redron123

iTrader: (87)

I went to buy a front ball diff from hpi for my sprint2 sport and they were out of stock. I saw they had all the part to rebuild one so i called hpi and they said yes all of its there if you buy these three bags of parts. I got all the parts and tried looking at the instructions online and it seems they dont match up. I am pretty mechanical and i have tried putting it together several different ways. It just does not seem to perform they way it should. In the online instructions it shows a nut that is not there. On my diff one side is threaded inside. i suppose that is to do away with the nut but without updated instructions i dont know. If someone could get me instructions or draw me a picture at least explain what parts things go on what side like short and long and also in what order i would be most thankful.

redron123

iTrader: (87)

anyone?

mattleegee

iTrader: (9)

are you replacing a ball diff? (as in can you take your old apart and learn from that?)

wish i could help, you should post pics of what you got

tc3team

I used to have the HPI Pro 2, and that did not have any thread in the diff, and I would imagine the Sprint and the Pro share similar transmission layouts.

usually, you put the diff bolt through the thrust race, then the other end is held in by a a nut and I think a plastic sleeve which then stops the diff nut from turning inside the diff, or the diff outdrive had a recess in it which stopped the nut from turning - but I can't remember exactly, as I had the car in the 90's and then sold it.

Hopefully that is some help to you.

redron123

iTrader: (87)

It is an hpi upgrade part for the sprint 2 sport. It is not the stock diff and i dont have the one im replacing to look at because its no the same. I am refering to the assembly of the diff itself. I am building it out of all the replacement parts because they were out of stock of the complete diffs.

redron123

iTrader: (87)

Yes exactly what the exploded view looks like online but this diff does not do that. I have been in contact with hpi and they are trying to get me a schematic.

tc3team

I forgot to mention the preload spring, but im sure you're aware of that too.

I think from memory 1) get your diff bolt, 2) then put the thrust race onto it, then slide through the diff assembly, then 4) the end nut and captive washer() hold it in place to the inside of where the driveshaft goes in - or it simply sits inside the differential outdrive to prevent it from spinning around.

The only other possability is that you have been supplied with the wrong parts...

That's all I can remember of it.

tc3team

The only other possability is that you have the wrong parts in the bags

Hopefully their assistance will clear things up.

redron123

iTrader: (87)

Right parts and no help from hpi.

Rockin Rich

iTrader: (1)

Assemble the diff as in the instructions, however the thrust screw will be held in the threaded side of the diff with no nut. Use blue locktite on the screw threads or it will loosen too quick and you will not be able to maintain diff settings, check diff frequently.

redron123

iTrader: (87)

Do the thrust washers and small balls go on long side and the spring under it? If so i have it put together this way and all it seems to do is tighten up when i turn the diff one way and loosen when i turn it the other way. I dont see how it will be tightened up enough so that the middle wont spin when ends are held per instructions but if you turn one side of diff the other side shoud spin the oposite direction with it this tight.

Rockin Rich

iTrader: (1)

I think from the inside it should be washer-spring-washer-diff balls-washer- screw head, and yes in the long side. And do not forget to use grease, like Asso. Black or some other type on the diff ball and washers.

redron123

iTrader: (87)

There is only two washers and in the original pic it shows balls in between the two thrust wasshers.I have right now from the inside on the long side spring-washer-balls-washer.

Rockin Rich

iTrader: (1)

Sounds right.

redron123

iTrader: (87)

and it looks right but when you tighten it so when the ends are held and the middle wont spin then you cant turn one side and the other spins the other direction. If you loosen it up until it does when you spin it one way it tightens and the other it loosens.Nothing really holding it.