For those that have shimmed the spider gears

InTheZone

Member
Messages
31
how many shims did you apply to each spider gear?

I'm in the process of building and shimming my BP diff for the first time. I bought extra shims for the area between the housing and bearings and I have that sorted. Very minimal bearing play and outdrive play, any more shims and it may start to bind.

Now while putting together the spider gears I have the blocks the sit on the outside in the correct orientation (flat part against diff housing, smooth/slightly rounded side facing the center of the housing), but I noticed some play between the spider gears or between the blocks or the blocks and the housing.

With one pair of spider gears resting in the diff housing I apply pressure with a screwdriver to the center indentation and take another flathead screwdriver and see if I can gently pry and twist the gaps to check clearances. I have 5 shims on each side so far with enough gap for maybe one more shim on each side, but I don't want to bind it. The reason I apply pressure down the center is to keep the spider gears from rising as I add more shims, and trying to prevent issues when installing the rest of the spider gears. On a stock setup the big bevel gear that sits on the diff outdrive sits flush at the top of the housing when you have all spider and bevel gears installed (ring is off to see the internals). With a diff that has around 5 shims per spider gear the larger bevel gear sits flush at the top of the housing (when the diff is standing up) so I know I didn't add too many shims where the spider gears were binding on each other.

So, is it necessary to add these shims to the spider gear or should I just use one shim per gear? I definitely don't have enough spider gear shims to do more than 1 diff so if it's recommended then I'll need to order more. Thanks

edit: As I just posted this I was thinking about the large washers that rest over the o-ring (between case/ring gear and the large bevel gear) and I believe adding one there would create the same effect that when sandwiched it will push the spider gears towards the outside without needing to add several shims to each spider. Is this thinking correct?
 

ajdragon

Active Member
Messages
96
Hi

I just recently did some shiming to my diff and I add one extra big shim on each side and left the spiders as is.
 

InTheZone

Member
Messages
31
Hi

I just recently did some shiming to my diff and I add one extra big shim on each side and left the spiders as is.
Thanks. Do you also know if there is supposed to be some notchiness to the diff when installed in the diff housing along with the pinion? I have the bulkhead out of the truck and I'm coming from the standard X diff to the BP XL diffs and it just feels slightly notchier, almost like an electric motor spinning by hand. I have yet to put grease on the ring and pinion and there are less teeth compared to the previous setup so maybe that doesn't help with the initial feel.
 

Jam Racing 1

NPTB MONITOR & Master of the known Universe
HPISF Supporter
Messages
4,671
That notchy feel is because you have the diff shimmed too tightly, either in the spyder gears or the side bevel gears.....
 

InTheZone

Member
Messages
31
That notchy feel is because you have the diff shimmed too tightly, either in the spyder gears or the side bevel gears.....
well as of now I only have the single shim placed behind each spider gear and one larger shim placed on the inside of each ring gear and diff cup.

The only shims I have are between the bearing and housing, and bearing and ring gear just to keep the diff from moving side to side, and there are 3 shims on each side. The diff fits right in the bulkhead, no forcing it into place.

edit: I did have a shim on the pinion which I did not use in my previous setup. Maybe I'll try removing and trying again.
 
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