G40 gearboxes weak. I'll hear no such thing!! Ha ha. Just read this thread. How ya doing our kid. Long time! Richie K (aka L680 TRP, White G40).
Squadron Leader! Good thanks mate! I still have a video of your old G with me in the back down the duel carriageway near PSD... H5LRW- Thanks The paint is a VHT crackle red, I forget who makes it, needs spraying on fairly thick, then baking off in the oven ideally. I waited until the Mrs was out.
[size=16pt]02J to PY[/size] The last post covered a brief decision on which gearbox I have chosen, and why. This will explain my solution to getting an 02J gearbox bolted to a G40 engine. Plate vs. Bellhousing Sorg have offered for a good number of years, the option to mate an 085 and 02A/J bellhousing together. This involves removing sections of the 085 (all 5 mounting locations and the starter housing) and welding them into the 02A/J bellhousing. This is no trivial task, the tolerances between dowel locations and the gearbox input shaft centreline must be <0.1mm to avoid premature wear on the spline. To add to the difficulty some of the later aluminium casings (02T) which could be used, have higher magnesium content, a very skilled task, and one outside of my ability. I also didnt like the thought of having a one off gearbox casing; Ive damaged two with failures previously, which was fine as they are easily and cheaply replaced. The cost of the Sorg option was roughly 900, plus a custom clutch (I dont include other custom parts as they are necessary for both adapter plate and bellhousing options, Ill cover them later). So, the Sorg option uses the following: - 085 Bellhousing - 02A/J Bellhousing - PY Flywheel - PY Starter Motor - Bespoke clutch (200mm with Golf spline) - Custom adapter for Golf to Polo Clutch release bearing Total for gearbox mounting, and clutch/flywheel hardware is ~ 1200. I was hoping to achieve everything for under 1k. Designing an adapter plate allowed me to use a standard 02J gearbox, with no modifications. I could choose to use a Golf flywheel, with an off-the shelf clutch. The main disadvantage of the adapter plate is the extra width it adds to the powertrain. In my case this is 10mm as I have a steel plate, some aluminium solutions in Germany add 15 to 25mm. On a Berg car this isnt an issue, but I didn't want to encroach on the wheel well too much (despite low offset wheels), I also wanted to keep the drivers side chassis leg stock. [size=16pt]Adapter Plate Design[/size] When designing the adapter plate there were several key considerations to think about: - Differential positioning remained the same for 085 and 02J installations, this gives the inboard CV joints sensible articulation, and does not necessitate the need to alter suspension geometry - Gearbox installation angle to be the same in the Polo as per Golf The above caveats dictate the angle of the engine. I exchanged a few e-mails with a German friend (who I owe a few beers!) regarding his installation, to check I was on the correct track. Although he has a Sadev box in his Polo now, hed previously done a similar conversion on another car. With that I set about measuring some of the components. Robin helped with gathering some figures greatly, so thanks to him- I guess he might end up with one of these at some point, so its in his interest The first design looked something like this: That achieved a differential centre line delta of 2mm(X), 26mm(Y) which I think is acceptable. To keep this diff centreline, and the gearbox installation angle, means canting the engine over from its original position. My measurements roughly showed the PY block sitting at 12 from the vertical. This would need to be nearer 40, clearly requiring some inlet/exhaust manifold modifications and some thought around the sump/oil pickup. Ill cover that at a later date as/when Ive thought about it! Clearly the box would require two new mounts (B mount, and C Mount) and with the new engine angle Id need to cut and shut the old A mount to increase the 12 stock to 40 requirement. I will cover this in a later update, as Im hoping to fit a smaller/lighter alternator too- so will end up making 3 new mounts, possibly adding a 4th to the subframe at the front. So, enough waffle about the principle! I mentioned previously a 10mm steel plate- Id decided on Steel for a number of reasons: - Plate would be thinner than an aluminium counterpart - Easier to machine than stainless - Can be nickel plated for corrosion resistance - Similar expansion rate to block - I can machine/drill/tap/weld it - Cheap! Aluminium offers a nice solution, but Id need to double the width and helicoil everything. Now, those of you with a background in engineering will probably be thinking, M12 thread, 10mm plate- yes I realise Im short of the 1xdiameter standard requirement, my excuses: - 10mm plate easy to come by (12mm was a longer lead time) - I like round numbers - 2 out of 5 fixings I can secure with an additional nut - Golf box uses 6 M12 securing locations, Polo has 5 M12 - I need to keep the plate diameter as small as possible for starter/flywheel engagement (a topic I will cover later)* - I can switch to a fine pitch thread if more engagement is required (standard M12x1.75 currently) [size=16pt]Adapter Plate Mockup[/size] With a design in the virtual world I needed to transfer it onto something physical. Most printers cant print 100% and suffer from shunt so a plotter is required. A good mate printed a few copies of the design off for me. I transferred this onto some 3mm ABS sheet I had knocking about, would be strong enough to bolt through with abit of support, and give me a decent idea of what needed to be modified. I still had the Polo starter motor mountings at that point as I wasnt sure what direction I wanted to go. Once Id cut it out roughly it got mounted in the car, the angles arent correct, but gave me a flavour of what to expect. Before I removed the engine and 085 gearbox I did various measurements so have a good idea of where the engine should sit indexed 40 round. With this done I did several more iterations of the design- to increase output shaft clearance (use the larger Mk4 Golf items) and to delete the Polo starter motor assembly, with some slight tweaking to hole locations, and double checking all 4 dowel dimensions, which are the most critical part. Although it looks like it would fit in that picture- the crank is hard up against the chassis leg, and has no pulley/FEAD on it, so need to move over another 35mm or so. Chassis must be cut...* Next up is the adapter plate manufacture, and the machine work required post water jet profiling. Ill save that until next week Cheers Pete
