kreed

Ring and pinion gear for 65 GS

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Tore into my differential today and am being told that my ring and pinion gear is garbage need to be replaced . It is a 3.42 Positraction . Any suggestions on where to get this ? Found a 3.55 that supposedly fits a 65 GS . Other than running my rpm up a little at highway speed , what would be the down side ? I know NOTHING about these things so excuse my stupid questions . Obviously would prefer to have the 3.42 but a quick search so far has struck out . Any help would be greatly appreciated . Thanks 

KReed

ROA 14549

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Benefits of AACA Membership.

Nobody makes ring and pinion sets for our cars.  I would get a second opinion on if your gears are totally trashed or not. 3.42 is one of the hardest to find and the most expensive.  I might have a 3.07 set coming out of a 64 parts car if need it.  

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If the 3.55 is for a GS from the Skylark series, it won't fit; it's much smaller.  Probably an 8.2" instead of the 9-3/8" as is in the 1st generation Rivieras.

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7 hours ago, DualQuadDave said:

Nobody makes ring and pinion sets for our cars.  I would get a second opinion on if your gears are totally trashed or not. 3.42 is one of the hardest to find and the most expensive.  

Agree - got any pics showing why they are bad Ken? It is uncommon for the ring and pinion set to be damaged in a Riv.

I definitely would not go higher numerically. 3.42s are bad enough on the highway as it is.

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Thanks for everyone's  input. Going over tomorrow to look for myself at the gears - just going by what I have been told by the guy who tore it down. He said that several of the splines on both the ring and pinion were damaged - not sure how it would happen but he said someone has definitely " been in there at some point" . Way over my pay grade but will get some photos and try to post them . 

KReed

ROA 14549

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A 3.55 gear set was NEVER available for a 9 3/8" big car diff.

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Thanks much  -will continue to explore options  and any suggestions as where to find one or an alternative greatly appreciated .

KReed 

ROA 14549

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12 hours ago, JZRIV said:

Agree - got any pics showing why they are bad Ken? It is uncommon for the ring and pinion set to be damaged in a Riv.

I definitely would not go higher numerically. 3.42s are bad enough on the highway as it is.

I`ve seen on several occasions the bolts for the ring gear loosen and fall out. When the stray bolt(s) get caught between the gears the teeth chunk/chip out....not good

  Tom

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Tom - I think that is exactly what happened. My guy  said there were two loose bolts in the casing when he opened it . Apparently chewed up a couple of the splines on the pinion gear .mi am going to look at it tomorrow and might put up a couple of pictures  . Ken 

Edited by kreed
Spelling error (see edit history)

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7 hours ago, kreed said:

Thanks much  -will continue to explore options  and any suggestions as where to find one or an alternative greatly appreciated .

KReed 

ROA 14549

There is a vendor from Michigan that advertises in the Riview that HAD one from a '65 GS he parted a while back. He offered it to me but I was not interested, you might check with him and see if it is still available.

 

PM me if you need his name and or contact info. I am not saying I would endorse him, but he told me he had one available and is usually reliable in that way.

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1 hour ago, kreed said:

Tom - I think that is exactly what happened. My guy  said there were two loose bolts in the casing when he opened it . Apparently chewed up a couple of the splines on the pinion gear .mi am going to look at it tomorrow and might put up a couple of pictures  . Ken 

I cant see a loose bolt damaging an area of the splines that would matter but who knows? My guess is the damage is elsewhere.

If the lead that Randall supplied doesnt pan out I can also provide a lead.

  Tom

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Thank Tom - just sent you a PM . Ken Reed

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I had bolts on my 3.42 Wildcat gear back out ... started making noise on the way to Bowling Green GS Nationals.  I stopped on the highway to check it out and the car would not roll forward after I stopped.

I rolled it backwards once and then could roll forward so I drove on to the show.  I left the show in terrible rain and stopped traffic, drove all the way to Cincinnati OK.

When I got into town I thought I sure missed that drag racing, so I nailed it and poof, no more power.  

So Close, but the last 5 miles were on the trailer!  pulled the rear apart and the ring bolts had all backed out, there must have been 3 left holding the ring gear and when I nailed it they sheared off.

Surprisingly there was no damage to the gears and they are back in the car!

 

I have offered the 3.42:1 posi rear in my parts pile for $650 if you need a whole unit.  

 

Ted

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12 hours ago, Rivman said:

There is a vendor from Michigan that advertises in the Riview that HAD one from a '65 GS he parted a while back. He offered it to me but I was not interested, you might check with him and see if it is still available.

 

PM me if you need his name and or contact info. I am not saying I would endorse him, but he told me he had one available and is usually reliable in that way.

Ha Ha :)  A character for sure.

