adjustable fg diff, only one grub screw how do i work it? help please

[new-fg-owner]

hey guys i bought a second hand alloy adjustable diff everyone on here keeps saying about how the diffs have two grub screws opposite each other on the diff housing, however mine only has one! when i tighten it untill it doesn't go anymore it is a lot harder to turn tighter n visa versa when i undo it. i notice when its done as tight as it can both wheels turn same but when its lose one doesn't thats normal i guess?
ya just some advice on what i'm doing would be great and why it only has one grub screw does this mean its a particular type of diff thanks guys.

 

[renbar]

try posting up a pic that will help us as to what diff youve got

 

[new-fg-owner]

hey renbar my files are you big i dunno how to make them smaller its saying there 3.5mb ive used my nikon dslr

 

[new-fg-owner]

hey i just uploaded the photos hopefully they are showing otherwise i haven't a cluse where they have gone ah

 

[jdfoxracing69]

lol looks like mine an yea mine dose the same thing yours dose the tighter it is the less slip the wheels are alawed soo all the way its locked all out it lets it slip i run it almost tight i find you can run full throtel around corners an no prob but when i run it tight it wants to role over or slide all over the place

 

[new-fg-owner]

hey jd thanks for your reply so when you have the car off the floor on like a stand when you turn one of the rear wheels what happens to the one thats left alone? on mine the wheel that i am not turning does turn the same as the one im turning, sometimes though it'll stop or go backwards for a moment, this is when the grub screw is as tight in the diff as possible, the loser i go the less the left alone wheel spins the same as one im turning. is this normal and what happens with yours?

 

[jdfoxracing69]

hey jd thanks for your reply so when you have the car off the floor on like a stand when you turn one of the rear wheels what happens to the one thats left alone? on mine the wheel that i am not turning does turn the same as the one im turning, sometimes though it'll stop or go backwards for a moment, this is when the grub screw is as tight in the diff as possible, the loser i go the less the left alone wheel spins the same as one im turning. is this normal and what happens with yours?

hey yea when mine is on the stand and for say.. i turn the right rear wheel clook wise the lefed rear wheel turns the same way when the grub screw is all the way in (tight) when the grub screw is loos an i turn the right rear wheel clook wise the lefed rear wheel turns counter clook wise thus makeing the diff slip ... so if u turn the drive shaft hold one of the rear wheels the other one will turn as the one you are holding wont grug screw in (tight) turn the drive shaft an you shodnt be able to hold the wheel they shod both turn in the same way an at the same speed withs is ok for stright track mudding that kinda thing but if your raceing a track with tight corners an so on its not the best * i find but every one is diffrent * i find it slides an spins out more if u have the grub screw in thight hope this helps oh BTW mudding is bad for you car if its not water proofed an a really good air filter i do but that just with a baser i don't really care about but just a heads up u can reck your car lol

 

[new-fg-owner]

heey dude thanks for your detailed reply really good of you ok so sounds like my diff is acting how a adjustable diff should be, so you said when you hold one wheel still you shouldnt be able to turn the other wheel? also the grub screw on mine as you can see in the pic is at a slight angle is that normal? i just use my car in a carpark usually don't use it in the wet yet would like to but worried it would damage it.

 

[jdfoxracing69]

yea water an sevos/gas engin isnt the best lol an did u bye you fg used cause when i was looking at the pic i noticed that , at one time it may have been cross threaded but yes in theory when you hold one wheel still you shouldnt be able to turn the other wheel but u shod remeber ther 1/5th so your hands will put out more torque then the motor ever could an its about the gear oil you have in it as well ther diffrent typs thicker less slip thinner more slip as well

 

[new-fg-owner]

yaa i bought the car second hand, the diff i only got the other week got it off ebay. will the fact it looks cross threaded affect how tight i can do up the diff? i hope not because the guy sold it saying it was fully fuctional and works exactly as intended.

 

[new-fg-owner]

hey mate ya i just took out the grub screw and put it back in, if i do it up very very tight it makes it very hard to turn the other wheel while holding the other, really have to turn it hard. could having the diff very tight damage it, is it ok to run it tight or is that unadvisable? but ya i realised untill now i had it not very tight at all. it gets really hard to do the grub screw up the tighter it gets.

