ATI Damper: Opti removal & Underdrive issues?
Thread Starter
Race Director
Joined: Apr 2000
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From: Texas
ATI Damper: Opti removal & Underdrive issues?
As I continue to plan my 383 build, I also want to think ahead to future maintenance activities in addition to general performance.
Two questions for those using an ATI damper on LT1/4 cars...
1) To remove & replace the Opti with the engine installed in the car....did you have to go to any extreme measures....ie pulling the engine
Did the Opti fit past the ATI hub?
2) I'm bouncing between the 7.5" and the 6.78" dampers. For those that are using the smaller damper, any issues typical of underdrive pullies?
Two questions for those using an ATI damper on LT1/4 cars...
1) To remove & replace the Opti with the engine installed in the car....did you have to go to any extreme measures....ie pulling the engine
Did the Opti fit past the ATI hub?2) I'm bouncing between the 7.5" and the 6.78" dampers. For those that are using the smaller damper, any issues typical of underdrive pullies?
Melting Slicks
Joined: Oct 2006
Posts: 2,238
Likes: 10
From: College Station TX
On my 383, I'm using the smaller, all aluminum ATI.
1) I put my opti on AFTER the damper, so it should come out without any issues.
2) I haven't had any charging or PS issues since installing it. I did have to get a shorter belt, *but* I'm running an AC delete bracket, so if you have an actual AC compressor, a shorter belt might not be needed. I ended up with a 663 belt (stock is 670).
1) I put my opti on AFTER the damper, so it should come out without any issues.
2) I haven't had any charging or PS issues since installing it. I did have to get a shorter belt, *but* I'm running an AC delete bracket, so if you have an actual AC compressor, a shorter belt might not be needed. I ended up with a 663 belt (stock is 670).
Drifting
Joined: Jan 2006
Posts: 1,740
Likes: 2
From: Winchester Virginia
As I continue to plan my 383 build, I also want to think ahead to future maintenance activities in addition to general performance.
Two questions for those using an ATI damper on LT1/4 cars...
1) To remove & replace the Opti with the engine installed in the car....did you have to go to any extreme measures....ie pulling the engine Did the Opti fit past the ATI hub?
2) I'm bouncing between the 7.5" and the 6.78" dampers. For those that are using the smaller damper, any issues typical of underdrive pullies?
Two questions for those using an ATI damper on LT1/4 cars...
1) To remove & replace the Opti with the engine installed in the car....did you have to go to any extreme measures....ie pulling the engine
Did the Opti fit past the ATI hub?2) I'm bouncing between the 7.5" and the 6.78" dampers. For those that are using the smaller damper, any issues typical of underdrive pullies?
If I EVER have to pull my 7.55" ATI pulley it will require me to jack the front end of the motor up at least 4 inches to seperate the pully from the hub on my LT4. once you get the pully off, I believe that you can get the opti off without moving the hub, but that's just what I believe based upon my install. I have not had to remove it yet but when I dropped the motor in, I had to unbolt and pull the motor back up about 6 inches to get the pulley on the hub, then I dropped the motor in and bolted it up. If I were to do it again, I would have completly installed the pulley and hub before I ever swung the motor over for the inital install and would have been done with it. I just hope that I don't have to remove it for any reason anytime soon. The ATI hub is much smaller in outside diameter than the stock LT4 hub which uses the three prongs to attach the stock hub to. Eventhough I did not pull the opti, I believe that you should be able to do so without pulling the hub, but the biggest issue will be getting the ATI hub off of the front of the motor with that lower cross member and no room to get the pulley past the nose of the hub. I wanted to keep my stock ratio's so I went with the 7.55. I hope this helps!
