MG Midget and Sprite Technical ASeries front camshaft bearing renewal. Easy&cheap BBS discussion at MG-Cars.net

MG Midget and Sprite Technical - ASeries front camshaft bearing renewal. Easy&cheap

If you allow me to finish 7 posts sequentially, before any replies -- if anyone wants to -- it'll make it easier to follow later. ======================================= How to do an A-Series camshaft front bearing renewal, EASILY, QUICKLY, and CHEAPLY. (I'm not sure if this would work in the same way for a 1500 Triumph engine. I haven't got one to test it on. But in principle, I can't see why not, other than perhaps you can't get the same type of bearing.) ------ Some of you may remember the oil sucking threads. Some of you may remember that about a year ago, in attempting to identify the exact cause (I failed), I did at least identify that my front camshaft bearing was knackered. I also confirmed that the other two camshaft bearings were barely worn at all. This is apparently quite common. So I decided to only replace the front camshaft bearing. I removed the front bearing with the intention of having it replaced professionally. But as is my nature, I just couldn't bring myself, to pay someone else to install the new camshaft bearing, without first establishing that I couldn't do it myself. The upshot is, that I did it myself. Not only VERY easily, but quickly, and VERY cheaply too. In fact it didn't cost me a penny to replace it, other than the cost of the new bearing of course. Here's how. I drifted the old knackered front camshaft bearing out, with a home made tool. It's just a short section of an ally scaffold tube, that I cut a slit in, to reduce the diameter, to enable it to slide through the empty front bearing hole in the block, as I drifted the bearing out. I used a bit of threaded stud and a couple of large washers, with a little help from a hammer. The bearing came out quite easily. Here's my home made removal tool. Part 2/7 follows.

Lawrence Slater

Type of bearings to buy. Most (not all) people say that camshaft bearings have to be either reamed or scraped after they are installed. However, this only applies to split ring unfinished bearings. If you buy solid ring PRE-FINISHED bearings, they are advertised as not needing to be reamed. I can confirm that. They don't need to be reamed/scraped. Here are the two types side by side. Part 3/7 follows.

Lawrence Slater

Installation tool. How do you install the new bearing in the engine block without a professional tool? You make your own. In fact, if replacing only the FRONT bearing, you don't even need to make a tool. You already have one. It's called a camshaft. It's quite likely that you're replacing your camshaft, if you are replacing a knackered camshaft bearing. Hence, you can use your old camshaft as the installation tool, with no worry about damaging it. But even if re-using the old camshaft, or only have a new one, you can use that too, because this doesn't damage or alter the camshaft. First, install the camshaft sprocket onto the camshaft, BACKWARDS. Put on the retaining nut, but only tighten it to sit flush with the end of the camshaft. This will give you a FRONT camshaft bearing installation tool, that because it runs through the existing two other bearings, exactly lines up the front bearing, as it's pushed into the block. What could be simpler, or cheaper? Maybe something, but I can't think of it. – Unless of course you already have, or have access to, the correct tool set. Here's a picture of mine, assembled with my OLD bearing in place. The picture shows the OLD bearing on the camshaft, because I forgot to take a picture before I started to install the new bearing into the block. :- Part 4/7 follows.

Lawrence Slater

LINE UP THE OIL HOLES!!!! I marked the block to show the exact position the bearing would need to go in at. I used the main oil feed to camshaft bearing, as my guide. The additional advantage of these Glyco bearings, is that in these bearings, the oil feed hole to the cylinder head, is larger than the hole in the engine block. This makes it much easier to get the main oil feed slot/hole, lined up exactly where you want it to be. This is a picture showing my markings for the oil hole alignment. It's with the OLD bearing in place. The split was widened, to allow me to reduce the diameter, so I could slip it in and out by hand. Part 5/7 follows.

Lawrence Slater

Installation. Oil the new front bearing, inside and out, the bearing retaining hole in the engine block, and the existing camshaft bearings in the engine block. Slide the new bearing over the camshaft, and onto the front journal. Carefully slide the camshaft/sprocket/new bearing assembly into the block, paying close attention to the relative positions of the oil holes in the new front bearing, and the engine block. The rear and centre journals, will just enter the rear and centre bearings (if you don't over tighten the sprocket nut), thus aligning the new front bearing perfectly. The new front bearing will be sitting at the face of the engine block, with the chamfer of the bearing, just inside the bearing retaining hole in the engine block. It looks like it'll work to me. Famous last words? Part 6/7 follows.

Lawrence Slater

Ready to go? The reversed camshaft sprocket is a perfect surface to press against the lip of the new front camshaft bearing. The camshaft journal, prevents the chamfered lip of bearing folding in and being damaged. Hit it with a hammer! I could have welded, or drilled and tapped, some threaded stud to the rear of the camshaft, and pulled the new front bearing into place in the engine block. However, research online showed that many people simply drift them in without problems. Because I like simplicity, that's what I did, and why I didn't need to alter/damage the camshaft. With a tad more care, I could easily have used my new camshaft, and would have done that, if I didn't have an old one. But I didn't need to. With the block vertical, my 'camshaft bearing insertion tool' assembled and in the ready position, my oil feed holes lined up, and it all lubricated, I placed a bit of wood over the nose of the camshaft, and thumped it with a 4lb club hammer. It was very satisfying to see the new front bearing gradually, but easily, sink into the block. I continued to drift the new bearing into the block, until the bearing reached a point where it was almost flush with the face of the block. I had to stop at the point. Because the reversed sprocket rim sits proud of the inner circle, I couldn't push the bearing in anymore with the sprocket. I could have made a packing washer to sit behind the sprocket, which would've allowed me to continue. But I couldn’t be bothered, since I already had a 'tool' that would complete the job. Here's a picture showing the new bearing, a little over half way in. Part 7/7 to follow.

