TC bell housings

Bob Schapel · Post by **Bob Schapel** » Tue Sep 06, 2022 3:59 pm

Just curious. One image shows a TC bell housing as I remember most, with a hollow behind the clutch shaft. The other shows a much stronger casting behind the shaft. It is the only one I can remember seeing like that. Was that stronger style standard on late TCs or was it an improved replacement part, modified due to a slight weakness in the original design? Any ideas?
Bob Schapel

antijam · Post by **antijam** » Thu Sep 08, 2022 3:34 am

Your upper picture shows a TC bell housing and the lower a later TD/TF unit. Certainly the clutch cross shaft boss on the TC was a notorious weak spot with many of them cracking in service - as the one in your picture appears to have done. Mine suffered the same fate and was subsequently repaired and beefed up with weld.
I don't know if the later design was intended to overcome this weakness, but it would certainly have helped.

Bob Schapel · Post by **Bob Schapel** » Thu Sep 08, 2022 3:21 pm

Thanks Antigam. Your observation strengthens the argument that it is an aftermarket replacement TC unit. The photo of the stronger bell housing is definitely a TC unit, not a TD/TF. The round protruding ridge on the front (which abuts the bearing outer) fits the larger TC gearbox and will not fit the smaller TD/TF gearbox. I have both types of gearbox and both types of bell housing in my shed. There is no sign that the ridge or any other machining has been modified. My theory now is that having improved the design for TD/TF, the factory used the later castings, but machined them differently, when making TC replacement parts. I agree that the stronger unit is a big improvement. I guess a question still remains ... Did the very last TCs have the stronger casting? I might ask a TD forum what type of casting the early TDs had. If the first TDs were the weaker casting, it would confirm the "replacement part" theory.

As a matter of interest, the bolt patterns are identical, which means that it is not difficult to convert a TD/TF/Y housing to fit a TC. I have done it myself by adding a bead of weld and then using a fly-cutter, piloted off the main bearings of a dummy block, to machine the different ridge.
Thanks again for your help.
Bob

Steve Simmons · Post by **Steve Simmons** » Sat Sep 10, 2022 8:39 am

The TD gearbox was very different from TC, and as far as I know it used a different bell housing from the start. So even the very first TD bell housing would not fit a TC, nor vice versa.

TC9849 had a standard housing, although I can't guarantee it was never replaced. But I don't recall seeing a TD-style housing on any TC that wasn't a modified TD housing.

Ray White · Post by **Ray White** » Sat Sep 10, 2022 9:04 am

Bob Schapel wrote: ↑
Thu Sep 08, 2022 3:21 pm
I guess a question still remains ... Did the very last TCs have the stronger casting?

MY TC is chassis 10030 (so one of the last ones) and the original bell housing has broken in the usual place...so I doubt a stronger casting was ever made.

Bob Schapel · Post by **Bob Schapel** » Sat Sep 10, 2022 6:08 pm

Thanks Ray. That helps confirm that my strong bell housing was not made during TC production, but made after they were strengthened later in the TD/TF era. It has been suggested that they were changed when the 8" clutch was introduced for the later TDs and TFs. This change included a thicker shaft which was moved back a bit, requiring the modified casting. Because mine is machined at the front to suit the larger TC box, it must be an after-market replacement.
Thanks for your reply. It has helped solve the riddle.
Cheers
Bob Schapel

Bob Schapel · Post by **Bob Schapel** » Sun Sep 11, 2022 3:36 pm

Thanks also Steve. Sorry, I somehow only looked at the last post and missed that you had also replied. Your TC is also a late one and helps confirm that TCs all had the early casting.
Yes, TC and TD housings are different because the machining to match the gearbox is different. However, a TD/TF/Y housing can be altered to suit a TC. I have altered two Morris 10 housings (same as early TD/Y) myself, but not the one in question.
For interest, I have attached the (rough) drawing I made when I modified one for a friend, whose TC housing had been horribly hacked.
Cheers from South Australia,
Bob Schapel

Simon Sadubin · Post by **Simon Sadubin** » Fri May 17, 2024 12:36 am

Hi Bob,

I recently purchased a spare bell housing for my MGTC - because the original was cracked in the usual place where the clutch fork bush passes through the side. It was also cracked around the edge of the oil seal recess.

When the replacement turned up I was concerned that it was the wrong part because at first glance it looked identical to the later TD/TF reinforced bell housing. But I've measured it up and sure enough it has the right size cutouts and retaining ring for the TC input shaft bearings and has clearly been made this way not modified so it was manufactured for a TC.

I think that you are right that these bell housings may have been made as replacements after the TC production finished using the later improved and strengthened TD pattern as a basis but machined for the TC gearbox at the factory.

The part number cast on the side is 24085 the brand marking is PBM in a hexagon. I wonder if the TD/TF bell housings are the same brand but have a different part numbers ?

best regards,

Simon Sadubin TC2575