TDC question

supo4
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TDC question

Postby supo4 » Thu Sep 17, 2015 11:36 am

Is there a difference in key ways on the crankshaft for 4age big port in a aw11 and a 4age big port in a ae86?
I thought a big port 3 rib was a big port 3 rib regardless the car. The reason I ask is when I line my harmonic balancer up with the timing marks my piston is not at the top of its stroke and I'm wondering if the balances are keyed differently I've done some digging and I'm not having any luck. It is off about 7 degrees.
1966 mustang (my lover)
2006 f150 (my regular)
1986 gts Corolla (my affair)

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ritz
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Re: TDC question

Postby ritz » Thu Sep 17, 2015 12:26 pm

supo4 wrote:Is there a difference in key ways on the crankshaft for 4age big port in a aw11 and a 4age big port in a ae86?
I thought a big port 3 rib was a big port 3 rib regardless the car. The reason I ask is when I line my harmonic balancer up with the timing marks my piston is not at the top of its stroke and I'm wondering if the balances are keyed differently I've done some digging and I'm not having any luck. It is off about 7 degrees.



Are you using an OEM harmonic balancer? What are you using as your TDC reference mark? Your timing belt could also be off a tooth.

Aftermarket ones are known to be off.

supo4
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Re: TDC question

Postby supo4 » Thu Sep 17, 2015 3:20 pm

Oem balancer and t3 camgears
1966 mustang (my lover)
2006 f150 (my regular)
1986 gts Corolla (my affair)

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Rogue-AE95
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Re: TDC question

Postby Rogue-AE95 » Thu Sep 17, 2015 5:23 pm

ritz wrote:Aftermarket ones are known to be off.


Crank pulleys?
'88 Corolla All-Trac

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totta crolla
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Re: TDC question

Postby totta crolla » Fri Sep 18, 2015 1:51 am

The crank pulley is in 3 separate parts.
Behind the big part that drives the alternator belt is a small cog wheel that drives the timing belt. This small cogged pulley has a reference mark for TDC on it.
If that TDC mark aligns correctly but the larger crank pulley does not then it is likely that the outer ring of the crank pulley has shifted on the rubber damper that joins the two parts of the crank pulley.
http://www.pbase.com/aw11mr2/image/87973968

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gotzoom?
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Re: TDC question

Postby gotzoom? » Fri Sep 18, 2015 9:13 am

Also, verify that the woodruff key is in-tact and preventing the harmonic balancer from turning.

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Re: TDC question

Postby yoshimitsuspeed » Fri Sep 18, 2015 7:30 pm

The crank key and it's position are the same.
However different pulleys have timing marks in different locations so for example if you are using an AE86 timing cover and an AW11 pulley what looks like TDC will not be TDC.
Also be aware that transverse pulleys such as the AW11 are spaced differently than longitudinal pulleys like the AE86 so you can't mix and match them.

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Re: TDC question

Postby Rogue-AE95 » Sat Sep 19, 2015 9:19 am

yoshimitsuspeed wrote:The crank key and it's position are the same.
However different pulleys have timing marks in different locations so for example if you are using an AE86 timing cover and an AW11 pulley what looks like TDC will not be TDC.
Also be aware that transverse pulleys such as the AW11 are spaced differently than longitudinal pulleys like the AE86 so you can't mix and match them.


Interesting, I never knew this. It is aggravating that Toyota did not make all 4A parts line up the same. At least they could have let the crank pulleys and accessories all be the same. I was planning to keep my 4A-FE AC compressor & bracket and add in the 4A-GE (FWD) alternator & bracket, but I've read that the GE pulleys (alt, AC, crank) will not all line up to the FE crank pulley.

Does the AE86 crank pulley sit farther from or closer to the timing cover?
'88 Corolla All-Trac

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Re: TDC question

Postby yoshimitsuspeed » Sat Sep 19, 2015 6:25 pm

Rogue-AE95 wrote:
yoshimitsuspeed wrote:The crank key and it's position are the same.
However different pulleys have timing marks in different locations so for example if you are using an AE86 timing cover and an AW11 pulley what looks like TDC will not be TDC.
Also be aware that transverse pulleys such as the AW11 are spaced differently than longitudinal pulleys like the AE86 so you can't mix and match them.


Interesting, I never knew this. It is aggravating that Toyota did not make all 4A parts line up the same. At least they could have let the crank pulleys and accessories all be the same. I was planning to keep my 4A-FE AC compressor & bracket and add in the 4A-GE (FWD) alternator & bracket, but I've read that the GE pulleys (alt, AC, crank) will not all line up to the FE crank pulley.

Does the AE86 crank pulley sit farther from or closer to the timing cover?


Unfortunately different applications have different requirements. I believe on the AE86 they were trying to move the fan closer to the radiator so they pushed it out.
On the other hand the transverse motors are very tight between the frame rails so they moved the belts as close to the motor as possible.
On FF cars the timing marks would need to be more on the exhaust side to see them easily whereas the on the MR2 those marks are impossible to see so they moved the marks to the intake side of the motor and added a pointer there.
It's in manufacturers best interest to change as little as possible so if they did there is likely a very good reason as it would have added a ton of engineering, R@D and manufactuirng cost and time.

I don't know for sure about the FE but I wouldn't be at all surprised if it was spaced differently or had other issues with mixing and matching parts.

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