Limited Slip install experiences

[zhaireszhp]

This is my next project, probably going aftermarket helical setup unless I find a great deal on an M3 rear end in next few months.

But I've been wondering those who have went aftermarket, have you all bought reconditioned pumpkins with lsd already installed via like diffsonline.com or did you buy the LSD separately and get it installed to your differential carrier by a local shop.

Have seen some folks on the internet DIY e90 e87 wavetracs into their carriers and imagine its similar, I'd honestly think about DIYing as it honestly doesn't look incredibly complex but it seems hard to find internal parts, such as races, if something were to break while dissembling the open diff.

I had asked a bmw shop that I saw advertised lsd differential services but the owner made it seem like the extent of their LSD installation is installing pumpkins. which I can frankly do in the garage. So I'm curious what most do, the pumpkin price seems steep when I know what the individual unit costs, but is that the most common way folks get these in their cars?

[sillieidiot]

I haven't done it yet. But my plan was to buy a used pumpkin in the ratio I want, then refurbish and install the LSD into that. then swap it out. Since used diffs are fairly cheap, you still save overall. Plus if for some reason I mess up, I have the stock diff to swap back to keep my downtime at a minimum.

[GeorgeH]

If you are not experienced in setting up differentials or already have the tools then I would suggest 1 of 2 options.
1. Throw a wavetrac in your existing final drive assembly and call it a day.
2. Have Diffsonline build you a diff with new seals, gaskets and bearings.

I just looked and the retail on their rebuilds is $1500 plus the LSD of your choice. Last I looked the bearings and seal were not exactly cheap and considering time, effort and the chance of getting it wrong I don't think that is a terrible option.

I've installed a few LSD's and not one has need to change shims to adjust the ring gear pattern, they've all been just remove and install so very simple in that regards.

Another option would be to reach out to David Green at Synro Design Works, he builds diffs. I haven't used him for no other reason that I just haven't but wouldn't shy away from it either.

Lastly, re: M3 diff keep in mind the diffs wear out and according to Dan @Diffsonline anything over 100k miles should be considered "tired."

[cakM3]

I did the LSD install on my last ZHP and purchased my LSD from Rob who purchased it from the Turner web site. Mine was a 3.46 LSD. I went down to New Jersey and Rob helped me install my LSD. The unit I got came as a complete unit so it was a simple swap in my case and Rob made the install look so easy.

[zhaireszhp]

Yeah, I haven't seen/heard of anyone actually having to replace the shims upon installing the lsd into old carrier. I saw seals online, they're not super expensive so that's not too big of deal to me. The bearings or races however I have yet to find, at least ones I can be sure are OE spec. The only tool I'd need to get for the job would be some type of gauge to measure backlash.


Yeah I've seen that the M diffs can use refreshes due to clutch wear, I have seen kits online for them. BUT from what I can tell from all the install videos/install guides the process seems much more involved than swapping an open diff for an LSD. Only reason I'd prioritize getting the M3 rear end is so I could tell myself I'm like a third of the way into the S54 swap I think about too often hahaha.