 

[tizdaz]

an LSD will lock the diff at max upto 90% with the grub all way in, you wont get 100% lock dude

when you say cross threaded, you mean the grub screw its self or the actual thread it goes in to?

if its the grub screw, replace it, if the thread then tap it a size up & get the same size grub for the new thread size

 

[atom3624]

an LSD will lock the diff at max upto 90% with the grub all way in, you wont get 100% lock dude

when you say cross threaded, you mean the grub screw its self or the actual thread it goes in to?

if its the grub screw, replace it, if the thread then tap it a size up & get the same size grub for the new thread size

Top Tip from Daz there.
I don't know this LSD, but admit I don't like the look of the angled grub.

Let us know how you get on.

Al.

 

[jdfoxracing69]

i don't think its the grub mind u im going off of pics but the grub screw would be a hardend steal an the diff would be a light wight aluminum ? an if u do tap it make sher to take it all apart an clean it veary veary well cause you don't want any metel shaveings in ther it will wear the gears an bearings out faster then u can say oh $hit lol

 

[jpblue1000]

The adjustable 1/5 scale diff if like its real brother in 1:1 land is designed to differentiate between the inside and outside wheel when turning a corner...ie the inside wheel travels less distance than the outside and thr diff allows this. however in allowing this trait the standard open diff will have a tendancy to transfer power to the wheel with the least grip, generally causing the wheel to spin faster yet the wheel with grip gets limited to no torque and transfers less power to forward momentum. the locked diff or standard diff with partial locking devices...not an lsd... is designed to limit the trait of single wheel spinning under power by locking either side together by a percentage detremined by the friction applied by the device grun scres clamping force, spring preload etc. as soon as the power applied overcomes that co-efficient of friction it will again be an open singe spinning diff. it could be a 10 percent extra effort required all the way to 100 percent fully locked solid axle or spool diff. this means as you tighten the screw more the effort to stop one wheel when the other is rotated grows and the coefficient increases to the point there is no differential movement. Once locked or largely locked the diff now portrays another charecteristic of transferring equal or close to equal power to both wheels which is better for forward progression however of axial transition ( turning) is compromised as pus or understeer can becoem more prevalant. In th real world a locked diff makes the rear wheels skip when turning as the tyre now is here differential movement occurs. However in a LSD you get the best of both worlds, under throttle off cornering the lsd is open allowing smooth turn in and the transition to locked or partial lock is applied durning accelleration minimising wheel spin at the wheel with limited grip. as soon as grip is limityed and 'sensed' by the diffs mechanics, ramps and pre-loads it begins its locking effectively allowing both wheels to transfer power. this results in better accelleration and braking stability, less understeer and a faster lap.
your description of the diff sounds right, the grub screw does not look right unless it is placing a friction load against the sun gear at an angle.
Justin

 

[new-fg-owner]

hey justin tizdaz and atom thanks for your replys, and thanks again to well all of you and justin for that great detailed explination of the diff really great. i was thinking about tapping but everytime i have tried something like they i have ruined parts gettin on for like £100 of bits of done wrong haha ah.
i took the grub screw totally out and the tread looked ok nice and clean and the diff from all your really great discriptions seems to be doign exactly what it is meant to. bit confusing i think i might run the car see how it handles what happens n then go from there.
but ya its odd that it only has one grub screw, i cant find any anywhere that only have one. is there any danger of the grub screw being in at an angle chance o over loading or wearing of the gears inside the diff? when i took the grub screw out it looked like it was designed like it hmm :s because ya the thread is lovely and clean not as if it had a grub screw forced in. thanks again guys amazing of you all

 

[new-fg-owner]

hay guys took my car out for a spin today was awesom haha had the diff tightened as far as i could and ya as soon as i put the power down the thing just span like crazy, did have cold tires to but woah can see the difference, losened it up a few turns still had some spin but not to bad. then i lost a grub screw on the spur gear doh end of run after half hour.

 

[tizdaz]

bit of threadlock dude but don't use a strong one on grubs, just use the blue one, this way easy to get out but will hold under vibrations etc

 

[new-fg-owner]

haay tizdaz yaa i bought some more the other day was gettin so confused with the colours i stupidly used red a while ago n now thinga are seized on so ya using blue now thankfully.

 

[atom3624]

haay tizdaz yaa i bought some more the other day was gettin so confused with the colours i stupidly used red a while ago n now thinga are seized on so ya using blue now thankfully.

Read other posts, some say use heat - heat gun, whatever, and this can help loosen the tougher threadlock.
Red's not the strongest by the way ...... !!

Al.