Floorboards

Rear Bulkhead

Fitting the RH sill guard is going to involve moving the car which is currently up on axle stands. Since the RH sill guard is already drilled and I know it will fit it can be fitted anytime.  In terms of productivity it was more important to complete the fitting of the floor boards and the rear bulkhead in preparation fro the final  fitting of the transmission and gearbox covers. I removed the floor boards and laid down a bed of sealer. I refitted  the floorboards , securing them with stainless countersunk screws.  I wiped away any surplus sealer with a damp cloth.  I then checked all edges above and below the chassis to fill any gaps with sealer and removing the surplus again with a damp cloth.  

I temporarily fitted the rear bullhead and marked it's position on the floor boards and down the inside of the rear body shell. This was to give me a guide to laying down the sealer. I removed the bulkhead and laid down a bed of sealer on the rear cross member, the floor boards and down the side of the rear body I put the rear bulkhead in place and secured it with M5 countersunk screws and penny washers . On the curved section of the bulkhead the buts against he inside of the wheel arches  I used M5 countersunk screws and penny washers each side of the GRP secured  with M5 Nyloc nuts. Where necessary I dished the penny washer to match the curve of the wheel arches and bulkhead.   With the rear bulkhead in place I  filled  any remaining gaps and cleaned off  any surplus sealer with a damp cloth.
 

I took another look at the floor boards and rear bulkhead and filled a couple of places I had missed in he wheel arches and next to the inner seat belt anchorages.

I temporarily fitted the gearbox and transmission covers  and marked there position on the floor boards so that I knew where to position the foam seals.  I found out that I could make neat holes in the foam sealer with a single hole punch.  before fitting the foam seals to the bulkhead and the floor boards I fitted 5 x M8 Rivnuts to the predrilled holes in the bulkhead.  I temporarily fitted the foam seal to the bulkhead, punching holes in it to line up with the rivnuts.  Satisfied with the line and length I peeled off the backing paper   starting at one end and as far as the first securing hole. I attached the seal to the bulkhead pressing it firmly i place and making sure that the holes were still aligned by inserting an M8 bolt through the seal in in to the rivnut. I then removed the next section of backing tape and repeated the operation and so on  until I reached the far end.
 

Bank Holiday Monday and at last I was able to get some time in the garage.  I perceived that there would be a potential problem fitting the transmission  (Prop Shaft Cover).  With the floor boards in place the edge of the chassis can not be seen. the transmission cover runs at an angle across the car.  There was a distinct possibility that securing holes drilled in each side could strike the edge of the chassis plate underneath unless I was are careful and worked out where to drill the holes, so that they were either completely in the wood of the floor boards or in the metal of the chassis.   I  put masking tap on to the floor boards and marked on it hit position of the cover.  I used a small off cut of metal to  to gauge the  distance of the edge of the floor boards to the chassis plate.  I transferred thee marks to the masking tape so that I could see the approximate line of the edge of the of the chassis in relation to the flanges of the cover.   I then worked out where to drill the holes so that they avoided the edge of the chassis plate . I found that if holes were place 1.0" from the front and at  at the centre point of the cross member at the back  with subsequent holes  on 7.0" centres between them.  Because every car is different and probably every cover is different these measurements are only a guide and would need to be determined. I transferred the marks to the cover and drilled small pilot holes . I fitted the cover and marked through the pilot holes back on to the chassis.   For the most part they lined up but I had to adjust the position of a couple of them to make sure they missed the edge and were located in the metal of the chassis.   I drilled the chassis with 3mm drill gradually opening it out to 4.2mm and then tapped the chassis to accept M5 PAN head screws.  those holes drilled through the floor board were drilled to M5 clearance and secured with pan head bolts, penny washers and nyloc nuts.  i took the cover off for painting.   I believe that I might still have to slot the front holes in the cover to improve the final  fit of  the gearbox cover over the transmission cover.

Not much progress over the past week. I slotted all the securing holes in the prop shaft cover to accommodate squeezing it inwards to get the best possible fit under the gearbox cover.  The rest of the time I spent making M8  studs to fit the bulkhead securing rivnuts of the gearbox cover.  The reason for doing this was to get accurate marks on the gearbox cover to indicate where to drill to fit he cover to the bulkhead.  The studs are inserted in to the rivnuts to protrude in to the cockpit but not touch the cover. The ends of the studs was covered in engineers blue. The gearbox cover was flange was covered in masking tape. The cover was put in place over the gearbox and as centrally as possible to the bulkhead aperture.  The studs were wound forward until they touched the flange of gearbox cover. The transfer of engineers blue to the masking tape indicates where the flange should be drilled.
 

