Ring gear runout
II ought to learn by now not to post in these threads. It haunts my thoughts when i dont see or here the solution. Are the gears brand new or used? Are the bearings brand new or used?
I have had used bearing installs where the race no longer is true and caused excessive run out. To save money I used to advise people to take complete gear, carrier and bearings out of a donor diff and reinstall in the diff you want to run but now I recommend brand new bearings every time you pull it apart. Timken or nothing as well. This is the only way to get them really true. So thats my first curiosity. Second if the gears are used Im wondering if the pinion is bent a little causing the backlash issue. So if the bearings are used, replace them all and go again. If the gears are used i'd look there next. Occasionally a carrier or two gets worn out of service as well. The ring gear MUST be tight going on, no slip fit here it must be tight enough that some soft faced rubber hammer or wood and hammering is required to get it seated on the carrier but this would reveal in your run out tests so I doubt thats the case here. Let us know what you find
I have had used bearing installs where the race no longer is true and caused excessive run out. To save money I used to advise people to take complete gear, carrier and bearings out of a donor diff and reinstall in the diff you want to run but now I recommend brand new bearings every time you pull it apart. Timken or nothing as well. This is the only way to get them really true. So thats my first curiosity. Second if the gears are used Im wondering if the pinion is bent a little causing the backlash issue. So if the bearings are used, replace them all and go again. If the gears are used i'd look there next. Occasionally a carrier or two gets worn out of service as well. The ring gear MUST be tight going on, no slip fit here it must be tight enough that some soft faced rubber hammer or wood and hammering is required to get it seated on the carrier but this would reveal in your run out tests so I doubt thats the case here. Let us know what you find
Thread Starter
TECH Apprentice
Joined: May 2015
Posts: 367
Likes: 5
From: connecticut
II ought to learn by now not to post in these threads. It haunts my thoughts when i dont see or here the solution. Are the gears brand new or used? Are the bearings brand new or used?
I have had used bearing installs where the race no longer is true and caused excessive run out. To save money I used to advise people to take complete gear, carrier and bearings out of a donor diff and reinstall in the diff you want to run but now I recommend brand new bearings every time you pull it apart. Timken or nothing as well. This is the only way to get them really true. So thats my first curiosity. Second if the gears are used Im wondering if the pinion is bent a little causing the backlash issue. So if the bearings are used, replace them all and go again. If the gears are used i'd look there next. Occasionally a carrier or two gets worn out of service as well. The ring gear MUST be tight going on, no slip fit here it must be tight enough that some soft faced rubber hammer or wood and hammering is required to get it seated on the carrier but this would reveal in your run out tests so I doubt thats the case here. Let us know what you find
I have had used bearing installs where the race no longer is true and caused excessive run out. To save money I used to advise people to take complete gear, carrier and bearings out of a donor diff and reinstall in the diff you want to run but now I recommend brand new bearings every time you pull it apart. Timken or nothing as well. This is the only way to get them really true. So thats my first curiosity. Second if the gears are used Im wondering if the pinion is bent a little causing the backlash issue. So if the bearings are used, replace them all and go again. If the gears are used i'd look there next. Occasionally a carrier or two gets worn out of service as well. The ring gear MUST be tight going on, no slip fit here it must be tight enough that some soft faced rubber hammer or wood and hammering is required to get it seated on the carrier but this would reveal in your run out tests so I doubt thats the case here. Let us know what you find
If the carrier was wonky you could see that in run out which you dont. If the spacer was wonkey you would see that in ring gear run out which is where I would put my focus and check that again. I have had a carrier that wasn't tight fitting to the ring that no matter what I tried kept running out over 4 thou which will affect backlash so im thinking look closer into that.
If a gear was dropped or nicked in shipping this is possible but typically a nicked gear shows one or two wonky tooth contacts and the rest are normal. If its wobbling off axis then its not running concentric which points to the ring gear installation or a bent pinion which I have seen a few times, especially common with torque arm diffs because of housing strain. I have seen plenty of snapped pinions because of this, broke some myself too.
Referring back to post # 9, Richmond Excel gear set. those are about $100 cheaper than the standard sets at Summit. I'm suspecting those are the culprit. Some threads on car forums indicate/state they're of Chinese manufacture.
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TECH Apprentice
Joined: May 2015
Posts: 367
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From: connecticut
yeah I might b better off with something better....haven't cheaped out on this build so I might as well get a better gearset.
There's no reason to be dead set on 3.90s'. Only possible reason is for drag racing as to go to the 'traps' at a specific rpm.
