Subaru Outback Forums banner

1 - 19 of 19 Posts

·
Registered
Joined
·
27 Posts
Discussion Starter #1
Anyone installed one of these on a 5th Gen? I did a search and I couldn't find any posts about it.

If you have, how do you like it? What noticeable changes, if any, did you pick up on?
 

·
Registered
18 Outback 3.6r Touring
Joined
·
489 Posts
If that’s all your doing, save your money. It takes mores then a lightweight pulley to notice any improvement. And usually that will be after you’ve done MANY other mods to see any effect. Or is it affect?
 

·
Registered
Joined
·
27 Posts
Discussion Starter #3
If that’s all your doing, save your money. It takes mores then a lightweight pulley to notice any improvement. And usually that will be after you’ve done MANY other mods to see any effect. Or is it affect?
Im planning to get some Method Racing 503's also. They're 8lbs lighter than the factory wheels. I'm trying to reduce unsprung weight and rotational mass. I figure anything that reduces how hard the engine and drivetrain have to work is a plus. I'm not trying to turn an outback into a wrx, I just want to reduce weight to cut down on wear and tear.
 

·
Registered
Joined
·
27 Posts
Discussion Starter #5
Your best bang for the buck would be to reduce your own weight first, ( and I'm not saying that to be insulting - we all have a few pounds to lose, I could shed 20 or 30)
Ok. Thanks for the advice...
 

·
Registered
2018 3.6R Limited
Joined
·
121 Posts
Your best bang for the buck would be to reduce your own weight first, ( and I'm not saying that to be insulting - we all have a few pounds to lose, I could shed 20 or 30)
LOL! I resemble that remark.
Makes sense though.
 

·
Registered
2010 2.5 CVT Premium
Joined
·
1,007 Posts
Your best bang for the buck would be to reduce your own weight first, ( and I'm not saying that to be insulting - we all have a few pounds to lose, I could shed 20 or 30)
Not necessarily.
Rotating mass of the tires and wheels is roughly a 3:1 ratio vs weight reduction of fixed mass for accelerating the vehicle.
So dropping 8# per corner is equivalent to dropping almost 100# out of the car. I remember a rule-of-thumb that 150# (?) is about a 0.1 second acceleration change.
Be careful about adding tire weight after going to lightweight rims though. Added tire mass at the outer diameter is more inertia to spin up than mass at the wheel.

And losing weight from oneself is almost always a good idea.
 

·
Registered
2019 Limited 2.5
Joined
·
216 Posts
Not necessarily.
Rotating mass of the tires and wheels is roughly a 3:1 ratio vs weight reduction of fixed mass for accelerating the vehicle.
So dropping 8# per corner is equivalent to dropping almost 100# out of the car. I remember a rule-of-thumb that 150# (?) is about a 0.1 second acceleration change.
Be careful about adding tire weight after going to lightweight rims though. Added tire mass at the outer diameter is more inertia to spin up than mass at the wheel.

And losing weight from oneself is almost always a good idea.
I assume you are talking about a 3:1 ratio of impact of rotating mass versus static sprung mass on straight line acceleration. Getting fancy are we? Well you could also leave your wife behind and save another 100 lbs.
 

·
Registered
Joined
·
27 Posts
Discussion Starter #10
its an outback not a wrx. save your coin
I know it's not a wrx. I'm not trying to 'make it faster'. I just want to get some Geolandar G015's aaannd Im trying to offset the increased weight so the car drives the same after I put the heavier new tires on. Is that a thing that works? Or am I wasting my time?
 

·
Premium Member
Joined
·
41 Posts
I just bought one for my 98 LOB. Because the stock oem one is starting to ware out, and cut into my timing cover a bit. So instead of going oe subaru i decided to get an aftermarket one to just reduce the rotating mass and because it was cheaper that oe.
 

·
Registered
18 Outback 3.6r Touring
Joined
·
489 Posts
I know it's not a wrx. I'm not trying to 'make it faster'. I just want to get some Geolandar G015's aaannd Im trying to offset the increased weight so the car drives the same after I put the heavier new tires on. Is that a thing that works? Or am I wasting my time?
The latter, wasting your time. I got the G015s two years ago on a set of stock 17” wheels. Also, upsized to 235/65-17. Besides handling and ride I haven’t noticed any difference. My opinion, you should just get your MR502s throw the G015s on it and see you like it before doing anything else. Then check back and let us know.
 

