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Bulletproof differential questions...

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Old 12-30-2011, 09:09 AM
  #1
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Default Bulletproof differential questions...

Hey guys... My old savage .25 just stripped the rear differential for the 2nd time (about 13 gallons on the truck... 7-8 of those on this diff), and im thinking about going bulletproof in the rear and then doing the front when the time comes...

My question is, can i use the differential outdrives that i currently have in the bulletproof diff so that i dont have to go to larger dogbones? Also, I assume the bulletproof differentials will fit right into my stock .25 differential housings? I still may go with a standard gear set since its cheaper and this one has lasted me well, but would rather go with the bulletproof diff if possible.
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Old 12-30-2011, 10:27 AM
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Default RE: Bulletproof differential questions...

Don't question it, just do it . The fact is that the front will blow out in a matter of time, I've been running the BP diffs for a few gallons and no issues. Like you I have them in a Savage 25, though I think I may have possibly upgraded to the X diff cases when I did the swap.

I would say just bite the bullet and do both at once, remember that the gears have different tooth counts so the rear will be overdriven. Its not a huge difference but its there. Yes you can use the S25 dogbones, I'm still running my stock dogbones from 2004. Its just like any other ring and pinion gear, there are no changes to the case itself.

I remember that I did the upgrade maybe a few months after it hit the market, I payed around $70 to do the whole truck.
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Old 12-30-2011, 10:27 AM
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Default RE: Bulletproof differential questions...

you have to change them at the same time as the ratio is different. als o the bullet proof diff's use a different bearing on the crown gear side of the differential. other than that. your good to go. cheers
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Old 12-30-2011, 10:47 AM
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Default RE: Bulletproof differential questions...

Thanks guys, I knew the ratio was slightly different.

29/9= 3.22
43/13= 3.30

Pretty small difference. I dont think it would hurt anything on an offroad 4x4. Id rather do em both at once, but the front diff has about 12 gallons on it and counting... hate to replace something that aint broke

I can buy the whole unit for about $35 a piece I believe. Assembled diff, case, and shock tower. Probably should just do that, but we'll see. haha

Or I could always bulletproof the back and make it 2wd Might be a lot of fun that way
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Old 12-30-2011, 02:25 PM
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Default RE: Bulletproof differential questions...

I like a 2wd savage more, just the braking that sucks lol.
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Old 12-30-2011, 03:04 PM
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Default RE: Bulletproof differential questions...

Quote:
ORIGINAL: cummins driver

Thanks guys, I knew the ratio was slightly different.

29/9= 3.22
43/13= 3.30

Pretty small difference. I dont think it would hurt anything on an offroad 4x4. Id rather do em both at once, but the front diff has about 12 gallons on it and counting... hate to replace something that aint broke

I can buy the whole unit for about $35 a piece I believe. Assembled diff, case, and shock tower. Probably should just do that, but we'll see. haha

Or I could always bulletproof the back and make it 2wd Might be a lot of fun that way
I would do both other wise it is going to be hard on the whole drive train from the tires to the clutch on the engine. I guess I like my savage to be able to coast freely and not have it feel like the brakes are dragging. My front diff usually goes first due to the back flips.
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Old 02-07-2012, 08:58 PM
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Default RE: Bulletproof differential questions...

Ok guys. Its been a little bit since i started this thread, but I finally made a purchase tonight [8D]

I almost went back with standard gears since they last me decent, but Im sure at 13+ gallons in the spider gears, plastic diff cup, and bearings are getting a little wear on them. It was going to cost me about $16 shipping included to get the ring and pinion gears and nothing else.

However, I ended up ordering a whole bulletrpoof differential with cups, diff case, and shock tower. Ill pull the diff out of the case and put it in my .25 casing most likely and Ill shim it as well. I love the BP gears and doubt ill ever have an issue with them. They will likely pay off in the long run, and ill have new bearings, spiders, aluminum cups, etc...

As for the front, Im going to install the rear diff. Ill roll it by hand and if there is noticeable binding, ill probably just make it 2wd until i want to buy the front diff. However, if it feels fine (and i think it will), then Ill leave the front diff, and BP it whenever it goes out.

Kind of excited to finally be updating the old savage some. Its been loyal and i dont see it going anywhere. I have an Associated .28 in it now and I havent gotten to run it much because of the diff (only a tank or 2 getting it lined out). So im excited to see how its running when i get everything installed and back together. Here is how she sits, waiting on the diff:
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Old 02-08-2012, 11:59 AM
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Default RE: Bulletproof differential questions...

