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rebuilding your diffs video !!!!!!
- Thread starter Jeremy
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shimming your diffs explained: SJ I found this while doing diff. research. hope you don't mind if I put it here.
One of the major steps took when building this version of the BulletProof Savage was the conversion from the stock Savage X “easy access” differentials to the old school Savage Setup - a multi piece, Alloy Metal, differential which included the new Savage X SS alloy diff cups shimmed internally and externally.
The internal shims include thin shims and square shims to make the spider gears inside the diff cups mesh together better. Also, the new alloy diff cups from HPI do not flex! With the older versions of differential cups, they used plastic, which under stress would distort and compromise the mesh of all those spider gears. When that happens, they strip.
An ESSENTIAL step you MUST take if you want rock solid differentials is to shim for side to side clearance. This is BEST done with the alloy diff CASES as opposed to the plastic diff cases because the alloy cases don’t flex, don’t wear at the bearing races, and are generally more ridgid.
To shim the savage differentials, you need to get the hpi hellfire shims, which will take out the clearance between the crown gear and the pinion gear. You want them to mesh to where they are tight, but not crushing up against each other. One shim on the crown gear side and one on the cup side is what worked for me with the GPM diff cases. For you, it may turn out different…but that’s a start!
heres a link to the site I got this from
http://www.ashburg.com/bulletproof/index.htm
One of the major steps took when building this version of the BulletProof Savage was the conversion from the stock Savage X “easy access” differentials to the old school Savage Setup - a multi piece, Alloy Metal, differential which included the new Savage X SS alloy diff cups shimmed internally and externally.
The internal shims include thin shims and square shims to make the spider gears inside the diff cups mesh together better. Also, the new alloy diff cups from HPI do not flex! With the older versions of differential cups, they used plastic, which under stress would distort and compromise the mesh of all those spider gears. When that happens, they strip.
An ESSENTIAL step you MUST take if you want rock solid differentials is to shim for side to side clearance. This is BEST done with the alloy diff CASES as opposed to the plastic diff cases because the alloy cases don’t flex, don’t wear at the bearing races, and are generally more ridgid.
To shim the savage differentials, you need to get the hpi hellfire shims, which will take out the clearance between the crown gear and the pinion gear. You want them to mesh to where they are tight, but not crushing up against each other. One shim on the crown gear side and one on the cup side is what worked for me with the GPM diff cases. For you, it may turn out different…but that’s a start!
heres a link to the site I got this from
http://www.ashburg.com/bulletproof/index.htm
Last edited by a moderator:
some more great info guys, found @ savage central
How-To: Shim A Differential
Why do I need to shim the differential?
The Differential Housing cannot support the diff tight enough to keep the ring-and-pinion gear mesh constant. This can cause the failure of the pinion by breaking off some teeth or cause the ring-and-pinion to skip off each other grinding each gears’ teeth down.
What am I shimming?
You are shimming the differentials' side bearings.
OK lets start…
Parts Needed:
-1 (or 2) completely disassembled differentials
-Shims; There are a few companies that you can get the correct shims from.
GS Racing #GSCST082
HPI #86598
Step 1 (Differential Parts)
To start with you need to have both differentials completely disassembled
Step2 (Shims)
Remove the shims from the pack
Step 3 (Side Bearings)
Now install the differential bearings on the diff cup and ring gear. Make sure you have the bearing on the diff cup pushed all the way on, it will take a little muscle to get it to slide down.
Step 4 (Tip) (Ring Gear Attachment)
The fastest way to find out how many shims you may need on each side of the diff, I attach the ring gear to the diff cup w/ the paper gasket.
The fastest way to do this is to use some 8mm Flathead machine screws.
Attach the ring gear with the two screws opposite of each other
Step 5 (Pinion Install)
Install the pinion in the front half of the housing (GPM/GH housings are cut side-side, stock housings are front-back.)
Step 6 (Diff Install)
With the pinion teeth facing you, install the diff so the ring gear is on the left side of the pinion (For GPM/GH housings: install it on the right and those wheels will go in reverse )
Step 7 (Backlash Test)
Install the back of the housing and slide the diff shafts into the diff (hold the entire unit together)
Now hold the diff shafts and move the diff side-to-side to feel the movement of the diff.
Step 7 (Ring Gear Shim)
Now take the diff out of the housing. Remove the diff shafts, and install 1 shim on the ring gear side bearing. Slide the diff shafts back into the diff and install the diff into the housing.
(With GPM/GH housings just put the shim in the housing where the bearing will sit, then put the diff back in and check for the backlash)
Shim in housing
After you have put 1 shim on the ring gear bearing, put the diff back in the housing halves and check for the movement towards the ring gear. Push the diff away from the pinion, then push the diff towards the pinion. Then determine if you need to shim the ring gear closer to the pinion. If the ring-and-pinion mesh needs to be tighter, add 1 more shim to the ring gear side bearing.
Step 8 (Diff Cup Shim)
OK now that you have the ring gear shimmed into the pinion the way you want, it’s time to shim the diff cup side bearing. You need to do this to prevent the ring gear from being pushed too hard into the pinion.
