Hello! Log in or Register   |  Help  |  Donate  |  Buy Shirts See all banner ads | Advertise on TheSamba.com  
TheSamba.com
 
Bigger tires, changing gearing.
Page: 1, 2, 3, 4, 5, 6, 7, 8, 9  Next
Forum Index -> Vanagon Share: Facebook Twitter
Reply to topic
Print View
Quick sort: Show newest posts on top | Show oldest posts on top View previous topic :: View next topic  
Author Message
Syncronoid
Samba Member


Joined: January 21, 2012
Posts: 1110
Location: Stanford, CA and Bend, OR
Syncronoid is offline 

PostPosted: Wed Aug 15, 2018 12:07 pm    Post subject: Bigger tires, changing gearing. Reply with quote

I'm sure this has been discussed at nauseam, but hoping to keep this simple.

1990 Syncro Westy, GW2.5L, 3-knobs. I'm considering larger tires.

Currently, I'm using 215/70R16 (27.9" tall/8.5" wide) tires with 2" GW springs, Fox Shocks, stock 4:86 R&P and gearing, 930 axles and 16" rear trailing arms from Burley.

I'm fairly happy with the way the van drives with the existing gearing/tire size combination, but if I were to go with larger tires, which would you choose?.

225/70R16 (28.4" tall/8.9" wide) with 5.43 (11.7% taller) R&P

or

235/70R16 (29" tall/9.3" wide) with 5.43 (11.7% taller) R&P

or

235/70R16 (29" tall/9.3" wide) with 5.83 (20% taller) R&P
_________________
'90 Syncro Westy w/GW2.5L
Back to top
View user's profile Send private message Gallery Classifieds Feedback
E1
Samba Member


Joined: January 21, 2013
Posts: 6379
Location: Westfalia, Earth
E1 is offline 

PostPosted: Wed Aug 15, 2018 1:05 pm    Post subject: Re: Bigger tires, changing gearing. Reply with quote

We have a 5.43 with a stock 1.9 and absolutely love it.

16s with KO2s, 27.01" tall. With the power of a Subie I am not sure you need/want the extra revs, but think I would if my van to make it a climbing beast. The option of more revving is far easier on a climbing engine than not.

We swapped the .85 4th for a new .78 from Paul at Guard Transmission, a fine guy worth our circle's business. That setup mathed out to about 50-100 less revs on the highway in 4th, and a little bigger gap from 3rd to 4th now — but it's yet to show any distinct disadvantage beyond not having a 3rd to pass with as easily at the wrong speeds the once a year we actually need a quick pass.

Old gearing and stock tires, 3rd redline @ 65 mph, now @ 59 with the 27" tires, though we rarely push that hard.

Have you considered a 5-speed conversion? I'd have done that if I'd been thinking and spending just a little harder…

Arizona Transaxle HUGELY recommended also.
_________________
‘84 Westy, 2.1L with Digijet, 5.43 R+P, GT Gears
"Adding power makes you faster on the straights.
Subtracting weight makes you faster everywhere."

— Colin Chapman
Back to top
View user's profile Send private message Send e-mail Gallery Classifieds Feedback
gears
Samba Member


Joined: October 28, 2002
Posts: 4391
Location: Tamarack, Bend, Kailua
gears is offline 

PostPosted: Wed Aug 15, 2018 3:41 pm    Post subject: Re: Bigger tires, changing gearing. Reply with quote

With your present tire, you should be doing about 80mph @4,000rpm

With 29" and 5.43, you would be doing about 75 @4,000, which is pretty optimal for a 2.5

Strength-wise, I like the 5.43 7-tooth pinion more than the 5.83 6-tooth.
_________________
aka Pablo, Geary
9.36 @ 146 in '86 Hot & Sticky
'90 Syncro Westy SVX
'87 Syncro GL 2.5
https://guardtransaxle.com
Back to top
View user's profile Send private message Send e-mail Visit poster's website Gallery Classifieds Feedback
crazyvwvanman
Samba Member


