Evolution of the 356A T1 & T2 How they differ

[JTR70]

Though Basically the identicle car the 356A structurally evolved ever so slightly through its production from 1956 through 1959. Both of my long term personal project 356's are early T1 (1956) cars and after all these years I know them pretty well however my newest project, a 1959 T2 is showing me how similar they all are yet there are many evolved changes structurally. So aside from the obvious trim changes like Beehive tail lights to teardrops I thought I'd start this thread to show all the various component changes through the 356A run however when exactly these modifiactions occured and with what chassis # will probably never be known for certain but I did want to high light these small details just the same. Thanks for stopping by! Justin


Here is the trunk rear bulkhead wall and cable release tube area on this 1959 356AT2 chassis. I noticed it varied just a little from my early T1 car. Note the small grometed hole on the lower right side there. I believe this is for a wiring harness for maybe a parking brake release warning light?? Anyone know for sure? Anyway my T1 car does not have this hole in the floor.

Early T1 floor no small grommeted hole for a believed parking brake light.

looking at the T2 trunk again. Note the rubber grommet around the tube as it enters the bulkhead. There is also that arched relief above the tube. My T1 is differs here as well.

As you can see on the earlier T1: No arched relief and the tube is directly welded to the bulkhead.


The only reason for this evolutionary change at the bulkhead that I can see would be the introduction of this optional trunk lock. The relief is for the larger pot metal body and the non-welded tube makes it simple to cut the excess tube off in order to slide this housing on and install. Just a theory of course.

[JTR70]

One of the best ergonomic changes from T1 to T2 was the repositioning of the gear shift lever closer to the driver.

The 356T1 design had the gearshift postioned ahead of the heater control knob thus putting it further forward at the dash. A comparison shot is above with the T1 version on the right in Yellow and the T2 version on the left in bare metal. A much improved position. Heater control mounts are the skinny single hole tabs and the gearshift are the wider double hole tabs. I can still remember my hand going under the dash face to grab first and third gear in my T1. This change happened sometime in mid-late 1957. Seat track mounts up next. Thanks for stopping by! Justin

[JTR70]

Another slight change were the seat track mounts.


The 356A tunnels are virtually identicle except the gearshift placement described above.

The other noticable feature change on later T2 tunnels was the addition of this corrigated/waffle plate spot welded over the inner seat track mounts.
This plate simply amounts to a spacer to raise the seat track height.


The later T2 outer seat track footings incorporated these raised pedistals. The waffle plate on the tunnel was added to compensate for this new additional outer mount height to correct lateral alignment.


Here is my original early T1 floor. Outer track mount bolts directly to the floor. No outer raised T2 type pedistals so no waffle spacer plate either. If you have an early car like mine and you mistakingly used the later pedistals you may experience poor lateral track alignment and even binding if you don't have the waffle spacer on the tunnel.
Again when this change occured sometime in mid to late 1957 I assume. If your floor is gone just check your tunnel mounts to see if you need that outer pedistal or not. More trivial changes coming up. Thanks for reading this! Justin

[roy mawbey]

The position of the rear reversing back up light switch bracket in tne tunnel is also different from T1 to T2.

Roy

[JR]

Justin,
Those are some really definitive pictures showing the difference between the T-1 and T-2 bodies and their evolution.
I just acquired the 356 Registry Book 'Technical and Restoration Guide' whic is a collection of tech articles from the publications. It was 1st printed in 1994.
I'm sure most of you long time restorers have seen it.
This is the front and back covers.






I scanned a couple of pages from inside the book.



It would have been really nice to have had pictures like you posted in this book to clarify the writing, however I salivate over most anything 356!

This is Volumne One-Volume 2 is in the mail (snail).
I ordered htem thru Amazon.
Dick

[JTR70]

Thanks Dick, I am so glad this super fine detailed thread is interesting to you. I have seen that book you bought offered up by the various vendors for many years but never had a copy in my hand. Are you finding anything new in there?

Roy, thank you for bringing that one up. I completely forgot mention it and now is the perfect time while we're discussing the shift tunnel.

As Roy mentioned above, the "reverse light" switch was moved from a mount bracket welded on the inside of the shifter tunnel for the T1's to a drop bracket directly welded onto the shifter base itself for the T2's when the shifter position was swtiched. Above on the left is a later 356T2 shifter base with reverse light mount bracket. On the right is a 356 pre-A and AT1 shifter base with no drop bracket.

here is the inside of a T1 shifter tunnel with mount tab for the reverse light. T2 shifter plate is right next to it with its directly mounted replacement.

Here is the reason this change was made: you can see the T1 bracket in the center here and is accessable. Once the shifter was moved back on the T2 (left) there would be no possible way to get at this switch to install or remove it because its now partially sheltered by the tunnel.The front mount screw maybe but the back one, forget it. The easy solution was to then mount it on the base plate. Thanks for stopping by! Justin

[JR]

Justin,
I received the copy of Vol 2 of the 356 Tech and Resto Guide yesterday.
I think it is good, but I don't have the resto back ground and talent that some of you guys do.
It is really good info for me!
I paid $38 for it used and it looks new!
356 Registry lists it as being out of stock for $24.95.
I am having my distributor rebuilt now.
It was rebuilt 3 years ago and there is some concern is that there were some short cuts made so we are checking for its longevity-it is only $$$$$$$!
Here is a pic of the front and back covers and the 6 pages of discussion on distributors. Of course mine is a '18'.




