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crazyvwvanman Samba Member
Joined: January 28, 2008 Posts: 9918 Location: Orbiting San Diego
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Posted: Tue Mar 24, 2015 10:30 am Post subject: |
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I have 215/65R16 in the spare well of a couple of my 2wd vans. For Syncros I would like to use 215/70R16 but only if I can make the spare fit where it belongs. I have been carrying 215/75R15 in there in my Syncros for 20 years and it is a very tight squeeze. I don't mind a little cutting and welding in non-vital locations if that will get 215/70R16 in there.
Mark |
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Waldi Samba Member
Joined: February 28, 2014 Posts: 1752 Location: Germany
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Posted: Tue Mar 24, 2015 12:59 pm Post subject: |
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rsxsr wrote: |
In theory to fit 4 more teeth to the ring gear since the diameter remains the same, the teeth would need to be physically smaller in dimension to fit 38 teeth. |
With this theorie, the 6,16 should be the best. Which it ist not.
The 6 teeth on the pinion are bigger than the 7.
It is not the quantity of steel that makes it stronger, it is the time and torque per teeth. |
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MarkWard Samba Member
Joined: February 09, 2005 Posts: 17109 Location: Retired South Florida
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Posted: Tue Mar 24, 2015 1:39 pm Post subject: |
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The pinion crown would have more teeth sharing the load with a higher number. In other words, more teeth meshed at one time as it turns the ring gear. I get what you are saying though. _________________ ☮️ |
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clift_d Samba Member
Joined: December 02, 2012 Posts: 265 Location: Hackney innit, UK
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Posted: Wed Mar 25, 2015 2:51 am Post subject: |
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crazyvwvanman wrote: |
I have 215/65R16 in the spare well of a couple of my 2wd vans. For Syncros I would like to use 215/70R16 but only if I can make the spare fit where it belongs. I have been carrying 215/75R15 in there in my Syncros for 20 years and it is a very tight squeeze. I don't mind a little cutting and welding in non-vital locations if that will get 215/70R16 in there.
Mark |
According to the manufacturer's info, the BFG ATs that we have fitted in 215/70 R16 are only 0.2" bigger than the 215/75 R15 size in the same tyre, so I shouldn't have thought you'll find much issue with them if the R15 size already fits. _________________ 1988 LHD T25 1.6TD Westfalia Club Joker syncro |
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crazyvwvanman Samba Member
Joined: January 28, 2008 Posts: 9918 Location: Orbiting San Diego
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Posted: Wed Mar 25, 2015 9:40 am Post subject: |
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That info shows the tire to be slightly larger in all dimensions, not just diameter. As I said the 215/75R15 is a very tight squeeze so larger in all dimensions isn't going to fit the same in the front spare well. In any case I see that BFG is going to be making the new T/A KO2 in a strong 215/65R16 size soon so that should solve my spare well issues.
http://www.tirerack.com/tires/tires.jsp?tireMake=B...p;i1_Qty=5
Mark
clift_d wrote: |
According to the manufacturer's info, the BFG ATs that we have fitted in 215/70 R16 are only 0.2" bigger than the 215/75 R15 size in the same tyre, so I shouldn't have thought you'll find much issue with them if the R15 size already fits. |
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Jon_slider Samba Member
Joined: April 11, 2007 Posts: 5091 Location: Santa Cruz, Crowdifornia
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Posted: Wed Mar 25, 2015 10:34 am Post subject: |
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crazyvwvanman wrote: |
I see that BFG is going to be making the new T/A KO2 in a strong 215/65R16 size soon |
excellent!
Maybe you could share a pic of how you modify your clamshell to fit your spare.
The 215x65x16 is a 27" D rated tire, 6% taller than stock, is 2 pounds heavier (stronger construction) than the C rated 28"diam, 215x70x16, which is 10% taller than stock
The 215/65R16 has 1/2" less ground clearance than 215x70x16 ( the x65 has a slight clearance disadvantage offroad, but the x65 has a power and gearing advantage, better acceleration and torque than the x70).
