Does anyone know why the factory service manual says to replace the subframe bolts if they are loosened/removed? I'm refering to bolts numbered 20, 21, 26 & 28 in this pic.



Thanks,
Dave

 

Unless a Honda expert steps up all your going to get is speculation... which is what I'm doing. Maybe the bolts stretch upon installation so are regarded as one-time use.

Just a guess.

 

If you look carefully at the bolts, they have a small nylon insert (usually blue) in the side of the threads. This is a form of threadlocking that Honda feels is a one time use item.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Jaker &raquo;</TD></TR><TR><TD CLASS="quote">If you look carefully at the bolts, they have a small nylon insert (usually blue) in the side of the threads. This is a form of threadlocking that Honda feels is a one time use item. </TD></TR></TABLE>

I know exactly what you're talking about, however these bolts have no self locking insert. If you look in the suspension section of the shop manual, two of these bolts (#21 & #28 in the diagram) are called "flange bolts", which hold the rear swing arm bushing, and also the sub-frame. There is no "replace" warning in this section. There is a third bolt (not shown above) which also holds the rear swing arm bushing, that is called out as a self-locking bolt and is to be replaced if the locking insert is "worn out". They define "worn out" as taking less than 0.7 ft.-lbs. of torque to thread a nut over the self-locking insert.

Thanks,
Dave


Modified by RaceCity_USA at 10:30 PM 5/30/2006

 

Dave, 1/2" bolts at 40ft-lbs are not quite torque to yield fastners,so the reason that honda specifies there replacement when loosened (especially on the aluminum bodied nsx and insight) is that they are darco coated (or similar, I know they darco the bolts for the aluminum bodied cars)
It is recomended that they are replaced because if they corrode, you're pretty much done for. (Can't nutsert something as critical as a subframe connector if it gets stuck and you have to cut or drill it out, you know?.) Most techs will reuse them a couple times in dry climates, but if you plan on driving in rain/salt or if the car has seen those conditions, it's usually a good idea to replace them. I'm told the wait for the bolts can be a couple weeks if they are out of stock however, so be warned. Hope that helps.

 

If you are especially worried about them corroding while in the body apply a light coat of galvanized or rust inhibiting paint. For the most part these should never be a problem unless your municipality pours tonnes and tonnes of salt on the roads.

I have removed these bolts from several severely corroded cars, and even for first time removal some have been corroded to the point where they snap off. Point being if they are going to rust that bad, they will do it regardless of whether or not they have been reused. The dacro coated bolts can be reused up to eight times on the aluminum bodied cars, in which the oxidation of the bolts would be much more prevailant.
That is my $0.02

 

I was told the reason was very similar to what Niles said. Personally I have reused those bolts on several different cars with no ill effects. The helm also recommends replacing most of the suspention bolts and I honestly dont know anyone who does and with exception to the occassional 'frozen suspension bolt' ive yet to see any problems because of this practice.

Good Luck, the car is looking awesome!
-Rich

 

Thanks to everyone for your input on this. I will definitely be reusing the sub-frame bolts!

Cheers,
Dave

 

I replace those bolts reguardless you just dont know what they've been through.

The 1988 Toyota Supra I drove riped its rear frame from too much stress cracked one side and the bolts failed. The same zinc coated bolts that Honda use.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by MidShipCivic &raquo;</TD></TR><TR><TD CLASS="quote">I replace those bolts reguardless you just dont know what they've been through.

The 1988 Toyota Supra I drove riped its rear frame from too much stress cracked one side and the bolts failed. The same zinc coated bolts that Honda use.</TD></TR></TABLE>

I hope they are not zinc coated on your supra.. dacrotized coatings are far superior to just zinc dipped (galvanized) or electro-plated zinc coatings.

Dacro product info & salt spray tests

According to their product info a key element of dacro is scratch surface anti-corrosion, which would seem to indicate the can be reused without concern. However I might replace them if I planned on driving the car in the winter at all... up here they salt occasionally