Joined: January 28, 2008
Posts: 9895
Location: Orbiting San Diego
crazyvwvanman is offline 

PostPosted: Wed Aug 15, 2018 6:43 pm    Post subject: Re: Bigger tires, changing gearing. Reply with quote

According to BFG specs,

215/70R16 _ does 746 revs per mile

225/70R16 _ does 732 revs per mile, only 2% taller

235/70R16 _ does 718 revs per mile, only 4% taller

From 4.86 down to 5.43 is about 10% shorter

So switching to 5.43 would give more perceived power in all gears and higher revs at all speeds, no matter which of those tires you choose.


Mark






Syncronoid wrote:
I'm sure this has been discussed at nauseam, but hoping to keep this simple.

1990 Syncro Westy, GW2.5L, 3-knobs. I'm considering larger tires.

Currently, I'm using 215/70R16 (27.9" tall/8.5" wide) tires with 2" GW springs, Fox Shocks, stock 4:86 R&P and gearing, 930 axles and 16" rear trailing arms from Burley.

I'm fairly happy with the way the van drives with the existing gearing/tire size combination, but if I were to go with larger tires, which would you choose?.

225/70R16 (28.4" tall/8.9" wide) with 5.43 (11.7% taller) R&P

or

235/70R16 (29" tall/9.3" wide) with 5.43 (11.7% taller) R&P

or

235/70R16 (29" tall/9.3" wide) with 5.83 (20% taller) R&P
Back to top
View user's profile Send private message Gallery Classifieds Feedback
Syncronoid
Samba Member


Joined: January 21, 2012
Posts: 1110
Location: Stanford, CA and Bend, OR
Syncronoid is offline 

PostPosted: Wed Aug 15, 2018 7:02 pm    Post subject: Re: Bigger tires, changing gearing. Reply with quote

Currently, it seems closer to 75 @4,000. I usually cruise @3600-3800 on the Hwy. I'm in no hurry and like to keep the revs a little lower for longevity. Perhaps a different 4th gear??

gears wrote:
With your present tire, you should be doing about 80mph @4,000rpm

With 29" and 5.43, you would be doing about 75 @4,000, which is pretty optimal for a 2.5

Strength-wise, I like the 5.43 7-tooth pinion more than the 5.83 6-tooth.

_________________
'90 Syncro Westy w/GW2.5L


Last edited by Syncronoid on Wed Aug 15, 2018 7:17 pm; edited 2 times in total
Back to top
View user's profile Send private message Gallery Classifieds Feedback
Syncronoid
Samba Member


Joined: January 21, 2012
Posts: 1110
Location: Stanford, CA and Bend, OR
Syncronoid is offline 

PostPosted: Wed Aug 15, 2018 7:06 pm    Post subject: Re: Bigger tires, changing gearing. Reply with quote

Which is good for climbing, acceleration and offroad, but not as much for hwy, I presume.

crazyvwvanman wrote:
According to BFG specs,

215/70R16 _ does 746 revs per mile

225/70R16 _ does 732 revs per mile, only 2% taller

235/70R16 _ does 718 revs per mile, only 4% taller

From 4.86 down to 5.43 is about 10% shorter

So switching to 5.43 would give more perceived power in all gears and higher revs at all speeds, no matter which of those tires you choose.


Mark






Syncronoid wrote:
I'm sure this has been discussed at nauseam, but hoping to keep this simple.

1990 Syncro Westy, GW2.5L, 3-knobs. I'm considering larger tires.

Currently, I'm using 215/70R16 (27.9" tall/8.5" wide) tires with 2" GW springs, Fox Shocks, stock 4:86 R&P and gearing, 930 axles and 16" rear trailing arms from Burley.

I'm fairly happy with the way the van drives with the existing gearing/tire size combination, but if I were to go with larger tires, which would you choose?.

