Has anyone got any experience with the baby "jump start" battery boxes?

Right now specifically interested in using one as a 12V power source for the alarms and anti theft devices on Her Ladyships BMW K1200LT which flatten the bike battery in about 6 weeks - 2 months. Garage in separate block so no power. I figure that she can easily pull something that small and, basically, portable off every week and take it back to her flat to recharge overnight. Presumably when it goes back on again it will top up the main battery whilst looking after the alarms et al. If I find one that works for her I plan to get one to do same job on my P38, which usually needs a top up charge a couple or four times a year if I'm not out and about much.

Problem is deciding on what is a good brand, which capacity specification to believe and whether a separate 12 DC output alongside the jump start one is useful. far as I can see most of the usual suspects quote the capacity for the USB 3.2 / 5V output in milli amp hours to get nice big numbers. Real 12 volt capacity seems to be around 1/3 of those numbers. Say 1 1/2 to 3 amp hours for the under £100 market.

Clive

Drawings and blurb in your E-Mail.

Holding straight is really only an issue when working solo. Those arms get heavy pdq! The bend really doesn't help.

Clive

RR

PM me with your E-Mail and I'll throw a pdf copy of my "complete" tool drawings across.
More than you need but its all there.
I think! Needs someone else to check them anyway.
My drawings are for one actually intended to be used with a pull screw as per the Laser tools "doesn't actually fit a P38" jobbie. Tried my set. It would work but nuts take a deal of turning to generate enough force to shove things in. Realistically a press is far better. Worst thing about press is holding things straight. Not quite got that bit sorted for doing on my own yet.

Or if you don't fancy making I guess I could box my bits up and send them by courier.

Clive

Rcutler wrote:

Yes I am hoping we can sort out another weekend, as again the radius arm and suspension work looks like a great plan. It might be worth trying to loosen some of the bolts before we head down next time. Obviously re tighten but an angle grinder was used on Gilbertd's car. Also the bushes do not come in a kit make sure you have exactly enough.

Best to get all new bolts and assume the old ones will need to be cut. Centre tube on my factory fitted bushes was alloy so corrosion lock against the steel bolt was inevitable given time. Sheradising, zinc plate et al will hold things for a while but anything much past ten years and you are on borrowed time. Cadmium plate is an effective protection but that's been verboten since about the mid 70's.

One of mine came out with (great) difficulty. The other three I eventually gave up upon and had to cut. No way I was re-using the old ones so wasting most of the afternoon trying to get them out was less than clever. Next time if two or three bashes on a bolt end don't drive it through far enough to hide the thread its getting cut. Or just cut and be done.

Clive

Its worrying how marketing buzz wins out over proper engineering.

It should be self evident that a polybush system can only work as advertised "provide improved control due to consistent steering geometry" when used as a cheap substitute for rose joints. With a bit more compliance for better NVH (Noise, Vibration, Harshness) levels. Rose joints are rough riding. Of course any significant compliance promptly interferes with the preciseness of the steering geometry. Somewhat contradictory. Time to quote Emerson.

Most road vehicle suspension systems aren't geometrically good enough to work freely over the full range of movement when rose jointed so the compliance of rubber bushes not only controls NVH but also gives that essential "give" to let things articulate properly. If you start seriously looking around car suspension systems its clear that there is some pretty serious engineering going on in the rubber bits. They don't do void bushes and the like for fun.

P38 suspension geometry is basically that of cantilevered leaf springs. Whatever your views on old fashioned, cantilever leaf springs with solid axles are a pretty good system so long as the tyres have reasonably deep sidewalls, especially when stabilised with a Panhard rod. So long as you ignore the inconsistent friction and self damping characteristics. Which is probably OK if you keep below 50 mph! P38 variant keeps the advantages and sorts the friction / damping issues but has to have controlled compliance. Rose joint it and it will pretty much lock solid in roll. Bump steer is going to be interesting too. Rigidly consistent steering and suspension geometry you don't have. What you do have is carefully balanced and compensating "compliance errors" that make the system work well. Appropriate sized tyres, deep sidewalls not boy racer rubber bands, being more than a little important too.

