Bob Horner

Pete - just read your comment above re Robush - I googled them before reading this thread- should have read your post first!! Bob

I wonder if the club ought to stock them - I bet they could get a better deal if buying in quantity? There's a lot of people swapped to CV joints but also an awful lot of people who presumably still have the old rotoflex system. One triumph specialist I know believes that the CV joints cause other issues re diffs etc because the rotoflex has a cushioning effect. Don't know if there is any truth in that. Any one any thoughts on that? Bob

Just thought I'd add my experiences to this. I've had to replace the radius arm brackets on my GT6 which necessitated removing the driveshaft and vertical link from the car so decided to go the whole hog and replace the slightly cracked donuts and rebush everything plus new timken bearings (rimmers). Decided to stay original so sourced some proper metalastik units. Demon Tweeks have them at £167.20 each (incl VAT)!! However, looked online and a firm called Robush Ltd https://www.robush.com/products/rotoflex-coupling/ do them. They were very helpful - cost £89.25 plus vat each (£107.10 incl VAT) plus £12.50 for next day delivery (in stock whereas Demon Tweeks say will get stock in within 7 days). just like to let people know if they are looking. You need to call or email as they don't sell online. You need to quote the part number which is 21/979/1 (there is a link to the original catalogue. Saves you £120 over the Demon Tweeks items (and probably only costs you £100 over the repro rubbish!) Bob

Hi Thanks for responses. I get the same message as Andy but I can download from ‘The Club’ section fine . Used to work from the forum - perhaps link not uprated for 2021 catalogue? Bob

It may be just me, but I used to be able to download the most recent shop catalogue and model specs but I just get an error message these days. Is it something that needs fixing? Regards Bob

Further to another post re fan controllers not working, I ran it up to temperature in the garage last night to check out what was wrong. To get my GT6 up to temperature without a fan running in the garage seemed to take forever - really reluctant to overheat. I'd say about 15 to 20 mins or more of ticking over before got anywhere near hot enough for the thermostat to open. Even then took a while for the gauge to start to creep up and the electric fan was only needed for a minute or two. Prior to taking the head off and attacking the crud around nos 5 and 6, it would boil in no time at all. One thing that I noticed was the bottom hose didn't get that hot which I assumed was because hot water didn't seem to be circulating around and into the engine at anything like the correct rate (indeed the in line temperature controller in the bottom hose wouldn't actually switch on as a result). I honestly can't believe the difference after the clean out and, as a result, from assuming the Gt6 was marginal cooling-wise due to received wisdom, I'd say it was better than the TR4 or the spitfire. Heating/ overheating is a delicate balance and therefore, small restrictions like a build up of crud upset that balance I suppose. Bob

Anyone had any issues with these? I’ve got them on my TR4, spitfire and GT6. After about 4 years one failed on my TR4. I replaced and worked ok since. Bought one for my GT6 a couple of years back and it didn’t work out of the box. Replaced without issue. However the replacement has now failed after a couple of years but not many miles. I have rewired it so it’s got an override switch (which is a must in my experience!). They are expensive but work well when they do work. Always wired via a relay. Just wondering about people’s experience before I shell out £80 for another. Bob

If you need to poke about to get water out of the drain plug there is probably a load more crud in there that you can get out with a bit of wire - or at least that was my experience. I think flushing using holts or similar didn’t work for me. Bob

I had awful problems re overheating in mk2 Gt6. I had the right cowl in place and the side valances. Checked sender, gauge etc. No change. Fitted a new aluminium rad. No change. Fitted a blower electric fan (don’t believe anyone that this sort causes issues - works brilliantly and gives loads of room). No change. Suspected the flow through the system wasn’t good through the bottom hose. Flushed with all sorts of products. There was only a dribble out of the tap at the rear of the block. In the end, took the head off, flushed head with phosphoric acid (recommended by an old hand and despite scepticism on here seamed to fizz away and work well). Then, after protecting bores, poked around and flushed block. Tons of crap at rear of block. Put it all back together. Now runs as cool as a cucumber. Even in the recent heat. No issues at all. Almost too cool! Taking off the head well worth the effort. You need to make sure everything is circulating through the block and head and the system is fine. I’ve spent ££ upgrading but happy with lighter rad and a couple of extra horses from revotec fan but could have got a cool engine with just a deep clean!! Live and learn. Bob

