Slingers - To Do or Not To Do, that is the question

[skogas]

This is probably the most common and difficult question for anyone who acquires a vintage BMW without knowing any history about it (and has limited budget).

Should I bite the bullet and do the Slingers as part of the rebuild, or should I just leave the engine bottom end alone for better days, and run the Russian roulette with the current Slingers.
I know there's no easy answer on this, but any input from experience would be appreciated.

My budget is fairly limited - I could afford buying the Multi-tool from Cycleworks and attempting to do it myself, however this would be my first engine rebuild attempt so I'm not sure if it's such a good idea (I'm ok at following instructions but the skill is not quite there).

I am doing the heads now - they were still the original 68mm diameter with the old 5 ring pistons, so I'm getting new pistons for first oversize re-bore, new valves and having the valve guide inserts done (so the machinist work tapped into the budget quite a bit).

Are there any indicators that could hint whether I should be getting into engine's bottom end or if it's still ok to run it another bunch of miles?

Apart from bike spending past 40 years in the shed and getting rusted everywhere it could - many "wearing" components are in surprisingly reasonable condition.
The valve tappets didn't have any pitting whatsoever, the generator brushes are still about 13mm in length, the pushrod's ends aren't worn and preliminary checking of crank doesn't show any play connecting rods play (as per Barrington book).

So it seems like the bike was maintained in general, which is good in one way, but also makes it hard to make a decision about getting into trouble with Slingers and engine's bottom end in general...

Cheers

[Matteo]

How many miles on the engine? I assume no previous rebuild.

[skogas]

Hi Matteo - very hard to tell milage wise, as I don't have a history of the bike really...
The speedo wasn't original (the bike is 1955 and speedo is from 1959).

Speedo had 67k miles on it, with label of being last checked in 1972 by N.H. SPEEDOMETER & CLOCK from North Hollywood, when it had 63k miles - that's all I can tell

[schrader7032]

Yikes, with that much uncertainty, I'd have to consider doing the whole shebang. The thought of riding around with serious doubts in my mind would really get to me. At a minimum, I might say ride it for a short period of time to see what else might be wrong and then fix the rest of it.

I'm like you...it might be possible to get all the tools and take things apart, but the serious money is know what to replace and getting it back together again...and done right! For my bottom end work, I did everything but pull the engine...I delivered the case and bottom end to the mechanic...then picked it up when done. I did all the work on the disassembly and reassembly. It helps some...but it's still costly.

[808Airhead]

As a professional German car mechanic and vintage BMW owner,I would like to give you my OPINION. A vintage BMW is a luxury,nobody NEEDS a vintage BMW,and it should be something that gives you pleasure since it is,after all, a luxury/hobby. You do not NEED to ride it in its current unknown state,and if you ride the bike like that you will get away with it for a little while............. nobody knows when or how long before it will self destruct,only the bike knows!
I recently rebuilt my low mileage original 64' R60/2 engine and with only 17K miles it had borderline big end wear and the rear bearing seat had worn away and "spun". With 67K miles,there is a good/great chance of some horrors awaiting you. MY rebuild is over 2.3K in parts and that is with doing all the labor myself other than the crank rebuild,re-bore,powder coat, and head machining. These bikes are not cheap toys and they cost $$ to rebuild correctly.
As a "first" engine rebuild.......I would say NO on this type of engine. You really have to have a modicum of experience with engine rebuild/engine theory before attempting this. Take it to someone to rebuild WHILE YOU STILL HAVE SOMETHING TO REBUILD. If you drive it and it ruins the crank.....rod seize/takes out case/barrels.....you will end up with a WAY more expensive rebuild than just doing it now.

"You have to PAY to PLAY"--------Confucious

[nedhoey]

I don't think anyone will tell you it is ok to skip it. It simply isn't a good bet. The slingers in old rusty barn (or shed) bikes like this always need work done to perform properly. Slingers are nearly always more dirty and gunked up than hoped for or expected. Even if they still would perform at 70%, it would be worth doing. They're too important.

There will be no regretting getting it done. There could easily be regretting not getting it done. Especially once the expense is in the past and you're on the road.

[skogas]

Thanks guys, really appreciate your feedback.

It sums it up pretty well and sounds like there's no "magic bullet" solution for this one. I just wish BMW made it tad easier to peek into those bloody slingers, but hey - it's all part of what we're buying into with these bikes...

So I guess the next steps for me would be to:
1) Search for a mechanic here in Melbourne who is experienced and can do such job (and hopefully an affordable one too)
2) Start saving money to pay for it

By the way - is transmission/final drive overhaul generally considered being a must too, or is it more of a "fix it when it's broken" type of thing?

Thanks again!

[OldBeemer]

Call Gyro (Graham Carless) and have a chat to him. Work number - 9354 9658 - 3 Louvain St Coburg Vic 3058 Australia. Of course it will cost - but in my humble opinion he is the best we have this side of the Pacific - and I am biased - as anyone who has had him do an engine - a trip to his workshop is priceless and so is his experience - ask BMW !!! .

Cheers
Ade

[speight1823]

I have worked on quite a few pre 1970 BMW's and never seen one with clean slinger grooves. Most failed big ends have slingers full to the brim with muck and with a trail of muck going into the big end bearing. Don't take a chance on not stripping the lower end . Repairing a failed crank shaft it the one job you will not be able to do yourself and it is by far the most expensive thing to get done.
Should you do the work yourself? I would say have a go.This is the fun part of owning an old vehicle. About half the professional BMW restorers in our neck of the woods have not had formal engineering training and yet they do a good job.
If you crank is OK you probably just need a set of gaskets , seals and bearings.
Work slowly and meticulously .
You have a wealth of experience and knowledge available with this group ask plenty of questions and you will be fine.
At the end of the restoration you can take pride in your work and of it breaks down you will more than likely be able to fix it.
Good luck and enjoy.

[malmac]

My son has an R60 and I have an R69s - we are currently doing an overhaul job on his bike which includes cleaning out the slingers.

We have an OK workshop and the ability to fabricate the pullers and such necessary to dismantle these engines - however it has taken many hours and we have yet to reassemble the engine.

So to really do the job you need time, money and of course a suitable workshop and the tools needed to dismantle and reassemble the engine. It can certainly be done if you either already have the skills or are prepared to take it slowly and learn the skills you need.

Attached progress photo of the timing gears before we pulled the crank.

Mal
Toowoomba