MadaboutKitcars

As some of you know, I have been worring about my propshaft flange rubbing on the gearbox selector lever.

My little run at the weekend has confirmed that i do have a problem. Sure enough the flange rubs on the shoulder of the Tee piece when Reverse, First or fifth gear is selected.

I had a chat with Simon at Marlin today. He said he had some that had come close but not actually touched. He had not built a 2 litre version, so I wonder if my gearbox is different to the 2.5 litre? He suggested I spoke to Proptech who make the propshafts.
Spoke to a helpful guy at Proptech called Martin who said that he had not come across this problem before but, could 'turn it down' to a smaller diameter for about a tenner plus carraige!
Some photo's here....

http://www.flickr.com/photos/peters-bmwmarlin/
(I've borrowed one of Jason's photo's, thanks Jason)

So far I can think of four options but would appreciate any other ideas

Option1 - I've assembled something incorrectly? Any ideas?

Option2 - take the prop off and send it away to be machined but might need to drop my exhaust system to get the shaft out and my propshaft was a b****r to fit - arghh!

Option3 - drop the shaft, remove the tee piece and grind it down and refit. Same work as Option2 but next to zero cost.

Option4 - put washers or a spacer between the propshaft flange and the gearbox output flange to move the propshaft flange further away from the gearbox. I'll need slightly longer bolts which isn't a problem, but will it be safe? Will this cause vibration? Will it look a bit unprofessional to the SVA inspector?

Any other ideas or options? I need your help on this one!

If the prop is adjustable enough you could put a doughnut in. That would space it out and is fitted as standard to a lot of BM's:

Part 2 on here: http://www.realoem.com/bmw/showparts.do?model=AH52&mospid=47295&btnr=26_0062&hg=26&fg=10

Otherwise I would go with option 2. If there's not much that needs to be taken off the I would go with option 3. However option 2 is not that expensive so I would probably settle for that

I don't think you could have put it together wrong, might be worth checking the length of the bolts, I could see those causing a problem if they stuck out too far.

EDIT:

Here's a pic of mine, the flange is quite big too but I've not had any rubbing issues:

I can't imagine that the gearbox is any different to the 2.5, other than the ratios may be a bit different.

I presume that the flange of the special propshaft is much larger in diameter than the BMW one? I haven't got my propshaft yet and so I haven't been faced with this particuler problem.

I think I would do 2 and 3 (But then I am a belt, braces and string man). When you consider how fast the prop rotates you definitely dont want anything to have any chance of rubbing on it.

Robin

No probs mate.

Erk - that is tight. Have you measured the prop flange? Is it any bigger than anybody elses? What size is Patricks? (ooh err )

I don't have a prop yet, so I cant help out there - but I just wonder if it's another legendary Marlin laser cut part....

Pete - the output flange from the gearbox - is it round? It looks like it from the pics. I only ask as the output from mine is a like a three lobed triangular afair:



I wonder if this is slightly thicker than yours? That might have the effect of pushing the prop backwards, allowing the larger flange of the prop to clear the t-piece...

The flange on the gearbox is 3 lobed. The flange on the propshaft comes from some other vehicle and is re-drilled (and bushed?) to fit the beemer. - Hence the extra holes in it and why it seems to be excesively big (too big in Peter's case!)

I guess that the prop maker doesn't always use the same flange, or that the bit on the 'box it is rubbing on is slightly different to what others have used in the past.

Cheers

Robin

Yes, but from the pictures on Pete's flikr site, it looks as if the round prop flange is bolted to a round output flange of the same diameter - but having looke again, I see that it's where the rubbing of the T-piece has scraped the paint of the prop flange, making it look like two mating pieces.

There's no dimension change in the hight of the t-piece to the box output across getrag boxes is there? I know the 325 had a Getrag 260, but I seem to remember reading that the 320 had a Getrag 240?

Is the casing any different?

EDIT - forget that - the 240 was fitted to 4 cyl cars, not the 320, which of course is 6.

EDIT 2 - Is it a Getrag box? or is it a ZF? They fitted both to e30s - maybe there's a difference there. But as Robin points out, it's more than likely an oversized flange.

If its anything like the later models then there may be a difference.

ZF boxes on 328/M3's for example have a completely different throw to the smaller engines. If you put the M roadster stick on the shift it still hugely long. Where as a the Z3 1.9 gives a much short shift on lower down models.

But I think they are both Getrag boxes, the only different ones being the sport boxes that have closer ratios between 2, 3 and 4.

Thanks, Patrick, Robin and Jason for all your ideas.

Firstly, the doughnut doesn't fit because the new flange is flat, but your suggestion has got me think about the old flange on the original Propshaft from the beemer.

Thanks for the picture of your p-shaft. It is definately different to mine because mine has 6 surplus holes whereas yours only looks like it has only three? But the diameter looks similar?

Robin is right, the guy at Proptech said they use a ford flange and modify it. Looks like they picked up the wrong one when they made mine?

Jason, yes my output flange is just like your three legged flange but you may be right about thickness?

Gearbox type? My gearbox from the donor was knackered so this is an ebay buy. Acording to the guy I bought it from, it was from a 320i. Maybe the gear selector rod throw is longer on 320i's?

My current thinking is to put a 10mm spacer between the new flange and the gearbox output flange. As Patrick says, the doughnut is normally fitted and this has much longer bolts, so an extra 10 mm shouldn't be a problem. This will save all the phaffing about sending the p-shaft away, etc.
The spacer should move the over size flange clear of the gear selector rod and Tee piece.

This Kitcar industry seems to have no concept of quality control or customer satisfaction!? Using the wrong size flange just seems to be laziness because they can't be bothered to find one the right size? There is absolutely no good reason for the flange being this large.

