Wheelmang

Rebuild of a 1926 DB 4 Cylinder

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Ray - Herm, I may have been a little confusing in some of my interpretations. The speed shop doing my crank etc is saying that the crank will be at less than .0005 tolerance. The original post of .01 was a typo on my part it should have been .001 That was the required measurement reading that I believe was given to me by someone who does babbitting so they could set rod and main bearings to crank spec. The actual main bearings will be line bored not honed. 

Is it OK to under size the crank? How much can be removed from the crank before it is not usable?

As to the crack repair, my welder now has the engine and I will be meeting with him the middle of next week to go over that process. He is military trained and now a retired welding teacher. At this point I am trusting his judgement for the best process but will definitely raise the various processes brought up here. 

Please let me know if I am missing anything here on the crank. 

Thanks all for you valued input. 

Paul 

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Paul, seeing as Herm is with us I am going to leave it to him.  He is the engine builder here.

 

Ray.

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I will post a few pictures later, however, there were a few surprises found on the clutch assembly. (Not the engine proper rebuild but thought it best to keep this all on a single project post.)

One of my discs is bonded and the others are all riveted. It looks like Myers sell individual unlined disc but other than the bonded the disc looks to be in good shape. Still has the print on the face. Should I go ahead and remove the bonded and reline with riveted? If so what process removes the bonded lining? 

Thanks

 

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I ordered 4 new clutch plates from Myers.  They came already riveted.  The only point that I would make is the way the lining material was riveted to the new plates.  The original clutch plates used open ended (hollow) rivets that are peened over at both ends.  The replacements used blind rivets and the heads are not very deeply recessed so in effect the clutch will not have a particularly long life.  That said, these cars seldom do high mileages these days so I am probably being over pessimistic.

 

Incidentally, how did you compress the clutch spring?

 

Ray.

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I had to make 1 clutch out of 2.The throw out bearing surface was severely worn on the one removed from the car and a couple plates were grooved.  Fortunately there was a spare transmission and clutch setting in my shop. Albeit a rusty one. 

Certainly the process used to remove the clutch spring is not found in any "best practices" instructions. Should anyone reading this try it - the spring does not appear to have much of a release stroke but be sure you do not stand directly in front of the vice nor put fingers in the open area to remove the c clips. Having clarified that, it actually worked quite well in the absence of a press. 

The OD of an old input shaft bearing was a perfect fit inside the spring housing. The outer bearing surface was cracked in the vise and the center ball bearings and inner race removed. It was then placed slightly off center on the spring housing in the vice and compressed.

 586346600_OldTBworn.JPG.c7c2922a72fc695ca386ea5f271dabef.JPG

The back side of the plate needed to be raised slightly, with the two raised sections on the vice jaws, in order to keep a slight down force to the front jaws. If this is not done the pressure will force the assembly upwards. 

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Once compressed the first half of the c clip was removed with a magnet and then pressure was released, the bearing moved to the opposite offset and the second half of the c clip attempted to remove. There must have been a burr of some kind as it did not just fall out. I slowly released pressure and the clip held while the bearing case was removed and pressure reapplied to the spring retainer. The c clip then fell out. (As just the jaws of the vise on the spring housing released enough pressure to remove the clip it made me question if the bearing race I used was even necessary.) 

 851360271_Springrem2.JPG.de3c4f166e031eeadfe1af19b947cfe4.JPG 

From there it was a simple matter of slowly winding out the vise to release all the pressure on the spring. 1545917999_Springrem3.JPG.34e23d5aada0d0c5278f7a3b6cd1c3a4.JPG

Then on to drilling out the old rivets on the clutch plates. I found this worked best by drilling the rolled side of the rivet as opposed to the head side. Most of them fell out or just pushed through that way. 

Clutch3.JPG.82537b4a29e07c4d9eb6714d43094b35.JPG

Then on to bead blast and clean up. 

