BJ4WE Slipper
 

Hi guys, I need your help.
I raced my BJ4WE this weekend and twice during the meeting the slipper clutch came loose.
I have never experienced that problem before but this weekend the entire slipper was brand new so I figure I must have built it wrong somehow.

After it had loosened the first time, I took it apart, replaced the screw, steel nut and spring with new ones and also flipped the pads so that the unused side would be "slipping" to make sure I would not have problems with the glassy surface of the side that had slipped excessively.

I then loctited, the inside of the steel nut with a needle and put everything together.

On the last A-final it came loose again...

Can someone please share with me, and maybe others, details on how to build and set up the BJ4WE slipper clutch correctly so that we don't need to feel worried about it coming loose?

And if I need to loosen the slipper to have more "slip" during a meeting, how do I then make sure it does not come loose after the adjustment?

I would also like to take the opportunity to say a big THANK YOU to all you guys on the forum contributing to help out, you are all fabulous!!


Regards,
Roy

Did you rebuild the slipper during a race meeting? it's pretty hard to make it fully reliable through a race meeting i'm afraid to say. The one way i've found to make the slipper reliable after it has loosened off in a race meeting is to use glue on the T nut, and leave pleanty of time for it to cure.

The slipper has been a pain for me whilst running the car, there seems to be quite abit of a difference between batches of the slipper hardware (screw,t nut, springs etc) as ive built my own, and also Jimmys slipper exactly the same yet they are completely different (his works, mine backs off!).

The only definate way of a backup for a mid meeting crisis is to have another full slipper assembly ready, however I don't wish to do this my self, either.

i've recently tried to install a thrust bearing on to the screw to make the slipper adjustable and not back off (thanks to mr price for the idea) mid meeting, however ive not had time to test this out. I will let you know wether it works or not when i get chance to have a crack with it.

I see an article coming paul? :D

That would be very appreciated because having to be afraid of the slipper backing off was not fun at all...

I also seem to have a problem feeling when the spring is fully compressed (to know where to set it). When I rebuilt the slipper before the meeting I probably overtightened the first T-nut since the ears came off... Is there any trick to know when it is compressed or is it just me that has no "feeling" in my fingers :-)

//Roy

I had similar problems at the Tivvy national with mine. Think I used three or four slippers that day, with varying degrees of success as to how long they would last before they started to slip. Sometimes it would be a couple of laps other times it would happen towards the end of the race.

Like Paul has said I think it must be something to do with the manufactuing tolerances. The one I have in S4 at the moment has performed faultlessly, but was built by the same person and in the same way as the many i had problems with at Tiverton :confused:

you can read me like a book jimmy haha!

I can't 'feel' the tension either when screwing it down.. I think this is some type of american witchcraft!!

I normally adjust it bit by bit, get two wrenches in the outdrives and feel how much it is slipping by hand. Alot of it is trial and error untill you get a good feel for it.

Then without overadjusting i'll then test it out in the car by doing either of the two methods as shown above in this thread.

Also, are you using the new 'steel t nut' option part? this seems to be better.. but with the lack of nylon you can't readjust it mid meeting

Stay tuned for a full on article, jimmy blew my cover haha!

Use the metal T-nut, and when you build it as per the manual compress the spring once with a pair of pliers, put a small amount of threadlock on the screw and tighten it 100% then back it off 3/4 of a turn and leave to set over night, buy a spare one also

Lee, I use the metal T-nut. I also compressed the spring using pliers. I am not sure however that I got the spring fully compressed since I can still turn the screw when the metal ears on the T-nut touches the bottom of the outdrive. That was what happened on my first T-nut, I snapped the ears right off it when I tightened the screw...
...And I guess it should be extremely hard to turn the screw with the spring fully compressed which in turns means that the spring was not fully compressed even when the metal ears on the T-nut was making contact with the bottom of the outdrive?

Yeah the T nut will touch the botom of the out drive but keep going until the spring is compressed, you will feel it but go easy, then just back it off 3/4 turn.

Also on the nut you snapped the ears off, was it a plastic one or metal?

It was the metal one! And ofcourse it will snap every time if I screw it passed the moment when the metal ears touches the bottom of the outdrives.
Could it be an idea to use a thrust washer also on the nut side of the assembly? That way it would not need to screw in so much before compressing the spring fully? Or does that have other "not wanted" side effects?

