Mach 2 mystery revealed

[Tony]

The Mach 2 is an Australian marketed Toyota Soarer... This one is a 2.5L single turbo Tourer V. (rare as hens teeth in the UK)

 

As you will see it has had extensive suspension up-grades and needed calibrating for fast road with occasional track days.

 

The owner contacted a well known Motorsport company who said they could set the car for him if it was left with them for a week?

 

Dismissing this the owner went to another well known company who specialize in setting/calibrating WRX's.... After the Geometry was calibrated the handling was dire, so bad the owner and mechanic decided to call this a bad deal to the extent not even go back to complain or request a refund.

 

After some searching online and in PH the owner came to wim today...... Now i have never seen this type of car before. Hadn't even spoken to the owner online to assess his problem.

 

From a distance before the car was even measured i could see something was very wrong!!

 

For whatever reason the specialist company had set the rear wheels back with obvious displacement in the drive train....

 

 

 

Why! .... The calibration reports from the said company only displayed the secondary angles but had no previous positions available for diagnostics.

 

I measured the Geometry for an overview but no real force was shown to display the handling complaint using my current machine with limited primary and secondary information.

 

Question for Sam@tdi and Jon. Since i cannot measure axial set-back or kinematic toe at the moment. What are your thoughts on this rear chassis alignment...

 

 

 

As you can see we have toe/camber/ trailing arm adjusters available. I assume with the drive train set so far back that the dynamic pneumatics will be horrific..?

 

Your thoughts on this would be very welcome.

 

Note: The owner has been invited to wim to explain his own views. And i have referred the car to tdi-south for some indexing on the Arago machine.

[Sam@TDi]

Blimey this could a be a complete can of worms, to analyse the effects of these changes accurately we would need to replicate the entire rear suspension set-up inside a computer model and manipulate it there.

 

At first glance it seems as though the overall aim has been to lengthen the cars wheel base. That in essence is actually quite a sound idea because these cars suffer from a dynamic index somewhere around 1.50, possibly worse depending on spec. The only question is how has this has impacted the kinematic geometry

[Bazza]

any pics of the car in its full glory

[Talat]

Hi Tony,

 

Was good to meet you today but a pity that you couldn't work your magic on this car. Just to give some background info to pad out your initial post - when the car was bought in Japan it looked like this:

 

http://i120.photobucket.com/albums/o172/JZ...75Mark2left.jpg

 

As you can see the rear wheel looks bent inwards. We were not sure why it was in that state and so assumed that the previous owner crashed the car into a kerb or something and did a quick bodge to get it fairly straight before selling it on. In that state the cars backend felt fairly light and it would wheelspin under moderate power. I decided to uprate the shocks to coilovers and my mechanic managed to get the wheel looking fairly straight - in that guise it handled ok but still had the tendancy to spin the rears at moderate power levels - in hindsight I'm not sure if this was due to poor rubber. Anyhoo, the final phase was to uprate all the bushes and fit adjustable arms etc. At this stage I decided to take it to a specialist alignment place and it now looks like this:

 

http://i120.photobucket.com/albums/o172/JZ...2/jzx100_01.jpg

 

It doesn't look right and more to the point I don't think it handles right. I really need to find someone who can position those rear wheels correctly.

 

As an aside, the car is actually a Toyota Mark 2 and is fairly popular in Australia but is only available as an import as far as I am aware

 

Cheers,

 

Talat.

[Rich]

Nice car, welcome to WIM

 

Hope you get the problem sorted soon

[Noel]

welcome...

 

nice motor, but the rear wheels pushed back like that just looks wrong

 

hope you get it sorted...

[scorps]

Is this set up STD on these cars as it looks quite trick.

 

Oh and welcome to WIM

[Tony]

Blimey this could a be a complete can of worms, to analyse the effects of these changes accurately we would need to replicate the entire rear suspension set-up inside a computer model and manipulate it there.

 

At first glance it seems as though the overall aim has been to lengthen the cars wheel base. That in essence is actually quite a sound idea because these cars suffer from a dynamic index somewhere around 1.50, possibly worse depending on spec. The only question is how has this has impacted the kinematic geometry

 

Wouldn't it have been wiser to corner weight the car rather then just extend the wheel-base and violate the Kinematics? As i said i measured the Geometry positions and the calibration is set to over-steer and although the rear camber/toe is to gentle in my opinion this doesn't account for the handling complaint.

