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Intermountain F3A - Will The Shell Fit on a Different Chassis?

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Intermountain F3A - Will The Shell Fit on a Different Chassis?
Posted by richhotrain on Tuesday, December 1, 2015 11:07 AM

I have complained about this before.  The Intermountain F3A runs way too slow. I have four of these locos.  I don't know for sure what the problem is, whether it is the gearing or, perhaps, the decoder. But, I suspect the gearing because I use different decoders in these locos, some factory installed and others after-market.

So, my question is, will the Intermountain shell fit another brand of chassis?

Rich

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Posted by riogrande5761 on Tuesday, December 1, 2015 3:41 PM

What he said.  Intermountain manufactured their F unit shells to fit the Stewart/KATO F chassis.  You see, the IMR F shells were out on the market well before they had a chassis/motor unit available for them, but still wanted to offer them for sale.  So for that interim, they recommended hobbyists obtain a Stewart chassis and mount their IMR shell on it.  Eventually they developed their own chassis, which by all reports has been a very good one.  Rich's comments are one of the very few I've seen that stated unhappiness with the IMR chassis.

Rio Grande.  The Action Road  - Focus 1977-1983

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Posted by richhotrain on Tuesday, December 1, 2015 4:22 PM

Excellent.  Thanks, guys, I will try the Stewart/Kato F chassis.  

Rich

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Posted by ATLANTIC CENTRAL on Tuesday, December 1, 2015 4:31 PM

Sounds like a decoder issue, because my moderately sizeable fleet of Intermountain F units all run just fine - on DC.

And as others have said, the shell works fine on the Stewart drive.

Sheldon 

    

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Posted by richhotrain on Tuesday, December 1, 2015 4:37 PM

ATLANTIC CENTRAL

Sounds like a decoder issue, because my moderately sizeable fleet of Intermountain F units all run just fine - on DC.

What sort of test equipment would I need to determine the scale speed of one of these Intermountain F3 locos?  My four IM locos run a heckuva lot slower than any other of my many passenger diesel locos.

Rich

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Posted by Heartland Division CB&Q on Tuesday, December 1, 2015 5:04 PM

Rich ... Your problem perplexes me. ... I have two Intermountain F-units which I regularly run with other makes of F-units. I don't have your situation with mine. ... Perhaps you should contact Intermountain with your question. 

 

I did install an Intermountain F7 B-unit shell on an Athearn non-powered F7 chassis. It required some cutting and filing inside the shell. 

GARRY

HEARTLAND DIVISION, CB&Q RR

EVERYWHERE LOST; WE HUSTLE OUR CABOOSE FOR YOU

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Posted by richhotrain on Tuesday, December 1, 2015 5:22 PM

Heartland Division CB&Q

Rich ... Your problem perplexes me. ... I have two Intermountain F-units which I regularly run with other makes of F-units. I don't have your situation with mine. ... Perhaps you should contact Intermountain with your question. 

I have lived with this problem for quite some time. At one time awhile back, I did call Intermountain and they claimed that the slower speed was normal as the gear ratios were set to simulate slower speed F3 locos.  Dunno, they just seem too slow for me.  

What test equipment would I need to conduct a scale speed test?

Rich

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Posted by "JaBear" on Tuesday, December 1, 2015 5:36 PM
Gidday Rich, A watch with a second hand and a tape measure.
Here’s a link to some tables that I find of use including Table 2 Scale Speeds.
 
EDIT: After a very quick look I see that EMD offered the F3 with different gear ratios, the variation in top speed from 55 to 102 mph.
 

Cheers, the Bear.Smile

"One difference between pessimists and optimists is that while pessimists are more often right, optimists have far more fun."

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Posted by richhotrain on Tuesday, December 1, 2015 6:09 PM

EDIT: After a very quick look I see that EMD offered the F3 with different gear ratios, the variation in top speed from 55 to 102 mph.

I suppose I could be content with the slower speed. OK, I will run some speed tests tomorrow.
 
Rich

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Posted by SouthPenn on Tuesday, December 1, 2015 11:12 PM

You might want to look into replacement gearsets to get the speed you want.

South Penn
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Posted by richhotrain on Wednesday, December 2, 2015 7:58 AM

I ran some speed tests and started a new thread with the results.

Rich

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Posted by fieryturbo on Thursday, December 3, 2015 12:12 PM

This would depend on the age of the engine of course, but have you cleaned out and reapplied all lube to the engine?

If this is a newer engine with few hours on it, I'd contact Intermountain for help if I were you.

Julian

Modeling Pre-WP merger UP (1974-81)

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