Evolution of the 356A T1 & T2 How they differ

[roy mawbey]

Oh dear,

I did not check the pics before sending. My car was not supposed to be on there

I enter the correct pic now.

Sorry

Roy

[JTR70]

Roy, thank you for sharing all of this great information! Cut-off points by chassis number are the most interesting to me. Thanks once again! Justin

Here's a small structural difference I overlooked concerning the lower frame reinforcement behind the front suspension talked about on page 3&4 of this thread. The T1 cars had an "inner" reinforcement strut.

Early T1 version pictured without the lower reinforcing strut at the outer base of the frame.


Again later T2 version here with lower reinforcing strut.


Here is a detailed shot of an early T1 inner chassis. The factory had added this U-shaped reinforcement strut. This small detail found only on chassis without the outer version.

here's a bottom shot of it and clearly overlaps the "frame" flange. It is spot welded in place all along its length and seam welded at its end onto the Toe-board bulkhead.

Later undisturbed T2 with outer strut and clearly no U-shaped reinforcement to the inside like on the earlier T1's. more details later.

Thanks for reading this! Justin

[merbesfield]

Excellent detailed shots of a correct T2 battery box floor! Thank you for helping on such a cold day Roy!

As you can see in Roy's detailed photos above the 356AT2's floor incorporated a center strengthening rib with the addition of a tow hook. Also no drain holes in the floor.

By contrast this early 356AT1 floor is flat with no center rib or tow hook originally fitted. This early version also had a drain hole with metal caps over them.

Lateral pressed in ribs and reinforcment brace were all identicle through T1 and T2. I can only speculate that the other changes to the floor coincided with the rear bulkhead wall change described previously. Agian all vendor replacement floors are T2 style with the center rib and are incorrect for 1956 and early 1957 356AT1. Thanks for reading this! Justin

Thanks again Roy!

Great thread here. I wanted to add my small observation. My car, a 57, #58648, only had one of the battery pan drain holes with the exterior hat covering the hole. Justin's had two. I am positive mine never had the second one because the car had never had work on it until I touched it.







"Drain Hat" that I fabricated to match original. Just like Justin did, only I had one, not two.

[JTR70]

Hey Mark,

Thanks for posting up these shots of your original T1 battery box floor. I sure wished I would have had these pictures as I was redoing mine for the third time. I know now that I made a mistake following the photo in the '56 factory manual by installing the second drain hole as the example car showed. It must have been a super early or proto type for the illustration. I just did not have anything else to go by. oh well, easily reversable and besides I have installed several additional drain holes throughout my restoration. Another detail I missed that yours shows is the two small seam welds along both sides of the battery recess area. Again, sure wished I would have had these shots back then. Thanks for posting them! Justin

[merbesfield]

[quote="JTR70" post=8772]Hey Mark,

Thanks for posting up these shots of your original T1 battery box floor. I sure wished I would have had these pictures as I was redoing mine for the third time. I know now that I made a mistake following the photo in the '56 factory manual by installing the second drain hole as the example car showed. It must have been a super early or proto type for the illustration. I just did not have anything else to go by. oh well, easily reversable and besides I have installed several additional drain holes throughout my restoration. Another detail I missed that yours shows is the two small seam welds along both sides of the battery recess area. Again, sure wished I would have had these shots back then. Thanks for posting them! Justin

I wouldn't change it if I were you. They should have put two in, it seems like the smart thing to do.

[JTR70]

T-1 to T-2 Steering box upgrades.

From the beginning all the 356 Pre-A's on up to the early 1957 356A T1 cars were fitted standard with the Type 1 VW Beetle steering box. Sometime in mid-production 1957 with the change over to the 356A T2 the superior ZF steering box was introduced and continued unchanged up through productions end in 1965.

The standard VW Type 1 box as fitted to ALL 356 cars until mid-1957.

Absolutely no special modifications internally for Porsche version boxes like a quicker ratio etc.

The one and only physical difference between a box originating from a VW versus one from a Porsche was this "locating" dowel pin in the clamp saddle. Original Porsche boxes had them where VW's did not. Also starting in 1956 the pitman arms had an extra hole added for the new steering damper. 356 Pre-a Pitman arms were standard VW.


Late 1957 356A T2 ZF Steering box as fitted to all cars up through 1965. Note that extra 3rd hole as described above for the steering damper on the end of the pitman arm.

Since its introduction the improvements to an earlier 356's road manners has been duly noted in many old books and manuals. Though it is a bolt-on upgrade its larger size can prove to be tricky during an installation into a T1 or earlier 356.

[JTR70]

Another corresponding change directly tied to the steering box upgrade was to the drivers side "short" tie-rod assembly. Again All Pre-A's and 356AT1's were utilizing the stock VW 1 piece tie-rod unit which had fixed ends and were non adjustable or individually replaceable.

One-piece individual unit pictured above the later ZF 356AT2 adjustable unit.

T1 Ends were crimped onto the tube.

The bend or "kick" in the T1 tube is factory and was there to improve the approach angle of the tie-rod at the pitman arm. The long side tie-rod assembly remained the same for all 356. More detail changes to come. Thanks for reading this! Justin

[JTR70]

356T2 spindle upgrade.

