My first TB, i think I need help....
#1
Burning Brakes
Thread Starter
My first TB, i think I need help....
I think I extremely need it.
Old belt :at 0 tdc driver's Side cam gear was Perfect, passenger's side was about 1 mm retarded.
New belt : started routing it from crank gear, at drivers Side, i noticed that belt won't "sit" on the very first available gear, actually it looks i have a "gap" of half a tooth. So the belt is now on, but I have some slack between oil pump gear and camshaft gear,no slack when belt tooth is on the gear tooth.
I am tempted to turn crank and see what happened at tdc, but i am more scared to do it...
Help from me and my '92 gts.
Old belt :at 0 tdc driver's Side cam gear was Perfect, passenger's side was about 1 mm retarded.
New belt : started routing it from crank gear, at drivers Side, i noticed that belt won't "sit" on the very first available gear, actually it looks i have a "gap" of half a tooth. So the belt is now on, but I have some slack between oil pump gear and camshaft gear,no slack when belt tooth is on the gear tooth.
I am tempted to turn crank and see what happened at tdc, but i am more scared to do it...
Help from me and my '92 gts.
Last edited by siscogts; 04-03-2017 at 02:16 AM.
#2
Burning Brakes
Thread Starter
Additional info :Gates belt, heads should be virgin, never machined, cam gears bolts looked never touched for fine setup, with this slack cam gears are perfectly "matched" with no slack .i am using dwayne tutorial.
#3
Rennlist Member
It looks like the left side might be a tooth off (car's left side, right side in the picture). You want the crank locked at the "45" mark (45-deg BTDC), then string the belt around the (car's) left side, then turn the gear gently anti-clockwise with a 30mm wrench-- to pull the slack out of the belt from the crank, and around the oil pump to the (car's) left-side gear. Check the mark, then clamp it here with a small clamp. You want no slack from crank, past oil pump to the (car's) left-side gear.
Then route the belt around the WP and onto the right-side gear last.
Then route the belt around the WP and onto the right-side gear last.
#5
Rennlist Member
When the belt is fully assembled and in operable condition with the belt tensioned is when you should not move the engine anti-clockwise. I also recommend you stick with the convention of using the terms "driver side" and "passenger side" when referring the cam banks.
Moving the individual cams anti clockwise for cam timing alignment purposes is no problem. You have correctly put an index mark on the tooth that aligns to the notch in the casing when at 45 BTDC. The cams can and do slip due to pressure caused by valve springs- this is more likely to happen on the passenger side- if it does it is no big deal- you move the cam to realign correctly. As Jim says turn the cams use a 30mm wrench over the big washer- do not turn the cams using the smaller fastener bolt. I like using the PK bumpstick to do this - presumably you do not have this tool?
When feeding the belt I use the bumpstick on the driver side 30mm flange to pull the belt tight between the crank sprocket, the oil pump sprocket and the driver side cam sprocket [the tensioner must be fully slack]. From this position you then feed the belt onto the passenger side cam sprocket.
With a new belt things are a bit tighter because the belt has not been through initial stretch. You will find it a bit easier if you can get a friend to hold the 30mm wrench on the driver side cam to keep the first section of belt in tension leaving you with both hands free to manipulate the belt into position. Nonetheless I did this by myself but it is a bit tricky - especially first time out.
Rgds
Fred
Moving the individual cams anti clockwise for cam timing alignment purposes is no problem. You have correctly put an index mark on the tooth that aligns to the notch in the casing when at 45 BTDC. The cams can and do slip due to pressure caused by valve springs- this is more likely to happen on the passenger side- if it does it is no big deal- you move the cam to realign correctly. As Jim says turn the cams use a 30mm wrench over the big washer- do not turn the cams using the smaller fastener bolt. I like using the PK bumpstick to do this - presumably you do not have this tool?
When feeding the belt I use the bumpstick on the driver side 30mm flange to pull the belt tight between the crank sprocket, the oil pump sprocket and the driver side cam sprocket [the tensioner must be fully slack]. From this position you then feed the belt onto the passenger side cam sprocket.
