Jo Neyskens Posted June 24, 2020 Report Share Posted June 24, 2020 Hi all, I have a question about my gearbox from my TR4 (1962). Does anyone know why my gearbox is harder to switch in hot weather? It's harder to get into gear. Sometimes from three to four a little crack. Not Always. Just that it's not completely synced. In the spring I never had this before. And only if he's been riding hot. The next day everything is back to normal Quote Link to post Share on other sites
rcreweread Posted June 24, 2020 Report Share Posted June 24, 2020 Jo - almost certainly to do with the oil you are using getting thinner as it gets hotter - what oil are you using and I'm assuming it's a non overdrive gearbox? Whatever, drain the oil and refill with new oil ( if it's old) and/or a thicker oil . Ultimately your synchros are probably a little worn, but so long as you recognise that and take your time when changing gear in the suspect ratios, you should be fine Cheers Rich Quote Link to post Share on other sites
stillp Posted June 24, 2020 Report Share Posted June 24, 2020 +1 Pete Quote Link to post Share on other sites
Jo Neyskens Posted June 24, 2020 Author Report Share Posted June 24, 2020 2 hours ago, rcreweread said: Jo - almost certainly to do with the oil you are using getting thinner as it gets hotter - what oil are you using and I'm assuming it's a non overdrive gearbox? Whatever, drain the oil and refill with new oil ( if it's old) and/or a thicker oil . Ultimately your synchros are probably a little worn, but so long as you recognise that and take your time when changing gear in the suspect ratios, you should be fine Cheers Rich Hi, I am using 80W90 GL5. It is a non overdrive gearbox. The oil is from august 2019. Thanks for the info!! Quote Link to post Share on other sites
peejay4A Posted June 24, 2020 Report Share Posted June 24, 2020 (edited) If I were you I’d drain it and replace with GL4. GL5 additives might be attacking the synchromesh teeth. That’s the opinion of many in the past. I’m no oil engineer though. Edited June 24, 2020 by peejay4A Quote Link to post Share on other sites
Jo Neyskens Posted June 24, 2020 Author Report Share Posted June 24, 2020 14 minutes ago, peejay4A said: If I were you I’d drain it and replace with GL4. GL5 additives might be attacking the synchromesh teeth. That’s the opinion of many in the past. I’m no oil engineer though. My mistake, i just checked the bill. It's indeed 80w90 GL 4. They used 80w90 gl5 for the diff Quote Link to post Share on other sites
stillp Posted June 24, 2020 Report Share Posted June 24, 2020 (edited) I had 80W90GL4 in the gearbox and o/d for many years. Just changed to Penrite GB40 and the gearchange is a lot nicer. Pete Edited June 24, 2020 by stillp Finger trouble Quote Link to post Share on other sites
ctc77965o Posted June 24, 2020 Report Share Posted June 24, 2020 is your clutch working properly? Clutch not disengaging fully when hot due to hydraulic limitation would explain your symptoms. Quote Link to post Share on other sites
ctc77965o Posted June 24, 2020 Report Share Posted June 24, 2020 The clutch master cylinder has a small rubber seal that blocks the reservoir feed when the pedal is pressed... if that little seal degrades then it leaks more when soft/hot...meaning that as you push the clutch some fluid flows back to the reservoir...so less fluid goes to slave cylinder...slave moves less...clutch doesnt disengage...gears difficult to select. When stationary (engine running) can you select reverse without crunching when hot? if not then gearbox is not properly disengaged. Quote Link to post Share on other sites
Geko Posted June 25, 2020 Report Share Posted June 25, 2020 (edited) On 6/25/2020 at 5:43 AM, ctc77965o said: The clutch master cylinder has a small rubber seal that blocks the reservoir feed when the pedal is pressed... if that little seal degrades then it leaks more when soft/hot...meaning that as you push the clutch some fluid flows back to the reservoir...so less fluid goes to slave cylinder...slave moves less...clutch doesnt disengage...gears difficult to select. When stationary (engine running) can you select reverse without crunching when hot? if not then gearbox is not properly disengaged. Had the same symptoms in reverse gear on the MGTF for a few weeks but didn't bother, then the master failed completely. Opened the reservoir: full of black fluid. Rubber seals had disintegrated, yet at the slave cylinder fluid was clear. Might worth taking a look at the fluid colour at master cylinder to confirm/discard. Edited June 26, 2020 by Geko Quote Link to post Share on other sites
peejay4A Posted June 25, 2020 Report Share Posted June 25, 2020 (edited) I’ve used ep 80/90 then Penrite 40 then ep 80/90. No perceptible difference. Edited June 25, 2020 by peejay4A Quote Link to post Share on other sites
Lebro Posted June 25, 2020 Report Share Posted June 25, 2020 I have used 20W50, the Penrite G40 in my O/D box, no noticable difference Bob. Quote Link to post Share on other sites
BlueTR3A-5EKT Posted June 25, 2020 Report Share Posted June 25, 2020 (edited) 17 hours ago, Jo Neyskens said: My mistake, i just checked the bill. It's indeed 80w90 GL 4. They used 80w90 gl5 for the diff There are yellow metal thrust washers behind the sun & planet gears in the standard differential so GL5 spec may not be suitable. Cheers Peter W Edited June 25, 2020 by BlueTR3A-5EKT Quote Link to post Share on other sites
signalredshaker Posted June 25, 2020 Report Share Posted June 25, 2020 14 hours ago, ctc77965o said: is your clutch working properly? Clutch not disengaging fully when hot due to hydraulic limitation would explain your symptoms. +1 James Quote Link to post Share on other sites
Andy Moltu Posted June 25, 2020 Report Share Posted June 25, 2020 Does the clutch need bleeding. Hot weather would mean any air in the clutch hydraulic system would expand and thus require more compressiong before the lever is moved? Quote Link to post Share on other sites
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