[size=16pt]Adapter Plate [/size] The last post covered the design of the adapter plate; this post covers the manufacture of it. The plate starts life as a 10mm thick piece of mild steel sheet roughly 400 x 400mm. The profile is then cut with a water jet, these are a nice alternative to laser cutting in my experience, accuracy is dependent on the machine, but typically 0.02mm I believe this also depends on the thickness of the part and hardness of the material. In an earlier post I mentioned the accuracy of clutch alignment had to be <0.1mm, I will cover this later in the post, but remember 0.1mm for now. So, first job was to get the plate cut out, once profiled it looked something like this: Fairly uninspiring, and not much use- the holes for the golf mounts have been sized for an M12 tap, hence the different sizes, Polo bolt pattern uses through bolts (bar one) so have clearance holes. Staring at a drawing, lots of tea, and using the Polo spacer plate helped get things sorted in my head: In my old unit I used to have a pillar drill, Ive since moved and had to get rid. This was the perfect excuse for PPP to purchase a drill so I can make these adapter plates; I doubt the profits from adapter plates will ever payback the cost of the drill mind* [size=16pt]Drill Time[/size] Axminster with a 16mm chuck (important): So, first job is to bolt the plate down and start lining things up. (The first job was actually the laborious task of getting the drill perfectly level, bolting it to the concrete floor, greasing it all and rebuilding it after dismantling it to securely mount it, but thats boring...) The drill is fitted with a conical shaped bit which allows a true center to be found. This is vital, we can assume the holes have been profiled accurately (0.02mm) so the biggest inaccuracy comes from me setting the drill correctly. Once the center has been found (i.e. the headstock isnt pushed in any direction when engaged with the hole) I then swapped to a 16mm slot drill for the dowels. I lightly scored the plate and measured the witness marks and convinced myself Id got everything true: Time to make some swarf: So, first hole cut. I wasnt happy with the drill, upon measuring the hole it was 16.38mm (Dowel OD is 16.0mm) so the dowel was like a dick in a shirt sleeve. The drill was chattering slightly, I decided to reduce the drill speed, use a different oil (0w40 fully synthetic from the other halfs car) and not be such a wimp. First Hole with dowel: Not good! Second hole with revised cutting speed, lubrication and a little more pressure resulted in 16.09mm, result! Second hole with dowel fitted: At this point I decided to measure various boxes I had laying around, I expected bang on 16.0mm from each, I was wrong. 16.08mm to 16.23mm- now some of my boxes have been on and off multiple times, but it was encouraging to know I could get the tolerance towards the tighter end of the spectrum. So, my target of <0.1mm from earlier was looking possible. I have no way of measuring this in an installed position, so I can only go from dowel locations. My tolerance stack is 0.09mm on the two Polo dowel holes, and 0.02mm on the Golf dowel holes. Although Im using the holes which had been profiled to locate my center find in, so assume I can get a Polo dowel to 0.11mm and a Golf dowel to 0.02mm. So not quite the <0.1mm original target, but without a milling machine I cant get this any better, plus its an improvement over some of my stock gearboxes! Onwards! [size=16pt]Countersink [/size] The plate bolts to the Polo block, this dictates the face must have countersunk fasteners, I used an A2 grade stainless M12 countersunk bolt. Quick check of the DIN/ISO standard gave me the angle of the countersink bit I needed to order (theyre usually 90 but worth checking). So big countersink bit arrived, these are known as snail shells apparently, they dont chatter and I've been really impressed with it, leaves a nice finish and swarf is easily moved. This process is the same as the slot drill, fit the center find, adjust, clamp the piece down, check, recheck, measure, adjust etc. Then countersink until the bolt fits flush! All the bolts holes requiring a thread are then tapped- I used the pillar drill to start them all off, ensuring the thread was perfectly square, worked a treat! [size=16pt]Post Machining [/size] Quick clean up and the plate looked like this (both sides shown): Youll notice theres a mark from a grinder- for some reason Id cocked up the measurement of the crank end oil seal housing. Bit of a pain, but it can be removed for mockup and the design revised before the next iteration. Few more close ups: [size=16pt]Dry Build[/size] Once Id done some measuring and checked the plate was straight and true, I then bolted it onto the Polo block. It is necessary to keep the standard plate so the dowel engagement is correct. Looks something like this: When bolted up the gearbox starts to look fairly large! You can also see the engine canted over to accommodate the driveshaft and output shaft clearance. In the next update Ill go over chassis modifications, cutting big holes out the leg, and hammering a square peg in a round hole. Although it will be fairly boring as its me making lots of measurements and swearing. I did get to play with my grinder though. Cheers Pete
Lots of detail there. Please keep the updates coming. How are you doing to secure the plate to the block ? The holes appear partially obscured by the gearbox ?