Lawrence Slater

Tools to complete the job. With the lip of the new front camshaft bearing, now almost flush with the face of the engine block, I removed the sprocket from the camshaft. I left the camshaft sitting in the bearings, to prevent damage to the lip of the front camshaft bearing, as I completed the job. I then used an old brake calliper piston, that I had left over from a Girling 'type 14' calliper rebuild. It's the perfect diametrical size to sit over the threaded nose of the camshaft, and exactly on the lip of the front bearing. It's also EXACTLY the right depth, to be able to knock the bearing in flush, but NOT knock the camshaft rear lobe, into the inner face of the rear of the engine block. -- About a 1mm clearance. Once the new camshaft bearing was in flush, I used my other 'tool'. This is the same tool I used to remove the old bearing. Again, leaving the camshaft in place to prevent damage to the lip of the bearing, I carefully drifted the lip of the camshaft bearing, just below the surface of the block face. I did this to maximise the oil feed to the front camshaft bearing/journal, from the main crankshaft bearing/journal, whilst still ensuring that the oil feed to cylinder head from the camshaft bearing wasn't obstructed at all. Here are picture of the tools I used to complete the job. And that's it. Done and dusted. A complete, quick, cheap, and easy job. Much easier than I expected in fact. I'll now get on and build the engine. Feel free to critique my efforts.

Lawrence Slater

I had dreams (nightmares?) about how to do it Guy. But in the end, it was so simple. It really surprised me just how simple it was. Shame if it can't be used on a 1500 then. Maybe a B-series? And here, by the way, is my NEW camshaft. It's a brand spanking new, BMC old stock item. It was on sale on German Ebay, badly worded, and seemingly not noticed by anyone else. I paid 50 quid for it plus 10 quid postage. However, because they failed to describe some very mild surface marks on the centre journal, I asked for and got, a 10 quid refund. I polished out the surface marks with a non-scratch nylon pan scourer, and some liquid metal polish. Not a mark left on it. Bit of a bargain I think, esp' for a spyder drive, which are getting a bit scarce.

Lawrence Slater

TBH I didn't much like the Spittie. I thought it was too heavy for the engine. I did think it looked nice though. I saw one in Tarbert not too long ago. I had a Mk2 GT6 in the early 80's. It was a total rot-fest and I blew it up thrashing it and scrapped it. My great regret is that I didn't save the O/D gearbox. I'd love to have that back for my Midget. The one in the Shed is a Mk3. I've posted the pic before but here she is. I think she needs a set of Minilites. What do you reckon? I'm booked to do a top end rebuild this winter, side by side with the 1500. Should be fun, but ATM I'm flat out on a couple of fishing boat engines. BTW if anyone knows of a stash of bits for Gardner reduction boxes I'd be interested. I think maybe Noah's decendants might have something under the bench LOL.

Greybeard

If the block was warped or damaged, it would likely have happened when the previous camshaft bearing was in there, and you would have known about it because the camshaft would have already eaten into the bearings, and I guess vicky verky. Plus, what David just said. I'll repeat my 2nd post. "Type of bearings to buy. Most (not all) people say that camshaft bearings have to be either reamed or scraped after they are installed. However, this only applies to split ring unfinished bearings. If you buy solid ring PRE-FINISHED bearings, they are advertised as not needing to be reamed. I can confirm that. They don't need to be reamed/scraped. Here are the two types side by side. " =============================== They don't need reaming. That's the point. That's why I bought them. And why I wrote that I can confirm that they don't need reaming. The split ring type can indeed be installed slightly off square. But the solid ring type can't. Hence they are prefinished to the correct diametrical clearance. I've checked that with my NEW camshaft in the block AFTER I installed the new front bearing. Spins freely. So if your only reservation is that, and you enjoy doing things for yourself, and derive satisfaction from it, saving 20/30 quid, and time, then this is for you. If you don't particularly enjoy those things, take the block to a machine shop.

Lawrence Slater

Dave Barrow. I didn't mention it, but I did actually think of turning the blow torch on my block, prior to the deed. But I forgot. :- It makes sense though. I reckon you could almost push them in, if the block was hot and the bearing cold. In the event though, it was easy anyway. Greybeard. Precisely. Each time I've had my engines apart over the years, and when I'd had the cam bearings replaced back in the 80's, I could see that it was only the front that showed any real sign of wear. That's why I only replaced the front on this engine this time. I really only replaced it, because it had a deep score in it, and because I was looking for the elusive cure to oil sucking. I'll know when I put it back together if the oil sucking's been cured. I doubt it though, so I drilled the block for an additional breather where the mech/petrol pump blank is, in anticipation.

Lawrence Slater

:).

Lawrence Slater

This thread was discussed between 19/12/2015 and 01/01/2016

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