BEC gear change clunk!!! (probably a silly question)

[Billy Bob]

Ok so I am sure that everyone has or is in the process of getting the cars out or their winter cotton wool, I have taken my Blackbird engine Westfield out for its first run this afternoon, it was great (after stalling it at least 6 times before the end of the road and I live on the end of the road!!!)
Anyway to my question, I am getting a large clunk during 1st -2nd and 2nd to 3rd gears, this is not a small normal clunk its quite a bang, like there is a lot of wind up in the system (except that the clutch is pressed and it does not seem to need bleeding!!)
The car has the Westfield 'R' box and this is a little difficult to select, is it possible that there could be some odd interaction here??

Any thoughts welcome or any know issue to help narrow it down!!! Would hate to think I cant make the most of this weekend :-)

[Quarrycars]

A couple of questions: Is the clunk as you release the clutch or as you make the shift with the clutch depressed? Do you hear a clunk when you get on and off the gas and is it the same in all gears? Don't know anything about bike engined cars (I'm assuming the Blackbird is the bike not the SR71! ), is the 'R' box for the  reverse?
Don't know how much of the drivetrain you can see from above but if you put the drive in first gear and roll the car back and forward you may be able to see, feel or hear if there is exess play somewhere.

[Billy Bob]

The Clunk is as I engage the gear with the clutch pressed, ('R' is the reverse) I did try to get it in 1st and roll it back and forth but you cant get it in gear unless it is running, I guess I could put it in gear and switch it off but am not sure if this would work!! I did find that if I start it up and idle it for 30 seconds or so then clutch in and into 1st gear the 'bang' is there. With my mates head under the back of the car at the time he said it does look like there is drive to the prop and the bang is from the diff/ powertrain. All seems odd to me as the clutch in pressed!! Any thoughts welcome!! :-)

['The Gaffer']

I know from experience that all bike engined cars clunk from one degree to another. Mine clunks like a good 'un even after a full transmission rebuild. Its caused by the backlash in the gearbox. You will probably find that if you jack the car up with it in gear (engine turned off) and you turn the prop you will have maybe a good quarter turn of free play, its that free play that makes the noise.

It could however be some wear on the prop, your reverse box worn (not uncommon) or maybe you are just more sensitive to the noise, perhaps not wearing a helmet when maybe you did before making things sound louder?.

Below is a video of the slap in my gearbox, when the prop and diff were connected the noise travelled down making a horrible noise. Now much better with a tube in tube prop. Hope you dont find a problem.

[Quarrycars]

The fact that the prop tries to turn when you engage a gear seems to indicate that the clutch is dragging (not disengaging fully). It doesn't look like there is any adjustment at the engine end, is there any adjustment at the master cyl?
Try pumping the pedal a few times before engaging the gear, if it is smoother there may be a bleed problem. I'm guessing it is a 'wet' clutch so the oil may be critical. As Phil says it is normal for there to be a lot of backlash because you are engaging gear dogs instead of synchronizers, that is why is difficult to engage gears when the engine is off, you may have to roll the car a bit to get them to click in. Of course I'm just speculating here, the guys with similar cars will be a better source of info. One other thought, bikes usually have a cushion in the driveline to minimize shocks, the car may just feel harsher.

['The Gaffer']

The fact that the prop tries to turn when you engage a gear seems to indicate that the clutch is dragging (not disengaging fully). It doesn't look like there is any adjustment at the engine end, is there any adjustment at the master cyl?

I get a clunk while engaging first with the clutch pressed in.

Try pumping the pedal a few times before engaging the gear, if it is smoother there may be a bleed problem. I'm guessing it is a 'wet' clutch so the oil may be critical. As Phil says it is normal for there to be a lot of backlash because you are engaging gear dogs instead of synchronizers, that is why is difficult to engage gears when the engine is off, you may have to roll the car a bit to get them to click in.

Yes maybe a clutch problem, but wouldent the engine stall if the clutch was dragging? How far up the pedal does the clutch bite? As long as its not right at the bottom you should be ok. Bear in mind though that clutches in BEC's have a hard time compared to being in a bike and can wear a lot faster. Do you know if your clutch has been uprated? Barnet springs are a min requirement.

One other thought, bikes usually have a cushion in the driveline to minimize shocks, the car may just feel harsher.

I have just had a tube in tube prop made. It has a rubber tube inside seperating the two prop surfaces. This really quietend things down. A normal prop acts like a huge sound box amplifying any clunks from the gearbox.

