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1970 TR6 cylinder head bolts
#758260 12/05/18 9:12 pm
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Hi - I'm a new user on this forum and this is probably going to sound like a silly question....I am trying to doing some work on the top end of my 1970 TR6R but I can't even get two of the central bolts (that go through the rocker covers into the cylinder head) off as the main part of the frame obstructs them. The two on the other side are fine. Is there a special way of removing these two without taking the engine out of the frame? Any suggestions appreciated!

Steve

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Re: 1970 TR6 cylinder head bolts
Steve Guildford #758284 12/05/18 10:51 pm
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I have a 1970 tr6r also and had the same problem Loosened all motor mounts and engine moved to one side to loosen bolts. I believe lower engine spacers might have been left off, just a guess

Re: 1970 TR6 cylinder head bolts
russrudolph #758359 12/06/18 3:28 pm
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Hi Russ, many thanks for quick response. Will check that out when I get home - it sounds plausible. I have looked on line and see that you can buy spacers so may invest in one or two of those....although not sure if that then affects the way the sprockets line up.


Re: 1970 TR6 cylinder head bolts
Steve Guildford #758368 12/06/18 4:45 pm
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Russ is talking about the spacers under the engine that are supposed to be there. I wouldn't add any extra ones. There should be spacers on the head steady, too. I don't know if it will make a difference to whether the head bolt will pass the top tube. The spacers were missing on mine originally but to fit them I had to move the lower frame tubes out to their original distance apart to get the spacers in. When the lower mount was done up by the previous owner the tubes had bent in a bit.

I used bit of threaded bar and a couple of nuts for this when the engine was out.

My head bolts scrape by the top tube on one side as I remember but I don't think that the spacers made any difference to this. I was more concerned about the gearbox drain plug being obscured by the bent in lower tube.

I don't remember what the chain alignment was like without the spacers but with them it seems fine.

If the spacers are in place then just do what Russ said and loosen all the engine mounting bolts while you fit the head bolts and forget about it.



Dave

Last edited by dave jones; 12/06/18 4:48 pm.
Re: 1970 TR6 cylinder head bolts
Steve Guildford #758372 12/06/18 6:35 pm
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Thanks Dave, really helpful. I’ll have a look to see what I’ve got and take it from there. I may be back at some point though...
Steve

Re: 1970 TR6 cylinder head bolts
Steve Guildford #758833 12/10/18 11:09 pm
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This is a common problem and if you remove all the head bolts inc the smaller nuts n bolts from the r/cover you can then tilt the r/box enough to remove the offending bolts.

Re: 1970 TR6 cylinder head bolts
Steve Guildford #759925 12/20/18 9:41 pm
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Hi Chainreaction - just seen this as the bike has been on the back burner but this looks like it's worth trying as a simple solution. Hope it works!


Re: 1970 TR6 cylinder head bolts
Steve Guildford #759940 12/20/18 11:52 pm
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Hi Steve, I think this is normal. On the '69 Bonnie the bolts wouldn't come past top tube. As was stated after the other bolts were loosened they could come out.

However, going back together we left all motor mount bolts & the motor can tilt just enough to get bolts by frame. I expect the '70 might be a little easier to tilt as the front mount plates can be removed. Of course the rear side plates must be loosened also.
Don


1973 Tiger 750
Re: 1970 TR6 cylinder head bolts
Steve Guildford #759976 12/21/18 2:25 pm
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Can't say I've ever had a problem with my '70 Bonneville. I just wiggle them until they come out. Same goes with reinstalling them. I don't understand the need to loosen the motor mounts unless there is another fault with the bike.

Bruce


1937 Ariel Red Hunter 500
1970 Triumph Bonneville

Making the scene with the gasoline
Re: 1970 TR6 cylinder head bolts
Steve Guildford #760025 12/21/18 10:06 pm
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Hi Bruce, How do we account for the different experience? I had head off '67 Bonnie & the bolts came out fine. I was surprised on the '69 encountering difficulty. Since I've seen difficulty on a few other bikes.

I ponder these things for some crazy reason. Are some tubes fatter, or some head holes larger ? Seems every bike I work on has a new something that teaches me about how odd or should I say "interesting" Triumphs can be.


