Bell Housing Kits and Associated Parts – Subaru Powered VW Conversion

Price: from £468.33 GBP + VAT (£562)

Our bell housing kits suit joining just about every Subaru EJ, EG, EZ, EE, FA and FB series Subaru engine, from manual or automatic Subaru models, to all VW 002, 091 and 094 manual transaxles. i.e. all the rear engined VW bus and Type 4 models with manual gearboxes. They do so using the Subaru flywheel, clutch and starter motor (including all the ‘pull to release’ clutch models), solving all the problems inherent to using ‘adaptor plate and flywheel’ kits with original VW bell housings. Prior to our designing them back in 2002, adaptor plate / flywheel kits were the only way to join Subaru engines to VW gearboxes, but which force you to use unsuitable clutches and starter motors.

Subaru use many different clutch and flywheel types, and covering all of them with one bell housing kit is not possible, so we make versions to suit each clutch type. Most of our bell housing kits can be converted to suit other Subaru clutch types by purchasing additional parts – . i.e. without having to change the entire kit. There is a version of each bell housing kit to suit each VW gearbox input shaft type.

See The Advantages of our Bell Housings for more details.
See Bell Housing FAQ for answers to some common questions.

VW Bell Housing Kits for Subaru ‘push to release’ Clutch, Single Mass Flywheel, Normally Aspirated EJ or FA Series Engines (part numbers 800-00001 and 800-00021):

The bell housing kits required by a very large majority of customers. They suit all normal use applications with 225 – 230mm ‘push to release’ clutches’ used with the EJ series engines, with up to around 170 bhp, and use a VW 228mm clutch disc.

Designed for use with the following Subaru flywheel and clutches:

Flywheel:	From:	To:	Induction:	Subaru models:	Engines:
single mass, flat faced, 268mm clutch PCD	MY90	MY99	normally aspirated	L, I, F	EJ20, EJ22, EJ25
single mass, flat faced, 268mm clutch PCD	MY00	MY07	normally aspirated	I, F	EJ20, EJ22, EJ25
single mass, flat faced, 268mm clutch PCD	MY00	onwards	normally aspirated	L **	EJ20, EJ25
single mass, flat faced, 268mm clutch PCD	MY08	MY14 *	normally aspirated	various	EJ20, EJ25
single mass, flat faced, 254mm clutch PCD	MY90	MY94 *	normally aspirated	L	EJ18
single mass, flat faced, 268mm clutch PCD	MY12	onwards	normally aspirated	GT86 / BRZ	FA20 / 4U-GSE

L= Legacy / Liberty, I = Impreza, F = Forester

The release bearing(s) and diaphragm spring centre that this bell housing kit works with are as below. No other types, including the thinner version of this bearing design are suitable (clutch parts not included):

Versions of this kit are available for both the long and short VW gearbox input shafts. The long gearbox input shaft was used in type 4 engined bays / T2’s and petrol T25 / T3 / Vanagons). They are 298mm long overall, and have a nominal 43.5mm protruding past the engine end of the clutch spline in to the pilot (or spigot) bearing. The short gearbox input shaft was used in type 1 engined bays / T2’s, diesel T25 / T3 / Vanagons and the CT 1.6 petrol engined T25 / T3 / Vanagon). They are 286mm long overall, and have a nominal 31.5mm protruding past the engine end of the clutch spline in to the pilot (or spigot) bearing.

We can also do a version of these kits for use with the BRZ / GT86 230mm clutch and it’s matching flywheel, on either EJ or FA series engines. They don’t use the same flywheel as the EJ series ‘push to release’ clutches though – they use the 254mm PCD flywheel from the GT86 / BRZ with a 2mm step (which is physically interchangeable with the flywheel from the ‘push to release’ MY05 onwards low powered turbo pull to release application, but considerably lower inertia / ‘lighter’). These also use the VW 228mm clutch disc. However, note that the standard GT86 / BRZ clutch does not have a very high torque capacity – around 84% of that of the standard Subaru / Exedy EJ25 clutch, or just 73% of that of the EJ25 clutch that we stock. For almost all VW applications, you’re better off using the 268mm flat faced single mass EJ series flywheel. Far more clutches are available for them, and they were used in many more Subaru models.

