Balance issues?

Post Reply
User avatar
Terafrost
Gold
Gold
Posts: 60
Joined: Thu Sep 17, 2009 7:43 am
Location: Hobart, Tasmania (AUS)

Balance issues?

Post by Terafrost » Thu Jul 25, 2013 12:15 am

Hi all,

Just wondering if anyone has had any balance-related issues in the arse end after bolting a twinspark 'box in? A mate of mine has broken two front clutch housings in successive tarmac events and is understandably sick of trying to find replacements.

Here's what I know;
- He's running an all-but standard 2.5L (S-cams & PACE Headers) and factory rev limit.
- His mechanic can't recall whether a V6 or 4cyl clutch was used.
- The 'box has the early shift mechanism installed (not sure if relevant)
- Donuts are all less than 5,000km old, same with the centre bearing support and all mounts.

Can anyone point out where the issue might stem from?

I've heard of them breaking due to the use of single-piece driveshafts (I assume this would have been poor balance rather than the change from a two-piece) but there aren't many serious Alfas down here to compare with.
Alex

1985 GTV6
1983 GTV6 - Project
1985 ALFA 90 GCL - in many, many pieces... Anyone?
1987 ALFA 75 TwinSpark - Now running around Victoria.
User avatar
Mats
Verde
Verde
Posts: 4059
Joined: Mon Nov 29, 2004 12:26 am
Location: Gothenburg, Sweden
Contact:

Re: Balance issues?

Post by Mats » Fri Jul 26, 2013 12:51 pm

Front mounts are different on the V6/Turbo vs. 4-cyl, but I guess it should be fine unless some monkey has fitted solid mounts on the wrong type of clutch...

So, are there any modifications done to the install? I mean even stuff that "is a must and everybody does" that usually no-one has even heard about in a neighboring country. ;)
Mats Strandberg
-Scuderia Rosso- Now burned to the ground...
-onemanracing.com-
-Strandberg.photography-

GTV 2000 -77 - Died in the fire.
155 V6 Sport -96 - Sold!
smashigcraft
Silver
Silver
Posts: 10
Joined: Tue Dec 18, 2007 8:40 pm

Re: Balance issues?

Post by smashigcraft » Mon Jul 29, 2013 1:36 am

Thanks for your interest Mats (owner of the vehicle here)

The car has a twinspark box however I think the housing is original. It has done 3-4 tarmac rallys with no change of setup.
There has always been a vibration especially at high revs in first and second.
Clutch is definately v6.
Do you think a shaft balance, replacement of bearing and all donuts is a good start?
kevin
Verde
Verde
Posts: 2762
Joined: Sat Jan 22, 2005 9:09 am
Location: Esher, UK

Re: Balance issues?

Post by kevin » Mon Jul 29, 2013 3:35 pm

The clutch housing is a weak point especially on Tarmac rallying as it takes more abuse than the track . I do know of three to four housings that broke due to balance issues on prop , bad bearings in housing and these were not even on high horse power motors and revs were at max 6500pm . Some of these were 2.0 and others were v6 . . If you reinforce housing and do all what you mentioned above you " should" be ok . Md showed us all how to reinforce housings which I copied and worked very well on my 3.7 and is currently on another 3.2 with a twinspark gearbox . Also check the sleeve in the top of housing is not worn or loose .
Once you have assembled clutch into housing check for play . ( hold one section in vice )
Did the housing break suddenly on a down change into second or a change up between second and third .
Attachments
image.jpg
image.jpg (155.45 KiB) Viewed 2951 times
image.jpg
image.jpg (163.9 KiB) Viewed 2951 times
User avatar
Terafrost
Gold
Gold
Posts: 60
Joined: Thu Sep 17, 2009 7:43 am
Location: Hobart, Tasmania (AUS)

Re: Balance issues?

Post by Terafrost » Sun Aug 04, 2013 12:33 am

I'll have to check about the timing of the breakage. Thanks for the photos, Kevin - I'll certainly be recommending reinforcing the unit.

I got under the car (very briefly) today and noticed that the deDion was missing the spacers under the crossmember. Could this have caused enough wear over time to throw something out of place? Surely a 10mm+ difference in height would cause issues? Still haven't checked the gearbox mounts. So there's potential for an even bigger difference in height, depending on which mounts are in there

Thoughts?
Alex

1985 GTV6
1983 GTV6 - Project
1985 ALFA 90 GCL - in many, many pieces... Anyone?
1987 ALFA 75 TwinSpark - Now running around Victoria.
User avatar
Mats
Verde
Verde
Posts: 4059
Joined: Mon Nov 29, 2004 12:26 am
Location: Gothenburg, Sweden
Contact:

Re: Balance issues?

