Antonnick Posted July 13, 2018 Share Posted July 13, 2018 I am thinking that this may be a beneficial modification to do and before the forum revamp I remember seeing some articles on it. The flanges are different for a start I seem to remember. Can anyone direct me to a thread - the search under "differential" does not give a result? Quote Link to comment Share on other sites More sharing options...
glang Posted July 13, 2018 Share Posted July 13, 2018 I searched under 'differential 3.89' and this thread looks interesting: [Sorry, link no longer available] Seems you would have to swop the output quartershafts and input flange from the 4.11 unit onto the 3.89 but that shouldnt be difficult..... Quote Link to comment Share on other sites More sharing options...
Pete Lewis Posted July 13, 2018 Share Posted July 13, 2018 or Canley have this summary https://www.canleyclassics.com/technical-archive/different-differentials Pete Quote Link to comment Share on other sites More sharing options...
glang Posted July 13, 2018 Share Posted July 13, 2018 yes its an interesting article Pete but doesnt explain how to modify each type of diff to allow a swop (in this case changing type D to fit in place of a B)..... Quote Link to comment Share on other sites More sharing options...
RobPearce Posted July 13, 2018 Share Posted July 13, 2018 When we fitted a 3.63 diff on a Herald, we swapped the output stub shafts (four allen bolts each side) and the rear flange of the propshaft (new UJ). The input flange isn't hard to change but on later diffs with the crushable washer it can be tricky to get the right setting. Quote Link to comment Share on other sites More sharing options...
Clive Posted July 14, 2018 Share Posted July 14, 2018 You can only swap the 1/4 shafts if the 4.11 is the later type. There is a useful page on the canley classics site: https://www.canleyclassics.com/technical-archive/different-differentials/ Be careful about over-gearing the car. People have tried 3.27 in 4 cylinder cars as on paper it looks do-able. It just makes the car hopeless. In reality, overdrive is a rather better, if more expensive, solution. Quote Link to comment Share on other sites More sharing options...
Antonnick Posted July 14, 2018 Author Share Posted July 14, 2018 Thankyou everyone for the informations. I like the idea of just swopping the output stub shafts but if this is only possible on later types...how late is late? My 13/60 is 1970 vintage. I can well imagine that a 3,27 would be unworkable but a 3,63 would be nice for the Autobahnen. Looks like a nice winter projekt. Quote Link to comment Share on other sites More sharing options...
glang Posted July 14, 2018 Share Posted July 14, 2018 Your vehicle should have a diff with a serial number starting GE (can be seen stamped on the flat underside surface of the front half) which is the later type and so possible to swop. I would go for 3.89 as this is the ratio used successfully in the Vitesse which has considerably more power and torque than the 4 cylinder. Dont forget that changing the ratio can mean more revs are needed to pull away which is harder on the clutch and worse, having to change down to third on steeper inclines (not to be recommended on our gearboxes). Quote Link to comment Share on other sites More sharing options...
glang Posted July 14, 2018 Share Posted July 14, 2018 oh and the 3.89 is much more readily available and so cheaper. You need one with a serial number starting FD, HC, FH or KD although some of these might only come with 4 stud holes for the spring mounting (later swing spring type axles) which is not ideal. The only difficulty is finding a good one..... Quote Link to comment Share on other sites More sharing options...
Nick Jones Posted July 14, 2018 Share Posted July 14, 2018 3.89 diff is fine for a 13/60 herald, even with OD. Only 5% different! 3.63 ~ 12% different and still a fairly realistic swap, though OD as well might be a bit to much for the standard engine. If the diff in the car is original (ie 1970) then you should be able to swap the quarter shafts. However, for the input shaft I'd suggest changing the UJ flange on the end of the propshaft rather than trying to change the input shaft flange as I'm pretty sure the splines are different.... Nick Quote Link to comment Share on other sites More sharing options...
RobPearce Posted July 14, 2018 Share Posted July 14, 2018 Quoted from Nick Jones- However, for the input shaft I'd suggest changing the UJ flange on the end of the propshaft rather than trying to change the input shaft flange as I'm pretty sure the splines are different.... I'm not sure - my GT6 was, at one time, fitted with a GE-prefix 4.11 diff with the larger input flange. I did wonder whether it was merely a GT6 diff in a Herald case but I measured the ratio and it was definitely a 4.11 I'd agree on doing the propshaft UJ flange, though, because it's easier and doesn't involve worries about pre-load settings. Quote Link to comment Share on other sites More sharing options...
glang Posted July 14, 2018 Share Posted July 14, 2018 Would any of you guys have a problem using a 4 fixing diff on a non swing spring car? Quote Link to comment Share on other sites More sharing options...
