Project "Marginal gains..."
Turbo Mini Forums

Very impressive. I've seen on single seater race cars that they also drill holes in the side of the disc hats to save weight. Another few grams that could be saved....

Thanks Dion,

I know what you mean, I have seen a few cars on here which have done it as well, what you can't tell from the photos is that the 'top hat' part of the disc has been thinned down quite a bit already from standard and I wouldn't risk putting any holes in

Cheers

Very good craftmanship. Have you calculated the twisting force you will have on the brackets/tube for the top arm during braking and acceleration? I must confess I would feel safer if the two arms was fixed to different pipes to prevent this twisting force

www.shag.no

Hi Vegar,

Thank you for your comments

Next to simulating the kinematic geometry the analysis of how the forces which are fed into the frame from the suspension links has been where most of my time has been spent.

I have looked at 0.9g braking, 0,9g cornering and forward acceleration.

I calculated the amount the twist in this tube based on the tube diameter / thickness and length of the tube and material but with some assumptions such as the twists about its centre, the effect of the welding heat on the stiffness / strength of the tube etc...

So yes I have considered this but all relies on my assumptions being somewhere near right. I have always planned to add to this area of the subframe once everything is installed - so many things (Gearbox protrusions, gear linkage, starter motor, steering rack) all get in the way of putting nicely placed tubes from this area back to other stiff areas in the frame.

It all stems from keeping a standard length front end, move the engine forward 40 - 50mm and this area is much easier to resolve, I know of one type of frame manufactured which uses a similar top arm layout and has been used for a number of years. This is an AMT frame



Running the same simulations but using the AMT frame hard points (essentially standard Mini in terms of the way the loads are distributed) for suspension parts I have a good idea of the sort of deflections this frame has as a benchmark.

I have already done some 'ugly bar tests' - to visually see what moves and where - which lead to me adding the lower mount in the middle of the subframe which bolts to the tunnel area

So in summary I agree completely with what you are saying and do plan to add to this area

Cheers

Edited by Aubrey_Boy on 14th Jul, 2017.

Plenty going on, but most recently we have the rack mounts which have been made and subframe mounts tacked to the frame - as per the std car the rack is solid mounted, this is the nearside (passenger) side:



You can just make out a 5mm spacer below the ally rack mounts, this gives me le-way to go up or down with the rack for bumpsteer tuning, by my measurements / reckonings the current position gives near as damn it zero bumpsteer. From this position I can add toe in or toe out with bump depending on how the car behaves, I will have a little bit of bumpsteer tuning with the steering arms if I need to as well.



The cast ally part of the rack body has been turned to give a clean outer diameter for the offside clamp to hold on to.

The nearside clamp is as near to the end of the rack body to give more clearance to the diff casing, but enough for the steering gaitor to clamp to once a slight return has been added to the edge of the tube



The rack is now lighter than the original Mini rack having saved a little more weight in a few areas



Going to check the actual bumpsteer and set castor etc... this weekend before I get the rack mounts fully welded as they are just tacked for now

After this the main job is to try and get the wheel rate behaviour with wheel travel that I want which is proving to be the most difficult job so far as the coilover position doesn't lend itself to helping





Rack mounts on the subframe will be further / better triangulated / tied in once I am sure there are no further changes

Cheers

Edited by Aubrey_Boy on 14th Jul, 2017.

very nice

I run a supercharger and I don't care the TB is on the wrong side.
VEMS + 12 PSI + Liquid Intercooler = Small Bore FUN!

Nice Clamps

Matthew

I cant remember , did you consider using something like an astra rack with the arms coming form the centre of the rack ,to get minimal arc deflection ?

Edited by robert on 18th Oct, 2017.

Medusa + injection = too much torque for the dyno ..https://youtu.be/qg5o0_tJxYM

Is minimal arc deflection best though?

I thought that was good for a mcpherson set up, but with dual wish bones like the mini you want the inner track rod ends to sit on the line between the inner wishbone pivots (albeit moved inwards by the amount the outer one is moved in by the steering arm)

I bet that makes no sense to anyone but me...

