Transmission tips?

[DrumAnBass]

My original 6 gear transmission (mid-motor mounted on a graphite chassis - bought it this way) is making some nasty grinding noises (since I bought it as well). I am guessing it might be a differential problem as it goes straight ok but the noise happens when one wheel is spinning more than the other. I am planning on taking the transmission apart, cleaning & re-lubing it and putting it back together to see if it might fix the problem. The transmissions on eBay have been selling for a bit more money then I want to invest in this car.

Haven't found too much into or tips on transmission repair. Are there any parts that I should definitely replace while I have it apart?

Any suggestions for what differential grease to use? Is there a readily available silicon grease that I can use on it? I am guessing modern Associated transmissions might use a grease with less viscosity...?

Any tips & tricks would be most appreciated! Thanks!

[jwscab]

there is probably a bunch of dirt and gunk in the diff, since it's open to the elements, more than the internal gears.

I would take it apart, and wash down everything with a good cleaner, soap and water is fine, or something like simple green. be careful with simple green and aluminum, you can use it to clean, but wash it off immediately, don't soak it.

carefully check the bearings/bushings, and clean them out as well as possible, I usually soak bearings in mineral oil, spin them a bunch, and then resoak, then wick out the oil with paper towels. keep doing that until the oil that wicks out is clean, and the bearing spins without that gritty feeling.

check the diff rings for scoring or heavy marks. you can wet sand them down on a flat surface, like glass, with some 800-1000grit sandpaper to get rid of all the blemishes, and put a nice honed finish on them. check the diff balls carefully, these are one point where it's a very good idea to replace them when you can. you should also replace the diff rings if you can't polish them up well enough.

check all the gears and the make sure they have all their teeth and don't look excessively worn. for the 6 gear, check the teflon bushings in the diff tube, and make sure they aren't worn too badly, and check the thrust bearing to make sure the balls and washers are not gouged, worn excessively, or the ball cage isn't melted.

assembly the gears dry, some thick grease on the thrust bearing, and any standard ball diff lube you can find on the diff balls.

as far as rebuilds go, thats the best way to do it. if the trans was a bushing trans, I would consider updating to ball bearings, check avidrc for $1.00 bearings, and add the 3x8" by 5x8" outdrive bearings as well.

this is just a small quick guide. there is is plenty to read up on in these forums, check the scans archives, and just search 6 gear in general. there is an article from jim halsey to improve the trans further that a standard rebuild.

[DrumAnBass]

Awesome, thanks for the great suggestions! Yah I did buy a set of bearings from avidrc; I believe it already has bearings but i figured it would be good to swap them out.

I also ordered some white lithium grease and some MIP differential lube. Anyone have a part number for the diff balls, or a compatible 3rd party set?

I'll post some pix when I get the chance to tear the thing apart.

[jwscab]

check out www.rc10.com, in the resources and downloads, you can pull down the entire manual for many cars and trucks they have. the part numbers will be in there, you can search on those numbers and find what you need.

the thrust washer has captive balls, and I don't recall what size they are. the diff balls are a standard size, so you just need to check around for anyone who sells the right size.

[FordPSD]

I don't know what captive balls are but can they be changed?

[FordPSD]

I got a measurement of .094 inches or 2.39 mm with my caliper on those thrust washer balls. I don't own a micrometer which I would have prefered to measure with.

[FordPSD]

Boca Bearing has 3/32" ceramic balls which are probably it. They're $3.45 each. Wonder if you can get ceramic washers somewhere? If those thrust balls can be replaced I plan on doing it!!

[FordPSD]

Heck, do a search for 3/32 ceramic balls and a lot of places pop up. Cheaper too.

[DrumAnBass]

I see this Jammin' Jay diff rebuild kit on eBay; but $20 shipped seems a little steep for a couple of washers... I figure I might be able to buy an entire transmision for a few $$ more... Thoughts?

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=360224640219

[jwscab]

if the thrust balls are 3/32", then you can probably pop them out of the carrier and replace them. captive means that balls are held 'captive' by the carrier(the blue thing), otherwise they can spin outward and fly out. You need to reuse that carrier in this differential. some diff's don't require it.

I believe the diff balls might be 1/8", so both sizes are readily available.

that jammin kit is a bit pricey. I'd check around, someone may be able to help out with diff washers. they are hardened, and not run of the mill, you can't use just anything in there. I'll take a look and see if someone sells something that can replace them. They are usually OK though, you can polish them the same as the diff rings.

[FordPSD]

I"ve seen the price of used 6 gear tranny's go for between $20 and $60 on Ebay.

For what it appears that you get from Jammin Jay I would't waste the money even though I've been spending like crazy for parts!

Once I get the rest of the new bearings in and pick up some brass tubing I'll put it together and see how it is. But I would say the biggest improvements for the gear would be bearings and working on the teeth of the gears. Right now with the white idler gears I don't feel any difference when I spin the outdrives with or without the idlers in place. The mesh is perfect.

[DrumAnBass]

Just won an eBay auction for a set of Thorp 48p idler gears so I am going to wait to tackle my rebuild project until those arrive...

[transamman908]

You should have them by wed or thurs.

[scr8p]

Just won an eBay auction for a set of Thorp 48p idler gears so I am going to wait to tackle my rebuild project until those arrive...

actually, you'll be waiting until you get a pair of thorp 48p drive gears and the 2 thorp 48p diff gears.

the stock 6 gear trans is 32p. the 48p thorp idlers are useless without the other items i mentioned above.

EDIT: well........ unless your trans is already outfitted with the 48p thorp gears, that is...............

[transamman908]

Uh-oh!!! Kinda thought that after reading this thread. I sence a refund......