Adapting a gearbox to an engine that it doesn't belong to

[bahaimus]

So, I've got this Merc engine for my Merc car. The overwhelming majority of these cars/engines came with automagic boxes and very few with manuals. The fairly rare (especially outside of a car - like from a wrecker) version of the manual box in Australia is pretty shit. Not to be considered.

There was a nicer close ratio version in the Cosworth 190e. But these were never sold in Australia, so I'd have to source one from overseas and I reckon I'd be looking at $2k+ by the time I got it landed. On top of that I would actually need to convince an overseas seller to package it up nicely (like in a crate, not just on a pallet) so it arrived in tact and I'd need flywheel, linkages, master and slave etc. Then, if I get it here and its fucked, well where would I find another one?

Therefore, I'd like to consider the possibility of adapting a locally available, decent gearbox.

Some questions:-

Anyone know of an engineering shop in Brisbane who might tackle such a job without making me feel like I'd gone 12 rounds as Tyson's jail bitch? I can provide an existing auto box for bellhousing dissection and an engine out of the car.

I've seen a few different ways of doing this - what's better or is it a case by case situation:
- Make an adapter plate for the bellhousing to block mounting - how do you deal with starter motor position?
- Cut two bellhousing and weld them together - effective perhaps, but certainly not pretty
- Use existing bellhousing and make an adapter to fit to gearbox - Need a gearbox with removable bellhousing and similar from original bellhousing

Say I used an automatic bellhousing, this obviously has no allowance for clutch slave cylinder and clutch fork - I've seen some concentric throwout bearings though (slave and bearing combined), could make use of that. Here are a couple of pics of the existing auto box (ignore the wtf).
http://i302.photobucket.com/albums/nn98/bahaimus/p1010176mediumpw7.jpg
http://i302.photobucket.com/albums/nn98/bahaimus/p1010185mediumhb0.jpg
Unfortunately, it is a one piece front housing, but the picture inside the bellhousing lends me some hope I could cut the bell off and use it in the adapter.

Is it an absolute imperative that the input shaft of the box sit inside the spigot bearing in the back of the crank? Why don't auto's seem to do this? Manual Nissan Micra's don't either.

Say I was to attempt the design of an adapter plate myself, how would I go about determining the shaft locations accurately so I could mate one component to another?

Engine will be a 3ltr twin cam current rating around 170kw (at engine) and 270nm. Will probably(?) stay NA, maybe some breathing mods for a bit more power. Estimate of loaded car weight inc driver - say 1300kgs. What would be a good box to consider? If I'm going to go to the effort, might as well consider all options. Would one of those Aisin 6sp boxes be alright like in the IS200, S15, MX5, S2000? Not sure how much they are worth though and I've heard that some uprated S15's kill them, but they'd be making quite a bit more torque I'd be guessing. But by the same token, a V160/161 Getrag would be far too expensive. Even an R154 at ~$1500 just for the box would be more than I'd want to spend.

I know flywheel and clutch choices are a further consideration, but I'm less worried about that.

[Glenno]

To keep things easier your probably looking at having a custom flywheel made so that you can use a common performance clutch suited to the box. This also means you can make up custom postions further back for the flywheel face ect as well. Usually using the pressure plate ring gear for the starter.

Input shaft in the spigot bearing is a very good idea stops the relatively long input shaft flopping around and bending particulary when the clutch decides to grip slightly off centre (single shear is bad mokay). Remeber the clutch centre is hanging right on the end of the longish input shaft and a manual micra makes 3hp and 1ft/lb or torque.

Measuring things is all about your point of reference which in any case is going to be the centrline of the input shaft and crank.

Is the starter on the engine side or the box side?

Concentric hyrdaulic throwout bearings are pretty common things pretty sure a lot of SAAB's had them actually I remember buying one for a hollinger setup and it was a SAAB part.