With a new belt things are a bit tighter because the belt has not been through initial stretch. You will find it a bit easier if you can get a friend to hold the 30mm wrench on the driver side cam to keep the first section of belt in tension leaving you with both hands free to manipulate the belt into position. Nonetheless I did this by myself but it is a bit tricky - especially first time out.
Rgds
Fred
#6
Burning Brakes
Thread Starter
So general consensus is: I can turn anti-clockwise a little until I have no slack.
I have no slack between cam gears anc it is a perfect fit, so I think I have to move anticlockwise the passenger side gear also, right?
is it a safe method?
Is it not best to do a turn clockwise?
Sorry for these billion questions.....
and Thanks a lot.
Francesco
PS: I rebuilt a zf auto transmission myself and was not so scary, I rebuilt manual trannys, differentials, but this first timing belt is a bit of mind****....
I have no slack between cam gears anc it is a perfect fit, so I think I have to move anticlockwise the passenger side gear also, right?
is it a safe method?
Is it not best to do a turn clockwise?
Sorry for these billion questions.....
and Thanks a lot.
Francesco
PS: I rebuilt a zf auto transmission myself and was not so scary, I rebuilt manual trannys, differentials, but this first timing belt is a bit of mind****....
#7
Rennlist Member
I would sugggest that you put a 30mm wrench on the big washer of the driver side sprocket, put tension in the anti clockwise direction until the slack in the belt between the oil pump and the driver side sprocket is taken up and then take a photo of the blue index mark relative to the notch on the back cover- when you take the photo take it from a position perpendicular to the notch so that we can see clearly where the mark sits and then post the photo. Do the same for the passenger side.
I assume that at the moment the belt is not tensioned at all.
I assume that at the moment the belt is not tensioned at all.
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#9
Rennlist Member
My concern at the moment is whether you are 1 tooth out on the driver's side sprocket. Your photo is at an angle relative to the index marks, as viewed on the first photo it seems the blue mark is retarded a bit relative ot the index mark and you have slack in the belt.
Puting some anto clockwise tension on the sprocket simulates what will happen if you tighten the belt and as the crank is locked the cams will retard slightly as tension increases.
On the other hand you can also tighten the belt now and see where the index marks sit but note that the tension will not be correct until adjusted at TDC with No1 cylinder on the firing stroke. In any event you should put some tension in the belt before releasing the crank locking tool and moving the assembly.
If one or both of the sprockets are a tooth out take the belt off and start over again before releasing the crank lock. Others have reported that even if the sprocket is one tooth out you can rotate the crank and no damage will be caused however I would not do that before I was sure the sprockets are indexed correctly relative to the crank.
If when under tension the timing marks are correct you can move the crank to TDC No1 cylinder, set the belt tension correctly, rotate the crank 2 revolutions, check tension again and if good you are home and dry.
Puting some anto clockwise tension on the sprocket simulates what will happen if you tighten the belt and as the crank is locked the cams will retard slightly as tension increases.
On the other hand you can also tighten the belt now and see where the index marks sit but note that the tension will not be correct until adjusted at TDC with No1 cylinder on the firing stroke. In any event you should put some tension in the belt before releasing the crank locking tool and moving the assembly.
If one or both of the sprockets are a tooth out take the belt off and start over again before releasing the crank lock. Others have reported that even if the sprocket is one tooth out you can rotate the crank and no damage will be caused however I would not do that before I was sure the sprockets are indexed correctly relative to the crank.
If when under tension the timing marks are correct you can move the crank to TDC No1 cylinder, set the belt tension correctly, rotate the crank 2 revolutions, check tension again and if good you are home and dry.
#10
Burning Brakes
Thread Starter
blue marks are really alligned, sorry for my angled picture. at the moment the correct position should be with TB tooth edge exactly in the middle of cam gear tooth. If I used correctly my gauge , belt tooth is 5,2mm large , 3,4 mm deep. at the moment the belt/sprocket is 5,2 mm out ....see picture...
Last edited by siscogts; 04-03-2017 at 11:32 AM.
#11
Rennlist Member
Either there is a problem with communication here or you did not grasp what I am trying to advise you to do. Appreciate you are native Italian and your English is a credit to you compared to my Italian which [very sad to say] is virtually non existent. Nonetheless lets persevere with simple steps in the hope that something will click.