 

Talat's car needs 3D imaging to locate and correct the rear set-back, tdi's Arago can do this with ease. Then you can apply known calibration to compliment the available adjusters fitted to the car, which is global in this case the car is fully adjustable..

Camber front rear

Toe front rear

Set-back front rear

Castor

Coilovers

Toot

Lock angles

 

What do you suggest Sam@tdi.... Corner weight then calibrate the Geometry?

 

Welcome to wim Talat Thank you for the images and explaining the cars identity.

[Sam@TDi]

Corner weighting wouldn't be a good tool on this one as the problems sounds totally goemetry based, the important thing will be to make sure that the rear wheels arn't being pulled into a toe out geometry as the suspension articulates. Actually tracking the geometry as the wheel moves will be very difficult. This will need a very good looking at, and some serious thinking

[Tony]

Corner weighting wouldn't be a good tool on this one as the problems sounds totally goemetry based, the important thing will be to make sure that the rear wheels arn't being pulled into a toe out geometry as the suspension articulates. Actually tracking the geometry as the wheel moves will be very difficult. This will need a very good looking at, and some serious thinking

 

So you agree setting the rear wheels back to extend the wheel base in this case was not wise? I feel this car needs the rear set-back measuring and re-aligning so the drive train is correctly positioned. Then we can work on the Geometry kinematics. What do you think?

[Talat]

Thanks for the welcome Hopefully I can get this problem sorted sooner rather than later as I fancy doing some track days in the not too distant future.

 

Cheers,

 

Talat.

[Sam@TDi]

Actually I think extending the wheelbase is a nice direct solution for a poor DI but it's rarely a viable solution on a production road car because of problems like we're seeing here which the kinematic geometry being wrecked. As I said it's going to need investigating extensively before any possible solutions can be tabled

[Tony]

Thanks for the welcome Hopefully I can get this problem sorted sooner rather than later as I fancy doing some track days in the not too distant future.

 

Cheers,

 

Talat.

The issue is easy to solve with the right equipment. As Sam@tdi says the principle of extending the wheel base is solid assuming there is no consequence. In your case there was! It just seems so odd a professional company would do this and not give you the correct data on the print out or an explanation why.....

 

Apart from some moves in the rear calibration in favor of track days the car is reasonably well set but with the rear so set back the application of thrust to the tyres is saturating them. Hence the complaint.

 

A i said tdi's machine is able to position the rear set-back. Once done the rest of the calibration is simple.

[Talat]

Cheers for the input.

 

The car seems to have developed a misfire and once that gets sorted I shall contact TDI to arrange a time to book the car in.

 

Sam@TDi - do you reckon that it can be fixed in a day or would I have to leave car with you ?

 

Cheers,

 

Talat.

[Sam@TDi]

Hi Talat, to be honest at this point I think it's best to just take a look and see exactly what the problem is and whether there's a straight forward solution. If there is then no prob's, we'll make it happen.

[Mat]

has anyone considered dropping the subframe and looking at the locating points, what does the other side of the car look like in relation.

 

if the other side looks in the right place, can datum points not be taken from the other side to mirror across to this side, with all the adjustable links in there something bordering on similar should be achieved

 

at least this is a starting point.

 

however, there is something drastically wrong for sure!!

 

something id definatley consider, is sourcing at least that's sides standered suspension components, the problem now is that it will take alot of work to try and find even the factory settings.

[Sam@TDi]

it will take alot of work to try and find even the factory settings.

 

My thoughts exactly

[Tony]

has anyone considered dropping the subframe and looking at the locating points, what does the other side of the car look like in relation.

 

if the other side looks in the right place, can datum points not be taken from the other side to mirror across to this side, with all the adjustable links in there something bordering on similar should be achieved

 

at least this is a starting point.

 

however, there is something drastically wrong for sure!!

 

something id definatley consider, is sourcing at least that's sides standered suspension components, the problem now is that it will take alot of work to try and find even the factory settings.

