Cheesy Posted March 5, 2014 Share Posted March 5, 2014 I am slowly getting an 89 RRC working properly, now in the process of driving though traffic with an engine that kept stalling I inverted the sprag, its a pain to drive now. Anyway I have an unknown spare with an LT230. So the question is can the sprag be checked in the unknown box without taking it to bits? Secondly I assume the LT230 is a better option than the borg warner transfer case? Quote Link to comment Share on other sites More sharing options...
Boydie Posted March 5, 2014 Share Posted March 5, 2014 SPRAG ???? What is a sprag ????? Quote Link to comment Share on other sites More sharing options...
Rangy35 Posted March 5, 2014 Share Posted March 5, 2014 Yes please help, don't have a clue what n "sprag" is. Quote Link to comment Share on other sites More sharing options...
landroversforever Posted March 5, 2014 Share Posted March 5, 2014 I assume he's talking about a sprag clutch? thats the only use of the word I can think of. Quote Link to comment Share on other sites More sharing options...
dirtyninety Posted March 5, 2014 Share Posted March 5, 2014 from the ashcroft website... A common problem with all ZF 4HP22/24 boxes is the failure of the one way "sprag" clutch. Once the cams in this one way sprag clutch "flip" the unit will slip both ways resulting in the vehicle only pulling off with the shifter in position "1" not "D" and driving OK when shifted up to position 2,3 and D until you stop then you need to pull it back to "1" to start off again. It is not feasible to change this unit in each rebuild as this one part is approx £400. By disassembling the "sealed unit" we were able to examine the profile of the cams and understand how they work, from here the challenge was to find another cam from another type of autobox that would fit and had the correct profile to make the unit stronger by not allowing the cams to flip. After quite a lot of searching we found one, "re-cammed" some of these clutches and thoroughly tested them, we have not had one fail since. This is an example of how we are able to use our engineering background to understand a problem and cost effectively make the unit stronger without having to raise our prices. Quote Link to comment Share on other sites More sharing options...
Cheesy Posted March 5, 2014 Author Share Posted March 5, 2014 Woops, yes the sprag cluctch/bearing that inverts and stops drive from working Quote Link to comment Share on other sites More sharing options...
smallfry Posted March 5, 2014 Share Posted March 5, 2014 I cant believe that you lot are such dimwits......................I despair. The sprag clutch prevents the epiglottal wobbler shaft from being driven backwards, thus breaking the gangle trumpet spigot. There.......now you know. Now you really DO know everything. Just like me ! Or in simpler terms, its a freewheel device. You know if you ride a bicycle and stop pedalling, the pedals stay still and the rear wheel still turns. You can hear the clicking of the pawls or balls. Thats a sprag clutch. Sort of. Some bearing races only work one way and lock when you try to turn them backwards. Not sure how they work though, Quote Link to comment Share on other sites More sharing options...
Phil Hancock Posted March 5, 2014 Share Posted March 5, 2014 Some bearing races only work one way and lock when you try to turn them backwards. Not sure how they work though, The bearing outer has a slight cam profile in it, movement of the rollers away from the cam allows the shaft to turn, turning the shaft the other way pulls the rollers in till it jams and then the outer turns. http://www.google.co.uk/imgres?imgurl=http://www.tinyclutch.com/Portals/77644/images/rollhous.gif&imgrefurl=http://www.tinyclutch.com/roller-clutches/&h=141&w=421&tbnid=Yg4gjSRPQIUnSM:&tbnh=90&tbnw=269&zoom=1&usg=__zark6ZCFr8gU7bNQxMwAw4g-iyA%3D&docid=kEFsb_X29Hv8oM&sa=X&ei=ZJMXU_jfFaavygPHzoDoDQ&ved=0CDMQ9QEwAw Quote Link to comment Share on other sites More sharing options...
muddy Posted March 5, 2014 Share Posted March 5, 2014 Is the gangle trumpet spigot a serviceable item? Will. Quote Link to comment Share on other sites More sharing options...
zoltan Posted March 6, 2014 Share Posted March 6, 2014 Why are you getting on the guys case about the term 'sprag'? Do you do the same when someone says 'diff'? Thought not. Jeez! for a techie forum I'm really surprised to see four posters exclaiming shock and horror at the abbreviated use of a technical term. This place can be right up itself sometimes! Aaaand breathe ....... Quote Link to comment Share on other sites More sharing options...
Lewis Posted March 6, 2014 Share Posted March 6, 2014 Zoltan, read it again, there is only two posters who are asking what a sprag is. I read their posts as genuine questions, I didn't see any undercurrent of sarcasm. Chill out Quote Link to comment Share on other sites More sharing options...
Cheesy Posted March 6, 2014 Author Share Posted March 6, 2014 Well sprag might not be the most common term in the rover world but I do come across it a lot with bikes, usually in the electric start system, they die reguarly as well. Anyway from the lack of response to the original question Im guessing that it is not possible to check the one way clutch so I will have to look into a seal kit so I can pull it down and check. Quote Link to comment Share on other sites More sharing options...
smallfry Posted March 6, 2014 Share Posted March 6, 2014 Sorry Cheesy I do not know the answer to your question. I would also like to know why one would choose one transfer box over the other............................. Quote Link to comment Share on other sites More sharing options...
Mr Ian Posted March 7, 2014 Share Posted March 7, 2014 Hi Phil. The roller/cam outer is the older version found in the TF box and which CANNOT flip, ZF use a ,sprag, in place of the roller with smooth plain roller brg shells inner/outer, it's these sprags which are the Achilles heel on the ZF as they can and do flip. To answer the question no they cannot be checked in site . Regards. Ian ashcroft Quote Link to comment Share on other sites More sharing options...
Cheesy Posted March 12, 2014 Author Share Posted March 12, 2014 Hi Phil. The roller/cam outer is the older version found in the TF box and which CANNOT flip, ZF use a ,sprag, in place of the roller with smooth plain roller brg shells inner/outer, it's these sprags which are the Achilles heel on the ZF as they can and do flip. To answer the question no they cannot be checked in site . Regards. Ian ashcroft Thanks for that, I had a feeling that would be the answer Quote Link to comment Share on other sites More sharing options...
smallfry Posted March 16, 2014 Share Posted March 16, 2014 But what actually causes them to fail in the first place ? Or is it just general wear ? Quote Link to comment Share on other sites More sharing options...
Mr Ian Posted March 16, 2014 Share Posted March 16, 2014 Hi usually a combination of wear and mis use, if D is engaged from neutral with the engine in fast idle and there is some ' slop' in the drive line then the sprags are engaged suddenly and instead of wedging they will go over center 'flip'. As we found out they can be rebuilt with slightly different profile sprags but are still subject to going over center. It may be useful to know that when 1 is engaged a clutch plus the sprag clutch engage hence the ability to start in 1 when the sprag is inverted(drive is provided by the clutch only) . Hope this helps. Ian Ashcroft Quote Link to comment Share on other sites More sharing options...
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