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Dec 17, 2021 18:06:42 GMT
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Meet Ruby. She is a standard 1970 MG Midget in flame red with a 1275 A-Series engine and 4 speed gearbox. She is lovely.  I can hear you from here Why on earth have you bought another Midget? It's not even a different colour - what are you thinking? What's wrong with the one you already have? etc etc etc Well strictly speaking I haven't. She has been bought by my company for properly testing a new 5 speed gearbox kit which I've been working on for a while now. It's the same Suzuki Jimny box I'm using in my car but will be mated to the original A-Series rather than the Micra engine.  I picked her up yesterday after viewing over the weekend. I've viewed several cars of very varied quality and condition but this one really stood out. In the early 90s the car was completely restored with a lot of new panels, respray and rebuilt engine and gearbox. Since then she seems to have covered only 7500 miles with history indicating she has clearly been well cared for. This is very apparent in how well she drives, putting my car to shame in terms of ride comfort, no doubt helped by semi elliptic springs and better seats. Also impressive is how much the BMC/BL engineers did in quite a short period of time taking the decidedly 50s feeling early cars and making them feel really quite modern. Wind up windows, inertia seatbelts, external door handles - maybe I just need to get with the times?  In the short term there are a few little jobs to carry out to sort some small niggles before I jump into the gearbox swap. Thanks for looking! James |
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Last Edit: Jan 29, 2022 19:29:48 GMT by metroman
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Dec 17, 2021 19:16:53 GMT
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Also impressive is how much the BMC/BL engineers did in quite a short period of time taking the decidedly 50s feeling early cars and making them feel really quite modern. Wind up windows, inertia seatbelts, external door handles - maybe I just need to get with the times? Nope, the side screen cars look so much better! The doors on the wind-up window cars look like what they are - an afterthought. Much more elbow room on the earlier cars too. Very much liking the sound of the gearbox to A Series engine conversion - will this be without any bodyshell mods? Also, will it be just for the 1275, or for the 948 too? |
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Dec 17, 2021 20:35:50 GMT
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No mods, just bolt in on the original mounts. Gear stick is in the original position too. There will be 948 and 1098 versions to come if there is demand, it just means having different flywheels and spigot bearings made to suit.
James
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Dec 19, 2021 14:27:35 GMT
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A great project. Not knowing anything about the Jimny gearbox, how do the gear ratios compare to the standard gearbox on the 1275 midget ? I have a friend who is restoring a 1275 Healey who is interested in your conversion. Keep updating your post. Will keep an eye open on how you get on.
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Dec 19, 2021 19:40:29 GMT
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Thanks rustymetal, I will keep the updates coming The ratios aren't that far off the ribcase until 4th, with a 0.86 overdrive 5th. Jumping between the two cars I am hard pressed to notice any difference at all on the road, if there is any lost potential performance the Suzuki box more than compensates with much faster changes. My 5 speed car still has a 4.2 final drive compared to the 3.9 in this car, but still manages to be much more civilised on motorways thanks to the 5th gear.  barrattengineering.co.uk/r7me/For more spirited / track use I have designed a close ratio gear set reusing as much of the original box as possible and retaining and full synchromesh.  James |
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Dec 19, 2021 20:30:07 GMT
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Looks a very short first on the suzuki box, I guess that's from it's 4x4 origins. That said you barely use the std first anyway so it pobably doesen't really notice. The short first might work well on the smaller engines particularly something heavy like the minor traveller or van.
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Dec 19, 2021 20:44:02 GMT
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The short first might work well on the smaller engines particularly something heavy like the minor traveller or van. IIRC, a 1098 Minor van had a 4.55:1 diff, for that very reason, compared to the regular Minor's 4.22:1. I have a feeling that the 948 Spridgets (& possibly Minor saloons too) were also 4.55:1. |
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Dec 19, 2021 20:53:51 GMT
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I suspect that is likely the case, on paper the ratios are not brilliant and I was concerned it may be noticeable in the car when building the prototype. As said, it isn't something I can really detect on the road and it certainly isn't something anyone who has test driven has commented on. Any prospective buyers are always invited to test drive and decide for themselves. The last thing I want to do is sell something that fails to meet expectations. The best 'factory' ratios I am aware of are from the 80s SJ410, which I am led to believe can be swapped into the newer and much more readily available case. This has a taller 1st and 5th with a 0.79:1 overdrive. For the effort involved I personally would be inclined to just swap the top gear, and only if you did a lot of motorway miles.  To clarify, the SJ410 case is externally completely different so not compatible at all with the kits I am developing. James |
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Dec 19, 2021 20:55:41 GMT
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The mm's had the 4.55 and the later saloons the 4.22, trouble with 4.55 is it's a bit short for modern road speeds, if the longer first allows you to fit a 4.22 it'd be better all round.