Given that Richards orange poly bushes worked pretty well for a decent mileage the the things clearly don't work the way the maker claims. Cheap Britpart et al blue version falling apart in pretty much nowt flat show what happens when they are sort of made to theory and hammered by 2 tons of P38 saying "I'm rolling so shut up and take it".

Not sure that I'd be happy spending money on something allegedly "better" that just doesn't work the way the makers say. Also deeply skeptical of the development abilities of "we make (aftermarket) bits for any car" firms against the real vehicle manufacturer who is going to put serious resources behind getting it right so they can make many thousands of cars and keep the customers somewhat happy. Whatever your views on Rover and BL in general the primary failings were production side, not engineering side. Bearing in mind that hitting the price point is hard and engineering compromises are inevitable. Which sometimes don't compromise as happily as was anticipated.

As the man says "sell the sizzle, not the steak". Most customers aren't equipped to analyse things properly. Especially as new "near enough to sort of work" will, initially at least, be an improvement on tired old soggy standard. Remember the instructions on all those snake oil economy devices "First give the car a full service and tune up so its running properly". Might as well have stopped there and saved on snake oil. Or the old motorcycle tuners trick. Put a decent step about halfway up the power curve to make them rev it out properly in second and third. Feels faster but why not just rev it out in the first place!

Clive

Never cared much for affordable laser pointers in alignment devices. Too much futzing around to get them closer than sort of right as body and beam are rarely well enough aligned.

If a two piece device, one part plugged in the axle case and one part plugged in the swivel hub is OK, easy way is to make the facing ends square so any mis-alignment shows up as a step. Visible if large, finger feel if small.

Way I'd tackle making a two part device would be to start with an over long chunk of metal in the lathe and centre drill the far end for tailstock support. Turn one end down to sliding, shake free fit in the axle case and the other down to a similar fit in the hub leaving a section of suitable length in the middle oversize. Over to the mill and cut the oversize middle part square. Slice into two parts apart around the middle of the square bit and face ends true.

Insert the two parts in axle case and hub respectively, turn so a flat side of each square is on top and slide together. Look and feel for mis-alignment. If you want to be really precise bore both sides to take a reasonable size rod. Sliding shake free fit again. But its got to be made dead nuts in line on both to be worth the effort. I probably wouldn't bother.

Centre bit doesn't have to be square. A simple flat will do. Carefully filed if thats all you have. If you are young enough and desperate enough ways could be found to do it on a Chinee Mini Lathe! I'd ask someone else.

Clive

Looks easy enough to make the alignment tool, or an effective substitute, if the dimensions were known.

If anyone has the sizes I'll make one that can be loaned out as a forum resource.

Allegedly the dimensions are out on t'net somewhere but darned if I can find them.
Picture of a home made one comes up fairly easily, usually with associated comments about sizes and promises to post them but ...

Given a complete axle it could probably be reverse engineered without major problems. Saving the usual "(expletive deleted) thing is (expletive deleted) heavy" issues. At first sight the official version seems rather over-engineered. But never having used one there may be reasons that are not obvious to a casual observer.

Clive

Gilbertd wrote:

Clive603 wrote:

Depends on whether it behaves like nylon or delrin.

Problem is it behaved more like marshmallow! Not like plastic at all, very soft and squidgy but also very tough to cut with anything.

Urg. Sharp Rotabroach will shift that sort of stuff but big issue is controlling the feed through rate. With the slow spiral on the flutes its going to want to pull straight through in about a turn or two. if it does that the big issue becomes whether or not you have the power to make a complete rotation at the end and snap the whole mess of swarf off. Alternative is a controlled low rate feed which will nibble it out in little balls. Which does work with rubber but you have to get the rate of feed right otherwise it squishes in under the cutter which takes occasional big bites. Not the sort of thing that's easily done in the ordinary garage workshop. With rubber best answer is to freeze it and hit it fast before it cottons on to whats going on. Even if freezing works for ploy bushes a complete radius arm will need an industrial freezer!

If its that soft a Forstener bit might work. Cut will have to be in thin slices so you still have the issue of controlling feed. The edge might hold it back enough so things can be controlled. Lubricant will help. Synthetic cutting oil would be best but normal folks don't have that sort of stuff about the place. WD40 spray should work adequately.