Just follow the procedure for the ring gear, normally the diff cup side bearing will only need 1 shim.
Step 9 (Completion)
After you shimmed the diff cup side bearing, you have to take the diff all apart and build up the differential.
Remember that when it comes time to install the diff shaft(s) put the shim(s) on the diff shaft then slide the shaft in. You cannot slide the shim over the diff shaft after the diff has been fully assembled.
Step 10
After you diff(s) has been built you will have to line up the shims while you slide the two halves of the diff housing together, go slow and be careful, the shims will bend very easily.
heres a link with pics
http://www.savage-central.com/modules.php?name=Forums&file=viewtopic&t=55122
How-To: Shim A Differential
Why do I need to shim the differential?
The Differential Housing cannot support the diff tight enough to keep the ring-and-pinion gear mesh constant. This can cause the failure of the pinion by breaking off some teeth or cause the ring-and-pinion to skip off each other grinding each gears’ teeth down.
What am I shimming?
You are shimming the differentials' side bearings.
OK lets start…
Parts Needed:
-1 (or 2) completely disassembled differentials
-Shims; There are a few companies that you can get the correct shims from.
GS Racing #GSCST082
HPI #86598
Step 1 (Differential Parts)
To start with you need to have both differentials completely disassembled
Step2 (Shims)
Remove the shims from the pack
Step 3 (Side Bearings)
Now install the differential bearings on the diff cup and ring gear. Make sure you have the bearing on the diff cup pushed all the way on, it will take a little muscle to get it to slide down.
Step 4 (Tip) (Ring Gear Attachment)
The fastest way to find out how many shims you may need on each side of the diff, I attach the ring gear to the diff cup w/ the paper gasket.
The fastest way to do this is to use some 8mm Flathead machine screws.
Attach the ring gear with the two screws opposite of each other
Step 5 (Pinion Install)
Install the pinion in the front half of the housing (GPM/GH housings are cut side-side, stock housings are front-back.)
Step 6 (Diff Install)
With the pinion teeth facing you, install the diff so the ring gear is on the left side of the pinion (For GPM/GH housings: install it on the right and those wheels will go in reverse )
Step 7 (Backlash Test)
Install the back of the housing and slide the diff shafts into the diff (hold the entire unit together)
Now hold the diff shafts and move the diff side-to-side to feel the movement of the diff.
Step 7 (Ring Gear Shim)
Now take the diff out of the housing. Remove the diff shafts, and install 1 shim on the ring gear side bearing. Slide the diff shafts back into the diff and install the diff into the housing.
(With GPM/GH housings just put the shim in the housing where the bearing will sit, then put the diff back in and check for the backlash)
Shim in housing
After you have put 1 shim on the ring gear bearing, put the diff back in the housing halves and check for the movement towards the ring gear. Push the diff away from the pinion, then push the diff towards the pinion. Then determine if you need to shim the ring gear closer to the pinion. If the ring-and-pinion mesh needs to be tighter, add 1 more shim to the ring gear side bearing.
Step 8 (Diff Cup Shim)
OK now that you have the ring gear shimmed into the pinion the way you want, it’s time to shim the diff cup side bearing. You need to do this to prevent the ring gear from being pushed too hard into the pinion.
Just follow the procedure for the ring gear, normally the diff cup side bearing will only need 1 shim.
Step 9 (Completion)
After you shimmed the diff cup side bearing, you have to take the diff all apart and build up the differential.
Remember that when it comes time to install the diff shaft(s) put the shim(s) on the diff shaft then slide the shaft in. You cannot slide the shim over the diff shaft after the diff has been fully assembled.
Step 10
After you diff(s) has been built you will have to line up the shims while you slide the two halves of the diff housing together, go slow and be careful, the shims will bend very easily.
heres a link with pics
http://www.savage-central.com/modules.php?name=Forums&file=viewtopic&t=55122
Last edited by a moderator:
DOOBEEWHA
HPISF languist expert
- Messages
- 1,332
- Location
- Petaluma,Ca,
I would like to say thanks to the both of you two, SJ, and Crash for your finds here.
I find that both of you are very resourceful in helpping and finding
the "BEEF" of a topic more times than not.
I'm Happy to provide some rep points to both of you.
I find that both of you are very resourceful in helpping and finding
the "BEEF" of a topic more times than not.
I'm Happy to provide some rep points to both of you.
thanks doob,
be sure to check out the pics that go with all the info. a picture is worth a thousand words. link below
http://www.savage-central.com/modules.php?name=Forums&file=viewtopic&t=55122
be sure to check out the pics that go with all the info. a picture is worth a thousand words. link below
http://www.savage-central.com/modules.php?name=Forums&file=viewtopic&t=55122
yes thanks for the info guys as i was going to bullet proof my diffs in the near future! so i'll give u some rep points as well cuz it seems u guys spend the time to research stuff so u can really help people in need so thanks!
Last edited by a moderator:
NITROMITE
Well-Known Member
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- Pataskala,Ohio
nice how to
MikeK1981
ChondroManiac
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- Humboldt, CA
Once again, great info guys!
