JBRoberts Posted July 22, 2012 Report Share Posted July 22, 2012 Hi all: I'm working my way through the mechanicals as part of my ground up restoration and am cureently on the rear axle. Couple quick questions: 1) Are there any simple checks to do (without the use of special tools) to see what might be good or bad ? 2) I plan on replacing all the seals and halfshaft bearings as precautionary. Should I also replace anything else ? 3) Also, I need a bit of education on how it works. When I rotate the input shaft (connects to the prop shaft) both axles rotate but when I grab hold of one to put some force on it, the input shaft keeps turning ? I was thinking this was a solid type drive and if your turning the input shaft then you would not be able to stop the half shafts from turning ??? Thanks for any thoughts/comments JB Quote Link to post Share on other sites
RogerH Posted July 22, 2012 Report Share Posted July 22, 2012 Hi JB, the diff allows the rear wheels to be driven in a straight line. However when you come to a corner the outer wheel will want to rotate quicker than the inner wheel. If the diff was fixed, as you were expecting, then all hell would break loose. You may even find getting around the corner quite problematic. So the diff is designed to allow the engine to drive the rear wheels in either straight line or corners. The downside of this is that you are actually only drivong one wheel at a time. Shouls a wheel start to slip (snow/ice etc) then you will lose forward drive as the wheel in good contact will have no drive. There is a Limited Slip Diff (LSD) that allows good straight traction and cornering ability; but for general use they are not required. The actual mechanics of the diff is quite fascinating as it incorporates various parts of the universe - Sun, Planets and probably a few asteroids. If you google Differential workings all will be revealed. Roger Quote Link to post Share on other sites
AlanT Posted July 22, 2012 Report Share Posted July 22, 2012 Be careful not to do more harm than good with these. Dont get any grit in it whlie you are doing the seals or you will mess it up. Drain the oil on a hot day. Catch it in a white container and look for metal flakes, chips off teeth etc, Make sure you have the right oil to put back in. Dont reuse the oil. Ensure that the breather hole at the top is free from grit and is open. This has a kind of loose pin that seals it after a fashion. Hold BOTH output shafts and waggle the input shaft. There will be backlash, perhaps 1/8 in either way. Hold one output and the input. Backlash check is similar. Do this at a number of positions. Backlash should be about the same everywhere. Push/pull each shaft to check end float. Should all feel about the same. Will run 200K without any trouble, usually! Al. Quote Link to post Share on other sites
JBRoberts Posted July 22, 2012 Author Report Share Posted July 22, 2012 Thanks fellas...this is very helpful and good to go now JB Quote Link to post Share on other sites
Kiwifrog Posted July 22, 2012 Report Share Posted July 22, 2012 This is the best explanation I have ever seen on how a diff works. It was posted here a couple of months ago Quote Link to post Share on other sites
BlueTR3A-5EKT Posted July 24, 2012 Report Share Posted July 24, 2012 (edited) Firstly, get a factory service manual and have a read through the relevant section. If this is a TR4 not TR4A read the threads on this forum regarding rear hub removal before getting down and dirty. Unless you are awfully lucky or equipped with the right hub puller you will bend the drive flange on the rear hub trying to extract it from the half shaft. - it's open your wallet time then. There are two seals and one bearing in each rear hub/axle tube end that can be renewed. You will have to use a dial indicator to get the axle shaft end float across the axle correct - fiddly and time consuming but important. There is one seal on the differential input where the prop shaft attaches this is a most common seal to leak and is replaceable. Remove prop-shaft out of the way, remove split pin, remove big nut, pull off drive flange, catch oil, spend 1/2hr levering/destroying the seal to get it out the housing. Fit the new seal the right way round, fit flange and re-torque the drive flange nut correctly. Re split pin. Refill the axle with correct Hypoy GL4 EP 90 oil. Do not use GL5 oil, it apparently eats the brassy washers that are in the axle. As Al says clear out the breather. If it is a TR4 you will have a 1/8 diameter hole in the breather on the top of the axle left side. Wire brush round it. remove, clear out hole and refit. Poking a slug of gritty oil into the axle is not the best engineering practise. (is this a verb or a noun? - discuss) The blocked breather is often the cause of oil seal seepage. To repair the inside of the axle properly and comfortably it would be best to remove it from the car - no doubt someone reading this has replaced a crown wheel and pinion without axle removal, using a spade handle and rusty 6 inch nail they found in the ditch next to where their car failed..... Inside the axle there is a lot you can do but will need bearing removers, dial indicator, micrometer, torque wrench and patience. Plus of course access to spares. on special tools - I have only ever used a differential case spreader once and that was not on a TR. A pinion pre-load gauge is very useful but can be improvised with a spring balance and length of metal bolted to the flange. Cheers Peter W Edited July 24, 2012 by BlueTR3A-5EKT Quote Link to post Share on other sites
Peter Pan Posted July 31, 2012 Report Share Posted July 31, 2012 Hi Good U.S of A advice If it aint bust dont fix it Peter Pan Quote Link to post Share on other sites
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