Ok so im not a pro by all means here. Our resident pros are monzas , 507olds, and Bob kelso who is on here butdoes not chime in much. In the past he has done 2 diffs for me before I ventured on my own. This thread is how I break down the swap. Guys feel free to chime in with your opinion. I did an 8.5 10 bolt on my fiancés k5 blazer with help from the guru's here. Im doing this because I have not yet seen some what of an instructionary thread. Many question threads that turn into a build thread.


Ok so my current project is a simple gear swap no posi. Going from a 2.41 to a 3.23 or 3.42 I forgot what I bought lol.


First step is to pull the cover off and sping it to find the numberic numbers on the gear which in my case was 41 17 . That means 41 teeth on the ring gear and 17 on the pinion. Usually these numbers on the ring gear on the flat surface of the diameter near the mount surface. Now this gear set is a used gm set so checking the pattern is a little different since you have to go by the coast side vs. the drive side which is common for a new set. Now I cannot use this carrier so im going to use a 3 series carrier. There is spacers but I see it as a band aid. The reason for the difference in carriers is the pinion size. For example with the 41 to 17 the pinion is huge compared to a 41 to 11 so the side to side mount distance is different on the 17 tooth pinion it will be closer to the dr. side of the rear end since the diameter of the pinion is much bigger. Now if you mounted an 11 tooth pinion on there there with out changing the carrier the teeth would not have the proper mesh. Btw this is how I interpret the whole difference between the difference in carriers. I will show pics as i go of what is what . Again I'm no pro but sometimes the less blind need to lead the blind lol.

 

Thanks for the thread copper I'm a follower here for sure !!

 

X2. Thanks Copper. This should be a good read.

 

Thanks copper hope to lean so I can tackle my own soon

 

Guys this was the thread for the 8.5 I did on my fiancés k5 blazer. The pics are gone but I asked some somewhat detailed questions. I will cover the stuff I had issues with. Just thought id post up this thread for reference.


https://classicoldsmobile.com/forums...5-10-bolt.html

 

Looks like Your right on track. I did run one of them spacers for years and no problems but if you have the right carrer just change it. I've Done a few if you have any questions just ask. JJ

 

i got that carrier for you about an hour ago. do you want me to mail it? I can bring it to Howard's garage too if that's a shorter drive for you. I'll be at josh's shop all week building the apartment .

 

Copper your garage appears to have grown a LOT since last I was there...nice lift to work off of, Better than the cold cement. Looking forward to this one, thank you!

 

Paladin that's my dads car on the lift at his work his boss used to store his 63 split window vette there over the winter now I use it lol.

 

NICE...and it looks WARM, double fist pump!

 

No need to mail it. I can swing by josh's place sometime next week. I don't know how late you will be there but I can head out that way anytime after 6. If not I can pick up from your place.

 

My garage just hit 32 degrees which its comfortable to work in. Last time I did the rear end gears on the blazer I think it was in the 30's and I was bustin a sweat with the halogen lights on me lol.

 

Ok I got my carrier from j-Chicago. I thought I would e able to get it done this weekend but my lack of planning and crappy weather have made me push for next weekend. Im going to mention a few things like tools you will need. If you have an air compressor a good impact and big socket set its big plus ., it will help out big time specially for the crush sleeve and removal of the pinion nut. If you don't have an air supply you will need a big pipe wrench to hold the pinion yoke to bust off the pinion nut and to set the crush sleeve. You will also need access to a press. The carrier bearings are pressed on and there are specific tools to remove them but if you get creative enough you can take em off with out a bearing separator and press. You will also need a spare pinion bearing or to remove the old one off of you old pinion. You take a die grunder and hog it out so you can slip it on and off of the pinion to set pinion depth. Once you achieve it you go ahead and press the new bearing in with the shims you achieved your depth with. You will need a beam type In. lb. torque wrench or dial type. I have a nice dial type from snap on. You cannot use a click type. You will also need a dial indicator and a magnetic base. There are just some of the "special tools" among your common tools you would use like a pry bar hammer sockets etc. I thought I would just check in on the thread . Hopefully next weekend I can take care of it. My main issue will be finding someone to press the pinion bearing on. Shops aren't very helpful sometimes I have had issues in the past having a shop press a hub bearing on for me. I don't know if I mentioned this but I am doing this gear swap with the whole rear ed on the car its much easier if you take it off but this is actuially how I learned how to do it and I find it not too hard to do. It is a work out to get the carrier in an out when setting it up but once its all said and done I think I will spend less time than actually taking the rear end out and installing and bleeding the brakes etc.

