B gearbox/LSD questions

Bringing this back for some advice on which fluid I should be using...

Finally got it all installed and with a Competition Clutch stage 4 and took for a test today. I know to expect some clunking etc from the diff but it's pretty severe, way more than I expected. I'm not just talking carpark speeds either, even a bit of clunking going around corners at 60kmh.

Driveshafts weren't changed and are pretty new and I have brand new 62a Hasport mounts. It only does it under load/acceleration so I'm pretty sure I can rule out anything other than the diff.

Currently running OEM MTF with a dash of the Ford friction modifier (40ml) which didn't seem to make any difference. Not sure how much to put in as it's really hard to get good answers from Google etc! The car is almost undriveable at low speeds so need some options here.

I am also running a clutch LSD (cusco) in my B series transmission. I have also tried the oil combo you are using.

When I ran OEM oil with friction mod additive the diff clunked like crazy with a little bit of friction mod but with more friction mod the synchros slipped.

I have found the best combo that works for reducing clunking without compromising the synchros performance is Penrite Pro Gear 75w-85 (GL4) and a small tube of Nulon G70. Pour the G70 into the 2.5L bottle of Pro Gear and shake it up to premix, then drop it straight in.

Just a note tho, diff additives shouldn't be required if the preload on the diff is set low. If it's clunking too much the preload is probably high. Adding friction modifier creates more slip on the plates but also has the same effect on your synchros.

Hope this helped. :thumbsup:

I'm a bit hazy now, did we ever figure out what the diff was? Depending on clutch settings they can be pretty noisy but not to the extent you're describing.I would have cleaned it thoroughly in a quick dry solvent for final clean, which can "dry" the plates out a bit and it can take a while for the oil and friction modifier to get into the clutch packs. Oil selection can be tricky with a clutch LSD in a synchro box. I like the ULX-110 75w90 gear oil for this. It seems to shut most clutch LSDs up (to an extent). I've heard good things about the Penrite pro gear too, but have not personally used it. Let me know if I can help/test drive etc.

Cheers Sam, hopefully I can figure out an oil combo that works before I need to bring it down. I think we decided it was an MFactory LSD in the end.
What you are saying about the plates 'drying' makes sense, they feel like they are sticking and then suddenly give, how long would you expect them to lube up? I've only done about 10km in a few different trips so far

I reckon I'll try another 40ml of the modifier and then the whole bottle if that doesn't work, then move on to a different oil as suggested.

Sorry to butt in. I did a bunch of googling and mineral oil is recommended for clutch type lsds. Ive recently tried penrite 80w90 gear oil with one small tube of nulon g70. Cold is pretty meh. But once warm/hot omg. Its like butter and no chatter/horrible clunks/weird looks from people. Its hard to find a balance between cold shifting and clutch noise. But I feel like this option is doable. 80w90 penrite gear oil is like $20/25 and the additive is under $15? So all up 40 bucks... Oem will still cost more. But if I could run oem I would, that stuff is great.

OEM is mineral based though, so I think Mark is on the right track. The ULX is full mineral based with their own friction modifier package that works well. I sell it for $20/L or $90 for 5L so same ballpark price.

Mark you need to run it more than that to allow the oil to get in. The design of these diffs restricts (deliberately) the amount of oil going into the clutch packs, and it can take a lot longer to get back to normal - I would have thought 100km of cornering or so. Go easy on the friction modifier as the synchros will be effected and will prematurely fail if you load them up too much with the slippery stuff. My thoughts are it needs more driving rather than tinkering with the oil blends at this stage.

Cheers for the advice. It's a worry driving it, feels like something is going to break! I am certain it's the diff though and nothing else so I guess if it does break it was buggered anyway... Lol.

As I said it does feel like its loading up then giving way so will keep going as you suggest

Ok so an update.. Thankfully a few supermarkets don't open till 11am on a Sunday in SA so I went down to the local Coles carpark to do some figure 8s. Got a few weird looks from people driving in and an old couple sat and watched me for about 10mins, probably thought I was mad.

She was clunking severely just like before initially but I just kept going for about 10 mins and then went for a drive on some slightly winding roads for about 15 mins. Came back to the carpark and as I turned in it was still clunking but when I started doing the 8s it rapidly lessened and after 5mins I couldn't get it to clunk at all. Did all this again and exactly the same thing happened. Then I went for a drive to mt barker and lots of tight low speed turns. It's a lot better and the clunks are a lot less, still doing it mainly on roundabouts and similar turns but 90degree intersections it doesn't really do it at all.

