At 05:16 AM 8/15/2023, Barry Innes in Scotland wrote:
"We have had an inquiry from a potential customer who owns an MGA Twin Cam, who is asking us if we can convert his vehicle from the standard steel wheels to spoke wheels. -- I'm not sure why he would want to do this as I thought the distinctive standard wheels were one of the things to distinguish the twin cam from other models but as "the customer is always right", I have been asked to make inquiries to see if this is possible".

Interesting proposition, but I'm sure it has been done, maybe once, somewhere. I have seen it done the other way around, changing a standard pushrod engine MGA into a "Deluxe" with all round disc brakes and knock-off steel wheels. It is odd that the customer wants to spend good money to devalue the car (and make it harder to sell later), and you may want to explain that to him. There are no new TC wheels available, and used TC wheels are very scarce and worth big money (like $700 per wheel these days). But if money is no object, then personal preference can be satisfied. And some left over Twin Cam parts have good market potential. I will try to define the shortest route to the desired end, beginning with changing the least number of parts possible.

The rear end is very easy, since the Twin Cam rear axle is same length as a wire wheel rear axle. Just install the half shafts with splined hubs and the matching knockoff nuts from a 1500 wire wheel car, and it's good to go. But you do have to match the inboard splines on the halfshafts. Twin Cams were always 10-splines, same as MGA 1500 cars. Also TC knock-off nuts are different cone angle from WW K/O nuts, not interchangeable, so you have to swap those as well, The left over TC KO nuts are valuable (and came in two different styles).

Here is a list of part numbers and descriptions for the rear halfshafts with different inboard end splines and the mating differential sun gears.

ATB7206  Shaft -axle, 1500 WW		10-spline
ATB7122  Wheel  -differential, 1500	10-spline
ATB7204  Hub extension R/H WW
ATB7205  Hub extension L/H WW

ATB7386  Shaft -axle, 1600 WW early (26s)  Changed to BTB153 Com. (C) 82749 (different 
		inboard splines)
ATB7365  Shaft -axle, 1600 WW later (25s)  (the hub extensions did not change, same 
		outboard splines)
ATB7282  Wheel -differential, 1600 (26s)   Changed to BTB150 (25s) Com. (C) 82749 WW 
		(different splines)
ATB7204  Hub extension R/H WW		   -(same as 1500)
ATB7205  Hub extension L/H WW		   -(same as 1500)

Twin Cam (V2): ---(Take V2 data with a grain of salt)---
BTB153   Shaft -axle, T.C. (V2)	(10s)	Com. (C) 91240 (all round disc brake models) ???
ATB7122  Wheel  -differential (10s) -(same as 1500)	Changed to ATB7292 Com. (C) 2371
		-(7292 may be a typo, s/b 7282)?
ATB7252  Hub extension R/K		Com. (C) 91240 (all round disc brake models) ???
ATB7253  Hub extension L/H		Com. (C) 91240 (all round disc brake models) ???

Twin Cam (V3):
ATB1206  Shaft -axle, T.C.    (10s)	Changed to ATB7386 (??s) Com. (C) 2371 
		-(1206 may be a typo, s/b 7206)?
ATB7122  Wheel -differential  (10s)	Changed to ATB7282 (??s) Com. (C) 2371
AJC5182  Hub extension R/H, T.C.	Changed to ATB7252 Com. (C) 1840
AJC5183  Hub extension L/H, T.C.	Changed to ATB7253 Com. (C) 1840

As an aside, if you were to use WW halfshafts from a 1600 car, those have rolled involute splines, 26-splines early and 25-splines later. Then you would have to open the differential to change the differential sun wheels to matching splines. Alternately you could install a complete wire wheel rear axle assembly from any 1500 or 1600 car. Any of this is more work of course. In any case, do keep written documentation for all modifications for future maintenance.

The front end is somewhat more tricky. The TC steering rack is farther forward (not a problem), and the steering knuckles and arms are different, and the TC uses tapered roller bearings where MGA PR engine cars have ball bearing hubs. Also the TC knuckles have integral brackets for mounting Dunlop calipers, not like the 1600 with separate brackets for Lockheed calipers. And the brake rotors are different, and the calipers probably have different offset and mounting bolt pattern.

The WW front bearing hubs are one piece including the male splines and female bores for the ball bearings. All of the bearings are different ID and OD and width. You would drive yourself nuts trying to find either ball or roller bearings that could work to mate the wire wheel hub to the Twin Cam knuckle. Might be easier to machine up adapter rings to press into the WW hub to accept the (smaller OD) tapered roller bearing outer race. Even if you could, I suspect it would be equally tricky installing Lockheed calipers on Twin Cam knuckles, or adapting Dunlop discs to the Lockheed hubs. But the next alternative may be even more difficult.

The other way would be to swap out the knuckle (and steering arms and maybe the swivel pin along with it) to accept the wire wheel hub and ball bearings and Lockheed rotor and caliper brake parts (giving up the Dunlop front disc brakes) I recon that changes the brake hoses and steel pipes, and may require relocating the welded brackets on the chassis frame. That is, change the whole setup from Dunlop to Lockheed knuckle and brake parts. Also a slight toe-in adjustment if the steering arms are different angle. If you don't want to give up the Dunlop brakes, then you also have the problem of trying to adapt the Dunlop calipers (and probably also rotors) to mate with 1600 type knuckles (with separate caliper brackets) and the splined bearing hubs (the reverse of the problem from the prior paragraph). Either way you will also need some pain killers after banging your head on the wall.

The pushrod engine cars have a dual bore master cylinder for brakes and clutch. The TC uses two separate master cylinders and completely different pedal assemblies and mounting bracket. And I don't suppose you want to get into cut and weld and repaint to change the heater shelf aperture and/or MC mounting brackets (and also change the clutch slave cylinder if you did that). So least painfully wanting to retain the TC master cylinder setup. But there is a reason I mention it.

Both TC and PR cars have 7/8" bore brake master cylinders. But the TC MC has 1-3/8" stroke where the pushrod engine cars MC have 1" stroke. With Lockheed calipers, the increased flow form the TC master cylinder makes for shorter pedal stroke and about 38% heavier pedal force required. For this the customer would likely want a power brake booster. Aside from the cost, installing a remote power brake booster in line with the brake pipe is not too difficult (fairly often done). Find a convenient space for the booster, rig up a mounting bracket, make up two new brake pipes and a vacuum hose connection to the intake manifold.

If the customer doesn't like the booster in the engine bay it can be hidden inside the right front fender behind the splash guard. This requires a different fabricated mounting bracket, and running two small steel pipes and the larger vacuum hose connection through the inner fender. Easy enough with some bulkhead connectors, and it looks neat when finished. The remote booster has otherwise been mounted in the cockpit hidden behind the dash with similar bulkhead fittings through the firewall.

I don't know if the Lockheed disc brakes are functionally much different from the Dunlop brakes, just that the Dunlop parts were used (back in the day) to have four wheel disc brakes for the Twin Cam car. I don't suppose there would be any front to rear balance mismatch to notice with Lockheed disc in front and Dunlop disc in the rear. If this was a concern, maybe consider swapping out the rear brakes from Dunlop disc to Lockheed drum brakes. That likely requires a different hand brake cable, or maybe just swap out the whole rear axle for the standard drum brake model. All a big step backward, and probably not what the customer had in mind, just wanting wire wheels.