jdoyle

iTrader: (27)

Can anyone confirm/deny that there are two different LS1 f-body alternator brackets? I have a part number 12556916 as the original design and 12563327 as the second/updated design. The thing is, I can't a shred of information on this site or google on GM part number 12556916.

Could the swap gurus shed some light on this for me please?

Thank you

bczee

iTrader: (12)

I beleive that the #12556916 number was Superseded with #12563327, should be the same part and application. If anything, maybe a different casting, but intended as a direct replacement.

If you need to confirm. try calling your local GM Dealer and question it with the parts tech. They usually will have all of the part numbers and history if Superseded and what it replaced. At least the guy I used to deal with would help on these issues.

I know my 99 PS pump and bracket differ from my 02 setup.

BC

jdoyle

iTrader: (27)

You are correct, GM PN 12556916 was superseded by GM PN 12563327, as confirmed by a guy in the parts department of Friendly Chevrolet in Dallas.

Please refer to post #5

Then I ready post #5 in the above link which makes me think that this cannot be interchanged. Cant use 12556916 (first design) and 12563326 (second design idler) and 12563327 (second design bracket) with 12564401 (first design).

EDIT: I think I have it figured out. Both brackets will work on the aluminum block of an ls1 fbody. The first design bracket (12556916) has been replaced with the second design bracket (12563327). GM doesnt sell 12559616, however, they do sell 12563327. They also still sell both idlers, there was no superseding of idlers (in case you need an idler for your first design bracket). What is said in post #5 is true, first design parts must only be used with first design parts and the same goes with the second design.

Thanks bczee!

-TheBandit-

iTrader: (1)

You can get the idlers much cheaper online or through a local parts store than what GM sells them for. I eventually broke down and bought a new bracket from GM because they aren't coming up used as often as I'd like.

FWIW the newer alternator brackets on the 2010 Camaro are not interchangeable with the old f-body ones.

KissMyWhiteSS

iTrader: (3)

There was a TSB to replace the alternator bracket for 98 and 99 f-bodies.

TSB 00-06-01-008 of MAR 00 states that:
"Cause: The serpentine belt squeak/chirp noise may be caused by misalignment between the idler pulley and the crankshaft pulley. A slight rocking motion of the idler pulley causes the misalignment, which results in noise."

"Correction: To correct this condition on vehicles built prior to the VIN breakpoint (VIN breakpoint Y2107225 with 5.7L V8 Engine) install the new generator bracket, double row idler pulley and serp. belt..."

"Important: This new generator bracket can be identified by the depth of the idler pulley mounting pilot. The pilot dimension on the new generator bracket is 10 mm. The previous bracket was 8.3 mm."

The new parts that you need are PN# 12563326 Double Row Idler Pulley Assembly, PN# 12563327 Generator Bracket, & PN# 12562626 Serpentine Belt.

bczee

iTrader: (12)

good info. thanks..

Accrdwgnguy

Before I order these brackets, is 12556915 the correct part number for the rear bracket that works with the 2nd design bracket?

GM still carries both brackets, and they are relatively inexpensive.

johnp94

iTrader: (12)

Am I disregarding my old dust cover from the old idler pulley I will replace with the double row idler pulley ? Same size bolt or different ? Any other pieces neede to make it spin freely like my old idler pulley ?