If you’re interested in this kit, you may also be interested in the following associated parts:

050-00025 Clutch release shaft
800-00024 Clutch release shaft fitting kit
100-00073 Release shaft arm (hydraulic clutch)
100-00072 Release shaft arm (cable clutch)
100-00075 Return spring (cable clutch)
100-00076 Spring seat (cable clutch)
800-00053 Slave cylinder bracket (our reproduction of the VW petrol bracket)
800-00046 Bell Housing to engine bolt set – Phase I (2 bolts)
800-00062 Bell Housing to engine bolt set – Phase II (6 bolts)
040-00032 Lower engine to bell housing stud (per pair)
040-00043 Replacement input shaft oil seal
800-00021 Clutch kit (good for up to around 170 bhp in normal use applications)
100-00071 Flywheel
800-00042 Flywheel bolt set
100-00040 Flywheel cover

VW Bell Housing Kits for Subaru ‘pull to release’ Clutch, Single Mass Flywheel, Turbo EJ Series or 6 Cylinder Normally Aspirated Engines (part numbers 800-00003 and 800-00052):

Originally all of the Subaru turbo models used ‘pull to release’ clutches. Later only the higher powered models (more than about 250 bhp) used them (with the lower powered turbo models changing to a different ‘push to release’ clutch – see below for a bell housing kit for them) did. These are the bell housing kits required for the 225 and 230mm ‘pull to release’ clutches. They suit turbo or 6 cylinder normally aspirated (EZ30 or EG33) normal use applications with 225 – 230mm ‘push to release’ clutches’ and up to around 180 bhp (with the right clutch pressure plate), and use a VW 228mm clutch disc. Their clutches can only be hydraulically actuated (not cable), using the original VW T25 / T3 / Vanagon slave cylinder. Modification to the plumbing to the slave cylinder is required, as it is not used in its original position.

Subaru used many clutch kits for 200bhp to 180 bhp applications with these clutch arrangements. The most common ones used by customers are the 225mm clutch kit which suits up to 240 bhp, and the 230mm kit which suits up to 260 bhp. The 240 bhp 225mm clutch kit is very well proven in EG33 and MY00-MY03 EZ30 6 cylinder manual VW applications for normal use, when used with a suitable flat faced 254mm PDC single mass flywheel (Subaru never made manual versions of these engines).

The ‘pull to release’ clutches and their corresponding flywheel and these bell housing kits also suit some applications in VW conversions which did not originally use them, with examples being the MY00-MY03 EZ30 (no manual model was made), or normally aspirated EJ series engines in non normal use applications where a stronger clutch is required. Note there has seemed to be a belief at times, particularly in the VW Syncro world, that stronger (i.e. a higher torque capacity) = better in terms of clutches, resulting in customers fitting clutches with a far higher torque capacity than they need. In almost all cases this is a mistake, giving an excessively heavy clutch pedal with no benefit.

These kits include a new clutch release shaft, as the VW clutch release shaft cannot be used.

Flywheel:	From:	To:	Induction:	Subaru Models:	Engines
single mass, flat faced, 254mm clutch PCD	MY90	MY01	Turbo	all	EJ20, EJ25
single mass, flat faced, 254mm clutch PCD	MY02	MY04	Turbo	all 5 speed and / or up to about 250bhp	EJ20, EJ25

The release bearing and diaphragm spring centre that this bell housing kit works with are as below. It is not compatible with any other release bearing types (clutch parts not included):

If you’re interested in this kit, you may also be interested in the following associated parts:

800-00024 Clutch release shaft fitting kit
100-00073 Release shaft arm (hydraulic clutch)
800-00046 Bell Housing to engine bolt set – Phase I (2 bolts)
800-00062 Bell Housing to engine bolt set – Phase II (6 bolts)
040-00032 Lower engine to bell housing stud (per pair)
040-00043 Replacement input shaft oil seal
100-00042 Clutch kit, ‘pull to release’ 225mm, VW disc (good for up to around 240 bhp in normal use applications)
800-00063 Clutch kit, ‘pull to release’ 230mm, VW disc (good for up to around 280 bhp in normal use applications)
800-00042 Flywheel bolt set
100-00040 Flywheel cover

VW Bell Housing Kits for Subaru ‘push to release’ Clutch, Single Mass Flywheel, Turbo Turbo EJ Series or 6 Cylinder Normally Aspirated Engines (part number 800-00058):

Subaru introduced a new clutch arrangement for the lower powered (up to about 250 bhp) turbo models in MY05. For the first time in the turbo EJ series Subaru era, it is a ‘push to release’ clutch. However, it and it’s clutch release mechanism (and therefore bell housing kit) do not interchange with the similar normally aspirated ‘push to release’ clutch arrangement. This bell housing kit is specifically for them.