R/Noland
Le Mans Master
Joined: Feb 2005
Posts: 5,146
Likes: 3
From: The Motor City
I have no info to add on install regarding ltx, just an option that costs a few bucks less is Fluidamper (sfi etc.) that you may want to check out. I have one on mine, and is well made w/no issues.
http://www.fluidampr.com/CHEVROLET.htm
http://www.fluidampr.com/CHEVROLET.htm
Drifting
Joined: Jan 2006
Posts: 1,740
Likes: 2
From: Winchester Virginia
I have no info to add on install regarding ltx, just an option that costs a few bucks less is Fluidamper (sfi etc.) that you may want to check out. I have one on mine, and is well made w/no issues.
http://www.fluidampr.com/CHEVROLET.htm
http://www.fluidampr.com/CHEVROLET.htm
Jim,
One thing that most people don't realize is that the LT4 motors have one or two parts associated with them that just don't have alot of aftermarket options for, and this is one of them. The ATI, IMHO was the way that I HAD to go, because I was going to keep my reluctor ring. Even after I decided to dump my reluctor ring, the ATI was setup with a spacer kit that allowed me to go from LT4 to LT1 hub in a matter of seconds. Just bite the bullet, if your budget allows you to, and go with the ATI. I think in the long run you'll be much happier!
Just my $0.02
Le Mans Master
Joined: Feb 2005
Posts: 5,146
Likes: 3
From: The Motor City
You're probably right, I'm sure you looked at this area pretty long and hard. I am not an LT guy, and I do think the ATI stuff is a quality just pricey is all. Thought it might be worth a look see or call.
Thread Starter
Race Director
Joined: Apr 2000
Posts: 15,344
Likes: 4,009
From: Texas
I have no info to add on install regarding ltx, just an option that costs a few bucks less is Fluidamper (sfi etc.) that you may want to check out. I have one on mine, and is well made w/no issues.
http://www.fluidampr.com/CHEVROLET.htm
http://www.fluidampr.com/CHEVROLET.htm
For me it boils down to staying with the stock LT4 setup or the ATI. ATI is preferred for all the reasons cited by Noland in this thread and his 383 build thread. I'm just trying to understand what I'm getting myself into regarding maintenance...not that any of these cars ever need that
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Drifting
Joined: Jan 2006
Posts: 1,740
Likes: 2
From: Winchester Virginia
Appreciate the input. The only LTx applications they have are for f-bodies. Due to a different accessory configuration/spacing it won't work with the Vette.
For me it boils down to staying with the stock LT4 setup or the ATI. ATI is preferred for all the reasons cited by Noland in this thread and his 383 build thread. I'm just trying to understand what I'm getting myself into regarding maintenance...not that any of these cars ever need that
For me it boils down to staying with the stock LT4 setup or the ATI. ATI is preferred for all the reasons cited by Noland in this thread and his 383 build thread. I'm just trying to understand what I'm getting myself into regarding maintenance...not that any of these cars ever need that
I agree with you investigating all of your options. There is another pulley that can be used on the LT4's ONLY if you don't keep the reluctor ring, thus making it a LT1 type of hub. This damper pulley is just over $100, but the company is/was out of them and had no idea when they were going to make anymore. All of their dealers were out of stock so I had NO other choice IMO, but to fork out the big bucks and go ATI. PLEASE do yourself a favor and don't spend more than you have to on it as i did. I bought my directly from ATI which they initially wanted WAY more than Jegs or Summit for it. They KILLED Me on Shipping and Taxes. The really screwed up part is that the company isn't that far from me and I would have been more than willing to drive over and pick it up. When you go to order your pulley, check between Summit and Jegs to get the lowest price because they fluctuate. I have found that Summit will normally have the lowest and best price out there. As far as the issues over stock go, I believe that the ATI design is MUCH easier to negate around than the stock. I also know that for a high revving motor, this is the type of insurance policy that you need. Good luck in which ever way you go and keep us posted!
R/Noland
Melting Slicks
Joined: Oct 2006
Posts: 2,238
Likes: 10
From: College Station TX
While the LT4 damper is different from an 96 LT1 unit, the spacing is the same. 96-97 had the reducer ring (LT1 or LT4), while 92-95 did not. I'm really not sure how LT4 specific applies to aftermarket dampers. 
Drifting
Joined: Jan 2006
Posts: 1,740
Likes: 2
From: Winchester Virginia
The 97 LT's were not available in the Y-Bodies, only the F and B's. From ATI, there is no difference between the damper they sell for the LT1 or the LT4, same damper, and they all come with the spacers included with the pulley and hub for either application 92 - 96.
http://www.atiperformanceproducts.co...ts/damserp.htm
R/Noland
Le Mans Master
Joined: Jan 2003
Posts: 8,596
Likes: 19
From: Portland Oregon
Appreciate the input. The only LTx applications they have are for f-bodies. Due to a different accessory configuration/spacing it won't work with the Vette.