Clive

Rcutler wrote:

The problem with drilling it is as we tried with a hole saw. (Good ones I might add) is that the minute it got hot it started to melt and jamming the tool.

Getting hot and nowhere for the swarf to go is always the issue when using holesaws on anything other than sheet metal and similar thin stuff. Unsurprising I suppose as thin is what they are designed for. Which hasn't stopped me sacrificing a few in the interests of "getting 'er done wiv wot I've got" despite inherent unsuitability. Really doesn't help that, most of the time there is no recourse but to run them far too fast. Mr Starrett puts a nice speed chart in the box with his. Sometimes I think I'm the only guy who has actually read one. Reading and following being slightly different matters of course.

Nice thing about Rotabroach type cutters is that they have proper arrangements for swarf extraction. I imagine the usual rules for plastic would apply. Razor sharp, run slow (so it doesn't warm up) and heavy feed for a thick chip mechanically strong enough to spiral out. Maybe done in short bites and lubricate the centre stub or maybe just push on and let the centre burnish smooth. Depends on whether it behaves like nylon or delrin.

Experimentally heating plastics is something I tend to avoid. Frequently you end up with smoky, smelly or a mess. Often all three. Which offends angainst my conceit of knowing what I'm doing.

Clive

Imagine an annular cutter (Rotabroach) is the tool most likely to shift stuck in poly-bushes without excessive verbal encouragement. £60 + a pop in that sort of size tho' and really need a vertical mill to be confident of alignment. Right size pilot rod ought to work but how central the hole will be after many miles is open to question. Still have to cut undersize to be safe but scraping a couple of mm or so of left over polybush tube out isn't the end of the world. 2" twisted wire cup brush would be the tool of choice for that but I've not seen them that small for years, 2 3/4" seems to be the bottom size nowadays.

Clive

Gilbertd wrote:

I thought they only ever fitted SUs but someone may have swapped them for Strombergs which are the only other dashpot style carb I know of.

Just had a shufti at the James Taylor bible on the Rover V8 and was surprised to discover that Strombergs were a much more common fitment than SU from 1973 to 1989. I guess cheap'n nasty copy has its attractions!

Anyway that ambulance is something of an oddball. Quaife diff suggests it should be a Metropolitan Police Rapid Intervention Personnel carrier mini-bus. Apparently Met Police were the lead customer for the V8 version of the Sherpa aka Freight Rover V8. Ambulances were probably most common. A Quaife diff seems overkill there. Especially at Quaife prices!. Engine is basically the ordinary SDI one as used from 1977-1981 and in the TR8 in "Saudi-tune". 8 to1 compression ratio, 132 bp and 186 ft lb of torque, couple more ft lb and 3 bhp less than the Rover installation. OE carbs were Stromberg 175CD-(SET?). I imagine its now wearing SU HIF 44 to Land Rover One Ten and Ninety 1986-90 settings. Whether it also gets 134 bhp and 187 ft lb is anyones guess.

Allegedly these V8 Sherpa things can exceed 90 mph even when fully loaded. Yikes! Seems to be pushing the envelope a bit given the close relationship between Sherpa chassis design and that of the old J series Transit competitor. Short legs and narrower body of the J made a lot of sense for local tradesman guy. But they also somewhat channel the old Austin A30 tendencies to falling over in abject terror when confronted by a corner at anything approaching normal motorised vehicle velocities. Which doesn't seem a good basis for something that quick!

Plenty of varieties of CD carbs made over the years. Mostly licence made versions of the cheapy crappy Zenith Stromberg copy. OK (ish) when new but putting rubber diaphragm flexibility into the carburation characteristics mix is not a good idea when things get old. Especially so with the dashpot-less, air damped Bing version beloved of BMW Motorcyles. Which I shouldn't really grumble about having made a fair bit of beer money over the years from knowing how to set up the orrible things so they stayed set up.

Clive

Standard Rover so SU HIF, probably HIF 6 or HIF 44. Possibly the front drillings are different but the usual gaskets are universal with redundant holes.

