Wilfried Posted May 3, 2015 Report Share Posted May 3, 2015 The rear axle on my TR4A has to my surprise no drain plug. On all drawings in the catalogue there is a drain plug shown. I guess I have to remove the rear cover assembly to get the old oil out. Is this current practice on the US TR4A? Wilfried Quote Link to post Share on other sites
monty Posted May 3, 2015 Report Share Posted May 3, 2015 The rear axle on my TR4A has to my surprise no drain plug. On all drawings in the catalogue there is a drain plug shown. I guess I have to remove the rear cover assembly to get the old oil out. Is this current practice on the US TR4A? Wilfried Yes Wilfried, the TR4 sensibly had a drain plug but they used a different diff. casing on the 4A with no drain plug, for some strange reason. I had to put in a new oil seal a few months ago so put new oil in the unit when it was off the bench, along with new bushes all round. If just draining the oil it would have been a pain! Cheers. Quote Link to post Share on other sites
AlanT Posted May 3, 2015 Report Share Posted May 3, 2015 More modern and saved loads of money! Quote Link to post Share on other sites
Motorsport Mickey Posted May 3, 2015 Report Share Posted May 3, 2015 Just about the start of "sealed for life" units in general manufacturing, they thought all you'd do is top it up. Mick Richards Quote Link to post Share on other sites
littlejim Posted May 3, 2015 Report Share Posted May 3, 2015 You can get 'oil suck out' guns that look like a grease gun. You can put oil in with them too. Quote Link to post Share on other sites
dingle Posted May 4, 2015 Report Share Posted May 4, 2015 It is quite common to add a drain plug when the diff is removed for seals or whatever. There is a round boss on the bottom of the diff just made for the plug location. The plug is 3/8' tapered pipe, same as the one used on the engine&trans. A magnetic plug would be my choice. Maybe Triumph thought the diff would leak anyway, so a few cents could be saved by eliminating the plug. Berry Quote Link to post Share on other sites
TriumphV8 Posted May 4, 2015 Report Share Posted May 4, 2015 Drilled hole in the appropiate place and locked it with a sender for oil temperature. As I had the oil temp gauge for my engine oil of the V8 already I added a switch and it was a lot of fun to see the oil temp of the diff. Quote Link to post Share on other sites
Wilfried Posted May 4, 2015 Author Report Share Posted May 4, 2015 Thanks for all your replies and suggestions! I will remove the rear cover, so I can also check if the play on both sides of the "thrust button" are equal. (I had to shim 0.1mm on the right side, and did not check then). Wilfried Quote Link to post Share on other sites
Wilfried Posted May 6, 2015 Author Report Share Posted May 6, 2015 Drilled hole in the appropiate place and locked it with a sender for oil temperature. As I had the oil temp gauge for my engine oil of the V8 already I added a switch and it was a lot of fun to see the oil temp of the diff. What was the highest temperature you measured on the diff oil? My guess would be that it is only a few degrees above ambient, unless you use the brakes intensively? Wilfried Quote Link to post Share on other sites
RogerH Posted May 6, 2015 Report Share Posted May 6, 2015 Hi Wilfried, I think the brakes would have no effect on the diff temp. I also think the temp would be quite high. There is a lot of mincing going on with that oil. Roger Quote Link to post Share on other sites
TriumphV8 Posted May 6, 2015 Report Share Posted May 6, 2015 The diff dislikes high speed on the highway. If you let the temp stabilize what needs some minutes constant speed I would expect about 30 degrees above speed in KM/h As 170 degrees was the limit on the gauge I can only guess but it was far beyond 200 degrees. So when we go to Italy down the highway the temp is all the time around the limit of the gauge unless we go topdown on warm weather. Quote Link to post Share on other sites
stillp Posted May 6, 2015 Report Share Posted May 6, 2015 On all drawings in the catalogue there is a drain plug shown. Wilfried, which catalogues are you talking about? There isn't one shown in my Stanpart catalogue. Pete Quote Link to post Share on other sites
Wilfried Posted May 9, 2015 Author Report Share Posted May 9, 2015 Wilfried, which catalogues are you talking about? There isn't one shown in my Stanpart catalogue. Pete I was referring to the catalogue in rimmerbros.co.uk . They call it the "solid Girling type" and the plug is Nr. 71. Wilfried Quote Link to post Share on other sites
Wilfried Posted May 9, 2015 Author Report Share Posted May 9, 2015 The diff dislikes high speed on the highway. If you let the temp stabilize what needs some minutes constant speed I would expect about 30 degrees above speed in KM/h As 170 degrees was the limit on the gauge I can only guess but it was far beyond 200 degrees. So when we go to Italy down the highway the temp is all the time around the limit of the gauge unless we go topdown on warm weather. This information is most interesting! On my last journey, the diff was becoming quite noisy. I was afraid that oil was missing. But this was not the case. I read the workshop manual regarding the rear axle and learned that: Both axles are pushed into the diff. In the center there is a "thrust button". The axial play of the axles should be about 0.1mm, adjustable with shims. The button should be laterally free, i.e. have the same play left and right. As I had to remove the rear cover assembly, I could see the button..and the missing play at the right side of the button. I added 0.5mm play at the right side: the diff is now running normally quiet! Which brought me to the following consideration: when running the car, the heat is mostly produced at the diff. The diff and the two axles get hot, and the heat is the dissipated by the axle hosing. Therefore the axles are hotter than the housing. They expand more than the housing. With a difference of 16 deg F between axles and housing, the play of 0.1mm is already eliminated! At high speed the temp. difference could very well be much higher than 16 deg. This means that the rollerbearings will come under high stress. And if there is no play on one side of the button, the diff will suffer also. With the play of 0.5mm this will not happen. I wonder, why the factory advised such little play. What is the disadvantage of 0.5mm? Wilfried Quote Link to post Share on other sites
stillp Posted May 10, 2015 Report Share Posted May 10, 2015 I was referring to the catalogue in rimmerbros.co.uk . They call it the "solid Girling type" and the plug is Nr. 71. Wilfried Oh, sorry, I had assumed it was IRS. Pete Quote Link to post Share on other sites
TriumphV8 Posted May 12, 2015 Report Share Posted May 12, 2015 Just noticed it is not an IRS? Thought TR4A is always IRS except some rare US examples? All my data referring temp are for the IRS, the TR4 stay much cooler due to the axle tubes on both sides! Quote Link to post Share on other sites
stuart Posted May 13, 2015 Report Share Posted May 13, 2015 Just noticed it is not an IRS? Thought TR4A is always IRS except some rare US examples? All my data referring temp are for the IRS, the TR4 stay much cooler due to the axle tubes on both sides! Not that rare for US cars, quite a few have come back over here now (including mine.) Stuart. Quote Link to post Share on other sites
Wilfried Posted May 14, 2015 Author Report Share Posted May 14, 2015 My car came from the USA. The papers, the batch on the rear all say it is TR4A. Its chassis number is STC 65 CT 35370, which means it is a TR4. The chassis is the TR4 type, not th belly type. It is not IRS. It has no sidelamps. My conclusion: it is a normal TR4 which has been sold in the USA as TR4A. Wilfried Quote Link to post Share on other sites
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