GT40s.com
MK-I  MK-II  MK-III  MK-IV  GULF  MIRAGE  J-CAR  LOLA
GT40s.com
Home Forum Gallery Support GT40s.com  
Register FAQ Advertisers Search Today's Posts Mark Forums Read

Go Back   GT40s.com > GT40 Technical Forums > GT40 Tech - Chassis,Brakes,Tires,&Wheels


GT40 Tech - Chassis,Brakes,Tires,&Wheels Chassis and Handling.

Reply
 
LinkBack Thread Tools Display Modes
Old 14th November 2009, 11:18 AM   #1 (permalink)
zetecmk2
3 Tenths
United States
 
Join Date: Feb 2009
Location: sussex
GT40: pile of bits!
Posts: 308
i need dimensions!

hello computer people, i need the measurement for the centre of the bolt hole for the front lower wishbone. no measurements on my plans!
something like "20mm up and 3 mm right". but i want to make sure. gtd chassis, cheers, glen

i need a hole here!
__________________
locost,,,oh yes!!
zetecmk2 is offline  
Digg this Post!Add Post to del.icio.usBookmark Post in TechnoratiTweet this Post!
Reply With Quote
Old 15th November 2009, 02:09 PM   #2 (permalink)
zetecmk2
3 Tenths
United States
 
Join Date: Feb 2009
Location: sussex
GT40: pile of bits!
Posts: 308
Re: i need dimensions!

bump!! please, i can't do much until i get this measurement, cheers
__________________
locost,,,oh yes!!
zetecmk2 is offline  
Digg this Post!Add Post to del.icio.usBookmark Post in TechnoratiTweet this Post!
Reply With Quote
Old 15th November 2009, 03:26 PM   #3 (permalink)
saxoncross's Avatar
saxoncross
6 Tenths
United Kingdom
 
Join Date: Mar 2007
Location: Norfolk, UK
GT40: Tornado
Posts: 688
Re: i need dimensions!

Hi Glen,
the position of these mounts will affect the bump steer, roll centre and and castor angle and will determinded by the design of stub axle and dimensions of the upper and lower wishbone. This is why people have probably been reluctant to give you specific dimensions

Have a read of Competition Car Suspension by Allan Staniford and it will help you determine where these points need to be

I know it's not the answer you were looking for, but you need to get it right to get the beast out of your car when its finished

Regards

Andy
saxoncross is offline  
Digg this Post!Add Post to del.icio.usBookmark Post in TechnoratiTweet this Post!
Reply With Quote
Old 16th November 2009, 04:13 PM   #4 (permalink)
zetecmk2
3 Tenths
United States
 
Join Date: Feb 2009
Location: sussex
GT40: pile of bits!
Posts: 308
Re: i need dimensions!

cheers andy, i suspected that was the case, but for now i just want the measurement of a gtd using standard nylon bushed gtd lower and upper arms, using standard granada front uprights.
i'm not scared of changing at a later date if it's that terrible, but by using gtd measurements with standard gtd stuff, i should be in the right ball park.
cheers, glen
__________________
locost,,,oh yes!!
zetecmk2 is offline  
Digg this Post!Add Post to del.icio.usBookmark Post in TechnoratiTweet this Post!
Reply With Quote
Old 16th November 2009, 08:20 PM   #5 (permalink)
PDub's Avatar
PDub
8 Tenths
United Kingdom
 
Join Date: Jul 2003
Location: London, UK
GT40: Tornado
Posts: 868
Re: i need dimensions!

Glen your probably best trying to get to see for yourself a standard GTD and getting the measurements - I understand what you are after but haven't got the right chassis!. Why not pop over to Franks, he's usually got several cars there at a time.
__________________
Best regards,
P.
PDub is offline  
Digg this Post!Add Post to del.icio.usBookmark Post in TechnoratiTweet this Post!
Reply With Quote
Old 16th November 2009, 08:50 PM   #6 (permalink)
zetecmk2
3 Tenths
United States
 
Join Date: Feb 2009
Location: sussex
GT40: pile of bits!
Posts: 308
Re: i need dimensions!

frank's done loads to help, as you have, so i didn't want to keep hastling him, especially for a measurement!! but if i have to, it's a small drive.
i can work it out from the pics i have, to within a couple of mm, which, going by the thickness of the shims i've seen on some chassis, should be ok.
just a small problem, it'll be ok in the end!!
__________________
locost,,,oh yes!!
zetecmk2 is offline  
Digg this Post!Add Post to del.icio.usBookmark Post in TechnoratiTweet this Post!
Reply With Quote
Old 17th November 2009, 04:48 PM   #7 (permalink)
mickky3's Avatar
mickky3
Bronze Supporter
United Kingdom
 
