Brett James-McCall
Moderator
Guys,
This is Rene's build log. Please discuss this in the chassis section.
Brett
This is Rene's build log. Please discuss this in the chassis section.
Brett
A Riviera scratchbuilt GT40
- Thread starter REJ01
- Start date
Related to Eddie's question about the adjustments I made to fit the GTSTUNING MKI body, you will find attached a pdf file as summary of the 3 main dimensions I finalized after the body delivery .
Of course, all the "secondary level" dimensions are to be accordingly adjusted...
For me, I made the adjustments "on the field" , without specific new drawings ...
Anyway, from my recent experience, I would say that the sooner you get the body , the better it is...
In the future, if others scratchbuilders get experience with another body type, and a similar or close chassis, it would be interesting to get their revised dimensions.
To be discussed in the right section , of course ....
René
Of course, all the "secondary level" dimensions are to be accordingly adjusted...
For me, I made the adjustments "on the field" , without specific new drawings ...
Anyway, from my recent experience, I would say that the sooner you get the body , the better it is...
In the future, if others scratchbuilders get experience with another body type, and a similar or close chassis, it would be interesting to get their revised dimensions.
To be discussed in the right section , of course ....
René
Since my previous posts, I focused mainly on the drivetrain installation :
*Porsche G50 box install on the chassis , via 2 polyurethane bushings I made from Shore A 90 PU.
I understood that some ( Experimented...) builders use to bolt directly the engine and box on the chassis; for me, I was a little bit anxious of the :torsion, vibrations and similar, issues , and that is the reason why I used these reasonnably stiff bushings .
I plan to use the same stuff for the engine .
The final input shaft/cranck height is 160 mm from chassis bottom
*Lateral fork clutch drive via a specific shaft, similar ( I think..) to the older 930 box ; the hydraulic receiver is from BMW 3 series.
From the first manual tests I made , the clutch bearing is moving ....and the torque to be applied on the shaft is :8 kgm which should lead to approx 25 kg at the pedal.
I received this day all the plumbing/fittings from RallyDesign, and I plan to install soon the hydraulic line .
*Rear suspension , almost complete , excepted the shock absorbers.
But I still have to work on the uprights, for the bearings and hubs installation.
Can somebody give some advices on the suspension course : I planned on : + 3 inches compressed, and -1.5 inches extended; but it may have to be symetrical? Or other criteria ...Thanks for any inputs on the subject.
René
*Porsche G50 box install on the chassis , via 2 polyurethane bushings I made from Shore A 90 PU.
I understood that some ( Experimented...) builders use to bolt directly the engine and box on the chassis; for me, I was a little bit anxious of the :torsion, vibrations and similar, issues , and that is the reason why I used these reasonnably stiff bushings .
I plan to use the same stuff for the engine .
The final input shaft/cranck height is 160 mm from chassis bottom
*Lateral fork clutch drive via a specific shaft, similar ( I think..) to the older 930 box ; the hydraulic receiver is from BMW 3 series.
From the first manual tests I made , the clutch bearing is moving ....and the torque to be applied on the shaft is :8 kgm which should lead to approx 25 kg at the pedal.
I received this day all the plumbing/fittings from RallyDesign, and I plan to install soon the hydraulic line .
*Rear suspension , almost complete , excepted the shock absorbers.
But I still have to work on the uprights, for the bearings and hubs installation.
Can somebody give some advices on the suspension course : I planned on : + 3 inches compressed, and -1.5 inches extended; but it may have to be symetrical? Or other criteria ...Thanks for any inputs on the subject.
René
Attachments
I appreciate your support proposition D.
Here are the main sizings I measured yesterday on the chassis for the forecasted shocks lenght:
*REAR : - Full bump : 320 mm
- Ride height : 400 mm
- Full droop : 420 mm - Limited by a chassis rail ; can be extended to 435 mm
*FRONT : -Full bump : 250 mm
-Ride height: 320 mm
-Full droop : 360 mm
The upper fixing of each shock is adjustable ( Remote braket) within +/- 20 mm approx
The full extension of the FRONT suspension is only limited by the shock itself; is it acceptable ?