For reference compared to stock of 25.5"
215x65x16= 27" (6% tall) D Rated
215x70x16= 28" (10% tall) C Rated
225x75x16= 29.3" (15% tall) E Rated _________________ My Soapboxes: Inflation; Handling; Gearing; Decoupling; Swepco |
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Syncroweekender Samba Member
Joined: March 12, 2013 Posts: 27
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Posted: Mon Mar 30, 2015 8:48 pm Post subject: |
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I have a Bridgestone Dueler A/T Revo 225/70R15 in my clamshell. According to the specs I found it is a bit smaller in diameter than the 215/75R15 BFG (27.4” vs 27.8”) but it is wider (9.1” vs 8.4”). I cut the clamshell pivot brackets off the top of the cross-member and had them welded on the bottom side. Then I pounded down the top of the box section (in front of the big tube) that the brackets are welded to in order to make room for the tire, cut the back edge of the clamshell off so it would pivot and ground a bit off the lower flange of the frame rails. I also had to use a spacer and a longer bolt in the front to close the clamshell. My tire fits pretty close to the frame and the steering shaft. It takes some trial and error to get the tire in the right spot. I strap the tire to the clamshell once it is in the right place so it doesn’t move on me and hit the steering shaft.
I could do a bit bigger diameter tire but I think it would probably have to be skinnier than my tire. I could take more off the lower flange of the frame rails but I think the back edge of a bigger tire would sit higher on the cross-member which reduces the clearance to the steering shaft.
Here a couple of pictures. Note that the clamshell pivot brackets sit lower than the cross-member.
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tjet Samba Member
Joined: June 10, 2014 Posts: 3533 Location: CA & NM
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Posted: Mon Jul 08, 2019 3:34 pm Post subject: |
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Christopher Schimke wrote: |
I run 235/65R17s which are almost identical in diameter to the 225/75R16. I run 5:43 R&Ps with stock gearsets and I think it's great. I have a bone stock 2.1 and have traveled all over, did Fins N Things in Moab, Fortune Creek Trail and Hawkins Mountain Mines Trail in the Cascades, including "Crankshaft Hill". This tire size and gear combo handled that and many other things really, really well and it drives great around town and on the highway too. Yes, there are compromises when going with larger tires, but when done correctly, there are benefits too.
I really like my combination and would definitely do it again. |
Thanks for your input. I really want to swap out my 4.86 R&P to a 5.43 when I do my trans. My current tires are around 29.5" tall. It's ok on flat roads though with my 2.2 wasser. |
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Steve Arndt Samba Member
Joined: August 01, 2005 Posts: 1780 Location: Boise, Idaho
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Posted: Mon Jul 08, 2019 3:53 pm Post subject: |
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tjet wrote: |
Thanks for your input. I really want to swap out my 4.86 R&P to a 5.43 when I do my trans. My current tires are around 29.5" tall. It's ok on flat roads though with my 2.2 wasser. |
Keep in mind on a Syncro you get to do that twice, front and rear gear boxes. It is $$$. _________________ Steve
Steve's 87 Syncro project |
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tjet Samba Member
Joined: June 10, 2014 Posts: 3533 Location: CA & NM
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Posted: Mon Jul 08, 2019 4:27 pm Post subject: Re: The Ultimate Syncro Big Tire/Gearing-is going big worth it? |
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Yeah there's that. I'm gonna try to recoup some costs by selling my matching 4.86 cores. |
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dkoesyncro Samba Member
Joined: December 10, 2006 Posts: 982
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Posted: Mon Jul 08, 2019 5:49 pm Post subject: Re: The Ultimate Syncro Big Tire/Gearing-is going big worth it? |
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I'd like to add "crawling" to this subject!