This kit also has the advantage of being able to have its clutch hydraulically or cable actuated, so will be of use if you’re using a lower powered turbo engine in an application which does not suit (or which you don’t want to convert to) a hydraulic clutch. They are not as well proven in applications such as the EZ30 or EG33 in manual VW applications as the 240 bhp 225mm ‘pull to release’ clutch is at present, but could be ideal for some niche VW applications.

These kits include a new clutch release shaft, as the VW clutch release shaft cannot be used.

The release bearing and diaphragm spring centre that this bell housing kit works with are as below. It is not compatible with any other release bearing or clutch types (clutch parts not included). Note the distinctive crank in the tips of the diaphragm spring and different release bearing:

If you’re interested in this kit, you may also be interested in the following associated parts:

How to Identify the Short and Long VW Input Shafts:

The Advantages of our Bell Housings:

No overloaded VW starter motors – an inherent and largely unavoidable problem when using ‘adaptor plate and flywheel’ kits to join Subaru engines to original VW bell housings. Note, adaptor plate and flywheel kits are your only option if you are using a type 1 gearbox, as they do not have removable bell housings.
No overloaded VW clutches or requirement to use ‘aftermarket only’ uprated VW clutches due to there being no space in VW bell housings to fit more suitably sized clutches.
No concentric clutch slave cylinders. A truly awful invention from a servicing point of view (they usually require replacement when changing the clutch, and cannot be serviced in any way without splitting the engine and gearbox), concentric slave cylinders only advantages are in assembly time and manufacturing cost. A conventional VW type clutch actuation via a clutch release shaft is very preferable, and also enables hydraulic or cable actuation and using the original VW actuation parts for all ‘push to release’ clutch applications (the ‘pull to release applications require hydraulic actuation, but still use the standard VW slave cylinder).
No need for awfully engineered ‘extensions’ to the gearbox input shaft required – the shaft remains installed exactly as VW intended, with no spacers between the two shaft sections.
Cast from and heat treated to the best specification for the application. LM25 TF (356 T6) – the same spec aluminium as used in almost all cast aluminium motorsport cylinder heads, blocks and gearbox casings.
Three recesses cast in to make separating the engine and bell housing far easier than it is in a Subaru (it’s very difficult, as Subaru seemingly didn’t think about how to separate them while designing).
Almost certainly the most details instructions you’ll ever see for a similar product – every detail explained, with photos of all major steps

Bell Housing FAQ:

121mm. That’s 4mm shorter than the standard VW bell housing, or around 16mm shorter then the typical Subaru adaptor plate and flywheel kit fitted to a standard VW bell housing.

In most cases, yes, you can change to the different clutch type by buying the relevant conversion kit to alter the clutch release mechanism with your existing bell housing. There are some combinations were this will not be possible – it depends which bell housing version you have. The design has changed many times over the years. Get in touch if you want more info on this – we’ll need details of the purchase date of your bell houisng kit or good photos of from the inside and out.

In most cases yes. The difference is in VW parts, not in parts from the bell housing kit. The main exception if if the bell housing kit is for a ‘pull to release’ Subaru clutch. They have to be hydraulically actuated, so you can’t convert one to cable operation. However, for relatively low powered turbo applications (up to around 240 bhp), if you don’t mind also changing the flywheel and clutch, you could use the turbo ‘push to release’ clutch from an MY05 onwards WRX or other similarly low powered MY05 onwards model, and your existing bell housing kit can probably be converted to work with it. Get in touch if you want more info on this.

