Fiat TC auxiliary shaft bearings.

Question and answer direct with GC. Competition engines and 'live' projects only. Good photos to illustrate your post are expected.
Post Reply
Piotrek125p
Posts: 210
Joined: Sun Dec 02, 2012 3:45 pm
Location: Lodz,Poland
Contact:

Fiat TC auxiliary shaft bearings.

Post by Piotrek125p » Sun Jan 03, 2016 9:52 am

Hi.

GC, please tell me what is the biggest clearance between auxiliary shaft bearing and journal that didn't cause a oil pressure loss etc. For 3 years I measured about 10 Fiat TC blocks and most of them has this clearance out tolerance (I'm a metrologist). The owners often replace an old bearings, but this is a bit tricky operation and if I remember correctly You don't advise this operation.
The problems with too big clearance between aux shaft and bearings and oil pressure loss is one of the major disadvantages of Fiat TC and make this fabolous engine not popular in Poland.

Sincerely.
Piotr.
GC approved

Guy Croft
Site Admin
Posts: 5005
Joined: Sun Jun 18, 2006 9:31 am
Location: Lincoln, UK
Contact:

Re: Fiat TC auxiliary shaft bearings.

Post by Guy Croft » Sun Jan 03, 2016 12:03 pm

if the shaft is close to factory limits and the bearings are not ruptured leave it all alone!

I have changed the bearings in the past and reamed them with the factory tool and achieved no better fit than was there in the first place.

I pack up the Fiat relief valve springs (not the Lancia ones!) for extra pressure if using oil cooler etc to compensate for the line pressure-drop but have never seen low oil pressure in one of my units from the aux driveshaft.

G
Guy Croft, owner

Piotrek125p
Posts: 210
Joined: Sun Dec 02, 2012 3:45 pm
Location: Lodz,Poland
Contact:

Re: Fiat TC auxiliary shaft bearings.

Post by Piotrek125p » Sun Jan 03, 2016 12:16 pm

Ok, I will choose an aux shaft with best journals and use it. The bearings has a minor scorings, but I will dress it with Scotchbrite us You wrote in new book and it will be ok.

The hardened washer for relief spring is waiting for oil pump build up, of corse with thickness us You suggest.

Thanks GC.
GC approved

Guy Croft
Site Admin
Posts: 5005
Joined: Sun Jun 18, 2006 9:31 am
Location: Lincoln, UK
Contact:

Re: Fiat TC auxiliary shaft bearings.

Post by Guy Croft » Sun Jan 03, 2016 12:21 pm

POST SOME PHOTOS PLEASE!

GC
Guy Croft, owner

Piotrek125p
Posts: 210
Joined: Sun Dec 02, 2012 3:45 pm
Location: Lodz,Poland
Contact:

Re: Fiat TC auxiliary shaft bearings.

Post by Piotrek125p » Sun Jan 03, 2016 12:23 pm

Ok, on wednesday I have a free time so I pick here a photos of my bearings, measurings etc.
GC approved

Piotrek125p
Posts: 210
Joined: Sun Dec 02, 2012 3:45 pm
Location: Lodz,Poland
Contact:

Re: Fiat TC auxiliary shaft bearings.

Post by Piotrek125p » Wed Jan 06, 2016 2:12 pm

As I promised today I show my aux bearings. I haven't done today a measurements because it is too cold. But from memory I remember that bearing has:

-front (48,095-48,121mm)
-rear (42,071-42.085mm)

Front bearing photo. A damages are marked by arrows. I didn't found any cracks, so if it could work in my engine I will dress it with split fork+grey Scotchbrite and a looot of WD40. On one photo I showed a "nasty" bearing damage that I want to fix with split fork and Scotchbrite to avoid a bearing cracking in next service.
P1050972.JPG
Front aux bearing 1st photo
P1050972.JPG (105.4 KiB) Viewed 2126 times
P1050973.JPG
Front aux bearing 2nd photo
P1050973.JPG (115.76 KiB) Viewed 2126 times
P1050970.JPG
Front aux bearing 3rd photo (arrows shows a bearing damages)
P1050970.JPG (80.22 KiB) Viewed 2126 times
P1050974.JPG
Front aux bearing 4rd photo (arrow shows one nasty damage, I want to fix it with grey Scotchbrite and split fork to avoid cracking in service)
P1050974.JPG (134.54 KiB) Viewed 2126 times
Of corse I also made a rear bearing photo, but it is a bit tricky job and this is not best photo on the world
P1050978.JPG
Reaer aux bearing photo
P1050978.JPG (101.4 KiB) Viewed 2126 times
GC, what do You thinking about all this stuff ?
GC approved

Piotrek125p
Posts: 210
Joined: Sun Dec 02, 2012 3:45 pm
Location: Lodz,Poland
Contact:

Re: Fiat TC auxiliary shaft bearings.

