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MG Midget and Sprite Technical - 5 speed options
| I am the original owner of a 1971 midget which is approaching 300,000 miles. The body has the original paint and the condition of the car is generally very close to new. 100,000 miles ago, I installed a Rivergate 5 speed with mixed results and have been wondering about the T9 as a potentially better solution. The Rivergate conversion has the following advantages:
-Great shifting -Quiet operation -The 5th overdrive allows for sustained running at today's highway speeds -Easy installation with no need to cut the crossmember or body. -100% spot on speedometer accuracy. Disadvantages: -Rough and noisy release bearing with limited life -Loose fitting needle bearings in adapted front U-Joint -No backup light switch provision -No provision for original Lucas starter with Bendix (must use gear reduction starter) -Replacement clutch disks fail when the springs pop out under certain load conditions. -Once you have a 5 speed in the Midget, going back to the ribcage is NOT an option If any T9 conversion owners can weigh in, I would appreciate comments and observations. I am also getting ready to rebuild the engine and am considering 9.75:1 pistons and a more enthusiastic cam. Especially with the 5th gear, a little extra umph is in order. Suggestions for the rebuild will also be appreciated. The car runs with the original S.U's and emission equipment. Thank you, Glen |
| Glenn Mallory |
| You could look into this conversion with the Suzuki Jimny gearbox https://barrattengineering.co.uk/cg-5-speed-spridget-kit/ . No chassis mods has to be a big plus. |
| David Billington |
| Glenn Great to hear from you and that is an amazing record of continued car use, care and upgrade. Will finding a Ford Type 9 gearbox in USA be tricky? Wasn’t it only sold in the Ford Sierra Merkur XR4Ti which was not produced in many numbers? Cheers Mike |
| M Wood |
| It pretty much comes down to money. If you have lots of it then the cost of importing a UK sourced and rebuilt T9 and the conversion parts/kit makes sense. With enough money you can up-spec the whole installation including choosing whatever 5th gear ratio you want.
Alternatively all the problems with the Rivergate 5 speed could almost certainly be solved with a lot less money that swapping to the T9 apart from perhaps the reversing light (you'd have to stick with a manual switch). Also I don't see using a gear reduction starter as being a disadvantage. The other thing to note is the T9 in stock form is an iron case box and heavier than the Datsun box. |
| Daniel |
| PS Really interesting to hear of your long-term experience with the Datsun 210 five speed gearbox Rivergate conversion. A gearbox I had wished was sold in the UK. Cheers Mike |
| M Wood |
| Moss sells a T9 conversion kit that includes a rebuilt box but yes, it certainly comes down to money. Is the clutch/release bearing setup on the T9 conversion durable and reliable? This seems to be the weak link in the Rivergate drivetrain. The carbon release bearing paired with the ribcase was not particularly durable either but it had a long throw and reasonable feel. It is odd but the carbon release set up on the B has never given me any problems. |
| Glenn Mallory |
| Glenn,
When I did my Datsun conversion, I went with the Morriservice kit. It uses the Datsun clutch and throw out bearing. I don't have as many miles on mine as you do but I haven't had any problems with it. The only thing that I had to do was get the flywheel drilled and tapped to accept the Datsun clutch. I also use my original starter. All I did for that was drill a hole in the bell housing to clear the Bendix gear. Since Paul, the owner of Morriservice died, it was taken over by Gerards Garage in San Francisco but that's been about 10 years ago so I don't know if he's still doing it. I know that he's got a web site with lots of information about the conversion among lots of other things. Might be worth looking into. Cheaper than buying the Moss kit. |
| Martin |
| Was there also a 5 speed Toyota conversion or have I dreamt that? Aside from the Triumph overdrive gearbox, is anyone aware of a separate overdrive unit for A series cars or is a lack of space the determining factor? |