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Dec 19, 2021 21:01:43 GMT
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With the 0.86 5th gear cruise with a 4.55 diff would be equivalent to a 4 speed with a 3.9 final drive so you would likely get the best of both worlds
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Dec 19, 2021 22:28:13 GMT
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Also impressive is how much the BMC/BL engineers did in quite a short period of time taking the decidedly 50s feeling early cars and making them feel really quite modern. Wind up windows, inertia seatbelts, external door handles - maybe I just need to get with the times? Nope, the side screen cars look so much better! The doors on the wind-up window cars look like what they are - an afterthought. Much more elbow room on the earlier cars too. Very much liking the sound of the gearbox to A Series engine conversion - will this be without any bodyshell mods? Also, will it be just for the 1275, or for the 948 too? Maybe but as another owner of a MK2 sprite the same as the OP's I can see that when they were new the folding hood and the wind up window made them much more usable cars and that is what people wanted when they bought them new.
With my MK2 Sprite and also theFrogeye's i've had you have to find a petrol station or a convenient bridge to park under when it rains as assembling the hood and side screens even when well versed in it isn't a quick job.
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jimi
Club Retro Rides Member
Posts: 2,223 
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Dec 20, 2021 20:17:49 GMT
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I wouldn't have bought mine if it it had been an older one with sliding windows & a tent frame roof  Mine was a 1275 with a Downton Engineering stage II head, twin 11/2" SU's & a 3 branch extractor exhaust, wasn't slow   |
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Black is not a colour ! .... Its the absence of colour
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Dec 21, 2021 10:45:18 GMT
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Looking good metroman . Will keep an eye on your website for costs.
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Last Edit: Dec 21, 2021 10:46:08 GMT by rustymetal
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tofufi
South West
Posts: 1,462
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Dec 21, 2021 10:55:44 GMT
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Looking forward to seeing this progress onwards  Will the kit bolt straight in to a Minor as well as a Midget? (asking for a friend  ) |
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Dec 21, 2021 20:29:45 GMT
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tofufi - I believe it will fit a Minor, it will certainly bolt up to the engine and crossmember, the only unknown at this stage is clearance to the steering rack. I should be able to confirm either way soon. rustymetal - that's good to know, price wise it should come in less than an MGOC/Frontline Type 9 kit but probably not by as big a margin as I would have wanted. Material and machining prices are double what they were 12 months ago. That said it is bolt in so there is no labour / time spent cutting out chunks of chassis. Ref the early vs late cars I took both out back to back today for some demonstrations which was interesting. The later car is better as a 'car'. I personally prefer the early car, there is more charm and it feels like more of an event to drive (powertrain aside). However, if I had to have one as my only vehicle, daily use 365 days a year it would be the later one hands down. Progress normally makes things better but something is often lost in the process. The highly calibrated butt dyno says that torque curves are similar up to 3000/3500rpm, at which point the A-Series starts to drop away. The CG is only just coming on song at this point and things get fun! Both will be on the same dyno back to back soon. Thanks for looking James
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Dec 21, 2021 20:47:33 GMT
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For the minor steering rack you can cut a piece out of the bell housing like the minor has.
For the clutch, the rod set up for the minor would need to be converted to cable.
The minor is also very tight between the chassis legs, In standard form there is only a few mm of clearance to the starter and the clutch actuation arm on the gearbox will be close to the chassis legs and inboard side of the suspension eye bolt.