René
Here are the main sizings I measured yesterday on the chassis for the forecasted shocks lenght:
*REAR : - Full bump : 320 mm
- Ride height : 400 mm
- Full droop : 420 mm - Limited by a chassis rail ; can be extended to 435 mm
*FRONT : -Full bump : 250 mm
-Ride height: 320 mm
-Full droop : 360 mm
The upper fixing of each shock is adjustable ( Remote braket) within +/- 20 mm approx
The full extension of the FRONT suspension is only limited by the shock itself; is it acceptable ?
René
Hi Rene,
Pic is of the shock kits i sell.
The sizes you provided work perfectly. The rear shocks at 420 full open will give you a stroke of 140mm and the fronts will allow a stroke of 110mm. It is usually the shock that restricts the droop travel of the suspension so that is perfectly OK.
The shocks can be made with either rubber type bushes at each end or spherical bearings. Rubber bush types can be made with either 10mm or 12mm bolt holes and are typically 38mm wide although narrower bushes are available (20mm, 25mm, 32 and 35mm). Bearing types are 1/2" bore as standard but can come with spacers of width of 32mm or 38mm and bolt size 10mm or 12mm.
You can specify either 2.25" ID springs or 1.9". I prefer the 1.9 personally as they are smaller and lighter, but, 2.25 is conventional.
Hope that helps.
D.
Pic is of the shock kits i sell.
The sizes you provided work perfectly. The rear shocks at 420 full open will give you a stroke of 140mm and the fronts will allow a stroke of 110mm. It is usually the shock that restricts the droop travel of the suspension so that is perfectly OK.
The shocks can be made with either rubber type bushes at each end or spherical bearings. Rubber bush types can be made with either 10mm or 12mm bolt holes and are typically 38mm wide although narrower bushes are available (20mm, 25mm, 32 and 35mm). Bearing types are 1/2" bore as standard but can come with spacers of width of 32mm or 38mm and bolt size 10mm or 12mm.
You can specify either 2.25" ID springs or 1.9". I prefer the 1.9 personally as they are smaller and lighter, but, 2.25 is conventional.
Hope that helps.
D.
Attachments
Thanck you D. for your prompt and clear information ;
I am glad to see that there is no problem on the strokes and droop limitations because I must admit that I did not spent too much time on this subject during the chassis design !
This shocks/springs kit is a nice stuff ; I plan to use 1/2 " spherical bearings and 2.25 " springs ; what is the kit budget for such a configuration ?
René
I am glad to see that there is no problem on the strokes and droop limitations because I must admit that I did not spent too much time on this subject during the chassis design !
This shocks/springs kit is a nice stuff ; I plan to use 1/2 " spherical bearings and 2.25 " springs ; what is the kit budget for such a configuration ?
René
Here are some recent pictures of my build with mainly the front suspension and steering system installation :
*Anti-sway bar :The torsionnal central part is chromolly 25x2 and the arms are 2027 ally made ; In the present configuration , it is relatively smooth (around 167 lbs/inch - Thanks to EGLITOM calculation chart..), but I made it easy to replace (torsionnal bar only) by a stiffer one if needed from the tests.
The bushings are poylyurethane shore 90 , machined at the right size
I plan to use 20x3 mild steel for the rear bar, one piece only, with bended arms
*Steering rack : Comes from a manual Sierra steering rack , with a 2.7 turns rack from Rally design .
The steering rack height is adjustable in order to fine tune the "bump steer" from tests .
The steering shaft is adjustable and collapsible with a Wilwood steering wheel removable hub ; easier to get access to the driving seat!
*Ackerman : For the time being I installed a "Zero Ackerman" geometry ; but I made it modifiable in order to adjust later ...
*Dashbord : As I do not like too much the original dashboard, I made it from 25x25 aluminum rails with removable panels ....In fact my main objective was to keep very good access to the electrical /electronics which I will install inside ; but I plan to use foam and leather covering in order to give it a cosy aspect....
I am presently working on the clips and doors hinges installation , waiting for the engine shortblock to be sent from Fordstrokers in the next days...
rené
*Anti-sway bar :The torsionnal central part is chromolly 25x2 and the arms are 2027 ally made ; In the present configuration , it is relatively smooth (around 167 lbs/inch - Thanks to EGLITOM calculation chart..), but I made it easy to replace (torsionnal bar only) by a stiffer one if needed from the tests.