I reckon I've done about 60kms today in about 2 hrs total including stopped time. I'm thinking everything is ok and I just need to keep driving and bedding it in. The clutch still has about 500km to bed in too before I really get to test things out.

Still intending to play around with oils in the future but it seems ok for now.



In other news, my dodgy VSS setup works perfectly. Calibrated it using a gps speedo on the iPhone in the work car then in the teg and it's spot on surprisingly,

Hey mooshie just following up how the oem plus ford friction modifier is going?

The penrite 80w90 when cold is so bad it even crunches. Even actually coming out of gear is difficult. So I decided to try penrite 75w80. Initially ok cold and hot. But after a day of driving It started clunking again I guess the 80w90 finally came off the clutch packs, that stuff is so thick it doesnt even drain out of the box quickly. Chez you mentioned ulx110 75w90 which I can't seem to find, only the 80w90 comes up on their site, can you confirm?

There are very few if any 75w90 mineral oils. May have to settle for a semi syn or go oem mtf with ford modifier as mooshie did. Or even try 75w85 penrite pro gear oil however that is fully synthetic from memory.

Quote:

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Originally Posted by ceekay101

Hey mooshie just following up how the oem plus ford friction modifier is going?

The penrite 80w90 when cold is so bad it even crunches. Even actually coming out of gear is difficult. So I decided to try penrite 75w80. Initially ok cold and hot. But after a day of driving It started clunking again I guess the 80w90 finally came off the clutch packs, that stuff is so thick it doesnt even drain out of the box quickly. Chez you mentioned ulx110 75w90 which I can't seem to find, only the 80w90 comes up on their site, can you confirm?

There are very few if any 75w90 mineral oils. May have to settle for a semi syn or go oem mtf with ford modifier as mooshie did. Or even try 75w85 penrite pro gear oil however that is fully synthetic from memory.

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As I mentioned I am using this with 125ml of G70 for street and track with my ITR box and Cusco Clutch Diff, it's fine. Works great and doesn't mess with your synchros.

Haven't had a chance to drive the car much, prob only put about another 80k on it last weekend- was still clunking a lot when cold but as the box warmed up it got much better. I'm finding that on really tight turns such as carparks it's fine but when I go around some big right angle intersections and roundabouts where it's sort of 3/4 lock I get clunking. Bit weird.

Fkn car has picked up a miss at very light throttle now from somewhere- fine at anything more than just touching the pedal in any gear and any revs but stutters like crazy just cruising. Good excuse to finally swap in my Edelbrock intake mani and get a retune I think. Until then I won't be playing much, but I will try some more of the modifier, so far I've only put about 40ml in there. I would think this G70 is similar stuff and if others are using the full 125ml tube I think I still have some leeway.

Quote:

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Originally Posted by Super-DA9

As I mentioned I am using this with 125ml of G70 for street and track with my ITR box and Cusco Clutch Diff, it's fine. Works great and doesn't mess with your synchros.

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Yeh I may go up a smidge (to 75w80). The 75w80 is pretty good for shifting. The clunking isnt to bad. Much worse when i first tried mtf but i may have also bed in the lsd. My only problem with the pro gear is that its fully synthetic, for a clutch type a mineral oil is best. But I may have to.

Quote:

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Originally Posted by mooshie

Haven't had a chance to drive the car much, prob only put about another 80k on it last weekend- was still clunking a lot when cold but as the box warmed up it got much better. I'm finding that on really tight turns such as carparks it's fine but when I go around some big right angle intersections and roundabouts where it's sort of 3/4 lock I get clunking. Bit weird.

Fkn car has picked up a miss at very light throttle now from somewhere- fine at anything more than just touching the pedal in any gear and any revs but stutters like crazy just cruising. Good excuse to finally swap in my Edelbrock intake mani and get a retune I think. Until then I won't be playing much, but I will try some more of the modifier, so far I've only put about 40ml in there. I would think this G70 is similar stuff and if others are using the full 125ml tube I think I still have some leeway.

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Light throttle id check plugs and leads. I dont know if g70 and gm modifier are the same? I use the g70 for shifting unsure if it helps/affects the clutch lsd. Either way keep us up to date with your lsd progress.