1. The belt tooth that you have marked in blue should sit so that its centreline is aligned to the notch in the back cover- agreed?
2. Your photo suggests that the blue line is not aligned to the notch and in your last post you appear to say it is out by the width of one tooth- agreed?
3. When the belt is tensioned correctly the cam wheel will rotate a bit more in the anti clockwise direction - agreed?
4. When point 3 above happens it is likely that the blue mark will be out by one complete tooth pitch- agreed?
If you put some anti clockwise pressure on the cam as advised, take up the slack on the belt and take a picture perendicular to the notch it will help.
Please consider the above points and advise for each one if you understand, agree or disagree.
1. The belt tooth that you have marked in blue should sit so that its centreline is aligned to the notch in the back cover- agreed?
2. Your photo suggests that the blue line is not aligned to the notch and in your last post you appear to say it is out by the width of one tooth- agreed?
3. When the belt is tensioned correctly the cam wheel will rotate a bit more in the anti clockwise direction - agreed?
4. When point 3 above happens it is likely that the blue mark will be out by one complete tooth pitch- agreed?
If you put some anti clockwise pressure on the cam as advised, take up the slack on the belt and take a picture perendicular to the notch it will help.
Please consider the above points and advise for each one if you understand, agree or disagree.
#12
Burning Brakes
Thread Starter
1 yes, agreed.
2my camera is not alligned to camshaft marks,sorry.... yep it is one tooth out of spec , pitch of timing belt is right on the camshaft sprocket pitch.
3 yes I can rotate anticlockwise
4 yes agreed.it looks like it is advanced....
I am more scared than anything else.Ithink.
2my camera is not alligned to camshaft marks,sorry.... yep it is one tooth out of spec , pitch of timing belt is right on the camshaft sprocket pitch.
3 yes I can rotate anticlockwise
4 yes agreed.it looks like it is advanced....
I am more scared than anything else.Ithink.
#13
Rennlist Member
[QUOTE=siscogts;14083081
I am more scared than anything else.Ithink.[/QUOTE]
Far better to be "scared" than foolish! You were smart enough to feel that something was wrong and ask for advice- that is wise!
If you are now sure that you are 1 tooth out just remove the belt and start again- it is no drama. Before you mount the belt just make sure the marks are aligned- practice makes perfect.
I believe you have to be about 3 teeth out before valves start to clatter pistons.
Do post some more pics when you think you have it sorted.
Rgds
Fred
I am more scared than anything else.Ithink.[/QUOTE]
Far better to be "scared" than foolish! You were smart enough to feel that something was wrong and ask for advice- that is wise!
If you are now sure that you are 1 tooth out just remove the belt and start again- it is no drama. Before you mount the belt just make sure the marks are aligned- practice makes perfect.
I believe you have to be about 3 teeth out before valves start to clatter pistons.
Do post some more pics when you think you have it sorted.
Rgds
Fred
#14
Team Owner
It would be really smart for you to have a helper to hold the 5-8 cam and belt tight,
while you turn the 1-4 cam pulley to string the belt.
NOTE do not attempt to turn the cams with the 17 MM bolt ,
use the 30 MM washer that the bolt is holding.
then have another helper take pictures while your working the 1-4 cam.
NOTE once the crank is locked at 45BTDC then the belt slack will be removed at the 5-8 cam then onto the 1-4 cam.
Once the belt is strung then tighten the tensioner to remove any belt slack,
remove the crank lock ,
and turn the crank to TDC all of the pointers should be close.
I hope you have a Porken 32Valver tool to time your cams or atleast to check where the cam timing is
while you turn the 1-4 cam pulley to string the belt.
NOTE do not attempt to turn the cams with the 17 MM bolt ,
use the 30 MM washer that the bolt is holding.
then have another helper take pictures while your working the 1-4 cam.
NOTE once the crank is locked at 45BTDC then the belt slack will be removed at the 5-8 cam then onto the 1-4 cam.
Once the belt is strung then tighten the tensioner to remove any belt slack,
remove the crank lock ,
and turn the crank to TDC all of the pointers should be close.
I hope you have a Porken 32Valver tool to time your cams or atleast to check where the cam timing is
#15
Burning Brakes
Thread Starter