Dana 27 |
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NCtoy
Member Joined: 28 Aug. 2005 Location: NC Status: Offline Points: 507 |
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Posted: 28 Apr. 2018 at 3:07pm |
Been thinking about something for a while, but the Dana 30 thread has me second guessing myself. I’d like to do a couple upgrades to my front end. I have most everything I need for an 11 inch brake upgrade, and I’d really like to put a locker or limited slip in. I have 2 problems with this and my current set up: first my front end has the early style knuckles with the steering arms mounted on top, which won’t clear the 11 in backing plates. Secondly, I’m not wild about a full locker in the front with stock steering, or really having one without a cage. I do have a roll bar I can put in for trail riding, but we all know it’s not the same.
Now my plan was to take a Dana 27 out of a cj5 I’m parting out, and build it with the 11 inch brakes, and one of the NOS power locks from QTM. I would have to regear this axle as it’s currently 4.27 gears. But the Dana 30 thread has me thinking maybe I should just use one of those. The biggest downside there is the cost, but I could offset some of it by selling the Dana 27. I also don’t really want the extra width making it look goofy, although it would come in handy in off camber situations. I guess I could use spacers in the back, but I’m trying to keep as close to a stock look as possible. I’m not planning on a hardcore crawler, just want to be able to hit some trails. Currently running a 225, t90, and 7.00-16s but I have thought about getting a small set of swampers for off road use. Maybe a terra low gear set later. Is there any strength advantage in the 27 over a 25? Will a 27 hold up to wheeling on 31 or 32” tires? Not too sure which way to go now.
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oldtime
Member Joined: 12 Sep. 2009 Location: Missouri Status: Offline Points: 4183 |
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There are distinct advantages and disadvantages between the D25, D27 and NT D30 axles. STEERING D25 and D27 obviously having the narrowest track width. Both D25 and D27 may slightly limit your steer angle when running 7.00 x 16 tires. It is both the tire diameter and the actual tread width that actually limits the allowable steering angle. NDT's and NDCC's tend to have a very narrow tread width as compared to most of the M/S tires. If you go to Interco 34" NSS tires then the D30 will provide "much" improved steer angles over the the earlier axles. You probably have inferior 23* Bendix shafts in your early D25 assembly. The D27 will almost certainly have a set of 27-1/2* Spicer axle shafts in it. Rzeppa shafts will provide the most steer angle but you can't use the full 29* angle with tires over 6.50 x 16".LIMITED SLIP The QTM availability / price of D27 limited slips certainly seems like a good deal. Expect D25 and D30 limited slips will be much more difficult and costly to locate. All of the D25, D27, D30 Powr Loks use the exact same set of clutch disks. BRAKES All three axles will readily adapt to the 11" Bendix system You could put the D27 knuckles on your early D25 assembly to eliminate the top mount steer arm interference. STRENGTH I prefer the D25 over the D27. It has a larger therefore a stronger ring /pinion than a D27. D27 has different hubs than a D25 however the spindles remain the same.. Larger hubs means slightly wider (stronger) wheel bearings and larger spindle seals. The D27 will be all RH lug threads The D27 hubs can readily be swapped onto a D25 assembly. Here again the Rzeppa shafts will be the strongest available. A D30 will have somewhat stronger shafts and knuckles than the earlier axles. GEARING With a Dauntless you can run just about any ratio from 5.38 through 3.54. 5.38 ratio is best for 134 engines and rock crawlers. 4.88 is an excellent ratio if combined with 25% O.D. 4.27 and 4.09 are great compromise ratios (Off-road to street) not having an O.D.unit 3.73 ande 3.54 are best for road use and when used with D20 transfer cases that have low gears. For D25 5.38 and 4.88 ratios are most common. For D27 5.38 is rare while 4,27 and 4.88 and 3.73 are common. For D30 3.73 (pre 1976) is standard 4.27 was optional and 3.54 was standard after 1975. 55/1 is a great crawl ratio for "TRAIL JEEPS" not destined to become a rock crawler. |
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Currently building my final F-134 powered 3B .
T98-A Rock Crawler using exclusive factory parts and Approved Special Equipment from the Willys Motors era (1953-1963) Zero aftermarket parts |
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flatfender47
Member Sponsor Member Joined: 09 Jan. 2006 Location: Riverside CA Status: Offline Points: 646 |
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Per your comments I think the D27 is the way for you to go.
11" brakes and a Powr Lok will be good upgrades. Plenty of those axles running around with 31 or 33 tires on them. If you're running 5.38's, I wouldn't bother with the terra low gears. I'd change the steering tie rode while you're at it. If you can find a double hole knuckle, so much the better.