Join Date: Aug 2009
Location: Hampshire UK
GT40: building my own
Posts: 332
Re: i need dimensions!

hi Glen,
phone me,, i should be able to help you with the dimmension you are looking for
mickky3 is offline  
Digg this Post!Add Post to del.icio.usBookmark Post in TechnoratiTweet this Post!
Reply With Quote
Old 17th November 2009, 05:18 PM   #8 (permalink)
zetecmk2
3 Tenths
United States
 
Join Date: Feb 2009
Location: sussex
GT40: pile of bits!
Posts: 308
Re: i need dimensions!

cheers, pm me your no, glen
__________________
locost,,,oh yes!!
zetecmk2 is offline  
Digg this Post!Add Post to del.icio.usBookmark Post in TechnoratiTweet this Post!
Reply With Quote
Old 18th November 2009, 05:17 AM   #9 (permalink)
MikeP's Avatar
MikeP
10 tenths
United Kingdom
 
Join Date: Dec 2005
Location: Oldham
GT40: GTD
Posts: 1,101
Re: i need dimensions!

Hi Glen,
In order to settle on the wishbone pivot points you need to start with the steering rack and the location of the track rod ball joints. In order to avoid bump steer a simple rule is that the track rod ball joints and the wishbone pivots should all be in the same plane. This will give a good starting point. The idea is that as the suspension moves up and down the movement of the wishbones and the track rod move through their arcs in such a way that the steering arm on the upright stays pointing in the same direction. If the arms are wrongly located the upright will turn as the suspension moves and you will have bump steer. Bumpsteer can be tuned out if not too severe by moving the steering rack around - usually up and down. On GTDs a common way the get rid of bump steer is to raise the rack on shims upwards by 7/16". Put a laser pointer on the hub and move the suspension up and down and mark the points as it moves on a wall or flat surface. Juggle the rack around until the pointer dot moves in the closest to a vertical straight line.
The top wishbone should be shorter so that the upright will become more negative cambered as the suspension goes in to bump and vice versa in droop. The idea of this is to keep the tyre contact patch flat to the road as the car rolls in cornering. The ratio of the wishbone lengths will control the rate of change of camber. How much roll you will actually get will depend on the spring rate and the anti roll bar stiffness.
As a very rough guide the bottom arm will angle downwards about 0.25 / 0.5" and the top wishbone will angle upwards about twice as much. Remember that only the pivot points matter so don't be confused by the angle of the wishbone bars themselves - all measurements are using the centre of ball joints and the centre of the wishbone pivots.
If you check out the Staniforth book you will find that it tells you almost everything you need to know but not the whole story. His idea of a "string computer" works OK. The idea is that you construct a model of your suspension out of thin sheet such as plywood or plastic sheet and then move the model up and down to see what moves where and what happens to the angle of the upright. A very small change in the suspension pick up points can have a very big effect.
The quick solution is to copy exactly a set up that works. However you will also copy any issues with that set up. GTDs have a very low KPI due to the Granada Mk2 uprights and also very poor Ackerman which leads to tyre scrub on full lock. However there are cars around which have had these problems fixed.
Hope this helps.
Cheers
Mike
MikeP is offline  
Digg this Post!Add Post to del.icio.usBookmark Post in TechnoratiTweet this Post!
Reply With Quote
Old 18th November 2009, 03:39 PM   #10 (permalink)
zetecmk2
3 Tenths
United States
 
Join Date: Feb 2009
Location: sussex
GT40: pile of bits!
Posts: 308
Re: i need dimensions!

cheers mike, i like the "rough angle" of upper and lower arms, c to c, i should be able to work it out from there!
__________________
locost,,,oh yes!!
zetecmk2 is offline  
Digg this Post!Add Post to del.icio.usBookmark Post in TechnoratiTweet this Post!
Reply With Quote
Reply


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Display Modes

 
Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Looking for Dimensions of PSE Wheels CharlieM GT40 Tech - Chassis,Brakes,Tires,&Wheels 8 30th January 2009 09:56 PM
HELP!!! I need dimensions. daryl adams GT40 Tech - Chassis,Brakes,Tires,&Wheels 1 24th November 2006 08:19 PM
ZF Dimensions jac mac GT40 Tech - Powertrain/Transaxles 13 19th September 2006 04:40 PM
Suspension dimensions mkb GT40 Tech - Chassis,Brakes,Tires,&Wheels 3 8th June 2006 07:00 AM
Seat dimensions Paul Bearman GT40 Tech - Exterior, Interior, AC, & Trim 7 27th March 2006 05:07 PM


All times are GMT -4. The time now is 10:21 AM.