Sierra Type IRS advice wanted
Discussion
My Marcos has a 7" Sierra-based IRS and has started clacking noises on roundabouts which sounds like a CV, so I checked the drive shafts and noticed one moves with end float, one does not. I went to the local kit car place and said I had a problem as one shaft had end float - and he said they should have end float - the one without end float has the problem. The IRS is fully rose jointed so I can adjust the hub to diff distance, or I might need to move the diff across a little (it is due to come out anyway to fit a LSD).
Can anyone confirm that end float is normal, as I would have expected the shafts to be fixed at one end and floating at the other ?
I am just about to crawl under the beast to try and locate the problem, so any advice welcome.
Can anyone confirm that end float is normal, as I would have expected the shafts to be fixed at one end and floating at the other ?
I am just about to crawl under the beast to try and locate the problem, so any advice welcome.
Lovely looking car.
Are you using the tripode(sp?) type shafts? The other type have six torx bolts around each CV joint.
If you grab the drive shaft itself, between the two CV joints, then it should be possible to move it along the axis of the shaft. Shouldn't require much force if both CV joints are working correctly. The working one will probably move easily as a comparison. You may need the wheel off the ground, but I don't think so.
Are the CV joints properly lubricated, or not been touched since they left the Ford factory? If they look healthily greased inside the rubber boot, there could be a another problem...
To me, that seems like a lot of torque going through a 7" diff and tripode drive shafts. If you have sticky warm rear tyres and give it some boot in 1st gear, you might just be over stressing the CV joints causing them to fail prematurely. You can argue that the tyres let go sooner than they will in a heavier Sierra, and so it should all be fine. However, modern tyre technology could well change that. Its tricky. You could stick with the tripode shafts and 7" diff, and may well be fine, but it would be very annoying if after getting the new diff in there to find it chews up another CV joint.
Its a non-trivial amount of extra weight, but you might want to consider the Loboro (again sp?) Cosworth (and also shared with the Sapphire) type drive shafts. Don't think they will fit the 7" diff, so you would also need the Cossie 7.5" inch diff to go with them. Assuming there's room for a 7.5" in the gap. If you know what ratio you are after, I can probably give some pointers on which cars had what fitted.
Out of interest, what ratio diff do you have now? Going for the same with the the LSD? Which type is the new diff? 7" or 7.5"? Cossie viscous, ATB, etc?
I've have a little too much experience with the various types of Sierra diff, while collecting parts for my current 3.36 ratio 7.5" ATB diff, and its predecessors. Happy to pass on any of my collected knowledge on the subject.
ETA: I'd check with someone with a similar or preferably higher torque car to see which drive shafts and diff they use. The loboro shafts and 7.5" diff might be over engineering for no reason, but I do recall being advised to go with the bigger ones on my V8 Rush. Was over a decade ago, so don't quote me on it!
Are you using the tripode(sp?) type shafts? The other type have six torx bolts around each CV joint.
If you grab the drive shaft itself, between the two CV joints, then it should be possible to move it along the axis of the shaft. Shouldn't require much force if both CV joints are working correctly. The working one will probably move easily as a comparison. You may need the wheel off the ground, but I don't think so.
Are the CV joints properly lubricated, or not been touched since they left the Ford factory? If they look healthily greased inside the rubber boot, there could be a another problem...
To me, that seems like a lot of torque going through a 7" diff and tripode drive shafts. If you have sticky warm rear tyres and give it some boot in 1st gear, you might just be over stressing the CV joints causing them to fail prematurely. You can argue that the tyres let go sooner than they will in a heavier Sierra, and so it should all be fine. However, modern tyre technology could well change that. Its tricky. You could stick with the tripode shafts and 7" diff, and may well be fine, but it would be very annoying if after getting the new diff in there to find it chews up another CV joint.
Its a non-trivial amount of extra weight, but you might want to consider the Loboro (again sp?) Cosworth (and also shared with the Sapphire) type drive shafts. Don't think they will fit the 7" diff, so you would also need the Cossie 7.5" inch diff to go with them. Assuming there's room for a 7.5" in the gap. If you know what ratio you are after, I can probably give some pointers on which cars had what fitted.
Out of interest, what ratio diff do you have now? Going for the same with the the LSD? Which type is the new diff? 7" or 7.5"? Cossie viscous, ATB, etc?
I've have a little too much experience with the various types of Sierra diff, while collecting parts for my current 3.36 ratio 7.5" ATB diff, and its predecessors. Happy to pass on any of my collected knowledge on the subject.
