ARP main stud issue...

[johnbureezu]

I know it's been while since i posted, but I'm finally gettin to puttin my motor back together. Anyway, right now I'm having issues installing my ARP mains. Its an SR20DET also.
Well, it says to torque to 80-85 ft/lbs when using 30wt oil and 75 when using arp moly lube. Don't have any arp moly but I had some 30wt. When I plastigauged the first time, I noticed 3 and 4 were a lil out of spec. So I went with higher grade bearings on those journals. Plastigauge and now they are all within spec (.025mm) So now I go to install the crank with lube (30wt on the bolt threads and torco assembly lube on bearings) and its friggen tight like a tiger! Torqued to 80 ft/lbs. So then I try 70 ft/lbs and it loosens up a bit...wtf? I'm thinkin the torco stuff is too thick or something. Anybody ever intall these bastards on thier SR? Worse comes to worse, OEM one are finding their way back in.

Thanks

[let5l1de]

I didn't see you mention the ARP studs were hand tightened all the way down. I highly doubt your problem is with the ARP studs. Did you follow the correct torque sequence?

Since your main bearing clearance seems to be within the OEM specifications, I would be quick to say your crankshaft end play has not been set. The end play should be 0.10 - 0.26mm or 0.0039" - 0.0102" with the limit at 0.30mm or 0.0118".

I'll give you a hint. THRUST BEARING. This is another crucial measurement that is often overlooked and will bind your crankshaft if not set right. If extremely loose (not in your case?), your crankshaft will walk all over the place disintegrating your rod bearings without a doubt.

Tell us what you found.

btw: Please confirm you have not installed the rods onto the crankshaft while checking the clearances on the main right?

~mario

[wings_s13]

^^ took the workds right out of my mouth. I have arp studs, and have never had a probly with them. i would start rechecking everything. sadly plastic gauge is a great inexpencive tool, but will not give u spec or point out the problem one way or another. good luck would like to know what u find as well.

chris

[johnbureezu]

I didn't see you mention the ARP studs were hand tightened all the way down. I highly doubt your problem is with the ARP studs. Did you follow the correct torque sequence?

Since your main bearing clearance seems to be within the OEM specifications, I would be quick to say your crankshaft end play has not been set. The end play should be 0.10 - 0.26mm or 0.0039" - 0.0102" with the limit at 0.30mm or 0.0118".

I'll give you a hint. THRUST BEARING. This is another crucial measurement that is often overlooked and will bind your crankshaft if not set right. If extremely loose (not in your case?), your crankshaft will walk all over the place disintegrating your rod bearings without a doubt.

Tell us what you found.

btw: Please confirm you have not installed the rods onto the crankshaft while checking the clearances on the main right?

Thanks for the fast reply. Yes, the studs were set hand tight then torqued 10 ft/lbs at a time till I hit 80 ft/lbs. No rods were installed at this time. As fort eh thrust washers and endplay, I have not checked it. The thrust washers are brand new, how do make adjustments to endplay? Also, I didn't have the block line bored either. Almost ready to slap some new OEM bolts if it comes to that.

[let5l1de]

Adjustments are typically made by grinding the face on either side of the thrust bearing.

Measure the end play. Let's use 0.20mm as the target and subtract 0.xxmm (your measured end play). This number will be the total amount material to be remove from the thrust bearing. Divide the total amount by 2. This gives you the number of how much material to remove from the front and rear of the thrust bearing (assuming your crank is centered).

example:

Your End Play measures 0.05mm (too tight)

Target End Play is 0.20mm (or between 0.10 - 0.26mm as previously stated. Use 0.20mm)

TEP 0.20mm
-
YEP 0.05mm
______________
= 0.15mm (Total Machining Needed)

TMN 0.15mm
÷
2
______________
= 0.075mm (amount of material to be remove from the front and rear of thrust bearing)

~mario

[S14DB]

When you switch from Main Bolts to Studs you have to have the crank bore checked. Most of the time you have to have it line bored. The studs clamp down differently then the bolts.

[Sileighty_85]

well if you decide to back to bolts

Pulsar GTI-R Main Crank Bolts 10% stronger over regular SR bolts

12293-54C00

[johnbureezu]

Quick status.... I removed the ARP studs and plastigauged again, but this time with old stock bolts and 61 ft/lbs. Now my clearances are in the .038 range with the same bearings. Weird. Shouldn't the clearance be the same with or without the ARP hardware?

[S14DB]

Quick status.... I removed the ARP studs and plastigauged again, but this time with old stock bolts and 61 ft/lbs. Now my clearances are in the .038 range with the same bearings. Weird. Shouldn't the clearance be the same with or without the ARP hardware?

Did you read my post?

[johnbureezu]

Yeah, read your post. And.....? What if I go back to bolts? Still gonna have the main bore checked but I'm doing what I can in the meantime. Tryin to avoid having to get the block machined and have to buy a whole 'nother set of bearings. I've built a few motors before, but this is my first time using ARP studs.

[S14DB]

Bolts should all be the same clamping load on the caps.

Studs put a different load on the caps. Causes them to deform differently under Tq then with bolts. They will be out of round until you get them line bored.

If you had your block machined with bolts it will be easiest to put new bolts in. To go to studs would mean having it line bored possibly needing new bearings also.

[let5l1de]

My initial statement about ARP studs may be misleading.

It is possible to be misaligned due to all clamping forces being on one axis with ARP Studs. This increases the clamping force without increasing the actual ft-lbs of torque at the nut even at factory torque specifications. With that said, proper alignment of caps or main girdles (depending on factory tolerances) should be the result every time.

Remember, the studs should be inserted into clean thread in block only finger tight to prevent stud misalignment within the block. Also remember to torque (in proper sequence), loosen and re-torque the main studs at least 3 and up to 5 times prior to the final torque to set the correct preload on the studs. Note: Torque specs will vary depending on lubricant.

So, with the new clamping force axis (ARP Studs), torqued to specs and a true crank girdle alignment (without crank or bearings), pull out your gauges and check your tolerances. If out of roundness or residual stress in the castings has been diagnosed, leading to poor crank alignment, you may need to align bore or align hone the block.

Every engine build requires its own respective diagnosis and blueprint.

~m

edit:
Oh... If you read the he fine print, it may also say not to use any other kind of moly lube or main cap walk could result.