Ocheye Posted April 29, 2022 Report Share Posted April 29, 2022 Hi all I need to pick some brains. I've just returned from a short motoring holiday in the 4 (approx 300 miles) and the old fella has slipped something. Here's what happened. Wednesday morning start and there was a strange light whirring noise once the car was fired up. Sounded a bit like the heater fan but that was switched off. Checked the fan belt and looked around for a stray leaf or stick but nothing to be seen. It disappeared once we were under way then reappeared for a few seconds. As soon as we were warmed up it went away for good. Tootling along in traffic was fine but when I put my foot down it felt as if something was slipping very slightly as though I'd accidentally depressed the clutch pedal a touch. I drove very gently and parked up to embark on a boat trip to the Farne Islands. Drove gently back to our B and B after. Over some fairly steep hills taking it very gingerly. When we got back there was a bit of a smell and some smoke/vapour coming from the gearbox tunnel area. Thursday we had to plan our journey home to Carlisle avoiding going over the Cheviots or heading down the A1 to Newcastle so it was a gentle trip the long way round through the Scottish Borders. By taking it very gently I was able to avoid too much slippage and we arrived home last night. I'm unsure whether or not the clutch itself is slipping or something in the J type overdrive which otherwise is functioning perfectly and was a godsend on the return trip. I'd hate to change the clutch only to find that it is an overdrive issue. My head is telling me that it is the clutch (the slipping symptoms and the mystery whirring sound), my lack of engineering nous is ringing alternative warning bells or it may just be paranoia. BTW if you were driving one of the 4 TRs I saw between Langholm and Hawick, I hope you are having a less traumatic trip. Thoughts anyone Andy Quote Link to post Share on other sites
Rob Salisbury Posted April 29, 2022 Report Share Posted April 29, 2022 Hi Andy, Well, from your description of the smoke/vapour and smell (clutch slip is fairly distinctive rather like the smell of cooked brakes) sounds to me like clutch slip, but either way the gearbox/overdrive has to come out and then it would be obvious if the clutch was failing (polished rivet heads, little or no clutch lining etc), and if the clutch is OK, well you could have a look inside the overdrive, but best taken to a specialist. Cheers Rob Quote Link to post Share on other sites
Ocheye Posted April 29, 2022 Author Report Share Posted April 29, 2022 (edited) Thanks Rob Pretty much my thoughts. I won't be messing with the overdrive myself unless it is something obvious. It functions well and smoothly so I'm hoping it is okay. Any idea what would cause the whirring noise (a bit like a fan blade kissing something lightly)? Andy Edited April 29, 2022 by Ocheye Quote Link to post Share on other sites
stuart Posted April 29, 2022 Report Share Posted April 29, 2022 1 hour ago, Ocheye said: Any idea what would cause the whirring noise (a bit like a fan blade kissing something lightly)? Andy When the plate gets worn far enough it is basically fan shaped metal under the material. Stuart. Quote Link to post Share on other sites
Ocheye Posted April 29, 2022 Author Report Share Posted April 29, 2022 You could be right Stuart but it only did it when I first started up, in neutral. It then did it once briefly after about half a mile. Since then it has done about 100 miles on varied roads and no noise, just a hint of slipping. Andy Quote Link to post Share on other sites
Charlie D Posted April 29, 2022 Report Share Posted April 29, 2022 Andy, Can you tell a worn clutch by feeling how soon pressing the clutch pedal causes the clutch to dis-engage? If it were badly worn I would guess that the slightest press on the pedal would cause it to slip. Have you tried that? Charlie. Quote Link to post Share on other sites
Drewmotty Posted April 29, 2022 Report Share Posted April 29, 2022 How does the clutch feel. I’m not discounting a slipping clutch but thinking of what else could cause it to slip. How about a sticking clutch slave or release carrier sticking on the gearbox nose. Noise could be the release bearing working hard and getting hot. In the overdrive the uni clutch would have to fail and the cone clutch wear to get slippage. I have known an overdrive with destroyed uni clutch to start slipping. The owner didn’t know that the uni clutch had gone because the car had always been like that! If the box is coming out I’d get it and the overdrive checked out anyway…funds permitting. Quote Link to post Share on other sites