Clutch5.JPG.f24523ce8b3a02351a34e6dfad116fac.JPG

Time to spend money at Myer's.

A real press will be added to my shop before reassembly. This wasn't the safest procedure I have ever performed but worked on the moment. 

Anyone know if any of these clutch components originally had paint or metal preservative? 

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That looks a whole lot easier and safer than what I did. A press is working it's way into the budget. 

Your throw out bearing surface looks like it also has some wear. There are major grooves in mine. Fortunately the spare had no wear. Way less movement in the throw out bearing now. 

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I expect you know, but it is advised that the two anti rattle springs are reinstated when you put it back in.

 

 

Ray.

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Both springs were missing and I do not see them listed at Myers. There were some partial pieces in the crud at the bottom of the bell housing but not enough to figure out a way to make new ones. Would you or someone have a picture to go from or possibly a source to purchase. 

Paul

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My welder friend Dave has advised that the cracks are repairable so on with the block repair. 

There was a second crack found at the base of the carb intake when the block was dip tanked and cleaned. Interesting that this was not leaking but we decided to go ahead and weld it anyway. Both cracks were cleaned up and channeled. There are holes drilled at each end of the crack to stop further running. 

Cracked.thumb.jpg.c732873e6ef4bbd2a5761634754d6952.jpg

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In order to weld on the cast iron it needed a temp of approximately. 400°. 2146165861_Heatingto400.thumb.jpg.eeb6031560c7889a2341da0fedf40972.jpg

Cast composition was tested and determined that the best welding process was TIG with 95% nickle rod. 

1312153101_TigWeld.thumb.jpg.8c31f7882145c5d17b74dbfbf39b7492.jpg

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Then a slow cool down with sand to absorb the heat.

1881256046_CoolDown.thumb.jpg.acbcc3bd01101451254a101ce09ccbe5.jpg 

I should be picking up the finished job tomorrow. Then back to my shop for grinding the welds smooth.

The speed shop has been advised to go ahead with the crank and as soon (likely a few weeks) as they provide me with the journal specs, the rods and mains are off to Herm for Babbitt.

Stay tuned!

 

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With everything forward of the driveshaft out and on benches, in bags and plastic bins there is no shortage of projects. Today was a quick one on the throw out bearing. It probably did not need to be totally torn apart but it was sitting there staring back at me all greasy and dirty and rusty. So here is what the inside of a 26 DB throw out bearing looks like all disassembled. It was actually pretty badly caked up with hard grease so it was a good thing to tackle. It came apart quite easily by grinding off the back side of the four rivets and punching through. 

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There were also some small ridges that had raised up on the left side of a few of the ball bearings. They came off quite easily by letting the balls drop to the lower part of the retainer. This allowed the ball to drop just enough out of the way. It then took just a lite stroke or two with a fine tooth file to remove the burr. 

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It is not completely reassembled yet as I need to find some rivets or more likely will get some machine screws with nuts, tighten up and a quick spot weld to hold all in place. It is working way smoother now.

 

 

Edited by Wheelmang
word edit (see edit history)
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I am going to replace the valve guides on this mostly because it seems like the right thing to do at this stage. Do they press out and back in or is it something more complicated that needs to be left to the engine rebuilder?

Thanks

Paul

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I pulled my guides because the method of using a cold chisel and hammer (described in the manual) seemed too risky.

 

Also, measure the new ones.  Mine were about 0.003" too big and I had to turn them down to fit snugly..  

 

You will presumably be renewing the valves.  The retaining pins tend to leave a groove in the retainers which prevents desirable rotation so it would be good practise to machine out the groove.

 

Your engine shop will be able to cut new valve seats which in my opinion is likely to be more accurate  than doing it yourself.

 

Finally, check the valves don't stick at any point in the new guides.  I thought mine were o.k. but I suffered a sticking valve on the first outing.  :(

 

Ray.

