Phoenix1

iTrader: (1)

I had a four-wheel alignment done on my '97 Prelude at my local Honda dealer.When the job was completed, the service advisor told me that my car aligned perfectly and that only a slight subframe shift was necessary. When asked just what the hell a subframe shift is (something that she told me they charge for. Yes, a she.), she told me that sometimes the car won't align to spec, and when that happens, a shift is necessary. When pressed further about the issue, she called the tech that performed the alignment. I asked to speak to him, and here is what he told me:

1. He had to shift the subframe to reset to neutral chassis.
2. A subframe shift is necessary to correct the car pulling to one side.
3. A subframe shift is done because caster is off.
4. Adjusting toe will not correct the pulling to one side problem

When I asked him "how" he shifted the subframe, i.e., if he actually lossened the bolts of the subframe and "shifted" it, he said yes, that it was off 7/10 of an inch. Yes, an inch.
I told him that my factory service manual makes no mention of such a procedure, he got a little angry and told me that he did it for free, and that the dealer normally charges for it.

Now, this obviously sounds like a load of ****, but before I flip my lid for the bogus information (the quality of the job notwithstanding and just in case by some strange incomprehensible reason I've never heard of this and it's actually a legitimate procedure), is this a valid procedure?

Thanks for your time.

Accordin2me

Makes (a little) sense but i've never heard of it being required unless the front end got wacked pretty hard. If they didnt charge you for it I wouldnt get too wound up about it.

Update: Just got off the phone with a honda Service manager & a Tech buddy of mine who works at said dealer, It's bullshyt you cant "shift" the subframe & 7/10 of an inch is clearly b.s. RAISE SUM HELL!

PPLH8R

The subframes can be more or less adjusted, but not by 7/10 of an inch. You can loosen the subframe and use a prybar or similar tool to get the subframe to move and get the numbers you are looking for on the alignment rack.
I have never really measured but if my memory serves me correctly you can probably move the subframe by 1/4 " or so but not much more than that.
BTW Worked for Acura 4 yrs. and Honda for 2 yrs.

mouab18c1

iTrader: (5)

OP ask in GDD they have a thread just for licensed mechanics.

spoonfedcrx

I've had to shift subframes before. Usually these were on cars up from the bodyshop. Basically just loosening the bolts and a big *** pry bar. Helps to have another body sometimes.

soon2bdropped

yes you can shift a subframe. i do it all the time. dont know about 7/10 of an inch.. i do it often though.

Phoenix1

iTrader: (1)

The subframe bolts are sized so that the hole in the subframe itself is a locating hole. The bolt is flared to accomodate an interference fit, so how can the subframe "move" if the bolt locates the subframe? Also, why isn't such a procedure mentioned in the FSM? I can understand the need to do something like this when the car is in an accident and the frame itself is out of spec, but not for an alignment on a vehicle that has not been in an accident.

Chiovnidca

Shifting the subframe is commonly done to even up the camber spec from one side to the other if there is a big difference between them. (enough of a difference to cause the car to pull) Caster can be evened up the same way. So no, the guy wasn't bullshitting you, and as far as i know there's no mention of it in the factory service manuals. It is mentioned in a number of service bulletins though.

Phoenix1

iTrader: (1)

I'm going to presume that you are or were a Honda/Acura tech: what TSB bulletins mention this? And how can this be accomplished seeing that the subframe mounting bolts are locating bolts, and the holes in the subframe are not clearance holes?

99blackcivicSi

which subframe did he shift the front or the rear (you have a two piece on your car in the front)

Phoenix1

iTrader: (1)

Funny you ask that. When I asked him the same question, he told me my car only has one (lol). Anyway, he claims to have shifted the rear cross beam (as it's called in the FSM).

non-VTEC

its a common procedure and honestly you shouldn't question it....if everything is aligned to spec why would it matter?

over time suspension components wear/sag and with enough stress and fatigue on all the suspension joints/bushings/components sometimes you need to do things the repair manual does not mention.

Phoenix1

iTrader: (1)

Why the hell not? If you saw a orthodontist to get braces, and they told you a jaw shift may be needed, wouldn't you want to know just what the hell that is all about? I'm exaggerating, but it's my car and I have a right to know things of this nature, regardless of whether the car needed it or not.

The FSM outlines procedures to correct the issues you stated. What bothers me is the fact that I've never heard of such a procedure in addition to how it is performed, seeing as how THERE IS NO ROOM FOR ADJUSTMENT IN THE DESIGN OF THE SUBFRAME.

Additionally, I spoke with an old friend who is a Honda Silver certified tech, with 20 plus years under his belt. He told me the whole "subframe shift" is bullshit. I chose to post the matter to verify his claim, for the sake of legitimacy.

AccordVT

Shifting the subframe can change caster, yes. Though this change will be minimal if any and cause an equal and opposite change in caster on the other rear wheel. Caster will make a car pull to one side, though typically, out of spec caster in the rear will not cause as strong a pull. Adjusting toe cannot remedy a pull to one side as toe has no effect on a pull, the mis-adjustment of toe only offsets the steering wheel.

Usually when a tech gets a car on the rack and is unable to adjust caster and toe through the traditional and factory specified methods, they revert to non-traditional methods. These usually unorthodox methods, vary from hammers, big prybars, portable power rams, torches ect. Moving the subframe is not common; though I can see how it would be more so on a honda with less factory adjustment. There is no way he moved the subframe anywhere near 7/10". If you can move the subframe on your car more than 1-3mm with the bolts still in it, there is some separate and larger issue going on.

I would want to know the numbers; The initial, after the attempt to do it the right way and then after the subframe "shift". He may just be saying he used the "subframe shift method" to convey to you that he did not do it the correct and specified way; assuming you wouldn't second guess whether the subframe could actually move that much. Look carefully at your car when you can and see if he didn't use some other sort of method. Usually if someone got in there and was trying to get the correct numbers...there will be some evidence of so.

