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TR2/3/3A TR3 9" versus 10" Brakes?

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K

karls59tr

Obi Wan
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TR3 9" versus 10" Brakes?

When did the TR3's get switched over to 9" brakes? Was the Lockheed set up for the 10" brakes only and the Girling set up for the 9". If a 59 TR3 with a commission number in the high 60's has a 10" Lockheed brake set up is there a chance that this car has the earlier diff swapped in? Karl
 
Re: TR3 9" versus 10" Brakes?

There's a fairly good list of changes to the early TRs by commission number on the VTR site. Notably, from that list:

--TS 13046 Changed from Lockhead to Girling Braking System, Changed Master Cylinder, Front Disc Brakes, Rear Brakes, Rear Axle, Differential, Suspension (1956)

--TS 56377 Changed to 9" Rear Drums (1959)

Almost certainly, a post-TS60001 car would have 9" Girling rear brakes as original fitment. Offhand, I don't know if the Lockheed backing plates and other bits even bolt up to the later "Girling" axle, or vice versa; either way, though, the Lockheed brakes were long gone by 1960.
 
Re: TR3 9" versus 10" Brakes?

So if someone had swapped a Lockheed braked rear axle into a post 60's car then that Rear axle is likely the earlier axle. Does that make sense?
 
Re: TR3 9" versus 10" Brakes?

Hi Karl,

I have two post 60 000 TR3A's. The race car had been converted to 10" drums but I have since converted it back to 9". So, to answer Andrews question, it does look like the 10" and 9" will fit the later axles.

Cheers,
M. Pied Lourd
 
Re: TR3 9" versus 10" Brakes?

The earlier Girling axles definitely came with 10" brakes (several slight variations of these actually). While it's not impossible that someone has put the early Mayflower axle in your car, it was generally regarded as weak even back then, so it seems unlikely to me. They are actually getting rather scarce, at least partially because so many of them have been broken! More likely, IMO, you just have 10" Girling brakes.

One interesting point though, the 10" Girling brake drums were actually the same part number as the 10" Lockheed front drums! So just looking at the drum won't tell you what's inside.
 
Re: TR3 9" versus 10" Brakes?

Am I correct, though, that a glance at what's sticking out of the backside of the brake backing plate would tell you which brakes are inside, i.e., square-post adjuster and brake line directly into wheel cylinder for Girling v. (I think) a banjo fitting on the wheel cylinder (pipe on one side and bleed screw on the other) for a Lockheed wheel cylinder?
 
Re: TR3 9" versus 10" Brakes?

also, the Lockheed set up will have four bolts to the backing plate vs. six for the Girling set up.
 
Re: TR3 9" versus 10" Brakes?

Andrew Mace said:
Am I correct, though, that a glance at what's sticking out of the backside of the brake backing plate would tell you which brakes are inside, i.e., square-post adjuster and brake line directly into wheel cylinder for Girling v. (I think) a banjo fitting on the wheel cylinder (pipe on one side and bleed screw on the other) for a Lockheed wheel cylinder?
Click to expand...
Yes, that's exactly right, Andy.

But it wouldn't be out of the question to redrill the backing plate; so the type of brakes don't necessarily define the type of axle. It's easier and surer IMO to look at the flange where the backing plate is attached to the axle housing. As noted above, the early axle has a squarish flange with 4 bolts, the later, stronger axle has a round flange with 6 bolts.

Oh, and just because I learned this the hard way : the TR4 axle is wider than the TR3 axle. It will bolt up, but you'll likely have trouble with the tires rubbing the fenders even with 165 tires.
 
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