I have much more experience on OIF bikes as that is mostly what we rode in the early 70s. Many of the dry frame bikes already had the life rung out of them at the time so we bought new or near new. Back then we thought OIF were great.
Don


1973 Tiger 750
Re: 1970 TR6 cylinder head bolts
TR7RVMan #760038 12/22/18 1:03 am
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Originally Posted by TR7RVMan
Hi Bruce, How do we account for the different experience? I had head off '67 Bonnie & the bolts came out fine. I was surprised on the '69 encountering difficulty. Since I've seen difficulty on a few other bikes.


Hi Don, I can only speculate that there may have been some quality control problems due to trying to produce too many bikes on antiquated production lines. Welds may not have been perfectly located from one machine to another for example. Otherwise perhaps frames have distorted somewhat over years of use and abuse. Who knows? I'm pretty sure that these bikes were originally designed so that the cylinder head could be removed relatively easily.

Bruce

Last edited by Bruce Martin; 12/22/18 1:05 am.

1937 Ariel Red Hunter 500
1970 Triumph Bonneville

Making the scene with the gasoline
Re: 1970 TR6 cylinder head bolts
Steve Guildford #760062 12/22/18 4:04 am
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Just done some experimentation on my being rebuilt1970 which I know has a straight frame and engine mounts. With the rockerboxes on tight, you can't get the timing side central head bolts in or out, particularly the inlet one. There is enough room for the primary chain side ones.

What I have seen done before now is file down the lower head bolt head on one flat to give the necessary clearance. Some preferred just to grind down a corner. A tube socket will seat on the remaining corners, particularly if you get the six sided sockets. Rough, but it works. The alternative is loosen the rockerboxes which allows them to be wiggled out.
Bruce - I am not sure they designed the heads to be removed easily- they were put in the frame fully assembled. I note that the Thomas Gunn overhaul manual specifically states putting the two 3/8" head bolts in first and tightening before putting in any of the others. On disassembly the words are "these bolts will clear the frame if both bolts are lifted and the rockerbox tilted.


68TR6P rebuilt as a C
70 TR6R
Re: 1970 TR6 cylinder head bolts
Steve Guildford #760129 12/22/18 9:05 pm
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Perhaps I'm confused here but I'm having a hard time imagining a situation where you would take out the engine cylinder head bolts without removing the rocker boxes. I've just never had an issue with any of the fasteners when removing or replacing the cylinder head. I consider it an easy job.

Bruce


1937 Ariel Red Hunter 500
1970 Triumph Bonneville

Making the scene with the gasoline
Re: 1970 TR6 cylinder head bolts
Steve Guildford #760819 12/29/18 6:22 pm
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Thanks chaps - update on my 70 TR6 (although actually a 69 made bike according to the star in the head) - when I loosened the rocker boxes the offending cylinder head bolts just cleared the frame. The inlet one was still v close and only just came out, but it worked.

Steve

Re: 1970 TR6 cylinder head bolts
Steve Guildford #760883 12/30/18 4:42 pm
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When refitting use same method, head on with outer bolts nipped up then r/covers and 4 inner bolts :-)

Re: 1970 TR6 cylinder head bolts
Bruce Martin #761047 12/31/18 9:06 pm
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Originally Posted by Bruce Martin
Originally Posted by TR7RVMan
Hi Bruce, How do we account for the different experience? I had head off '67 Bonnie & the bolts came out fine. I was surprised on the '69 encountering difficulty. Since I've seen difficulty on a few other bikes.


Hi Don, I can only speculate that there may have been some quality control problems due to trying to produce too many bikes on antiquated production lines. Welds may not have been perfectly located from one machine to another for example. Otherwise perhaps frames have distorted somewhat over years of use and abuse. Who knows? I'm pretty sure that these bikes were originally designed so that the cylinder head could be removed relatively easily.

Bruce


Out beloved Triumphs have a slew of hand-fit complexities that made them labor intensive to build and maintain. The number of different fasteners throughout the machine is disgraceful. Inventory control at Meriden must have been a nightmare, especially when transitioning to metric. My favorite complication is the sludge trap buried in the crankshaft. Another is the grease seal discs that are destroyed with every hub removal. I'll bet others could chime in with their suggestion for improvement, but the Japanese beat us to it.

Re: 1970 TR6 cylinder head bolts
Steve Guildford #761058 12/31/18 10:17 pm
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And modern machines are designed to be assembles in sub assemblies making some maintenance tasks a total pain in the neck. Working on either requires not just some mechanic aptitude but also a little mechanical sympathy and simple common sense.

If you need to reach for the angle grinder in order to remove a component then something is not right.

Rod


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Insist on something else.

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