 

Copper I was just wondering in the event guys don't have a press, I have used a hot plate with a 1/8 piece of sheet metal over the plate in order to heat expand a few spindle bearings to slide onto a shaft. Would this work for rear end bearings?

 

I couldn't tell ya. I would much rather pay a shop 20 bucks to install them or better yet find a buddy with a press and offer him beer.

 

Just a thought we can't press spindle bearings on if you want it to run true within .0005 Just thinking it would be better for the bearings but I guess a few thou run out ater pressing in a rear wouldn't be a big deal

 

I don't think pressing the bearings would create run out. the biggest factor in run out will be the carrier or ring gear if it has any burr's on the mounting surface. The bearings aren't tight so to speak so there is movement there they are much like wheel bearings but bigger. The bearing caps align it all and keep the spinning parts in place. Back when I was cutting ring gears and pinions we checked run out in the outer diameter so meaning the up and down but this was before we would cut the gears the gears or do a fiish cut or if we changed the plates we had them mounted on .I think since the pinion teeh mesh into the ring gears a few though In and out in variance is not a big issue. Now if you had half the teeth going deeper into the root of the gear and the other half where out then yes something would be wrong with the mounting surface of the gear. Its hard to explain with out drawing a ton of crap but if something is wrong you will see it in the marking compound which is the main objective in the install to get a good pattern.

 

I've got a press But I'm a little ways away.

 

Ok so the gear that got sent to me was an 8.5 in. gear but for an O axle so that no bueno. So all I got done today was dis assembly. I had to put the carrier back in so I could put the axles back on to park the car back under the lift. If you guys have never done it here is what I did and used to remove it all.


Take the wheel off and drum off then spin the axle to get to the bolts for the axle retainer. No c clips on these bop rear ends.



I used a thin chrome socket on the impact to get the nuts off the retaining plate. the normal impact socket was too long and too wide and I could not get it straight in. Now to remove the axles I used a big 10 lb slide hammer I use in the body shop with a "hillbilly custom" adapter to use the axle puller on it. They are different threads and I aint about to buy a different slide hammer lol. A few good pulls should get it out.





Now for the bearing caps I used an impact with a universal joint or swivel sicne the gas tank kinda gets in my way for a straight shot. Now mark bearing caps before you remove them to their side., I have punches so D is driver side and P is pass. side. To get the carrier out use a prybar underneath the center of the carrier and give a few pushes up while holding it up to avoid it falling on your head and out it should come.





Now for the front you will need a big socket for the 8.5 its 1 and 1/4 I also used my impact for this. Makes the job easy. Now to pull the yoke off I put the u joint caps back on the yoke and used a t handle deal I found and I wrapped my chain adpter from my body slide hammer kit and gave it a few good pulls and out it came. I had to beat the pinion a bit to remove it so I whacked it with a 2x4 and a 3lb sledge hammer.

 

Edit: To the resident diff specialist please feel free to let me know if you feel im doing something wrong or feel free to share any tips or tricks . Im very open to feed back as this is only my second set I have done but I thought some form of a formal write up may help guys wanting to do it on their own like I did.


