TR4/4A 3A or 4A?

[habaneronut]

I knew my 58 TR3A (TS31073L)had a TR4A engine (CT51661E), but the more I dig into it the more I suspect that the unknown restorer just put a 3A body on a 4A frame and mechanical parts. Anyone know of any kind of a list somewhere that details all the differences between the two models and what to look for to tell various pieces apart?

Fred

 

[TR4nut]

Fred-

I doubt you have a 4A frame, as the track width is different and you would need to have wider fenders.

Moss Europe has a pretty good downloadable catalog for the TR3-4 cars:
Moss catalog

In the last pdf you will find a picture of a TR3 frame with all the dimensions so you can check yours. Easiest thing to visually check would be the front end - do you have a rack and pinion steering setup? If so, maybe a 4a.

Randy

 

[TRopic6]

Among other things, the TR4/4A has rack & pinion steering, while the 2/3 series uses cam & peg with a drop arm and four tie rod ends.

Jeff

 

[toysrrus]

Hi Fred:

What you may also want to check is the Rear End:

Is it an "IRS or Solid Axle"? If "IRS"; Its a TR4A:

But, As TR4nut points out, The Width etc is completely different: Personally, I would bet that you have a TR3 Frame:

If you look @ Moss`s current catalog (Pg. 64); You`ll find pics of a TR3/4 & 4A: Their All different:

What the heck; If she runs well; Who Cares:

Post some Pics;

Regards, Russ

 

[PeterK]

Fred,

It's common to drop a later TR4 or TRA engine and/or gearbox into the TR3A. It's got more power, a few more cc's, was readily available and is basically the same engine externally so a no brainer to swap. The later gearboxes had synchros in all gears so also an easy swap from a TR4 or 4A or even later.

As far as frames, although doable, would take more involved work to even put a TR3 body on the similar but wider TR4 frame. The TR4A frame is COMPLETELY different even in its live axle version, so doubtful that the body was put on a 4A chassis.

-PK

 

[Geo Hahn]

One more easy-to-check data point... the TR4 rear end will not have a drain plug on the diff, the TR3 will.

 

[Marvin Gruber]

The TR4 engine will set high on the TR3 frame unless the TR3 motor mount plate is put the on TR4 engine. The carbs will hit the hood otherwise. From one who did that years ago.


Marv

 

[Banjo]

Marv, Last time I encountered that, the motor mounts woulden't even line up. I had to swap the plate just to bolt it in.
those mounts musta been streatched to thier limits.
Fred, My TR2 will wind up with a TR4A motor, just because it's what I happen to have available, and the original TR2 motor is gone.
Like the others said, it's highly unlikley that it's a TR4 or 4a frame. the track is 4 inches wider. you either have to widen the fenders, or add width to the overall tub. It's been done.. the factory even did it,(Research "TR3 Beta") but it's not easy. It's more common to see a TR4 live axle put under a 3. the tires will just fit in the fenders if the little strut bars on the bottom of the fenders are extended a bit, but it dosen't look quite right.

 

[habaneronut]

Thanks for all the ideas, guys Didn't get out to the car today, but I hope to tomorrow and will check these all out. It's nice knowing whether I'm ordering parts for my "TR3" or "TR4" when I place the order. Working on the brakes right now, and they turn out to be late TR4A, at least the calipers are.

Fred

 

[Andrew Mace]

Part of the "fun" of these cars is determining what a previous owner might have changed on the cars. /bcforum/images/%%GRAEMLIN_URL%%/wink.gif If there's ever any doubt as to what you have, it's always good to cite a serial number for an engine, gearbox or rear axle / differential unit. Of course, it's not as easy with something like brake calipers; there, a visual comparison with reference sources might help (i.e., where later calipers have been installed on a TR3A).

 

[habaneronut]

I hadn't thought of it as "fun" Andy, kind of frustrating to a mechanical know nothing like me, but I guess it has been kind of an interesting educational learning experience. OK, it's getting to be more like fun as I learn more. So here's the latest.

Checked steering and rear end today, and as per help above, they are TR3. The TR4 parts I have identified so far are the engine, temperature guage, carbs (HS6 I think - the number stamped on them is AVC 410), and brake calipers (type "C").

Now, anything else easy to check? How about the heater? I understand that the TR4 heater can take a 7 lb radiator cap instead of the 4 lb on the TR3, and I can use all the help I can get cooling this thing down, I'm running a 4 lb right now. Not much difference between 4 and 7, but every little bit helps.

Fred

 

[Adrio]

My TR2 will wind up with a TR4A motor, just because it's what I happen to have available, and the original TR2 motor is gone.

Bamjo,

If you are looking for a tr2 head (for originality) contact me. My Tr3 has the TR2 head (with the different ports) and I did not know this until I had the head rebuilt. I am always on the look out for a swap for a TR3/4 head.

 

[Banjo]

Adrio,
I do have a low port TR2 head and I have the early intake manifold. But I'm missing the early, small carbs. They are easily spotted because they only have 2 mounting bolts, instead of 4 like all the later styles.
Early TR3s also had the low port head, but got bigger (4 bolt) carbs. so your TR3 may be correct. especially if it's a small mouth.