ETA: I'd check with someone with a similar or preferably higher torque car to see which drive shafts and diff they use. The loboro shafts and 7.5" diff might be over engineering for no reason, but I do recall being advised to go with the bigger ones on my V8 Rush. Was over a decade ago, so don't quote me on it!
Edited by Rothgo Wooft on Tuesday 27th April 00:06
Thanks for the feedback. I am still figuring out quite what I have got in the IRS department. The diff is 3.14:1, and I was hoping I could slip a viscous unit in it, as I have a supposedly serviceable one - but its no big issue. I wanted something that might gently help in the wet. I hear that these 7" diffs are good for up to 250bhp so I am on the upper limit, and there's a lot of miles on the clock, so I plan on getting it out and checked over sometime - and maybe the time has arrived. The car only weighs about 850kg, so tyres will break away at a lot less load than the Sierra. All 4 CVs were replaced by the previous owner in 2003, maybe they don't last long if you load them up - and I do enjoy the acceleration from the lights, and its doing about 4000 exciting miles a year !
Having the car up on axle stands, the boots look fine, and if I lift the hub on one side, so the shaft is straight, the shaft slides easily in and out about 1/4 to 1/2" - rotate the hub and it feels bad, there is some play and some notchiness, that side is not well. On the other side the shaft doesn't seem to budge, and feels OK in rotation, so I guess it is tight at one end, but in OK condition.
I suppose I should slide the boots off and inspect under the car, but rather than crawl around on the floor the plan is to remove the shaft that feels bad and get it on the bench - that should allow me to eliminate wheel bearing or diff bearing failure (hopefully), and discover how the damned things fit together.
Anyway, I have discovered I haven't got a 41mm impact socket so am on pause til that arrives. I was hoping the drive would just slide out of the diff, but I can't seem to turn up any drawings of the variants, so its all a journey of discovery. There are 6 Torx socket head screws visible just inboard of the rubber boot at the diff, I thought they were part of the CV assembly on the shaft. Will they need to be removed to slide it out ?
Is it worth getting Haynes manual, and if so, for what car (Granada/Sierra), and will they have exploded diagrams of the different types ?
Thx, Steve
Having the car up on axle stands, the boots look fine, and if I lift the hub on one side, so the shaft is straight, the shaft slides easily in and out about 1/4 to 1/2" - rotate the hub and it feels bad, there is some play and some notchiness, that side is not well. On the other side the shaft doesn't seem to budge, and feels OK in rotation, so I guess it is tight at one end, but in OK condition.
I suppose I should slide the boots off and inspect under the car, but rather than crawl around on the floor the plan is to remove the shaft that feels bad and get it on the bench - that should allow me to eliminate wheel bearing or diff bearing failure (hopefully), and discover how the damned things fit together.
Anyway, I have discovered I haven't got a 41mm impact socket so am on pause til that arrives. I was hoping the drive would just slide out of the diff, but I can't seem to turn up any drawings of the variants, so its all a journey of discovery. There are 6 Torx socket head screws visible just inboard of the rubber boot at the diff, I thought they were part of the CV assembly on the shaft. Will they need to be removed to slide it out ?
Is it worth getting Haynes manual, and if so, for what car (Granada/Sierra), and will they have exploded diagrams of the different types ?
Thx, Steve
The CV joints do behave exactly as you describe if the shaft is too far in or out, or if the bend is too great. If the car was OK before, the distances angles must be all be OK. My money is on a duff CV joint.
I was trying to do a 3.14 viscous diff for the Rush originally, but ended up going for 3.6 (too high) LSD first time around... Now if I'm getting the sequence of events right in my memory, I think the Ford LSD only fits the bigger casing and was never fitted to the 7" diff, but this was on someone else's advice and I never actually tried it.
Were there also six torx bolts on the inside of the rear hubs, just like the ones near the diff? There should be if they are standard shafts. If so, you just undo both sets of six bolts and the central drive shaft and two CV joints drop out as one piece. No need to undo the big hub nut. The ball bearings can pop out of the CV joint if you bend them too far and can be a bit tricky to get back in.
The Haynes Sierra book covers both types, but not in much detail. Drop the shaft & CVs out and play with it on the bench. Its all pretty obvious!
Now I didn't know the big Loboro drive shafts fitted the 7" diff. They may well do, but I remember my 7" diff having slide out drive shafts, where as the big ones have a gert circlip holding the shaft into the diff inside the diff casing. Have you measured it across the top of the diff casting where the bolts go as a 7"? If so, I wish I knew that a few years ago!
I was trying to do a 3.14 viscous diff for the Rush originally, but ended up going for 3.6 (too high) LSD first time around... Now if I'm getting the sequence of events right in my memory, I think the Ford LSD only fits the bigger casing and was never fitted to the 7" diff, but this was on someone else's advice and I never actually tried it.