Ok So I have to thank brian trick 507olds for shipping me the correct gears in return for the ones I had gotten from someone else that where not the right ones . I also have to thank 67cutlassfreak for removing the pinion bearing for me as I didn't have the right gear to do so that way I can change the shims to achive proper pinion depth for a good pattern.


after I had the bearing removed from the pinion I removed the .040 pinion shim . I only had a .015 shim but that did the trick to get a good patter. I had 507olds let me know what he thought and he said it looked good.


now to make this easy I have a pre hogged out pinion bearing so I can slip it in and out while I change shims. In my case I had one to make it work and it worked lol.


Also For back lash you don't want to use too small of a shim because it does have to be a tight fit So what I did was measured a serious of big and thin shims and measured so that I would have my thin shims on one side and a big shim on one side so I can tap that it with a ball peen hammer.


I also measured back lash on 4 points. Across the pin on the carrier and and across the open ends of the carrier. I marked what my back lash wash with a marker on each point. I also have to say check you back lash on the same part of the tooth on all 4 points. I was getting different readings until I remembered this gear has wear so I have to check on the same points every time to get a good reading. I got .010 back lash on all 4 points. I used an old carrier with my magnetic base and a dial indicator .


Now for pattern there is info out there on what to look for so I wont get into that as im sure googling it like I did will bring up what you need to use for refrence.


Now another thing that is important to keep track of everything is some dial calipers. You need to keep track of shim thickness and how much you take from one side and add to the other etc. makes it very easy .


Now I ran out of the yellow pattern compound. 507olds suggested I use lipstick for the pattern check. I asked my fiancé and she asked me why and she made me this thick paste out of lipstick and lip gloss. It was a bit thick so I thinned it out with a little trans fluid and it worked great.


Another tool you will need is an inch lb tq. wrench beam type or dial type. I have a dial type.


I don't want to get too far ahead of my self. For now I took it all back apart im going to clean the gear and press on the new bearing on the pinion with my shim that I need. OH and I almost forgot keep track of which bearing cap goes to what side. I bagged at tagged my caps bolts and shims to which ever side they belonged to.


Here is one area I check backlash on and you can see where I marked it.





here is my pattern








This is the dial in. lb. tq. wrench I have to check bearing preload.



here is my home made pattern compound. I also used a little Prussian blue and oil but I like the red better.

 

Ok so the badnews is forgot my phone at home so i couldnt take pics. But on friday 67cutlassfreak prssed on the bearing on the pinion for me with my final shim.

This morning I installed a new front pinion seal then i installed my crush sleeve and went ahead and tightened it down with the impact. The trick to not mess it up and get it in on shot with the impact is to tighten it to take the slack out then just bump the trigger on the impact and turn the pinion untill you feel a little resistance then check now you will go back and forth between bumping with the impact and checking with your in. lb wrench. I was at about 20 in lbs for pre load. I went by what my old chiltons manual said . stock stuff so im going by stock specs. I have seen guys recommend between 9 in. lbs and 22 in lbs.

Ok so after i set the pinion up. I went ahead and re torqued the ring gear again. I installed the carrier and torqued it aswell.

I checked backlash one last time and my pattern and it all looked good so i installed the axles , and all that fun stuff.

Im realy happy with the 3.08 set brian trick (507olds) hooked me up with. Going from a 2.41 to 3.08 was a major improvement on my dads tank of a car. Now it boogies. Well atleast in the shop. Still need to road test but the shopbig rig was blocking the door and we didnt feel like moving all kinds of stuff to squeeze by.

Over all i think we spent about 220 bucks on the swap no posi of course. We didnt do new bearings as everything still worked very well.

Well guys i hope this atleast helps someone get an idea of what to do.

 

nice writeup sir

 

Well I took pops car for a drive . No noises no cluncks drove like a champ. It's still not a tire roaster. I could have gone up to atleast a 3.42 but my dad is not looking to hot rod it around. The 3.08's worked great It takes off a lot faster now lol but it cruises nice the rpms are down. Overall im happy and my dad seems pleased with the off the line performance. He wanted it to cruise like his daily driver dodge Durango and it does.