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Bill Davis (Gbrbill)
| | Posted on Wednesday, November 13, 2002 - 11:36 am: | 
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List
I was out of town at the SEMA show last week so I am further behind than normal and haven't been able to follow up on the discussion from a couple of weeks ago. Someone told me that there were several questions to some of my comments but I can't find the original topics and keep crashing my computer trying to access the archive. Any suggestions on how to find those posts would be apprciated. |
nadim
| | Posted on Wednesday, November 13, 2002 - 12:33 pm: |
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Bill,
I think it'll be best if you explain to us the difference between the stock Disco CVs, the early D110s ones, the Longfielded ones, and your HD ones. Are there any others? and what about the half shafts?
 , guess that'll cover it all!
Thanks! |
Greg Davis (Gregdavis)
| | Posted on Wednesday, November 13, 2002 - 02:35 pm: |
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Well, my question was what would be recommended for a DII that will be running 36's on the trail and 33's on the street. What would you suggest as far as axles, gears, etc? I've been thinking of regearing the t-box (or installing an underdrive) rather than regearing the axles. Your thoughts on that approach? |
muskyman
| | Posted on Wednesday, November 13, 2002 - 02:56 pm: |
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while you are at it bill?
all diffs have a design optimum for gear ratio as far as strength goes..ie 3.73 to 1 is the strongest gear set you can get for a dana 60(according to DANA).
what is the design optimum ratio for the rover axle? |
muskyman
| | Posted on Thursday, November 14, 2002 - 01:09 am: |
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bump |
Bill Davis (Gbrbill)
| | Posted on Thursday, November 14, 2002 - 02:06 am: |
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Nadim
Let me apologize in advance to you for fiddling around on this list instead of responding to your direct off line request for info. I am completely over worked and totally behind in everything but find this public stuff relaxing (am I sick or what!) so I'm really doing stress relief now. Anyway on to the questions.
Stock CV's - good for stock vehicles and light offroading. Very iffy on a rig with a fully locked front diff. Its way to easy to forget to turn it off when you are turning on a high traction surface or you remember but theres too much windup for it to release. The issue with them is that they are a mass produced part i.e. less than perfect machining and heat treat. The material is nothing special either. Also have the problem of having a very small (.885 inch) inner axle at the CV joint. Thats smaller than a VW Rabbit. Rover went to this size inner axle/CV across the board in 1989. Not sure why but all of the earlier axles/CV's were the bigger 1.195 inch 23 spline stuff
Early 110 - slightly stronger CV joint, although with all of the same shortcomings of the stock Disco CV i.e. mass production but the big difference is the diameter of the inner axle. Its the earlier larger 23 spline diameter. Bear in mind there are two weak points in the front axle assembly, the inner axle and CV and you need to beef up both or the overall assembly isn't any stronger. This combo does beef up both components assuming you use an aftermarket axle shaft that is 24 spline on the diff. The factory never made this combo.
The problem with this set up is that you are trying to install a CV joint that was never intended to go into this particular axle assembly (anything other than a Defender 110/130) so you end up having to use a bunch of bits and pieces to make it work. There are a couple of different ways to do it but regardless of which way you choose all of these bits and pieces end up adding a bunch of extra expense to the project. Also you run into issues such ABS systems, which this CV joint wasn't designed to function in conjunction with. The ABS can be made to function by installing a ring around the joint with the 60 ABS marks but it also adds some more expense and a heap of it at that. It also introduces another problem in that the outside diameter of the CV joint is too large for the swivel housing so you have to assemble the swivel housing around the CV joint instead of just installing the CV joint into an already assembled swivel housing. This makes for some very time consuming trail fixes if you ever break one since you have to disassemble the entire swivel housing to remove the broken parts. Think about what kind of mood the spouse is going to be in after a 4 hour trail fix! You also have to grind some material out of the inside of the swivel housing during the initial install so the ABS ring doesn't contact the swivel housing at full lock. Remember all of this because this is also an issue for "longfielded" CV joints but we'll get to those in a minute. One last minor issue with the ABS is that since the CV OD is larger you also have to raise the ABS sensor so it doesn't get whacked during the first revolution of the CV.
