| Author |
Message |
Paul Jeffery (Peajay)
Junior Member
Username: Peajay
Post Number: 81
Registered: 4-2002
| | Posted on Sunday, June 29, 2003 - 3:15 pm: | |
Hmmm.... interesting Dave, that sounds like really naughty stuff !! |
Dave Helms (Davehelms)
Junior Member
Username: Davehelms
Post Number: 66
Registered: 5-2003
| | Posted on Sunday, June 29, 2003 - 7:03 am: | |
Paul, I have been seeing a lot of what you are suggesting lately. There have been 2 cars this year where there was no question only the rear belt was replaced. In some minds, maybe that was a major service! A lot of scams in the recent year!! Both banks run the same, and should show the same age and wear, if there is no other problem present.
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Lawrence Coppari (Lawrence)
Member
Username: Lawrence
Post Number: 691
Registered: 4-2002
| | Posted on Saturday, June 28, 2003 - 3:35 pm: | |
My Dad used to say that to me - learning from the mistakes of others. I can also recall him asking me, "When are you going to learn....when you die?" |
Ali Haas (Aehaas)
New member
Username: Aehaas
Post Number: 40
Registered: 5-2003
| | Posted on Saturday, June 28, 2003 - 2:58 pm: | |
I will add that the factory service manual for the 550 and 575 states to tension a new belt then never touch it again. The only adjustment is to replace the belts.
aehaas
Smart people learn from their mistakes.
Really smart people learn from somebody elses mistakes. |
Verell Boaen (Verell)
Member
Username: Verell
Post Number: 889
Registered: 5-2001
| | Posted on Saturday, June 28, 2003 - 1:23 pm: | |
DELETED - posted to wrong thread. |
Paul Jeffery (Peajay)
Junior Member
Username: Peajay
Post Number: 78
Registered: 4-2002
| | Posted on Thursday, June 26, 2003 - 12:16 pm: | |
Good tip about the access to check belts on the 328, I haven't owned the car long enough to notice, but that is good to know. My old front belt looked more distressed than the rear one, I wonder if someone just changed the rear last time because it is easier, or maybe the front one runs hotter ? |
Verell Boaen (Verell)
Member
Username: Verell
Post Number: 876
Registered: 5-2001
| | Posted on Thursday, June 26, 2003 - 11:35 am: | |
BELTS ARE ANOTHER REASON FOR MAKING SURE THE CAR IS THOROUGLY WARMED UP BEFORE GOING WOT!!!
Larry, your mentioning the belt tension increasing with engine temp made me realise that it's another strong argument for a thorough warmup before WOT redlineing the engine! More tension implies reduced chance of jumping belt teeth!
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Dave Helms (Davehelms)
Junior Member
Username: Davehelms
Post Number: 63
Registered: 5-2003
| | Posted on Thursday, June 26, 2003 - 6:00 am: | |
According to Ferrari, you can retension the belts once within 500 miles of new. Take special notice to Verell's post and follow that advice! The only belts I have delt with that broke, have been retensioned ones. And that 500 mile thing, not worth the risk! Set them once with new tensioner bearings, and relax for 5 yrs or maybe 25k miles. That is if someone has not over tensioned them already and knocked out the belt drive gear bearings. Im starting to see quite a rash of failures on those now. |
Lawrence Coppari (Lawrence)
Member
Username: Lawrence
Post Number: 682
Registered: 4-2002
| | Posted on Thursday, June 26, 2003 - 5:58 am: | |
On a 328 you can feel the front belt tension very easily. Just run your fingers down the housing cover towards the drive pulley. Of course its tension depends on whether the cam shaft is trying to drive the belt or vice versa.
The belts are always tighter when engine is hot. Aluminum has a fairly large coefficient of thermal expansion. You can feel the front belt even if the engine is hot. The belt cover does not get to the same temperature as the block. |
John Millard (Jmillard308)
New member
Username: Jmillard308
Post Number: 20
Registered: 5-2003
| | Posted on Thursday, June 26, 2003 - 4:04 am: | |
I never check them, just replace them - twice in 4 years. Cheap insurance IMO |
Verell Boaen (Verell)
Member
Username: Verell
Post Number: 868
Registered: 5-2001
| | Posted on Wednesday, June 25, 2003 - 10:25 pm: | |
Guys,
The Ferrari manuals are pretty adamant about NEVER retensioning after the initial tension adjustment:
Workshop Manuals:
308GT4 Manual:"The tension of the toothed timing belt must only be set when first installing it. Any further re-adjustment is useless since the working clearance will reappear unchanged after a short time, while the resultant elastic strain, increasing at each re-adjustment, could result in the belt breaking after a few operations. Always replace the belt if it has to be removed in service"
308QV/328 Workshop Manual Supplement:
"- The tension adjustment of the toothed belts is done at the time of their original installation.