Hi Nige, indeed they are! The plate is secured to the polo block using 5 counter sunk M12 bolts, you can just make them out in this image: So, to assemble, the adapter plate is bolted to the block, followed by the flywheel/clutch, then the gearbox bolts to the adapter plate. Cheers Pete
Ah, yes. I see now. A bit of hindsight here, but wouldn`t it be better to test with a 15.8 drill or similar on a piece of scrap steel, that might then be the 16.0mm tight fit you`re after ? Saves drilling holes too big in the main plate. Like I said, a bit late now... lol
Nige, true enough! although I couldn't use a standard taper drill bit as the dowel hole needs to have a flat bottom, so I needed to buy a slot drill (flute?) for the mock-up I used a 16mm slot drill (as they're cheap, a pukka 15.8mm flute is circa 50) so I didn't want to buy one just to test. I think what I'll end up doing is paying a machine shop to mill these sections, as the depth is also fairly key, I don't have access to a surface table, but I think the face will also need grinding on both sides, so hopefully a few more machining operations won't break the bank. This also assumes the water jet cutting process (and my CAD) are accurate reference points... lol Still, if all else fails I'll hammer a golf lump in there too...
This about brings it up to date... Nothing much to update as I've been busy with other cars, managed a few hours on it this week, started to mock the A-mount up, and engine/box are currently in a position I'm fairly happy with. Other cars acting as distractions are: Some will recognize the yellow derby- It's taken a fair amount of recommissioning! Tow car is a B8 S4, 476PS and just shy of 600Nm... keeps me entertained for the daily commute. So, take some sheet steel, some CDS, grinder and file and one of these: Give you a load of random shaped pieces of metal: http://img.photobucket.com/albums/v251/Young_Un/C91EFA3D-E349-4BD7-AF77-F7A80F15DFF4_zpsuuuatbna. [img]http://img.photobucket.com/albums/v251/Young_Un/1FA9758B-3E19-4A28-AA15-DB2EA1FB36C0_zpsikhwjycn.jpg In situ looks something like this:
Makes sense. I`d have probably tried 16mm too, but it`s easy sat behind a keyboard commenting AFTER the event
Yeh, was watching that the other day. Looking through some old vids. Yours has come a long way since the old days of G60 blowers and the like! Loving the work!
Fabrication - Part 1 So, I havent been working on my Polo that much over the summer, but now with winter time, Im in the garage a few nights a week. Deadline is to have it running and MOT on the road by Easter next year, and use it as my wedding transport June 2015. On with some fabrication, it all fairly self explanatory, cardboard cut-out, transfer to steel, weld in steel... a few points I had to consider: - Retain subframe mounting points - Not spaceframing the front end (although with hindsight this may have been easier) - Fitting everything in with a reasonable static clearance (20mm+) - Driveshafts - Everything else, shifter mech, starter motor, clutch actuation, speedo cable, reverse light switch etc. The engine will be fairly stiffly mounted at 4 points, A and B mount on both longitudinals, these support the powertrain roughly in its desired installation angle, then C & D mounts to resist torque, Polo as standard doesnt use a front gearbox mount, but due to how I will mount the C mount, its necessary for this. So, after Id cut a fairly sizable hole, and made a Polo even more wobbly than usual, I got to welding bits in. For the next stage of welding Ill mount the subframe back up so the chassis is as per previous geometry. On to the pics... After cutting a big hole, I had a think about supports, my intentions was to mask as much as possible under the original chassis legs, it's neater and doesn't raise as many eyebrows come MOT time. So, this was the plan: Which obviously required lots of cardboard templates, measuring, cutting, and making of mess: And my least favorite part of fabrication, getting old seam sealer, paint etc off the chassis, deep joy. First on the list was to weld the two lengths of CDS together and insert them in the chassis, several tack/mock ups prior to this to ensure it was right: Hole saw used on the chassis that had tube passing through it, gave a nice tight fit, these have plates welded over the top to spread load. Before I welded the plates in I stitched the chassis leg where possible. And then next was to weld plates in around these tubes, tube poking through the upper chassis leg will be the last one to be completed. A quick tidy up of previous stitch welding on the chassis was done too: And then moved onto the NSF subframe mounting point, the access tubes are for the fixings, will try to find some plastic caps for them so they don't get full of crud. I ran out of gas at this point, so progress has halted up to here: All for now- please feel free to abuse my welding... it's not like riding a bike, I've still burnt myself several times, still I've remembered what Spanish underseal smells like when it's burning. Cheers Pete
No build thread, but I will have a vid of our recent outing at Blyton... don't usually have a Polo that lifts an inside front wheel in corners lol