I've taken another look at your photos Peter - Is there no way you could flip the prop end for end - so that the flange you have bolted to the diff is bolted to the gearbox? The flange on that end looks smaller.

Good idea, but the diff end has four bolt mounting so that won't work.

Just been looking again at Patrck's website for any clues. I had forgotten that he had also renewed the gear selector Tee piece. I wonder if the new ones are a smaller outside diameter. Mine still has the original that has a flat spring clip to keep the pin in place. Patrick has fitted a new type with the round spring like your new one.
But i'm also pretty sure the flange on his propshaft is different. Fundimentally, the flange is too large. I have written to Terry.

cheers

Peter

I think the problem with Marlin is that they like the development phase more than the production one. Speaking as an engineer myself (albeit not mechanical) I can understand that - nothing strokes the ego of an engineer more than making something new that works well...

The problem is sooner or later you have to make some money - which normally involves having happy customers - or you cease to exist.

I first built kit cars 25 odd years ago and its fascinating to see the kit car companies come and go. Marlin are actually one of the more stable ones, although its had at least two if not three owners. Even so, when I bought my kit a couple or three years ago I made sure I bought everything I needed to complete it in one go....

Robin

Except your propshaft! (sorry Robin, I couldn't resists that one)

Probably a wise move. The really annoying thing is that I considered getting my own built with a propshaft maker directly, but opted for the Marlin option so that I wouldn't have any issues! ha ha.

Peter

I also am considering getting my propshaft made elsewhere. Did you get as far as getting any recommendations for suppliers?

Cheers

Robin

Hi Robin, no I never got that far. Sorry can't help.

Peter

For my Marlin Cabrio/BMW M20 I had a prop made up to my own design. I got quotes from Recoprop in Luton (whom I'd heard good reports about) and Dave Mac Propshafts in Coventry. I went with Dave Mac in the end as they were half the price of Recoprop and did an absolutely superb job - I cant recommend them highly enough:

John McMahon (johnmac@davemacprops.co.uk)
1-3 Northey Road, Foleshill, Coventry, CV6 5NF, UK
Telephone: (024) 7668 3239
Fax: (024) 7658 1852

I remember John McMahon telling me that there were two common sizes of hookes joints used in automotive propshafts and he recommended the larger size (because of the relatively high torque & power of the BMW engine). However, knowing that the flange diameter could be a concern for clearance to the gear linkage, he machined the flange down for me to the same diameter as the 3 legged BMW output coupling. He also machined and fitted an insert into the hollow part of the hookes joint flange to allow a centralising hole for the 14mm spiggot that comes out of the BMW transmission. The following photos show the finished prop (there are more photos on my Flickr site http://www.flickr.com/photos/marlin_bmw_cabrio):


http://www.flickr.com/photos/marlin_bmw_cabrio/442093933/



http://www.flickr.com/photos/marlin_bmw_cabrio/448628636/

I also contemplated getting the propshaft from Marlin, but bearing in mind it took them over 9 months to deliver my bumpers and hood (yes that right - 9 months!!) I decided against it. It would appear that it takes less time to make a baby than it does for Marlin to make some bumpers...

Thanks Simon

That propshaft looks much better than the Marlin one - a "proper job" as they would say in the west country. I think that I will try your supplier.

Cheers

Robin

Simon - did you have to supply a donor bmw prop to be modified, or was the whole thing custome built?

How much was it, if you don't mind me asking.

Ta,

Jason

Jason,

I already had a standard Cabrio prop (that went with the Sierra gearbox and diff) and had originally thought that this could be modified. However, as well as needing the front to be modified it was also way too short, so in the end DaveMac just re-used the rear joint (Sierra diff end). I cut the end off the BMW donor propshaft (the prop side of the SGF coupling being the same as the transmission side) to allow DaveMac to machine up the hookes joint flange(although I dont think this was strictly necessary as he said that he had already made up quite a few kit car props to connect to BMW gearboxes).

I think the cost was about £170 inc VAT, spraying and balancing & took a few days to make.

Have you got your propshaft yet? I guess if you're in Northampton they are fairly local (being in Coventry).

Cheers

Simon

No, I haven't... And I don't have the original BMW prop, as I had 'dismantling issues' and had to cut in half with an angle grinder to get it out!

That's whay I was asking if you needed donor pieces to supply the prop maker.

I'm sure DaveMac wont have any problems making you one up from scratch even if you dont have any donor parts. John McMahon is a really nice chap and extremely knowledgeable about props - definitely worth you giving him a call or sending him an email.

Quick update on my propshaft issue......

Following some emails (:yelland a picture Terry at Marlin, Proptec have agreed it is wrong and their mistake. Apparently, they have had one other 320i builder with the same issue.
Now i've just got to get it off again (oh, er misses) which I fear means dropping my custom exhaust system

Interim update:
I managed to get the propshaft off without having to remove anything more than the exhaust to gearbox mounting bracket which was a great relief. Posted it off to Proptech and got it back today, nicely turned down to 11cm diameter. The guy at Proptech said this was the third one he had done (which was little surprising since Marlin had apparantly not heard of the issue?)
I will have to wait until next weekend to check how well it fits, but it looks like it should be fine now.
Anyone ordering a propshaft from Marlin for a e30 2 litre 320i should make sure they ask for the flange to be turned down to fit.
I'll post another update when its been re-fitted which will, of course, require a test drive to confirm it works!!

Nice one, any excuse for a test drive

Just had a quote from DaveMac £175 +vat which seems pretty good to me. Whats more if I chop of the back end of the old propshaft and send it to him they will reduce the price by the cost of making the rear flange.

The guy I spoke to (John) seems very knowledgeable - I will be ordering from him in the next week or so. If anyone else doesn't have a propshaft already DaveMac is definitely worth a call. The phone number is 024 7668 3239

Robin