| Jeremy MkIII |
| Jeremy, Toyota Starlet IITC. Unless I've dreamt it whichever Toyota box it was it was very strong as I'm sure you could also put it in the MGB GTV8(?). |
| Nigel Atkins |
| Glen,
I had very bad experiences of having a T9 because of where I bought it from and their installation work, most but not all of the problems related to the clutch and the release bearing. I had that swapped to a sports quality concentric slave clutch and even had problems with that - but that was at least a 2 in 20,000 units sold over 20 years problem. The T9 box as standard are more often than not from family sedan cars and they feel like they are too, fine but not sporty. You can get quick shift gear levers but over here at least those are for sports use and vibrate and rattle particularly at 5th gear speed and revs of about 70mph. Also a fast gear shift will beat the synchros often. Where a shorter shift does help is in cabin space, the standard gear lever with have your knuckles close to the dash for first and reverse will be very close to your right leg. I have a modified shortened standard Ford gear lever as a compromise (and even now still have two spare quick shift levers and uprated bearings for them). The standard plastic gear lever saddle soon wears giving more slop to the lever and shift feel but many owners would not notice because they're used to it. You can buy a (red) hardened gear lever saddle which is much better or a brass heavy duty saddle which are best avoided as they are for sports use. Standard 1st gears are very short/low(?) whatever the correct term is, fine for pulling away uphill when loaded but you are very soon into 2nd otherwise but you can get used to it and if the box is to be rebuilt a selection of 1st gear ratio. The box can be a little notchy in 1st and 2nd in cold weather but this can be improved by oil selection (depending on your oil beliefs). As standard there isn't a drain plug unless it's been added aftermarket. The box is heavy but the shorter prop from it gives a good firm feel to that, if not a light sports feel. Deeps on what speedo cog you have in the box but mine was 25/33.3% out, 30mph on the speedo was 40mph road speed. The speedo cable exists on the r/h/s of the box so I'm not sure what routing it would take for your car but you want smooth curves as much as possible, there are 90 degree take-off available I believe. I must say I was disappointed when I returned to Spridget ownership to find the Toyota box was no longer available as my father-in-law had a car with the box in the mid-80s and it didn't feel as slick as the boxes in the 1960s Fords I'd driven before. I've too much info to load up here on the T9 but you are welcome to it via the Archives here or email me and I will gladly send you want I have. |
| Nigel Atkins |
| Back in '96 I helped build a new Caterham Seven with the Type 9 box that had six forward gears. I wonder who made the gear cluster for that? Are they still available? |
| Peter Allen |
| The Caterham 6 speed box has 6th as 1:1 (and 5th is lower) so it has no advantage for motorway cruising and you can't use a super high diff ratio as a work around because 1st is really high.
The Toyota box was the T50 and now scarce and used a bellhousing cast in Australia. Apart from a 4 speed Ford box with an overdrive (in a transit minibus and not sure what else) there was once an overdrive unit with a yoke each end that had the potential to be bolted onto the back of most 4 speed boxes but fitting it in tunnel would have been interesting. I haven't said it for a while so may as well now: 'there are books with this stuff in'. |
| Daniel |
| Assuming a 1275 engine the Peter May Eng’ clutch roller release bearing will give reliability on a T9 conversion. The stock 1275 clutch cover should be used with the contact faceplate removed. My own roller release bearings are not suitable as they require the contact faceplates to be retained. Unfortunately a stock clutch cover will not allow the T9 1st motion shaft to pass through in this condition. |
| Alan Anstead |
| Thank you for the comments.