I'd personally try to get the slipper working properly the way the manual says.. i'm experimenting with the thrust bearing to see if there is an improovement.

The washer could work, but do it on the side with the spring and nut.
I've emailed Jason to see if they have experienced any of this on there side of the pond and if he can help with the problems.

I will take it apart and reassemble it tonight. I will try the washer on the spring/nut side between the nut and the spring.

When I take it apart tonight I will not have new slipper pads to use, should I sand the pads with 600 grit sand paper to remove the glassy surface on the pads? And maybe also on the slipper plate? And do you guys use something to clean the parts with after sanding?

Thanks for all help so far, it will be good to hear what Jason has to say about it.

//Roy

You snapped the ears off the metal t-nut? I think you need to lower the torque setting on your hand :o

The way I do it is to thread lock it (with the AE factory team blue stuff) and tighten it until the ears touch the end of the slot or I feel the spring has compressed, then back it off 1 turn.
Next I put it in the car but dont put the front centre driveshaft in so I can get to the end of the screw in the slipper. Then hold the spur and one rear wheel still and turn the other rear wheel, I adjust the slipper so when doing this the slipper slips before the diff does. Then make sure you give it 24 hours for the threadlock to set.

Apart from superglue there isn't really a way to build one on raceday, it's best to have a spare built up and ready to go ;)

The T nut should not go past the end of the out drive slots as far as i know, it sounds like you may be missing something somewhere.
It takes a lot to snap a metal nut, it also means the spring was fully compressed before the T bit fell off.;)

Yeah maybe I do, but I did not feel much resistance :D
After you have backed it off 1 turn and put it in the car, can you say about how much more you need to back it off to make the slipper slip before the diff?

//Roy

I will check and doublecheck this tonight during the rebuild, but as I said I did feel any big resistance when I tightened the screw...
I have a second unit also and I will make sure they both are built so that I have a spare one to put in if it happens again.

How about the cleaning/refurbishing of the slipper parts guys, any feedback on that?

//Roy

I took the slipper apart yesterday evening and I did not find any parts missing or wrong. I even had the manual open so that I could compare...
Cleaned the parts and put everything together again with plenty of blue Loctite... And now it sits on the table curing.
I did the same to my other slipper unit so now I will have two ready for the next race.

I also did the test of mounting it in the car without the front center driveshaft. Before mounting I backed off 1 turn. But If I am to set it so that when turning one of the rear wheels the slipper slips before the diff when turning the wheel I will have to back it off another 1,5 turns approximately (total of 2,5 turns from the bottom). That feels like a lot when the manual says 1,25 turns for more slippage... and 0,75 turns for less slippage.
The diffs are set according to the manual also I should mention.

Any input on this guys?


Regards,
Roy

Thats OK, all the parts differ slightly; the setting in the manual is something to get you started. When I've built the slippers sometimes it's been one turn to get it to slip, somethimes two.

It doesn't matter how many turns out you are, so long as the slipper slips before the diff and the screw is threadlocked it's fine :)

Thanks Richard, your feedback is very appreciated.

Regards,
Roy

I had the chance to test the car again after the rebuild of the slipper and you know what... It came loose again after about 1,5 battery packs!! *frustrating*

i have also been wondering exactly what it is that makes the screw come loose. It is strange since everything except the pads and the spur is hexed together and can not spin individually. What I have come up with is that it has to be:
0. The metal or plastic T-nut will never move since it is "locked in" to the outdrive with the T-ears
1. Heat makes the threadlocking compound weak
2. Vibrations makes the screw unscrew itself from the t-nut
3. Loose slipper = Game over!

I have a few ideas that I would like to share and hopefully get your opinion on.
I think that it might be my Loctite that is not working the way it should (it is a "normal" strength threadlocker from Horizon Hobby) so now I have ordered the original Loctite 2701 (new formula for Loctite 270). That is the strong stuff. I also got a tip to put a drop of thin CA on the T-nut after setting it up.

But I have another idea also:
Would it be possible to set it up using a regular lock nut? If I could use a regular lock nut it should be possible to also fit in a thrust bearing that in my opinion should make the nut spin with the screw instead of the screw unscrewing (since the t-nut is locked in place by the T-ears). What do you think about that guys? I can certainly test it and feedback to the forum if you think it is worth it. If someone could tell me what size nut I would need for the diffbolt screw it would be very appreciated.

Regards,
Roy