All the parts which are not already in the VW or Subaru to join the specific spec of engine and gearbox together. This assumes the Subaru engine is from a manual donor car, so you already have the manual flywheel, starter, clutch fasteners, etc, as there is a manual and an auto version of most Subaru engines. If the engine is from an auto, or it you don’t have those parts (for example if the engine has previously been used in a VW with an adaptor plate and flywheel kit), you’ll need to convert the engine to manual spec. We stock most of the parts needed to convert the most common engines to manual spec.
None of our bell housing kits include any clutch parts.

Two possibilities, assuming the starter is from the same donor Subaru as your engine:

1. Your starter is from an automatic Subaru. The bell housings are exclusively designed to work with manual Subaru starter motors because the auto starters are not suitable, and don’t interchange with the manual models. A manual Subaru starter has a spigot diameter of 65mm where it locates in the bell housing – with an auto starter it is 82mm.

2. You have one of the MY90 – MY97 Denso starters which have the (smaller) solenoid inline with the pinion, and the motor offset. These only fitted early Subaru gearboxes, which were not designed for the later, larger clutches. When Subaru later redesigned the gearboxes for larger clutch options, this meant using space previously occupied by the starter motor flange, and the same applies to our bell housings. For many years now we have only made the later type, with room for the large clutches. However, these early manual starters can easily be modified to fit. You just need to file a chamfer on or saw off the edge off the starter housing:

In most cases any, all manual Subaru starters from EJ, and EZ series engines interchange, including turbo and normally aspirated. They are all similar wattages (including for the six cylinders). The main exceptions would be:
– if you’re conversing a late bay / T2b, avoid the MY90 – MY97 Denso starters which had the solenoid in line with the pinion, and the (larger) motor offset
– avoid the starters from the (ultra rare) manual twin turbo models (part number 23300 AA352) unless you have a twin turbo engine (definitely not recomemnded). They have the solenoid positioned above the motor to make room for the 2nd turbo. They’ll fit many VW applications, especially 2wd T25 / T3 /Vanagons), but not all others.

Not sure that anybody has ever specifically wanted to use a concentric slave cylinder, as they generally seem to be disliked. They definitely are by us due to previous bad experience with them in an OEM application in a previous job long before getting involved with Subaru engine conversions, we still (reluctantly) investigated developing a bell housing version with one back in 2003 – while designing the original version of our bell housing kits, and before a competitor used one in their product. However, here is why we chose not use them.
There were not very may concentric slave cylinders to choose from back then, and we investigated ones from various common European and US spec models, and came to the conclusion none of them were suitable for the Subaru to VW engine conversion bell housing application, so abandoned the idea of offering a concentric slave bell housing kit.
We briefly investigated this again in around 2006 or 2007 when a competitor launched a bell housing kit with a concentric slave cylinder. This was particularly interesting, because it looked like the concentric cylinder they were using was one which we had previously ruled as not suitable, for more then one reason. Maybe there was another version of it which was suitable, but no, they were using the VW slave cylinder we’d ruled out as unsuitable.

We get asked this occasionally – pretty much always by folk who haven’t looked at a Subaru engine and / or gearbox, and don’t realise that the slot is half in the bell housing, and half in the engine. Therefore the slot cannot be closed off by the bell housing. Our bell housings are designed so the flywheel cover from any Subaru model will fit. There are many variations of the Subaru flywheel cover. All are steel pressings, and are not designed to fully seal around the flywheel. All have a hole to let debris / clutch dust out, and this varies from 7mm diameter to a very large slot. Some from auto applications are two piece, with a large removable section in the middle. Why is not clear – it is not for access to the drive plate bolts when the engine is in situ in a Subaru, as it is not accessible. Maybe it is for access to them when assembling the engine and gearbox outside the car in the factory, however, this doesn’t really make sense either, as it would be just as easy to remove the whole cover (only 2 screws)

Those asking this question have probably seen a competitor’s bell housing, which when viewed on it’s own (i.e. not with an engine block) looks like it does not leave the flywheel exposed. However it does. It only covers half of the slot, leaving the engine block half of the slot open. It is impossible to completely cover the engine half of the slot with the bell housing, as that would make assembly impossible. With half of the slot covered by a different design of bell housing, the only way to cover the other half of the slot would be to use a part specially made for that job. With the way the flywheel protrudes from a slot which is half in the engine, half in the gearbox replicating the design of every Subaru gearbox, as with our design, the standard Subaru flywheel cover, used on every Subaru engine can be used.

