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Holes for Cross Member Chassis Bolts


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I have fitted new floors in my Triumph Spitfire 1500 1980.

The floor panels I have fitted don’t have any holes for the front outrigger or the middle out riggers.

For the front ones I can drill up from the bottom, but for the middle out riggers I would have to drill where the captive nuts are and I’m concerned that I might accidental mess up the nut thread - the captive nuts are also able I move about which makes it more awkward.

Any one faced the same problems ?

Owen 

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AFAIK none of the floor pans have those holes pre-drilled. I don't recall exactly how I dealt with that on mine - it was a long time ago. I may have cut back the new panel so as to retain the relevant part of the original floor, which was still in good condition. As an alternative, drill a pilot hole from below, with a sleeve in the nut to protect the thread, then lift the body a bit, put some wood between the chassis and body to cover the stub outriggers, and drill out the pilot to full size from above. It's much easier to do that before fitting the box section to the floor, though.

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Just to check that  you're referring to the bolts through the seat pan (as per image). This can be an area with its own tricky little problems

Are the seat pan cross members (stiffeners) fitted as yet? If not then I suggest the holes in the floor pan need to be cut well oversize to allow lattitude when the SPCM is fitted (with its welded tubes inside). If 'yes' then the only possibiliy (with the car on the chassis) is to drill down from above through the tubes (not nice, but unavoidable).

I agree that damaging the threads in the caged plates could end up with hours of extra work to fix. Perhaps it's best just to remove the plates prior to hole making. With a bit of prising one or more tabs can be bent back and the plate released.

 

 

Screenshot 2022-07-24 at 20.10.58.png

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I pre drilled mine before fitting the floor pans but needed to adjust at least one of the holes. I did this with a Dremel cutting disc to carefully cut through the floor. So not a circular hole, but also completely invisible unless the body comes off the chassis. 

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I solved the problem by using a automatic centre punch from below. Three clicks and it made an impression on the other side.

I then centre punched the top side and used a spot weld cutter bit to cut a reasonable sized hole. The spot weld bit is larger than the captive nuts so it was easy to stop drilling once through the floor pan.

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Well getting the final bolts in place for the tub with the rubber washers was a hassle and sucked up plenty of time - but it is done now - phew.

Any hints and tips on how to get the bonnet alighted best ? 
 

Is it best to have everything lose, get the bonnet on the stays and then tighten up ?

 

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We left all the body tub to chassis bolts (front, middle and back) just more than finger tight and got there eventually!  The rubber bonnet lugs that fit into the bulkhead were useful for getting the linear position right and the height of them was adjusted later.  The biggest hassle was that the rear wheel alignment to the rear arches looked good before tightening down but seems to creep.  Got there eventually!

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On 05/08/2022 at 08:22, Pettifordo said:

Any hints and tips on how to get the bonnet alighted best ? 

Getting decent alignment on the moveable panels (doors, bonnet, valances, bumper, overriders) can be a most trying business, dependent on level of perfectionism.

Perhaps the main factor is that none of the moveable panels can be viewed in isolation. All need to be fitted up and progressively adjusted all in accordance with each other. Iteration is King!

It's worth taking account of just how many points of adjustment influence the bonnet alignment i.e.

*Hinge box fore-aft adjustment. HInge box up-down adjustment

*Bonnet location cones up-down adjustment. Bonnet location cones left-right adjustment

*Bonnet location plates fore-aft adjustment

*Bonnet catch strikers up-down adjustment (but also possibility to add shims under striker as required)

*Bonnet cross stiffener - some adjustment of tension of top panel (depending on type)

Innumerbale interactions, some balanced off against others under tension.

In principle the panel gaps shoudl be 5/32 to 3/16th inch all over. Hard to achieve that specification in practice but it's where to aim.

 

 

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