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Got to cleaning and painting the U-Joint housing and have a question about the shims that go between the housing and the back of the transmission. There are five of them. Two are .032, two are .023 and one is .013. That leads me to think that there is some kind of shim spec for that union. If that is the case how is the correct spacing determined. It is a looong way before I get to reassemble but will be good to know at the time. 

shims.JPG.9f76b7874d83e46b0bd92d7185a20148.JPG

Thanks for looking

Paul

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6 hours ago, R.White said:

I pulled my guides because the method of using a cold chisel and hammer (described in the manual) seemed too risky.

 

Also, measure the new ones.  Mine were about 0.003" too big and I had to turn them down to fit snugly..  

 

You will presumably be renewing the valves.  The retaining pins tend to leave a groove in the retainers which prevents desirable rotation so it would be good practise to machine out the groove.

 

Your engine shop will be able to cut new valve seats which in my opinion is likely to be more accurate  than doing it yourself.

 

Finally, check the valves don't stick at any point in the new guides.  I thought mine were o.k. but I suffered a sticking valve on the first outing.  :(

 

Ray.

Hi Ray:

Yeah the cold chisel sounded pretty radical to me as well. You say you pulled them. Could you please describe the process you used? 

All my retainers are refurbished and new pins made. I had just completed an interim valve job to get me to the point when I could do the whole engine up proper. Just didn't expect it to be so soon afterwards. Machine shop will be cutting new seats and all new valves and springs will be coming from Myers.

Thanks for the heads up on the oversize and sticking. 

Paul

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Hi Paul.

All I diid was make up a puller from a long bolt with a little distance piece under the head to bear evenly on the end of the guide.  I think I used a length of tubing on the other end or it may have been an old box spanner; I can't remember now but it was all quite simple really.  I seem to remember if the camshaft is out the guides can be removed from either the top or bottom.  You will see the original guides have a ribbed surface which I suppose is to help keep them in place.  Sadly, the replacements don't have this and are perfectly smooth.  I didn't attempt to give them a key other than the fine machining marks left by my lathe but they are in quite tight so fingers crossed they will stay put.

 

BTW.  When you get the babbit done I understand that the end play of the crankshaft is determined by the white metal on the sides of the centre main bearing caps.  Probably teaching granny to suck eggs but better safe etc.

 

Ray.

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1 hour ago, Wheelmang said:

Got to cleaning and painting the U-Joint housing and have a question about the shims that go between the housing and the back of the transmission. There are five of them. Two are .032, two are .023 and one is .013. That leads me to think that there is some kind of shim spec for that union. If that is the case how is the correct spacing determined. It is a looong way before I get to reassemble but will be good to know at the time. 

shims.JPG.9f76b7874d83e46b0bd92d7185a20148.JPG

Thanks for looking

Paul

 

I haven't seen any information about these shims so I just put them back the same as before .  You may find the original seal needs replacing but if it is OK then leave it in place.  I didn't know what was the best grease to use so went with a multi purpose grease.  I used plenty of lube on the universal coupling.

 

Ray.

Edited by R.White (see edit history)
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Thank you guys for the great pics and valuable info. Bookmarking for the future since I have practically the same automobile. 

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Thinking this thread should have been named engine and drivetrain rebuild. I am now into the transmission as long as it is out. It is looking like a few months before the "outside" my shop engine work will be done. Now looking to sometime in late October or November before the engine will be ready for re-assembly. So the first piece removed from the transmission was the idler gear? (Probably the wrong terminology.) The one removed (on the left) does not look to be in the best of shape. I had a spare and don't think that looks much better. Would you use either one? I am considering re-installing the original. it was working fine before removed. 

idler.JPG.76e151ca756693a6f052021bdea1beea.JPG

Anyone have a replacement that is in much better shape?

Thanks for looking 

Paul

 

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If it's the reverse idler I wouldn't be overly concerned since it only comes into play when tranny is in reverse.  The one on the right looks a bit better shape to me.

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