Throwout bearing differences between 520 and 523

[moparman76_69]

When I was putting the van together I went from the original 520 to a later model 523. I didn't have the throwout bearing from the 523 so I just stuck the one from the 520 on there and called it good until I got everything installed and then noticed that the clutch arm was pivoted down too far for the cable to fit, so I ended up changing the arm out with the one from the 520 also. I've driven it like that for a year but now I need a new TOB and noticed the older part number is different. What is really different about them and since I've used the 520 one and it works should I just use a replacement for it or should I use a 523 TOB?

[moparman76_69]

So nobody knows the differences?

[Ondonti]

I have seen that the big beefy ones for the newer trans seem more fail prone in the bearings department. They want to start making lots of noise.

I only have found that the a543/a523 style bearings seem to be the same while the clutch arms and cable lengths changed over time.

[moparman76_69]

So I was thinking that the real difference would have to be in relation to the clutch arm. Since I had to change the arm when I used the 520 bearing, so it apparently works the way it is and I shouldn't try and change everything up at this point and just get a new 520 TOB.

[135sohc]

The intrusion of the larger front pinion bearing pocket into the bellhousing on the 523 vs the 520 is also a factor.

[Ondonti]

So I was thinking that the real difference would have to be in relation to the clutch arm. Since I had to change the arm when I used the 520 bearing, so it apparently works the way it is and I shouldn't try and change everything up at this point and just get a new 520 TOB.

You can also get the longer or shorter cable (but hard to tell what you are getting). The factory cable I bought matched up with the newest style arm.

[Shadow]

Only difference I've ever noticed is the thinner mounting wire on the 523/568 vs the wider steel bands that mount the 520/555. I have a 520/555 in my 568 right now, but I had to grind the two steel bands down so they were thinner in width to work properly.

The 520/555 also has a large steel plate that mounts the bearing, while the 523/568 is almost just bearing.

[135sohc]

523/568/543? bearing:

33903

520/555/525? bearing
http://www.turbo-mopar.com/forums/attachment.php?attachmentid=33815&d=1315362901


Look at the spacing difference the bearing pocket and the input shaft seal retainer. Go one further and compare the spacing difference between the edge of the TOB and bearing pocket. On the 523 the gap between the TOB and bearing pocket is about 1/8-3/16" with a stock bearing.

[Shadow]

Not sure what you guys are talking about, so I took some pics side by each. Like I said, the only difference I noticed was the lack of large metal plate from the one to the other + the thin wire retainer because the new style trans has a grooved TOB fork arm to recieve the wire.

135sohc, I think the difference your showing is not the bearings but the difference in the two cases as the later 568/523's got a larger output shaft bearing so the case has less clearance there? That difference in clearance is also the reason the 555 bearing won't just slide in without modding.

[moparman76_69]

I just slid the 520 one on there as is and until a couple of weeks ago had no issues. My main reason for asking was to make sure it didn't go bad because of the fact that I used the "wrong" one.

[Shadow]

I just slid the 520 one on there as is and until a couple of weeks ago had no issues. My main reason for asking was to make sure it didn't go bad because of the fact that I used the "wrong" one.

Shouldn't be any issues. Surprised it just "went on"? Did it have the metal "straps" like in the pic I posted, or did it have wire like the other one has?

[135sohc]

That difference in clearance is also the reason the 555 bearing won't just slide in without modding.

Which was the point I was trying to make. Since the question was brought up why the two different units used two different TOB's and theres a real reason for it.


I just slid the 520 one on there as is and until a couple of weeks ago had no issues. My main reason for asking was to make sure it didn't go bad because of the fact that I used the "wrong" one.

That could have very well been a contributing factor. once its installed and all buttoned up things move around and if it was binding and always staying semi loaded while spinning around that could have contributed to an early failure. Shadow said he had to moddify the 520/555 bearing to fit his 568, I assume he removed some metal from the one side so it would contact the case and bind up.

[moparman76_69]

Shouldn't be any issues. Surprised it just "went on"? Did it have the metal "straps" like in the pic I posted, or did it have wire like the other one has?

yeah it went on but now that I think about it it didn't sit perfect probably because of what you said with the grooves in the fork, I ordered a new 520 bearing because they're cheaper and I'll mod it to fit.



That could have very well been a contributing factor. once its installed and all buttoned up things move around and if it was binding and always staying semi loaded while spinning around that could have contributed to an early failure. Shadow said he had to moddify the 520/555 bearing to fit his 568, I assume he removed some metal from the one side so it would contact the case and bind up.

I'll have to mock it up and make sure it doesn't sit sideways because of the case. I thought it always contacted the PP, at least I'm sure it does now because I'm sure it locked up and is scraping against the fingers.

[Shadow]

Which was the point I was trying to make. Since the question was brought up why the two different units used two different TOB's and theres a real reason for it.


Sorry bro, my bad. I started reading ppl talking about having to change cables/pivot arm/forks ect and I thought they were talking about the difference in the two bearings and I thought you were doing the same. (thinking the bearings were quite different)

[135sohc]

yeah it went on but now that I think about it it didn't sit perfect probably because of what you said with the grooves in the fork, I ordered a new 520 bearing because they're cheaper and I'll mod it to fit.



I'll have to mock it up and make sure it doesn't sit sideways because of the case. I thought it always contacted the PP, at least I'm sure it does now because I'm sure it locked up and is scraping against the fingers.

The TOB is always in contact with the pp fingers but if its jamming up and really pressing into the fingers it would be like always having the clutch pedal pushed in. constantly loaded and its gonna burn out eventually.