Gpro Posted January 29, 2017 Share Posted January 29, 2017 Hi guys, It looks like I broke my B03B (6spd) diff yesterday at standstill whilst dumping the clutch at high RPM. It's making weird noises and the car won't drive (just a tiny bit on even ground). Before I go out and buy a new LSD, does anyone know of any common issues with the big case diffs? Additionally, I found a stock LSD torsen 8.7" replacement for £500. Does anyone know if I can get an upgraded one for under £1,000? Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted January 29, 2017 Share Posted January 29, 2017 Hi guys, It looks like I broke my B03B (6spd) diff yesterday at standstill whilst dumping the clutch at high RPM. It's making weird noises and the car won't drive (just a tiny bit on even ground). Before I go out and buy a new LSD, does anyone know of any common issues with the big case diffs? Additionally, I found a stock LSD torsen 8.7" replacement for £500. Does anyone know if I can get an upgraded one for under £1,000? The commonest reason for differential or crown wheel and pinion failure is dumping the clutch at high RPM. You are in good company Quote Link to comment Share on other sites More sharing options...
j_jza80 Posted January 29, 2017 Share Posted January 29, 2017 The commonest reason for differential or crown wheel and pinion failure is dumping the clutch at high RPM. You are in good company Presumably it will be the crown wheel and/ or pinion that has been damaged? In which case, an aftermarket diff (internal) won't contain the parts needed to fix it. Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted January 29, 2017 Share Posted January 29, 2017 Could well be the planetary gears that have failed, splines stripped, blah blah. Would need a good coat of looking at. Quote Link to comment Share on other sites More sharing options...
Guest Sprog Posted January 29, 2017 Share Posted January 29, 2017 I've had my big case diff b03b took off cause it was making a lot of noise, after closer inspection the pinion wheel has lost some teeth. So now sitting on my garage floor waiting to be fixed one day. Quote Link to comment Share on other sites More sharing options...
Frank Bullitt Posted January 29, 2017 Share Posted January 29, 2017 Ring & Pinion for MK IV Supra Quote Link to comment Share on other sites More sharing options...
Gpro Posted January 29, 2017 Author Share Posted January 29, 2017 hmm, I guess I will wait until I get the diff off and take a look at what's wrong before buying anything. I hope it won't cost more than a grand to fix. Quote Link to comment Share on other sites More sharing options...
Supra-love Posted January 29, 2017 Share Posted January 29, 2017 hmm, I guess I will wait until I get the diff off and take a look at what's wrong before buying anything. I hope it won't cost more than a grand to fix. I work as an engineer building gear boxes and diffs for f1, rally and touring etc, let me now what you need if I can help I will mate. Quote Link to comment Share on other sites More sharing options...
a98pmalcolm Posted January 29, 2017 Share Posted January 29, 2017 My diff locked up a week before xmas and all my parts are on order. Hi have been stressed to the eyeballs with it as my pinion was damaged in the process. The Jspec pinion is discontinued so I have had to order a US spec one, still £750 from Amayama. Also an Os Giken is ordered and a new prop shaft as that snapped in the process. Skint is not the word... I will be making a post with the pics of the damage and rebuild once completed. Quote Link to comment Share on other sites More sharing options...
Gpro Posted January 29, 2017 Author Share Posted January 29, 2017 I work as an engineer building gear boxes and diffs for f1, rally and touring etc, let me now what you need if I can help I will mate. Thanks mate, I will hopefully get the diff of on the weekend and post images of the damage. Quote Link to comment Share on other sites More sharing options...
Gpro Posted March 17, 2017 Author Share Posted March 17, 2017 I've been too busy to even take a look at the car. Managed to get under it today and noticed this. The axle bracket is cracked. Not sure if anything inside the diff is damaged as well. Any thoughts? Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted March 17, 2017 Share Posted March 17, 2017 Something has pushed the crown wheel sideways with HUGE force, probably a tooth or three off the crown wheel or the pinion. CWP scrap, case needs bead blasting and crack testing, quite possibly it's scrap too Drag race start? Quote Link to comment Share on other sites More sharing options...
Gpro Posted March 18, 2017 Author Share Posted March 18, 2017 Something has pushed the crown wheel sideways with HUGE force, probably a tooth or three off the crown wheel or the pinion. CWP scrap, case needs bead blasting and crack testing, quite possibly it's scrap too Drag race start? Yeah it was a high rpm launch that broke it. Quick question, I have a spare NA small open diff. Could I just buy a cusco LSD and put it in, or does it have to be an LSD diff to replace the torsen with a cusco one? (I understand my gear ratios will be significantly different). Quote Link to comment Share on other sites More sharing options...
Frank Bullitt Posted March 18, 2017 Share Posted March 18, 2017 The only LSD you should consider fitting is OS Giken or if you are lucky to find one TRD but since the latter is discontinued expect to pay stupid prices for one. You could fit the small case with an aftermarket LSD and change the ratio but if you give it the same abuse as you have given this one I wouldn't expect it to last. Quote Link to comment Share on other sites More sharing options...