Other obvious things to check are oil levels and oil quality. As the gearbox and clutch uses the same oil as the engine it is very important that level is correct and you are using a top grade oil.

Check the level in your reverse box too. If you have grease nipples on your prop, grease it up. Just for piece of mind check the diff for correct oil level too.

If its any consolation, I had some of the best transmission guys under my car listening to the clunks and bangs only to find out later that the noises were perfectly normal. BEC's are so different to normal engined cars. I even swopped the diff twice convinced there was something wrong with the original

All the above may be irrelevant though not hearing the noise you describe, can you post up a youtube video of the noise?

[Billy Bob]

Thanks for  all the feed back, I do have, as you put it, slap in the gearbox but was not too worried about this, I will try to get a video tomorrow one from engine side and one from under the diff, the biting point is very high and there does not seem to be any drag at all when in gear and on the clutch. However when I engage a gear, even stationary there is a bang and the diff does move, I cant work out where this drive is coming from!?!?! quite confused I have to say. (though I am new to BEC's!! I'm more used to 5.0 v8's !!)
but it is quite quick!! 

['The Gaffer']

If you can imagine putting the car in gear when the backlash in the gearbox is at its greatest, i.e. ready to turn to take up the slack, then the prop will turn until that backlash is taken up often making a loud clunk. Other times if you put it into gear and the slack has already been taken up i.e. prop wont turn then it is much quieter.

If you watch the chain on a motorcycle when it's put into first, normally it will tighten with a clunk. Nowhere near as loud as a prop though because it's got more mass.

Here is vid of backlash slap in my gearbox - quite normal. http://share.ovi.com/media/GandToniq.Toniqs/GandToniq.10009

Here is vid of that backlash taking up and releasing again because wheels were off the ground - Quite a racket but again quite normal for a BEC. Its simply an amplification of the above slap. http://share.ovi.com/media/GandToniq.Toniqs/GandToniq.10010

Look forward to seeing your vids.

[Quarrycars]

More thoughts on driveline clunk: I imagine it is normal for there to be some drag on a multiplate wet clutch, especially when cold, is it better when it gets warm? Idle speed may have some effect also. As Phil says when you engage the gear on a bike you feel a slight thunk as the chain slack takes up, but the bike doesn't have to take up the backlash in another gearbox and a diff!
A tip from a biker friend who says that Hondas are particularly bad for clutch drag is to blip the throttle a couple of times with the clutch depressed to free up the plates before engaging the gear.
You mentioned a clunk while driving, this may be just getting used to the clutch/throttle coordination, a typical complaint is that fast full throttle shifts are fine but more leisurely driving results in clunks because the vehicle has time to overrun the drive line slightly between gears.

['The Gaffer']

You mentioned a clunk while driving, this may be just getting used to the clutch/throttle coordination, a typical complaint is that fast full throttle shifts are fine but more leisurely driving results in clunks because the vehicle has time to overrun the drive line slightly between gears.

I second that, and temp dosent seem to make much difference, if anything mine is clunkier when its hot. I imagine because things are more free to turn.

[Billy Bob]

Hey thanks Guy's I am still getting used to everything so I took it out again and tried different gear changes with the result being 'the faster the better' so next move is clutchless up shift to see if as I thought it was just driver error!!!! Maybe taking too long with the clutch was allowing the wind up/ backlash to reach just the wrong point before changing gear!!!! Thank you for all your effort with your responces as it has given me a lot to think about!! 
I have to admit that I still dont undertand the whole bike engine/ gearbox as this is quite differnent (it would seem) to a normal car i.e I cant work out how any drive gets transfured to the drive shaft if the clutch is in! (or am I going mad!!) but it is a learning curve and I am loving it!!! 
Again thaks for your help and advice you have to love this forum (sorry I am so far away 
Ha Ha hope you are all enjoying the weather though, time to blow the cob webs out of the engine bay!!!

['The Gaffer']

Maybe you have nothing to worry about then. We might see you on the Stoneleigh run and we can compare notes?

I think the difference between a bike and car clutch is that the bike clutch has more plates in a 'basket' that is immersed in oil as opposed to a car clutch that has only two surfaces that make dry contact.

Logic dictates that the wet bike clutch is more likely to have a little drag than a dry car clutch.

