[TR] TR6 Plastic transmission Tunnel Fit

[Harrymague at aol.com]

Thanks so much.  That is a great explanation .
Harry
 
 
In a message dated 3/13/2017 9:14:11 A.M. Eastern Daylight Time,  
john.macartney at ukpips.org.uk writes:

 
I do hope my  verbosity doesn’t auto-trash this reply from the server but I’
m able to tell  you why these replacement tranny covers don’t fit as 
expected. From what I  have learned this far, it’s a universal problem and I’ve 
found the answer in a  sheaf of papers written by my Dad back in the late 50’
s. For those who are not  aware, Dad was Quality Control Manager and Chief 
Inspector at Standard-Triumph  until the Leyland take-over. 
The problem first  raised its head with the start of Herald production. 
What few people know is  that key parts of Herald assembly were made by 
different suppliers namely the  scuttle (firewall) bonnet, floor and rear deck. As 
a result and because the  bodies were built up ‘visually’ and not in proper 
body jigs, the conformity of  panel gaps and door shut lines were achieved 
by loosely assembling the entire  structure and then using a variety of 
timber levers and rubber mallets to  achieve overall alignment in which the “it 
looks about right” was the prime  decider. This was by no means an exact 
science and in the early years of the  Herald’s production life (certainly the 
first two years) resulted in  horrendous warranty costs through water 
leakage. Gradually, they managed to  get the issues sorted but with the arrival of 
the TR4/4A/5/250/6 the bodies  were assembled in much the same way. That’s 
why we never took visitors into  the body assembly area as the somewhat 
brutal way that things were put  together was not felt desirable for visitors to 
see! 
The issue of the  transmission tunnel was a major headache. The factory fit 
version was made of  a semi-liquid form of chewed cardboard put over a 
perforated zinc former and  bonded with fish glue which was then baked to harden 
the assembly off.  Initially, holes were drilled in this cover for securing 
bolts to be fitted  but more often than not the holes failed to line up 
precisely with the chassis  securing lugs. This was overcome (eventually) by 
briefly fitting inked spikes  into the chassis lugs, resting the tunnel 
assembly on them and then hitting  the appropriate point with a piece of one inch 
die tube to achieve the  approximate hole punch location. The tunnel was 
then removed, inverted and the  ink marks on the underside and scuttle mating 
surfaces showed where the holes  needed to be punched. Having now determined 
the more or less precise position  of the holes along the front and side 
edges, the tunnel was then put into a  separate jig to mark off how much of the 
tail end needed to be removed with a  circular saw. 
Because of the  ‘variability’ of where these holes eventually appeared 
means that no two cars  were exactly the same in all critical dimensions and 
this is what the parts  aftermarket has entirely overlooked. Those who now 
make these tunnels have  assumed (incorrectly) that the size and positioning of 
the required holes was  identical in every case and that’s why they’re 
such a s*d to fit and why  they’re nearly always too short. Simply, someone has 
obtained an old cover,  assumed its dimension was/is a one-size-fits-all 
and made accordingly. The  originals were always made longer than necessary so 
there was a tailend to  remove and that amount of removable section depends 
entirely on each  individual car. 
How do you overcome  it? You can’t – unless you’re really lucky. A strip 
of soft aluminium to  bridge the back end is probably the only option open to 
anyone. With regard to  where you locate heat mat, I feel the underside is 
probably better because if  you plan to fit new carpets, these too will 
probably come to fit an ‘exact’  dimension rather than a sloppy one which was 
how the carpets were made in the  past. 
Hope this  helps 
Jonmac 



 
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