 

The rear adjustable trailing arms are an addition to the car and have been incorrectly set violating the final drive train. All this car needs is the rear set-back measuring then adjusting back to 0 nsr&osr. At the moment the shafts are swept back / \ violating the application of thrust at the tyre.

[Mat]

has anyone considered dropping the subframe and looking at the locating points, what does the other side of the car look like in relation.

 

if the other side looks in the right place, can datum points not be taken from the other side to mirror across to this side, with all the adjustable links in there something bordering on similar should be achieved

 

at least this is a starting point.

 

however, there is something drastically wrong for sure!!

 

something id definatley consider, is sourcing at least that's sides standered suspension components, the problem now is that it will take alot of work to try and find even the factory settings.

 

The rear adjustable trailing arms are an addition to the car and have been incorrectly set violating the final drive train. All this car needs is the rear set-back measuring then adjusting back to 0 nsr&osr. At the moment the shafts are swept back / \ violating the application of thrust at the tyre.

 

 

yep, tony i know the parts are aftermarket.....

 

but there seems to be alot of discussion about this and that and the other, but no visable solution forthcoming, my suggestions were a means to get to the route cause quickly,

 

less talking---------more action

[scorps]

Question...

Is this set up STD on these cars as it looks quite trick.

 

Oh and welcome to WIM

 

At LAST I GOT AN ANSWER....ONLY TOOK 12 REPLIES

 

yep, tony i know the parts are aftermarket.....

less talking---------more action

[Tony]

Ok .... Seemingly i have missed a verse here. In my opinion all this car needs is the rear set-back (imaged) then corrected so the drive train is transversely aligned. Factory positions are irrelevant only the complaint has a voice.

If i were to set this on the Arago then i would 0 the rear set-back..... Set all the other positions to suit the customers requests then test drive the car.

[Talat]

Hi all,

 

Whilst speaking to my mechanic last night, it appears that the subframe had sustained some damage and that is why the wheel was bent inwards when I first took the car to him. He repaired the damage and managed to get the wheel straight. Later on the subframe was dropped to fit some uprated bushes and everything looked ok.

 

I still have all the stock arms and my mechanic has assured me that he can get the wheels back to their previous state. So the initial plan of action is to get the wheels back to their previous state and then start to make adjustments to see if the rear traction can be improved.

 

One other thing that we noticed was that the rear traction arms were replaced with uprated items but these have some play in them and produce a knocking sound - my mechanic thinks that they're possibly defective and so one of the things we'll try is swapping back the stock arms to see if it makes any difference.

 

Cheers,

 

T.

[Tony]

Hi all,

 

Whilst speaking to my mechanic last night, it appears that the subframe had sustained some damage and that is why the wheel was bent inwards when I first took the car to him. He repaired the damage and managed to get the wheel straight. Later on the subframe was dropped to fit some uprated bushes and everything looked ok.

 

I still have all the stock arms and my mechanic has assured me that he can get the wheels back to their previous state. So the initial plan of action is to get the wheels back to their previous state and then start to make adjustments to see if the rear traction can be improved.

 

One other thing that we noticed was that the rear traction arms were replaced with uprated items but these have some play in them and produce a knocking sound - my mechanic thinks that they're possibly defective and so one of the things we'll try is swapping back the stock arms to see if it makes any difference.

 

Cheers,

 

T.

I did wonder is the original arms were available..... Happy days now then mate. All you need to do is measure the location points on the original arms then mimic this on the adjustable trailing arms.... In theory we are re-setting the original wheel base and ready to address the actual calibration.

[Mat]

ho hum......told you so

 

good news you have the std stuff, if yyou dont need to fit the adjustable stuff...dont.

 

unless you can keep the stuff maintained it will become a pain in the bottom

[Tony]

ho hum......told you so

 

good news you have the std stuff, if yyou dont need to fit the adjustable stuff...dont.

 

unless you can keep the stuff maintained it will become a pain in the bottom

I'm just happy the rear set-back can be recovered so easily now since we have an existing template. This thread is very interesting though mat since the Drifty also has adjustable rear trailing arms... I look forward to some kinematic possibilities with your car on tdi's Arago 3D Visualiner.... Subject to tdi's permission of course.