On someone else’s recommendation I used the later spitfire type tunnel cover on my mk2 Gt6. You’ll appreciate the extra clearance when trying to get the overdrive box in and it can’t be seen. Interestingly, my car was converted to overdrive and had not had its tunnel cut or a cover plate. I assume either the body was put onto the chassis with the overdrive gearbox in place or perhaps the gearbox and engine were installed together. You could tighten the prop shaft bolts at the gearbox end from underneath without the cover plate but it was a faff. I had to remove the overdrive for repair so cut back the tunnel and bought a cover plate at the same time. Bob

Thanks Pete for the alternative method, hopefully never need to do it again! Your method aligns the splines but presumably doesn't help get the plunger over the cam on the output shaft? I found that a problem until I held it back. On Youtube it shows a guy slamming it down on the shaft- presumably to overcome the issue of getting the plunger over the cam but if the splines aren't properly aligned that could cause a bit of damage. He did put a chamfer on the cam to help ease the plunger over it but I don't fancy filing off bits of metal unless I really need to. I'll amend my post above as just realised I didn't mention that you need to make sure the lowest part of the cam is at located at the point where the plunger sits. Bob

Johny - it’s all looked a bit knackered inner and outer friction lining but I was only there in the taking apart and having a quick look inside stage - but not sure what they do to recon. I think they replace the entire clutch (presumably they put new linings on a stock of old ones). Not sure about the springs - perhaps weakened springs lead it to slip and then break up with the friction? Although presumably a knackered inner lining will slip sooner than an outer one as the outer one is pressed up hard with hydraulic pressure as opposed to springs that may weaken over time. Bob

On another thread I raised the issue of a slipping overdrive and as a result it required a rebuild. I assumed refitting it would be a simple job but Googled to see what advice was out there in forums and YouTube. A lot of this a MG based and there are various posts about how difficult it is and one YouTube vid from US showing a bit of force used to bang it on to the back of the gearbox and stories of hours of trying etc etc. After finding it very difficult to mate the two myself was beginning to believe them. However, went back the the internet and found a couple of posts in agreement that it is a simple job if you do it properly. There are 2 main issues - Lining up the 2 sets of splines inside the overdrive and then getting the spring loaded pump plunger that operates on a cam on the gearbox output shaft over said cam. The most important thing I learnt was that the splines inside the overdrive may look aligned and some are, but not all are. You have to get a screwdriver to turn the rearmost set of splines anti clockwise until they ALL line up perfectly - not just some of them. The next tip is to use something to pull back the spring loaded plunger. I used a plastic cable tie wound around two of the overdrive units studs and tightened to pull it back. Having done all that it slid straight on apart from the width of the cable tie (1/4 inch). All I then needed to do was remove the cable tie - it slips off the spring and you can then cut and remove it. Other points; It’s recommended to use some gasket sealant and also I found it better to put the gasket on the overdrive rather than the adapter plate. That was because, having at last got it on the splines but not got the pump plunger over the cam, wiggling it made the studs on the overdrive damage the gasket on the adaptor plate (it’s only 1/2 inch away from mating at that point and the studs are just touching the adaptor plate). Once I used the cable tie method it wouldn’t have made much difference. Also, a couple of nuts need to you lift the overdrive unit away from the adaptor plate slightly to get them on - careful not to slip it up too far. I presume it can take a while if you don’t know the above tricks but eventually it will go on once you keep moving the internal splines (only anti clockwise) so hence battling for hours. I worked out how to get in on but had damaged the gasket for the reasons noted above. It meant I had to take it a apart and do it again with a fresh gasket a couple of days later. As proof it was unlikely to be a fluke, I used the same method and it took 10 mins to get it on and bolted up. Hope that helps someone else sometime or interested to hear any other approaches or experiences. Bob note above - you need to make sure the cam is at its thinnest point where the pump plunger locates so it can go over it as easily as possible. Broadly that's aligned at the bottom of the overdrive.