I manages to sneak a couple of hours today.  I had to revisit the marking of the gearbox cover because I managed to smudge one of the marks and to be accurate I felt it best to re-do them.  I used the same method as yesterday which gives a clear indication of he position of the bolt hole to be drilled.  I drilled the bottom hole on either side with a pilot drill and then opened this out to 9mm. To mark the top central bolt I inserted a shorter stud in to the hole and marked the end with engineers blue. I made sure that only a little of the stud protruded through the foam and was not touching the gearbox cover  as I placed it over the gearbox I refitted the gearbox cover securing it in place two long bolts and tightened it up. tightening the bolts pulls the gearbox cover forward compressing the seal. I tightened the bolts sufficiently until the top of the gearbox cover came in to contact with the stud. the transfer if the engineers blue marked where the top bolt hole should be drilled.  I took the cover off again and drilled the hole as before.   I refitted the cover to check the hole alignments  all were perfect.  I have to repeat this for two more holes tomorrow.

I've made steady, if not fast, progress on fitting the gearbox cover over the past 2 days.  I've finished all the holes in the front of the cover and bolted it up tight to the bulkhead.  I have drilled through the side flanges of the cover through the floor boards ,making sure i did not hit any hidden obstructions under the floor boards .  I managed to match up the holes securing the front of the prop shaft cover with the overlap of the gearbox cover so that 1 bolt secures both together.  I positioned a second securing bolt for the rear of the gearbox cover, so that it came half way between the chassis plate and the gear box supporting cross member.  The rest of the cover was secured with holes at approx 5½" centres. The gearbox cover was secured to the floor boards using M5 PAN head screws , penny washers and nyloc nuts.  This was only a trial fit to allow me to mark the gear lever aperture and mark where to trim the gear lever hole to get full range of operation without fouling the cover.  To get these adjustments correct involved several removal and re-fitting of the gearbox cover. During one of these operations today, I found that two of the Rivnuts in the bulkhead had pulled through.  The bulkhead metal is very thin and constant fitting and removal of the cover had enlarged the hole  so that the rivnuts had come loose and pulled through the metal.  I would still recommend using rivnuts but I would fit them BEFORE fitting the bulkhead if I were to do it again.   I fixed the problem by fitting new rivnuts backed  a washer to give more support and depth for the rivnut to grip.  Despite take care over the measurement and positioning  of the gear lever hole I got it slightly wrong.  I had allowed, as I thought, enough margin in the size and position to compensate fro the compression of the seals and the final position of the gearbox cover.  However now that it is in place I was too far forward and  slightly off at a diagonal.  with the cover in its final position I remarked the hole correctly removed the cover and cut out the new hole for the gear lever.  to  correct the mistake and end up with a circular hole I could either enlarge the gear lever hole, or keep the new hole size and add a little filler  to one side. I chose the latter.   I made a tube of the correct diameter to act as a former and preserve the circularity of the hole. I inserted it in to the cover  and  greased it lightly so that it would not stick to the filler.  I made bed for  the filler by sticking masking tape to the inside of the  cover and up against the tube.  I filled the gap with P38 filling compound and left it to set.
 

There is light at the end of the "transmission" tunnel.  The filler had set and the grease had stopped the former sticking to the filler.  I sanded down the filler to the contour of the gearbox cover. both inside and out.  It was a little low in a couple of places so I made up some more and applied it again.  When it had set I rubbed it down again until it was smooth and flush with the contour.  A light coat of grey paint primer and you couldn't tell there was ever a problem.  I refitted the gearbox cover and tightened it up to the bulkhead. this time the hole for the gear lever was perfectly placed. I took the opportunity  to cut the top of the gear lever to length so that the sleeve fro the new gear knob was correctly placed.  Now that it  s cut to size, I'll get in touch with John Hopkins to pin the sleeve to the gear lever.    Time to take the cover off again and fir the rubber seal to the floor.  I lid the seal along the floor in the approximate position. Marked where the first screw hole would come on the seal and punched a hole in it using a single hole punch. O placed a screw through the hole and in to the hole in the floor board and progressed to the next hole, repeating the process until I reached the far end.   I the started at one and stripped of a short section of the backing. I stuck the seal in place, making sure the screw lined up with the corresponding hole,  I progressed along the seal repeating the process until I reached the far end. At the far end I cut the seal to length with a pair of sharp scissors.  I repeated the process for the seal on the other side. With the floor seal in place the gearbox cover sits higher.  The bulkhead holes need to be slotted so that the bolts line up. I use the same method that I used for the original holes.  I placed masking tape on the face of the gearbox cover flange and fitted the cover approximately in place.  I inserted some studs dipped in engineers blue from the engine compartment side of the bulkhead and screwed then in until they touched the cover. The transferred blue marked where the flange needed to be drilled to align with the bolt.  I drilled the corresponding hole in the flange and slotted it until it met the original hole.  I repeated this for the remaining 4 holes in the flange to attach the cover to the bulkhead.  The slots allow the cover to take up its correct position as the seals are compressed when the cover is bolted to the floor.  Similarly the holes in the flange to bolt the cover to the floor need to be slotted to accommodate the compression of the bulkhead seal as the cover is tightened to the bulkhead.  A similar process to marking the bulkhead holes can be done with the floor holes. Dip the end of a bolt in engineers blue,  insert it in the hole from underneath the car. The transferred blue dot marks the position of the bolt on the flange. I drilled out the hole and then slotted the original hole.  I trial fitted the cover to check the slot alignments with the hole the floor all was OK.