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1947 CJ2A 225V6 SM420 D30 PLok/D44 D/Locker Warn OD 5:38s
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Nothing Special
Member Joined: 02 Feb. 2018 Location: Roseville, MN Status: Offline Points: 843 |
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Everyone has their own opinion, and even I know that just because this one is mine doesn't make it right But in my opinion, there's really no use where a clutch-type limited slip isn't the worst possible option. In a front axle, any time your hubs are locked (or all the time if you don't have hubs to unlock) you will be fighting the limited slip in all turns. The tires have to go different speeds and the clutch in the limited slip needs to be slipped for that to happen. If the clutches are very "loose", then that won't be much of a problem, but then again, if they are loose the limited slip won't help much. Personally (again, my opinion), I'd rather have either an open diff or an automatic locker. The open diff will give the best manners, but give slightly worse traction than a limited slip on tougher trails. The automatic locker will always give better manners than a limited slip when you are in 2WD with the hubs locked, and will often give better manners than a tight limited slip when you are in 4WD (but not as good as an open diff) and will give much better traction than either on tough trails. My choice for lighter trail use has been an open diff in the front and a locker in the rear. I feel that gives almost as good manners as stock, I don't find it to hurt turning radius too much (although an automatic locker in the rear will tend push you straight to some degree when powering through a turn). As far as a locker without a roll bar or cage, you're only more likely to roll if you push it. And with a locker you can often go slower over the rough stuff, making it easier to stay in control and not roll. So I wouldn't feel like a locker makes rolling more likely. And again, I know others have different opinions. I'm not saying they are wrong, or that you will agree with me instead of them. I'm just giving my thoughts. edit to add: A selectable locker is an option in a Dana 30. I don't think it is in a 25 or 27 (although I could be wrong about that). There are a few threads that have discussed the pros and cons of selectable vs automatic lockers in front and/or rear, so I won't go into that here. I focused on automatic lockers because they are the most readily available.
Edited by Nothing Special - 29 Apr. 2018 at 3:51am |
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Metcalf
Member Sponsor Member Joined: 21 May 2009 Location: Durango, Co Status: Offline Points: 736 |
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You can mod a 27 powr-lok to fit in a 25. People been doing it for decades.
Herm even offers a bearing kit now that doesn't require machine work. |
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42 MB that had a one night stand with a much younger 69 CJ5 and a 50s GM truck.
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NCtoy
Member Joined: 28 Aug. 2005 Location: NC Status: Offline Points: 507 |
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NCtoy
Member Joined: 28 Aug. 2005 Location: NC Status: Offline Points: 507 |
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Metcalf,
I looked at that kit and some of the stuff on the conversion, but it’s still not clear exactly what mods still have to be done. Some people said nothing, others had to machine the carrier, or the axle shafts. I’d really like to be able to use off the shelf parts though, in case of breakage. Also, I’d still have to change at least the knuckles to fit the 11 in brakes. Are you the one that was making the disk brake conversion brackets? Any idea if that will work with the early style knuckles?
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Spinnas
Member Joined: 24 Apr. 2018 Location: AZ Status: Offline Points: 375 |
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In regards to all the locker talk, here's some info. Of course an open diff is gonna drive the best on road. A limited slip is actually not as bad as it's being made out to be unless it's so tight that it's practically a locker. Of course if it is loose, it's not gonna be much better than an open diff offroad. Auto lockers like a Detroit are unpredictable and if driven on the street in 4wd in a front axle suuuuuuuuck. I am a rock crawler/buggy guy and my motto is spool or selectable, that way it's either open or a spool. You always know what it will do. Lunchbox lockers are ok but if driven a lot(in a front end that is spinning the axles) will start to wear the gears out to the point they stop working. When contemplating putting a single locker in either a front axle or rear axle, the answer is front axle hands down, no question. Ask yourself this: Is it easier to pull a cart through loose ground or push a cart? I take the local U of A offroad club out on some trails once a year to challenge them. Most are of course broke college kids with TJs on 33s and 35s with a front lunchbox locker open rear. Some have a locked rear open front. The front locker rigs far out perform the locked rear rigs cause the rear isn't pushing. Most of the time in buggies I am driving locked front open rear and only lock the rear when needed. The maneuverability is phenominal compared to the opposite. It's actually quite surprising what you can drive through with that combo.
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Metcalf
Member Sponsor Member Joined: 21 May 2009 Location: Durango, Co Status: Offline Points: 736 |
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Yup, that's me. My disc brake conversion works on 1941-86 front axles, and also up to about 1970 rear axles. You can also use them on rear axles that have been converted to full float. I basically use geo tracker or Suzuki sidekick parts. The conversion is very easy. The hardest part is removing the drum brake stuff. |
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42 MB that had a one night stand with a much younger 69 CJ5 and a 50s GM truck.