225/70R16 (28.4" tall/8.9" wide) with 5.43 (11.7% taller) R&P

or

235/70R16 (29" tall/9.3" wide) with 5.43 (11.7% taller) R&P

or

235/70R16 (29" tall/9.3" wide) with 5.83 (20% taller) R&P

_________________
'90 Syncro Westy w/GW2.5L
Back to top
View user's profile Send private message Gallery Classifieds Feedback
E1
Samba Member


Joined: January 21, 2013
Posts: 6379
Location: Westfalia, Earth
E1 is offline 

PostPosted: Wed Aug 15, 2018 7:31 pm    Post subject: Re: Bigger tires, changing gearing. Reply with quote

What highway speed do you like?
_________________
‘84 Westy, 2.1L with Digijet, 5.43 R+P, GT Gears
"Adding power makes you faster on the straights.
Subtracting weight makes you faster everywhere."

— Colin Chapman
Back to top
View user's profile Send private message Send e-mail Gallery Classifieds Feedback
Syncronoid
Samba Member


Joined: January 21, 2012
Posts: 1110
Location: Stanford, CA and Bend, OR
Syncronoid is offline 

PostPosted: Wed Aug 15, 2018 7:45 pm    Post subject: Re: Bigger tires, changing gearing. Reply with quote

3750 RPM. Laughing

70-75 is fine. Would settle for 70 if it meant getting the tire size I want.

E1 wrote:
What highway speed do you like?

_________________
'90 Syncro Westy w/GW2.5L
Back to top
View user's profile Send private message Gallery Classifieds Feedback
E1
Samba Member


Joined: January 21, 2013
Posts: 6379
Location: Westfalia, Earth
E1 is offline 

PostPosted: Wed Aug 15, 2018 7:49 pm    Post subject: Re: Bigger tires, changing gearing. Reply with quote

Do you like your current first gear on rough dirt climbs?
_________________
‘84 Westy, 2.1L with Digijet, 5.43 R+P, GT Gears
"Adding power makes you faster on the straights.
Subtracting weight makes you faster everywhere."

— Colin Chapman
Back to top
View user's profile Send private message Send e-mail Gallery Classifieds Feedback
Syncronoid
Samba Member


Joined: January 21, 2012
Posts: 1110
Location: Stanford, CA and Bend, OR
Syncronoid is offline 

PostPosted: Wed Aug 15, 2018 7:56 pm    Post subject: Re: Bigger tires, changing gearing. Reply with quote

Yes, though I have the Syncro low gear as well.

E1 wrote:
Do you like your current first gear on rough dirt climbs?

_________________
'90 Syncro Westy w/GW2.5L
Back to top
View user's profile Send private message Gallery Classifieds Feedback
crazyvwvanman
Samba Member


Joined: January 28, 2008
Posts: 9895
Location: Orbiting San Diego
crazyvwvanman is offline 

PostPosted: Wed Aug 15, 2018 8:25 pm    Post subject: Re: Bigger tires, changing gearing. Reply with quote

With your current 746 rev per mile tires and stock tranny gearing......

75 mph = 1.25 miles per minute

746 x 1.25 = 933 tire revs per minute

933 x 4.86 = 4534 pinion shaft revs per minute

4534 x .85 (4th gear) = 3854 mainshaft revs per minute

mainshaft turns at engine speed, so....

----75 mph = 3850 with your current setup, approx------
----73 mph = 3750 with your current setup, approx------
----70 mph = 3600 with your current setup, approx------


now change to 235/70R16 and 5.43

75 mph would be 4150 rpm, approx
70 mph would be 3865 rpm, approx
68 mph would be 3750 rpm, approx


So the fairly big change to 5.43 can't be compensated for even with the larger of your tire options.
Jumping past that to 5.83 would seem out of the question for you.

