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2013-14 Shelby GT500
Putting in 3.73s in a couple of weeks. Few questions...
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<blockquote data-quote="jchristena" data-source="post: 15649224" data-attributes="member: 143838"><p>Well, I'll report back on this with my results and a few questions in case anyone wants to chime in. I already PM'd Snoopy and BiminiLX. I also poured over the existing 3.73 gear noise thread. My main difference is I reused my bearings and factory shims to achieve .008 backlash...so my carrier bearing preload should be factory. Anyway...here's my findings.. And yea, I know this has been beat to death. </p><p></p><p>The 3.31s were quiet but just had a little slop. I measured about .014 backlash before I took them out. With these new gears, I have a whine on light acceleration after about 55mph+ in any gear. </p><p></p><p>-Reused the same bearings on everything as they looked perfect. Just cleaned them out real well before reinstalling. </p><p>-Pinion depth was pretty close w/ the factory shim. Factory was .032. I added .002 for a total of .034. Preload feels really good. No slop in the pinion at all. Near as I can tell, preload is around 22lbs which seems to be within Ford spec. If preload wasn't enough, I would THINK i'd be getting a whine on deceleration instead. New crush sleeve of course.</p><p>-Gear wear pattern looks perfect. Had a buddy of mine look at the wear pattern and he's been doing the racing thing for 55 years...countless 8.8s. Said it looks perfect to him.</p><p>-Backlash. I have it set at .008. With the factory shims, I was closer to .012-.014. The shim on each side were so close in thickness, I just swapped them and that closed it down to .008. I was pretty happy about this because this should maintain the identical carrier bearing preload on these used bearings as it was from my quiet factory rear end.</p><p></p><p>The gears were quiet as hell for the first 20 miles. I have about 30 miles on the gears now and the whine has just creeped in. </p><p></p><p>-I'm going to tear this down tomorrow again but can excessive backlash(and probably not a ton of it) cause noise?</p><p>-Would you replace the carrier bearings even if they look perfect? It was of course preferable to leave them as we had a known shim thickness to give the factory preload value. I guess better too much preload than too little from what I've read.</p><p>-After 30 miles, assuming that maybe it's backlash, would you replace these 3.73s w/ new ones? Or do you think that's few enough miles that they might be fine. There are no hard launches or anything. I think I stepped on it in second and third maybe 1 time w/ street tires...so no severe duty or anything.</p><p></p><p>Anything you can think of or offer I would greatly appreciate. I can't over emphasize how much I'm looking forward to tearing this down again tomorrow in the Texas heat. <img src="data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7" class="smilie smilie--sprite smilie--sprite1" alt=":)" title="Smile :)" loading="lazy" data-shortname=":)" />...but definitely don't want to queue up for a 3rd or 4th time after this.</p></blockquote><p></p>
[QUOTE="jchristena, post: 15649224, member: 143838"] Well, I'll report back on this with my results and a few questions in case anyone wants to chime in. I already PM'd Snoopy and BiminiLX. I also poured over the existing 3.73 gear noise thread. My main difference is I reused my bearings and factory shims to achieve .008 backlash...so my carrier bearing preload should be factory. Anyway...here's my findings.. And yea, I know this has been beat to death. The 3.31s were quiet but just had a little slop. I measured about .014 backlash before I took them out. With these new gears, I have a whine on light acceleration after about 55mph+ in any gear. -Reused the same bearings on everything as they looked perfect. Just cleaned them out real well before reinstalling. -Pinion depth was pretty close w/ the factory shim. Factory was .032. I added .002 for a total of .034. Preload feels really good. No slop in the pinion at all. Near as I can tell, preload is around 22lbs which seems to be within Ford spec. If preload wasn't enough, I would THINK i'd be getting a whine on deceleration instead. New crush sleeve of course. -Gear wear pattern looks perfect. Had a buddy of mine look at the wear pattern and he's been doing the racing thing for 55 years...countless 8.8s. Said it looks perfect to him. -Backlash. I have it set at .008. With the factory shims, I was closer to .012-.014. The shim on each side were so close in thickness, I just swapped them and that closed it down to .008. I was pretty happy about this because this should maintain the identical carrier bearing preload on these used bearings as it was from my quiet factory rear end. The gears were quiet as hell for the first 20 miles. I have about 30 miles on the gears now and the whine has just creeped in. -I'm going to tear this down tomorrow again but can excessive backlash(and probably not a ton of it) cause noise? -Would you replace the carrier bearings even if they look perfect? It was of course preferable to leave them as we had a known shim thickness to give the factory preload value. I guess better too much preload than too little from what I've read. -After 30 miles, assuming that maybe it's backlash, would you replace these 3.73s w/ new ones? Or do you think that's few enough miles that they might be fine. There are no hard launches or anything. I think I stepped on it in second and third maybe 1 time w/ street tires...so no severe duty or anything. Anything you can think of or offer I would greatly appreciate. I can't over emphasize how much I'm looking forward to tearing this down again tomorrow in the Texas heat. :)...but definitely don't want to queue up for a 3rd or 4th time after this. [/QUOTE]
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2013-14 Shelby GT500
Putting in 3.73s in a couple of weeks. Few questions...
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