Just an update. Took the overdrive to ORS in Sheffield. Very helpful people. They pulled it apart on the bench whilst I was there to have a look. Clutch was indeed knackered (looked like heat damage due to slipping) but otherwise looked ok. Refurbished it for £375 plus Vat which compared to other prices seemed very reasonable. Very friendly and helpful people and just over 2 week turnaround (which they said would be the case). I’ve not put the box back in the car yet but having had them supply an A type for my TR4 (which has had serious abuse on some rally tests) and a D type on a spitfire which have both worked perfectly, I’m sure it will be a quality job. Putting the gearbox and overdrive back together was an interesting experience and I’ll post a separate thread in that in case anyone else is attempting to do same. Bob

I thought both, not just outer face - the diagram that Pete posted shows that doesn't it? Or perhaps I misunderstand what Pete wrote. With no seal between the inside of the box and the filter, it would draw air from the box, not through the filter. Just dry seal in my opinion. Regards Bob

Just to add to this topic many years later...... I've recently converted my standard Mk3 engine to run on Hs4s (using 1500 manifold and air box) and converted to cable throttle. At the same time I fitted a phoenix extractor and richer needles. Its absolutely transformed the engine - really flies. Massive improvement in performance (not checked fuel consumption yet though!). All pretty simple to do bar getting the accelerator linkage in the right place. I did see an article from back in the day where someone tested a similar set up done as a factory kit and they were impressed. It previously ran on Hs2s (which were rebuilt so improvement not to do with worn carbs being replaced) but using a standard exhaust manifold. All pretty reversible bar the cable throttle as had to cut the original pedal to get it out. However, a mk4 inlet manifold could be used if swapping back to Hs2s. Bob

I’ve just measured the length of the gearbox casing from the bell housing to the edge that meets the overdrive.. This is exactly the same for the std gearbox as the modded one. Thus the only thing that can lengthen it is the length of the j type compared to the d type. My understanding is that this is the same because with a bit of machining you can fit a jtype,to a std Gt6 gearbox?

Thanks for all the responses. Does anyone know the overall length of the standard gearbox plus overdrive so I can measure and compare? Bob

Hi all Further to my thread re slipping overdrive, I picked up a recon overdrive box off EBay. The seller said it was from a mk1 Gt6 and said it had been uprated byFitchetts 2 years ago. I thought it would be worth swapping for my current box and overdrive. Anyway, I spotted it was a J type rather than D type and I assumed the overdrive was the uprated bit but it seems it is a dolomite three rail as when I got it home, the spline is different and the number on the case suggests it’s from a 1850. What clutch plate will I need to fit it? Is it as simple as that? Bob

Dave has kindly got back to me - thinks its the Uni directional clutch so looks like a rebuild. At least the tunnel is already off! Will pull out the whole gearbox this week. I've asked Dave for a price. I see paddocks do one for £395 plus exchange surcharge. Anyone any experience of their exchange units? I'm in Yorkshire so spoke to ORS in Sheffield- I've used them twice before for gearboxes and overdrives but 2 week wait minimum ( and slightly more expensive by £50 plus VAT). Bob

Yes, Colin, that little bastard! More thoughtful approach needed next time. Agree, heat might have helped.

Mine weren’t from the biggest supplier but one of the ones I’ve found generally to be pretty reliable and good value. Only had a couple of issues previously. They had an inner nylon core and an outer rubber sleeve. If I had my time again I would have separated them inserted the outer and then chamfered one end of the nylon core and tapped it home. Unfortunately I got carried away with pushing it home before I realised what I had done to the outer column. Live and learn. Done loads of suspension bushes with no issues but this defeated me! Bob

Just tried to fit some uprated steering column bushes - play in column. Way too tight. Usual crap. Ended up bending column. Just posted to warn others not to make the same mistake! Seems another case of dodgy parts that don’t fit - even when you pay extra for the “‘uprated” version. Bob

Well, assumed must be O/d issue rather than main clutch if no slip when overdrive engaged?

Update. Disconnected electrics still had symptoms. I’ve taken out the tunnel now (forgot what a git of a job this is compared to a mk3 spitfire). Anyway, checked the throw of the solenoid and then removed cap nut etc to ensure all ok. Unfortunately, still seems to be slipping when not in O/d.. Unless anyone has anyone has any other bright ideas looks like it’s a recon O/D. If that’s the case, can I swap out the o/d with the gear box in situ? I had a vibration as well so removed prop to find it was out of phase by 90 degrees. Sorting that has got rid of the vibration. I wonder why it was set 90 degrees out on the first place?