Mark
Back to top
View user's profile Send private message Gallery Classifieds Feedback
Syncronoid
Samba Member


Joined: January 21, 2012
Posts: 1110
Location: Stanford, CA and Bend, OR
Syncronoid is offline 

PostPosted: Wed Aug 15, 2018 8:43 pm    Post subject: Re: Bigger tires, changing gearing. Reply with quote

So, essentially, if I want the bigger tires and all around comparable driveability, I will need to slow down on the hwy. The rest should be ok, no?

crazyvwvanman wrote:
With your current 746 rev per mile tires and stock tranny gearing......

75 mph = 1.25 miles per minute

746 x 1.25 = 933 tire revs per minute

933 x 4.86 = 4534 pinion shaft revs per minute

4534 x .85 (4th gear) = 3854 mainshaft revs per minute

mainshaft turns at engine speed, so....

----75 mph = 3850 with your current setup, approx------
----73 mph = 3750 with your current setup, approx------
----70 mph = 3600 with your current setup, approx------


now change to 235/70R16 and 5.43

75 mph would be 4150 rpm, approx
70 mph would be 3865 rpm, approx
68 mph would be 3750 rpm, approx


So the fairly big change to 5.43 can't be compensated for even with the larger of your tire options.
Jumping past that to 5.83 would seem out of the question for you.

Mark

_________________
'90 Syncro Westy w/GW2.5L
Back to top
View user's profile Send private message Gallery Classifieds Feedback
gears
Samba Member


Joined: October 28, 2002
Posts: 4391
Location: Tamarack, Bend, Kailua
gears is offline 

PostPosted: Wed Aug 15, 2018 9:23 pm    Post subject: Re: Bigger tires, changing gearing. Reply with quote

Syncronoid wrote:
Perhaps a different 4th gear??


The choices are almost unlimited:
Image may have been reduced in size. Click image to view fullscreen.

_________________
aka Pablo, Geary
9.36 @ 146 in '86 Hot & Sticky
'90 Syncro Westy SVX
'87 Syncro GL 2.5
https://guardtransaxle.com
Back to top
View user's profile Send private message Send e-mail Visit poster's website Gallery Classifieds Feedback
Syncronoid
Samba Member


Joined: January 21, 2012
Posts: 1110
Location: Stanford, CA and Bend, OR
Syncronoid is offline 

PostPosted: Wed Aug 15, 2018 9:35 pm    Post subject: Re: Bigger tires, changing gearing. Reply with quote

Oh dear, so many choices. Something that keeps RPM's down a bit at Hwy speeds, but isn't too much of a jump from 3rd to where I have to shift down from 4th on modest hills.

I'm at my house in Bend the last week of August, perhaps a sit down and a couple of crowlers to discuss! Smile

gears wrote:
Syncronoid wrote:
Perhaps a different 4th gear??


The choices are almost unlimited:
Image may have been reduced in size. Click image to view fullscreen.

_________________
'90 Syncro Westy w/GW2.5L
Back to top
View user's profile Send private message Gallery Classifieds Feedback
gears
Samba Member


Joined: October 28, 2002
Posts: 4391
Location: Tamarack, Bend, Kailua
gears is offline 

PostPosted: Wed Aug 15, 2018 10:01 pm    Post subject: Re: Bigger tires, changing gearing. Reply with quote

This is a pretty good graph website:

http://gearwars.net/
_________________
aka Pablo, Geary
9.36 @ 146 in '86 Hot & Sticky
'90 Syncro Westy SVX
'87 Syncro GL 2.5
https://guardtransaxle.com
Back to top
View user's profile Send private message Send e-mail Visit poster's website Gallery Classifieds Feedback
Pcforno
Samba Member


Joined: October 14, 2014
Posts: 575
Location: Santa Fe, nm
Pcforno is offline 

PostPosted: Thu Aug 16, 2018 6:11 am    Post subject: Re: Bigger tires, changing gearing. Reply with quote

