Pilot Bearing Inlcuded in RJES Bellhousing Kit

[wwvanayakagon]

Hey there...

I have a Subaru Conversion that I had done with a RJES bellhousing kit. The engine mounts are from Small Car (Arghhh) and then the Vanagon is a 1986 syncro with the syncro 4 speed transmission, engine is a 3.3l out of a 92 svx.

Ok so long story short. After about 6-8k miles on the conversion the Pilot bearing basically fell apart which caused some input shaft movement and loosened up the input shaft seal.

Took it all apart and the pilot bearing was toast, the input shaft seal was not that bad but clutch pressure plate ect was soaked from the amount of fluid slinging around.

I had a new input shaft placed into the transmission, I went down and got a new 6002 pilot bearing and was ready to put it all back together again with a new clutch kit when I realized the amount of play in the pilot bearing seemed excessive.

The 6002 bearing has an interior diameter of about 14.91 mm and the problem is that input shafts greatly vary. I pulled about 10 different Input Shafts out of my mechanics supply and measured them all. They all were around 14.58 to 14.69 mm which allows for almost .2 MM of play which seems very very high and in some cases it could be up to .4 mm

Does anyone know what the acceptable amount of space is between the pilot bearing and inputshaft for this type of conversion. I know that I measured other pilot bearing variances on the subaru input shafts for 2.5l and the 3.0 l and they were no more than .1 mm in difference.

Any help would be great. I am ultimatly wondering if folks have used different pilot bearings to close that gap up and decrease the play?

Thanks
James

[ElusiveStranger]

ooooh, I wouldn't have a clue. I just bolted mine up - took it as gospel that it was ok.
I've done 18mths at 6,000 mile per year & don't apear to be having any problems
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The advice you receive on here is worth the paper it's written on.
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'78 Bay, 2 litre 091 box, EJ20 NA & the ashtray's on the 'right' side.
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[wwvanayakagon]

Well that does not help me out very much...

Volks Folks seem to think that it is acceptable to have up to 4 One Thousanths of play in the Pilot Bearing against the Shaft, however Subaru Guys that handle higher Horsepower & torque engines tend to say that anything over a thousanth is too much...

[ElusiveStranger]

*shrug* I just thought I'd let you (and others) know I've experienced no problems as yet.
_________________
The advice you receive on here is worth the paper it's written on.
Your experiences are worth shed loads to others, including the f'ups - live and learn.
Wouldn't YOU rather learn by someone else's mistakes? So would they.

'78 Bay, 2 litre 091 box, EJ20 NA & the ashtray's on the 'right' side.
I don't lean forward for hills any more
Bugger, missed out on "Live fast, die young"

[rjes]

Sorry about the delay replying. I've been having major e-mail problems the last four days, and have had time to do very little other than try to fix them.

Sorry to hear you are having problems. I am surprised that you didn't get in touch with me directly as soon as it happened. I'd have happily sent you a new pilot bearing and input shaft seal (just in case). I have all the design info for bearings and their shafts and housings.
The needle roller bearing which VW use to support the input shaft is an HK1512 open ended needle roller (in both T1, T4, and WBX applications), which is designed for use with a shaft of 15h5 (15 -0 +0.008mm), with a roundness tolerance of 25% of the maximum shaft dialeter tolerance (ref SKF bearing catalogue). This is likely to be far more critical in a needle roller application, as the shaft is the inner race. That's pretty close to 15mm.

Regarding actual diameters of VW shafts, I have two to measure. One has clearly been rusty at some point, and is very slightly pitted. The other is almost immaculate, with the origninal grinding marks visible all over. It could certainly not be described as worn, and only a slight polishing giving away where the bearing has been.
Starting with the once rusty one, it's diameter vaties from 14.91 to 14.93mm. The near immaculate one measures 14.88 - 14.89mm.
The nominal diameter is probably uspposed to be 14.90mm. Note this is less than specified in the SKF catalogue for the HK1512 bearing, and is consistant with the 0.1mm undersize you measured with the Subaru shafts. All of the above were measured with a micrometer.

