As far as how much.... YOU FILL till it back washes from the fill factory cast hole in the cast iron case.
That's surprising Jim. Been using it for 15 years now. Lots of street driving and 11 second passes. The gear oil I linked does not have additive in it, I added the GM stuff I linked. 1971 Buick 8.5, 30 spline Moser axles, Eaton Posi, Yukon gears, and TA girdle. No issues.
and remember in my post I stated Quote' Remember it is your choice and this is a discussion forum. Use what you feel will do the job.' We are all here to give our opinions and discuss the topic. I am just giving my experiences with the product and my opinion. That is all it is. It is not to say that for someone else it worked fine for. Same with BREAK IN procedures. Mine is not the only way, you can do 20min drive like Richmond has in their instructions etc. Cam shaft too...says 20mins at 2000 rpms etc. I do not do that one that way either. If you have something that works then you use it. We have always had Chatter issues with valvoline gear oil no matter what additive and how much we install. We used all the other oils NO ISSUES with chatter...??? This is what works for us. This is what we do. I can believe you use it and it works. I have just given up hope on that company. Sorry. Not mad just talking and discussing. Have a good spring Guys / Gals enjoy as much as you can with the prices so high BUT do not give up the hobby! Fight for your Gas guzzler! Especially all of us that are actually working for a living... or have worked for a living... lol. Jim JD Race
Ya oil... I have had the best luck in differentials over the years with Richmond GL-6 gear oil.. But I am sure plenty of stuff out there "works".. Reading this thread has me somewhat dismayed.. 3.08 to 3.31 is not going to yield much difference in performance in that car. I would have recommended a 3.55 for that 12 bolt.. this is not too much for occasional highway driving at 70-75 mph.. and half a turn in the rear will certainly register on the butt-dyno. This whole "keep the 3.08 or whatever highway gears, because of the Buick torque" is a myth.. not sure who started it, probably somebody with a 3.08 rear. Ask yourself.. what did Buick do to make the GS faster... gears Stock Stage 1 with no ac gear.. 3.64 ----------------------------------- Now personally, I would have told him to put the rear end tools down, the culprit that is killing your performance is that ST-300.. a switch to the TH 350 or 400, with one of my 9.5" converters would make a HUGE difference in that car.. and your just a 4 barrel intake and Q-jet from having something pretty solid in performance. .2 of a gear change?.. not a good cost-effort/result ratio.. I have been down this road with the 2 speed 68 Skylarks... customer wanted the gears changed.... He had a 2.93 10 bolt, so we swapped in a 3.42 8.5" rear from a later GS.. That made a noticeable difference.. But nothing compared to the switch to the 3 speed trans.. and this was way back in the early 2000's, before I was selling converters.. so it had a slightly looser 12" unit in it.. would have been so much better with my 9.5".. Of course the best of both worlds here is the use of a 4 speed OD trans, in conjunction with a 3.73 or 3.90 gear.. ya, lot bigger expense, but we are now talking about a whole different car in performance, that still cruises on the highway at a comfortable rpm at 75mph.. And I have a 9.5" combo for that too.. Anyway... just a few thoughts.. JW
Thank you for the replies , it might be helpful for others in the future as well . I know the tranny would be the thing to do I've been told multiple times but it's not for now ... the reason I'm "upgrading" the gear is only because I have to replace the cover (broken) .... and while it's open it's time to refresh bearing and stuff in it .... I looked for the 4 bbl upgrade too couple years ago but I kept my leisure money to bought a new edge (ragtop) last year Don't want a 10 seconds car either so even if it's not a huge performance gain it will be just good enough for my use .... next gear upgrade will be for the pony (3.73 / 3.90) Will keep you update later on
My general rule of thumb is to skip at least one ratio to justify the time and cost of a gear swap. If you have 2:73’s,skip a 3:08 and get a 3:23 at the least. If you have a 3:23,skip a 3:42 and get a 3:55,3:64,or 3:73,depending one what rearend you are working with. If you have ANY future plans to get an overdrive of some sort,get that figured out and build the rear once,accordingly.
I went OVERDRIVE and I will not even go back to a 3 speed AUTO or 4 speed manual ...lol. So thinking about a 2 speed is TOTALLY out of the question. Bracket racing is what those are for....lol. Jim The day of 50 cent a gallon has long past 2-3 generations....Get in the NOW. ...Your going to spend money one way or the other. I can drive my car anywhere 70-80 easy low RPMS and still run 12s down the track. Gas mileage is a moot point with big blocks so I will not make that point for me.... Get that car out and drive them before they out law or TAX THE CRAP out of them for being on the road...GOD I hope they are not reading this...BAD IDEA there.
Good for you , you seems to know your stuff but we don't have to agree on all point. If it ain't broke don't fix it they say ... I'll stay with my ST300 as long as it works fine, nothing wrong there. Went only once on a track in 19 years so i don't (give a) care 'bout that. Je ne suis pas un adepte de la pensée unique mais j'aprécie vos conseils lorsque requis en demeurant dans le respect des autres aussi , bonne journée ! ;-)
Your choice Go to at least 3.42 gear from 3.08, you probably wont find much performance difference with the change, just increased RPM. Id change to a T 350 trans first before gears
Yes MY choice ... but what you don't get is that its not about performance (or so few) I all explained this earlier on dirais que vous ne prenez pas le temps de lire It just getting better , thank you for your support mais ca va être correct comme ca ! Sujet clos en ce qui me concerne Keep you update with my appreciation later on. Keep an eye on this post
Buddy of mine took over his family owned garage about 30 years ago, which he recently sold out and retired from. He told me he and his old man had decided long ago to use GM diff lube and posi additive at in any rear they worked on and its what he swore by. He could go on and on about 2000s Chrysler trucks having crappy rear oils and wasting gear sets. Curious if you had a favorite?
Your buddy and his old man were correct, that GM differential oil and the additive were the best bar none but the average guy could not afford it. It came in less than a quart plastic bottles (back when oil still came in cans) had no SAE designation on the bottle and was the only oil that would significantly reduce the sound from a Dana 60 and cost more than the new gear set you just put in. Well almost anyway.
Job Done this week-end ! Doesn't have much time to test it so far but I notice only good things so far ... First I now have a chromed unbroken diff cover I found out that I have a positraction old oil seems to avoid the system to work properly ! And the most notable thing is the noise who disappear due to the new bearing who were shut, I wonder where that annoying sound came from ... Need to test it more to see if gear speedo need to be replace but so far only good things to say about this "update" , performance wise it's too soon to tell but at first take it seems marginal but just enough for me .
En plein ca mon ami tu as tout compris ... mais surtout des nouveaux bearings qui ne grondent plus quand j'accelère, juste pour cela ca en valait la peine !
Why is there a gov-lock unit in your 12-bolt Chevy car rearend? Someone obviously swapped that in there at some point. Probably from a Truck.
Did ANY 12 bolt Chevy car rears or even the light truck come with the Gov Loc?? I thought they were all clutch type?
LOL. Yah that ain't right...lol. Something is a miss. THAT IS WHY WE SAY send pictures so we can help. Guess you will be in that rear again real soon. Jim
10 bolt 8.5, 12 bolt chevy truck, 7.5, 7.6, dana 45 all had Auto locker gov lock units These units are good for regular driving vehicles BUT not tire burning hot rods.