Thanks for the comments guys,

Hi Robert,

No, not considered the long track rod / centre mounted type racks - no experience of them either, for the reasons mentioned by Joe I have chosen the "keeping the inner track rod end centre on the the axis between the upper and lower, inner wishbone pickups - this can give zero bumpsteer if that's what you want.

Which is the reason why I chose to narrow an MGF / R100 steering rack to put the inner track rod joint in this position,

Cheers

Edited by Aubrey_Boy on 28th Nov, 2014.

LIKE!

ah yes thanks chaps I forgot about the mc, thingy.

Medusa + injection = too much torque for the dyno ..https://youtu.be/qg5o0_tJxYM

This is great work mate, all the way from Australia. defiantly quit your day job.

Bill

Thanks again for the comments, hopefully progress will pick up a little now as I have had a few parts come through

Cheers

I wish I had been able to read this before I spent several weeks, on and off, trying to eliminate bump steer on the A35 rack installation. My problem was that the car is so narrow I had to narrow even the Mini rack !

Even now it is a compromise as I did not wish to lower engine and gearbox any more (Rear drive, bell housing in the way of rear mounted rack)

I also wish my rack mounting blocks looked as good as those !

Hi Tadge,

Thank you, yes the clamps turned out nice and are pretty light as well, 120g IIRC.

Rear mounted racks on an inline installation are a PITA, you say you didn't want to lower the engine any more - is the rack mounted above bell housing?

Cheers

Yes, rack mounted on firewall above bell housing.

I had drilled so many alternative mounting points I had to cut out the entire firewall and weld in a replacement once I decided where it could go.

I need to catch up on this build having not been on here much of late but for some real world feedback we've seen some bent rear arms on the amt frames in the past and I have found that that rosejoint in the rear arm limits suspension travel.
I wanted to run my driveshafts more level than they are now, sort out a decent ride height (lower) and get full droop and a few other things where I thought they should be but couldn't due to that rear mount restricting travel. I think I came to the conclusion it needed to be higher (more level with the front arm position) to get there but wussed out at cutting it off and moving it up. I was afraid of destroying whatever geometry had been built in there already.

Rich

On 12th Oct, 2013 Aubrey_Boy said:
Hi Vegar,

Thank you for your comments

Next to simulating the kinematic geometry the analysis of how the forces which are fed into the frame from the suspension links has been where most of my time has been spent.

I have looked at 0.9g braking, 0,9g cornering and forward acceleration. Without question the braking loadcase is the worst for the loads fed into the subframe.

Under braking the lower wishbone has the highest force - but is in the highest stiffness / strength area for the subframe - so not a problem, the upper wishbone still has reasonably high load and as you state will try to twist vertical leg of the subframe.

Yes I calculated the amount the twist in this tube based on the tube diameter / thickness and length of the tube and material but with some assumptions such as the twists about its centre, the effect of the welding heat on the stiffness / strength of the tube etc...

So yes I have considered this but all relies on my assumptions being somewhere near right. I have always planned to add to this area of the subframe once everything is installed - so many things (Gearbox protrusions, gear linkage, starter motor, steering rack) all get in the way of putting nicely placed tubes from this area back to other stiff areas in the frame.

It all stems from keeping a standard length front end, move the engine forward 40 - 50mm and this area is much easier to resolve, I know of one type of frame manufactured which uses a similar top arm layout and has been used for a number of years. This is an AMT frame



Running the same simulations but using the AMT frame hard points (essentially standard Mini in terms of the way the loads are distributed) for suspension parts I have a good idea of the sort of deflections this frame has as a benchmark.

I have already done some 'ugly bar tests' - to visually see what moves and where - which lead to me adding the lower mount in the middle of the subframe which bolts to the tunnel area

So in summary I agree completely with what you are saying and do plan to add to this area

Cheers

Here for the craic..

Supercharged Arden powered

Hi Rich,

Other than having seen photos I am not very familiar with the AMT frame, so I am not entirely sure what the original design reason for the rear joint of the top 'wishbone' being in that axis (I guess to allow the fore / aft position of the UBJ to be adjusted and make the bracketry on the frame more simple?). As you say it immediately makes it a limiting factor on suspension travel and then bending the arm once the joint necks out or makes contact with some part of the frame. I assume it's the threaded part of the rear link in the top arm that bends?

