Chassis TB-02

[Ritchie 6]

Hi Guys, i am looking for some help, i have started building the chassis for the Calsonic Impul Porsche (item no: 58329)and i have been having trouble building the differentials for the front and rear in that when you screw the two plastic parts together with the Spur gear & ball bearings, the instructions state that you have to tighten the screw a littlebi t at a time until the spur gear stops slipping. I have found that i have had to tighten the screw quite a lot in order that the spur will not turn!

My question is - is this normal as i do not want to proceed any further in case i have to strip the diffs down again because of a mistake.

Can anybody help please?

[taliesin 260]

These diffs are notoriously difficult to build and keep working. I have a TB-02 that I just hate passionately for this very reason - otherwise a lovely bit of kit.

Basically, you tighten them as tight as you dare, knowing that if you don't get it tight enough you will need to disassemble and re-torque but if you over-tighten you will certainly snap that long threaded bolt which costs a packet to replace. Good luck.

I never really found anything that worked for me, so the car sits in a box unloved and unused. And yes, I broke that miserable spam-loving bolt twice. Its easy to do. The next 18 times it was too loose and needed re-torqued.

There is one trick to simply popping the left rear drive shaft out and re-tightening the diff once the car is completely assembled, but that isn't much help to you now other than knowing it is possible and even likely, so don't despair if the diff slips a bit - you can re-torque it to some degree without total disassembling. I assume the front would be similar but haven't had much trouble with the front.

The other option which I've considered is just locking the wretched things.

Others may be able to help as I know this car was raced and pretty well regarded, but from memory I asked the same questions, got some tips but still had trouble.

[danb1974 93]

If you refer to the screw which goes though diff and adjusts it

The diff has to be assembled using the special ball diff grease, and not other grease (which will make it slip - don't ask how I know). Because you have metal balls on metal plate and you don't want slippage there but you want greasing.

Then tighten the diff bit by bit until it does not slip, with care, on the tb02 it seems that screw is weak and may break

Another thing to look for, the shaft is a tad short and will move back and forth. That will round the ends in time. If so, either back then there was a shaft from another car, a tad longer, which fit, or you can get creative and glue like pieces of rubber on the shaft ends, just enough to prevent it from moving but not pressing against diff gears.

[Ritchie 6]

Thanks for the help

[Dances With Cages 1]

I've found the best things I did for my TB02 diffs was to replace the plastic diff halves with Yeah Racing TB Evo III aluminium parts, and replace the screw with the HPI one of the same length. The HPI screw is much stronger, so they can be tightened without fear of breaking, and the alloy diff halves are bombproof.

I'd guess the TB02 was a bit of a rushed job with it's flakey standard diffs and the previously mentioned short shaft, but a few well chosen upgrades improve reliability hugely. Adding an alloy motor mount, universals, and shimming the diffs correctly in the housing is the icing on the cake.

[qatmix 794]

The Diffs on a TB02 are fine. I ran one for a while alongside the evo3 as a wet car and it never had issues.

Ball Diffs are a bit of a dark art so I can see how they seem intimidating. You always need to rebuild them at regular intervals as they are not as simple as gear Diffs.

Just do the following:

Just use tamiya ball diff grease on the balls and a little on the plates.

Use some tamiya aw grease on the thrust bearing.

Squeeze the spring a couple of times before you fit it in the diff.

Check the bolt is seated properly in the diff halve

Screw the bolt through until the diff is connected together.

Twist the two halves until the main diff bevel is not easy to move

Pop it in and then do not over tighten the top bulkhead cover. This is the main issue as if it's over tightened (I.e by people who use electric drivers) it can warp the bulkheads and they rub the Diffs and that makes the Diffs come loose etc. also ensure you use the right screws as longer screws also warp the top and can rub the Diffs.

Drive it for a few laps and test the stiffness, if it feels like a basic tamiya diff the it's way too loose. Just pop out the shaft and slide in your next driver and do a 1/2 or less turn and try it again for a few laps, do this until it feels fine.

As an aside, The bolt used in the tb02 diff is totally fine. It is used in most if not all of the Diffs and I've never broken one.

[WillyChang 1814]

The TB02's injection moulded outdrives can be hit & miss... sometimes not every sprue is moulded true, if/when they warp your ball diff will be notchy. When we ran them we would buy several spruces of outdrives to find ones that turned truest.

EvoIII's outdrives were not injection moulded but machined from billet nylon. They turned true both white & black versions. Probably hard to find many spares for today.

The M2 bolt often breaks when you've bottomed out the spring - shouldn't tighten that far. There's various different screws for TRFs, Yokomo etc that will fit, but most are already hi-tensile steels... this is a strong & BRITTLE metal. We easily broke more outdrives rather than screws... a couple of ready built diffs always in spares box when we actively campaigned this series - could pop out the diffs & swap in under a minute.

3rd party alloy diff outdrives should work ok (just watch for wear on alu dogbone ends of there's no nylon cushion); diff outdrives for EvoIII, Evo4 & Evo5/TB03 could also be made to work.

The real dark art was knowing how to shim the EvoIII bevel gears so they didn't jam or skip. There was also a difference in centre shaft lengths, was an unannounced running change... but the TB02 "should" have gotten the correct silver shaft in the kit.

[Ritchie 6]

Thanks for the advice guys