to go with the existing Adjustable Tie Rods and Hi Los and once the car is on the ground with the new engine in (as it will be heavier than the 998. I'll start from there?

 

I was planning on building up the Subframe off the car and when I am ready:

 

1. Lift out the old Engine.

2. Drop the old Subframe.

3. Strip / clean / paint the engine bay. 

4. Put the car in the new Subframe.

5. Drop in the new Engine.

6. Setup the Geometry.

 

That's the plan anyway :-)



#6 unburntfuelinthemorning

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Posted 02 January 2020 - 08:24 PM

This'll help a bit.



#7 no66

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Posted 03 January 2020 - 12:15 PM

Sorry for the hijack. "When increasing negative canber ST Abingdon always advised fitting a 3mm plate under the top arm where the bump stop 2A4267 hits to prevent undue strain on the driveshafts."

Could one place the 3mm plate under the rubber bump stop instead of attching the 3mm plate to the arm? (bring bump stop up 3mm)

Neater installation serving the same purpose? 



#8 imack

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Posted 03 January 2020 - 12:21 PM

I fitted a 3mm plate underneath my rebound stops ok.

#9 JonnyAlpha

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Posted 03 January 2020 - 12:37 PM

Sorry for the hijack. "When increasing negative canber ST Abingdon always advised fitting a 3mm plate under the top arm where the bump stop 2A4267 hits to prevent undue strain on the driveshafts."

Could one place the 3mm plate under the rubber bump stop instead of attching the 3mm plate to the arm? (bring bump stop up 3mm)

Neater installation serving the same purpose? 

 

 

I fitted a 3mm plate underneath my rebound stops ok.

 

Something like this at a guess?



#10 DeadSquare

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Posted 03 January 2020 - 12:44 PM

Sorry for the hijack. "When increasing negative canber ST Abingdon always advised fitting a 3mm plate under the top arm where the bump stop 2A4267 hits to prevent undue strain on the driveshafts."

Could one place the 3mm plate under the rubber bump stop instead of attching the 3mm plate to the arm? (bring bump stop up 3mm)

Neater installation serving the same purpose? 

 

 

 

So long as there is enough thread on the bump stop stud, I can see no reason why you should not place a 3mm spacer above the bump stop.

 

This is almost ancient history, but before global worming, the roads sometimes got covered in snow which occasionally was deep enough to touch the bottom of the car.

 

As a temporary way of raising the car, I used to fix a 32mm section of wood to the top arm with a jubilee clip, to make contact with the bump stop. 



#11 GraemeC

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Posted 03 January 2020 - 12:55 PM

 

Sorry for the hijack. "When increasing negative canber ST Abingdon always advised fitting a 3mm plate under the top arm where the bump stop 2A4267 hits to prevent undue strain on the driveshafts."

Could one place the 3mm plate under the rubber bump stop instead of attching the 3mm plate to the arm? (bring bump stop up 3mm)

Neater installation serving the same purpose? 

 

 

I fitted a 3mm plate underneath my rebound stops ok.

 

Something like this at a guess?

 

 

Wrong bump stop - which also goes for DeadSquare's comment

The rebound buffer, the one the top arm sits against when the suspension is at full droop, is the one in question.

You can fit the 3mm plate under it, but you may need to slot the hole that the screw goes through.  Some already have a slotted hole.

 

I seem to recall somewhere selling thicker rebound buffers.  I also have a hazy memory they were polyurethane - this is one of the few applications where poly doesn't matter (unlike bushes etc).



#12 DeadSquare

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Posted 03 January 2020 - 01:05 PM

 

 

Sorry for the hijack. "When increasing negative canber ST Abingdon always advised fitting a 3mm plate under the top arm where the bump stop 2A4267 hits to prevent undue strain on the driveshafts."

Could one place the 3mm plate under the rubber bump stop instead of attching the 3mm plate to the arm? (bring bump stop up 3mm)

Neater installation serving the same purpose? 

 

 

I fitted a 3mm plate underneath my rebound stops ok.

 

Something like this at a guess?

 

 

Wrong bump stop - which also goes for DeadSquare's comment

The rebound buffer, the one the top arm sits against when the suspension is at full droop, is the one in question.

You can fit the 3mm plate under it, but you may need to slot the hole that the screw goes through.  Some already have a slotted hole.

 

I seem to recall somewhere selling thicker rebound buffers.  I also have a hazy memory they were polyurethane - this is one of the few applications where poly doesn't matter (unlike bushes etc).

 

 

I'm glad that you sorted that out, thank you.



#13 no66

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Posted 03 January 2020 - 07:00 PM

Had me a tad confused, but yes, elongate the slot and fit a plate under. Will do this when i get round to it 



#14 JonnyAlpha

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Posted 04 January 2020 - 09:41 AM

DOH! Yes of course, it’s the bump stop that the Upper Arm rests on :-)

#15 unburntfuelinthemorning

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Posted 04 January 2020 - 10:10 AM

DOH! Yes of course, it’s the bump stop that the Upper Arm rests on :-)

Except it's not a bump stop it's a rebound rubber.  Bump is when the wheel moves up into the wheel arch and rebound is the opposite hence bump stop and rebound stop/rubber.






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