Subaru flywheel covers often get damaged when removing the engine, especially on naturally aspirated models. The always come out with the engines, so don’t get left behind in the donor car. However, if whoever removed the engine assumes that it will sit the right way up when released from their engine crane, they may be about to find out that many of them don’t. Many tend to tip over onto the flywheel face, and when they do, this wraps the thin cover around the flywheel, badly bending it. They can be particularly difficult to straighten out well enough to fit correctly once this has happened, resulting in rubbing on the flywheel ring gear which makes a horrible noise (until the ring gear teeth wear the offending bit of cover away).
If you’re replacing a Subaru flywheel cover, any of them will do, but some have such a large slot in them that they barely do anything. Others have a large slot which faces backwards in the Subaru, but forwards in a VW so are best avoided.
The cover with the smallest hole is the ones from the EE20 engined diesels. They just have one 7mm diameter hole.

Weld up the hole in the flywheel cover if it is a large slot, or bridge it with Sikaflex if it is just a 7mm hole by taping over the hole from the inside, and applying the Sikaflex to the outside and leaving until it has cured. Don’t use silicone sealant instead of Sikaflex or an equivalent polyurethane sealant. It is unlikely to remain sealed, especially if it is general purpose household silicone.
Drill a 5mm hole in the two corners of the cover with no standard screw holes.
With the engine and bell housing bolted together, fit the cover to the engine with the two M6 screws.
Drill 5mm through the new cover holes and through the bell housing casting.
Remove the cover and drill the two new holes in it out to 6mm.
Tap the two 5mm holes in the bell housing M6 x 1.0.
Remove all of the foam seal and it’s adhesive from the cover.
Make sure you allow for the bell housing to be vented at the top (it mustn’t be totally sealed). If you want it to be vented to a remote location via a pipe, like the VW bell housing, as well as drilling and tapping for a pipe fitting, you’ll also want to Sikaflex the rubber cover for the Subaru auto drive plate bolt access hole into place.
Very thoroughly clean the cover, and also the engine and bell housing where all edges of the cover will be with something which remives grease but not paint, such as isopropyl alcohol.
Put a bead of Sikaflex along the block / sump join behind the flywheel, and atound the other 3 edges of the cover. It’ll need to be a thick bead where the foam seal originally was.
Fit the cover using the two M6 screws into the block.
Fit two additional M6 screws into the new holes, but don’t tighten them all the way down. Just enough to hold the gap between the cover and bell housing at a constant width and make sure the Sikaflex bead fills the gap. The Sikaflex will bond them in place once it has cured, so they don’t need to be tightened.

All Subaru starters are gear drive. Those which look like a traditional direct drive starter (i.e. with the motor inline with the pinion and the solenoid offset) have a planetary reduction drive between the motor and the pinion. The starters used in all of the MY90 – MY97 applications are the Denso type where the solenoid is inline with the pinion, and the larger motor is offset. They have a spur gear reduction drive to the pinion.

All Subaru clutch release bearings are self aligning. ‘Out of the box’ they usually look out of alignment.

The types shown below. At least two other Subaru release bearing types (not shown) have been used since the EJ series engines were introduced, but they either don’t fit, or do, but give a combination which is not compatible with any Subaru clutches when used in VW applications:

Subaru release bearing types which our bell housings use – there are other types too, but they’re not compatible

Note the two release bearings to the right in the picture above are functionally identical, so interchangeable. The upper one is the original design, and was superseded many years ago in all Subaru, Exedy (the clutch kit OEM) and NTN (the OEM bearing manufacturer) products because the small hooks can snap off. The lower one is the design which superseded it. High quality aftermarket clutch kits (typically made by the biggest, more respectable clutch manufacturers) tend to use the genuine NTN release bearings, so always the new type. However many cheap copies of the clutch kits have copied the original, not so good design.