Adaptor plate is nice if you can do it I have seen various things done to cater for the input shaft not reaching the spigot including, maching the block or the gearbox face (or both) to compensate for the plate thickness and a custom flywheel with the spigot and friction face further back.

[bahaimus]

Thanks Glenno.

Starter is on the engine side.

[Glenno]

No worries,

I suspect someone like TK might have a lot better input on somethign like this though particualry in regard to what works best and what is a less than ideal solution.

[Herve Villecha]

GTiRs don't use a spigot either so it's not just pissy low powered shitboxes that leave them out.

[PHULL]

just for some inspiration I have some other ideas.

What about a FC Series 4/5 RX7 gearbox, they seem pretty good. or a Supra 5 speed.

since your merc gearbox has an integral bell housing you will need to use one off another gearbox. so you will need a adaptor plate to match up the chosen gearobx and bellhousing to the engine block. Good idea is to make a dumby one out of wood and get somone cut it for you ( steel or aluminium).

research what kind of clutch actulation your car requires when it had the clutch fitted from factory. ( is it cable or hydraulic?)

Is your chosen gearbox arm actulated (push or Pull) or the saab one like above. the saab one will need the throwout bearing correctly spaced from the clutch fingers, (wrong clearane and it may not operate the clutch correctly due to too much or too little travel. and a arm actulatred one willbe able to adjust this clearance externally without having to dismantel the entire setup to adjust the clutch slave cylinder

[dsm2002]

I understand the Merc Cosworth 190e used the Getrag 265/5 ... the same one as the E30 M3. These boxes and the earlier 262CR or OD boxes are not uncommon in OZ. Dick Prince who used to run the Ovlov 760 in IPRA had a pattern for these - Link (http://www.ovlov.net/page.php?page_name=gearbox). It may be possible to weld this adapter to the back of a suitable bellhousing. The ovberdrive 262s and 265s are cheaper than the CR box.

http://www.ovlov.net/images/gearboxadaptorlarge.jpg

[bahaimus]

just for some inspiration I have some other ideas.

What about a FC Series 4/5 RX7 gearbox, they seem pretty good. or a Supra 5 speed.

since your merc gearbox has an integral bell housing you will need to use one off another gearbox. so you will need a adaptor plate to match up the chosen gearobx and bellhousing to the engine block. Good idea is to make a dumby one out of wood and get somone cut it for you ( steel or aluminium).

research what kind of clutch actulation your car requires when it had the clutch fitted from factory. ( is it cable or hydraulic?)

Is your chosen gearbox arm actulated (push or Pull) or the saab one like above. the saab one will need the throwout bearing correctly spaced from the clutch fingers, (wrong clearane and it may not operate the clutch correctly due to too much or too little travel. and a arm actulatred one willbe able to adjust this clearance externally without having to dismantel the entire setup to adjust the clutch slave cylinder

The idea of the Mazda box had crossed my mind, they seem to be readily available and fairly cheap.

I don't have the auto out of the car yet, but looking at this picture I was hoping that I might be able to obtain a flat mounting surface and utilise the bolt holes by slicing the back of the gearbox housing off the "bell".
http://i302.photobucket.com/albums/nn98/bahaimus/p1010185mediumhb0.jpg

Factory manuals had hydraulic clutch and push actuated by an arm.


I understand the Merc Cosworth 190e used the Getrag 265/5 ... the same one as the E30 M3. These boxes and the earlier 262CR or OD boxes are not uncommon in OZ. Dick Prince who used to run the Ovlov 760 in IPRA had a pattern for these - Link (http://www.ovlov.net/page.php?page_name=gearbox). It may be possible to weld this adapter to the back of a suitable bellhousing. The ovberdrive 262s and 265s are cheaper than the CR box.

http://www.ovlov.net/images/gearboxadaptorlarge.jpg

From previously dalliances with BM's I was under the impression that the majority of Getrag boxes do not have a separate bellhousing much like the 265/5 in the Cossie and the 260 that I had in my E30. But I'll do a bit more research.

