I have a '67 124 Sedan. Mechanically very close to the early 124 Spiders. I have owned this car for about 8 years but in the last year I starting putting more work into it. So, I am starting this thread to keep track of the work and hopefully help out other Sedan owners.

To get us all caught up here is a recent pic:


Highlights over the last year include installing electric cooling fans, Mark's Fiat 500 brakes and some turbo wheels and replacing the very tired 1197cc pushrod motor with a 1608 DOHC, I got the long block free from a site member.

Now that we are caught up lets get into the current project. My sedan originally came with a 4spd transmission and 4.30 rear. Providing an intense +4K RPM on the highway, no fun. There is no shift extension on these cars so the Fiat Spider 5spd does not fit without cutting up the trans tunnel. I like a more original look so that leaves me with interesting mods:
http://www.seat124.com/showthread.php?5 ... in-torreta
http://www.seat124.com/showthread.php?1 ... on-torreta
A Fiat Polski transmission or a Lada 5spd.
The Lada 5spd has the shifter in the same place as the 4spd. Added bonus of the Lada trans is a .82 5th gear. djape managed to track one down for me. Here is a picture of the Fiat 4spd, Lada 5spd and Fiat 5spd:



And finally the Lada 5spd with the 1438 bell housing ready to go into the car:


When I upgraded to the Lada 5spd I also decided to refresh the torque tube driveline, even though there was no vibration its history was a mystery to me. I had the driveshafts straightened and balanced. I also replaced the guibo, output shaft bush, center support bearing and rubber.

After all this there is a low speed vibration that builds until around 50MPH, then at higher speeds it smooths out, or at least gets better.

I've been reading about driveshaft balancing, alignment and phasing. Its pretty interesting, I learned that when spinning at an angle universal joints speed up and slow down as they turn. This video does a great job illustrating this:
https://www.youtube.com/watch?v=gmV4qwLfOMY
This means the transmission and pinion angle are important to prevent vibrations. With a typical Hotchkiss drive and two U-Joints this means the trans output shaft and rear end pinion have to be parallel and have some space between them. This page does a great job showing how to set that up:
http://www.hotrodhotline.com/md/html/dr ... monics.php

The torque-tube drive only has one U-joint, so its not possible to cancel out any u-joint misalignment. I can only find a sentence or two about how a torque tube drive shaft should be setup but if I am reading it right the transmission output shaft has to be in line and at the same angle as the axle pinion. Here are the references I've found:
http://www.jalopyjournal.com/forum/thre ... gle.17358/
http://jniolon.clubfte.com/drivelinepha ... asing.html

So, next trip to the garage I'll try to understand the vertical and horizontal alignment of the driveline. Open to any other ideas on what could cause the vibration!

I really like your project. The 14" Turbo wheels look really nice on that car and the 1608 is a great improvement. Will you be keeping the engine in stock configuration or building it for street or track performance?

Either way, it looks like you will be scaring the hell out of the BMW 2002 and Datsun 510 crowd with that rocket sedan. Awesome!

Where are you located?

Looking good Grrrdot, I'm watching with interest. Had a '72 sedan with 4 speed and 1438 pushrod as my daily driver and really liked it. A 1608 and a 5-speed with a numerically lower rear end will be really sweet. My '69 coupe also has a mild but persistent drivetrain vibration right at 4000 driveshaft RPM despite doing all the usual maintenance items and two rounds of balancing at a driveshaft specialty shop. I'll ponder the angles now and keep watching your thread.
Eric Van Nice

Thanks for the feedback!

Ramzi wrote:Where are you located?

Hi! I am in NYC. You and I have spoke a number of times over the years. You sold me a Fiat Shop Manual for the car back in 2010. I think last time we spoke you were looking at building up a wild sounding 1608 pushrod motor?
I never saw pictures of your Sedan though. RHD no less! I am jealous of your bumper overrides, your paint looks better too.

SunnySideUp wrote:Will you be keeping the engine in stock configuration or building it for street or track performance?

I actually don't know whats inside the 1608. I was told the motor had been rebuilt and stored as a backup, but the specs were unknown as the PO inherited it. The valves, springs and guides all looked brand new so I just went with it. In terms of ancillaries I used a bunch of parts I collected over the years. Notable ones are: 1438DOHC camboxes and lightened flywheel, 1800 intake, 32/36 DFEV, 2L FI exhaust and a Lancia Beta electronic distributor. Its a lot of fun in this configuration so I am trying to focus on fixing or improving other parts of the car.

raise the car on the lift with someone inside, get it running and slowly build up to gear/speed/rpm where vibration occurs, while you watch from below what's going on. that way you'll find the problem quickest.

in past couple months, i've been helping a friend from Thessaloniki , Greece, troubleshoot similar problem.
he had installed fiat 132 2000cc engine and gearbox into 125. because of bigger gearbox, he had propshaft shortened and balanced by a local shop that specializes in propshafts.
from day one there was a vibration present at certain RPMs. he had everything checked and double checked, changed some parts that seemed to be the problem, but things didn't improve. he took the propshaft off the car and brought it back to propshaft shop to re-check the balancing. they said it's fine and he installed it back.
after about a month of daily driving, the car developed knock in transmission. he chased the problem down to worn splines of gearbox output yoke and cracked rear gearbox housing!
i had to send him parts from Belgrade, Serbia, which was not cheap nor convenient. i told him the same thing i told you, get the car on the lift.
he replaced rear gearbox housing and output yoke and tested the car on the lift.
he called me at 11PM all excited that he had found the problem - first propshaft section was crooked. when they shortened it, they welded it back on crooked. as it rotated, all of front propshaft section was going up and down.
he tok the propshaft back to same specialist in the morning and insisted that he enters the workshop area to show them what's the actual problem. when installed in balancing machine, it was obvious that it was crooked. he pointed it to the guy working on balancing, and he said "but we balance it and it's fine"
f**** idiot actually believes that when you balance a bent or crooked rotating part, the problem goes away!!!
by the way, propshaft specialist failed to offer to cover the cost of parts and work destroyed by wobbling propshaft...

same thing as with wheels - you hit a pothole and bend a wheel. you take it to tire shop. they can balance it, no problem, the balancing machine will show them where to put the weights and all is well as far as balancing. but it will still wobble producing vibration.

djape1977 great post, thank you!