All of our bell housing kits do used Subaru release bearings. But in some kits the Subaru release bearing is joined to a standard VW clutch release shaft with an adaptor. This adaptor is held on to the shaft using the clips from a VW bearing. They’re not available separately – only attached to a bearing. You may be able to re-use the clips from the VW bearing that you have removed if they are not too worn.
Ideally yu need the clips from the non dissassembleable LUK type VW release bearing. If you have the Sachs type VW bearing which can be disassembled, the bearing is held into the housing by the clips, which are longer. They’re too long for the release bearing adaptor from the bell housing kit, but can be cut down as detailed in the bell housing kit instructions.

The standard T25 / T3 /Vanagon slave cylinder, 251 721 263 or 251 721 263 A. They can be either the FAG or the ATE type (VW dual sourced the cylinders under the same part number), but don’t mix parts between the two (they’re interchangeable as a completer cylinder, but their parts are not interchangeable).

The top cylinder below is a (genuine) FAG type cylinder (the FAG product range was taken over by Valeo, who market the products as FTE, but apart from the logo on the casting changing, the FTE cylinders are the original FAG design), and has a black plastic socket on the end of the pushrod for the ball on the clutch shaft arm. The bottom cylinder below is a copy of the ATE design, and has a metal socked at the end of the pushrod, with a plastic cup inside. Both types have been copied by aftermarket brands, the ATE type far more so:

Both types of VW T25 / T3 / Vanagon clutch slave cylinder – they’re interchangeable as complete assemblies, but their parts don’t interchange

Firstly, if your kit came with shims, you need them, so don’t chose not to fit them unless you want hassle later. We’ve had various customers intentionally not fit them, only to find out, sometimes in a rather expensive way, that they’re not there for no reason.

If you’re interested the details of why in why the shims are needed in some kits, read on. The finer details of how clutches work are not widely understood, and this includes by some who believe with exceptional confidence that they know all about it. We have come across more than one garage owner or mechanic who after getting in touch looking for help because they have a problem with their clutch installation, quickly try to turn the discussion into an argument when told they have got something wrong such as choosing not to install the shims from their bell housing kit. One replied with with something lines of “don’t tell me how a clutch works – I’ve installed thousands of them”, even though they’d already proven that their supposed knowledge was very incorrect. A contact who is a clutch specialist at an OEM clutch installations agrees here, saying “Clutches are largely misunderstood”.

We spent well over half a day writing a very detailed explanation and creating diagrams showing exactly why the shims are needed and where the confusion about their function comes from to go here. However, after reading it, we removed it before publication on realising it was unintentionally also a detailed explanation of one of the two design errors in a competitors product, and wrote the following simplified version instead. We’ll continue to watch to see whether they ever work out what they got wrong, as we’ve been doing for well over 10 years now……

There is a semi-common misconception that putting shims between the flywheel and clutch pressure plate must reduce the clutches’ torque capacity, because it must reduce the clamping load (the force which which the clutch disc is compressed between the pressure plate and flywheel, which is proportional to the clutches’ torque capacity). If you want to understand this and where it comes from, it is worth first discussing old fashioned coil spring clutches first, as they are easier to understand, and also work how people who expect fitting shims to reduce torque capacity assume all clutches work:

A Coil Spring Clutch Pressure Plate:

*Old fashioned 1960’s VW coil spring clutch pressure plate*

A standard coil spring clutch has a linear relationship between the pressure plate displacement and clamping force.
Using a thicker disc than a coil spring clutch is designed for will increase the clamp load. However, it will also force the release mechanism to work outside of its intended movement range, and this could cause problems with running out of lever travel or spring fatigue.
The linear relationship means that as a clutch disc wears thinner during it’s life, the torque capacity of the clutch decreases. This is a major disadvantage of coli spring clutches, and the main reason why they were superseded by diaphragm spring clutches (from the mid 1960’s for VW).
Fitting shims between the flywheel and coil spring clutch pressure plate with a disc of the intended thickness has the opposite effect of using a disc which is thicker than intended – i.e. it reduces the clamp force and moves the working range of the coil spring levers in the opposite direction. This is the cause of the confusion……. but it is not relevant to diaphragm spring clutches.