LongFielded CV's - The theory of Longfielded CV's is that you weld a band around the outer edge of the CV bell (technically called the outer race). This strengthens the CV but actually only when you have the wheels turned at full lock, which is when you are putting a lot of stress on this part of the joint and when its most vulnerable to breakage. Its a good thing to remember when off roading i.e. if your front tires are at full lock, use the throttle carefully, your CV's will like you more! When the CV's are in a straight ahead position, longfielding doesn't do a damn bit of good.
The first problem with "longfielding" a Rover CV joint is that you are making the OD of the CV joint larger and you immediately run into all of the issues discussed in the last paragraph. In the interests of brevity, I won't repeat them and will suggest that you reread the previous paragraph.
The second problem with longfielding a Rover CV, specificly anything with ABS, is that you pretty much eliminate it because the ABS "marks" are exactly where the ring is welded onto the CV. I suppose you could machine the marks back in but that going to be expensive. Don't forget to raise the sensor either.
Longfielding works reasonably well on a Toyota because they have lots of extra clearance in the swivel housing. As far as I'm concerned longfielding just isn't an option for a Rover. I also have issues with welding on a previously machined/heat treated part. I know a little bit about heat treating and welding on a heat treated part introduces some major stress issues with the grain structures etc. The only way to deal with it is to do some stress relieving processes such reheat treating or cryoing them. I also can't belive that they will longfield a used CV joint. A CV joint is a wear item.
My HD CV's - This whole process of building better CV's has gone thru an evolutionaly process with both the smaller 32 spline version and also the larger 23 spline ones. First we built better cages but found that it was in reality a small incremental increase in durability not the hoped for "giant" step. Next we dealt with the issues that resulted from the mass production issues discussed earlier by employing some very high tech (and expensive) metalurgical precesses to correct some of these inherent problems. We ended up with some pretty decent CV's but they both still had some problems. On the 32 spline version, you still had the VW Rabbit sized inner axle and in spite of using some very good material for the inner axles they were still Rabbit sized.
With the 23 spline version, you still needed all of the bits and pieces and hence expense to make them work so its still an expensive option.
Also they were both made from 8620 commercial grade case hardening steel and you can do all of the high tech stuff to them that you want, but at the end of the day its still 8620 case hardening steel (Alchemy was disproved in the early 19th century). All this lead to the obvious conclusion - make a completely custom CV joint, which is the next category.
My Custom HD CV's - These are completely custom CV joints where we picked out own material, designed them to be a complete bolt in i.e no extra bits and pieces, they use the much larger 23 spline inner axle and they are less expensive than any other previous kit I have offered. As usual with with a project such as this, it is behind schedule. I was hoping to have these available a couple of months ago but it has been going slower than expected. They are in the final manufacturing stages and I hope to have them in a couple of weeks.
As far as axles go, better material makes better axles. We use AMS grade steel (aerospace material spec) in all of our coiler axles and the axles that go with these Cv's are no exception
All for now, I'll get to the other questions in the morning
Bill
GBR |
Moe
| | Posted on Thursday, November 14, 2002 - 10:05 am: |
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Great information, Bill.
I was led to believe that Longfielding the stock CVs does not interfere with the ABS ring and that the extra band is welded alongside the ABS ring?
I don't yet own a set of longfields and have only spoken once to Bobby, but I believe he does heat treat/cryo the star and the cage although I am not sure about the CV bell. It would be great to hear from someone runnging Longfielded stock LR CVs. |
Bill Davis (Gbrbill)
| | Posted on Thursday, November 14, 2002 - 10:35 pm: |
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Greg
Someone asked me if I was related to you the other day. Don't think so but most folks don't realize how many Davis's there are in the world! My fathers family owned a huge plantation in Virginia before the civil war and had several thousand slaves if you have ever wondered why so many black folks are named Davis.
Anyway on to your questions. I would definitely regear the diffs before you start on the transfer case. Reason being is that regearing the diffs will give you benefits in both low and high range and in all honestly probably more in high range. With the tires you have, if you do the diffs the rig will feel like it has 30 more HP in high range and will cruise much better at highway speeds and won't shift around nearly as much trying to find the correct gear. You will also have better low speed control and power in low range. Slightly better compression braking but lets face it a little better of none isn't much improvement.
