Rear Differential Help Needed.

[Winger]

I have the "6 Gear" and when I hold the large gear that I have labeled "B" and twist "A" it is very rough turn. The manual says it should turn "very smooth." It clearly is not smooth. I have taken it apart 5 times and every thing is smooth until I install the spring and "tighten it down until even with the shaft." No parts are issing. I am wondering if the balls in the the gear I labeled B (ring gear?) have gotten too small with use and is now being smashed by the large washes that ride on those balls,but I have no idea....

Does anyone know what might be going on here?

[1990Racer]

Is it a grinding type? Are you using grease? Also the gears have probably changed since they were new from the factory. I have 2 TQ10s (6 gear) one that I raced a long time ago has been ran more than the other and it feels more like gears rotating more rough than the other one that was hardly ran at all. Do you remember what it was like before disassemble? The gears just might be worn out.

Not sure though hopefully someone more knowledgeable will chime in.

Sorry just read that again, have you flipped the B gear?

[jwscab]

any roughness in the diff is from usually these things:

diff rings or thrust rings are scored, easily seen as a shiny ring where the balls ride. Typically replacement is best, or if you haven't yet, you can flip the rings over or sand them flat with sandpaper on a very flat surface until the groove is gone.

diff or thrust balls that are no longer round. replacement is usually the only option.

if all those parts are new or known to be good, the only other thing is some kind of binding. check to be sure the holes in the diff gear are clean, clear and not melted. Unless you have changed the diff balls and used the wrong size, once assembled, you should be able to rock the spur gear around a little and see that it's not pinched in the diff plates.

[Winger]

I finished cleaning and reassembly, but the trans case has to be torn down again. I noticed this before the tear down and was hoping a good cleaning would do the job...and no.

I did a little more testing on it last night. I completely removed the ring gear with "54" on it...when spinning it the right-rear tire it is very smooth. The left side is anything but smooth turning with notable difficulty, clearly something will blow if it is ran like this.

One more thing....if you just roll the car forward and back it does so very smooth.

[Winger]

I decided to make a video:


http://youtu.be/gx0WFaPYj2A

[farmer]

winger i still race my 6 gear at my local club and i have had that same problem you are having, afew ways that i have solved it was one! as said before the diff rings and balls need to be new are at the best resurfaced, unloosen the slipper spring nut tell it spins smooth, not to loose just enough to turn smooth, than look at the ring contact to the balls,now spin the spur gear while holding the top shaft so the the top shaft dont spin,does the spur and the slipper spin smooth all the way around,are is there low spots where you feel some tightness than it lets go to spin smooth? if you have high spots and low spots! it could be a couple of things one some of the balls are flattend, the spur gear can have a wobble,the rings are warped. Than start to tighten the nut and keep doing the above step and lil by lil till ither the nut is level with the thread end are you get the stutter in the slipper , look to see if you diff rings are rubbing the gear! inbetween the balls instead of floating only on the balls,if you can at full nut tighten per manual setup get a small peice of paper and slide it inbetween the diff rings and the gear turn slightly and and see if the paper is binding up inbetween on the gear, also if this car hasnt been ran in years and you are rebuilding with spare part not NEW you are looking at years of race gunk and wear that when replaced with spare that have been used before you will have a different ware patern,example if you ran that spur with the same 19 pinion race after race that spur will ware to that spacific 19 pinion,than you change to a brand new are another spare 19 pinion the mesh will not be the same,ya it will work but you get the point,what i do after a REBUILD that you might try is! after the rebuild get the batt in and turn her on and loosen the slipper to where its spinning nice and smooth than grab one tire and set the other tire up so it can spin freely,give it a lil gas not full gas , and let it spin for a little than stop grab the other tire and repeat the process,than step two snug the nut just a lil grab one tire but this time let the other stay still give it a lil gas ,than repeat with the other than, third step put both wheels down and hold on to the car and give it some gas till the slipper slips,than just keep repeating those 3 step tell you are getting the slipper to slip for your racing style,what you are doing is getting everything to seat ,also what the manual is saying is a general starting setup, my driving i like my slipper tight , also make sure you get a exacto and clean out all the race build up between all the tranny gears than clean them, i use electrical contact cleaner breaks down the grease and grime, same things with the bearings ,and one more even after all the braek in and cleaning that i do to my six gear its still a lil noisey and lil gritty but on the track its smooth and fast
hope that helps
farmer

[Winger]

any roughness in the diff is from usually these things:

diff rings or thrust rings are scored, easily seen as a shiny ring where the balls ride. Typically replacement is best, or if you haven't yet, you can flip the rings over or sand them flat with sandpaper on a very flat surface until the groove is gone.

diff or thrust balls that are no longer round. replacement is usually the only option.

if all those parts are new or known to be good, the only other thing is some kind of binding. check to be sure the holes in the diff gear are clean, clear and not melted. Unless you have changed the diff balls and used the wrong size, once assembled, you should be able to rock the spur gear around a little and see that it's not pinched in the diff plates.

