TooTallMike Posted January 25, 2007 Share Posted January 25, 2007 Question initially directed to Karoshi but all are invited to input: K - I saw on CCKW.org that you were after a pair of drive flanges for a split axle GMC. Firstly, I think I have a pair along with a pile of other bits which I want to sell, if you didn't get any. I'll get some pic's once the snow is gone. Secondly - were you by any chance planning on doing Dr Deuce's dummy drive flange conversion? If so, does it work and are there any wear issues? I want to do a similar thing on the wrecker but I'm concerned about the splined halfshafts wearing their way through the dummy tube. For anyone who doesn't know what all this is about - GMC front axle drive is transmitted to the hubs via the drive flanges at the extreme ends of the axle. They have an internally splined tube which mates with the halfshaft, and they bolt to the outer face of the hub. To avoid having the front diff and prop running constantly the suggestion is to obtain a spare pair of flanges and machine out the internal splines so that they are plain tubes. The halfshaft then floats inside without turning the diff or prop. If you plan to go off road you just swap the dummy flanges for the originals and engage 6x6. Any comments welcome. Quote Link to comment Share on other sites More sharing options...
Bodge Deep Posted January 25, 2007 Share Posted January 25, 2007 Sounds about right. I bought some for the dodge (they were made for operating M37s on road conditions) But I couldn't use them as I need 4X4 to get the Dodge into the barn it lives in, so sold them on... (got lockouts on now) but they were essentially that... an end cap without the splines... my mate has them on his... no problems reported so far. Quote Link to comment Share on other sites More sharing options...
Jack Posted January 25, 2007 Share Posted January 25, 2007 Interesting Mike. What is the project brief? How difficult is it to do? How much? How big are the benefits? etc etc............ Cheers Jack Quote Link to comment Share on other sites More sharing options...
Bodge Deep Posted January 25, 2007 Share Posted January 25, 2007 Should help a little with fuel consumption... a little Even in 2WD (or with AWD disabled as in a 3 axle truck) the front transmission is pushed around by the front wheels (half shafts, diff & propshaft) all the way up to up to the transfer box. Disconnecting the hubs from the shafts (which is what machined out hubs/lockouts effectively does) & all that rolling resistance is lost. Jack up y'truck in 2WD & spin the front wheels by hand for an idea of how much resistance it offers. Quote Link to comment Share on other sites More sharing options...
Enigma Posted January 25, 2007 Share Posted January 25, 2007 It may also reduce noise levels. Quote Link to comment Share on other sites More sharing options...
Bodge Deep Posted January 25, 2007 Share Posted January 25, 2007 I havent noticed a reduction in noise particularly. The only thing I've noticed is that when you throttle off in gear, the truck will coast a little further before the speed starts to drop off. I haven't done enough distance to notice fuel consumption yet... Quote Link to comment Share on other sites More sharing options...
TooTallMike Posted January 25, 2007 Author Share Posted January 25, 2007 For the wrecker it's a combination of fuel economy, wear, vibration, noise and a plain old engineering challenge. It also beats dropping the front prop on my head again when installing it. Incidentally I think I also read that you should machine out the dummy tube to allow for a bronze tube to 'carry' the halfshaft, otherwise it would be rotating against machined cast steel. On split-axle GMCs & WLFs there is a retaining bolt which holds the end of the halfshaft tight against the inner face of the drive flange, thus locating the UJ correctly in the housing (ie. in vertical alignment with the kingpins) for the purposes of correct operation while steering. How is this dealt with in the dummy flanges since the flange and halfshaft will rotate independently? My feeling is that the lateral location of the UJ is less important when it is not being driven either by the road wheels or the transfer box, since in ideal (ie. friction-less) cirumstances it would not be rotating and would only move a small amount when steering. Sorry if this is getting too technical but I don't want to inadvertently cause more wear than I'm trying to avoid! Quote Link to comment Share on other sites More sharing options...
Karoshi Posted January 25, 2007 Share Posted January 25, 2007 Tootallmike, thanks for the thought. Yes I'm still interested in split drive flanges, perhaps you can drop me an e-mail to Belringer @ ntlworld.com . I had considered machining some hubs out, but after experimenting I'm not totally convinced that a "real" saving is to be had. It may well lessen steering problems and reduce the noise a little, but is the hassle worth it, when you actually do get stuck ! If like Dr deuce I was doing high milage it might be worth it, but by the time you've fitted bigger tyres, larger engine and an auto box , you might as well have started with a different vehicle in the first place ! I like my jimmy just the way she is,....... Vanilla. Quote Link to comment Share on other sites More sharing options...