·
Registered
Joined
·
27 Posts
Discussion Starter #13
Not necessarily.
Rotating mass of the tires and wheels is roughly a 3:1 ratio vs weight reduction of fixed mass for accelerating the vehicle.
So dropping 8# per corner is equivalent to dropping almost 100# out of the car. I remember a rule-of-thumb that 150# (?) is about a 0.1 second acceleration change.
Be careful about adding tire weight after going to lightweight rims though. Added tire mass at the outer diameter is more inertia to spin up than mass at the wheel.

And losing weight from oneself is almost always a good idea.
So, let's say I got the heavier tires and lighter wheels, so basically losing 2#s per corner. By my math, that's an overall improvement, but it sounds like you're saying that this would make it worse? Please explain?
 

·
Registered
2010 2.5 CVT Premium
Joined
·
1,007 Posts
It starts getting more complex.
The tire and wheel are not uniform in density. If you have two tire/wheel setups with the same combined weight, setup A with a lighter wheel and heavier tire has more rotational inertia than setup B with the heavier wheel and lighter tire. The further out from the center of rotation the mass is, the greater the rotational inertia.
An application of this is the figure skater on ice that starts a spin with arms out and speeds up the spin by pulling arms in. The total mass has not changed but where the mass is located with respect to the center of rotation has changed and the rotational inertia has changed.

In your specific case, the change with a net 2# loss would have to be measured or calculated to know if it is an improvement or not.
But in the big picture, these are small effects that you are likely not to notice or be able to measure. Everyday driving does not wring out the max potential of any car so small changes on this scale are in the noise.
 

·
Registered
Joined
·
27 Posts
Discussion Starter #15
It starts getting more complex.
The tire and wheel are not uniform in density. If you have two tire/wheel setups with the same combined weight, setup A with a lighter wheel and heavier tire has more rotational inertia than setup B with the heavier wheel and lighter tire. The further out from the center of rotation the mass is, the greater the rotational inertia.
An application of this is the figure skater on ice that starts a spin with arms out and speeds up the spin by pulling arms in. The total mass has not changed but where the mass is located with respect to the center of rotation has changed and the rotational inertia has changed.

In your specific case, the change with a net 2# loss would have to be measured or calculated to know if it is an improvement or not.
But in the big picture, these are small effects that you are likely not to notice or be able to measure. Everyday driving does not wring out the max potential of any car so small changes on this scale are in the noise.
I appreciate the explanation. That makes a lot of sense. I wish I knew how to do the math on this myself, but I guess I'll just have to do whatever feels right. I would like to eventually replace the factory wheels, just because I want to. I guess the pulley replacement isn't getting a lot of support. I was hoping to talk to someone who's done it and get their thoughts, but I guess no one has.
Thanks again.
 

·
Registered
18 Outback 3.6r Touring
Joined
·
489 Posts
I was hoping to talk to someone who's done it and get their thoughts, but I guess no one has.
Ask on the WRX forums. You’ll find lots of support. But like I previously said, it’s one of the last thing you do after turbos, injectors, pumps, clutch and especially light weight fly wheel.
 

·
Registered
05 Xt beatin' to an inch of its life
Joined
·
567 Posts
I’ll help. I’ve installed two on two different 05’s. The Perrin one your talking about. I have noticed an immediate difference. Anyone who says otherwise has not driven many of these models back-to-back with and without it installed. If I were to do any if them again, I would recommend it. Especially if you’re replacing a failing one, go with this one.
 

·
Registered
05 Xt beatin' to an inch of its life
Joined
·
567 Posts
Also, beware that if you do a lightened flywheel (manual box) also, you can run into crankshaft position sensor problems.
 

·
Registered
Joined
·
27 Posts
Discussion Starter #19
I’ll help. I’ve installed two on two different 05’s. The Perrin one your talking about. I have noticed an immediate difference. Anyone who says otherwise has not driven many of these models back-to-back with and without it installed. If I were to do any if them again, I would recommend it. Especially if you’re replacing a failing one, go with this one.
Thank you. I might seriously consider it now.
 
1 - 19 of 19 Posts
Top