When you say dif rings or thrust rings I am thinking you are meaning these:



If so mine have absolutely no scoring at all. I took the balls out of the spur gear (previously referred to as ring gear):


They rolled around very smooth on the counter.

[Winger]

winger i still race my 6 gear at my local club and i have had that same problem you are having, afew ways that i have solved it was one! as said before the diff rings and balls need to be new are at the best resurfaced, unloosen the slipper spring nut tell it spins smooth, not to loose just enough to turn smooth, than look at the ring contact to the balls,now spin the spur gear while holding the top shaft so the the top shaft dont spin,does the spur and the slipper spin smooth all the way around,are is there low spots where you feel some tightness than it lets go to spin smooth? if you have high spots and low spots! it could be a couple of things one some of the balls are flattend, the spur gear can have a wobble,the rings are warped. Than start to tighten the nut and keep doing the above step and lil by lil till ither the nut is level with the thread end are you get the stutter in the slipper , look to see if you diff rings are rubbing the gear! inbetween the balls instead of floating only on the balls,if you can at full nut tighten per manual setup get a small peice of paper and slide it inbetween the diff rings and the gear turn slightly and and see if the paper is binding up inbetween on the gear, also if this car hasnt been ran in years and you are rebuilding with spare part not NEW you are looking at years of race gunk and wear that when replaced with spare that have been used before you will have a different ware patern,example if you ran that spur with the same 19 pinion race after race that spur will ware to that spacific 19 pinion,than you change to a brand new are another spare 19 pinion the mesh will not be the same,ya it will work but you get the point,what i do after a REBUILD that you might try is! after the rebuild get the batt in and turn her on and loosen the slipper to where its spinning nice and smooth than grab one tire and set the other tire up so it can spin freely,give it a lil gas not full gas , and let it spin for a little than stop grab the other tire and repeat the process,than step two snug the nut just a lil grab one tire but this time let the other stay still give it a lil gas ,than repeat with the other than, third step put both wheels down and hold on to the car and give it some gas till the slipper slips,than just keep repeating those 3 step tell you are getting the slipper to slip for your racing style,what you are doing is getting everything to seat ,also what the manual is saying is a general starting setup, my driving i like my slipper tight , also make sure you get a exacto and clean out all the race build up between all the tranny gears than clean them, i use electrical contact cleaner breaks down the grease and grime, same things with the bearings ,and one more even after all the braek in and cleaning that i do to my six gear its still a lil noisey and lil gritty but on the track its smooth and fast
hope that helps
farmer

Thanks for such a thorough response. I will give this a go in very near future. I looked for new "differential driver rings" #6625, but no luck....thinking maybe I wil bey them and the balls just for good measure.

[jwscab]

there are also thrust rings and balls in the assembly, in that pictures,the blue disc and two washers; they all need to be as smooth or smoother than the diff rings and balls are. Often the thrust assembly is where the notchiness comes from since spring pressure is much greater on the smaller parts and doesn't often get changed.

same principles apply, new balls and sanded or new thrust washers.

the other thing I notice from your video is that you are spinning the wheels with the suspension at full droop, and not sure if you have enough limiters in your rear shocks. You could be feeling some binding in the axle/dogbone/arm interference at that extreme angle. try compressing the suspension a little and see if the feel changes. if that's the case, make sure you have a good piece of 5/8" long fuel tube on the rear shock shaft internally.

[Winger]

I took it out for first time with the new battery pack. I did not want to run it long on the pavement for the sake of tires.. My camera person was giving me all kinds of problems...

Sorry I cant fig out how to embed: http://youtu.be/KYgA-emy_VM

Maybe I will run across some new plates and ball bearings and put them in.

[farmer]

looks good in the vid and sounds rite to
farmer

[Winger]

looks good in the vid and sounds rite to
farmer

Thanks for commenting on how it sounds...I was wondering if one could tell by the sound. It seemed to be running as expected as far as speed. Ordered a radar gun...eager to check top speed! Setup some other rear wheels and tires.

EDIT: 25mph

[1990Racer]

I haven't heard that sound personally in 20 years. It did sound good though. I'll hear it soon.

Most people use a portable gps to track the speed now days.

[Winger]

I haven't heard that sound personally in 20 years. It did sound good though. I'll hear it soon.

Most people use a portable gps to track the speed now days.

20 Years! Man I am glad to bring the music to your ears. It did seem fast to me especially considering it's age.


Have several pinions planning on swapping out too. Want to do comparison; Twister v. Trinty '85.

Is there an app for Droid phones that would log the speed so i could check it?

[1990Racer]

Is there an app for Droid phones that would log the speed so i could check it?[/quote]

Yes

http://androidforums.com/incredible-support-troubleshooting/108129-gps-mph.html