I have a Syncro westy, 1.8t with about 265ft lbs torque.
I have a 4.86 R and P, normal 4th heat (IIRC .77).
I have run stock tires, 215/70 R 16, and most currently 235/70 R16
I’m loving the 236/70 R16
Highway RPM (70-75 mph) is about 3500. My MPG increased by 1-2 and I don’t notice any effect on crawling speed.
Plenty of power, no real change in when I shift.
Your Subaru engine should be fine as your torque curve is much flatter than mine due to turbo lag
Back to top
View user's profile Send private message Gallery Classifieds Feedback
davevickery
Samba Member


Joined: July 16, 2005
Posts: 2887
Location: Fort Collins, CO
davevickery is offline 

PostPosted: Thu Aug 16, 2018 7:22 am    Post subject: Re: Bigger tires, changing gearing. Reply with quote

Huge difference between GW 2.5 and chipped 1.8T. I like the idea of 225/70-16 and 5.43. I would compare stock tires and gearing to your change and it that puts you back close to stock. But it's a lot of money considering you can just keep it like it is.
Back to top
View user's profile Send private message Gallery Classifieds Feedback
Pcforno
Samba Member


Joined: October 14, 2014
Posts: 575
Location: Santa Fe, nm
Pcforno is offline 

PostPosted: Thu Aug 16, 2018 8:11 am    Post subject: Re: Bigger tires, changing gearing. Reply with quote

True Dave - although might be interesting to compare torque curves. If the 2.5 GW Is like the EJ25 then He may have more torque low down. Still if I agree I’d i had to change R and P I’d just keep it where it’s at...
Back to top
View user's profile Send private message Gallery Classifieds Feedback
gears
Samba Member


Joined: October 28, 2002
Posts: 4391
Location: Tamarack, Bend, Kailua
gears is offline 

PostPosted: Thu Aug 16, 2018 9:09 am    Post subject: Re: Bigger tires, changing gearing. Reply with quote

.
This is a graph I did for someone going from stock tire size to 29", retaining a waterboxer engine (2.2). It shows a potential 3rd & 4th gear change.
Image may have been reduced in size. Click image to view fullscreen.


This is a graph showing 5.43 R&P installed with 29" tires, stock gearing:
Image may have been reduced in size. Click image to view fullscreen.


I've contemplated changing from 4.86 to 5.43 in my own SVX Syncro with 27" tires, more to get a lower G gear than for any other reason. (I now have a selection of mainshafts suitable for any combo.) The only thing holding me back is that I like the 4.86 more than any other R&P, strength-wise. 5.43 is certainly OK, though ..
_________________
aka Pablo, Geary
9.36 @ 146 in '86 Hot & Sticky
'90 Syncro Westy SVX
'87 Syncro GL 2.5
https://guardtransaxle.com
Back to top
View user's profile Send private message Send e-mail Visit poster's website Gallery Classifieds Feedback
Waldi
Samba Member


Joined: February 28, 2014
Posts: 1752
Location: Germany
Waldi is offline 

PostPosted: Thu Aug 16, 2018 10:38 am    Post subject: Re: Bigger tires, changing gearing. Reply with quote

Orinal Syncro 16 with 112hp DJ has a 5,83x0,85 box.
You should stay close to that.
5,43x0,85 is good.
But i would take 205/80-16 or 6,50x16 if you realy want to go for taler tires and not for the look.
Back to top
View user's profile Send private message Gallery Classifieds Feedback
Display posts from previous:   
Reply to topic    Forum Index -> Vanagon All times are Mountain Standard Time/Pacific Daylight Savings Time
Page: 1, 2, 3, 4, 5, 6, 7, 8, 9  Next
Page 1 of 9

 
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum

About | Help! | Advertise | Donate | Premium Membership | Privacy/Terms of Use | Contact Us | Site Map
Copyright © 1996-2023, Everett Barnes. All Rights Reserved.
Not affiliated with or sponsored by Volkswagen of America | Forum powered by phpBB
Links to eBay or other vendor sites may be affiliate links where the site receives compensation.