8ight / t 2.0 gearboxes

[mottman]

Hi everybody,Mottman here. Hope everyone had a good Thanksgiving ! ( don't wanna even think about turkey for at least 6 weeks ! ) I know I don't post often But, with the weather outside all bitter cold n nasty , and the 8T-1.0 all apart for heavy maintance and yeah I got some questions . I figured I would play seek n peck at the keyboard for a bit and pick you'r brains a little .
Anyway, here's the deal; While ripping down the truck I noticed that both front and rear diffs are now a very loose/wobbly fit in the gearboxes. I thought " how could I have beat out the diff bearings this bad in only 8 or 9 runs sinse the last teardown ?:eek: Knocking the gearboxes apart I actually found that the bearings are ok ( not like new but not really that bad ) the problem is actually the gearbox housings themselves ! :mad: I know I read somebody's post on here about the gearboxes stretching a little ,but this is way more than what I was thinking . The gearboxes have stretched so bad arround the aluminum bearing inserts on the rear, and arround the bearings themselves on the front ,that both whole diffs can be wobbled arround in all directions an alarming amount with shocking ease ! amazingly, all the teeth on both rings and pinnions look fine .( I really cant imagine how ) It's pretty obvious I gotta replace both gearboxes asap before the gears fail but I wanted to know if LOSI has made any improvements to them lately ,specifically to the material . It seems that the gearboxes are too soft and flexible ! Anyone else notice this problem ? Are the new 2.0 gearboxes any stiffer ? Does LOSI offer maybe a lipo/ extreme power upgrade kit with rigid composite gearboxes ? Anyone have any suggestions ? The truck only has 3 days on the track (35 runs ) ! Anybody have any good ideas let me know . Thanks. Mottman . And happy hollidays !:(

[jshbetz11]

I'll try my best!!!(rolling up sleeves) i dont own the truggy but wear n tear is universal so on that.... is the diff shimmed? how bout bearing wear?(oersonally I think this is your problem) Seems like your bearings locked up and spun withi n the diff housing, therefore allowing the slop in the housing. I'm buzzed so sorry but I believe u mentioned no damage to the center diff? That leads me to think the driveshafts(not proper name) are bent allowing for the weight of them to be put out of round when spinning? I poersonally think for the front n rear diffs housing to be worn out u got bent driveshafts or bearing fail. The odds of both set of berings is slim so hmmmm. Do u run on sandy tracks?

[jshbetz11]

I'll try my best!!!(rolling up sleeves) i dont own the truggy but wear n tear is universal so on that.... is the diff shimmed? how bout bearing wear?(oersonally I think this is your problem) Seems like your bearings locked up and spun withi n the diff housing, therefore allowing the slop in the housing. I'm buzzed so sorry but I believe u mentioned no damage to the center diff? That leads me to think the driveshafts(not proper name) are bent allowing for the weight of them to be put out of round when spinning? I poersonally think for the front n rear diffs housing to be worn out u got bent driveshafts or bearing fail. The odds of both set of berings is slim so hmmmm. Do u run on sandy tracks?

I run the 8.2 buggy race roller n havnnt had no problm except for mu own driving fault

[jshbetz11]

ooh ya, Happy Holidays back at yu

[mottman]

Thanks for the reply. It is kinda wierd. When I first got the truck , right away I installed the aluminum inserts . I wasn't too pleased with the fit ( they were too wide and seemed to be sideloading the rear diff bearings) or the fact that the left side insert had no means to keep itself from spinning in the gearbox . I drilled n taped a 4/40 x1/4'' setscrew into the side of the left insert to work as a lock pin and cut a small knock in the gearbox for the pin to fit into( definatly has not spun at all ) Then I plained about 0.007'' off the inside face of the left insert to relieve the bearing sideloading, and shift the diff over to the left a little bit ( 0.003''), and finally shimmed the ring n pinnion ( 1-8x11x0.002 shim on the right side of the diff, and 2-5 x7.5x0.002 shims behind the pinnion ). When I finished this setup the gearbox felt tereffic . BUT each time I knocked down the truck after a day of raceing I noticed the mesh loosening up more and more , requireing more n more reshimming .I also niticed that the mesh seemed to be easier affected by how tight I socked down the 4 gearbox bolts.( kinda proving the gearboxs are stretching ) Now both gearboxes are too loose to hold onto the bearings ( front ) or inserts (rear ) firmly . The bearings themselves seem ok and even trying new bearings and hand fitting everything together THE DIFFS STILL FIT TOO SLOPPY, it is definatly the gearboxes. The big question is ;how are we supposed to keep the gear mesh correct under load (every time u hit the gas with a little traction ) if the gearboxes keep stretching this easily ? And with the violent acceleration of high power brushless setups or the extreme torque of serious raceing 21,s and 28,s ring n pinnion failures gotta be almost impossible to avoid .Anyone else agree we might want to ask LOSI to at least offer gearboxes made from a stiffer material ? Let me know what you think . thanks . Mottman.

[AutieBender]

Losi makes aluminum gearbox inserts. The problem is the plastic inserts wear out. For your front end:confused::eek: But I have about 6 months on one of my buggies. I race 8 times a month. That car has a LOT of track time but still has the original gearboxes. Also has original ring and pinion.