Martin, it seems that the Morriservice conversion with the 7" (instead of 6 1/2" clutch) was the preferred choice. 7" is actually a huge additional surface area when considered. It should be no problem having the flywheel drilled. I assume that the release bearing was also the B210 setup? The Rivergate application uses the original Midget clutch cover with the contact plate removed as Alan has mentioned for the T9 conversion. Some of the graininess in the pedal no doubt comes from the release bearing contacting the clutch fingers directly. The last time replaced the clutch, these "fingers" showed considerable and uneven wear to the point where I could imagine the bearing plowing through them as the ends break off for yet another spectacular red light failure. I wonder if the Morriservice conversion used the original slave cylinder? The Rivergate kit supplies a 7/8" bore cylinder to reduce clutch pedal effort. The adjustment setup is iffy, sometimes too close to the floor, sometimes with annoying vibrations and occasionally OK to inspire a bit of confidence. I appreciate the comments. They are helpful. Glenn |
| Glenn Mallory |
| Glenn,
Yes, the Morriservice conversion uses the 210 (not B210) release bearing. Just get a 79 to 81 clutch kit. All years use the same one and should come with the disc, pressure plate and bearing. It also uses the Spridget slave. Mine is the original 948 version and I've never had a problem with it other then the old age wearing out but that's to be expected. I did use the Datsun slave to fork rod since it has some nice adjustment to it. The kit came with a mounting braket for the slave which makes for a tight fit against the frame rail so I always get everything set up and adjusted before I reinstall the engine. |
| Martin |
| I may have this incorrect but I think Gerard of Gerard’s Garage may have retired. His website has some useful info on compatibility of standard Spridget parts, e.g. clutch covers, part numbers for standard gearboxes as well as on mods such as upgrading to disc brakes for early cars plus making hinges for grp fronts. Not sure if his Datsun gearbox info is still on there: https://www.gerardsgarage.com/ https://www.gerardsgarage.com/Garage/tech.htm Cheers Mike |
| M Wood |
| Glenn
Before you select your pistons and camshaft stop and think how you use your car and what you now want to achieve. Do you want to struggle with lumpy tickover in slow moving traffic and then take off like a wildcat say at 4k revs or perhaps you prefer a nice tickover and then a nice torquey delivery. Many will say read ‘Vizard’ tuning manual but whilst its basic engineering mat still be true camshaft design has come on strides in the intervening twenty odd years since publication. Look up A.C.Dodd on facebook. You can tell him your engine spec and he will probably suggest a camshaft of his own design. I have fitted a couple of his RT (road torque) camshafts to my car club members cars having optimised the CR at 9:1 and the owners are really happy. Several others have followed suit. However another member went for his RS ( Road Sports) camshaft but goodness knows why as his driving is never sporty. Swiftune and M.E.D. To name but two also supply more modern camshafts. |
| Alan Anstead |
| Thank you Alan. I need to put together the best compression ratio/cam combination for current highway conditions in this part of the world.
Highway speed limits are 75 MPH but traffic normally moves between 80 - 85 MPH without penalty. Maneuvering in the Midget in 5th gear at speeds above 70 MPH is difficult but often necessary in traffic. Being able to accelerate to 80 MPH for lane changes or to remain in the current is a safety matter. Spritely response at 4000 RPM is the target, at 5,000 Ft. above sea level altitude. I note availability of 9.75:1 pistons but do not want to get into a lumpy idle cam. Since the engine is tired, this is the time to get it right. I was 16 when I got the car new and 51 years later get pretty sore pulling the engine and mucking around under the car. The original engine lasted for 170,000 miles before getting weary. The speed limit in the U.S. during most of those years was 55 MPH, which no doubt contributed to engine life. There have been two rebuilds since with lousy surfacing of the block on the last rebuild. It was bored to .020 over with a crank grind to .010. I have had head gasket sealing problems and note the poor machine work on the block. There is no racing or hot-off-the-line requirement, only to be able to keep up in highway traffic. A 100,000 engine life would also be good, especially if a way to keep the cam pristine can be found. High ZDDP content oils and ZDDP additives have not been up to the task. SD and SE oils were the trick. |
| Glenn Mallory |
| Martin, looking at Datsun clutch kits online, it appears that the original set up had the release bearing depressing the ends of the fingers directly without a bearing pad as was used in the original Midget configuration. The Rivergate release bearing depresses the fingers directly but not not where they end. Pushing them midstream probably affects the pedal stroke and the feel, especially since the BMC clutch was designed to engage from the pad.
