RW613 Superliner rear crossmember

[Vladislav]

15 hours ago, BottleHauler84 said:

@FarnorthMN I was looking at my 1988 MH613 with Neway air ride. It has this style rear cross member on it which is also a very popular crossmember Mack used for rear,  mid and at the cab. The part number is 9QL4551M. Mine has 2 of those back to back. They are 1/2" thick steel. 

You can find these used pretty easy. PG Adams also make these exact crossmembers and the quote i got from them was $257.05 a piece. 

 

Here's a couple internet pics of the 9QL4551M crossmember 

Worth to point out these do exist of different width. I have two R-models (which are originally differerent to a RW/MH) with those and the truck with double frame has them shorter than the single rail unit.

BTW my R-model with Neway has particulary this style for the rearmost crossmember. With shock brackets attached to it. 

[FarnorthMN]

fantastic thanks @Vladislav I'll keep at it it ill find it. Just takes time. 🤣🤣

[FarnorthMN]

19 hours ago, BottleHauler84 said:

Between Goodys Truck parts in toledo  and browsing LQK, Heavy Truck Parts and Ebay i usually find alot of stuff im looking for.

Being you're up in Minnesota, Vanderhags is one place to look. I know awhile back they had an early 90s MH cabover they parted out. Not sure if there's anything left but they have several yards.  Also, C&H Truck Parts in Nebraska i know for a fact has some MH Ultraliner and possibly a RW Superliner out there. 

https://candhtruck.com/

The Superliner2 and Ultraliner of the mid-late 80s share the same frames, so a MH Ultraliner crossmember will work on your RW Superliner.

Checked with vander haags today they didn't have any RW or MH in the lot.  Also call C&H they are in the process of looking.  I will lightly brush the whole  rear cross see if I can find a part number tomorrow! 

[kscarbel2]

On 11/18/2025 at 6:55 PM, FarnorthMN said:

Looking for rear suspension crossmember for my 1986 superliner.  its for the rear shocks on NeWay air suspension.

let me know what you have. thanks! 

Single channel frame?

9QL4551M x 2

44RU11192 spacer plate x 2

[FarnorthMN]

2 hours ago, kscarbel2 said:

Single channel frame?

9QL4551M x 2

44RU11192 spacer plate x 2

yes sir single frame! this is great thanks that will help thing along for sure!   

[FarnorthMN]

8 hours ago, Vladislav said:

Worth to point out these do exist of different width. I have two R-models (which are originally differerent to a RW/MH) with those and the truck with double frame has them shorter than the single rail unit.

BTW my R-model with Neway has particulary this style for the rearmost crossmember. With shock brackets attached to it. 

so are the 9QL4551M  replament for the style I have? that will work for the new way suspension mounts? Just need to drill? sorry for my stupidness 

[BottleHauler84]

On 11/20/2025 at 10:37 PM, FarnorthMN said:

so are the 9QL4551M  replament for the style I have? that will work for the new way suspension mounts? Just need to drill? 

My 88 MH with Neway has the 9QL4551M2 with spacers crossmembers for the rearmost crossmember with the shock mount brackets bolted on it. You may have to punch new holes use them. Im not sure if the bolt pattern is the same as your current crossmember. 

Here's a document showing the different style crossmember Mack used. 

[BottleHauler84]

FYI, I checked all my torque rods on my truck with Neway.....im not sure what your axle spacing is on yours, so could be different but id say side to side rods are the same no matter.

I had 17QF460P245 for the front to back rods, and 17QF464p183 for side to side rods.

Atro came up with these rods as replacements. I thought they were pretty reasonable. 

TR62-41245  24.50" inches long

TR62-41183 18.25" inches long

 

[kscarbel2]

17 hours ago, FarnorthMN said:

so are the 9QL4551M  replament for the style I have? that will work for the new way suspension mounts? Just need to drill? sorry for my stupidness 

Plate type replacement. Used in pairs back-to-back. Sometimes a single one at the rear of an R-model (A DM would use 9QL4551M8's and then an I-beam crossmember at the rear).

[FarnorthMN]

2 minutes ago, kscarbel2 said:

Plate type replacement. Used in pairs back-to-back. Sometimes a single one at the rear of an R-model (A DM would use 9QL4551M8's and then an I-beam crossmember at the rear).

I did find a used 9QL4551M back to back im going to get some mesurments and might go that route.  the back to back seems like its a way stronger option then what I have now witch is pretty much stamped steel.  

[FarnorthMN]

11 hours ago, BottleHauler84 said:

FYI, I checked all my torque rods on my truck with Neway.....im not sure what your axle spacing is on yours, so could be different but id say side to side rods are the same no matter.

I had 17QF460P245 for the front to back rods, and 17QF464p183 for side to side rods.

Atro came up with these rods as replacements. I thought they were pretty reasonable. 

TR62-41245  24.50" inches long

TR62-41183 18.25" inches long

 

Ok thats great, I'll mesure them tonight and if they mesure out ok I'll just order them.  They have got to be done at some point anyway.  I will also go to atro and just double check bushing measurements! 