Ocheye Posted April 29, 2022 Author Report Share Posted April 29, 2022 44 minutes ago, Charlie D said: Andy, Can you tell a worn clutch by feeling how soon pressing the clutch pedal causes the clutch to dis-engage? If it were badly worn I would guess that the slightest press on the pedal would cause it to slip. Have you tried that? Charlie. Maybe I should try it the other way and see how far the pedal needs to come up before it engages Andy Quote Link to post Share on other sites
Ocheye Posted April 29, 2022 Author Report Share Posted April 29, 2022 (edited) 25 minutes ago, Drewmotty said: How does the clutch feel. I’m not discounting a slipping clutch but thinking of what else could cause it to slip. How about a sticking clutch slave or release carrier sticking on the gearbox nose. Noise could be the release bearing working hard and getting hot. In the overdrive the uni clutch would have to fail and the cone clutch wear to get slippage. I have known an overdrive with destroyed uni clutch to start slipping. The owner didn’t know that the uni clutch had gone because the car had always been like that! If the box is coming out I’d get it and the overdrive checked out anyway…funds permitting. I hadn't noticed anything odd about how the clutch felt though these things can creep up gradually. Would letting the clutch out with the footbrake hard down tell me anything? I would assume that if it doesn't stall then the clutch is slipping. Andy Edited April 29, 2022 by Ocheye Quote Link to post Share on other sites
Lebro Posted April 29, 2022 Report Share Posted April 29, 2022 I don't know a bout a J type, but an A type overdrive cannot slip, as there is a unidirectional clutch, which will transmit drive (1:1 ratio) even if all linings are worn out. Bob Quote Link to post Share on other sites
John L Posted April 29, 2022 Report Share Posted April 29, 2022 Isnt it worth checking the clutch lever free play first of all. It will depend if you have a fixed clutch adjustment rod with the spring, or a self adjusting system without the external spring. John Quote Link to post Share on other sites
stuart Posted April 29, 2022 Report Share Posted April 29, 2022 J type overdrives can slip if abused. Stuart. Quote Link to post Share on other sites
Ocheye Posted April 29, 2022 Author Report Share Posted April 29, 2022 21 minutes ago, stuart said: J type overdrives can slip if abused. Stuart. Mine gets used a lot but I hope I haven't abused it Andy Quote Link to post Share on other sites
Ocheye Posted April 29, 2022 Author Report Share Posted April 29, 2022 23 minutes ago, John L said: Isnt it worth checking the clutch lever free play first of all. It will depend if you have a fixed clutch adjustment rod with the spring, or a self adjusting system without the external spring. John If by 'free play' you mean the slackness on the pedal, it is about 1" or maybe a bit less. I was told that they were all self adjusting but can't get under to see. The slave cylinder reservoir hasn't lost any fluid Andy Quote Link to post Share on other sites
John L Posted April 29, 2022 Report Share Posted April 29, 2022 Its the lever underneath on the slave cylinder you need the free play on, the pedal will always have a bit of play due to wear in the lever and the pin. John Quote Link to post Share on other sites
Drewmotty Posted April 29, 2022 Report Share Posted April 29, 2022 6 hours ago, Lebro said: I don't know a bout a J type, but an A type overdrive cannot slip, as there is a unidirectional clutch, which will transmit drive (1:1 ratio) even if all linings are worn out. Bob I stripped one which had a grenaded uni clutch and the cone clutch had worn causing it to slip. The owner had always eased the throttle when changing in or out of overdrive so that it didn’t over rev when between in and out. As it had always been like that in his ownership he thought it normal. Quote Link to post Share on other sites
Ocheye Posted April 30, 2022 Author Report Share Posted April 30, 2022 15 hours ago, John L said: Its the lever underneath on the slave cylinder you need the free play on, the pedal will always have a bit of play due to wear in the lever and the pin. John Thanks Quote Link to post Share on other sites