For me it boils down to staying with the stock LT4 setup or the ATI. ATI is preferred for all the reasons cited by Noland in this thread and his 383 build thread. I'm just trying to understand what I'm getting myself into regarding maintenance...not that any of these cars ever need that
For me it boils down to staying with the stock LT4 setup or the ATI. ATI is preferred for all the reasons cited by Noland in this thread and his 383 build thread. I'm just trying to understand what I'm getting myself into regarding maintenance...not that any of these cars ever need that
Burning Brakes
Joined: Nov 2004
Posts: 781
Likes: 0
I had the larger diameter ATI (used the stock belt on my '92, queer 2 sided one), steel hub/aluminum damper I believe?
I had already converted to '95 Opti, Cloyes double roller timing set, and removed the WP drive (elec. Meziere).
If I remember correctly, this ATI damper didn't have the extra 'meat' behind the pulley ribs, so I could get the Opti off/on without removing the damper. But with the '92 belt system, I had to take the bolts out of the alternator to get the belt on (just not enough swing in the tensioner for the slightly larger diameter pulley/damper). This may not be an issue on the '93L and later serpentine system.
I had to do 2 or 3 Opti swaps, so it was a Godsend! It was about the only part on my build-up that was actually worth its higher cost, both in quality and materials.
I had to have the hub honed out for my forged Scat 3.75" crank (some aftermarket crank snouts seem to be a bit larger than GM). Since it was steel, keyed, and an improved design over stock, I went with only about .0005"+ (half thousandth, plus) of press fit. Spun it past 7,000 RPM, no problem.
I had already converted to '95 Opti, Cloyes double roller timing set, and removed the WP drive (elec. Meziere).
If I remember correctly, this ATI damper didn't have the extra 'meat' behind the pulley ribs, so I could get the Opti off/on without removing the damper. But with the '92 belt system, I had to take the bolts out of the alternator to get the belt on (just not enough swing in the tensioner for the slightly larger diameter pulley/damper). This may not be an issue on the '93L and later serpentine system.
I had to do 2 or 3 Opti swaps, so it was a Godsend! It was about the only part on my build-up that was actually worth its higher cost, both in quality and materials.
I had to have the hub honed out for my forged Scat 3.75" crank (some aftermarket crank snouts seem to be a bit larger than GM). Since it was steel, keyed, and an improved design over stock, I went with only about .0005"+ (half thousandth, plus) of press fit. Spun it past 7,000 RPM, no problem.
Burning Brakes
Joined: Nov 2006
Posts: 1,102
Likes: 1
From: Portsmouth Virginia 396LT4 435RWHP/400RWTQ Best so far 11.26 @ 123mph
Jim,
Use of the 6.875 ATI super damper does allow the removal of the opti with no problem on my 95. I would think the 7.5 should clear also. I run a fabricated offset adapter on my alternator/ aluminum bracket to compensate for the smaller damper in order to run stock length belts but running a shorter belt would be better once you find the correct length needed.
Rick
Use of the 6.875 ATI super damper does allow the removal of the opti with no problem on my 95. I would think the 7.5 should clear also. I run a fabricated offset adapter on my alternator/ aluminum bracket to compensate for the smaller damper in order to run stock length belts but running a shorter belt would be better once you find the correct length needed.
Rick
Thread Starter
Race Director
Joined: Apr 2000
Posts: 15,344
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From: Texas
Jim,
Use of the 6.875 ATI super damper does allow the removal of the opti with no problem on my 95. I would think the 7.5 should clear also. I run a fabricated offset adapter on my alternator/ aluminum bracket to compensate for the smaller damper in order to run stock length belts but running a shorter belt would be better once you find the correct length needed.
Rick
Use of the 6.875 ATI super damper does allow the removal of the opti with no problem on my 95. I would think the 7.5 should clear also. I run a fabricated offset adapter on my alternator/ aluminum bracket to compensate for the smaller damper in order to run stock length belts but running a shorter belt would be better once you find the correct length needed.
Rick
Thanks guys.One last question....Is there any way to get the 6.875" damper off the hub and out of the way with the engine in the car (or the engine slightly lifted....ie jacked up an inch or two)?
Trying to think ahead to if I ever have to change the crankshaft seal in the timing chain cover, etc.