Post by Piotrek125p » Sat Jan 09, 2016 12:05 pm

Today I did some measurements in properly enviroment (21,3 degree Celsius) and I got:
-front bearing (48,118-48,148).
-rear bearing (39,018-39,034).
The rear bearing is ok and I get a good clearance, but a front clearance is about 0,098-0,128. I done some trial fit with my aux shaft and I feel it is really loose.
GC approved

FiatRally
Posts: 65
Joined: Mon Feb 11, 2013 6:37 pm
Location: Cape Town. South Africa
Contact:

Re: Fiat TC auxiliary shaft bearings.

Post by FiatRally » Thu Jan 28, 2016 1:06 pm

Hello Gentlemen,

I have bearings in stock in Cape Town, South Africa.

Most front bearing damage is caused by over tightened cam belt tension!

But it is to ream them to spec once they are fitted that is the problem!

I do not have tools to do this. We do the best we can with the tools we have.

If you need bearings contact me Guy.

Regards.
GC_75

Guy Croft
Site Admin
Posts: 5005
Joined: Sun Jun 18, 2006 9:31 am
Location: Lincoln, UK
Contact:

Re: Fiat TC auxiliary shaft bearings.

Post by Guy Croft » Thu Jan 28, 2016 8:16 pm

Piotr,

with oil in place that clearance is nothing to worry about, trust me, just build it.

G
Guy Croft, owner

Piotrek125p
Posts: 210
Joined: Sun Dec 02, 2012 3:45 pm
Location: Lodz,Poland
Contact:

Re: Fiat TC auxiliary shaft bearings.

Post by Piotrek125p » Thu Jan 28, 2016 8:41 pm

Thanks GC for Your reply. I have a shaft with diameters at the upper tolerance from my 1585 and I will use it.
Are a GC style of "reconditioning" of aux bearings is lightly dressing it with grey Schotchbrite + eg.Jizer or something more ? Reading your book I got the impression that this is enough.
GC approved

Guy Croft
Site Admin
Posts: 5005
Joined: Sun Jun 18, 2006 9:31 am
Location: Lincoln, UK
Contact:

Re: Fiat TC auxiliary shaft bearings.

Post by Guy Croft » Thu Jan 28, 2016 9:33 pm

yes Piotr

that is enough, hold the Scotchbrite pad tight on the journals with some Jizer and turn the shaft with a low-speed drill with a bolt in the end and 19mm socket and spin the shaft in direction of rotation ..

Whether you use 'red' (fine) or dark green (coarse) 3M Scotchrite only depends on the condition of the journals - if they are unmarked use fine grade..

be sure to cut off the fuel lobe and plug it off and clean the oil gallery very thoroughly...

G
Guy Croft, owner

Piotrek125p
Posts: 210
Joined: Sun Dec 02, 2012 3:45 pm
Location: Lodz,Poland
Contact:

Re: Fiat TC auxiliary shaft bearings.

Post by Piotrek125p » Thu Jan 28, 2016 9:55 pm

The condition of my bearings You can judge personally by photos attached by me. It is looks that I should use dark green and red, my bearings has some minor damages.

I will cut off a fuel lob, no doubt.
GC approved

Guy Croft
Site Admin
Posts: 5005
Joined: Sun Jun 18, 2006 9:31 am
Location: Lincoln, UK
Contact:

Re: Fiat TC auxiliary shaft bearings.

Post by Guy Croft » Thu Jan 28, 2016 10:00 pm

Journals Piotr,

not bearings!!!!!!!!!!!

The bearings - light clean with fine Scotchbrite only...

G
Guy Croft, owner

Piotrek125p
Posts: 210
Joined: Sun Dec 02, 2012 3:45 pm
Location: Lodz,Poland
Contact:

Re: Fiat TC auxiliary shaft bearings.

Post by Piotrek125p » Thu Jan 28, 2016 10:05 pm

My oversight, sorry GC.

A journals are in excellent condition, so I will use only fine Scotchbrite, they looks like a new.
GC approved

Guy Croft
Site Admin
Posts: 5005
Joined: Sun Jun 18, 2006 9:31 am
Location: Lincoln, UK
Contact:

Re: Fiat TC auxiliary shaft bearings.

Post by Guy Croft » Thu Jan 28, 2016 10:35 pm

OK!
Guy Croft, owner

Post Reply

Who is online

Users browsing this forum: No registered users and 1 guest