RC10Talk - The Net's Largest Vintage R/C Community

Been a member of this site for a while now and found it because of my love for vintage RC10's afte being out of the RC Hobby for a long time. However after running a B4 for a while at my club i wanted a mid engine car so went for a 22 when it came out and i love it to bits!
This made my ears prick up a bit about losi, they've always been there but i've kinda skated over them so started looking to buy an old car, jrx pro se or XX. I now have 2 XX's a standard model and a CR 1 of which i want to get rebuilt and going for a few rounds at my clubs vintage series. So i've got a few questions about rebuilds. I have found some information but could do with some more help!

Is there anything that is a must do to get it race ready mods etc? as they both look pretty standard.

Are the newer shock kits backwardly compatible with the older cars as the associated ones?

The same question also goes for the diff is there one that will fit the XX?

What is the principal behind the hydradrive and how does it react differently compared to a standard slipper clutch, i will be running a 10.5 brushless in it.

Any help to point me in the right direction would be much appreciated

I have the modern xxxcr shocks on my pro se I just had to build the shocks with the correct length shock shafts. the older Losi had much longer shafts. the diff screws are pretty much the same, I use almost everyhing xx on my prose and it works good.

Caine wrote: What is the principal behind the hydradrive and how does it react differently compared to a standard slipper clutch, i will be running a 10.5 brushless in it.

The hydra drive provides a viscous coupling to the layshaft from the motor and helps to absorb torque differences between the two - a full explanation will take some effort, its a very clever piece of kit.

BUT, I would be very careful, the hydra drive was developed a long time ago, where motors were no where near at the power they are today, so you might ending up burning the thing up - it will get warm due to friction. This is the reason Losi went for a dual-pad slipper setup.

Just be sensible with motor choice, I would of thought a non-timed (ie no boost on the speedo) 10.5T would be ok, if in doubt take it easy and keep an eye on the hydra drive.

As for the diff, you can still get the diff plates/outdrives as they are used on current Losi cars. I am not sure about the diff gear though, it might be the same as the original xxx, but someone else might want to chime in here.

Hi Caine.... firstly welcome to the 'other' side - that is Losi ownership, secondly, you've made a couple of great purchases in aquiring your two DoubleXs... these truely are great buggies (my fav of all time) & I think you'll be pleasantly suprised with how well they go compared to both the B4 & 22 - they will certainly feel easier to drive than either of the modern cars.

Hop-ups wise there really isn't anything that will make a major difference performance-wise... the cars really were that good out of the box! The only two parts that might be worth trying in order to improve the reliability/strength of the car is to get hold of an ali brace that ties together the inner hingepins on the front along with a strengthening plate that sits on top of the gearbox & spreads the load of the two fixing screws that go through into the bulkhead - these are both Trinity 'Kinwald' parts (can't remember the 'TK' no off hand).... I have seen gearbox cases & front bulkheads fail & these parts can only help. Also the RPM gear cover is a much more durable item compared to the original Lexan part.

Both the original XX & CR were both very competitive on the track & indeed some people prefered the original car over the CR but the only real difference was the change from inboard to outboard toe on the rear.... I prefered the CR car simply because the two-part 'Tee' peice seemed a stronger assembly.

Many parts from your 22s predecessor... the 'XXX CR' can be used to keep the XX going... all the gearbox internals including the diff assembly fits into the XX casing, watch out for the 'BK' XXX parts though as I believe this car had a different internal ratio? Also although the basic design of the diff remains similar between the XX & XXX some parts have changed during the evolution of the XXX - I have an original XXX buggy which shares all of its diff parts with the XX but I also have a CR2 (mid motored CR XXX) which has different out-drives/thrust assembly/tension spring & securing nut. The shock cartridge design has also remained unchanged since they upgraded the notoriously leaky seals on the original JRX2 - right up to the XXX CR. The threaded bodies on the later XXX shocks only allow for more precise adjustment, personally the clamp collers are just as good - off road racing doesn't require such accuracy Other XXX parts that can be used include bearings, Spur gears, wheels, axles & driveshafts, rear hubs & early XXX (narrow VLA) rear wishbones work too on a XXCR

Its the parts from the later XXX buggies that seem to be still stocked or supplied by model shops.... I tend to order the spares for my CR2 from DMS Racing.

With regard to the Hydradrive... generally back in the day we tended to favour the friction slipper as it was simpler & less messy - also with 1700 SCRC cells & limp brushed motors we wanted as little rotating mass as possible. However with brushless power & efficiency r-mass is less of an issue & I've seen quite a few guys running the Hydradrive on their Atomic Carbon CR2s - it is reported to really soften out the ride & make the car easier to drive especially on really bumpy/rutted tracks as the unit damps the 'shock' forces through the drive-train. Those guys I saw running this unit were running 6.5s etc so I don't think there is a problem with the durability?

Thankyou ror the responses guys
Sounds like i've got something to look forward driving soon! Now i've had some time looking through the manuals etc, i have managed to get up an order for shock and diff rebuild parts and i'm now on the hunt for the braces that Derby Dan mentioned.
Both are in bits at the moment will get everything cleaned up over the next few days and start rebuilding.

I will be running indoors on a mixed surface track ( carpet and polish with plenty of jumps etc ) so i'll think i'll keep with the standard slipper for the moment then try the hydra when i'm feeling a bit surer of the car.

Any advice on setups for running indoors?

I have a newer style rear Trinity brace (with the extra supports for the bulkead too) for sale - NIP, PM me if you are interested.

You definately wont need the hydra indoors - its meant for rutted/bumpy tracks to assist in putting the power down.

Dont forget to post some pictures - we like pictures

Yup, pictures are always good!

Its funny - I've got one of those gearbox braces with the extra 'ears' for my build... but my original car had just a tiny rectangular peice, I would prefer one of these since i'm trying to re-create that car... but thats just a small detail!

Set-up wise for indoor racing.... try & get the car as low as the jumps will allow, green springs on the front, pinks or reds on the rear & 30wt shock oil with the kit red pistons - this was the basic set-up for any track to be honest. Run the tyres that all the other guys are using at your club... I presume they use Schumacher Yellow Mini Pins on the rear & either pins or stagger/cut staggers on the front? IIRC I used to run a roll bar on the rear to try & keep both wheels on the track & avoid 'diffing' out - this also helped keep the rear end a bit loose to really get the car to hook into corners... on tight fully carpeted high grip tracks I used to run the original XX hubs swapped sides on the CR rear end to give 0 deg toe - this avoided tyre scrub & helped high speed corner traction.

Racing on these tight indoor circuits was kinda my speciality, back then they were mostly flat, maybe with a few removable ramps that could be taken out for when the (then latest 'thing') touring cars raced. I did pretty well in the Silverstone/DMS indoor series..... lately on my return to buggy racing... massive ramps & obstacles seem to be the norm & its taking me a while to get used to these!

My old Losi after a BRCA indoor/winter meeting at Worksop

Thanks again
Will post some pictures when i've got at least one rebuilt, not much fun taking shots of a cardboard box full of bits!