Refitting Tub to Chassis

[Pettifordo]

Does anyone have any tips for putting the tub back on the chassis ?

I’ve replaced the floors and inner sills but I haven’t fitted the cross members or welded up the front seam of the floor to the bulk head to give me some “play” when I get it back together.

I will need to drill a hole for the outer front mounting bolts and the 4 bolts for the cross members.

What is the best way to get the new holes in the right place ?

I bought the mounting bolt package from Rimmer Bros but I can’t see a picture of where all the bolts / rubber washers and shims go….any good source for that ?

[Neil Clark]

Look at the Moss website for Spitfires, or better still order the free paper catalogue.  Their drawings are really helpful indicating what goes where.  Not all the chassis / tub bolts are the same but if you use the Moss part number then refer to the crib sheet in the back it tells you the specific length etc etc.

Edited June 11, 2022 by Neil Clark
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[Neil Clark]

3 hours ago, Badwolf said:

Don't worry Neil, just click on the three dots, top right of your post, then edit, edit the post and repost. I will delete this in due course.

Thank you!

[chrishawley]

So much that could be said on this matter. Please regard any comments here as ‘my experience’ and not authoritative.

For ease of discussion I attach a schematic with the fixing points labelled 1 thru 6.

• AFAIK you didn’t have to weld the scuttle-to-chassis brackets at position #2. So position #2 is  an initial guide. I don’t think you welded near #5 so that’s a guide for the rear. But these positions are not datums as the holes are oversize. To look right when finished the lips of the rear wheel arches have to have a symmetrical relationship with the wheels/tyres. So (assuming suspension all tickety boo) a vertical straight edge off both rear wheels assists in estimating if the body is centred.

•Are the scuttle support brackets welded in (position #1)? If not then it may be a case of trial fitting the tub, getting a position for the brackets and then removing the tub again to weld. Drilling the floor pan correctly at #1 can only really be done from underneath. I did it by trial fitting, marking up then removing tub to drill.

•If you have a standard fitting kit then as well as fasteners the will be rubber pads and ali spacers. But I’ve never found a convincing chapter-and-verse on the fitment of the rubbers and spacers. My best guess is: rubbers at #2, #5, #6 and the Ali spacers anywhere as required to take up gaps or persuade the tub into shape.

• The floor cross members (#3, #4) can be a nightmare. The steel pressings themselves may require welded revisions in order to fit. Then there's getting bolts to align (UNF 5/16. 3", pointed). If your crossmember sections have crush tubes already welded in place then in some ways that's easier: The hole in the floor pan itself can be estimated and cut wide (e.g. stepper drill), the position of the section is then dictated by the bolts and welded revisions made to fit in with those. Well worth checking in advance that the captive plates on the chassis at this point are present, free moving and with good threads.

* Biggest mistake I’ve made is to view fitting the tub as an isolated procedure. Rather than provisionally/lighty fitting the tub and then fitting up bonnet and doors to establish the body fit as a whole. In future I’ll ensure good all round fit before committing the tub to a fixed position.

Lastly for now: Include the horseshoe (over transmission) as a part of a provisional fit for the tub.  The horseshoe’s fitting between dash and floor has minimal wiggle room and helps to guide/confirm that the body is entered (as well as needing to just fit).

 

[Bfg]

On 10/06/2022 at 21:18, Pettifordo said:

Does anyone have any tips for putting the tub back on the chassis ?

If it's of any help..    I removed all the shims and rubbers between the body and chassis on my TR and started again ..from what supposedly reassembled as standard. 

I set off by using 2mm thick self-adhesive neoprene on the underside of the floor panels, wherever the floor pressed-ribs crossed the chassis. This prevents any panel from vibrating against the chassis as I drive. In practice they act like sound deadening pads to absorb 'normal' vibrations.  < here > 

 

11 hours ago, chrishawley said:

I’ve never found a convincing chapter-and-verse on the fitment of the rubbers and spacers.

I quickly checked / measured (from above) using the end-depth-pin of a vernier gauge, the gap between the top of the chassis mounts and the underside of the floor mounts. I found the body was resting on the chassis in just a few places (but not on the body mounts).  In those places - I temporarily fitted 1/8" thick packer pieces of hardboard. 

I then measured all the body mount gaps, to see what rubber thickness and spacers were required. It didn't actually take very long (..despite my having added 8 more body to chassis mounts to this car).  In each case I ended up with just one or two rubber pads inbetween the body mount and the chassis.  Any additional packing was done by metal spacer (suitably plated &/or  painted of course).  I used 1/8" flat plate ..mostly 1-1/2" square (aside from the grouped body-mounting-plates for two, three or four screws). These thinner plates are more accurate (than the original 1/4" packer pieces) and they have a greater surface / load bearing area than the original type. 

The newly-fitted / aftermarket rubber pads (fitted by the Triumph specialist who replaced the chassis) were not reinforced rubber.  Because of this - when bolted up / compressed the rubber squidges out. Flipping useless.., so I scrapped most of those and reused the original (reinforced with cotton webbing) ones. 

My objective was ; to allow the body to sit (..and then be clamped) unstressed on the chassis (with the doors opening and closing correctly). As a bonus, this also meant that the body sat a little lower / closer fitting to the chassis (albeit perhaps only by 1/8 - 1/4").  

^ I also used rubber pads inside the car, on the body mounts, so the body mount holes are sealed from below by the rubber mounts and also from above by similar rubber pads.  I didn't use most of the supplied body washers.  Instead I again cut n' drilled 1/8" thick plates to cover the groups of bolt holes ..so again their load / any stress was wider spread (better distributed towards the sill, the bulkhead, and the folded floor edges).  These might not be felt in everyday driving ..but in the event of an accident (even if rolled) these body fastenings are not going to rip through the floor.!   I felt lock washers were not required when bolting through rubber, but I did use stainless-steel plain-washers on the load-distribution plates I'd fitted ..to prevent those from being scratched as I tightened the screws up (..I just don't like having rusty body mounts ! ).  

Despite my not having refitted the dashboard support (H-frame) - this car feels very much more 'held together' and quieter than before.

Perhaps that provides you food for thought. 

Pete