RobPearce Posted July 14, 2018 Share Posted July 14, 2018 Not really. That Herald I mentioned earlier was a four-fixing Spitfire diff on a non-swing estate. Quote Link to comment Share on other sites More sharing options...
marktheherald Posted July 14, 2018 Share Posted July 14, 2018 Both my Estate and Midge run 4 hole diffs.. 3.89 in the estate, 3.63 in the Midge. Quote Link to comment Share on other sites More sharing options...
glang Posted July 14, 2018 Share Posted July 14, 2018 Thanks, I never understood why Triumph designed them with the 6 holes in the first place..... Quote Link to comment Share on other sites More sharing options...
Antonnick Posted January 22, 2019 Author Share Posted January 22, 2019 I have now got a 3,63 ready to install. Quote Link to comment Share on other sites More sharing options...
Jonny-Jimbo Posted January 22, 2019 Share Posted January 22, 2019 Interesting talk this - people often write about bits being original to the car etc, but it can be hard to tell any real difference between 5, 10, 20 or 50 years of grime under a car.Last summer I was replacing the diff seals for a customer's 13/60, which looked mostly untouched, but when I tried to replace the circlips etc I found that it in fact had the smaller diameter quarter shafts in it.For all we know, it may well have left the factory like it and they just built a batch of cars with whatever was lying around the factory! Quote Link to comment Share on other sites More sharing options...
glang Posted January 22, 2019 Share Posted January 22, 2019 Quoted from Antonnick- I have now got a 3,63 ready to install. right now comes the fun part! Its not a bad job apart from lowering and lifting the diff into place. Unless youve got access to a car lift it means jacking the car up and doing everything laying on your back - Ive done it just manhandling the diff but you have to be careful so maybe best with a hydraulic jack and even then a lot of care and possibly a helper is needed..... Quote Link to comment Share on other sites More sharing options...
Antonnick Posted January 23, 2019 Author Share Posted January 23, 2019 We have a scissor lift in the garage but due to the low height, the car can only be raised about 70cm - it is usually enough. But it is very cold at the moment, down to -13° at night. Quote Link to comment Share on other sites More sharing options...
glang Posted January 23, 2019 Share Posted January 23, 2019 yes that should be ok as if you raise the car up too much its difficult to lift the diff up the same amount. Remember its not just lifting the diff but holding it there a while to put the fixing bolts in place.... And yes you cant concentrate when its too cold so youre better off indoors in the warm planning the job! Quote Link to comment Share on other sites More sharing options...
Steve P Posted January 27, 2019 Share Posted January 27, 2019 I`ve had a 3:63 in my 13/60 FH 1300 engined Herald for 9 years now,including a single rail o/d box.I think i changed the prop as the o/d required it anyway (shorter).Always found it fine to drive with easier cruising at 70 no problem,the only thing it won`t do is go up a decent hill in o/d top.Did the RBRR in it no issues. About to put a new 1500 in though for more fun..+Cv conversion. S Quote Link to comment Share on other sites More sharing options...
Antonnick Posted January 28, 2019 Author Share Posted January 28, 2019 That is good to know and I am working on the change now. I do not have an overdrive gearbox though. At the moment have only taken the propshaft off. This will be derusted, treated and painted gloss black. Whilst the rear diff is off, I will inspect and renew as necessary the rear suspension. Probably new shock absorbers and perhaps even the spring. It looks solid but very rusty. Quote Link to comment Share on other sites More sharing options...
glang Posted January 28, 2019 Share Posted January 28, 2019 yes its a good time of year to tackle that job. Will you be installing a lowering block between the diff and spring? Its something that I want to do on my Vitesse as it sits quite high at the back which gives it a tendency to oversteer. The blocks come in different thicknesses but I think the thinnest at 1/2" will be sufficient in my case.... Quote Link to comment Share on other sites More sharing options...
Antonnick Posted January 29, 2019 Author Share Posted January 29, 2019 You think so? We have 50cm of snow outside and the temperatures have been minus for at least two weeks. I put thick clothes on, a hot water bottle to warm the hands periodically but only do a couple of hours a day. But hopefully the car will be ready for when it gets warmer and make the effort worth while. I have not considered lowering the suspension. I think this will be too much and not really necessary for the way I drive. Quote Link to comment Share on other sites More sharing options...
Antonnick Posted February 21, 2019 Author Share Posted February 21, 2019 I may have a problem to solve. To replace and install a new flange to the rear axle in order to join with the new 3,63 diff, we have taken off the complete rear suspension. This means there is access to the areas which need some rust tratment and the rear spring can be removed and checked. We did try to remove a "bolt" from the bottom of the vertical link and in doing so the thread has been damaged. It seems this is not a bolt at all but part of the vertical link itself - the extended shaft holds the lower part of the shock absorber on. I am thinking that the thread can be repaired using a 7/16 UNF thread cutter but if this fails then a new vertical link will be required - 😭 yes? Quote Link to comment Share on other sites More sharing options...
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