The Datsun clutch kit is so inexpensive that there is no reason not to order one to check the fit. Thank you for the information as I had no idea that there was a configuration for the Midget that used the Datsun clutch. |
| Glenn Mallory |
| Glenn,
The Datsun clutch release bearing isn't a carbon one. It's a roller bearing. Hence, no bearing pad. The only thing you might have to get besides the clutch kit are the release bearing retaining clips. I find that using the original Datsun setup seems to work better since, once you've drilled the flywheel to accept the pressure plate, matches the gearbox like it was designed to. When I had my engine rebuilt, I had them install an APT 266 cam. (APTFast.com). They're in southern California and they grind their own cams. It pulls well from 1500 RPM and so far I'm happy with it. One more option to look consider. |
| Martin |
| Don't forget. If the clutch fingers are flat you need a release bearing with a rounded profile. If the ends of the fingers are shaped (rounded contact) you need a release bearing with a flat profile. Rob |
| MG Moneypit |
| Rob, That's one of the reasons I like using the Datsun clutch kit, a matching set. No special mix and match parts to find. |
| Martin |
| I emailed Gerard of Gerrard’s Garage and he replied yesterday that he may still have some parts related to the Datsun gearbox conversion, but not complete kits - should be an email address on his website. Cheers Mike |
| M Wood |
| Mike, Did he happen to mention who might have taken over for him? Or is it that no one does kits any more other than Rivergate?? |
| Martin |
| Mike, If you could share Gerard's E-mail address, I would appreciate it. I didn't find it on the remnants of their website. I will contact them and ask about flywheel drilling, slave cylinder rod, etc. Thank you, Glenn |
| Glenn Mallory |
| Hi Glenn
I have asked Gerard what is the best way to contact him to ask about any remaining parts and pointed him in the direction of this BBS thread. I did also forward him your email address as it is on your public posting on this thread. Martin, I will also ask about who, if anyone, has picked up supplying this conversion. It is pure chance that I had Gerard’s email address from when I bought some of his manufactured MkII Sprite disc brake master cylinder pushrods a decade ago. Glenn - have you also tried posting on the MG Experience MG Midget forum which seems to have more USA based members including those using Datsun gearbox conversions: https://www.mgexp.com/forum/mg-midget-forum.3/gerards-garage-or-rivergate.2452313/page-2 [Gerard posted on that thread) Cheers Mike |
| M Wood |
| Glenn
Guess you might have seen this: https://www.ahexp.com/forum/the-sprite-forum.6/datsun-5-speed-question.200318/ If you do decide to go Ford Type 9 gearbox, I wonder if the Caterham, Morgan or Westfield communities and suppliers in the USA might be a source? If it were not for the expense, a good option might be to source a secondhand Ford Sierra Type 9 gearbox (of the preferred spec) in the UK and get someone like BGH Geartech to rebuild it and ship it to you: http://www.bghgeartech.co.uk/html/5_speed.html Daniel Stapleton’s book has useful info on the Ford Type 9 conversion as well as Datsun info you know. https://www.amazon.com/gp/product/B00GHPFSFO/ref=dbs_a_def_rwt_hsch_vapi_tkin_p1_i0 Not sure if Daniel is currently updating his book (or just has), but your long-term perspectives of the conversion is very useful. Some of the experienced Ford Type 9 gearbox conversion gurus post on here. There was a very useful more detailed discussion a few years ago between Glenn, Alan and others on building tractable engines which had also popped up in this thread - I’ll see if I can find it as I copied it for future reference and engine building. Cheers Mike |
| M Wood |
Another engine for a Masc member. Fitted with an A.C.Dodd RT camshaft.
 |
| Alan Anstead |
| There was some useful info on an earlier thread: https://mg-cars.org.uk/cgi-bin/or17?runprog=mgbbs&mode=archiveth&archiveyear=97_2020.dat&access=&subject=97&subjectar=97&source=T&thread=20200814182542225669 Cheers Mike |
| M Wood |
| Glenn, I sm very interested in your comments and the pros and cons of the Rivergate conversion, as we have the Datsun box in one of our Midgets - though with a bespoke conversion by PO.