RCU is acting weird...[&:]
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Old 02-08-2012, 01:19 PM
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Default RE: Bulletproof differential questions...

The rear diff casing you purchased is it from a flux or newer type x savage?

If its from the savage x it will have the newer easy access bulkhead, and from the flux it will be easy access along with being made from stronger composite material,

You should just install it as comes into your savage 25, rather than not using the newer style bulkhead,

The only thing you may have to change is the diff cups,
if it has come from a newer savage xl or flux as these will be fitted with the larger hd type cups,

Enjoy wrenching on your truck
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Old 02-09-2012, 08:25 PM
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Default RE: Bulletproof differential questions...

I wondered about the cups. I guess my old cups will swap right in if i need to. I think the ad on ebay just said flux/Savage X bulletproof diff, so im not sure.

Will it drop right in and work with my existing bumper mounts, etc? I know some people before were saying that the savage .25 diff cases were harder to get into, but were a little better design as far as not flexing. I dont plan to need in this differential for a long time, so we'll see. If a stock differential will last my 6-7 gallons, i think this one will go 15 or so

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Old 02-09-2012, 08:59 PM
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Default RE: Bulletproof differential questions...

not sure if the diff case was the same on the .25 as the .21 but if it is you might have to modify the bumpers plate some. When I slapped BP diffs, and the new bulkheads in I couldn't get the bumpers skid plate on, and had to dremel it a bit to make it fit.
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Old 02-09-2012, 09:13 PM
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Default RE: Bulletproof differential questions...

Yeah, I think the .25 chassis is identical to the .21 other than a couple small things. Thats why im thinking i may just stick the whole new diff/ring/pinion in the .25 case, shim it right, and be done with it....
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Old 02-15-2012, 09:13 PM
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Default RE: Bulletproof differential questions...

Ok guys, got some time to fool with the differential tonight. [8D]

Got the old one out and I didnt take it apart, but couldnt see any flat spots on the ring or pinion gears. Started moving the ring gear, and apparently it lost the bearing on the ring gear side and is causing a lot of play. The gears still look pretty good though, I must have shimmed them well, so I believe they will be salvageable for another day

On the other hand, I decided to just stick the whole new BP gear set, X diff case, and shock tower in the truck. The only thing I had to modify was the hinge pin brace for the upper arms. Had to dremel it down some to fit in the space. It was a pretty easy fix though and everything else bolted together perfectly. Luckily I got a diff from an X4.6 truck and the drive cups are the same size as the cups on my old differential, so I didnt have to swap anything.

And man these BP gears are beefy! They look sweet

Anyways, ill try and post some pictures tomorrow, just glad to have her fixed and if its not raining tomorrow when i get home id like to try it out, but chances of that are slim...
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Old 02-16-2012, 01:51 AM
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Default RE: Bulletproof differential questions...


Quote:
ORIGINAL: cummins driver

Ok guys, got some time to fool with the differential tonight. [8D]

Got the old one out and I didnt take it apart, but couldnt see any flat spots on the ring or pinion gears. Started moving the ring gear, and apparently it lost the bearing on the ring gear side and is causing a lot of play. The gears still look pretty good though, I must have shimmed them well, so I believe they will be salvageable for another day
Yea bearing failure is what usually what happens to me. Dont shim it to tight side to side other wise you will put excess side load on them. The newer style bearings are larger on the ring gear side to help with the problem.
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Old 02-16-2012, 06:40 AM
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Default RE: Bulletproof differential questions...

Well, the bearing have about 13 gallons on them so i reckon it was about time. I had it shimmed perfectly when i rebuilt the diff 7 gallons ago. The gears still look really good. I was pretty proud of that since the original differential lasted 5 gallons before stripping the gears with no bearing failure. Apparently i set it up better than HPI did

I was going to shim this new differential, but it felt perfect to me. There is a spot that it gets a little snug, but i figure after the gears wear in to each other it will be perfect. HPI did a good job on the shimming on these BP gear though.
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Old 02-22-2012, 03:37 PM
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Default RE: Bulletproof differential questions...

Some pictures. Also, I have been running fairly heavy tires on this truck all its life. The stock tires and some bigger ones. However, I decided to try my proline holeshots and what a surprise [X(][X(] This thing is a rocket now. Its muuch more nimble. Its a lot more responsive in the steering and the brakes, and the best part is how fast the engine revs. It pulls wheelies easily like this and if its on dirt the tire spin causes the shift to 2nd to happen almost instantly. The RPM the engine pulls up to now is much higher too. I bet it turns 8k more RPM than it did before. This experience alone has sold me on lighter, smaller diameter tires...
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