All of these assume that the rod end is in it's dead central 'neutral' position at your chosen ride height - obviously this is not usually the case so you end up with even less travel in one direction.

As far as moving the upper inboard points up, yes it will change a lot of the kinematics, bumpsteer, roll centre, camber change etc...

Interested to see what you end up doing and how it feels, could you change the rear joint to the same orientation as the front joint - I guess as long you are not going to want to change the fore aft position of the UBJ too much - the only draw back I can think of?

Cheers

Edited by Aubrey_Boy on 3rd Dec, 2014.

Thanks for the reply - yes it was the threaded section that bent, on mine as it sits that arm is angled up and the rose joint fouls the upper tab of the support bracket before the joint runs out of movement. I can't see any problems in refabricating the support bracket in the opposite axis, that would solve a lot of problems!

Edited to add - found a recent picture, I fitted longer coilovers to get some travel without the arms binding, and took this picture, space might be tight to re-orientate the bracket but its definitely something to look at.

Edited by Richspec on 21st Nov, 2013.

Here for the craic..

Supercharged Arden powered

Hi Rich,

If it's useful I am happy to try and create a suspension model based on your hard points - but it would require the X,Y,Z coordinates of each joint centre.

It could be that it's essentially standard Mini except for the coilover mounting - some initial measurements would probably confirm this. That way it wouldn't be a mammoth exercise.

That way I could say what happens to the roll centre / bump steer / camber change etc... If you were to try and change the height of the upper arm

Also looking at your photo above I think I can see the witness mark on the rear clevis where the female rod end touches the frame?

Let me know

Cheers

Edited by Aubrey_Boy on 22nd Nov, 2013.

many thanks, I may take you up on the kind offer at some stage. Yes it took some paint off where it was catching, I reshaped the frame with a curve as opposed to the standard rectangular shape to try and gain a few mm, but it was still making contact.

Rich

Here for the craic..

Supercharged Arden powered

So I have decided that I will go for a front mounted unit mounted as far over to the drivers side as possible to give the downpipe a sensible path and still allow some room for a front mounted rad.



Not ideal for side to side weight distribution but limited on options really, the turbo and the integral wastegate both fit behind an unmodified grille

There is plenty of space under the block, it's difficult to make out properly here but there is an aluminium shear panel now which runs underneath the subframe connecting the lower longitudinal legs together, it kicks up at the front like a sump guard - I decided to do this after committing to going turbo to help tie everything together .

The downpipe will be 2.5" and the primaries will be pretty conservative too in keeping with the 250 - 275 hp output level.



The remainder of the sump can be seen above the downpipe and will be fabricated around the space taken by the downpipe whilst trying to leave room for some flow of air between them. Will need to think about where the dipstick is going as the sump will have no depth on this side of the engine anymore.



Stainless manifold flange in place to look at how the transitions can be made from the head face down to the primary diameter, if anything the outlets from the head are a little bit too big for the primary size.



So a bit of experimenting in the shape of the transitions





So a knocking block can be made up to form the finished items around



Hopefully this week and next will see the manifold and DP progressed enough to check assembled in the car before fully welding it up.

Edit: Also I had a complete rethink on the front coilovers as I wasn't happy with how they worked out

Cheers

Edited by Aubrey_Boy on 14th Jul, 2017.

nice block .

Medusa + injection = too much torque for the dyno ..https://youtu.be/qg5o0_tJxYM

Why thank you Robert

So a bit more progress in the manifold department:

Starts with a plain sheet of stainless, I wanted to use 1.6mm (to keep weight down) but my metal artist advised against it in terms of resistance to cracking and being able to support the weight of the turbo alone, so 2.0mm it was:



Ideally the transitions would be shorter with the space restrictions but the attempts at shorter versions just looked too sharp as far as shape change



Transitions all tacked up



The transitions fit inside the the manifold flange and will be welded on both sides, this also removes the step that was originally present to the ports in the head.



And trialled on the head ready to start the primary to collector shapes



Ports 1 and 4 will probably be mocked up first and dictate the primary length that we attempt to get for 2 and 3 within the package space available



Cheers

Edited by Aubrey_Boy on 14th Jul, 2017.