Im currently going through the syncro, we've got the gears figured out. The R/P are the next, I've been trying to locate 6.17. I've spanned far and wide. Weddle is an option but....this large investment of running gear and personal opinions of the respected say that the metallurgy of the Weddle is just not the same as the OEM. I have located a good used set in the UK but they are tentatively spoken for.
The respected is now looking to see if he has any 5.83, I have not scoured the Earth for these but, most of those I've spoke with far and wide also say this is difficult to find in good condition too! Yes, Weddle has this ratio but large investment...let's not leave things to chance.
The next thought, if a 4.86 and 5.43 are readily available with reputable quality, do these ratios produce the same amount of swarf backed to a diesel to provide the crawl-ability? |
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Steve Arndt Samba Member
Joined: August 01, 2005 Posts: 1780 Location: Boise, Idaho
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Posted: Tue Jul 09, 2019 9:41 am Post subject: Re: The Ultimate Syncro Big Tire/Gearing-is going big worth it? |
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There is more sliding vs rolling contact with the lower ratio r/p (higher number). So it is weaker because of smaller gear teeth, and has more wear due to the contact. _________________ Steve
Steve's 87 Syncro project |
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Sodo Samba Member
Joined: July 06, 2007 Posts: 9603 Location: Western WA
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Posted: Tue Jul 09, 2019 11:18 am Post subject: Re: The Ultimate Syncro Big Tire/Gearing-is going big worth it? |
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Steve Arndt wrote: |
There is more sliding vs rolling contact with the lower ratio r/p (higher number). So it is weaker because of smaller gear teeth, and has more wear due to the contact. |
I don't know if the teeth are smaller, but there's only 6 teeth on a 6.17, vs 7 teeth on the 5.43 and the 4.86.
The 6.17 has significantly more sliding contact thus more heat generated. Anecdotal evidence suggests the 5.43 runs hotter than the 4.86 too. _________________
'90 Westy EJ25, 2Peloquins, 3knobs, pressure-oiled GT mainshaft, filtered, cooled gearbox
'87 Tintop w 47k 53k, '12 SmallCar EJ25, cooled filtered gearbox
....KTMs, GasGas, SPOT mtb |
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tjet Samba Member
Joined: June 10, 2014 Posts: 3533 Location: CA & NM
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Posted: Tue Jul 09, 2019 11:29 am Post subject: Re: The Ultimate Syncro Big Tire/Gearing-is going big worth it? |
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Wouldn't a lower R&P gearset (higher numerically) not be as stressed as a taller stock gear?
Also, I didn't think the ring and pinion was the main failure issue with these transmissions.
I'm wondering if a cryo treatment would help these gears... |
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Sodo Samba Member
Joined: July 06, 2007 Posts: 9603 Location: Western WA
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Posted: Tue Jul 09, 2019 12:22 pm Post subject: Re: The Ultimate Syncro Big Tire/Gearing-is going big worth it? |
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tjet wrote: |
Wouldn't a lower R&P gearset (higher numerically) not be as stressed as a taller stock gear? |
Yeah, but not if you put it back with larger diameter tires. And the 6.17 has only 6 teeth to the 5.43 and 4.86 7 teeth. So by tooth count alone, 6 teeth has to be about 17% higher tooth pressure. And there's much more sliding too on a 6.17. The 6.17 hypoid has some wild sliding like 40% vs 23% for a 4.86 hypoid.
There's no free lunch with big wheels. But ya gotta do what ya gotta do, right?
tjet wrote: |
Also, I didn't think the ring and pinion was the main failure issue with these transmissions.
I'm wondering if a cryo treatment would help these gears... |
4.86 run long, 300,000+ even in the US where the gear oil is not changed. But now they're all getting big engines hung on so they're taking a beating in later life. I don't know how 5.43 (Europe) compares or if Europeans maintain their transaxles better.