A low range kit really drops your low range (-31%) but doesn't affect high range and my guess is you use the rig on road far more than off road. Do the diffs first and if you want/need more low range install a low range kit later. In my opnion the ideal gearing for a late model Rover is 4.11 diff gears with a low range kit.
I'd forget the underdrive, they are way to low (124 to 1) in addition to being expensive and very difficult to fit in anything other than a Defender. If competition rockcrawlers only need 90 to 1 with an automatic trans, why would you need anymore than that. Unless of coarse you just like the look of lots of levers. Nothing wrong with that, I have a Series Rover with the three usual lever plus an overdrive, PTO winch and hydraulic plow controls. The cab has enough levers, you would think you were in a backhoe! You would have to flatbed it to steal it, the average person wouldn't have any idea how to operate it especially since it has the old style push button starteron top of all of the levers. In my opinion, the only advantage of an underdrive compared to a low range kit is that you get another cool lever.
The most important determing factor for upgraded axles/CV's is whther you have diff locks. Reason being is you can transfer a much greater percentage of torque to a single axle shaft. ETC counts. Tires size is not as big a factor as the diffs.
Wifes home - all for now
Bill
GBR |
Shane
| | Posted on Friday, November 15, 2002 - 02:43 am: |
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Longfielding corrections:
It sound as though Bill is mistaking Longfields for Marfields.
Marfields use a band around the CV bell similar to Bill adding the ABS ring the the 110 CV's.
Longfields weld a ring on the end of the bell increasing it's length by approx 1/4"
Bobby Long also reheat treats and cryo's parts of the CV for added strength.
He has sold over 1500 units to the toyota guys and has had less than 15 units fail. This is including those that are using them in Rock Crawling competions. Did I mention lots of these guys run 38.5" swampers? He also has a WARRANTEE of free one time replacement for the toyota guys. Since he doesn't have any rover CV's he is only offering free treatment of a replacement set of CV's should you break a longfield. The current (treatment)price is $125.00 ea
http://www.longfieldsuperaxles.com
I have no affiliation with above bla bla bla...
just like to see some viable options. |
Greg Davis (Gregdavis)
| | Posted on Friday, November 15, 2002 - 09:17 am: |
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Bill, thanks for all of the info. My father's ancestors came from Scotland (Davies) in the early 1700's and settled along the Cape Fear river. Yes, there's a ton of Davis', and my father's name is Bill (William) also!
Back to the real info. Thanks for the advice on the R&P's vs. the underdrive. I DO like levers, but what you said makes sense.
I have a Detroit in the rear and a TT up front. Is that good or bad for my stock axles? That has been discussed before, and some feel that lockers help prolong the stock shafts because you tend to "ease" over the obstacles rather than having to "flog" your vehicle to make it through. And others profess just the opposite. What's your take? |
Bill Davis (Gbrbill)
| | Posted on Friday, November 15, 2002 - 12:08 pm: |
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Muskyman
Don't have any idea of the design optimum for a Rover R&P is. I suspect its somewhere in the mid to high threes. If my memmory serves me correctly, its a ratio between the strength of the pinion gear, which gets smaller as the numeric ratio goes up and the ring gear which gets thinner as the numeric ratio goes down.
I don't think its that important because I personally would buy gears based on what ratio I needed as opposed to buying them based on a design optimum and ending up with a ratio that didn't work for my gearing needs.
Your Dana example is a perfect example, Dana 3.73 gears was a very rare ratio from folks that used lots of Dana 60's. They were available as on option on some Chev/GMC trucks for just a few years. I found this out when a friend of mine in Australia wanted me to locate him a good used set in the US. Had to look high and low for them.