Gpro Posted March 18, 2017 Author Share Posted March 18, 2017 The only LSD you should consider fitting is OS Giken or if you are lucky to find one TRD but since the latter is discontinued expect to pay stupid prices for one. You could fit the small case with an aftermarket LSD and change the ratio but if you give it the same abuse as you have given this one I wouldn't expect it to last. I'm not planning on doing anymore launches so it should technically last, I hope!. How would I go about changing the final gear ratio? Can't find anything online on it or where to purchase different gears. Quote Link to comment Share on other sites More sharing options...
Frank Bullitt Posted March 18, 2017 Share Posted March 18, 2017 I'm not planning on doing anymore launches so it should technically last, I hope!. How would I go about changing the final gear ratio? Can't find anything online on it or where to purchase different gears. You would need to order the parts from Toyota, you want a 3.266:1 ratio for a small case which is part number 41201-19645. Expect the price to be eye watering or look for someone selling an A03B diff then you would have the OEM LSD and correct ratio for a manual car. Quote Link to comment Share on other sites More sharing options...
j_jza80 Posted March 18, 2017 Share Posted March 18, 2017 Yeah it was a high rpm launch that broke it. Quick question, I have a spare NA small open diff. Could I just buy a cusco LSD and put it in, or does it have to be an LSD diff to replace the torsen with a cusco one? (I understand my gear ratios will be significantly different). You'd be best sourcing a 98- ls400 3.2 diff, small case but with a 3.2 ratio which is much nearer to the tt6 ratio than the n.a. supra ones. Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted March 18, 2017 Share Posted March 18, 2017 There are 2 sizes of crown wheel.large and small, and two sizes of aftermarket LSD's, large and small. Match the sizes and you should be OK. Cusco LSD's are quite horrible, grabby, juddery and unkind to the transmission and civilised driving however. TRD or Giken are far better. Quote Link to comment Share on other sites More sharing options...
Gpro Posted March 18, 2017 Author Share Posted March 18, 2017 There are 2 sizes of crown wheel.large and small, and two sizes of aftermarket LSD's, large and small. Match the sizes and you should be OK. Cusco LSD's are quite horrible, grabby, juddery and unkind to the transmission and civilised driving however. TRD or Giken are far better. I wouldn't mind getting the OS Giken LSD, but can't justify buying that for my spare small diff (NA open) which has the wrong gear ratios. Will try take out my current diff to assest the damage. I fit's a write off, I will be on a look out for a TT6 small LSD diff. Quote Link to comment Share on other sites More sharing options...
Gpro Posted March 19, 2017 Author Share Posted March 19, 2017 Got the diff off today and upon a quick inspection it doesn't seem to look that bad. Everything seems to be in mint condition. I believe the axle stud has failed. I haven't been able to remove this, I'm presumming I need a puller? I'm hoping that's all that needs replacing. See pics below. Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted March 19, 2017 Share Posted March 19, 2017 Axle stud?? What's an axle stud?? Quote Link to comment Share on other sites More sharing options...
Frank Bullitt Posted March 19, 2017 Share Posted March 19, 2017 Pull the axles stubs out. They are pressed out by threading the axle bolts through the axle stubs into the diff case. Be carefull and thread them a little at a time in order to push them out straight. Remove the 8 bolts on each side around where the axle stubs were fitted. After the bolts are out gently pry the differential carriers, start with the passenger side carrier so the LSD will not fall out. Again, be carefull to pull them out straight. There is an o-ring seal around these. Support the LSD with your hand and pry the drivers side carrier out. Quote Link to comment Share on other sites More sharing options...
Gpro Posted March 19, 2017 Author Share Posted March 19, 2017 Pull the axles stubs out. They are pressed out by threading the axle bolts through the axle stubs into the diff case. Be carefull and thread them a little at a time in order to push them out straight. Remove the 8 bolts on each side around where the axle stubs were fitted. After the bolts are out gently pry the differential carriers, start with the passenger side carrier so the LSD will not fall out. Again, be carefull to pull them out straight. There is an o-ring seal around these. Support the LSD with your hand and pry the drivers side carrier out. When you say pull the axle stubs out, do you mean by hand? Yes I've taken the 8 bolts our and can see the o-ring seal. Quote Link to comment Share on other sites More sharing options...
Frank Bullitt Posted March 19, 2017 Share Posted March 19, 2017 When you say pull the axle stubs out, do you mean by hand? Yes I've taken the 8 bolts our and can see the o-ring seal. They are pressed out by threading the axle bolts through the axle stubs into the diff case. Can you pop up some pictures of the side of the diff so we can see what you have done so far. Quote Link to comment Share on other sites More sharing options...
Gpro Posted March 25, 2017 Author Share Posted March 25, 2017 Managed to get it all apart today. Not sure how I managed to do this, but the LSD is snapped in half, also when I drained the oil, it wasn't 1.8+ litres so i'm presumming I was running low. Everything else looks fine, so I'm hoping all I need is just a new LSD and I'm back on the road! Quote Link to comment Share on other sites More sharing options...
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