Gapping a mono chassis

[Doc Watson]

After another member of the family was lost to cancer within 2 years (brother, dad and now mum) I am hoping to start welding the final parts of my 'Mirage Automotive' mono chassis together. I know there are set procedures for gapping the roof, doors, front and rear clips for various makes of gt40 but what order should I do it considering I havent fixed the rear bulkhead or a and b pillars to the chassis.

I was thinking of setting the rear clip in position which then dictates the rear bulkhead position which then sets the doors and front clip positions.... my chassis looks like this.... (photo below).

I do have the rear bulkhead, pressed roof inner and outer, window glass and dimensions for chassis from original drawings.

Any thoughts? also is each rear clip structure custom made for each chassis? if so where can I get one? Jim can you help???

Andy

 

[Doc Watson]

In the hope of generating ANY response.... I found this method of checking the front clip gaps when fitting..... any comments now?

 

Hi Andy,

I'm expecting my bodywork to arrive this week and will then deliver it down to Dave Brown. He has the bulkhead already fabricated and welded in place, so I guess that is the starting point. As I understand it, the rear clip is then fitted and used to line up the roof and then the doors fitted accordingly. Of course those who have been through the process may wish to chime in if I am wrong. Didn't see any evidence of the supplementary body gapping device you depict when I last visited Dave's workshop in February, so I must assume he uses a more hands off approach...

 

[Gus Richmond]

Doc, wouldn't the windscreen position be set in relation to the front firewall? Surely the datum would be set from the chassis, not the rear clip.
Just my uninformed opinion.
Kind regards, Gus.

 

I should have added that the windshield is already at Dave's so, as Gus suggests, I would imagine that it would be used in conjunction with the rear clip to get the roof just right.

Picture is with bulkhead in place and a roadster windscreen (not mine - the standard windsceen won't stand up by itself...) in situ temporarily.

 

[Jack]

In the hope of generating ANY response.... I found this method of checking the front clip gaps when fitting..... any comments now?

Can I "borrow" your special tool for awhile. See if it will fit for me.

 

[Cliff Beer]

Andy, I have zero experience finish welding and installing body on a GT40 so take this with a grain of salt....

I think my approach would be the following:

1. Don't finish weld anything until all body panels are trial fitted and close to correct. Tack weld the rear bulkhead, roof spider, etc. in place for trial fitting.

2. If my windscreen is set into the chassis I would start with that. If it is instead set into the cowl then I'd set the cowl in place, followed up with tack welding the roof spider and the rear bulkhead in position.

3. Then I'd make sure I have a complete set of matching body panels from a good source. I doubt a rear clam shell from one supplier is going to fit a spider and doors from a different supplier.

4. Then I'd trial fit all the doors and front/rear clam shell up against the (test fitted) cowl and spider, doing my best to note the appropriate mounting points and positions for the door hinges and clam shell hinges.

5. Once everything seems to line up then I'd finish welding the rear bulkhead and spider.

6. After that it's then a matter of getting the hinges all in the right position to line up the relevant panels. Finish weld and fit the hinges.

This is just my rough guess, and I could be totally wrong, but if you had a gun to my head this is how I would go about it.

Good luck!

 

[Dimi Terleckyj]

In the hope of generating ANY response.... I found this method of checking the front clip gaps when fitting..... any comments now?

Hi Doc

If you don't mind could I borrow your gapping tool next.

Dimi

 

[Jim Cowden]

After another member of the family was lost to cancer within 2 years (brother, dad and now mum) I am hoping to start welding the final parts of my 'Mirage Automotive' mono chassis together. I know there are set procedures for gapping the roof, doors, front and rear clips for various makes of gt40 but what order should I do it considering I havent fixed the rear bulkhead or a and b pillars to the chassis.

I was thinking of setting the rear clip in position which then dictates the rear bulkhead position which then sets the doors and front clip positions.... my chassis looks like this.... (photo below).

I do have the rear bulkhead, pressed roof inner and outer, window glass and dimensions for chassis from original drawings.

Any thoughts? also is each rear clip structure custom made for each chassis? if so where can I get one? Jim can you help???

Andy

Yip I would get it all on including screen as it your template .
Don't get caught by a half arsed fit up, fit up properly things change when you tighten bollts properly.
I recon if it came the crunch and something needs surgery the f/glass is the sacrificial lamb because your not going to be able to adjust the roof freely.
You need a wheel in the arches to get it even, I would have suspension fitted first.

Just to clarify are these panels together and need fitting or do you just have a sum of parts that make up the roof ect.
If that's the case you may need a jig.

Jim

 

[Charlie Farley]

Andy,
Have you got the front & rear body hinges, door hinges & associated hinge rods yet ?
Your are going to need those for sure. If my chassis would help you, you're welcome
to come and take measurements, maybe make a rudimentary jig from it....

 

[geoff]

Doors on , your 'A' pillars are all you can
use dash,windscreen pillar,door seal to A
Pillar this must be done with wheels on and
Wheel aligned to align rear wheels in the
Correct location with in their wheel arches.
These are the steps a body man would use