Whew.
Before getting started I used my go-pro to make videos of the drive-train spinning. I didn't see much, here is the video:
https://www.youtube.com/watch?v=gIegaSm4h9Q

I measured out the angles of the transmission, driveshaft and torque tube. The engine was around ~1˚, driveshaft at ~3˚ and torque tube at ~6˚. Here is a picture of measuring the driveshaft:


When I swapped in the 1608 I used the mounts that came with the motor, I believe they are from a Spider. These mounts put the engine very low in the car, almost touching the cross-member. So, I drilled a new set of holes in the mounts and raised the engine up about 3/4" of an inch. This puts the engine and transmission at ~3 degrees. As a bonus this put the exhaust down-pipe in a better location, moved the alternator away from the lower radiator hose and took stress off the guibo.

Unfortunately changing the angle of the engine didn't fix the vibration. So out came the dial gauge to check the front driveshaft run-out.


According to the Fiat manual the tolerance for the front driveshaft is .011" 50mm from the welds and .019" at the center. I measured run-out at the front as .008", middle at .013" and rear .021". At the rear the high and low points closely line up with the torque tube's yoke. I had the shafts straightened and balanced so this was disappointing.

On the suggestion of this article: http://www.hurst-drivelines.com/files/D ... on-FAQ.pdf I flipped the driveshaft 180˚. This brought the run-out to .013" with the high and low points in the same place. The hurst article says this means the driveshaft is bent. The vibration is much better but still present.


So, time to call the driveshaft place back. Since the run-out did improve does that mean the yoke is also bent?
I don't feel any play but I am wondering if the u-joint could be an issue as well?

ii don't think your problem has anything to do with angles.
actually, you can see that front section is wobling. also the yoke that connects propshaft to guibo.

u joints - two ways you need to test them.
pardon my clumsy explanation, but there are two ways U joints fail.

1) rotational slack - one hand on one propshaft section, other on diff coupling, guibo, other propshaft section. try to rotate them in diferent directions.
2) sideways slack - try to move propshaft section relative to whatever it's connected to in directions of "cross" of the U joint

any slack in either way means that u joint is fecked

also, check for slack between sliding yoke and propshaft. rotational and directional slack.

by the way, you should have told me that you needed front blinkers. i have new ones, for fenders and under headlights...

I actually have a spare turn-signal but that fender has so much bondo the studs are not long enough. So, I have a spare fender that will eventually go on the car.
The wobble at the yoke went away once the engine angle was setup correctly. I measured the wobble at the yoke to be .008" which is well in spec. ( .011" ) The problem is the back of the front shaft, near the center support bearing, its .021", almost double spec!
U-joint is tight no matter how you push on it.

I brought the torque tube and the front drive-shaft back to the shop and explained the front drive-shaft was bent. The guy at the shop wants to set the whole assembly up to straighten and balance it but he can't. The issue is the torque tube itself is the center bearing support and the rear shaft ends inside the torque tube. He does not have the equipment to support the tube and hook up to the shaft inside it. Here is the parts list for the torque tube setup:


So, I'm trying to come up with a way this guy could support the center bearing without the torque tube. The center bearing is the same for all 124 drive-lines so I think he could use a late model drive shaft support block instead of the tube just to straighten and balance. Once its straight and balanced up he would need to disassemble and re-assemble inside the torque tube.

So to try this I just need a drive-shaft support block like the one below:


-G

didn't you say you had a later model rear end ready to go onto your car? perhaps it's time to let go of torque tube?
i have zero experience with torque tubes, all cars with that setup over here were already converted to newer setup long before i started fiddling with fiats 20yrs ago

So while I am waiting for the drive-line place to straighten and balance the driveshafts its a great time to swap out the differential!

The current diff is a 4.3:1 ratio, a few years ago I snagged a used torque tube 4.1:1. To make things more interesting we'll use all new bearings and a torsen style differential. AR supplied the bearings, they are the same as the front load 124 differentials. The torque tube rears also use the same diff carrier as the front load 124 differentials so no custom machining necessary.
I did a bunch of research and narrowed it down to a unit from ladapower or VAL-Racing. In the end I decided to go with the val-racing unit as I could find more info on it. Here is the site:
http://www.val-racing.ru/catalog/samobl ... _2101_2123

The torsen I ordered is pretty light, only 50% with a 5.5kg preload. I hope it will provide some help without being to harsh around the city. I am wondering if I should have got a higher pre-load as I have read that it weakens as the unit wears. A friend in the Ukraine helped get the unit to me.

Pulled the spare diff apart:


Bearing and races looked fine, scribble on the pinion from almost 50 years ago for the shim size:


All setup and checked:


Diff installed:


Now I just need the driveshaft to get this rolling again.

didn't know early 124's had rear ARB.
i've seen anti roll bars like that but didn't know what they came off