Liftmaster MODEL 480LM RJO 3800 Alternate Mounting/Extension Kit
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The LiftMaster model 480LM Alternate Mounting/Extension Kit, available is designed exclusively for use with residential Jackshaft openers including the LiftMaster 3900, 3800 and 8500 models. The extension kit is available from North Shore Commercial Door and allows the opener to be lowered on the wall. The operator may need to be lowered due to obstructions, low ceilings and other installation difficulties. A t-bracket is included to raise the operator away from the wall to accommodate the kit pieces. The Alternate Mounting/Extension Kit does not increase operation noise.
The LiftMaster 480LM extension kit comes with easy and quick installation instructions. The 480LM alternate assembly allows the garage door operator to be lowered a total of 5.9 inches from the top of the garage door. The kit contains everything needed to set up the extension unit, including a chain, a t-bracket, a 1-1/4-inch sprocket with collar and screws, a 1-inch sprocket with collar and screws and a cover assembly.
- Exclusively for use with Residential Jackshaft Opener models 3900, 3800 and 8500 models
- Enables the opener to be lowered 5.9 inches
- Quick installation
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COMMENT: Needed to mount Liftmaster 8500 above garage door due to lack of room between doors. by Robert K 6/22/2017
COMMENT: its all i could find to fit my needs by Marcus B 3/16/2016
QUESTION: I have a pole barn with 16x16 steel not insulated doors can this product work on this door? by Rick M 12/25/2015
STAFF ANSWER: Please give us a call at 800-783-6112 Ext 18 by Taylor M a
QUESTION: I have 2 3/4" clearance from the ceiling to the center of the jack shaft.<br />The jack shaft extend horizonaly 1 7/8" beyond the mounting bracket of the door track.<br />Will there be enough room from the ceiling to mount this, and it the 1 7/8" extending out enough to attach this part?<br />Thank you by Mark D 10/17/2014
QUESTION: How many Teeth are there in the sprocket? and the size of the pitch or the chain? by Bob B 4/1/2014
ANSWER: Sorry yo say the extension is installed in a rather precarious place so i can get up there to see the teeth but it works very well. by dan f a
QUESTION: The torsion bar extends only 1/2 inch beyond a plate that is part of the door track mounting hardware. So if I mount the 1" sprocket on the very end of the torsion bar, the chain will be exactly 1/2" of clearance from the mounting door track mounting hardware obstruction. Is this enough clearance for the extension kit housing? What is the total thickness of the extension kit housing? by Anthony C 1/25/2014
ANSWER: The housing is 7/8" and the sprocketas you mentioned is 1", but the sprocket inside the housing totals 1 1/4". I am not positive if your clearance would work out, but the torsion bar length of 1/2" might be a concern. I don't know if that short of a projection will provide acceptable grip to the sprocket collar.<br /><br />My application did not work out exactly as the extension kit was intended, but I got it because the sprockets would be valuable even though I had to construct something more complex. I haven't even finished, but I will state the parts are all excellent quality. by R A a
REPLY: The protrusion on the track that I need to clear is the est. 1/8 edge of an angle iron support piece that is horizontal. So that edge will only interfere with available space at about the horizontal center line of the housing. Added width of the extension assembly at either the upper or the lower sprocket will have several inches of clearance.<br /><br />It may be that the bigger issue is the amount of grip that you mention. In arriving at the 1/2" I assumed that the entire collar of the sprocket that attaches to the torsion bar would be on but at the very end of the torsion bar but that the sprocket itself would be just beyond the end of the torsion bar. My thought is that the sprocket is either welded or bolted to the collar but does not, itself provide any grip on the torsion bar. Any thoughts? by Anthony C r
REPLY: The sprocket and collar are one piece machined to the final shape, one half of the collar is separate of course so it can be tightened. I think your approach with only ½” of grip area is adequate as far as getting actual grip, the movable collar piece is not much wider that that anyway. The reason I was a little concerned is that when all of the clamping and turning forces are on a small area that does not have the support of any additional length of torsion bar on one side it might cause deforming of the bartube really which then loosens the grip. Something like the rounded off head of a bolt that happens when the wrench is not engaged with the full height of the bolt head.<br /><br /> <br /><br />If the torsion tube is thick enough material it would be fine, or if it is a little thin a plug or tight fitting chunk of smaller tube inside the last 1/2” of the main tube might help support the walls of the tube in the clamping area.<br /><br /> <br /><br />RSS by R A r
REPLY: Thank you. I am sure I can make the installation work. Step 1: I will buy the wall mount unit and the offset kit. Step 2: Test fit to see how close the collar is to the end of the torsion bar tube. Step 3: If the "grip" looks sufficient, determine if the torsion tube is 'beefy' enough so as to not crush and if in doubt, plug the tube to prevent crushing. Step 4: If still in doubt block and loosen the torsion spring and pulleys and shift the torsion bar in the direction of the opener another 1/2" or so depending on available length.<br /><br />Thank you for all of your help. by Anthony C r
REPLY: Your welcome, good luck. by R A r
ANSWER: The extension kit housing is a little over 3/4" thick. I have installed the alternate mounting kit without the housing without any problem, but this will have to be a judgement call on your end. If you need more torsion shaft, you will have to block your torsion spring, loosen the cable drums, and slide the shaft over a little to the side you are mounting the jackshaft opener on. If you don't have any experience with torsion springs, I recommend hiring a garage door professional to move the torsion shaft for you. Then, you can install the jackshaft opener which can easily be done by a DIY homeowner. Always remember that the jackshaft opener can be mounted to the right or left side of the garage door. You have to flip the cable tension monitor arm if you are going to mount it on the right side. Hope this helps! by Pace L a
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