Although the lack of a reverse light switch is an irritation, it can be got round and I can honestly say that the other items you list haven't been an issue other than when we bought the car it had a history of broken clutch plates. This was traced to the backplate being 1mm off-centre. Fixed that, and have done 30000 miles since with no issues - all on a fairly well tweaked engine (286 cam, good head job with big valves, 11:1cr etc) and used vigorously in track days and autotests. Release bearing hasnt been an issue. Uses cable actuation as per Datsun. PO cut a hole in the bellhousing for the starter bendix. No prop uj issues either. Having tried a few, the Datsun box is my pick, especially as the crossmember remains intact. It is a key component of structural rigidity. We compensated for having to remove it for the k series conversion's Supra box by ringframing the tunnel, but it was a fairly major bit of bodywork. The Toyota Starlet box also fits without removing the crossmber, and like the Datsun has the gear lever in the right place. But it is a little bulkier and very tight to remove - the crank pulley must come off to get clearance. Otherwise a good conversion. One disadvantage of these small in-line 5 speeds is that donor vehicles are ageing and numbers dwindling, so they are getting hard to find. Or should I say they are hard to come by here in NZ, I would be interested to know about elsewhere. (with aopologies for fat fingered typos on the phone keyboard) |
| Paul Walbran |
| Paul, The Datsun boxes are like hens teeth here in the States. At least up here in Washington state. You might be able to find some in wrecking yards in places like Montana and the Dakotas but it would take a lot of searching. As far as the cable actuation goes, mine came with a slave cylinder and push rod which I used with my original slave. |
| Martin |
| Thank you Mike for sending the link to my earlier thread. I have continued to drive the car in its anemic state. It is reliable and runs well enough but doesn't really run well enough. During Covid, it didn't get to travel much.
Thank you Paul for your observations. I have a microswitch rigged for reverse lights and it works off and on. Obviously this isn't critical. I initially ran the Bendix drive starter but had trouble with dirt and grit fouling it on extended trips since it was exposed. I broke the case of my first Datsun box over tightening the drain plug so I installed the reduction starter motor on the second unit. The Isuzu Trooper reduction starter works well enough but it turns slowly compared to the original Lucas unit. It grinds and whines to a start instead of having that instant response that was characteristic of the A. But considering everything, the Trooper starter is a keeper. The problem I had with the Rivergate clutch disks was that the springs would pop out shifting from forth into fifth under load. I had two of them fail this way on the same expressway flyover. The failure breaks the neck off the front bearing cap over the main drive gear. Shifting without a clutch feels like it is harder on the Datsun transmission than it was when the clutch would fail on the original ribcase transmission so it isn't good. The original Rivergate disk had rubber inserts instead of springs so using an early disk is the fix. These disks are no longer available through Rivergate. I will have the flywheel drilled for an original Datsun clutch and install a clutch kit that includes the release bearing, cover and disk. It has occurred to me that centering the new cover exactly will be critical and hopefully the machinist can manage this when drilling the new holes. |
| Glenn Mallory |
| Glenn, One thing to remember when drilling the flywheel, the pattern for the mounting holes on the Datsun clutch isn't symmetrical. It only lines up one way. The same for the little alignment pins. They're all on the same diameter but not equally spaced on that diameter. |
| Martin |
| Glenn, for what it is worth (given that what is available here msy not be the same with you) the clutch plate we use is a Peugot 205 one. Not sure which flavour of 205, I have only the part numbet ascribed to it by a local clutch specislist. This plate has given us no trouble. Which is a very dangerous thing to say! |
| Paul Walbran |
| The Suzuki R7ME gearbox conversion kit now has a price. https://barrattengineering.co.uk/prices/ |
| MG Moneypit |
| The Suzuki R7ME gearbox kit now has a price. https://barrattengineering.co.uk/prices/ |
| MG Moneypit |
This thread was discussed between 08/02/2022 and 15/02/2022
MG Midget and Sprite Technical index
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