Re: TC diff. bearings

[Neil Nelson]

Roger, Thanks for the info. Since we were talking about a TC the info I passed along to Terry was correct for his car unless someone has already done the tapered bearing change. I look forward to your info being posted by Walter. It really sounds like a better more permanent fix. You stated that the Moss bearing wouldn't last as long as the original. Since most of the TC's I have seen dismantled were over 40 years old I wonder just how long the original bearing lasted and how long it had been in unauthorized pieces. (Little T's with balls.) Any idea what the expected life of an original bearing verses the Moss replacement might be? Neil Nelson TC 0526 -----Original Message----- From: Roger Furneaux [mailto:Roger.46TC@virgin.net] Sent: Saturday, June 02, 2001 8:44 AM To: Neil Nelson Subject: Re: [mg-tabc] RE: TC diff. bearings Not neccessarily so! the very early TA Diff had a single row ball thrust race at the front of the pinion (a hang-over from MMM designs) but it was soon changed to a double row of balls. these were Ransome & Marles bearings with bronze cages to keep the balls apart, and when they break up (as they all do sooner or later) a whole lot of little "T" shaped pieces fall out (how appropriate!!!). the Moss replacement bearing is a 3305, has steel and/or plastic cage, fewer balls, and will not last as long. THE ideal solution is to fit taper-roller bearings (invented, so I believe, by an American called Timken, but that's another story...) and forget them. I have lost count of the number I have done now, but for those of you who don't want to post your diff. to England, I will let Walter have my setting up and modifications to put in the Tech File. BTW if you really insist on having the orig. brgs, I have a few left. ocTagonally TCRoger

>The bearing closest to the prop shaft flange is supposed to be a double row >bearing. (Item 27 page 80 Moss T type catalog.) If your front bearing is

a

>single row it has been replaced at some time in the cars history. I have

no

>experience to draw on as far as replacing the double row with a single row >bearing. Maybe someone on the TABC net can shed some light on whether this >is an acceptable change. If not, I would order the proper double row >bearing and replace the single one. I am going to copy the TABC group on >this to see if anyone else can help. How about it group? Anyone have any >thoughts on this? >Neil Nelson > I (obviously mistakenly) thought that it was the singe row (closest >to the prop shaft) that was the weak bearing set in the carrier. I >had just put the carrier back in when the threads started on this >quite a number of months ago. At the time, I took everything apart >again after I read the threads (since I had the frame open) and >inspected the single bearing, only to find that a PO had already >installed a new steel set at that position. Haven't progressed much >since that time since my project is in storage pending completion of >move (per job relocation). Suppose I need to go back in again if I >have the original and pull the pinion shaft out to look at the double- >set bearings once I get the TC back? > >Terry V.P. >TC 3452

[m.jablonski@mei.unimelb.edu.au]

> these were Ransome & Marles bearings > with bronze cages to keep the balls apart, and when they break up

(as they

> all do sooner or later) a whole lot of little "T" shaped pieces

fall out ---------------------------------------- My understanding as to why the front pinion bearing fails is that the carrier breaks up due to use of an EP gear oil. The sulphur in the EP additive attacks the bronze in the carrier "de-zincifying" it and making it brittle. It eventually breaks up. I've just pulled the diff out of my car and one of the bronze carriers broke up as the bearing was pulled out. However, the bearing races and balls show no signs of wear. The previous owner had used a standard gearbox oil with EP additives. I think that, if a non-EP oil were to be used, the bearings should last a long time. Penrite advises using their low EP gear oil which they claim will not attack bronze. I intend using it, though I wonder about the effect of even a low level of EP additive. Are there any metallurgists in the list who would care to comment? Mark Jablonski Melbourne Australia TC4820 TC6022

[Roger Furneaux]

hi Neil - no idea, I'm the wrong sort of engineer (did bio-electronics!) but the 3305 has only 9 balls, the 3MDJT25 has 12, so just on surface area of contact alone there is going to be a big difference. the taper rollers of course have a much larger area again. life depends on how much you use it, and I guess most of our cars are travelling a much smaller mileage than when they were new (and probably somebody's only car) so the 3305 will probably last long enough for many people. ocTagonally TCRoger

>Thanks for the info. Since we were talking about a TC the info I passed >along to Terry was correct for his car unless someone has already done the >tapered bearing change. I look forward to your info being posted by Walter. >It really sounds like a better more permanent fix. You stated that the Moss >bearing wouldn't last as long as the original. Since most of the TC's I >have seen dismantled were over 40 years old I wonder just how long the >original bearing lasted and how long it had been in unauthorized pieces. >(Little T's with balls.) Any idea what the expected life of an original >bearing verses the Moss replacement might be? >Neil Nelson >TC 0526 > >-----Original Message----- >From: Roger Furneaux [mailto:Roger.46TC@virgin.net] >Sent: Saturday, June 02, 2001 8:44 AM >To: Neil Nelson >Subject: Re: [mg-tabc] RE: TC diff. bearings > >Not neccessarily so! the very early TA Diff had a single row ball thrust >race at the front of the pinion (a hang-over from MMM designs) but it was >soon changed to a double row of balls. these were Ransome & Marles bearings >with bronze cages to keep the balls apart, and when they break up (as they >all do sooner or later) a whole lot of little "T" shaped pieces fall out >(how appropriate!!!). the Moss replacement bearing is a 3305, has steel >and/or plastic cage, fewer balls, and will not last as long. > >THE ideal solution is to fit taper-roller bearings (invented, so I believe, >by an American called Timken, but that's another story...) and forget them. >I have lost count of the number I have done now, but for those of you who >don't want to post your diff. to England, I will let Walter have my setting >up and modifications to put in the Tech File. BTW if you really insist on >having the orig. brgs, I have a few left. > >ocTagonally > >TCRoger > >>The bearing closest to the prop shaft flange is supposed to be a double row >>bearing. (Item 27 page 80 Moss T type catalog.) If your front bearing is >a >>single row it has been replaced at some time in the cars history. I have >no >>experience to draw on as far as replacing the double row with a single row >>bearing. Maybe someone on the TABC net can shed some light on whether this >>is an acceptable change. If not, I would order the proper double row >>bearing and replace the single one. I am going to copy the TABC group on >>this to see if anyone else can help. How about it group? Anyone have any >>thoughts on this? >>Neil Nelson > >> I (obviously mistakenly) thought that it was the singe row (closest >>to the prop shaft) that was the weak bearing set in the carrier. I >>had just put the carrier back in when the threads started on this >>quite a number of months ago. At the time, I took everything apart >>again after I read the threads (since I had the frame open) and >>inspected the single bearing, only to find that a PO had already >>installed a new steel set at that position. Haven't progressed much >>since that time since my project is in storage pending completion of >>move (per job relocation). Suppose I need to go back in again if I >>have the original and pull the pinion shaft out to look at the double- >>set bearings once I get the TC back? >> >>Terry V.P. >>TC 3452 >