[tim510]

id look at a VG30DE box. nissan R30a gearset (same as RB25/RB26) and cheap as.

but you'd need to make and adapter plate or join the bellhousings

[bahaimus]

Do they have a detachable bellhousing?

[60TJZ]

I would have a thought a w58 Supra box,
They are cheap around 400-500, will hold power upto about 300RWHP.
THen contact dellows (they arent the greatest people at what they do) but it will get the job done. Tell them the motor and the gear box they make up a bellhousing to suit, they will provide a clutch fork and what slave cylinder to use. (around $500) then get a gearbox mount made up and tales shaft to suit.

[bahaimus]

Mazda box looks too long and a lot of mucking around to move the shifter forwards

http://i302.photobucket.com/albums/nn98/bahaimus/cfe0_1.jpg


I would have a thought a w58 Supra box,
They are cheap around 400-500, will hold power upto about 300RWHP.
THen contact dellows (they arent the greatest people at what they do) but it will get the job done. Tell them the motor and the gear box they make up a bellhousing to suit, they will provide a clutch fork and what slave cylinder to use. (around $500) then get a gearbox mount made up and tales shaft to suit.

Yeah, w58 probably offers a lot of flexibility in options.

I wonder what criteria Dellow would have in order to make up a new bellhousing

[Glenno]

I wonder what criteria Dellow would have in order to make up a new bellhousing


You probably wouldn't want it if they made it anyway even if you gave them exact measurments and tolerances.

[bahaimus]

You probably wouldn't want it if they made it anyway even if you gave them exact measurments and tolerances.

Yeah, there is that reputational element of concern as well.....

[60TJZ]

I have seen there work.. dont get me wrong it works, but
1. it wasnt pretty
2. Was expensive becasue you have to use there stuff (ie clutch fork/ throw out bearing etc)
3. was not my anymean user friendly

[dsm2002]

From previously dalliances with BM's I was under the impression that the majority of Getrag boxes do not have a separate bellhousing much like the 265/5 in the Cossie and the 260 that I had in my E30. But I'll do a bit more research.


The 262/265 boxes in E30 M3 and the 5 series and 6 series M30 Big sixes of the 1970s and early 1980s had separate bellhousings. the later 260 has an integral bellhousing. The 262/265s are getting old and some newer Jap boxes maybe better/cheaper/more available.

[aaron_hogan]

Mazda box looks too long and a lot of mucking around to move the shifter forwards

http://i302.photobucket.com/albums/nn98/bahaimus/cfe0_1.jpg



actually that is the easy part. blokes mod the shifter to fit these into every old mazda. Its just a case of lopping off the selector shaft and moving the shifter forward to the next set of bolt holes. then drilling and tapping the shaft to suit the new position. you then make up a brace out of plate that bolts to the side of the shifter housing. I've seen my mate do the job in 30 mins, mid you he has done this job many many times.

[Madhatr]

cut the first 3 inches of belhousing off the auto box, then weld it to the belhousing of your intended gearbox. There is an escort with an SR running a VG30 box downstairs with this exact thing done, works fine and supported nearly 600hp before the car was rebuilt.

The trick is to get everything centred and lined up properly, a shit job here can cause a range of things from thrust bearings, input shafts, clutches.

265's can come in 4 piece config, as said you need the early boxes with the extension housing on the rear. If they dont have the housing, they are the newer boxes and will be a 1 piece case/belhousing. Anything from the big 6's prior to about 1984 should find you a seperate belhousing, ive got a 265 here from a 633csi along with the M20 housing from an earlier 245. Simply bolted one to the other and its good to go with a new clutch.

http://www.rd-motorsport.net/images/stories/fun%20stuff/265_2.jpg

http://www.rd-motorsport.net/images/stories/fun%20stuff/265_1.jpg

Can be a bit exy even for the OD models here though, manual M30's are pretty hard to find in general, especially so in aus. Id probably expect to be charged up to a grand for one, otherwise you can pick them up from the states for about $200-$400 depending on condition.

