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  1. #1
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    3.3 diff swap question

    I just received the last of the parts to do the swap and started tearing the car down. The rear is pretty straight forward but the front has me stumped. I cant figure out how to mount the front diff bearings into the housing. The stock hole is for a 5x10 bearing so the 10x15 obviously wont fit. The sticky on the swap only says that it is a direct swap and doesn't go into detail on how to make the front bearings fit. Any advice would be greatly appreciated.
    2010 HHR= Half a Hot Rod

  2. #2
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    You don't change the bearings just the diff. Like the sticky said it's a direct swap.

  3. #3
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    The problem that I run into is that the diff housing is molded for a 5x10 bearing and the diff only accepts a 10x15 bearing, so there is no way to physically fit the bearing into the housing. Do I need to cut the housing with a dremel or machine down the diff to accept the smaller bearing? is it possible that there was a running change along the way and later electric 4tecs used a larger front diff bearing? I assume that this is not the case as I have only seen one part number for the front diff housing.
    2010 HHR= Half a Hot Rod

  4. #4
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    Are you sure there arent 2 removable spacers in the front that held the stock bearings? Those go and the larger bearings should go in. Sorry been years since i've done the swap.

  5. #5
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    I just checked the diff housing again and there is no insert like the rear. It is molded to accept the 5x10 bearing. If I trim the diff surface where the bearing contacts, can enough be taken off to achieve the 5mm diameter that I need? If not what can I do to get a bearing in there? The diff fits without the bearing, just resting on the housing but there is a lot of friction and the two parts will quickly develop slop and be ruined.
    2010 HHR= Half a Hot Rod

  6. #6
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    On mine there were to "U" shaped spacers that held the old bearings. I removed those and the larger bearings were a direct fit. If thats not the case then that means traxxas made a change along the way.

  7. #7
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    I called traxxas and confirmed that there was a running change in the front diff case for the 4tec. The first run had the one piece cases like mine and the later cars had the inserts. I ordered the correct diff cases, part 4318, and once they are in I will finish the conversion. I noticed that when I completed the rear the belt was extremely tight even with the cam tensioners set at their loosest settings. What can be done to loosen the belt to a usable point?
    2010 HHR= Half a Hot Rod

  8. #8
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    Some people have tried boiling it, I tried dremelling out the rear but that just got the belt to touch the motor, and for a while I joined in on the search to find a belt that had the same pitch but had one extra tooth without much success. Most of us just buy extra belts and deal with it.

  9. #9
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    Looks like I will be investing in extra rear belts then. I read in another post that someone machined down the extension on the rear diff to fit a 5x10 bearing and that solved the issue as the stock cam tensioners could be re used, but I don't know about the durability of doing this. It appears that there is very little extra material in that area on the diff and I would be worried about causing slop or possible causing the diff to leak, I hope the belts last a while, everywhere I have tried so far wants $10 or so per belt and if that is a frequently consumable item, I may have to reconsider the project.
    2010 HHR= Half a Hot Rod

  10. #10
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    I got the new front diff housings installed and both belts on. The friction is a lot worse than I expected. I also used new bearings throughout the car so I know its not a seized bearing. I really hope this thing frees up once it is ran for a while. I am also having trouble with the rear stub axles. I cannot get the axle to come through the carrier far enough to install the cross pin. I am using rustler rear hubs with the 5x11 bearings since my stock 4tec hubs were grenade on another project long ago. What can I do to the nitro 4tec axles that I have to make them fit though the carriers a little farther? I even tried using some old electric 4tec axles that had the ears broken off as a mock up and they don't come out any farther than the nitro 4tec 3.3 axles that I am going to be using.
    2010 HHR= Half a Hot Rod

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