speeder Posted August 2, 2005 Share Posted August 2, 2005 I'm in the final stages of prepping the Porker for road racing. I have an R230 from a Z32 TT installed, and am pretty happy with the performance of the viscuous LSD in my street driving so far. I've heard that the viscous units work fine until they heat up, then start to function as an open diff. Anyone road racing with one of these Z32 units? Impressions? I'm installing a big-a$$ diff cooler with a Tilton pump - The viscous principle is appealing - Its perceived advantages are better durability (no friction materials) and smooth engagement. Quote Link to comment Share on other sites More sharing options...
Guest Battle Pope Posted August 2, 2005 Share Posted August 2, 2005 I don't road race, and don't use an R230, so I can only interject with logic. It would seem that if you'll be keeping the diff cool, then I would think it would keep it from opening under heat... Quote Link to comment Share on other sites More sharing options...
CruxGNZ Posted August 2, 2005 Share Posted August 2, 2005 The viscous principle is appealing - Its perceived advantages are better durability (no friction materials) and smooth engagement. BUT, the viscous differential only works after a wheel starts to spin. Speed, and therefore time is lost while the differential "figures out" that the inside wheel is spinning. From what I've read and heard, a heavier weight oil makes the viscous differential act closer to (but never as efficient as) a mechanical (clutch type) differential. !M! Quote Link to comment Share on other sites More sharing options...
mark Posted August 2, 2005 Share Posted August 2, 2005 The Viscous part of the diff is sealed. You can't change to a different oil. It is filled with some kind of silicone fluid. I have the Q diff in my Z and I have never noticed it doing the one wheel burn out in DE events. I usually run about 30 minute sessions and have seen two stripes thru the turns at the end of the session. I would like some info on the cooler and pump you are using if you don't mind. Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted August 2, 2005 Share Posted August 2, 2005 I too have heard from several people that the viscous diffs can't put up with a lot of abuse... the viscous fluid will shear on a molecular level and eventually the stuff stops doing it's job. I dont know if this is an effect of overheating or other forms of abuse. I know the viscous diff in my Sentra SE-R is all but useless now, no idea how it was treated before I bought it last year.... it's a 14 year old car though but yeah... it might as well be an open diff. Quote Link to comment Share on other sites More sharing options...
speeder Posted August 2, 2005 Author Share Posted August 2, 2005 Mark, I was hoping you would weigh in here - That's good news. BTW, I solved my vibration problem - really stupid - I'll PM you. I ordered this pump from Summit: http://store.summitracing.com/default.asp?Ntt=TIL-40-524&Ntk=KeywordSearch&DDS=1&searchinresults=false&N=0&target=egnsearch.asp&x=29&y=12 I will probably use at least a 10- row Setrab brand cooler (7"X13"X2"), but will get the largest one that will fit in the available space (Front fender side panel behind the louver- I'm building a new tilt front end with 280yz fenders with louvers like my current piece, so there will be extra space in that area- I'll buy the cooler to fit.) The diff coolers I saw used for clutch-type R200 LSDs in SCCA endurance racing were really tiny, like 8"X2"X2", and used this same Tilton pump. I'll use -6 hose and fittings to plumb it. Sounds like I will be fine if I keep it cool! Looks as if the failure modes for the viscous LSD are either leaking of the "mystery fluid" or breakdown? of same. I'll have to study this. Quote Link to comment Share on other sites More sharing options...
RB26powered74zcar Posted August 2, 2005 Share Posted August 2, 2005 I'm watching this Rick. As you know, I tend to hord those R230's and was planing on using one of them sooner or later, I know its a big chunk of change, but have you looked into a CLSD to put in that bad boy?? Anyway, the pump is a very good idea you have there, and I belive it will make the VLSD have a long life... good luck, and keep the info flowing........... joel Quote Link to comment Share on other sites More sharing options...
mark Posted August 2, 2005 Share Posted August 2, 2005 Rick, Thanks for the info. Quote Link to comment Share on other sites More sharing options...
johnc Posted August 2, 2005 Share Posted August 2, 2005 Since the regular diff oil comes in contact with the sealed VLSD it does have a cooling affect. Keeping the diff oil as cool as possible will delay the problems with VLSDs discussed here. Quote Link to comment Share on other sites More sharing options...
Brad-ManQ45 Posted August 2, 2005 Share Posted August 2, 2005 It is my understanding that only in drifting events does the VLSD overheat and go "open". Quote Link to comment Share on other sites More sharing options...
2126 Posted August 2, 2005 Share Posted August 2, 2005 Also, If you plan to mount the cooler in the front grille, that means you will have quit a bit of hose running to and from the diff. With this additional volume of oil you may not require such a large cooler. Just a thought! Quote Link to comment Share on other sites More sharing options...
johnc Posted August 2, 2005 Share Posted August 2, 2005 If both wheels are spinning a differential is not doing much work. The rear end itself might be heating up from the work the ring and pinion is doing but the differential has got it fairly easy. Differentials work the hardest when a engine is at max torque, tires a gripping well, and the car is accelerating around a turn - the sharper the turn the more work the diff has to do. Autocross tends to be the hardest on diffs. Quote Link to comment Share on other sites More sharing options...
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