Land Freeder

[krisby]

I started building my land freeder last Christmas, a very slow project. Anyway, I've been on the rear diff now for a few months as I am trying to work out what is going on.

I noticed that despite having screwed together the upper and lower casing for the diff, they were falling apart. It appeared as though the screws were not making it all the way through into the second case. So rather than trying to figure out where I had used the wrong screws I ordered another packet of the 3x10mm screws as per the build instructions.

I finally got round to it yesterday, only to find the new screws are exactly the same as the old ones and yep, still don't make it all the way through. My only thoughts are to get some 3x12mm and hope that extra 2mm gives it enough purchase to bind together. However, what I can't understand is how the specified screws simply do not work, has anyone else encountered this issue, particularly on a CC01?

Cheers

Kris

[Tamiyastef]

I had a Pajero and still have an Unimog 306 on a CC-01 but never had this problem.  Have you tried putting the screws in the diff half they're supposed to go in without the other half of the diff? Just to check if the holes are the right size or too big. 

Does it work putting the two diff halves together without anything in it? If so try putting a toothpick in the screw holes to see if they line up.

It should work with the screws mentioned in the manual. Could you post a picture of the 2 diff halves together? 

[Mad Ax]

I've built a few CC01s and never had problems with the rear diff or axle not going together.  First there's a few things to check:

When you say diff casing, I'm guessing you mean the black plastic axle case, the long bit that the diff and axle shafts go into.  If you don't mean this part then please correct me.  (At first I thought you meant the diff itself, but that takes 2x8mm machine screws).  Also I'm assuming you mean all 8 screws that hold the axle together have this problem - if it's just one or two of them, please update us.

Assuming I have the right part, there's a few possible causes.  Have a check of each of these.

The axle halves are not fitting together neatly

Both halves of the axle should snap fully together and be completely closed without the screws in.  (OK, it won't stay closed without the screws, but it proves there's nothing keeping the axle halves apart).  If they don't fully close, something is amiss inside the axle.  Check that all the bearings are properly seated in their recesses, the diff is installed the right way round, the axle shaft splines are fully located into the diff and the E-clips are in the correct locations.  Also check the pinion gear is properly seated with its bearings in the recesses.  If the halves still won't fit together, check both halves for any flashing, swarf or damage around the bearing seats and closing faces.  You should be able to trim any flashing away.  If they still won't fit, take pictures and post up here.

There's a moulding fault with the axle

This would be unusual, as Tamiya QC is generally very good, but it's possible there's something wrong with the part of the axle that is supposed to accept the self-tapping screw.  There are 8 screws that hold the axle together and it would be strange for them all to be wrong, but it's worth checking.  If you try to put a screw directly into these holes (without fitting the other half), does it fall right in or do you need to apply a screwdriver to get it in?  (Don't screw it all the way, remember the top half takes 1-2mm off the total length of the screw so there might not be enough depth to accommodate the entire screw, and forcing it all the way in could damage the thread or poke the screw end out of the plastic).

If there is a fault, you'll have to find a replacement part.  If it's a genuine fault with the part, your reseller can probably get you a free replacement.

You've stripped the threads

It would seem unlikely that you've stripped 8 entire threads so bad the screws fall right out, but Tamiya plastics are known for being soft and it's not uncommon for someone new to Tamiya to overdo a screw and pull the plastic out.  If there was lots of bits of black plastic when you took the screws out last time, this is likely what's happened.  You might get away with some loctite but replacing the axle would be better.  Or you could drill right through the thread recess with a 3mm drill and use longer machine screws with nuts on the end, but it seems a shame to resort to a fix on an otherwise new car.

You're not assembling the axle correctly

It might be that you've not correctly interpreted the instructions.  I've built more Tamiyas than I can count and I still slip up sometimes, I miss an obvious part or try to screw into the wrong hole.  Take pictures of what you're doing and share them here so we can see where you're trying to put the screws and if there's something obvious that you might have missed.

Good luck