Checking if rear diff install went smoothly

Chopperpilot · 09-18-2023, 08:16 PM

I thought I'd ask here as there's a lot more 'how to' knowledge floating around here than on most Subaru forums. I installed a Quaife ATB differential into a 98 outback 4.44 housing, I then installed that housing into my 2023 crosstrek 6MT. I did the gear pattern check and it was good, I put new carrier bearings in. I did not touch the pinion setup. The pinion preload seemed to be at the lower end of the range (not surprising with a used differential unknown miles, but good condition). Backlash was good as well. Installed it with Amsoil 75w-90.

So far I've put about 200-300miles on it and no leaks or noises. When driving I hear the tires most of all and a little engine noise when giving it throttle. I've checked it with an IR temp gun after an hour long drive and it was only about 95* on the aluminum rear cover (this is in Alaska in September, so ambient temp was only 50* or so) . No noticeable increase in drive train slop. So everything seems hunky dory, but this is my first differential swap/setup I've done myself. It didn't really require any 'setup' I put it back together with the spacers that were in it, checked backlash and tooth pattern after torquing the side plates down.

I have a long cross country trip coming up (Alaska to NJ) and wanted to see if anybody out there had any experience with swapping a diff out and how soon the first signs that you didn't do something quite right show up? I still have the factory differential assembly that I can reinstall at any time relatively easily (it's just drained, I'll probably take it with me on my trip). Any experience on what to look/listen for? or check before a long trip like this?

* Registered users of the site do not see these ads.

K3rm1tth3fr0g · 09-18-2023, 08:39 PM

Quote:

Originally Posted by Chopperpilot

I thought I'd ask here as there's a lot more 'how to' knowledge floating around here than on most Subaru forums. I installed a Quaife ATB differential into a 98 outback 4.44 housing, I then installed that housing into my 2023 crosstrek 6MT. I did the gear pattern check and it was good, I put new carrier bearings in. I did not touch the pinion setup. The pinion preload seemed to be at the lower end of the range (not surprising with a used differential unknown miles, but good condition). Backlash was good as well. Installed it with Amsoil 75w-90.

So far I've put about 200-300miles on it and no leaks or noises. When driving I hear the tires most of all and a little engine noise when giving it throttle. I've checked it with an IR temp gun after an hour long drive and it was only about 95* on the aluminum rear cover (this is in Alaska in September, so ambient temp was only 50* or so) . No noticeable increase in drive train slop. So everything seems hunky dory, but this is my first differential swap/setup I've done myself. It didn't really require any 'setup' I put it back together with the spacers that were in it, checked backlash and tooth pattern after torquing the side plates down.

I have a long cross country trip coming up (Alaska to NJ) and wanted to see if anybody out there had any experience with swapping a diff out and how soon the first signs that you didn't do something quite right show up? I still have the factory differential assembly that I can reinstall at any time relatively easily (it's just drained, I'll probably take it with me on my trip). Any experience on what to look/listen for? or check before a long trip like this?

Just know that if you're using a thermal camera on aluminum you need to put tape or another surface in order to avoid reflective distortion of the reading

Chopperpilot · 09-19-2023, 01:04 AM

I read up on that, it seems it's an issue for 'shiny' metals. I cleaned the gunk of the factory aluminum cover, but I don't think it would classify as shiny. But next time I'm out in it, I'll run the thermometer over a few different spots on it.

arse_sidewards · 09-19-2023, 06:51 AM

If it's not getting hot in the first few hundred miles it is almost certainly fine.

Chopperpilot · 09-21-2023, 12:33 AM

Thanks, I towed a trailer with it today (maybe 1K lbs total) helping the girlfriend get a woodstove. I checked with the IR temp gun and it was about 112*, 120* at the cv axle seal area (this coincides with transfer cases I've checked as well, hotter at the seal). Still no noise, so I can probably relax and stop wondering about it.

K3rm1tth3fr0g · 09-21-2023, 01:20 AM

Quote:

Originally Posted by Chopperpilot

Thanks, I towed a trailer with it today (maybe 1K lbs total) helping the girlfriend get a woodstove. I checked with the IR temp gun and it was about 112*, 120* at the cv axle seal area (this coincides with transfer cases I've checked as well, hotter at the seal). Still no noise, so I can probably relax and stop wondering about it.

My guess is it's fine

Jedi03 · 09-21-2023, 01:55 PM

normally if its not setup correctly it will make alot of noise or fail within the miles you have on it already...if it tracked well and as you had described it, i would call it good too!

