Why are my balance shafts misaligned after setting them correctly?

[fiily]

Motor was set at TDC before installing belt, I verified it via bellhousing and camshaft notch. Top/Bottom balance shafts lined up perfectly at each respective notch before starting also.

I installed the balance shaft belt, lined up everything tighten the belt to 180 degree turn with fingers, started the car, let it run for 1-2 minutes, put motor at TDC again, rechecked belts and the top balance shaft is aligned with notch, bottom is off by 1.5 teeth...why??

YouTube Video Below:

https://youtu.be/fAnUYVqZE5s

[edredas]

Scroll down to the second post and give that a try. I hope it helps!

924Board.org :: View topic - How to set the timing and balance shaft belts on a 924S/944

[Rasta Monsta]

Because you didn't set them correctly?

[Bradical]

It's common, as you tighten the belt will stretch a bit. What looks like dead on with a floppy belt can be a few teeth off under proper tension. Correct and move on. There is no greater force at play here.

[fiily]

Originally Posted by Bradical

It's common, as you tighten the belt will stretch a bit. What looks like dead on with a floppy belt can be a few teeth off under proper tension. Correct and move on. There is no greater force at play here.

New Belt, all lined up before starting the engine, after starting the car and letting run, setting engine to TDC the bottom balance sprocket was off 1.5 teeth.

Do you think I had slack in the belt and that is why this happened?

[fiily]

Originally Posted by Rasta Monsta

Because you didn't set them correctly?

Shoot me Rasta

[Rasta Monsta]

Originally Posted by fiily

Shoot me Rasta

Have you seen the cost of ammo lately?

[fiily]

Ya! Too much. A beating and flogging would be better.


Either way, I redid the Balance belt again yesterday afternoon, and the same freaking results!!!!!!!!!!!!

I must have slack on the belt which jumps teeth on the lower balance shaft sprokcket, causing it to get off time with the engine.

Gonna grab the wife/kids to hold the top balance belt sprocket while I run the belt down the crank, lower bs and tensioner to prevent this.

We'll see, if it doesn't work, I will be offloading some ammo into the block.

[nynor]

do you have a contitech balance shaft belt?

[fiily]

Yes, I bought the contitech timing belt kit which includes both belts, rollers, tensioners. Please tell me you figured out my problem nynor.

CRP Industries TB107-293K2 Timing Belt Kit

For sheets and giggles, I ran the car for 25minutes without the balance belt, ran smooth as butter.

I had the car up on jacks about 35deg, and thought I needed to bleed the system, but my stant pressure tester worked by bleeding the coolant system, the car stayed at the 1st white line and the cooling fans came on. I had the fan on 0 and the heat cranked to hades hot.

This balance belt malarkey is the only thing stopping me from finally driving the car since last summer!! HELP!!!

[edredas]

If you install the belt with the marks lined up, the slack when tensioned will pull them out of alignment. This isn't any different than doing a twin cam car with two cam gears. The sprockets need to be retarded before the belt is put on, then aligned.

[nynor]

well, let's just say i had the exact same issue using a conti balance shaft belt. if you look at the teeth, they have a cutout. if you look at the teeth with the belt around one of the balance shaft pulleys, you'll also see that there is some slop. after four goes, i decided i just didn't trust the belt and bought a gates. i had forgotten that i had a conti in there. low and behold the teeth on the gates are round and fit the pulley like a glove. problem solved.

if you do a search of my recent posts on this forum, you'll see where i discuss my problem a little bit.

then i looked on the wall in my garage, where i lovingly place all the belts i change on hooks for later use as rubber protectors for vice grips and such. low and behold there were two or three balance shaft belts still hanging there. all of them with round teeth.

one more thing, i had also purchased and installed the entire kit. so i am not sure if the belt sold separately is different.

[fiily]

Originally Posted by edredas

If you install the belt with the marks lined up, the slack when tensioned will pull them out of alignment. This isn't any different than doing a twin cam car with two cam gears. The sprockets need to be retarded before the belt is put on, then aligned.

I actually took a video of the balance belt tensioned to spec 180 deg twist, with everything lined up, TDC on bellhousing, cam, and both upper and lower balance shafts on their resepctive notches, and I did this all to Clarks-Gaage specs which I would think 90% of us would use as a reference guide.


Started the car, let it run again for 2-3 minutes, put the engine to TDC, verified TDC via bellhousing and cam again, and the top balance shaft was right on the notch, the bottom was off by 1.5 teeth.

So, with everyhting tensioned, and lined up, everything should "stay" lined up at tdc, but obviously it's not happening.

[nynor]

with the conti belt, i actually over tensioned it a bit, the fourth go, and it still jumped teeth. except i actually ran my car, between tensionings, on the road and it was going 180 degrees out of phase. good luck.

[edredas]

Originally Posted by fiily

I did this all to Clarks-Gaage specs which I would think 90% of us would use as a reference guide.

Yes, and every time someone brings me their car they did themselves, the shafts are always off like you are describing. If this was a twin cam car, you would have smashed valves. Most books are written under the assumption they are being read by service techs and removing slack from a belt is understood.

In the link, I described how to move the slack to the tensioner. If all the slack is not at the tensioner then the belt will pull the shaft out of time when you start the car. The way I described is how service techs do belts on all cars to get the marks to line up with the belt on. They don't have time to spend days doing a job or replace a head when they get the marks wrong.

[fiily]

Originally Posted by edredas

Yes, and every time someone brings me their car they did themselves, the shafts are always off like you are describing. If this was a twin cam car, you would have smashed valves. Most books are written under the assumption they are being read by service techs and removing slack from a belt is understood.

In the link, I described how to move the slack to the tensioner. If all the slack is not at the tensioner then the belt will pull the shaft out of time when you start the car. The way I described is how service techs do belts on all cars to get the marks to line up with the belt on. They don't have time to spend days doing a job or replace a head when they get the marks wrong.

Ok, I will retard the balance shaft sprockets/crank out 10 deg/1.5 teeth as mentioned in that thread and , follow those instructions with routing the belt and having the slack down at the tensioner and tighten it there which should pull the cam/crank/both balance shaft marks on time then when done right and report my situation then.

Thanks Ed.

[nynor]

first off, he wouldn't have smashed valves, as we are talking the balance shafts. second, if he followed the instructions on clarks, he would have rotated the engine twice back to TDC and it would have taken the slack out for a second reading.

again, the conti belt sucks. YMMV.

[edredas]

Nynor, this is the same principle tech use to install belts on all cars. I'm being rhetorical, but if he was working a twin cam car he would have this same exact issue which would result in smashed cams.

[fiily]

Originally Posted by nynor

first off, he wouldn't have smashed valves, as we are talking the balance shafts. second, if he followed the instructions on clarks, he would have rotated the engine twice back to TDC and it would have taken the slack out for a second reading.

again, the conti belt sucks. YMMV.

If you click on my video in the 1st link I see what nynor is saying, the cogs are squared on every pulley the bb touches, and the conti nubs are rounded.

I have turned the engine over by the crank after setting the belt tension, and retensioned then and still it happened, we will see if the way ed mentioned in the thread resolves it.

[nynor]

your belt is exactly as i described. there is a notch at the end of each tooth and the teeth are more triangular than round. i am done here. good luck.