Enigma Posted January 25, 2007 Share Posted January 25, 2007 Tootallmike, thanks for the thought. Yes I'm still interested in split drive flanges, perhaps you can drop me an e-mail to Belringer @ ntlworld.com . I had considered machining some hubs out, but after experimenting I'm not totally convinced that a "real" saving is to be had. It may well lessen steering problems and reduce the noise a little, but is the hassle worth it, when you actually do get stuck ! If like Dr deuce I was doing high milage it might be worth it, but by the time you've fitted bigger tyres, larger engine and an auto box , you might as well have started with a different vehicle in the first place ! I like my jimmy just the way she is,....... Vanilla. You can machine the hubs...just make sure you've got a good set in reserve with you in case you get stuck! Quote Link to comment Share on other sites More sharing options...
awg Posted January 25, 2007 Share Posted January 25, 2007 please correct me if i am wrong. You can make up dummy flanges without machining anything. It is only the splined hub that causes the axles to rotate Once that is removed the front axles do not rotate at all, UNLESS the front axle is engaged via the transfer case. I made dummy flages out of flat aluminium and simply attached them using only 4 bolts ( i only drilled 4 holes in my dummy hubs ) The axles simply sit there. The reason I did this is my front inner oil seals were leaking badly, causing dif oil to foul the brakes. They do not leak once this has been done. I subsequently put the hubs back on, once the problem was rectified The info I used to do this was obtained over the 'net, as per dr deuce, i think. A search on CCKW should reveal regards tony Quote Link to comment Share on other sites More sharing options...
Enigma Posted January 26, 2007 Share Posted January 26, 2007 please correct me if i am wrong. You can make up dummy flanges without machining anything. It is only the splined hub that causes the axles to rotate Once that is removed the front axles do not rotate at all, UNLESS the front axle is engaged via the transfer case. I made dummy flages out of flat aluminium and simply attached them using only 4 bolts ( i only drilled 4 holes in my dummy hubs ) The axles simply sit there. The reason I did this is my front inner oil seals were leaking badly, causing dif oil to foul the brakes. They do not leak once this has been done. I subsequently put the hubs back on, once the problem was rectified The info I used to do this was obtained over the 'net, as per dr deuce, i think. A search on CCKW should reveal regards tony Yep, I did the same on my Dodge WC 21, don't forget to take the original hubs with you though! [attachment deleted by admin] Quote Link to comment Share on other sites More sharing options...
TooTallMike Posted January 26, 2007 Author Share Posted January 26, 2007 Tony/Enigma, That's a really good point and I hadn't considered it at all. Looking at the cut-away diagrams, my only concern is that there would be nothing to support the end of the halfshaft. In the case of GMC split and banjo axles, there is a 'steering knuckle bushing' (part AI on p183 & part A on p213 of TM 0-1801) which goes some way to supporting the shaft, but it is designed to be supported from the end too, not float on this bushing. Again, this may not be a problem while front drive isn't engaged. Karoshi - I can't comment on your GMC but the WLF is a different vehicle with the front prop. removed so for me this is a worthwhile project. Mail sent. Quote Link to comment Share on other sites More sharing options...
awg Posted January 27, 2007 Share Posted January 27, 2007 Just to clarify the dummy hub construction. I used several thicknesses of 3/8 inch aluminium plate to make mine, they can be glued together, there is virtually no stress on this area. If you want to ensure that your axle end does not flop about at all, you can cut & recess the inside piece of alum to collar the axle end. One side needs this to be done anyway, as the axle pokes out further. Only drill 4 holes are needed, not 8, for easier fitment Yes!, make sure your hubs are with you in the truck. I forgot and took my truck down a very steep dirt track, and needed to self-winch myself out, to the amazement of onlookers. If I am correct in my memory, the informant stated these can be made of wood! I made up templates using 5 ply timber, which was a good idea I dont like to murder perfectly good parts. I believe Vehicles of Victory have them advertised for $160 Quote Link to comment Share on other sites More sharing options...
TooTallMike Posted January 29, 2007 Author Share Posted January 29, 2007 Once again I'm very pleased I consulted such a wise audience! I'll turn up some some wooden ones to test fit and then make real ones once I'm happy with the design. For my own satisfaction I'll try to follow the original external profile (and in my case I will need to drill all 8 holes as my drive flanges are mounted on studs). I think I'll also look at incorporating some form of bronze bush inside to carry the end of the shaft. Agreed it is much better than destroying genuine parts. I'll post photos at a later date. Many thanks - Mike. Quote Link to comment Share on other sites More sharing options...
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