Were there also six torx bolts on the inside of the rear hubs, just like the ones near the diff? There should be if they are standard shafts. If so, you just undo both sets of six bolts and the central drive shaft and two CV joints drop out as one piece. No need to undo the big hub nut. The ball bearings can pop out of the CV joint if you bend them too far and can be a bit tricky to get back in.
The Haynes Sierra book covers both types, but not in much detail. Drop the shaft & CVs out and play with it on the bench. Its all pretty obvious!
Now I didn't know the big Loboro drive shafts fitted the 7" diff. They may well do, but I remember my 7" diff having slide out drive shafts, where as the big ones have a gert circlip holding the shaft into the diff inside the diff casing. Have you measured it across the top of the diff casting where the bolts go as a 7"? If so, I wish I knew that a few years ago!
So its just the 12 Torx and off it comes - that is handy to know as I am told the 41mm nuts can get a bit tight ! This is the first car I have had with Torx - which is a pain as I am not sure just what I have got in the toolbox to tackle them. Maybe I can replace them with some HT bolts. As far as I can see the IRS drive system and the rocker covers are the only places I have them.
While there was never a 3.14:1 LSD diff, I am reliably told that the 7" LSD internals can be swapped between any 7" diff. Mine is definitely 7" but I can't get to the tag code to read off the numbers (but I can decode tag codes).
The 3.14:1 is a rare diff, there was 3.38 to 1, which might be easier to find if you don't like the common 3.62:1. On a large capacity low revving motor I would expect 3.62:1 to be too low (or is it high - depends how you are counting!).
Steve
While there was never a 3.14:1 LSD diff, I am reliably told that the 7" LSD internals can be swapped between any 7" diff. Mine is definitely 7" but I can't get to the tag code to read off the numbers (but I can decode tag codes).
The 3.14:1 is a rare diff, there was 3.38 to 1, which might be easier to find if you don't like the common 3.62:1. On a large capacity low revving motor I would expect 3.62:1 to be too low (or is it high - depends how you are counting!).
Steve
The T45 bit comes in handy if you need to take the back plate off the diff as well. Never used it for anything else.
I have bust a couple of those T45 bits over the years when they go wonky in the hole, so it might be worth ordering two while you're at it. Though your's shouldn't be too bad compared to a rusty old Sierra!
I've got some hex head bolts on mine for clearance on one of the CV joints, but find the standard torx bolts do a fine job. No chance of rounding them off, and they're made of some sturdy metal.
I believe the 3.14 ratio diffs were only fitted to the diesel Sierras, which makes sense. I'd interested to know where the 7" LSD unit comes from. I'll post some pictures of internals of a 7.5" one if I remember. It would be interesting to know if the two are compatible.
I have bust a couple of those T45 bits over the years when they go wonky in the hole, so it might be worth ordering two while you're at it. Though your's shouldn't be too bad compared to a rusty old Sierra!
I've got some hex head bolts on mine for clearance on one of the CV joints, but find the standard torx bolts do a fine job. No chance of rounding them off, and they're made of some sturdy metal.
I believe the 3.14 ratio diffs were only fitted to the diesel Sierras, which makes sense. I'd interested to know where the 7" LSD unit comes from. I'll post some pictures of internals of a 7.5" one if I remember. It would be interesting to know if the two are compatible.
All the following are LSD according to my notes (lifted from the Sierra club) - but include 7" and 7.5":
ALL 4x4 Sierra's and Granada's (2.8/9 and 2.0DOHC and Cosworth)
Most BUT not all 24v Cosworth Granada/Scorpio (upto approx 1994 are LSD, after the Scorpio 24v had traction control instead)
All RWD Cosworth Sierra (3dr, Saff, RS500)
Then you might find an LSD fitted as an option to any Sierra or Granada, but unlikely.
I think the 4x4s are 7", whereas the RWD listed above were 7.5".
There was a 7.5" 3.14:1 diff if you find a Sierra 2.8 V6 auto - but not LSD. Could be useful for a big V8 in a kit car I would have thought - might even be useful to me !
ALL 4x4 Sierra's and Granada's (2.8/9 and 2.0DOHC and Cosworth)
Most BUT not all 24v Cosworth Granada/Scorpio (upto approx 1994 are LSD, after the Scorpio 24v had traction control instead)
All RWD Cosworth Sierra (3dr, Saff, RS500)
Then you might find an LSD fitted as an option to any Sierra or Granada, but unlikely.
