It's got to be a solid (live) axle TR4, and an early one at that. The CT prefix tells us that. Also the 4090 commission number indicates it's and early car, built in 1961 (the model first rolled off the production line in August). TR4 model ended in Jan. 1965 with CT 40304. All following cars begining in Jan. '65 were TR4A, although some were live axle fitted to the IRS frame (an estimated 25% of production, but no one really knows for sure). TR4A chassis numbers began with 50001. The live axle TR4A that were part the 50001 & up series continued to use the CT prefix, while the IRS 4As being built alongside used a different prefix: CTC. Although the two prefixes wereintermingled, the numbers beginning with 50001 were still kept consecutive.
Actaully, in terms of the rear brakes, this is all somewhat moot. The innards of the 9" rear brakes are the same and interchangeable for all TR4, TR4A, TR250/5 and TR6. Many TR3 and TR3A (including the so-called TR3"B") also used the same rear brake parts (but, I think there was some intermingling of 10" rear brakes still used on TR3 and TR3A).
Perhaps this particular car has had some swapping done, or has some strange aftermarket parts used on it. Yes, measuring to see if those are 10" or 9" drums will tell part of the story. Seems to me the "Lockheed" TR2/early TR3 rear axle shouldn't even fit under a TR4 (which has a wider track than the TR3s), but I'm not certain of this (it's not something I'd ever have reason to try). If memory serves, the brake backing plate mounting end on the "Lockheed" axle has a squared end and 4 bolts per side. The later "Girling" axle has a round end and 6 bolts per side.
Bob, Can you post a picture of the brake backing plate and the rear axle of the car, so we can see if they look like TR4... Or something else?
Weren't there also differences in how the brake shoes are held in place?
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