Sorry can't be more help but the only SU's I've had serious dealings with over the last 20 odd years are the ones on my rotary engined Norton Commander and they are, ahem, weird.

Clive

+1 on the impact gun for shifting bumper bolts. I expected mine to shear but cheap LiDl special electric impact gun shifted them just like that. Looking at the bolts after removal the actual engaged thread and bolt shank was decently clean and rust free. Thick rust on the bit sticking up past the thread holding it in. Now on the tri-annual pull out and lubricate schedule.

Easiest bumper to remove & refit that I've ever met. Heavy but easy.

Hafta say I've been very impressed with how the various nuts and bolts have stood up to the environment. External corrosion yes. But quite light really given the age of the car. Business part, threads and where the bolts go through things have all come out very clean. With one exception. Those darn radius arm bush bolts. One out, three cut. Un-surprising as the inner sleeve of the bush is alloy, on mine at least. Asking for trouble.

Clive.

Was hoping to make it to lend a hand and generally meet folk but still waiting for FlatDog to deliver the stainless steel exhaust I ordered three weeks ago yesterday. "Yup, we have it in stock and it will be going out on Wednesday, should be with you Thursday.". Flexible friend took the strain. Three hours later phone call "Sorry it will be going out next Wednesday." OK can live with that. Check last Wednesday for an anticipated delivery time. Nope not going till next Wednesday (today). E-Mail this afternoon says it has shipped. We will see.

Meanwhile still running around with tails of wadding hanging out the back boxes. Not the sort of thing you want before embarking on a 250 odd mile round trip. Things probably won't break but...

I shall be well pleased (not) if it turns out to have been drop-shipped.

Clive.

Re the grinding paste on a screwdriver for extra grip. If you've not got grinding paste in the garage, I guess most folks under 45 haven't, there is a made for the job nostrum called ScrewGrab which claims 800% increase in grip. American made and, allegedly, effective. About £7 for a 15 ml squeeze bottle off E-Bay. I bought a bottle, but have yet to try it, despite having a lifetimes supply of grinding paste picked up for next to nowt nearly 50 years ago. Looks to be more convenient to use.

The 1/4 hex diamond coated bits have rather more grip than a plain screwdrivers too. Although folk associate them with woodscrews and house DIY "HoneyDoo" jobs I frequently use them on vehicles.

Also the cheap ratchet lever thingies for 1/4" hex bits can be a lifesaver when something is a bit stubborn. Especially if a screw head is at the wrong angle so you can't go straight in but there is room round the sides. But don't forget to push down on the top knob to keep the bit engaged.

Clive

Did my big radius arm bushes, and the rear rubber lumps, back last summer at around 89,000 miles and 18 years. Objectively a bit early judging by the general condition of the removed bushes but produced a noticeable improvement in all forms of stability including roll. Wasn't bad before but clearly getting older. In my neck of the woods there are some horrible more or less straight longitudinal dips and weaves in the road surface that really bite when it comes to straight line stability, roll steer, bump steer et al. Not purely a Rangie effect. Everything suffers.

Starting to feel things a bit again so Panhard Rod bushes on this summers job list. Which makes pretty much all change for the front end over the last 10,000 or so miles. Mimbling over the steering damper.

Clive

I suspect those 4 big bushes in the front radius arms get involved in the anti roll business. With the axle connecting the radius arms any roll means that one side of the bushes needs to squidge and the other side stretch. Which doesn't really happen with solid rubber so the whole thing has to distort and shift too. Between the 4 bushes there is a lot of solid rubber involved.

Probably more of a speed related effect anyway. Sharp inputs at high speed being more likely to invoke things that more normal driving. Big squidgy tyres probably cushion any steering / handling effects too. For my money its more about controlling the body movement than steering / handling although with the steering box on the car and drag link connection there is some (theoretical) potential for roll steer.

Scary thing on a P38 is how little there is actually connecting the body to the axles with any degree of rigidity. Just a panhard rod and rubber bits at the ends of the radius arms.

Clive.