I think the 4x4s are 7", whereas the RWD listed above were 7.5".
There was a 7.5" 3.14:1 diff if you find a Sierra 2.8 V6 auto - but not LSD. Could be useful for a big V8 in a kit car I would have thought - might even be useful to me !
OK, dodgy shaft is off, and I still don't understand what is supposed to slide so the shaft length changes. Though both CVs are well greased one is stiff to turn to an angle, but the centre is rather sloppy on the shaft, and the other the outside loosely slides up and down with respect to the centre and it has rotary play. Nothing that a complete new shaft and CVs won't cure, though I wonder now if it is a Marcos special, i.e. an odd length.
Tomorrow the other side comes off and then Saturday try and track down a specialist.
The good news is I may at last have found the source of the slight high speed vibration that has been bugging me.
Tomorrow the other side comes off and then Saturday try and track down a specialist.
The good news is I may at last have found the source of the slight high speed vibration that has been bugging me.
Something moves lengthways. Its been two years since I had them apart, so its a bit hazy, but I think it was the CV joint itself.
The middle part can move err.. up & down in this picture. See how its sticking up because its on a table.
I remember spending some time studying the cunningness of the design.
My splined shafts were a bit slack to. I decided to live with it until I found a source of new shafts. Last I heard was that Ford Parts no longer stock them. Forgotten all about about it until just now. If you find a supplier, please let me know.
I'll measure the length of my standard shafts tomorrow and report back, if I manage to remember...
The middle part can move err.. up & down in this picture. See how its sticking up because its on a table.
I remember spending some time studying the cunningness of the design.
My splined shafts were a bit slack to. I decided to live with it until I found a source of new shafts. Last I heard was that Ford Parts no longer stock them. Forgotten all about about it until just now. If you find a supplier, please let me know.
I'll measure the length of my standard shafts tomorrow and report back, if I manage to remember...
Remember also there are 2 types of 7" LSD - an AP Suretrac - This has a habit of breaking gearboxes - the Caterham racers all swapped them out as tehy were continually breaking 2nd gear.(inside wheel spins up an on recontacting tarmac all that energy has to go somewhere)
The other is a ZF plate type. This uses a ramp and clutch mechanism to transfer drive across the axle. Great in principle, but as its designed for a heavy car with a focus on traction, the reaction of a good chassis is for teh drive to force the front of the car wide. This can be addressed by changing the ramp angles and slip ratios. Road and Race Transmissions in Shorham Kent do this, and the result is the best compromise overall.
To tell the difference between the two types look through the centre of the diff (along the driveshaft axis) where the planet gears sit. If there is one small shaft across the centre its an AP Suretrac, two shafts means its a ZF.
Finally, I used the same diff mech and casing on my car (300bhp Caterham) for 16 years with no issues. Sure I only had 200ft/lbs of torque, but they are a really heavy duty part. They are also very heavy, which is a bad thing.
The other is a ZF plate type. This uses a ramp and clutch mechanism to transfer drive across the axle. Great in principle, but as its designed for a heavy car with a focus on traction, the reaction of a good chassis is for teh drive to force the front of the car wide. This can be addressed by changing the ramp angles and slip ratios. Road and Race Transmissions in Shorham Kent do this, and the result is the best compromise overall.
To tell the difference between the two types look through the centre of the diff (along the driveshaft axis) where the planet gears sit. If there is one small shaft across the centre its an AP Suretrac, two shafts means its a ZF.
Finally, I used the same diff mech and casing on my car (300bhp Caterham) for 16 years with no issues. Sure I only had 200ft/lbs of torque, but they are a really heavy duty part. They are also very heavy, which is a bad thing.
Rothgo Wooft said:
My splined shafts were a bit slack to. I decided to live with it until I found a source of new shafts.
GB Engineering in Nantwich can make the splined shaft bit of Sierra driveshafts to whatever length you need. They made up a custom set for my Striker - shorter than standard and with splines for the lobro type joints on one end to mate with my LSD and tripode ones at the other so I could use a Sierra drum braked hub (and VW calipers / disc conversion).ETA - I've got a 7" diff with a viscous type LSD. As I understand it they were fitted to the XR Sierra variants. Cosworths had 7.5" diffs and all other models had open 7" diffs (maybe with LSD as an option). You should be able to swap the LSD unit from one diff to another, but I think you have to change something else too... Possibly the output flanges.
Edited by FlatPack on Friday 30th April 12:38
Nantwich - thats just down the road for me - excellent.