[kscarbel2]

On 11/21/2025 at 3:47 PM, FarnorthMN said:

I did find a used 9QL4551M back to back im going to get some mesurments and might go that route.  the back to back seems like its a way stronger option then what I have now witch is pretty much stamped steel.  

Correct.

[Vladislav]

On 11/21/2025 at 6:37 AM, FarnorthMN said:

so are the 9QL4551M  replament for the style I have? that will work for the new way suspension mounts? Just need to drill? sorry for my stupidness 

Looks like Mack used different styles of the crossmembers which played their role equally. Some trucks had the style your truck have, some those flat style doubles. That's for 80's years and maybe earlier. Don't know the reason. Options? Or just supplys from different vendors? My R's are Canadian built (actually assembled) and they look slightly different in a few points than typical US production vehicles. Of what I noted (if I'm not wrong) a certan chassis has all the crossmembers of the same style (what makes sence). But practically it doesn't look any wrong if you put one crossmember of different style and it fits right and functions well.

[FarnorthMN]

@Vladislav I think you are 100% right I did find one that looks very similar to what I have off a 88 DM600 that looks like mine only flipped over.   Think im still going to find 9QL4551M back to back that seems to be stronger and cheaper.   otherwise just reweld and fix what I have.   

5 hours ago, Vladislav said:

Looks like Mack used different styles of the crossmembers which played their role equally. Some trucks had the style your truck have, some those flat style doubles. That's for 80's years and maybe earlier. Don't know the reason. Options? Or just supplys from different vendors? My R's are Canadian built (actually assembled) and they look slightly different in a few points than typical US production vehicles. Of what I noted (if I'm not wrong) a certan chassis has all the crossmembers of the same style (what makes sence). But practically it doesn't look any wrong if you put one crossmember of different style and it fits right and functions well.

 

[Vladislav]

On 11/28/2025 at 4:19 AM, FarnorthMN said:

@Vladislav I think you are 100% right I did find one that looks very similar to what I have off a 88 DM600 that looks like mine only flipped over.   Think im still going to find 9QL4551M back to back that seems to be stronger and cheaper.   otherwise just reweld and fix what I have.   

 

If you look at the #2 photo in the set of pics I posted you may find there was a back to back style using two crossmembers like yours. This way you could make a such one using your old part and that piece of DM. And that would be much stronger than just repair of your original part. But as far as I understand DM must be narrower.

Also a berry from the same field - what is 9QL4551M? Is that exactly for Superliner? And for which frame? Single? Or triple?? I ask because those in my R-model are also 9QL-something. I don't keep the digits in my mind and haven't found them in the computer. But those would definitely be different from what you need by the width. At the same time looking almost identical on a picture.

 

[FarnorthMN]

@Vladislav i have seen 9QL4551m on some superliners couldn't tell if they were single or double frame.  I also have them sending me some demention on the 9QL4551M. We are just getting done with the holiday weekend so things a little slow right now should hear tomorrow.  If neather one of them work I'm going to just fix what I have and get the welder out 😝

[BottleHauler84]

21 hours ago, Vladislav said:

If you look at the #2 photo in the set of pics I posted you may find there was a back to back style using two crossmembers like yours. This way you could make a such one using your old part and that piece of DM. And that would be much stronger than just repair of your original part. But as far as I understand DM must be narrower.

Also a berry from the same field - what is 9QL4551M? Is that exactly for Superliner? And for which frame? Single? Or triple?? I ask because those in my R-model are also 9QL-something. I don't keep the digits in my mind and haven't found them in the computer. But those would definitely be different from what you need by the width. At the same time looking almost identical on a picture.

 

@Vladislav from what I've encountered,  the QL4551M is whats on RW Superhauler 2 and MH Ultraliner 1/4"( or 6mm) thick rail frames. On the the double frame RW or MH, I've seen 9QL4551M2 used. Also, I've seen 9QL4551M2 used on single frame RW2 and MH with 1/4" thick spacer plates in between the crossmember and rails. 

The ones used on the R models were i believe 9QL4551M8. The were a bit more narrow to accommodate the narrow frame rails of those trucks. 

[Vladislav]

14 hours ago, BottleHauler84 said:

@Vladislav from what I've encountered,  the QL4551M is whats on RW Superhauler 2 and MH Ultraliner 1/4"( or 6mm) thick rail frames. On the the double frame RW or MH, I've seen 9QL4551M2 used. Also, I've seen 9QL4551M2 used on single frame RW2 and MH with 1/4" thick spacer plates in between the crossmember and rails. 

The ones used on the R models were i believe 9QL4551M8. The were a bit more narrow to accommodate the narrow frame rails of those trucks. 

This sounds right since R-model frame is a bit narrower than RW2/MH. I have the crossmembers off the R apart sandblasted and painted. So can check out the stampings if needed. Interesting point of using shorter crossmember with spicer plates on the single framed RW/MH. One of my MH's (I have them two) has the very rear beam arranged that way, with spicers at the ends. It's a single frame 1/4" chassis. But it's two stamped shells of the style the original discussion was about, welded together.