Regarding the internal diameter of 6002 bearings, they are out of spec unless within 15 +0 -0.008mm. They should be nowhere near as small as the 14.91mm you quote. I have just measured about six, including two different makes (with digital veriner calipers, as I don't have an internal mike). All measure from 15.003 - 15.005. I have to admit that I don't understand why this seems to be a plus tolerance rather than the negative one quoted above. I could be that my digital verniers are slightly out of calibration, but I've never mentioned them being so on any other jobs. However, it shows that the tolerance is considerably tighter than the 14.91mm you mention.

A clearance of 0.1mm sounds ideal to me, and is near identical to the 4 thou (0.1016mm) quoted by 'VW folk'. This is also a perfect match with the apparent nominal shaft diamete I measured of 14.9mm.

I have never heard of this problem, or anything like it before. The closest I have seen is an aftermarket light weight flywheel in which the centre bore was too big. The bearing was loose in the bore, and had to be Loctited in. I didn't get a chance to measure the bore, but I put this down to the aftermarket flywheel being out of tolerance. It was very cheap.

Regarding usind different bearings to 'take up the play', you don't have the choice. Bearings are made to international standard sizes by all manufacturers, and the size ranges are (usually) based on integer nominal values. i.e you can't flick through a catalogue to find a bearing with a bore of, say, 14.68mm. The normal range of sizes for deep groove ball bearings such as the ones in question here is 10, 12(subaru), 15(VW), 17, 20mm..........etc. For the needle rollers as used by VW, the choice is the same, plus 13, 14, and 16mm.

I have to conclude that your shaft diameter and bearing bore measurements are not accurate, as they are so far from the actual (bearing) and apparent (shaft) nominals.
_________________
Regards,

Richard,

R J Engineered Solutions
Quality Subaru Powered VW Components
www.rjes.com

[doppelganger]

well i hardly understood a word of that other than the bit about my flywheel ive done about 20k with no probs at all
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[rjes]

Put more simply, there's no way the ID of a 6002 bearing can be 14.91mm. I also doubt that the shaft diameters quoted are accurate too, after measuring the shafts I have available. They are so far under the apparent nominal shaft size of 14.9mm that the shafts would have to be really badly worn to be that small.

Maybe whatever they were measures with was not calibrated / zeroed propery?

Personally I have not done as many miles on my conversion as some of my customers have. At least two have done over 18,000 miles with no such problems. There must be a reason why the bearing failed in this case, but I very much doubt it can be anything to do with the diameters quoted.
_________________
Regards,

Richard,

R J Engineered Solutions
Quality Subaru Powered VW Components
www.rjes.com

[rjes]

Having spoken to the guy who actually installed this conversion, there is more going on with this failure than has been mentioned in this thread, so I thought I'd add the details.

Shortly after the installation was completed, the (Syncro) gearbox suffered a nose cone casting failure due to a badly damaged, out of balance prop shaft. The oil all leaked out, and some debris may have got into the box. The repair consisted of replacing the nose cone and refilling with oil.

The pilot bearing is not the only bearing to have failed. The bearing at the engine end of the input gear shaft has failed too. This bearing effectively also supports the opposite end of the input shaft. the box has been stripped and inspected by AA Transaxle, who originally rebuilt it, and are apparently very good. The failure of the bearing at the engine end of the input gear shaft is suspected to be due to debris or lack of oil caused by the bose cone failure.

I've asked whether it is possible to get the pilot bearing and shaft(s) measured again, as there is no way a 6002 bearing is 14.91mm ID
_________________
Regards,

Richard,

R J Engineered Solutions
Quality Subaru Powered VW Components
www.rjes.com

[wwvanayakagon]

Richard,

You were correct on the initial measurements being off. The micrometer was not Zero'd

That being said we did a bit of re-measuring and there are differences in the shaft just not with as much variance as initially thought.

Since my original post, we did start hunting down other items and found some other reasons, that this could have happened. The initial post was just my attempt to start researching the areas that seemed off at the time.

Were back running again and with all new bearings I should know in another 8k if that was really the issue.

Thanks for the responses.

James

[rjes]

Hello James,
Thanks for the feedback. Glad the mike wasn't zeroed - I knew those dimensions couldn't be right!

If it's any consolation, I've just blown a Syncro box too. The ring gear on the rear diff has broken, possibly due to it picking up debris from a broken shift rod bush. The prices I'm hearing for all the repair options are scary!
_________________
Regards,

Richard,

R J Engineered Solutions
Quality Subaru Powered VW Components
www.rjes.com