Bill
GBR |
thom mathie (Muskyman)
| | Posted on Friday, November 15, 2002 - 12:27 pm: |
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thanks bill just wondering from a total drivline viewpoint.
i would rather balence the reduction on a truck with oversized tires as aposed to putting a huge reduction in the axels and none in the •••••• or TC.some people say it dosent matter where you get the gear reduction, i have had a very different expierience. i blew up a number 4.88 and 5.13 gear sets over the years now with a deeper •••••• and deeper TC gears and 3.73 in my D60's I have had no drivline breakage in years. its just more balenced.
also if you need some more of those 3.73 dana 60 gears give me a e-mail I have a source for OEM Dana gears for about $125 a set |
Bill Davis (Gbrbill)
| | Posted on Thursday, November 21, 2002 - 10:14 pm: |
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Shane
I didn't know you were on this list and I stand corrected concerning longfielding vs marfielding. I have to admit I'm not an authority on Toyota CV joints. Bearing this in mind, I don't think that marfielding would work very well on a Rover CV joint with ABS because for the band to be effective it would have to go where the ABS marks are. It would probably help a 110 CV a little bit. I also suspect that a longfielded CV joint with a 1/4 inch extension would also run into clearance issues also but can't say for sure since I haven't tried it.
I don't think either method would be particularly effective on a Rover CV joint, forgetting the clearance issues for a second, because experience has shown that the parts that usually fail on Rover CV joints are the internal components - star and cage. THe bells do fail but its usually because the internal parts go first and bind up and then damage the bell. No point in having a super strong bell and having the internal stuff still breaking.
Bill
GBR |
Bill Davis (Gbrbill)
| | Posted on Friday, November 22, 2002 - 01:21 am: |
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Greg
My relatives hail from primarily Wales and England although knowing some of the history of the area, I'm sure a few Scots are in the mix somewhere. are you sure your not a McDavis?
Heres my opinion on traction diffs and axle shaft durability. On the one hand a traction diff will reduce some of the stresses on the vehicle by allowing you to negotiate more difficult obstacles at a lower speed i.e. they reduce the need to use momentum. This will reduce the stresses on drivetrain parts, suspension components and even body panels. But on the other hand a traction differential will transfer a much greater % of engine torque to a single axle shaft - up to 100%. An open diff can never do this because once you exceed a 50/50 torque split side to side, all of the torque will quickly be directed to the axle shaft/tire with no traction resulting in that tire starting to spin at double the rate of speed going into it. If it hits a high traction surface and suddendly stops this is not good for an axle shaft but its actualy far harder on the open diff carrier because it wil instantly try to direct that torque to the other axle shaft. This puts a tremendous strain on the cross shaft. This is why stock open carriers frequently fail due to broken cross shafts.
Imagine this extreme but fairly common example, you are negotiating a very steep, dry, high traction section of trail in a vehicle with a fully locking rear diff. At the same instant, your front wheels simultaniously hit a small step that bounces your front end up a little and which essentially unweights the tires, meaning that all of the vehicle weight shifts to the rear tires At this same instant one of your rear tires hits a patch of gravel and loses all traction. At that instant all of the vehicle weight and power are being transmitted thru a single rear axle shaft. This is what dramaticly increases the stresses on axle shafts with traction diffs. This same scenario can never happen with open diffs because all of the power would instantly shift to the rear tire losing traction and most likely forward motion would cease.
In conclusion, a traction diff will in some cases reduce some drivetrain stress but overall they will substantially increase them.
Your stock axles are on borrowed time.
Bill
GBR |
Bill Davis (Gbrbill)
| | Posted on Friday, November 22, 2002 - 01:29 am: |
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Thom aka muskyman
I agree with you about balancing your grearing needs between components. If you try to get it all thru diffs you end up losing some durabilty. An example is 4.11 vs 4.75 diff gears. A 4.11 is an inherently stronger gear due to its larger pinion. I would prefer to to have 4.11 gears with a low range t-case than 4.75 diff gears. In addition to being stronger, you end up with much lower gearing to boot.
Bill
GBR |
Chris Browne
| | Posted on Friday, November 22, 2002 - 06:03 am: |
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I think Bill's thoughts on 4.1 v 4.75 is echoed by Mike Smith at ECR....just too little meat on the 4.75 for comfort or strength.. |
Greg Davis (Gregdavis)
| | Posted on Friday, November 22, 2002 - 09:04 am: |
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Thanks for all of your input Bill, it's truly appreciated. Time to start saving for those axles. |
Curtis N (Curtis)
| | Posted on Saturday, November 23, 2002 - 01:45 am: |
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I don't thnk I have ever said this on this board, but I will be damned if this is not the most informative thread I have ever read. Thanks especially to Bill. I will need to drop in soon to discuss the axles and CV's.
Curtis |
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