Here are the 6 pages of the distributor section.

[JTR70]

Hey Dick, That looks like a fantastic technical resource! The distributor description and application was very interesting. Thanks for posting. Justin

Rear engine compartment bulkhead wall stamping changes between early T1 and late T1/T2.

1956 and very early 1957 T1 rear engine compartment bulkhead walls were a smooth convex panel. They were also "ALL" Carrera ready with mount brackets for the oil filter and twin coils which can be seen clearly in the photo above. A change soon occured in mid-57 T1's and remained unchanged for the later T2 walls.

Later T1's and T2's got this more complex relief embossed wall with no Carrera bracketry. I know this was transitional item and not just a T2 thing because I had late T1 cab with this wall in it.(61801)

Inner view of this new wall reveals that enlongated relief with two small metal ribs spot-welded to it. What was it for?? After following Bill Sargent's Faux cam build it became clear; the embossed relief is for the optional Eberspacher gas heater. The two ribs are for the mounting clamps to pass through as well as cradle the body of the heater. So the change in the wall was for this optional heat system. More detail changes to come. Thanks for reading this! Justin

[JTR70]

A slight change in the front bumper bracket sleeve mounts on T2. For whatever reason the factory had shortened the sleeve so it no longer ties directly into the front torsion housing. T1 sleeves run the entire length making it much stronger as a unit.

356 T2 bracket stops a few inches in front of the suspension horn.

Earlier T1 runs the entire length and are seam welded directly onto the horn. A Much stronger and better supported box side walls. I think they went backwards on this one.

[Manolin]

So this also explains the different shift levers themselves offered over the years.

[roy mawbey]

Dick and Justin,

Dick that info on the distributors like Justin mentioned above made excellent reading I made some copies to my hard disc. I still have my original ' 18 ' and its so importasnt to have the dizzy working well on the advance/ retard system. Oiling of the lower area with the springs and slider makles all the difference to make a good idle. Thanks again Dick for making that post. And let us know how the work went on your distributor.

Justin, I have a thought on why they changed the bumber iron rail you show above. For sure the T1 system where its welded direct to the suspension area looks a great job very neat and looks correct.
However, as I mentioned a while ago, the effect on a frontal impact on one side of the car where the main force of impact was applied to the bumper iron pushed the damage right back to windscreen area and deformed much of the sheet metal under the front wing ( fender ) even to the extent of creasing the corner of the front lid up by the corner of the windscreen.

By having that 2 inches of clearance is it possible it acted like a crumple zone to stop main damage to the suspension area? Direct head on collisions did not have the same effect as a corner blow.
I wish I could find the article on damage repair that I read some years ago, that explained where the forces on impact travelled too which made such a really bad result for repairing. Possibly it was the only thing the factory could do?

Only my thoughts of course!!!!!

Roy

[JTR70]

Hi Roy,

I think you are spot-on with that theory. Here's proof positive of it right here; makes perfect sense. Justin

They added a reinforcement strut at the base of the chassis here behind the suspension and weakend it ahead of the suspension by shortening the bracket mount. Makes perfect sense. Good eyes Roy!

[JTR70]

Here's more confirmation on that theory that once the lower reinforcing strut was added behind the suspension horn the bumper bracket mount was trimmed back.


This is Speedster 83142 which I worked on a few years back. Its a 1957 Beehive tail light car but it was showing signs of the coming T2 evolutionary change. Has the lower reinforcement strut at the bottom with original shortened bumper bracket mounts. Excuse the shoty repairs made by the old owner. This was a pain to reverse and get clean.

All new Zims parts installed. I'm realizing all the aftermarket parts are T2 style. The new bumper mounts are short as originally.


You can see the beehive tail light hole in this pic and a few T2 structural changes being phased in. A clear example on how these changes were ever so gradual during 1957.


Again going back to my Dec. 1956 T1 frame for comparison. No lower suspension reinforcing strut behind the horn.

With full length bumper bracket mount. Will see if this theory continues to hold water. More changes up next. Thanks for reading this! Justin

[JTR70]

Another little component change was the parking brake cable coupler block which went from a machined block of steel to a lighter cast aluminium piece.

The coupler block located inside this steel sheath towards the front of the tunnel. Couples the two rear cables onto the single up front. Other than the material used everything else remained unchanged from t1 to t2.

Pre-A and early 356AT1 steel machined coupler on the left and the later cast alloy T2 version on the right.

It is several ounces lighter than the earlier steel unit so if your building a light weight car go out and find one of these later couplers. its good for a few more ounces of savings. Justin

[Trevor]

Hey Justin - Very interesting thread you've got going here, I like it a lot. My car is a late 57, 10164Three, 50 away from the official cut off between T1 and T2. If you need any pictures or to double check something please let me know.