Also remarkable point is the 2nd MH has the crossbembers off a R/DM. It's Camelback with single 1/4" rails. Sure those parts are wrong for the truck and the rear engine mounts are put on the chassis brackets using spicers to elevate them a bit (for an inch or so). Originally I was surprized seeing the engine lifted up that way but the owner couldn't say anything on that. And later I found the rear of the chassis became narrower than it should so the engine mounts couldn't fit right and somebody in the past arranged the spicers to clear up the edges of the frame rails they would interfere otherwise.

Thank you for the part ##.

[FarnorthMN]

@Vladislav @BottleHauler84 just talked with a guy on the phone today and he clams this is the cross member thats suppose to be on on the rear.  I find it interesting becuse I have the same crossmember for the cab air ride suspension about the middle of the frame.  I mesured everything on mine today and if I can read a tapmesure should bolt right up and also work with the rear shocks. I still like one @BottleHauler84 has given me better 

 

 

[BottleHauler84]

10 minutes ago, FarnorthMN said:

@Vladislav @BottleHauler84 just talked with a guy on the phone today and he clams this is the cross member thats suppose to be on on the rear.  I find it interesting becuse I have the same crossmember for the cab air ride suspension about the middle of the frame.  I mesured everything on mine today and if I can read a tapmesure should bolt right up and also work with the rear shocks. I still like one @BottleHauler84 has given me better 

 

 

I can confirm that the crossmember in your picture was in fact used on a RW2 and MH frame. I have that exact crossmember on my 1993 MH at the rear most crossmember position,  however, it uses 1/4" thick spacers with it to fit correctly and thats from the factory. 

I've also seen that style on several different trucks.  My 2002 CXU uses that same crossmember it at the rear most position as well, but no spacers. One thing I dont like about that particular style is I've seen alot of those get rust jacking in-between those welded together stamped crossmembers. If you can find a nice one, they are OK. Otherwise you have cut the welds, split them apart, blast the rust and repaint and then weld it all back. That sucks in my opinion. 

I prefer the simple 1/2" thick 90L4551M like we been talking about.  I agree with you there, but that crossmember in the picture will work if you decide to go that route....you just might need spacers depending on the measurements of that particular one. 

[FarnorthMN]

2 minutes ago, BottleHauler84 said:

I can confirm that the crossmember in your picture was in fact used on a RW2 and MH frame. I have that exact crossmember on my 1993 MH at the rear most crossmember position,  however, it uses 1/4" thick spacers with it to fit correctly and thats from the factory. 

I've also seen that style on several different trucks.  My 2002 CXU uses that same crossmember it at the rear most position as well, but no spacers. One thing I dont like about that particular style is I've seen alot of those get rust jacking in-between those welded together stamped crossmembers. If you can find a nice one, they are OK. Otherwise you have cut the welds, split them apart, blast the rust and repaint and then weld it all back. That sucks in my opinion. 

I prefer the simple 1/2" thick 90L4551M like we been talking about.  I agree with you there, but that crossmember in the picture will work if you decide to go that route....you just might need spacers depending on the measurements of that particular one. 

Thank you @BottleHauler84 im glad you mentioned the rust jacking l love working on this stuff but a absolutely hate doing things twice. And I plan on keep the truck for a long time.  

[BottleHauler84]

5 minutes ago, FarnorthMN said:

Thank you @BottleHauler84 im glad you mentioned the rust jacking l love working on this stuff but a absolutely hate doing things twice. And I plan on keep the truck for a long time.  

I like doing stuff right or the best I can the first time.  Theres times I've had to do things to get by or a quick fix i can do and go back later if necessary.....but a crossmember aint one of those times lol, im with you there. Especially on a nice truck like yours. It won't take much to make a super nice truck out of it. Its a good looking ride for sure.

[FarnorthMN]

16 minutes ago, BottleHauler84 said:

I like doing stuff right or the best I can the first time.  Theres times I've had to do things to get by or a quick fix i can do and go back later if necessary.....but a crossmember aint one of those times lol, im with you there. Especially on a nice truck like yours. It won't take much to make a super nice truck out of it. Its a good looking ride for sure.

Thank you sir.  Im getting everything thing mechanical sound and leak free this winter.  Going to run some equipment up north on lowboy first thing in spring make sure everything is dialed in.  over the summer plan on pulling cab and hood blasting/paint frame and engine. sand,prime, and paint cab and hood.

 

sooo in all honesty Will probably take me two years 🤣🤣

[Vladislav]

17 hours ago, FarnorthMN said:

@Vladislav @BottleHauler84 just talked with a guy on the phone today and he clams this is the cross member thats suppose to be on on the rear.  I find it interesting becuse I have the same crossmember for the cab air ride suspension about the middle of the frame.  I mesured everything on mine today and if I can read a tapmesure should bolt right up and also work with the rear shocks. I still like one @BottleHauler84 has given me better 

 

 

Yes, this crossmember is supposed to be on the rear. I have a similar one on the rear of my MH. With spicers at the sides and put with the dish up. Very probably you have a similar part as the cab support but I expect that to be a single beam. If that one is double like the one in the pics I'd like to see your cab air ride setup.

Good luck on the fix and future plans!