Richmond is the only choice for a 2 series carrier, a 'thick' set not requiring a spacer,at about $100 more than the 'excel' set.
Motive has 3.90s' but not for 2 series,3 series only. Motive is a popular brand here on ls1tech,probably the most popular brand.
I use richmonds,even used sets. I set them up for maximum strength pattern and disregard noise. I'd rather have a set that won't wear out and noisy than a set that's quiet and won't last long.
Richmond is the only choice for a 2 series carrier, a 'thick' set not requiring a spacer,at about $100 more than the 'excel' set.
Motive has 3.90s' but not for 2 series,3 series only. Motive is a popular brand here on ls1tech,probably the most popular brand.
I use richmonds,even used sets. I set them up for maximum strength pattern and disregard noise. I'd rather have a set that won't wear out and noisy than a set that's quiet and won't last long.
Thread Starter
TECH Apprentice
Joined: May 2015
Posts: 367
Likes: 5
From: connecticut
There's no reason to be dead set on 3.90s'. Only possible reason is for drag racing as to go to the 'traps' at a specific rpm.
Richmond is the only choice for a 2 series carrier, a 'thick' set not requiring a spacer,at about $100 more than the 'excel' set.
Motive has 3.90s' but not for 2 series,3 series only. Motive is a popular brand here on ls1tech,probably the most popular brand.
I use richmonds,even used sets. I set them up for maximum strength pattern and disregard noise. I'd rather have a set that won't wear out and noisy than a set that's quiet and won't last long.
Richmond is the only choice for a 2 series carrier, a 'thick' set not requiring a spacer,at about $100 more than the 'excel' set.
Motive has 3.90s' but not for 2 series,3 series only. Motive is a popular brand here on ls1tech,probably the most popular brand.
I use richmonds,even used sets. I set them up for maximum strength pattern and disregard noise. I'd rather have a set that won't wear out and noisy than a set that's quiet and won't last long.
3.90s', 2 series, no spacer, you're stuck with Richmond.
I think you're being too picky about highway rpm. For example 2600 with 4.10 would change to 2473 with 3.90. Only 127rpm difference.
I run 4.56s and on long Ohio to Florida trips.
I think you're being too picky about highway rpm. For example 2600 with 4.10 would change to 2473 with 3.90. Only 127rpm difference.
I run 4.56s and on long Ohio to Florida trips.
You will not be able to tell a difference between 3.73 and 3.90 at all. Even a slight tire diameter change will be more noticeable. For street I use the 3.73 pretty much exclusively now and its what I recommend with a 6spd especially and with a 4spd auto I suggest 3.55. The performance difference is soooo slight between them all and the ease of driving is very noticeable. 4.10, 4.56, 4.88 been there done that, learned better. Unless you are racing with a program and a targeted trap RPM then in all situations save for the most radical cams which are useless on the street there is no need for more gear than 3.73 imo.
Chasing numbers gets very compromising either with hp or track times. Trap speed tells the tale and that wont change much from ratio to ratio
Chasing numbers gets very compromising either with hp or track times. Trap speed tells the tale and that wont change much from ratio to ratio
Thread Starter
TECH Apprentice
Joined: May 2015
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From: connecticut
Update So after the rear sitting with that subpar pattern i got a chance to pickup a used Detroit trutrac diff. I reinstalled everything onto the new diff and made several adjustments to pinion depth, removing most of my spacers and got a nice centered pattern with less than .001 runout and .008 backlash. Going to press on bearing tomorrow and then I'll post pics of my pattern.
what size shim do you guys think I should add for my carrier preload? I have read you physically cant really give it too much preload unless your using a housing spreader.
what size shim do you guys think I should add for my carrier preload? I have read you physically cant really give it too much preload unless your using a housing spreader.
Thread Starter
TECH Apprentice
Joined: May 2015
Posts: 367
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From: connecticut
You will not be able to tell a difference between 3.73 and 3.90 at all. Even a slight tire diameter change will be more noticeable. For street I use the 3.73 pretty much exclusively now and its what I recommend with a 6spd especially and with a 4spd auto I suggest 3.55. The performance difference is soooo slight between them all and the ease of driving is very noticeable. 4.10, 4.56, 4.88 been there done that, learned better. Unless you are racing with a program and a targeted trap RPM then in all situations save for the most radical cams which are useless on the street there is no need for more gear than 3.73 imo.
Chasing numbers gets very compromising either with hp or track times. Trap speed tells the tale and that wont change much from ratio to ratio
Chasing numbers gets very compromising either with hp or track times. Trap speed tells the tale and that wont change much from ratio to ratio