Rb30 Bearings In Rb26

[Mik]

It is acceptable to use bearings of adjacent size together on the one journal to get the required vertical oil clearances eg a .025 shell with a STD shell

Product Engineering ACL Bearing Company

<{POST_SNAPBACK}>

So, it's okay to use one HX shell and one H shell on the same conrod journal (to give 1/2 thou extra cleanace)?. Will the missmatch at the parting line cause issues?

[Sydneykid]

So, it's okay to use one HX shell and one H shell on the same conrod journal (to give 1/2 thou extra cleanace)?. Will the missmatch at the parting line cause issues?

<{POST_SNAPBACK}>

Yep, done all the time

cheers

[Mik]

Yep, done all the time

cheers

<{POST_SNAPBACK}>

Thanks...another question. The nissan standard RB26 big end oil clearance is 0.0008"-0.0016". Realistically, will a clearance of about 1.2-1.3 thou be too tight? Would an extra 1/2 thou be better?

[blk180]

Dam nice of acl to post. Now to see if the engine shop put those extra 4 holes in my bearings( cross fingers )

would this be notice stright away ie i have done just over 5000kms now would have stuffed up by now if they did not drill those holes

Edited October 28, 2005 by blk180

[Duncan]

Good to see ACL posting directly

Now, when an ACL RB30 bearing spins after 2000klm, how does one work out what the cause is? just hypothetically of course

[proengines]

Good to see ACL posting directly

Now, when an ACL RB30 bearing spins after 2000klm, how does one work out what the cause is? just hypothetically of course

<{POST_SNAPBACK}>

I might have an answer to that problem, we had an engine come in recently with a similar problem and the main tunnels measure spot on for diameter but the tunnels were out of alignment. It chewed out the main bearings within a couple of thousand km. I machined the cap registers and closed up the tunnels to hone them but after honing the tunnels aren't quite spot on so we are starting with another block. It might be worth running a straight edge along the main tunnels or the cap registers and checking. This block measured .003"-.004" out when I set it up in the mill and checked it with a dial gauge. The crank would have been running bent the entire time and you could see where it had been running hard against the bearings by the marks on the main journals so there was no oil film between the crankshaft and the bearing in different spots. Tunnel boring it would have increased the piston protrusion and affected the oil pump alignment so that wasn't an option.

Speaking of ACL, I had a visit from Paul from ACL last week and had a good discussion about bearings and from that, and because our current supplier of King bearings has for some reason decided to stop importing them, I'm going to change to the ACL race series bearings for the RB's and use them in 2JZ's. It's nice to see a company that does stand behind their product and takes input from their customers seriously.

Edited October 29, 2005 by proengines

[WetGTR]

Good to hear from you Greg!

How would the tunnels go out of alignment? Could an engine builder do that?

Could it be that if a block was tunnel bored that could also cause a mis-alignment problem?

It seems that its not too hard spinning a bearing but at so low km there is defiently a problem. I think it's more about the engine builders ability then it is on the parts. Also it seems that RB26 have alot of bearing problems but I haven't heard many people spin or have bearing problems in RB30's.

Are they not the same block design?

I understand that RB26 rev alot higher then the RB30 but is this the only reason?

Edited October 29, 2005 by WetGTR

[Duncan]

Thanks proengines, good point about the tunnel alignment. The crank that went in was checked for straightness but I am not sure about the tunnel itself.

Any other common causes?

[haw001]

Yes, a bag of bolts in the intake!

Not that I can talk

Thanks proengines, good point about the tunnel alignment. The crank that went in was checked for straightness but I am not sure about the tunnel itself.

Any other common causes?

[BoostdR]

ACL Bearing Company is aware of the RB30 main bearings 7M2394H being used in RB26 prior to the RB26 mains 7M2428H being introduced and we believe these have functioned quite satisfactorily, however

the differences between the two sets are:

1) the RB26 upper mains have 5 oil holes and the RB30 has only 1 (engine builders were drilling the additional holes)

2) the RB26 plain mains are 20 mm wide vs 19mm for RB30- The 19mm wide bearings have been functioning quite satisfactorily as the ACL 7M2428H was introduced with 19 mm wide mains, however since having a number of requests for the 20 mm wide bearings, we will be making a running change to the 7M2428H set, which should be available approx late December 05. (the additional 1mm is an equal 0.5mm per side)

3) the Flanged main for the RB26 is .002" (0.050 mm) wider than the RB30 main, so endfloat will be slightly different if RB30 mains were used (this may still be within acceptable limits)

The ACL RACE bearings premiumTrimetal bearingsand are specifically designed for high performance engines. The material used is a high strength copper lead material bonded to a steel backing, with an improved strength overlay, for added fatigue strength. Con rod bearings have a hardened steel backing material which helps maintain their crush under higher load and temperature conditions during operation.

Design features-

Bearing eccentricity- (i.e the reduction in wall thickness from the thickest section at the crown of the bearing to the point 10mm from the parting line) is increased to compensate for bore distortion which will occurr due to higher inertia loads, and to assist with formation of the oil wedge to build thevital hyrdrodynamic oil film which seperates the shaft and bearing, to prevent wear. This also helps to maintain a good oil flow through the bearings, essential for heat dissipation away from the bearings.

Crush-is the amount the shells are circumferentially longer than the true half diameter of the housing bore. Crush is increased on these bearings for improved bearing retention and heat disipation.

Wall size tolerance is +/- 0.004 mm (+/- 0.00015") for consistent vertical oil clearances.

The trimetal bearing is a high load carring bearing, with good surface properties(i.e seizure resistance, dirt embedability, conformability) with enhanced chemistry of the overlay plated surface layer for improved fatigue resistance. Fatigue resistance is also improved on the con rod bearings by reducing the overlay thickness to 0.013mm (0.0005"), and there is no flash plating on the bearing backs, so there is no "migration" of plate on the bearing backs under heavy loading, improving thermal transfer and seating of the bearings in their housings.

These bearings are available in 7M2428H -STD/0.025 / 0.25/0.50

7M 2428HX-STD (this gives 0.025 mm(0.001") extra clearance over the 7M2428H-STD)

6B2960H-STD/0.025/0.25

6B2960HX-STD

RB 25 uses the same main bearings as the RB30 7M2394H/HX

Same con rod bearings as the RB26 6B2960H/HX

It is acceptable to use bearings of adjacent size together on the one journal to get the required vertical oil clearances eg a .025 shell with a STD shell

Product Engineering ACL Bearing Company

The RB26 2428H ACL RACE bearings are indeed 20mm wide now however when compared against the Nissan Bearings have a smaller contact area. 18.6mm(ACL) compared to 19.3mm(nissan) The ACL however are all grooved for added oiling.

Matt

[zebra]

Errr Matt.

Did you check the date of ACL's post?

[BoostdR]

Yes, I am well aware. Thankyou.

[G37Sam]

Sorry for bumping an old thread, but a vendor sent me RB26 ACL main bearings for my RB30 by mistake. The diameter is the same but my understanding is that the RB26 one is 0.8mm wider and that it has more oil holes (better cooling/lubrication?)

Should I send these back or do I just stick them into my RB30?