-Therefore, never readjust the belt tension as the original working play would reappear unchanged after a short time, and the deformation resulting from eventual adjustments, even only once, would cause a premature belt failure.
- For the aforesaid reasons, always change the driving belts when their removal becomes necessary
- ..."
Owner's manuals:
"Every 9,000mls check belt tension - In standard operating conditions it is not necessary to adjust the belts tension."
"From 27,000mls and not over 37,000mls replace belts."
The belt fiber strands are made of Kevlar which doesn't stretch up to it's yield threshold. (That's why it's used in bulletproof vests.) At the yield threshold it breaks.
IMHO: If a belt is 'stretched' it's because some of the kevlar strands have broken & the belt is headed toward failure. |
Paul Jeffery (Peajay)
Junior Member
Username: Peajay
Post Number: 77
Registered: 4-2002
| | Posted on Wednesday, June 25, 2003 - 3:55 pm: | |
How did you know the front belt was loose ? did you remove the cover ?
I also have the impression that the front bank is slightly different, I had a tough time geting the front belt on compared to the rear, and after setting the tensioner the belt still seems to be a tad looser than the rear. It seems logical to me to go in after a while and release the tensioner bolts to take up initial slack. |
Newman (Newman)
Intermediate Member
Username: Newman
Post Number: 1202
Registered: 12-2001
| | Posted on Wednesday, June 25, 2003 - 3:38 pm: | |
During the engine rebuild on my 308, I set belt tension on the stand but after 1000kms, the front belt was loose. I reset it. I think the geometry of belt tensioner location is different front to rear. I dont think the front tensioner applies the same load because its location in relation to the cam gears. I reset the tension an now its remaining the same 10,000kms later. |
Paul Jeffery (Peajay)
Junior Member
Username: Peajay
Post Number: 76
Registered: 4-2002
| | Posted on Wednesday, June 25, 2003 - 2:53 pm: | |
Well it won't be over tensioning of course because how ever many times you do it you always get the same load from the spring (until the day it wears out of course) so all you are doing is keeping up with the stretch. I presume the holes are there for this reason why else would they have made the covers with this ability ? |
Hans E. Hansen (4re_gt4)
Intermediate Member
Username: 4re_gt4
Post Number: 1534
Registered: 4-2002
| | Posted on Wednesday, June 25, 2003 - 2:28 pm: | |
I've heard a few mechanics warn about over-tensioning them. It has to be a 'just right' thing, as the block 'grows' when it gets hot. If the belt ends up too tight, it can damage the internal fibers and eventually cause a failure. |
Mitchell Le (Yelcab1)
Member
Username: Yelcab1
Post Number: 562
Registered: 11-2001
| | Posted on Wednesday, June 25, 2003 - 1:36 pm: | |
Nope,
The book says, if they are loose, change them.
ML |
Paul Jeffery (Peajay)
Junior Member
Username: Peajay
Post Number: 74
Registered: 4-2002
| | Posted on Wednesday, June 25, 2003 - 12:01 pm: | |
Have you ever found them loose enough to do a re-tension ? If you have I would expect other V8 models would also need one. |
Mitchell Le (Yelcab1)
Member
Username: Yelcab1
Post Number: 561
Registered: 11-2001
| | Posted on Wednesday, June 25, 2003 - 9:46 am: | |
I do a periodic tension check before I start the car. I reach in, touch the belts, make sure there is decent tension.
But, I have a GT4 so the belts are accessible without removing a cover. |
Paul Jeffery (Peajay)
Junior Member
Username: Peajay
Post Number: 73
Registered: 4-2002
| | Posted on Wednesday, June 25, 2003 - 5:42 am: | |
I'm just finishing up my first belt change on my 328, managed to have the front bank front cam jump a tooth, so had to go back and re-align that one to the cam marks. I was wondering about a tension check after the belts had run for a while, it seems that they do stretch looking at the old ones. There is a hole in both belt covers that gives access to the tensioner pulley nut with everything installed, I presume the idea is to do a periodic re-tension by loosening the nut and allowing the spring tensioner to take up the slack (after rotating the engine a couple of times of course) Is anyone actually doing this check ?? Is it called out anywhere ? |