That's an interesting thought, I wonder how much it costs to take a new Weddle set and send it out for Cryo? ....and if that would help? _________________
'90 Westy EJ25, 2Peloquins, 3knobs, pressure-oiled GT mainshaft, filtered, cooled gearbox
'87 Tintop w 47k 53k, '12 SmallCar EJ25, cooled filtered gearbox
....KTMs, GasGas, SPOT mtb |
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Steve Arndt Samba Member
Joined: August 01, 2005 Posts: 1780 Location: Boise, Idaho
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Posted: Tue Jul 09, 2019 12:54 pm Post subject: Re: The Ultimate Syncro Big Tire/Gearing-is going big worth it? |
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My experience is with T1 and 091 boxes mainly. The rule of thumb (ish) is smaller number lower ratio is stronger.
It depends on the tooth cut profile as well. _________________ Steve
Steve's 87 Syncro project |
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tjet Samba Member
Joined: June 10, 2014 Posts: 3533 Location: CA & NM
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Posted: Tue Jul 09, 2019 12:55 pm Post subject: Re: The Ultimate Syncro Big Tire/Gearing-is going big worth it? |
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I've also read about a process that bakes and the part before the Cryo treatment. They do this before final machining. |
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Steve Arndt Samba Member
Joined: August 01, 2005 Posts: 1780 Location: Boise, Idaho
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esmukarlis Samba Member
Joined: September 04, 2017 Posts: 10 Location: Europe, Latvia
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Posted: Wed Aug 14, 2019 10:39 am Post subject: Re: The Ultimate Syncro Big Tire/Gearing-is going big worth it? |
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Didn't want to make a new topic and this seemed as good one to put my question.
I am building Syncro for overlanding around North and South Americas and currently going through trans rebuild.
I plan to go with 1z TDI engine (around 90hp), 215/75/R15 tyres (27,7"). I have gearbox with 4,83 R&P ratio. My question form personal experience of some of you - should I go with 0.7 or 0.74 4th gear. I know its not a big difference, but maybe someone used one of them and now are 100% sure, that other one would be best fit for them! |
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FrankenSubySyncro Samba Member
Joined: May 03, 2007 Posts: 638 Location: Vancouver, WA.
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Posted: Thu Aug 15, 2019 2:17 am Post subject: Re: The Ultimate Syncro Big Tire/Gearing-is going big worth it? |
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esmukarlis wrote: |
Didn't want to make a new topic and this seemed as good one to put my question.
I am building Syncro for overlanding around North and South Americas and currently going through trans rebuild.
I plan to go with 1z TDI engine (around 90hp), 215/75/R15 tyres (27,7"). I have gearbox with 4,83 R&P ratio. My question form personal experience of some of you - should I go with 0.7 or 0.74 4th gear. I know its not a big difference, but maybe someone used one of them and now are 100% sure, that other one would be best fit for them! |
I have 6.17 R&P with the .73 4th and 30" bfg KM2 tires and subaru 2.5. I have also ran 225/75/16 bfg KO2s. I travel with 3 other syncros that also have 6.17 but smaller tires and .70 4th. I don't have to downshift as soon as them and sometimes not at all when climbing steep long grades on the highway (Grants pass in southern Oregon). We communicate frequently with CBs. We discuss rpms, trans temp, engine temp with climbing grades.
Its interesting to compare stats on similar vehicles in similar conditions. One of the syncros has a GoWesty 2.5.
I chose 6.17 for the lowest low gear ratio (off road crawling) but had to change 2, 3, and 4th gears and add a trans cooler. I recommend a trans cooler for anything lower than 4.86 (higher number). _________________ Syncronize it!
1987 Franken Syncro (converted 2WD auto)
2004 2.5 SOHC Subaru
F & R lockers, decoupler, SS, 6.17 R&P
Trans Cooler
EMPI race prepped 930 CVs and axles
Bilstein coilover front, rear ProComp MX-6066R shocks, 14" hypercoil springs
30x9.5 15" BFG Muds
Custom skid plates
Nose job (custom front bumper) http://www.flickr.com/photos/subyvanagon/sets/72157624970330925/ |
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