The bushings are poylyurethane shore 90 , machined at the right size
I plan to use 20x3 mild steel for the rear bar, one piece only, with bended arms
*Steering rack : Comes from a manual Sierra steering rack , with a 2.7 turns rack from Rally design .
The steering rack height is adjustable in order to fine tune the "bump steer" from tests .
The steering shaft is adjustable and collapsible with a Wilwood steering wheel removable hub ; easier to get access to the driving seat!
*Ackerman : For the time being I installed a "Zero Ackerman" geometry ; but I made it modifiable in order to adjust later ...
*Dashbord : As I do not like too much the original dashboard, I made it from 25x25 aluminum rails with removable panels ....In fact my main objective was to keep very good access to the electrical /electronics which I will install inside ; but I plan to use foam and leather covering in order to give it a cosy aspect....
I am presently working on the clips and doors hinges installation , waiting for the engine shortblock to be sent from Fordstrokers in the next days...
rené
Attachments
Hi Rene
firstly some fantastic work, I'm very impressed
I would re-consider having your anti-sway bar arms in alloy, as compared to the stiffness of the chrome-moly centre section, they are relativiley weak and will bend and eventually lead to a fatigue failure. Change them for the same design, but in medium-high grade steel
Regards
Andy
firstly some fantastic work, I'm very impressed
I would re-consider having your anti-sway bar arms in alloy, as compared to the stiffness of the chrome-moly centre section, they are relativiley weak and will bend and eventually lead to a fatigue failure. Change them for the same design, but in medium-high grade steel
Regards
Andy
Hi Andy,
Good advice ...
The arms will be obviously under sized when I will go to a stiffer bar for testing different suspension set up !
So I will build a spare stronger sway-bar with adapted steel arms and try to make a previous stress modelisation with Solidworks CAD ...
Cheers
René
Good advice ...
The arms will be obviously under sized when I will go to a stiffer bar for testing different suspension set up !
So I will build a spare stronger sway-bar with adapted steel arms and try to make a previous stress modelisation with Solidworks CAD ...
Cheers
René
It doesn't really matter what shape it is. The sway/anti-roll bar is just a spring.
I suspect the W shape is more for packaging reasons.
On an ARB related note, one of my suspension books has an example of using turnable blades. The amount of stiffness can then be experimented with easily. Otherwise its a case of using variable positions for the drop links (but can be undesirable as they change geometry and may end up with a non-liner response) or of course swapping the bar itself, an expensive and tedious task.
I suspect the W shape is more for packaging reasons.
On an ARB related note, one of my suspension books has an example of using turnable blades. The amount of stiffness can then be experimented with easily. Otherwise its a case of using variable positions for the drop links (but can be undesirable as they change geometry and may end up with a non-liner response) or of course swapping the bar itself, an expensive and tedious task.
W shaped anti roll bars i suspect are used for a dual purpose, because they seem to be shaped so that at some point the anti roll bar will hit part of the sub frame and i think OE designers use it as a kind of final bump stop device for extreme bump conditions.
Twistable blade type anti roll bars are useless. When you watch them on a 4 post test rig what you see is that they always deflect in the softest direction, except when the blade is turned so that the load is directly down the blade, so effectively you have a two position ARb. Full stiff and then at all other angles of twist it reverts to full soft. Ralt started running the ends of the blades in runners to prevent the blades from bending in any other direction than that of the load, but this is complex and heavy.
It's hard to beat a simple bar and a range of holes for effectiveness and ease of use.
D.
Twistable blade type anti roll bars are useless. When you watch them on a 4 post test rig what you see is that they always deflect in the softest direction, except when the blade is turned so that the load is directly down the blade, so effectively you have a two position ARb. Full stiff and then at all other angles of twist it reverts to full soft. Ralt started running the ends of the blades in runners to prevent the blades from bending in any other direction than that of the load, but this is complex and heavy.
It's hard to beat a simple bar and a range of holes for effectiveness and ease of use.
D.
Very interesting build 
I've wanted to build a GT40 myself for several years now but I have to wait until I have a good place to work at...