Good luck with the gear changes, things are just different with a BEC, its just a question of getting used to the clunks etc.
You will find the faster you go, the quieter the transmission is

[Billy Bob]

Ye I will be trying the different changes just as soon as the British summer weather starsts to play ball, (its not at the moment!!) 
I will also try to get to the show, its closer to me than work so I really should make the effort to get there for a few hours!! :-) I'll keep a look out for the stand and pop in
Very much looking forward to the summer and I hope to not be posting too many stupid questions on here as the weeks go on!!! ...................though I do have a nother which may well appear at lunch 

[Billy Bob]

Well I have decided to post this as an addition to this post as it is related.
The summer weather is here with a vengeance and so I have been dually out and about in my car :-) however as I was leaving work on Monday I made it a few yards and pop, bang, clank............. loss of drive and a some what upsetting feeling of a prop flapping about by my leg.
1. lucky I was doing about 5mph in the car park at the time.
2. Very Lucky a friend of mine was able to help me push it under cover and give me a lift home
3. Very very lucky another friend of mine drove quite a distance to bring a trailer, pick up the car and bring it back to my house.
4. Very Very Very lucky I was not 5 min down the road doing the......... err..... national speed limit when it happened!!!!

I have had a quick look underneath and it looks like the bearing has failed on the R box as the front prop section is still attached to the interface with the R box but unfortunately the interface (flange!?) and spine section is not connected to the R box :-(

Until I can get the R box out over the weekend I don't know if it has chewed its self up or not, I am hoping not as it was such slow speed but it could be expensive if it has!!!

Do Westfield do a rebuild/ rework kit I am sure I have seen somewhere that they do, I have e-mailed them to see what they say!

Has anyone else had this happen to them, I have seen people saying that the R box's can be a bit of a problem but nothing like this! I guess that the knocking I was experiencing was indeed a little more than normal!!! ha ha oh well at least me and the car are in one piece  (except for the R box of course!! )

Hope you are all making the most of the weather 

[Daley Down Under]

I had similar challenges with my reverse box (although not quite as catastrophic).  Rather than refurbish, I took mine out, sold it and got Bailey Morris to make me up a new front and rear prop (with centre bearing that bolted straight on to the Reverse Box mountings).  Total cost for props and bearing = £350.  If you can do without reverse, I'd recommend this route.

Adrian

[Billy Bob]

Ye I like your thnking and a center bearing would be a good idea with the angle involved from the out put to the diff, however this would have to be a last chance option as I would quite like to retain the R box (in one form or another) but if this is not feasable I may PM you if that is ok to get some details 
thanks for the feedback.

[Daley Down Under]

Bailey Morris said you couldn't use a single prop over that distance at that speed even if you want to.  Centre bearing scheme worked really well - never had a single problem over 7000 miles and lots of track days.  Good luck with repairs

['The Gaffer']

however as I was leaving work on Monday I made it a few yards and pop, bang, clank............. loss of drive and a some what upsetting feeling of a prop flapping about by my leg.

Ooops, really sorry to hear your news. Reverse boxes do have a reputation for being the weakest link

Get rid of it and never look back, in the last 1000 miles I guess I would have liked reverse on 2 occaisions and that was that.

Hope you get things sorted quickly to enjoy the sunshine.

[Billy Bob]

Well I now hav ethe refurbished R box back in the car, (and a £300 lighter wallet!!) basically the castle nut on the front flange of the box had worked it way loose (on this model of box the thread is not against the direction of rotation, add to this the poor effort at peening the nut into the groove on the shaft!!) so the flange fell off!!!!

Lucky this happened at 2mph!! ANyway all on its way back together when I noticed that the front prop has lost a grease nipple, I have found a place on the internet that has some 1/4" long length grease nipples in BSF and UNF but as I dont know what donor parts are used for the Props I am not sure which to go for!! Does anyone have an idea?

[Richard]

No idea on that car, can only suggest you try a few small bolts if you do not have a means to measure it or size the thread (tapping set would help here).

[Quarrycars]

Billy Bob
I think the threads of grease nipples for car prop shafts all the same, I have boxes of new grease nipples I'll check the threads, I can send you a few of each if you like.
Cheerz, JT

[Quarrycars]

These are the grease nipples I have, the 3 on the left are 1/4" X 28 UNF, the one on the right is 1/8" BSP/NPT.  The angle one seems a bit odd, I measure it as 5/16" X 27, not a thread I recognise, may be 8 X 1.0 mm?

[Billy Bob]

Hey thanks for looking this helps a lot, The ¼ UNF long is the one I am after (I think) so I have now ordered 5 off e-bay for about £4 delivered!!    Thanks for confirming the size and thread type, this was the pit I was having difficulty with!
Thanks for your time and effort it is much appreciated, I'll let you know when it is all back together.

Next step getting the geometry done correctly!!! (it under steers more than my Focus, a lot more!!!)