As for the 2 types of LSD for the Sierra - I think that there are lots of aftermarket types, but I suspect the production cars only had viscous (could be wrong). I see GKN list 5 different types that they make - there is lots of lovely information on the GKN Driveline website http://www.gkndriveline.com/drivelinecms/opencms/e... , look for Torque Management Devices.
I bought the viscous unit off a hill climber who wanted to swap to a mechanical unit to get more rapid action - I am after something that might help in the wet on the road, so more viscous and less vicious. It was cheap as chips, and I am assured it is fine working order, but if it doesn't quite do the job, then I will be no worse off than an open diff anyway.
As for the 2 types of LSD for the Sierra - I think that there are lots of aftermarket types, but I suspect the production cars only had viscous (could be wrong). I see GKN list 5 different types that they make - there is lots of lovely information on the GKN Driveline website http://www.gkndriveline.com/drivelinecms/opencms/e... , look for Torque Management Devices.
I bought the viscous unit off a hill climber who wanted to swap to a mechanical unit to get more rapid action - I am after something that might help in the wet on the road, so more viscous and less vicious. It was cheap as chips, and I am assured it is fine working order, but if it doesn't quite do the job, then I will be no worse off than an open diff anyway.
Rothgo Wooft said:
Something moves lengthways. Its been two years since I had them apart, so its a bit hazy, but I think it was the CV joint itself.
Greetings to a fellow Rush owner 
That's a lobro joint. They are indeed a genius bit of design IMO.
As someone above mentioned, the Xr4x4 has a 3.62 LSD, with a 7" casing. This has lobro joints as above. I know 'cos I've got one on mine
Pretty sure you can get replacement joints, don't need to change the shaft as well.
Have had a measure up and have 27mm diameter shafts with 25 splines. Same type of Lobro joints both ends - just like your photo - 100mm OD, 86mm PCD, bolt-ons. Looks like GKN Motorsports make them and have seen part no MS3K023 (or the lightweight version MS3K020). Stocked by various sporty shops with prices (so far) from £56 to £99. I think thats quite a bit more than standard joints, but hopefully they will be better able to withstand my 4.5 V8 leaning on them ! There is apparently a heavy duty MS3K038 - but I haven't found a supplier for that.
I have also found distressing tales of a range of different splines and joint types on Ford cars - 23 splines, 25 splines, 26 splines, 28 splines, different joint types, different bolt PCDs, even different shaft diameters - the Ford designers must be completely barmy. Three or four different types would surely give enough range to cover everything.
I have also found distressing tales of a range of different splines and joint types on Ford cars - 23 splines, 25 splines, 26 splines, 28 splines, different joint types, different bolt PCDs, even different shaft diameters - the Ford designers must be completely barmy. Three or four different types would surely give enough range to cover everything.
Noccer said:
I have also found distressing tales of a range of different splines and joint types on Ford cars - 23 splines, 25 splines, 26 splines, 28 splines, different joint types, different bolt PCDs, even different shaft diameters - the Ford designers must be completely barmy. Three or four different types would surely give enough range to cover everything.
Yeap I was in Ford CV joint hell for a while and that was just with Sierra bits! Ended up getting the splined shafts made up to fit the joints I have as it was easier than trying to figure out what Ford were doing.The lobro joints are very clever, but a complete nightmare if one comes apart and you want to put it back together again. They go together in two almost indistinguishable ways, one of which locks it solid and makes it virtually impossible to take it apart again to fix it.
Hi,
If it helps, a local friendly Ford Dealer let me copy all his parts microfiche. I've put together everything I've found on my website at http://www.super7thheaven.co.uk/Components. There are lots of exploded diagrams, part numbers, repair manuals etc.
Good luck !
If it helps, a local friendly Ford Dealer let me copy all his parts microfiche. I've put together everything I've found on my website at http://www.super7thheaven.co.uk/Components. There are lots of exploded diagrams, part numbers, repair manuals etc.
Good luck !
Thanks, there is a lot useful info on your website.
Although your post is about 6 months after the original, I now have the same problem on my offside drive-shaft. So I guess it is just that the CVs that were fitted weren't really man enough. Hopefully the new ones from RaceParts will last a bit longer.
Interesting that you say on your website that the 7" and 7.5" diffs are the same strength, I think the issue for me is whether the 7.5" is the only one that offers the larger bolt-on flanges and stronger CVs.
Although your post is about 6 months after the original, I now have the same problem on my offside drive-shaft. So I guess it is just that the CVs that were fitted weren't really man enough. Hopefully the new ones from RaceParts will last a bit longer.
Interesting that you say on your website that the 7" and 7.5" diffs are the same strength, I think the issue for me is whether the 7.5" is the only one that offers the larger bolt-on flanges and stronger CVs.
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