It would also need a new gearbox x member / gearbox mount, any modern gearbox with the layshaft under the mainshaft is not going to fit past it.4⁴
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Jan 29, 2022 19:28:40 GMT
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kevins - there is a traveller that has been converted with a Suzuki engine and gearbox, the box went in with no mods to the chassis and cleared the rack. The unknown between this build and my kits is the exact positioning so the box may need some material trimming. I have several Morris owners interested and have some empty gearbox cases I can lend out for build trials. Since the last update I've used the car a fair amount to make sure everything is in good order. Had a lovely blast over the downs in new years day with some friends  The engine was then serviced and checked over pretty carefully before both cars had some fun on a rolling road.   I was pretty pleased with the performance, although did expect the torque to hold up for another 500rpm or so. The car has been slightly modified with a nice K&N filter box with stub stacks and an LCB manifold, but I think the standard exhaust system is limiting their effectiveness at higher speeds. Torque beat factory numbers (if the rollers are perfectly calibrated!). The SUs do a great job of controlling the AFR.  The butt dyno wasn't far off in thinking torque would be similar to the CG13 car to 3000, after that it's a different story! This wasn't really the point of the project though. After several months of design, supplier issues, redesign and a lot of time spent I finally got the first gearbox kit together. So this happened.         I've got quite quick at this now! The weight of the A-Series definitely makes a difference though when manoeuvring the assembly out of the car. The ribcase was then removed, along with the flywheel and steel backplate and the kit laid out ready for a dummy build.  This is always a bit nerve racking as one-off parts are no cheap and there are always things that are missed or not perfect. I'm nowhere near skilled (or lucky) enough to get this right first time, the objective is to get everything good enough that errors can be resolved and fettled rather than parts scrapped. The key is to record it all so the error isn't repeated! The first error caused a bit of head scratching! Luckily workshop dog Ted sorted it out.  I had bought a 1275 backplate to take hole positions and profiles from, and been able to do a trial fit on a bare block without issue. So why didn't it fit over the oil seal? And why did the oil pump cover not fit in the hole? Simple - the plate I had copied was actually a 1098. D'oh. Thankfully it was a 'material on' problem so a bit of work with the powerfile got the clearance needed for the crank seal and a 1098 pump cover fitted just fine.  1275 plate overlaid onto the 1098 pattern new plate. A lot of work has gone into the clutch and flywheel for this conversion. The A-Series crankshaft flange protrudes a long way out from the back face of the block to allow the flywheel to clear the oil pump, which sits proud of the back face. This is no issue with the original gearbox which has a deep bellhousing with lots of space for a high clutch and release mechanism. The Suzuki box however has a very shallow bellhousing. This makes the box compact enough to fit in the MG with a 5th gear but leaves very little space for a clutch. The original clutch/flywheel is a no-go, and even re-drilling the flywheel for a more modern, lower profile clutch still leaves no space for a release bearing. Given the problems faced by MG owners the world over with failed release bearings this one was part I really did not want to try to design myself! The Suzuki part works and the Suzuki part stays! This meant the only option was a billet flywheel. A bonus is that the flywheel can be lightened, ending up at 4.3kg. The standard one is over 7kg. Space is at such a premium that I had to resort to countersunk screws to mount the flywheel. One of the locating dowels needed lightly dressing with a file but otherwise it bolts up just fine.   The assembly is a hybrid with a Nissan cover and 190mm Jimny disc and release bearing. The torque capacity is much higher than standard at over 150Nm so should be more than a match for pretty much any A-Series. With a small amount of fettling to make clearance for the starter motor it all bolted together nicely. The original inertia starter was another no-go. The system is just too bulky to fit without seriously compromising the structure of the gearbox so a high-torque unit has been used.  More to follow soon... Thanks for looking James
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hello i am doing this conversion on reliant 850 engine, which starter motor have you used that bolts straight on to the Suzuki bell housing?
Thanks
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Jul 30, 2023 16:28:31 GMT
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What year gearbox is this for? I believe that the Jimny was branded as a Samuri in the US. Will this be available in the US and is there an estimated price yet?
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following with interest, wondering if it would fit an A35.... cant see any reason why not.....
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Current fleet:
'58 A35 (half mine)
'67 11 window splitscreen vw (half mine)
'77 mini 1000 (not quite 1000 any more!!)
'86 Armstrong MT500
'89 XR4X4
'94 Corrado VR6
Some sort of sevenesque kit car (no age yet!!)
'01 Mondeo estate 2.0 (engine eventually destined for kit car!) - scrapped, engine only left!
'98 E300 estate, rusty but seemingly reliable, fast-ish tat hauler. eventual engine donor
A35 van, or whats left of it after it lived in a field for many years
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