Forester R160 1-bolt vs 5-bolt difference?

[davidaga]

Noob question coming up.
Other than the number of bolts, what other differences does the 1-bolt and 5-bolt R160 rear diffs have?

I have a 2011 Forester non-turbo JDM and looking at the diff I can see 1-bolt. I love off-roading so I was wondering is there any gain in replacing the 1-bolt with a 5-bolt diff? I am planning to install a Torq locker for off-roading.

 

[Kevin]

G'day & Welcome over here too! I'm sure someone will be along shortly to answer your question

 

[El_Freddo]

From what I understand the one bolt r160 refers to the single bolt used to hold the bearing tensioner in place - same design as the front diff in the gearbox.

The five bolt unit uses shims tiger the correct bearing backlash/preload etc - I can’t remember which one is the correct term for what these shims adjust.

Otherwise they’re essentially the same unit and will swap into any model with the R160. The diff centres can be moved between housings to sort out the change in stub axles or not, or to swap an LSD into an open diff and retain the original ratio for the recipient vehicle. Some diff housing shaving maybe needed at times, just depends on what’s needed in the given situation.

Only thing to double check is the oil seals are the same between the one and five bolt diffs. My bet is they’re the same but if there’s a change it could be in that area.

I tried a parts search but could only find the five bolt setup - tried 2016 XV and a 2018 Forester. That’s not to say that the diagrams 100% correct.

Looking at the torque locker website they show the difference in the one and five bolt diffs. They’re a little more different than I thought with a change in the front mount. There’s a bolt number change and possibly a change of location of the two front mount bolt location on the one bolt diff. You’ll see, scroll down near the bottom

TORQ Locker for Subaru R160 5-Bolt open differentials – Torq-Masters

www.torqmasters.com

Cheers

Bennie

 

[El_Freddo]

Had a deeper look on the torq locker website and the models I chose to look at were all five bolt from factory.

I’ve just checked out the tribeca diff (edit: also cross referenced with 2018 CVT outback, checks out same for one bolt) and this is what I found:

One bolt diff oil seal: 32x50x9
Five bolt diff oil seal: 32x52x11

This suggests that there is most likely a difference in the drive shaft diametre on the input shaft to the diff. That would also explain why torque locker requires the specification as to whether you have the one or five bolt.

My advice is to proceed with caution with using a five bolt. Find a second one bolt diff with the same ratio that’s also an open diff and swap the locker into.

Cheers

Bennie

 

[jf1sf5]

You are correct El Freddo. But the housings are different too, the one bolt beeing smaller and thus the ring and pinion too. Better find a 5 bolt if you want to go off roading rather than soft roading.

 

[El_Freddo]

@jf1sf5 - I noted the front mount difference but didn’t know about the overall housing difference.

Hopefully for @davidaga 2 of the 4 front mounts on the 5 bolt diff line up with the two bolt mount setup on the 1 bolt diff. It could be a bush difference, I don’t know as I haven’t played with these - any small difference quickly turns into a huge headache when it comes time to swap.

Again, research is needed into the difference in the rear shaft where it plugs into the rear diff - 1 bolt vs 5 bolt.

Cheers

Bennie

 

[jf1sf5]

My SF had a 5 bolt I changed for a 1 bolt (with its own cv's) because it had a viscous LSD. As it wasn't very efficient I decided to install a Quaife helical but they can only be fitted in a 5 bolt. So I compared both 1 bolt and 5 bolt r160 and in fact they are quite different, for example the inner cv's are not compatible nor are the internals (ring and pinion) but the shaft is just a bolt on thing. The only advantage with the 1 bolt, in my opinion, is you gain about 1,5 cm ground clearance thanks to the overall height of he housing !

 

[El_Freddo]

@jf1sf5 - awesome info above! Thanks for sharing.

Cheers

Bennie

 

[davidaga]

Thank you for sharing your insights. I may try to source a R160 5-bolt to install the Torq Locker and keep the 1-bolt stock.

 

[scalman]

you cant just change rear diffs as you please it must be same ratio with gearbox . and torque making lockers for both diff styles 5 and 1 bolts.

 

[jf1sf5]

Scalman is right, don't forget to look for the same diff ratio (mine are 4,11:1)

 

[El_Freddo]

you cant just change rear diffs as you please it must be same ratio with gearbox . and torque making lockers for both diff styles 5 and 1 bolts.

Good point to mention Scalman! This could be a disappointing oversight if the wrong ratio was used!

Cheers

Bennie