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driveshaft shortening/lenthening
luke2152 - 21/7/13 at 04:53 PM

Just started building a gbs zero mazda mx5 version. It seems with the diff mounted so the flange is central to the propshaft tunnel that the cv joints are offset to the left. (gbs did mention this as a problem depending on what model diff comes from the donor). Anyway it is 19mm offset and I'm pretty sure that is too much for the cv joints to take up. Can anyone recommend somewhere to shorten one driveshaft and lengthen the other at a reasonable price.
Incidentally I also need propshaft shortened but I imagine that is more easily accomplished.

spiderman - 21/7/13 at 05:09 PM

Here is one place that make custom driveshafts at around £160 a pair I believe.

http://www.berrisford.co.uk/index.php?cPath=45&osCsid=hd9g6tl64g1d8u1rfnl33it9h1

Minicooper - 21/7/13 at 05:18 PM

It's £160 for each driveshaft

Cheers
David

luke2152 - 21/7/13 at 05:46 PM

Cheers for info. Bloody hell thats not cheap! Might have to have a look for a diff/driveshaft combo that fits. Or find another way to make it fit!

Minicooper - 21/7/13 at 05:56 PM

I would expect GBS should have a solution to this, hopefully a bit cheaper than custom drive shafts.

The diff flange could be offset depending on the diff mounting, to at least reduce the problem to a point where the standard drive shafts could do the job. The diff flange doesn't have to be absolutely central to the prop tunnel

Cheers
David

liam.mccaffrey - 21/7/13 at 06:15 PM

I'm sure you could get around this without modding shafts.

can you source another short one and use a flange spacer to make the 19mm on one side

can you centralise the diff and move the problem further up the drive train where it might be cheaper/easier to solve.





[Edited on 21/7/13 by liam.mccaffrey]

Slimy38 - 21/7/13 at 06:30 PM

quote:
Originally posted by luke2152
(gbs did mention this as a problem depending on what model diff comes from the donor).


Sorry to jump in on this thread, but do GBS give any more details about which are the troublesome diffs?

Is there any reason why you can't change your diff to one that isn't offset? (edit: ignore this one, a bit of Googling shows it's not that simple!)

Or as David says, can you mount the diff across a bit?

[Edited on 21/7/13 by Slimy38]

l0rd - 21/7/13 at 06:49 PM

isn't there a difference between the MX5 LSDs viscous, torsen and open?

I believe one of them is a bit offset compared to the others?

luke2152 - 21/7/13 at 07:00 PM

I'd post a picture but I can't figure out how...
GBS said they can have them shortened/lengthened didn't give a price and it came up in the same conversation as shortening the propshaft and lengthening steering column. I actually wasn't paying that much attention but I thought they said it the other way around as in that the driveshafts might be different lengths while the diff sits central. Rather then the driveshafts being same and the diff outputs offset (although the diff body is central).
There is no way of moving the diff without significant chassis mods - the clearance in the tunnel is pretty tight anyway.
The outputs stubs are not actually flanges but cups for the cv joint. Not sure if they can be removed and swapped for flanged stubs.
I will contact gbs and get a price (they will probably take 2 weeks to get back to me!) but I think best bet is going to be to source a diff and shafts which fit without alterations.

Slimy38 - they didn't say which ones to watch out for. The mazda version is new and not enough have been built to get things properly sorted. There are perhaps 10 different diffs in circulation. Btw if you are going to buy a mazda zero send me a u2u for a heads up because there are more non donor parts required then I was led to believe when I ordered....

liam.mccaffrey - 21/7/13 at 07:48 PM

I have 2 mx5 open diffs if that helps, wouldn't want much for 1.
I could take dimensions also if that helps you in any way

luke2152 - 21/7/13 at 08:06 PM

quote:
Originally posted by liam.mccaffrey
I have 2 mx5 open diffs if that helps, wouldn't want much for 1.
I could take dimensions also if that helps you in any way


Mine is open 7" one so may be the same...but dimensions are always good...
Firstly is it flange stubs or cv joint stubbs for the outputs (I wonder if these are interchangable?)
And also if they are equal distance from the diff centre.
Cheers

Slimy38 - 21/7/13 at 09:04 PM

quote:
Originally posted by luke2152

Slimy38 - they didn't say which ones to watch out for. The mazda version is new and not enough have been built to get things properly sorted. There are perhaps 10 different diffs in circulation. Btw if you are going to buy a mazda zero send me a u2u for a heads up because there are more non donor parts required then I was led to believe when I ordered....


Thanks for the offer, but I'm building a Haynes roadster so hopefully I only need to keep an eye on what donor I end up with and build to suit. At the moment I've not built anything behind the seat backs so I can basically build around the donor parts.

I'm not regretting my decision to go down the MX5 route, but the small 'tweaks' here and there are starting to mount up... And I don't even have a donor yet!

luke2152 - 21/7/13 at 09:34 PM

quote:
Originally posted by Slimy38
quote:
Originally posted by luke2152

Slimy38 - they didn't say which ones to watch out for. The mazda version is new and not enough have been built to get things properly sorted. There are perhaps 10 different diffs in circulation. Btw if you are going to buy a mazda zero send me a u2u for a heads up because there are more non donor parts required then I was led to believe when I ordered....


Thanks for the offer, but I'm building a Haynes roadster so hopefully I only need to keep an eye on what donor I end up with and build to suit. At the moment I've not built anything behind the seat backs so I can basically build around the donor parts.

I'm not regretting my decision to go down the MX5 route, but the small 'tweaks' here and there are starting to mount up... And I don't even have a donor yet!


It wont matter what diff you use on a roadster because the offset is small enough you can easily build around it.

Mikef - 22/7/13 at 07:55 AM

Try speaking with Nigel at Chard and sons 01179717341. They have been doing it for years, first class work and good fair prices.

MikeF

rdodger - 22/7/13 at 08:10 AM

When I spoke to GBS some time ago they mentioned using 2 of the same side driveshaft to make the diff fit. I presume 2 shorter ones?

As far as I am aware the only different diff in any MK1-MK2 MX5 is the early MK1 1.6. The rest are all the same.

luke2152 - 22/7/13 at 06:48 PM

Right GBS want £208 plus vat per shaft....!
Waiting on emails form Berris and Chard engineering.
I might yet chop and change the chassis...which would be a shame since the powdercoat looks great...

Mikef - 23/7/13 at 06:47 AM

Be interesting to see what the other quotes come in at.

MikeF

luke2152 - 29/7/13 at 10:57 PM

Update - dodds engineering came back with best price of £100 per shaft for new ones made to spec when I'm ready. I'm still a little unsure of how accurate I have to be measuring them up and how much the inner cv joint can take up. It looks like the left one is almost about right. The right one is clearly too short by about 20mm.

Mikef - 30/7/13 at 06:38 AM

Would have thought that was a good price.Will keep a note of them.

MikeF

mark chandler - 30/7/13 at 06:56 AM

I cut mine then sleeved with some 3/8" walled tube, mine are sierra.

Regards Mark

matt_gsxr - 30/7/13 at 09:57 AM

Back when Mel owned Raw I paid £65 for him to shorten my driveshafts (about 5 years ago). A good job he did too.

Raw has changed ownership but it might be a relevant price point.