Ocheye Posted April 30, 2022 Author Report Share Posted April 30, 2022 13 hours ago, Drewmotty said: I stripped one which had a grenaded uni clutch and the cone clutch had worn causing it to slip. The owner had always eased the throttle when changing in or out of overdrive so that it didn’t over rev when between in and out. As it had always been like that in his ownership he thought it normal. Fingers crossed that it isn't the overdrive Andy Quote Link to post Share on other sites
Ocheye Posted May 1, 2022 Author Report Share Posted May 1, 2022 I have just read this thread elsewhere about a J type overdrive slipping which is a little alarming. https://www.clubtriumph.co.uk/forums/topic/1660-clutch-or-od-slipping/ I'm going to have to take the 4 out again and see what I can induce (or indeed deduce!). Any suggestions as to a logical process of testing. Finding an empty road on Bank Holiday Monday could be tricky. Andy Quote Link to post Share on other sites
rcreweread Posted May 1, 2022 Report Share Posted May 1, 2022 Andy - hate be be a doom monger but as soon as I read your original post, I immediately thought the OD was likely to be the culprit. If it was the clutch, I would expect that to be a more continuous and progressive slipping. I have experienced whirring noises like you initially described on a defective overdrive. Rebuild time I'm afraid - try Pete Cox Sportscars or alternatively give them a call to discuss. Might be an idea to have your gearbox checked over and upgraded at the same time Cheers Rich Quote Link to post Share on other sites
Ocheye Posted May 2, 2022 Author Report Share Posted May 2, 2022 17 hours ago, rcreweread said: Andy - hate be be a doom monger but as soon as I read your original post, I immediately thought the OD was likely to be the culprit. If it was the clutch, I would expect that to be a more continuous and progressive slipping. I have experienced whirring noises like you initially described on a defective overdrive. Rebuild time I'm afraid - try Pete Cox Sportscars or alternatively give them a call to discuss. Might be an idea to have your gearbox checked over and upgraded at the same time Cheers Rich Thanks Rich I hope you're wrong. I'm going to try some tests today like releasing the clutch while holding down footbrake, seeing if I get any slip if I don't engage overdrive at all, seeing if there is any difference whether hot or cold. If it is the unidirectional clutch in the overdrive maybe changing the rollers alone would suffice although that would be subject to inspection. That would save a heck of a lot of cash but would be a pain if I needed to strip it down twice Andy Quote Link to post Share on other sites
Ocheye Posted May 2, 2022 Author Report Share Posted May 2, 2022 (edited) Well, I've been out on a test run and I'm pretty sure that the clutch is ok. It instantly stalls when letting the clutch out in 1st and reverse before and after a run. No probs at all in normal drive but I failed to induce slipping when I tried putting it into overdrive though I was a bit limited by traffic and the only hills being in a 30 mph zone. I'm not sure how long it takes for the gearbox oil to get up to temperature. My concern now is whether I am likely to do any damage if I avoid overdrive or whether it makes any difference. I have a charity run coming up in 9 days and taking part in the TS2 convoy with the Cumbria branch shortly Andy Edited May 2, 2022 by Ocheye Quote Link to post Share on other sites
peter clarke Posted May 3, 2022 Report Share Posted May 3, 2022 Both J and A type overdrives can slip. They both have a double faced cone clutch inside which is held in the ordinary drive position by the 8 internal springs and in the overdrive position by the oil pressure acting on the pistons which slides the cone to act on the other face. Weak springs/insufficient oil pressure will cause slippage but a very rare occurrence with either types. There are internal "o" rings which can harden due to heat of oil in gearbox over a long time allowing them to pass oil resulting in reduced pressure. Quote Link to post Share on other sites
peter clarke Posted May 3, 2022 Report Share Posted May 3, 2022 correction the 8 springs are in the a type Quote Link to post Share on other sites
Hamish Posted May 3, 2022 Report Share Posted May 3, 2022 If you have ruled out the clutch and oil levels are ok. time to at least talk to https://petecoxsportscars.co.uk/testimonials Pete or Tom will talk you through the “what if” they can do the work too. They are my go too people for gearbox, OD’s, axles etc. Quote Link to post Share on other sites
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