Slump moulding from a thermoforming plastic sheet such as ABS may well be the absolute easiest reasonably clean method. Basically you heat the plastic to its thermoforming temperature and let it drape over or into the mould under its own weight. I've done bends in perspex that way and folk on the internet suggest that not too complex components can be reproduced in ABS but I've not a clue as to whether its capable of getting close enough to make a functional brake shield profile. Obviously the size will be a touch different but I hardly think the extra in draping over the outside of an original shield will be important. Unless the old one is super tatty it can probably be patched up enough to give a functional mould.

I've had ABS vacuum formed commercially over simple wooden moulds I made myself with good results for £ very reasonable in the (fairly distant) past. Possibly worth an investigate.

If you need a set of new ones as masters for the fibre glass route then it needs to be a group buy kind of thing. Finger in the wind suggests that 10 sets is about where it starts making financial sense. If you have to buy a set to make a mould from might just as well put them on and be done with it!

I always felt small glass fibre work was much harder than bigger jobs. Big bits stay put much better and you can roll the fibres down well for a good finish. Small jobs tend to jump around the bench and I never really got the knack of stippling the layers down without dragging pointy bits up on the return. Little narrow rollers were a pain too. But hating the stuff and job wasn't exactly motivation to learn properly. Always method of last resort. Actually method of no resort for forty odd years. Which worries me not at all.

Clive

Not sure about metal spinning. Bit of an art form and, so far as I can see no good DIY / Teach Yourself texts. Its on the bucket list of things to try to do properly before I die. I have spun a simple rim over OK (ish) but in all honesty the difference between OK (ish) and Gawd thats Really Ruff was more luck than judgement.

Basic shape can be spun easily enough but the U shape cut out has a rim that won't come out of a circle so that bit will have to be pressed. Of course if the basic dish is spun pressing the details becomes much easier. For spinning best to keep it thinner and do a return edge rather than try to make it thick enough to be stiff enough. Considerable forces involved when pulling into corners. 2 mm alloy will most likely be severely marked.

I wonder if metal loaded filler would be strong enough make press tooling good enough for pressing out a few sets in alloy. Carefully work a couple of layers of plastic sheet over each side of the master to bulk up the inner and outer tool spacing as alloy needs to be thicker than the original steel and act as a release agent. Fill as appropriate with a backing plate so the press tool is properly supported. Line up carefully with the alloy between and squeeze with a press. Sounds as if it ought to work. Still best to spin the rim.

Clive

Gilbertd wrote:

If someone was to buy a pair of new ones it would be dead easy to take a mould off them and knock them up in fibreglass. They don't need to be steel after all, they only keep the crap off the inside of the discs.

Yeess. But total Yuck job. Especially if you aren't geared up to handle the horrible stuff. Bought into that idea to copy an unobtanium sheet metal Velocette dynamo drive belt cover when I was about 20. Got it done, eventually but absolutely never again. Young, stupid and bloody minded isn't a good combination! Mould is still kicking around somewhere.

Frankly pressing from aluminium with basic dies in two or three stages looks a better bet if functional rather than exact will do. 16 gauge / 1.5 mm should press to shape OK with a workshop level press. Do centre first, then main back and edge. Spin the rim and trim round I think rather than final stage press'n shear. Dimple for strengthener and bond the extra piece in. Probably a week or so of (very) part-time work to draw and make adequate dies at my "Grumpy old man doesn't hurry for anyone!" speed using the Bridgeport and 1024. But is there enough market for them. Need to flog off 50 + sets at £50 (ish) a pair if its to be worth the effort.

The more I see of this sort of thing the more I wonder if its worth outing the Bridgeport and putting a proper VMC in as the entry costs have dropped like a stone over the last decade. Like serviceable Haas for £10,000 - £15,000, Fusion 360 for the CAD and G-Code is free. When it comes to home shop guy with a life, standing at the machine for a couple of days or so is the killer when it comes to long "for other people" jobs.

That £100 (ish) a pop price is well judged. Not so much to turn "Sheesh, thats expensive." into "Absolutely no poxy way.". The alternatives are either life is too short type things or do proper weld up, blast and repaint job which not only takes lots of time and effort but isn't that much cheaper when all is said and done unless you have all the gear and skills to hand.

Clive