Diaphragm spring clutch pressure plates superseded coil spring pressure plates in the 1960’s and 1970’s because they solve the problem of the torque capacity decreasing as the clutch disc wears. They’re almost certainly cheaper to manufacture too, as there are far less parts in them. They have a very non linear relationship between the pressure plate displacement and clamping force. This cab be taken advantage of to make the make the clamping force remain about constant or even increase as the clutch disc wears. But to achieve that you have to make sure you’re using the correct part of the clutches operating range. This is why the shims can be required when using some non-standard combinations of clutch parts.

If the shims do not fit your application, don’t try to modify them – this is a sign that you do not have the correct clutch parts for your bell housing kit. The shims fit their intended applications without modification. We have seen a number of customers try to modify the shims to fit applications which they are clearly not intended for, without realising that they have unsuitable clutch or flywheel parts, and without thinking to ask what the problem is. This never works – the solution is to use the correct clutch or flywheel parts.
Often this happens because a customer has an engine with a Valeo Subaru dual mass flywheel, but they don’t realise it is dual mass. The dual mass clutches do not interchange with the single mass equivalents.

We are not experts on how clutches work – we do not have access to the level of detail that clutch OEM’s have. But we are confident that we put more effort than most involved in aftermarket clutch installation design do into understanding them. That’s just an engineer’s attention to detail. There is always room to learn more, and this knowledge never comes from the opinions of those who believe having installed thousands of clutches makes them an expert, or from anonymous internet ‘experts’. If these were the sources of real knowledge, students would be taught using these as the sources of correct information. But of course, they’re not – they’re taught from text books and technical information from reputable sources such as technical papers by the biggest specialist businesses in the subject.
This is where we source our clutch knowledge from – mostly technical documentation from clutch OEM’s and by experimentation. If we don’t understand something, we are fortunate enough to be able to check our understanding with the OEM clutch installation engineer at one of the biggest OEM’s (thanks Mike). Anyway, rant over, just consider that your bell housing kit or adaptor plate kit supplier or installer may well not actually understand clutches as well as they think they do. Errors in some of their products are obvious, such as using incompatible parts, yet they seem oblivious. Good news for us as we sell our bell housing kits to their customers once they get fed up with the resulting clutch problems, but bad news for Subaru to VW engine conversions in general.
How do you experiment with clutches and what do you learn from that? We plot the clamping for curve for all clutches of interest that we can get our hands on. This is extremely useful as it gives a very good idea of maximum torque capacity – both absolute and relative to other clutches. This started with wanting to benchmark every normally aspirated single mass flywheel EJ25 clutch we could get back in around 2009, when our previous favourite clutch supplier changed they way they sell clutches in the UK. That helped us choose the best one for our application, based on a few parameters, and proved to be well worth doing, as the ‘winner’ proved to be far superior to the clutches we previously stocked. Trying all of them in vehicles wasn’t practical, and wouldn’t provide very much information anyway, but bench testing them first, then trying only the likely ‘winners’ was practical, and meant much more data could be collected. Other experimental work which gives info which is not available outside of the OEM’s involves measuring the release characteristics of the relevant clutch types to determine how to use them in our bell housings, and calculating their design torque capacity safety factors. The latter is also a very useful / amusing way to see just how optimistic / uninformed those selling adaptor plate kits with 215mm VW clutches into moderate to high powered Subaru applications are.
This benchmarking created the first 9 clamping force curves (data which is not usually available outside of the OEM’s), in our now much bigger collection, some of which is shown below:

Price: from £468.33 GBP + VAT (£562)

VW Bell Housing Kits for Subaru ‘push to release’ Clutch, Single Mass Flywheel, Normally Aspirated EJ or FA Series Engines (part numbers 800-00001 and 800-00021):

VW Bell Housing Kits for Subaru ‘pull to release’ Clutch, Single Mass Flywheel, Turbo EJ Series or 6 Cylinder Normally Aspirated Engines (part numbers 800-00003 and 800-00052):

VW Bell Housing Kits for Subaru ‘push to release’ Clutch, Single Mass Flywheel, Turbo Turbo EJ Series or 6 Cylinder Normally Aspirated Engines (part number 800-00058):

How to Identify the Short and Long VW Input Shafts:

The Advantages of our Bell Housings:

Bell Housing FAQ:

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