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Flex disk trouble

Posted by Bob in Everett 
May 21, 2016 03:12PM
The cabrio has a smaller diameter flex disk than the sedan. My new S50 motor is more than the little guibo can deal with. 5000 miles and it needed replaced.
Has anyone developed a replacement for such for a cabrio? Not sure what the issues may be. There may be volume integration issues with the larger diameter. For sure would have to modify the drive shaft. It has some kind of a cylindrical damper just back of the guibo. The damper has a rubber element between the large diameter cylinder and the drive shaft. If that damper were not there, I wonder what the consequences would be? Also if the guibo were replaced with a universal joint, would it cause damage to the transmission or differential? Would I need a different transmission to get a universal joint to fit or is there one that could replace the existing spider with the three bolts on it?

Opinions welcome,

Bob in Everett
May 21, 2016 04:04PM
Quote
Bob in Everett
The cabrio has a smaller diameter flex disk than the sedan. My new S50 motor is more than the little guibo can deal with. 5000 miles and it needed replaced.
Has anyone developed a replacement for such for a cabrio? Not sure what the issues may be. There may be volume integration issues with the larger diameter. For sure would have to modify the drive shaft. It has some kind of a cylindrical damper just back of the guibo. The damper has a rubber element between the large diameter cylinder and the drive shaft. If that damper were not there, I wonder what the consequences would be? Also if the guibo were replaced with a universal joint, would it cause damage to the transmission or differential? Would I need a different transmission to get a universal joint to fit or is there one that could replace the existing spider with the three bolts on it?

Opinions welcome,

Have you googled this? There must be hundreds of E30s running S50 engines. I would certainly have a guibo as a weak link in the system, and to take up some slack in the driveline.
May 21, 2016 04:19PM
Ove,
I have not seen any S50 mods in cabrios myself. Mostly coupes.
The cabrio body is different than the sedan and coupe. I have not googled it. Probably should look in the R3V website though.

The E-30 picnic is coming up in a month where there will be over 200 other E-30 there. I may be able to find an opinion there. Probably should take some pictures from under the car to compare with coupes.

Thanks,

Bob in Everett
May 23, 2016 04:09PM
Quote
Bob in Everett
Ove,
I have not seen any S50 mods in cabrios myself. Mostly coupes.
The cabrio body is different than the sedan and coupe. I have not googled it. Probably should look in the R3V website though.

The E-30 picnic is coming up in a month where there will be over 200 other E-30 there. I may be able to find an opinion there. Probably should take some pictures from under the car to compare with coupes.

Thanks,

I never went into S-50 or Cabrio territory, but still is there a very good reason for the Cabrio to be different from other e30?
Can the S50 solution be adapted into the existing driveshaft?
Going u-joint I believe is a step back, there must be some reason why BMW don't use that in any car. Just a thought.
Maybe someone else from the S-50 people had to deal with it and came up with a good solution.

Keep us posted!
:wavey:
May 23, 2016 04:31PM
Have you read this thread?
[www.r3vlimited.com]
May 23, 2016 11:06PM
There are some good clues there Ove. Thanks. I am hoping to not have to change the whole transmission. Maybe just the output flange and the drive shaft forward end.
I need to get under the car and see if there is room for a larger diameter guibo. My cabrio drive shaft has a vibration damper on the forward end that may have to be removed to change to the larger flange. I had the flange off to change the rear seal when I had the transmission out but do not know if the E-36 size will fit the same spline. Probably will have to hang out at the salvage yard to find the right combination of parts.

Bob in Everett
September 05, 2016 08:18PM
I have re-read the link and still am not sure what some of the comments mean. After looking at the latest failed Guibo today (the second one), it appears that I may have installed it backward. I had a discussion with a guy at Oktoberfest about it and he was explaining how to install them and that failures he has seen have been installed backward. The arrows I have seen on them before are not in evidence on this one so had little idea which way it was supposed to go and it looked symmetric to me when I put it on. What I see there now does not look quite as symmetric as I remember.

The discussions I had also related to having the transmission located in alignment with the center support bearing so that there is a minimum of deflection to begin with.
Not having a hoist to work under the car, rolling around under it is not a lot of fun.

Bob in Everett
October 21, 2016 08:39PM
After puzzling for a few days over how to tell if the drive shaft and transmission are aligned, realized that what I needed to do was remove the guibo and insert the drive shaft studs into the trans mission coupling half. This gave me three points on the circumference to check the space between them. I found that the angle between them was close to 2 degrees. It appeared to be over 1/16 of an inch different top to bottom.

After loosing all the motor mounts and shimming the front mount on one side, was able to get the back end of the transmission into alignment. The problem I have now is it requires modifying my trans mount or fabricating a new one to hold it in that position.
I need to be sure it has more adjustment and possibility of shimming. An example from the web is attached. I need something like it.

Bob in Everett
Attachments:
open | download - Trans mount.JPG (79.7 KB)
November 15, 2016 11:41PM
So, I did make a new transmission mount but the location needed was such that i had to force the transmission to one side quite a bit. I think the motor mounts are the problem. They must not be exactly the right place. Anyway, to get the transmission to stay where it should be, I had to send off to Pelican parts and get some urethane mounts. The stock mounts are too flexible to hold it. Now it is close enough I am willing to give it a try. Seems ok so far, a few thousand miles will tell the story long term.

Good to have it back on the road again...too bad the nice weather is over. I put the hardtop on in preparation for the frost likely in a couple of days.

:biggrin:

Bob in Everett
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