Problem with fastlane diff cups

[maxxdude1234]

just got my fastlane diff cups, ripped the packaging open...and....they don't work properly. The 2 slots that the spyder gear shaft is supossed to run down are too close together and the little spyder gear shaft won't fit in the cup. Looking back at the stock cups, they have a square slot, but the fastlane cups have a circualr slots - which means the spyder shaft (which has a square end) cannot fit in. I've tried filing the end of the spyder gear shaft down, but it's chrome plated - and I don't have anything hard enough to file down chrome....:W:

Wondered if anyone else has had the same problem, and how they solved it.

ps. if you need pics to understand what I'm talking about, just ask...Thanks :)

[Sylvester]

pics please, il help you out, pics will do the honor :)

[maxxdude1234]

I've managed to solve the problem now. The spider gear shaft is very very hard stainless steel - so other than a diamond or tunsgten carbide tipped tool, the only thing I found hard enough to wear it down was......concrete!!!

My problem was that the diff cups were not machined accurately, and did not allow enough clearance for the spider gear shaft to fit in the cup....and the only way I could find to file the very hard shaft to a shorter length was by holding it tightly in a pair or pliers and filing on the my concrete patio!!! how dumb does that sound. Anyway, I managed to take enough material off to fit the shaft in the cups.

If you look at the maximizer cups in the photo the 2 slots are square, but on the fastlane cups they are rounded...stopping the square ended spider shaft from getting in the cup. Hope you understand what I'm saying...

To me this looks like a major design fault with the FLM diff cups. Either that, or severe slacking from the quality control department.....and I hope this isn't true of all their products...

[RC-Monster Mike]

A dremel works also. I forgot about this little issue with these cups. I will have a chat with Jamie at FLM to get this issue addressed.

[Serum]

it's just a little reprogramming, it should be cut a little deeper then.. Can't be that big a deal..

[RC-Monster Mike]

The problem isn't the depth of the cut, really, although a deeper cut may fix it. The issue is that the back of the hole is round (cut with a milling bit), while the cross pin has a flat end(not tapered). I use a dremel to round the cross pins and it works fine.

[Serum]

I ment a wider cut in total, so the pin can fit in. without tooling it

i've chosen the wrong words.

not to bash FLM but its not the first problem they have had with their own products.

[gcurtis2121]

Hey guys, just reading about the diffs above from FLM and wondering if the problem has been fixed yet. I think I stripped a diff yesterday, gonna tear it apart today and find out. But I want to put something in that I won't have to keep replacing, and I don't want to have to grind stuff on concrete before I put it in my truck!

[maxxdude1234]

I believe Mike (the owner of rc-monster) was talking to fastlane machine about the problem. Don't know if the problem has been fixed or not.

If it hasn't yet, a dremel would do the job in a second (providing you have one - I don't so holding the spider shaft in pliers and filing in on concrete was the only answer). If you have a decent set of hand file, they should do the job. Other than that you can buy an aluminium oxide grinding tool from anywhere for about 1$, chuck that in a drill and off you go. But bear in mind you will need an extra pair of hands or a vice to do this....

[RC-Monster Mike]

Greg, I can mod the spider gear shaft for you if you would like (Obvioously you will need new spiders as well as the diff cups, which I have in stock). Just remind me when you place the order. It is wuite easy to modify the shaft, as maxxdude mentioned.