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Metcalf
Member Sponsor Member Joined: 21 May 2009 Location: Durango, Co Status: Offline Points: 736 |
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I agree 100% with the front locker first philosophy. I agree about 0% with the automatic locker in front ( as long as the rear end is open ) sucking. I've but thousands of miles on that combo with very few drawbacks...rock, mud, snow, roads, etc. As long as the rear end is open the front axle is happy just doing its lock-unlock thing all by itself. There is a little extra steering feedback, but the vehicle just goes where I point the front tires. I think the front automatic works better in a lot of situations vs a front selectable or spool. You can get around some of it with LOTS of steering force, but the automatic locker seems very happy to do its UNLOCK thing vs a selectable. I see tons of issues with selectable lockers not wanting to unlock when bound up, especially when being pushed by a rear end with an activated selectable locker, automatic locker, or spool. The steering action can actually cause an unlock in the ratchet mechanism on an automatic locker, but causes more binding on a selectable locker most of the time. Just my counterpoint. |
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42 MB that had a one night stand with a much younger 69 CJ5 and a 50s GM truck.
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Nothing Special
Member Joined: 02 Feb. 2018 Location: Roseville, MN Status: Offline Points: 843 |
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Lunchbox lockers are automatic lockers like a Detroit. If you don't like a Detroit you won't like a lunchbox either. And as far as them wearing out, I put about 100,000 miles on one in the rear axle of an F-150. It still worked fine. Your mileage may vary. |
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Metcalf
Member Sponsor Member Joined: 21 May 2009 Location: Durango, Co Status: Offline Points: 736 |
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Someone needs to have a set of alloy axles cut that fit in a 25/27. Stock would still swap, but I suspect a good alloy shaft would be a huge improvement to a known weak area. You could change to a 27 spline outer design with a later model locking hub also. I wonder how close a stock D30 outer stub would be? I believe the large 297/760 joint will fit through the spindle locating bore also. Then it would only be a matter of seeing if it would fit in the ball also.
The ring gear probably isn't the weak point, I think the carrier/locker would still be. The powr-lok carrier is probably the strongest option. I wonder if Dana 30 27 spline Powr-lok side gears would fit in a Dana 27 powr-lok case? Honestly though. This all makes a Dana 30 look like a really nice swap. |
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42 MB that had a one night stand with a much younger 69 CJ5 and a 50s GM truck.
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Spinnas
Member Joined: 24 Apr. 2018 Location: AZ Status: Offline Points: 375 |
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I bet the 297/760 joint fits, it’s just a 1/8” bigger cap with bigger trunnions over the 260, same overall length dimension. Slightly wider yokes on the shafts. I was at Willy’s Works the other day and Rob has a 71? D30 I think it is. He said it’s the 1 year that was open knuckle and old narrow perch width or something along those lines. Basically no knuckle balls and all common D30 parts.
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Metcalf
Member Sponsor Member Joined: 21 May 2009 Location: Durango, Co Status: Offline Points: 736 |
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I have a narrow track D30 in my flatty. The spring center width is the same on all of them I believe. The narrow track version is about 53.5" wide to the WMS. They are a great axle for a flatty in my opinion. The only annoying part is that it is about 2.5" wider than the stock axle depending on brakes. Plenty of ways to make the rear axle a little wider including a full float conversion, which is what I did.
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42 MB that had a one night stand with a much younger 69 CJ5 and a 50s GM truck.
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NCtoy
Member Joined: 28 Aug. 2005 Location: NC Status: Offline Points: 507 |
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Lots of good info here. Now I’m even more unsure which way to go with my plan though. Haha
After reading about experiences with automatic lockers in the front only, I’m getting tempted to just put a locker in the front instead of a power lock. If I go that route, I have a Dana 25 with the 5.38 gears and the right knuckles for the 11 inch brakes laying in my shed. So I could conceivably build that for less $ of any other option. But then I’m stuck with the weaker joints and axles. But I think with the level of wheeling I have planned the 30 is probably overkill.
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Spinnas
Member Joined: 24 Apr. 2018 Location: AZ Status: Offline Points: 375 |
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Didn't know the WMS change but good info. Not too familiar with the "later" stuff till you get to YJs and TJs.
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Anvil
Member Joined: 07 June 2017 Location: Colorado Status: Offline Points: 326 |
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Metcalf, are you running a Detroit in your front or another brand?
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Metcalf
Member Sponsor Member Joined: 21 May 2009 Location: Durango, Co Status: Offline Points: 736 |
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It is just a Yukon Spartan lunchbox style locker. I fully expected it to blow up by now, but here I am 5+ years later with MANY trail miles later and zero issues. When (?) it does finally give out or I chicken out, I would replace it with a Yukon Grizzly Locker. I believe the Grizzly is a little more durable vs the Detroit. They both function very similar, but I think the Grizzly is also a little better at unlocking technically ( but maybe at the expense of slightly more noise ). Detroit has rolled most of their offerings to the 'soft-locker' style technology to make them behave a bit better when used in rear applications. |
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42 MB that had a one night stand with a much younger 69 CJ5 and a 50s GM truck.
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