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Thought I would post a few pics of my differential after it was taken apart. Four of the bolts  that secure the ring gear were completely out and ground up and laying in the bottom of the housing . Three of the remaining bolts were loose and  could be unscrewed with my fingers . At least 4 or 5 of the splines on the pinion gear are damaged although difficult to see on the pics . The splines on the ring gear look OK .There was also some evidence  of some minor damage to the housing where the bolts had been banging around . There is no question that they damaged the pinion gear . Why this happened I have  no idea . This is a 60K mile car but maybe driven hard at one time ?... Does vibration cause the bolts to back out?  .... Are these bolts normally torqued ? 

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Ken, when you state "splines" are you referring to the gear teeth? Keep in mind the gear teeth do not contact one another across the entire tooth. The contact pattern changes with torque applied but not across the entire surface of the teeth. So, if the bolts chipped the ends of the teeth you might be lucky enough that the damage will not matter.

  Tom

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                      Great, now I have something to worry about on my car! Does anybody know how common this problem is?

Obviously those bolts weren't torqued properly at the factory.

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2 hours ago, 1965rivgs said:

Ken, when you state "splines" are you referring to the gear teeth? Keep in mind the gear teeth do not contact one another across the entire tooth. The contact pattern changes with torque applied but not across the entire surface of the teeth. So, if the bolts chipped the ends of the teeth you might be lucky enough that the damage will not matter.

  Tom

Thanks Tom - that is very good to know and makes perfect sense. And yes , splines = gears . Appreciate the advice. 

KReed

ROA 14549

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58 minutes ago, Seafoam65 said:

                      Great, now I have something to worry about on my car! Does anybody know how common this problem is?

Obviously those bolts weren't torqued properly at the factory.

 ^^^^^ what he said

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1 hour ago, Seafoam65 said:

                      Great, now I have something to worry about on my car! Does anybody know how common this problem is?

Obviously those bolts weren't torqued properly at the factory.

It happens...see post #8. Cant remember what year Buick changed the ring gears but at some point they went to left hand threads for the ring gear bolts to prevent this issue. 1967? Tom T?

 

  Tom

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3 hours ago, Seafoam65 said:

 

Obviously those bolts weren't torqued properly at the factory.

 

Not necessarily so. I have always used thread locker on these bolts to prevent them from backing out, as you have experienced. 

 

From what i can see in your pics, it appears to be only the outer parts of a few teeth  on the ring that are damaged. For the purpose of daily driving and cruizing the gear would be fine. If it were disassembled it, i would grind off the rough outer edges. 

Edited by still looking (see edit history)

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I've NEVER had it happen to any rears I did. Then again I ALWAYS use red or green Loctite & torque to 5 or so pds. Above recommended torque.

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18 hours ago, still looking said:

 

Not necessarily so. I have always used thread locker on these bolts to prevent them from backing out, as you have experienced. 

 

From what i can see in your pics, it appears to be only the outer parts of a few teeth  on the ring that are damaged. For the purpose of daily driving and cruizing the gear would be fine. If it were disassembled it, i would grind off the rough outer edges. 

 All this advice appreciated . The damage is only on 4-5 of the pinion gear . Perhaps Will try the suggestion of grinding off a few of the rough spots . Is it true that if you do replace the differential , you should always have a "matched " set of ring and pinion gears and not just replace a pinion gear ( assuming you could find one ) ?  Aren't these machined identically ? And therefore work with any other ring gear .? Thought it was a little weird that you couldn't interchange them but these kinds of things are well over my pay grade . Thread lock is a great idea. Thanks for all the comments.

KReed

ROA 14549

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30 minutes ago, kreed said:

 All this advice appreciated . The damage is only on 4-5 of the pinion gear . Perhaps Will try the suggestion of grinding off a few of the rough spots . Is it true that if you do replace the differential , you should always have a "matched " set of ring and pinion gears and not just replace a pinion gear ( assuming you could find one ) ?  Aren't these machined identically ? And therefore work with any other ring gear .? Thought it was a little weird that you couldn't interchange them but these kinds of things are well over my pay grade . Thread lock is a great idea. Thanks for all the comments.

KReed

ROA 14549

Correct, ring and pinion do wear together so they need to be replaced together.  In the case of Riv gears, everything is used, so if had to buy some, it would be a complete diff anyway. I would take the chance and rebuild what you have.  The mesh pattern looks good from the pics and I would call the damage not horrible.   For what it costs to buy one($1000+), I would at least try to salvage what you have. JMO

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As stated, it would be chancy just replacing the ring with another used ring gear.

Alternatively you could replace them as a set, used.

The posi is the gem. If you had an open diff with the gears you like then (I think, there was a case of different carriers with more race gear sets in chevs, maybe not in Buicks) you could replace the carrier (the open) with your posi. ad use those gears.

Setup is not that difficult.

But just use the gears you have now. Should be fine

Hope this helps

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