[jmac]

tiny comment here - I'd be _careful_ about using rotary boxes. In general, they (esp with boost) make very decent hp, but the torque is (relative to a piston engine) no so monumental, and apart from shock loading, there are two things which destroy a box (and the higher either is, the more the risk) and they are, in order, torque and vehicle mass.

Given that this is essentially a one off type of conversion, you'd want to make _bloody_ sure that the box you choose is more than capable of the job, otherwise you'll soon be chasing up a second custom bellhousing/adapter to suit a more robust gearbox..

The actual nuts and bolts of a conversion isn't so overwhelmingly sky high in price. It's a long shot, but it wouldn't hurt to look at a euro forum with a wtb advert for a completely stuffed factory manual box, from which you'd take the bellhousing, and not need the rest.

Even if you get an engineering place (and a good one) to do the adaption, you still ought to run a dial indcator bolted to the flywheel/crank tail and run it around the base 'sleeve' (where the clutch throwout goes, or another round gearbox suitable reference point) and double check crank to gearbox axis alignment. Even the best engineering shop (well most) will only get it within a few thou. There's some debate as to max allowable runout, but my personal take is any more than 1.5thou and you are looking for trouble down the road, esp in high torque/hard usage conditions. Thankfully, this is easy to correct, you take the existing box, and get some offset locator dowels to insert in the back of the block, that shift the box 1-2 (or howevermany thou is required) in whatever direction you need.

Reason I bring this up? On hemis, the factory sent em out with a bw35 auto, with very few exceptions. Some came with a torqueflite, but not many. The obvious choice, if a t/f block is not available, is the torqueflite conversion. A certain mopar vendor claims all sorts of magic and voodoo reasons as toi why it 'never works' but the tool _clearly_ was too retarded (when he attempted and failed at it) to even comprehend the need, let alone undertake the steps, for close crank/trans alignment. In fairness, the 'issue' is further compounded by the fact that some torqueflites left the factory with the front pump centreline about 3thou off centre vs the rest of the trans geartrain axis centreline! Shit happens I guess.

You arguably (assuming you have a sprung centred clutch, not a solid one) have a little more tolerance safely on a manual vs an auto, but I'd personally not want to go outside of 2thou for a manual. But that's just me.

If you were in Vic, i could give you a couple of places you could take it that won't charge extortion like fees (not dirt cheap either mind you) but their work is top notch.

[Shifty]

There is a reason people ditch Mazda boxes... they're shit. They're bad to shift with, get stuck in gear, etc, and aren't generally that strong. Some people have luck with them, but as a general rule that's more about luck than them being a good box.

I would use a W5x (cheap, strong, readily available, beautiful to drive with, big overdrive, various shifter positions available, strong aftermarket, etc)... and R154 is another option but you're starting to talk real money for the box then, and you can't just grab another one for a few hundred bucks and bang it in... Tim is also on the money with the late Nissan boxes but AFAIK they're not a detachable bellhousing which is a pain if you break one and have to get another... at least with a W5x you can just drop it out, undo eight(ish) bolts and swap the bellhousing onto the new box.

Shame you didn't mention this two weeks ago as I only just gave one away and it would have been perfect for your measurements etc.

[bahaimus]

I've got a lead on a 6sp Merc box, here in Australia, that anecdotal evidence suggests will bolt onto my engine (flywheel and clutch are a potentially a very different matter...).

Unfortunately, it is from one of the most notorious chargers in the Euro wrecking game in Aus. But, even at the initial quote of $2750, it is probably competitive with the sorts of costs I'd be up for with an adapter. Plus I'd end up with a factory type solution.

Hmmm - I'll have to see what sort of price they come back with....

[bahaimus]

Bought this. Fuck me, feels like a lot of money to drop just on a second hand gearbox. Hope it fits.....