All pre-A and early 356AT1's not only ran the stock VW steering box but they also used the stock VW type 1 front spindles. The later 356AT2 improvement came in the form of a much stronger snout and the elimination of old style ball-bearings to the improved roller bearing design. This change must also have coincided with the ZF steering box introduction.

Early VW version T1 snout on top and later improved T2 style snout on the bottom. The only difference made to the VW spindle for Porsche brakes was the inner pressed on spacer and ball-bearing race. I think also Porsche used brass bushing's for the link pins were as VW used steel bushings. Stock VW otherwise.

Side by side comparison. Other than the snout these units are completely identical. T2 spindles would remain unchanged all the way the end of the 356 drum brake beginning in 1964.

[JTR70]

Small drum brake differences. While all the Pre-A and 356A drums were virtually identical there were some small subtle changes. Front drums:

Early Pre-A and 356AT1 front drum configuration.

This is an early 356AT1 front. What makes it different from the later T2's are the lack of small ventilation holes drilled in the perimeter and the early ball bearing cages and races.

Still has the early ball bearings which work on that VW T1 spindle pictured earlier. These can be easily upgraded to the later bearings with a kit but this one is Pre-A and AT1 detail correct.

1957 T1 coupe 58367 with its original drums. No ventilation holes on the edges. I can only guess the holes were introduced later for more air and to allow the shoe dust to escape. Roy, I don't have a good shot of a later T2 drum with the holes. Do you have a clean shot of yours? Thanks! Justin

[roy mawbey]

Justin,

The T2 link pin bushes were bronze and not steel.I guess 20 years ago I changed some link pins and the only set I could get were VW steel versions. Now I know Mike Smith PRS can supply the correct versions.

I can say the VW version has worked well so far. But I do grease the car very often.

Attach the photo of the dust release holes in the T2 drum. I also mention the brake linings have slots across them to also help release the dust. I don't remember if pre-a or T1 had those slots cut in the lining?





Roy

[JTR70]

Thanks Roy! Yes, correct I meant ALL 356 both T-1 and T-2 came originally with bronze link pin bushings. The VW version kits had the steel bushings. All completely interchangeable of course.

Rear drum differences:T1

By slight contrast to Roy's later T2 drum shot in his last post this early pre-a/AT1 rear drum has no ventilation holes at the edges. There is also a small tell tale threaded hole for the oil slinger mount bolt by the spline crown that later became the T-2's weep hole. T-1 weep hole is out at the far edge.

Early T-1 removable steel oil slinger

later T-2 version with incorporated slinger or catch. And with perimeter ventilation holes.
Thanks for reading this! More to come...
Justin

[Vivancos9263]

[quote="JTR70" post=6190]Another slight structural change from T1 to T2 was to the rear battery box bulkhead wall. Though practically identicle in construction and appearance there was one obvious change and another not so obvious.

Early T1 wall with left access cover spot-welded in permanent. RHD Early T1's would most likely have the right cover welded on.

T2 bulkhead wall. Both access covers are now removable. This change was here by '58 and perhaps coincided with the introduction of the ZF steering box. Maybe late '57 T1's had this obvious change.



Here is the not so obvious difference. The recess for the battery was widened by a 1/2 inch along with the cover change. Early T1 example above showing just better than 9.5 inches across.

T2 version measuring just better than 10 inches.


Here is a direct comparison with an original T2 lower flange section and a T1 Bulkhead wall. Reutter widened this area a full half inch.

Going back to T1 speedster 83142 and my earlier statement that all the new replacement panels are T2 style. I could not get this wall to fit between the "frame rails". I had to cut it in half and remove a half inch out of the center. Note the T2 style twin removable access covers. I at first thought this was a mistake in the stamping until the '58 coupe arrived. Its lower flange provided the example above this photo and the confirmation that these were in fact different.

New wall cut and sitting in my T1 coupe for fitment confirmation. Fit like a glove now. note the 1/2 inch of overlap that had to be removed.
More to come. Thanks for reading this! Justin[/quote

Bringing back this old post to try to understand the early T1 battery wall with the covers. If there is a half an inch difference in the battery well, show on the T2 Simon seen panel cut to fit, then is the trunk wider on the T2? Are other panels different? Or the difference is accounted for on the rest of the panel so the simmetrical parts where the covers are build are somehow shorter or have less material around them?
Thanks
Ignacio

[JTR70]

Hi Ignacio,

Thanks for joining us and welcome!

Honestly I never really followed up on where they made the change to accomodate the widened recess in the wall. I don't think the trunk is wider as the lateral panels mount inboard of the torsion tube horns so they could not have changed that. Looking back at the pics it seems they just overlapped the lateral panel sections (access holes) a little deeper to offset the width. I'll take a few measurements and get back to you.
Welcome once again!
Justin

[Vivancos9263]

Thanks Justin, i need to replace this panel and starting with a Simonsen wall i'll appreciate any info on this topic. I guess there was a change on the market batteries or maybe the need to include one with slightly bigger amperage that motivate the change and also probably the corresponding different battery cover. I'll check on the parts catalog about this.
Ignacio

[JTR70]

I can get you those measurements but if your car is T1 and you've purchased that same Simonsen's wall you will have to narrow the battery recess to be correct and for it to just plain fit in there.
Justin