Post by Mats » Sun Aug 04, 2013 10:51 pm

Misaligned guibos will create quite a bit of straightening torque (as in trying to force the propshaft straight) when you spin them so, yes, that might be part of the problem.
While you're in there, try to fit the propshaft as straight as possible even if it means you need to move the engine and gearbox a bit.
Mats Strandberg
-Scuderia Rosso- Now burned to the ground...
-onemanracing.com-
-Strandberg.photography-

GTV 2000 -77 - Died in the fire.
155 V6 Sport -96 - Sold!
User avatar
Terafrost
Gold
Gold
Posts: 60
Joined: Thu Sep 17, 2009 7:43 am
Location: Hobart, Tasmania (AUS)

Re: Balance issues?

Post by Terafrost » Mon Aug 05, 2013 4:42 pm

Thanks Mats.

Pardon my ignorance, but how much movement are you talking about regarding engine/gearbox? Do you mean whatever is allowed with the standard mounts in place? I.e. loosen/unbolt during installation?
Alex

1985 GTV6
1983 GTV6 - Project
1985 ALFA 90 GCL - in many, many pieces... Anyone?
1987 ALFA 75 TwinSpark - Now running around Victoria.
User avatar
Mats
Verde
Verde
Posts: 4059
Joined: Mon Nov 29, 2004 12:26 am
Location: Gothenburg, Sweden
Contact:

Re: Balance issues?

Post by Mats » Wed Aug 07, 2013 12:21 am

Yeah, that's the first step. If you need further movement (probably) you'll have to decide wether you want to or not. But from a guibo-life point of view there are PLENTY of cars racing without moving the engine/gearbox around so there is maybe another issure somewehere.
Still worth thinking about though.
Mats Strandberg
-Scuderia Rosso- Now burned to the ground...
-onemanracing.com-
-Strandberg.photography-

GTV 2000 -77 - Died in the fire.
155 V6 Sport -96 - Sold!
User avatar
Mark Walshaw
Gold
Gold
Posts: 131
Joined: Mon Apr 18, 2011 2:51 am
Location: Formerly Cape Town,now Gangsters paradise

Re: Balance issues?

Post by Mark Walshaw » Mon Apr 23, 2018 3:09 am

Hi All, have not been on for a while. Picked up a problem, I replaced the front prop shaft coupling on my GTV6. I received the coupling from Highwood.
All went in fine, kepynall bolts and washers in the correct order. On starting it has a wicked vibration from idle up to about 2500 rpm.
Any easy fixes or do I take it out and have it all re balanced.
User avatar
75evo
Verde
Verde
Posts: 812
Joined: Tue Oct 11, 2005 8:56 am

Re: Balance issues?

Post by 75evo » Mon Apr 23, 2018 9:04 am

Do you have the splined front yoke on the driveshaft? If you do some people have had good luck by loosening the punch bolt and letting it idle.

The cheap way to do it would be to use hose clamps and and adjust it until the vibration reduces.

That's not the best way to do it. You could do that for now until you have time to take it to a proper balancing shop.
User avatar
Giuliettaevo2
Verde
Verde
Posts: 769
Joined: Sun May 08, 2005 11:56 pm
Location: Netherlands

Re: Balance issues?

Post by Giuliettaevo2 » Mon Apr 23, 2018 10:46 am

Make sure the centering bush is in good condition and fits nice in the flywheel.

I always leave the bolts loose, start and run the engine a while and then stop the engine to tighten the bolts.
Drive it like you stole it...
105gta.
Gold
Gold
Posts: 53
Joined: Fri Oct 23, 2015 4:15 am

Re: Balance issues?

Post by 105gta. » Fri Jun 15, 2018 1:37 am

Hi all, an old subject I know but just a heads up! The 4 cyl cars nd v6 have a diff size input shaft sleeve. (The tube the throw out bearing slides on) so if you simply bolt a v6 clutch housing and flywheel assembly onto a twinspark g/box you'll have the larger bearing on the smaller tube. Which causes weird vibrations.
The tubes themselves are interchangeable so not a problem but just be sure that you make sure all parts are a match.
Post Reply