Replacing differential and adding a vent hose

#1

This is a harder task then I thought it was. It took me a long-ass evening just to remove the differential. None of the bolts were rusted in hard, there’s just a lot of bolts and there’s few you can get a ratchet too.

If you are going to put in a vent hose, take a hard look at clearance around the diff vent pipe before you remove the diff. Make your decision then as to just how you are going to attach the hose.

Now that I’ve done everything the hard way, here’s what I’d do if I had to do it over again…Tap the vent pipe on top for something really small, definately smaller then 1/8NPT. Then thread in a hose barb such that you can put the hose in place from your trunk (using the hole you have to drill) after you put the diff in.

I used a hose with an inside dia. large enough to go around the vent pipe, and then used a hose clamp. The problem that creates is that there’s darn little clearance around the vent pipe when you are putting the diff back in place and a hose on the vent pipe could interfere enough that it adds an hour or two to the task.

When you are putting the diff in place, see if you can put the middle diff bolts in first. The front bolts are easier to see and that makes them easier to jockey into place last. And it’s the last bolts that are hard to get into place.

The top bolts are hard to get into place, period. At least mine were. I figure that it might have been easier if I’d a put them in first.

Get your car pretty high off of the ground. This is a task for nice big 6 ton jack stands.

Getting the diff out is a whole evening. Putting it back into place is 2 evenings.

#2

Ranger -

Did you rebuild the diff before replacing it? Sounds like a tough job unless you just replace the clutches.

Congrats an another installment of E30 education!

Steve D.

#3

Ranger wrote:

With practice comes speed. Eventually you will get it out in 30 and back in 60 minutes!

#4

Having a Gearwrench for the top bolts makes this job a lot easier!

#5

ctbimmer wrote:

[quote]Ranger wrote:

With practice comes speed. Eventually you will get it out in 30 and back in 60 minutes![/quote]

60minutes? You put that SOB entirely in place using only box-end wrenches and a socket set, with the car on jackstands in an hour, and you will not buy a beer at a NASA event for 6 months.

Re. rebuilding the diff. No. My limited slip diff turned out to have been purloined by the arch fiend Molitor. I bought a used diff. It had some residue inside of it which concerned me, but I’m going to go ahead with the install. If it starts slipping later, I’ll pull the diff, take Chuck’s rebuild kit off of my garage shelf, and rebuild it.

Re. the Gearwrench. I hit their website, but they sell a lot of stuff. What did you have in mind?

#6

Ranger wrote:

A 19mm ratcheting wrench, preferably stubby or flex head… Dealers choice.

#7

Yeah, I should of said “ratcheting wrench” as I’m not making any money from GW. I got a set last Christmas and can honestly say they’re worth every penny!

#8

[quote=Ranger]60minutes? You put that SOB entirely in place using only box-end wrenches and a socket set, with the car on jackstands in an hour, and you will not buy a beer at a NASA event for 6 months.
[/quote]
If I do it in less than 60 minutes do I get free beer at the track for life?

#9

jlevie wrote:

[quote][quote=Ranger]60minutes? You put that SOB entirely in place using only box-end wrenches and a socket set, with the car on jackstands in an hour, and you will not buy a beer at a NASA event for 6 months.
[/quote]
If I do it in less than 60 minutes do I get free beer at the track for life?[/quote]

Only if you’re swapping out my brokedick diff for your good diff.

#10

Ranger wrote:

[quote]jlevie wrote:

[quote][quote=Ranger]60minutes? You put that SOB entirely in place using only box-end wrenches and a socket set, with the car on jackstands in an hour, and you will not buy a beer at a NASA event for 6 months.
[/quote]
If I do it in less than 60 minutes do I get free beer at the track for life?[/quote]

Only if you’re swapping out my brokedick diff for your good diff.[/quote]
Where would the fun in that be? I might be inclined to beat Chuck’s time on my own diff swap for beer (I prefer Coors Banquet), but not yours.

#11

The good news is that the diff is now installed. I even went to the trouble to put low strength loktite on input and output shaft bolts. And the vent hose looks like it worked out ok.

The bad news, and this is somehow not all that surprising, is the diff has turned out to be a worn out POS that breaks at 30ftlbs.

I don’t know that I’m motivated to pull it off and rebuild it now. I may wait a spell. There’s some other things on the car that need attention and frankly, differentials aren’t as fascinating now as they were.

Jim: Of course I’m all for senseless fun, but “free beer…for life” sounded like something that I could end up regretting. Not withstanding your penchant for cheap weasel piss.

Is the spec for breakaway torque for an LSD diff written anywhere in some authoritative fashion? I didn’t see it in Bentley. I’ll need that number when I talk to the guy who sold it to me.

#12

It would be a very good idea to use some low strength thread locking compound on the 4 diff top bolts (M12, 19mm head), as these can come loose with vibration.

I HIGHLY recommend a selection of what we in the English world call ‘ratchet spanners’, what you would call a ratchet wrench. I have the bMW sizes - 8mm, 10mm, 12mm, 13mm, 14mm, 15mm, 17mm and 19mm, with flexible heads to get into every last nook and cranny. They save a lot of time and should be available from a wide variety of tool shops.

I did a similar modification to my vent hose, popped the vent out with soft hammer, threaded for 1/8NPT, and screwed in an adaptor to barb fitting for a 8mm/10mm hose (can’t remember which) mine goes through the boot floor and into a carby fuel filter (cheap $2 item), and is zip tied to rear of the RHR wheel well. No leaky, no drippy…