How much did the body cost? I've had the same plan myself, building the spaceframe myself and just ordering a body to reduce cost's and to be able to do the suspension exactly the way I want it!
I've wanted to build a GT40 myself for several years now but I have to wait until I have a good place to work at...How much did the body cost? I've had the same plan myself, building the spaceframe myself and just ordering a body to reduce cost's and to be able to do the suspension exactly the way I want it!
Johan,
I got the body ( MK1) from GTStuning for £ 2250 last year (This year price to check ); I consider it was a fair price ; some slight adjustments and fine tuning to make, but nothing difficult .
I have to say that I ordered the body after the main chassis frame build up ...Which is not the recommanded sequence to perform !
If possible I recommand you to get the body as soon as possible, and then finalize the chassis critical sizings : Width, bulkead tilt etc ....
I which you to find soon the right place for starting the build up....And then to post on the forum to show the progress ...
René
I got the body ( MK1) from GTStuning for £ 2250 last year (This year price to check ); I consider it was a fair price ; some slight adjustments and fine tuning to make, but nothing difficult .
I have to say that I ordered the body after the main chassis frame build up ...Which is not the recommanded sequence to perform !
If possible I recommand you to get the body as soon as possible, and then finalize the chassis critical sizings : Width, bulkead tilt etc ....
I which you to find soon the right place for starting the build up....And then to post on the forum to show the progress ...
René
Terry Oxandale
Skinny Man
Really nice build! love the rear uprights, and wonder what the bearing/stub/hub donor parts will be?
Thanks for the comments Terry,
The hubs /bearing donors are AUDI A6 or A4 , European models:
*Rear is a 82 mm OD bearing - Hub as shown on the picture , with a 38 splines drive, in order to match with VAG Transporter half-shafts I plan to install .
Bearing holders are still to be machined from 7075 ally....
*Front are 75 mm OD bearings , smaller hub , and similar bearing holders than rear
All this stuff may be a little bit heavy , but it should do the job ....
René
The hubs /bearing donors are AUDI A6 or A4 , European models:
*Rear is a 82 mm OD bearing - Hub as shown on the picture , with a 38 splines drive, in order to match with VAG Transporter half-shafts I plan to install .
Bearing holders are still to be machined from 7075 ally....
*Front are 75 mm OD bearings , smaller hub , and similar bearing holders than rear
All this stuff may be a little bit heavy , but it should do the job ....
René
Attachments
It looks I took a long time off since my previous post ....Sorry..The fact is that I continued working on the project, but I did not took the time to make pictures and comment the work done....
The main point is that I received the Shortblock I ordered from Fordstrokers: 331 CI , all forged , internally balanced .A nice piece of metal ....
I focused on the block-box ( Porsche G50 01J) assembly via home made adapter and flywheel.
The adapter is 20 mm thick 2017 Alu, and the flywheel is made from 7075 alu , with a steel insert .
The clutch is a standard 965 Turbo 911 device - used but in good shape
I was a little bit anxious on the engine-box concentricity; but at the end everything was in line and the box primary shaft rotates absolutly free in the flywheel centering bearing ( 15 mm ID).
I am now waiting for the parts I ordered a few days ago to Summit Racing:RPM Performer heads , Ford Racing water pump, covers etc ....
In fact, I will not get all the parts to achieve the engine ( Budget...) but I would be able to install the engine/box in the chassis and start the exhausts building : Bundle of snake of course ....
The main point is that I received the Shortblock I ordered from Fordstrokers: 331 CI , all forged , internally balanced .A nice piece of metal ....
I focused on the block-box ( Porsche G50 01J) assembly via home made adapter and flywheel.
The adapter is 20 mm thick 2017 Alu, and the flywheel is made from 7075 alu , with a steel insert .
The clutch is a standard 965 Turbo 911 device - used but in good shape
I was a little bit anxious on the engine-box concentricity; but at the end everything was in line and the box primary shaft rotates absolutly free in the flywheel centering bearing ( 15 mm ID).
I am now waiting for the parts I ordered a few days ago to Summit Racing:RPM Performer heads , Ford Racing water pump, covers etc ....
In fact, I will not get all the parts to achieve the engine ( Budget...) but I would be able to install the engine/box in the chassis and start the exhausts building : Bundle of snake of course ....