Melting Slicks
Joined: Dec 1999
Posts: 2,816
Likes: 2
From: Austin, TX
Thanks guys.One last question....Is there any way to get the 6.875" damper off the hub and out of the way with the engine in the car (or the engine slightly lifted....ie jacked up an inch or two)?
Trying to think ahead to if I ever have to change the crankshaft seal in the timing chain cover, etc.
That being said, the damper just bolts to the front of the hub but needs to slide off a little over an inch to remove it once it's unbolted. It's definitely doable, but you may need to jack up the motor a little as you're likely to hit the PS rack when you remove it.
To pull the hub, you'll definitely need to jack up the motor and probably remove the radiator and fans to get the clearance you'll need for a puller / installer.
One additional thing to check before you install your new ATI damper hub: check the ID of the hub against the OD of your crank snout. On my LT4 stock crank the fit was too tight and I had to have the hub honed slightly to allow it to press-fit properly (I broke 2 installers before I figured that out!).
Burning Brakes
Joined: Nov 2006
Posts: 1,102
Likes: 1
From: Portsmouth Virginia 396LT4 435RWHP/400RWTQ Best so far 11.26 @ 123mph
Jim,
Never tried to remove the 6.875 ATI damper in the car yet. Guess you could if engine was raised high enough.It needs to come up at least 3 1/2" to clear the ram. The trans might hit the tunnel before you get enough clearance though. You only have 1/4" or less of facial clearance installed with the steering ram and the damper face so the ram might have to be taken loose and moved forward to get the damper off as stated above. Need at least an inch. My damper has always been installed on the hub before the engine went in the car. Also as mentioned above, measuring for proper press fit of hub on the crank snout is very important. Honing could be required if doing a new hub install. You can definitely screw up a hub,crank, and/or tool if trying to install with too much press fit. Just follow ATI instructions for proper press fit.
Rick Geer
Never tried to remove the 6.875 ATI damper in the car yet. Guess you could if engine was raised high enough.It needs to come up at least 3 1/2" to clear the ram. The trans might hit the tunnel before you get enough clearance though. You only have 1/4" or less of facial clearance installed with the steering ram and the damper face so the ram might have to be taken loose and moved forward to get the damper off as stated above. Need at least an inch. My damper has always been installed on the hub before the engine went in the car. Also as mentioned above, measuring for proper press fit of hub on the crank snout is very important. Honing could be required if doing a new hub install. You can definitely screw up a hub,crank, and/or tool if trying to install with too much press fit. Just follow ATI instructions for proper press fit.
Rick Geer
Safety Car
Joined: Jul 2001
Posts: 4,871
Likes: 15
From: Detroit's West Side MI
I'm late to this party (had a National Championship race to lose last weekend) but I can't say enough how much the ATI damper helps with opti removals. I can do an optispark swap in about 2 hours now, including emptying and refilling the coolant. I also have the light aluminum damper, and that, coupled with the AL flywheel, lets my 383 spin up like a little 4 cylinder. Beautiful.
But...if you need to remove the pulley for any reason you're pulling the motor.
Burning Brakes
Joined: Nov 2004
Posts: 781
Likes: 0
I am evidently too stupid for those guys. I post a tech/engine question and don't get any replies.
Nobody wuvs me...
Besides, anytime I smell an Opti related thread, I have to jump in and give my "two cents worth".
You haven't blow-ed that 383 up yet? Are you even trying?
Yeah, that ATI hub is just too long. I don't even think you can extract the balancer if you unbolt the rack and tip it forward. Just too precise of a fit to try and tilt it, **** it, or pry it off/on, without essentially pulling the engine up off the mounts.
I guess the good news is that the front seal should last 3 or 4 times longer than your typical Opti (Optis).
Nobody wuvs me...
Besides, anytime I smell an Opti related thread, I have to jump in and give my "two cents worth".
You haven't blow-ed that 383 up yet? Are you even trying?
Yeah, that ATI hub is just too long. I don't even think you can extract the balancer if you unbolt the rack and tip it forward. Just too precise of a fit to try and tilt it, **** it, or pry it off/on, without essentially pulling the engine up off the mounts.
I guess the good news is that the front seal should last 3 or 4 times longer than your typical Opti (Optis)
.
Last edited by 500hp; Sep 17, 2008 at 09:38 PM.
