LifeLike GP 18 and GP 20

Do these two share the same mechanism or is the truck spacing different?

 

OT: This mechanism is also correct frame length and truck spacing for GP7, GP9, GP30, GP35, and close to the F3/7/9. It is interesting that it can be used for so many kitbashes.

Please do make correction if I am wrong here.

 

The truck spacing has always been the same, but as Rick noted, the chassis have changed over the years. On the current offerings they are the same. But I have done a lot of bashing of early GP's and the Atlas GP7/9 chassis and shells and the LL/Walthers GP18 and 20 chassis and shells are mostly interchangable regardless of vintage.

 

GP7, 9, 18, 20 truck spacing is 31ft

GP28,30,35 and GP40X (GP40 prototype) its 32ft... the rear truck is kicked rearward a foot. They share the same frame length as the earlier GPs, but for a model mechanism length and frame lengths can be completely different

 

There's definitely a big difference in chassis between the the GP20 and down, and 30 and up chassis. The truck spacing is close, but an Atlas GP9 chassis will slide back and forth about 3/8 of an inch under the shell of a GP30, and there's no hope of slipping a GP9 shell onto a GP30 chassis.

 

There is a minor difference in the chassis design due to the fuel tanks being different, though this may have been combined into a universal chassis for the latest releases.
I have tried to place a later run GP18 tank onto a 2nd run GP20 chassis without success. Same applies to the Atlas GP7/9 tank on the GP20 chassis.

Otherwise, as already pointed out, the wheelbase is identical.

 

My two cents- find a late- or last-generation WalthersLifelike Proto2000 GP-18. BEST 4-axle loco Lifelike ever put out. Those GP-38's look pretty sharp too, but I heard the paint application is heavy? You can get a LL GP-20 for $30 on Ebay and the first-generation models are arguably better than the updated GP20's. DCC is an option on all but the first-gen plastic frame GP18's, go to TCS for your decoders. You won't regret it- heck, it's like buing an Atlas for 60 cents on the dollar!

 

I am going through a repowering of older Life-Like GP18's and Alco's and I'm finding some other phases of parts usage by Life-Like.

Thanks for the warning on the GP20 to GP18 fuel tank transfers - I guess I'll have to modify both tanks and/or chassis for these, whether I decide to use Atlas GP fuel tanks or Life-Like late GP18 fuel tanks on the newr GP20's, provided that the new ones I ordered are the newer everything!.

I have found numerous differences in both Life-Like GP20, GP18, Alco FA/FB, and Alco Proto RS2 Truck assemblies: a mid-phase, split frame GP18/20 with either the open gearbox, mid-phase truck w/ larger wheel diameter and taller flanges, or the newer more correct wheel diameter w/ lower profile flanges. I have seen the same with the LL Alco F's larger flanges compared to the LL RS2's w/ low profile flanges. It appears that truck and or wheel replacement with the newer wheels on some of these are possible. This would hopefully make it possible to run Life-Like powered GP18's/20's and Alco F's on code 40 rail! I'll also see if wheel replacement will fit on the LL E units as well. Just tried it - Nope! Won't work! The gears on the LL E8's are different.

I'm going through these repowerings through th next few weeks and I'll post the outcome here. The only problem I'm having is getting Life-Like parts without having to cannibalize my good Life-Like stuff!

 

Here's an Atlas GP7 shell on a late run LL GP18 chassis. It's a good fit, but not tight.

 

I have a split frame GP18 which has Atlas GP trucks under it. It is a straight swap for the LL trucks and runs smoother now, and fixed the slightly larger flange issue bumping the spike heads on Atlas C55.

 

Atlas n scale trucks under Life-Like mechanisms...

Hey - thanks Gary! I was contacting Walthers today to see if any newer Life-like GP18/20 loco wheelsets w/ low profile flanges were available, but it sounds like the Atlas trucks are worth the investment for the quality! Do you think the Atlas Alco trucks would fit the Life-Like split-frame GP18/20 mechanism as well? I'm building a Mopac chop-nose GP18 w/ Alco trucks.

Also, do you think Atlas Alco trucks will fit the Life-Like FA1/FB1 mechanisms as well?

Thanks again!:thumbs_up:
Pete

 

Pete, the issue will be the length of the ALCo sideframes and if they will hit the GP18 steps, though Atlas has released GP's with ALCo sideframes in the past (Soo GP35 722 is one).
They will be a slip fit as well.

As for the FA's, I couldn't say without pulling mine out and having a look. If they use the same bolster arrangement as the GP18 then the truck swap should work as well.

 

Sorry, I can't comment on the Alco trucks, but I know that you can't swap FM trucks between Atlas and LL/walthers. As Gats pointed out, the bolsters are different lengths. You could MAKE them fit by cutting the slots in the frame of the LL that the trucks snap into lower, but I was trying to save a few pennies ( the Atlas trucks were $4 cheaper than the LL) and decided it wasn't worth it for $8.

 

Are the atlas GP30/GP35 trucks the same as the Atlas GP7's/9's? Also, do you think the Atlas VO1000 truck would fit under a Life-Like SW9?

I just saw a Kato/ Atlas Motor - 420000 Variation for sale - would this motor work as a replacement for a Life-Like motor as well?

Anyone here know where to find a Life-Like GP18 shell? I've got a few spare GP20 shells to spare if anyone has a GP18 shell they would like to trade.

Thanks again!
Pete

 

I have several GP18 shells, the mechanisms of which I used for Atlas shells, but they are all minus d/b's. If your GP20 has d/b's, you could use the piece for the GP18.

 

Those would work - I'm modeling mopac GP18 chop-noses, and I have the low nose GP20's, I just don't have the GP18's without dynamic brakes. Let me know if you're interested in selling or trading!

Thanks!
Pete

 

Different part numbers though very similar. The GP7/9 (China) has the same truck part number as the GP38/38-2, though.

Good question. I don't know as I haven't a VO-1000 to pull apart. Anyone?

 

Hey gats -I just compared the two side by side. They won't for two reasons. The VO trucks are too long and the VO bolster is off center (the SW Life-Like is a centered bolster). Looks like a Walthers late run, low profile loco wheel set may be the only solution to run Life-Like SW's on code 55.

 

Pete, have you tried fitting the wheelsets only into the LL trucks? I'm not certain if the axle gear is the same diameter in each, or whether the stub axles of the wheels are the same diameter.
It may be as simple as changing the wheelset complete, or placing the Atlas wheels on the LL gear, rather than doing the complete truck.

Edit - incremental information.

I just tried combinations of Atlas and LL parts. The Atlas wheelsets (p/n 480304) will go into the LL SW trucks without binding. The only issue is the position of the gear in relation to the idler in the gearbox being approximately 1/2-3/4 gear width out - the Atlas gear is further outwards than the LL gear on the axle. This can be adjusted to mesh better by adjusting gauge on the side the gear is closest to and having the other side flush with the wheel back, so I don't expect there being any long term issues once done.

The Atlas wheel itself is a loose slip fit into the LL axle gear due to the LL wheel stub axle having a knurled section. ACC should assist here but check for any misalignment causing wheel wobble before doing so.
Conversely, the LL wheel stub axle will not easily go into the Atlas gear.

Additional information - the wheel diameter for Atlas is 6.56mm and LL 6.8mm, making the loco about 4% slower with the Atlas wheelsets.