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MG MGB GT V8 Factory Originals Technical - Flywheel Dowel Pins
|The old Rover SD1 flywheel I have needs skimming to remove scoring, but I can't get the dowel pins out and the only machine shop anywhere near here won't take them out either - "No pal, you get them out, we'll skim it". I have tried tapping them from side to side and pulling them with a strong self-grip wrench, but to no avail. I heated the entire flywheel in the oven to 100 celcius, but no good.|
Has anyone any way to do this? Looking at some US sites, it seems that some people advocate simply grinding them flat and not bothering with them. The amateur engineer in me doesn't like that idea, but are they absolutely necessary?
|Simple solution. Clamp a piece of wood/metal to any drill press table, drill a hole in it the same size as the dowel, flip your flywheel over and put the dowel in the hole, now it is directly lined up with the drill bit. So easy a caveman can do it...Dale|
Are these dowels blind?
|D M Tetlow|
|I don't think they are Blind yet, but certainly are impaired. Ha! Hope to see & wife in Durham! |
|Yes they are in blind holes.|
|Perhaps I should have added that once you drill down to the dowel, drive them out with a punch. I have done this hundreds of times, there is no better way. Especially on hardened dowels or dowels that are seized in the flywheel, where a dowel puller has no chance.|
|Thanks for all the help. I eventually consulted my engineer pal Dave who drilled through the back of the flywheel a hole smaller than the pin, then punched them out from behind, just as Dale described. It isn't an easy option as the back of the flywheel is bevelled, not flat, so before drilling through he had to make a small flat area so that the drill didn't skate about all over the place. The pins can be put back in as there is still for a shoulder for them to butt up to.|
He then made a mandrel and mounted the flywheel in his lathe and refaced it. What does he want for all this work? Ten of our British pounds. I'll try to give him more. Guys like him are worth their weight in gold.
Interestingly, looking at the now smooth face of the flywheel there are obvious patches that look different. These are hardened areas due to the heat of the clutch friction plate Dave tells me. In fact he said the wheel was slightly warped by heat. Amazing when you consider the bulk of the thing. And so many, many people sit in traffic queues with the pedal down all the time. Everyone should be given lessons in how a car works so they can understand what happens when they press the controls.
|Sitting with the pedal *fully* down probably isn't putting much heat into the flywheel, certainly not as much as slipping it when manouvering. Some TV programme a few of years ago featured Maureen the 'learner driver' using so many revs she couldn't see where she was going for smoke and burnt out the clutch.|
| There is a tool designed to pull the pins out of the flywheel. It uses a slide hammer for force and clamps to the pin with a jaw. A transmission/clutch shop should have one. I turn all the flywheels myself when we do clutch work. When a clutch slips it generates a lot of heat. That heat creates the Hot spots. Those hot spots must be ground out or they will cause shudder. A flywheel must be ground with a stone not cut with a lathe bit. The bit wont cut out the hot/hard spot it will just bounce over them. The heat turns spots of the iron flywheel into hardened steel. If you can see the hot spots after the flywheel is resurfaced the job was done improperly. There is a learning curve to using the pin puller. If someone can't get the pins out it is because they don't know how or don't have the proper equipment. I will post pictures of the proper equipment later today, once I get to work. Ten pounds would be cheap we charge $25 for a flat and $44 for a two step flywheel.|
I normally post to the MGA section. I currently own 4. One of them is powered by a Mazda rotary engine. I do look in here occasionally and find the info quite interesting. At some point I would like to build a V8 MGA. I have owned and operated an auto repar shop, Japanese Specialists, since 1981.
|R J Brown|
|Here is a picture of the dowel puller sitting on the flywheel grinder.
|R J Brown|
|Randy, I thank you for your comments. Since my pal faced the flywheel with his lathe, I have had the same comments from another source. On carefully inspecting the hot spots, you are dead right, they are very slightly raised.|
It's all very well when you yourself obviously run a good quality machining shop, but Colorado is a fair distance from here!! Around here there is only one firm that does engine reconditioning within a 30 mile radius, and they have a poor reputation. This is the firm that didn't know how to remove the dowel pins - "You remove 'em, we'll reface it". But I have no other choice, so I went in to see them today, and the guy has a flat grinder like the one in your picture and he agreed to grind the flywheel for me, just enough to make it right. I'll pick it up on Friday, so fingers crossed that he knows what he's doing.
This thread was discussed between 20/11/2008 and 03/12/2008
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