Chopperpilot · 09-27-2023, 02:47 PM

Thanks guys! I appreciate the responses. I 'tried' out the differential (before and after) on crossed up wheel ramps, the difference was pretty amazing. Stock it wouldn't back up the crossed up ramps (1 frt wheel/1 rear wheel) at all, with the Quaife, it spun for a sec, then backed up lifting a rear wheel off the ground. Just like I heard, with the modern traction control on these cars, it really makes the helical gear LSDs perform nicely.
I drove from Kansas to Alaska pulling a trailer with my truck with a recently rebuilt turbo, so I'm getting more relaxed about it being good to go. I figured like the turbo, if you don't set a rear end up correct, it'll let you know pretty soon.

09-18-2023, 08:16 PM	#1
Chopperpilot Scooby Newbie Member#: 531699 Join Date: Oct 2022 Location: Fairbanks, Alaska Vehicle: 2023 Crosstrek	Checking if rear diff install went smoothly I thought I'd ask here as there's a lot more 'how to' knowledge floating around here than on most Subaru forums. I installed a Quaife ATB differential into a 98 outback 4.44 housing, I then installed that housing into my 2023 crosstrek 6MT. I did the gear pattern check and it was good, I put new carrier bearings in. I did not touch the pinion setup. The pinion preload seemed to be at the lower end of the range (not surprising with a used differential unknown miles, but good condition). Backlash was good as well. Installed it with Amsoil 75w-90. So far I've put about 200-300miles on it and no leaks or noises. When driving I hear the tires most of all and a little engine noise when giving it throttle. I've checked it with an IR temp gun after an hour long drive and it was only about 95* on the aluminum rear cover (this is in Alaska in September, so ambient temp was only 50* or so) . No noticeable increase in drive train slop. So everything seems hunky dory, but this is my first differential swap/setup I've done myself. It didn't really require any 'setup' I put it back together with the spacers that were in it, checked backlash and tooth pattern after torquing the side plates down. I have a long cross country trip coming up (Alaska to NJ) and wanted to see if anybody out there had any experience with swapping a diff out and how soon the first signs that you didn't do something quite right show up? I still have the factory differential assembly that I can reinstall at any time relatively easily (it's just drained, I'll probably take it with me on my trip). Any experience on what to look/listen for? or check before a long trip like this? * Registered users of the site do not see these ads.

09-19-2023, 01:04 AM	#3
Chopperpilot Scooby Newbie Member#: 531699 Join Date: Oct 2022 Location: Fairbanks, Alaska Vehicle: 2023 Crosstrek	I read up on that, it seems it's an issue for 'shiny' metals. I cleaned the gunk of the factory aluminum cover, but I don't think it would classify as shiny. But next time I'm out in it, I'll run the thermometer over a few different spots on it. Last edited by Chopperpilot; 09-19-2023 at 01:10 AM. Reason: looked up thermal distortion

Thread Tools
Show Printable Version Email this Page
Display Modes
Linear Mode Switch to Hybrid Mode Switch to Threaded Mode

09-19-2023, 06:51 AM	#4
arse_sidewards Scooby Newbie Member#: 532328 Join Date: Dec 2022	If it's not getting hot in the first few hundred miles it is almost certainly fine.

09-21-2023, 12:33 AM	#5
Chopperpilot Scooby Newbie Member#: 531699 Join Date: Oct 2022 Location: Fairbanks, Alaska Vehicle: 2023 Crosstrek	Thanks, I towed a trailer with it today (maybe 1K lbs total) helping the girlfriend get a woodstove. I checked with the IR temp gun and it was about 112, 120 at the cv axle seal area (this coincides with transfer cases I've checked as well, hotter at the seal). Still no noise, so I can probably relax and stop wondering about it.

09-21-2023, 01:55 PM	#7
Jedi03 Scooby Specialist Member#: 491095 Join Date: Sep 2018 Chapter/Region: SWIC Location: New Mexico Vehicle: 2009 STi Blue Blue	normally if its not setup correctly it will make alot of noise or fail within the miles you have on it already...if it tracked well and as you had described it, i would call it good too!

09-27-2023, 02:47 PM	#8
Chopperpilot Scooby Newbie Member#: 531699 Join Date: Oct 2022 Location: Fairbanks, Alaska Vehicle: 2023 Crosstrek	Thanks guys! I appreciate the responses. I 'tried' out the differential (before and after) on crossed up wheel ramps, the difference was pretty amazing. Stock it wouldn't back up the crossed up ramps (1 frt wheel/1 rear wheel) at all, with the Quaife, it spun for a sec, then backed up lifting a rear wheel off the ground. Just like I heard, with the modern traction control on these cars, it really makes the helical gear LSDs perform nicely. I drove from Kansas to Alaska pulling a trailer with my truck with a recently rebuilt turbo, so I'm getting more relaxed about it being good to go. I figured like the turbo, if you don't set a rear end up correct, it'll let you know pretty soon.