Alot of techs seem to fall into a pattern of pulling cars on, being in a time crunch obviously and just wanting to get those numbers to say what they should be. They will do whatever they feel necessary to get the numbers right. What you must keep in mind is that when an adjustment is indicated out of spec by the alignment machine, this can be for alot of reasons. Sensor calibration, sensor mounting and other rack issues could be the cause. The main one to consider, in this case especially, if caster is out of spec, something could be bent, worn or damaged. A badly worn bushing, a bent lower control arm or damaged shock can cause an out of spec caster reading. Using unorthodox methods to ensure a correct reading is putting a band-aid on the issue. Remedying a symptom instead of addressing the cause of the problem.

non-VTEC

your lucky all it needed was a subframe shift....would you rather have him replace hundreds of dollars worth of parts to correct out of spec caster? out of the hundreds of "out of spec" wheel alignments i have done not one customer is willing to spend 1 penny more then the actual cost of the wheel alignment itself....trust me.

i've been a tech for over 10 years....it's done more than you think. the service manual is only a guideline not the bible....trust me...if you worked in the hell hole of a flat rate pay system you find ways to make things work in the short amount of actual paid time.

Phoenix1

iTrader: (1)

non-VTEC, I'm not questioning the frequency of the procedure, I'm questioning how it's done, i.e., how can a subframe be shifted when the bolts that secure it to the vehicle frame are locating bolts?

Chiovnidca

The holes are bigger than the bolts so there's room to move the beam around a little bit. Usually enough to change things .2 - .3 degrees a side, sometimes a little more.

jjspec

There is no caster or camber adjustments on a Honda. On a Prelude/Accord, you can add shims to the radius rods to get some Caster adj which will affect a camber adjustment. But you can shift the rear crossmember and get some adjustment.

Phoenix1

iTrader: (1)

Hmmm, my interest in this subject is piqued further. While reading the FSM about subframe removal/replacement, it clearly states that when the subframe mounting bolts are loosened, they must be replaced. This means that a subframe shift is NOT the proper procedure.

If the tech could not get the proper alignment numbers, I should have been notified, because a subframe shift is not the correct method to achieving proper specifications. The root of the problem lies in worn bushing and/or a previous crash, and a subframe shift is a band-aid solution, something I abhor with great passion. The tech told me that my caster numbers were off, and the proper procedure would have been to shim the radius rods, not shift the subframe.

Thank you to all for your input. I don't mean to doubt anyones advice or information, but I don't believe this is a valid procedure, certainly not something that should normally be charged for at the dealer.

If it makes any difference, I'm a mechanical engineer and I tend to follow the FSM religously, to a "T". I demand proper answers to technical questions, and the tech's answers to my questions only served to upset me, especially the bogus numbers thrown out. I've built numerous engines, tuned many cars on many engine management systems, performed right-hand drive conversions, etc. I was contracted by a Honda dealer in my hometown to tune modified vehicles sold with power adders. I drag race, road race, and do motorcycle trackdays. I do not wish to brag, I'm simply stating this "for the record", so I don't come off as an ****-retentive ***** who doesn't know **** from apple butter.

Again, thanks to all.

DCFIVER

Wrong. It is the proper procedure.

Wrong. As a last resort a subframe shift is the factory recommended procedure.
For a mechanical engineer who "modifies" cars you sure seem only capable of thinking "inside the box". The FSM is for noobs or the inexperienced just learning the ropes. I love when guys like you come to my job and try to tell me Im wrong because your service manual says so. There are constant updates to service procedures that your FSM cannot show you. One such procedure is TSB#06-068. Another is SN030915. This not a TSB but rather a service bulletin intended only for dealer technicians with access to ISIS. That is Hondas technical information network. These are Hondas most current procedure for doing alignments and includes a subframe shift for both caster and camber correction. You are also wrong about the bolts being locating bolts. They are not. And the only reason Honda reccomends replacing the bolts is because the bolts are coated from the factory with a loctite like compound. If you simply replace the compound with ,well,Loctite (blue) the bolts are fine to reuse.

(BTW 10 year ASE certified and L1 tech. Honda Factory trained. Many "dealer" technicians cant even make this claim.)

DCFIVER

The service manager is clueless and your tech buddy is probably an LOF guy. Refer them to the TSB and Service News that i mentioned in the above post.

Mikey3000

post a pic of a subframe please. i don't know wtf that is.

99blackcivicSi

subframes and cradles do have movement in them a few millimeters at most but yes they do move i have shifted subframes around in many vehicles from infiniti to acura.

7/10's of an inch is a LOT and theres no way it was shifted that much...

that surface coated bolt to be thrown away is a load of **** theres no stretch on them they are good if you don't over torque them read through a honda FSM and see how many bolts they want you to throw away when you do ANYTHING do i reuse them? yes i sure as hell have i ever had a comeback becuase of it no sir i have not.

i'm going on my 10th year turning wrenches am an infiniti master (which requires a1-a8 ase's) and now i've been with honda for a year.

If you can't shift the subframe then why oh why on a vehicle is a cradle should you alin it afterwords? can you answer me that oh i know because theres excess play in the bolt holes (honda even gives you two holes on the rear to align them where they should be but its never perfect where the factory set it) and when you change any spec you knock toe out a little bit...kthnx

Mikey3000...your car vehicle has a subframe look at what the power steering rack is bolted to thats it.

DCFIVER i looked at some new bolts i had today from a R series short block i don't even think its loctite there no blue just a coating on probably less than blue loctite the weakest there is. If your scared about removing these bolts becuase its not the "fsm procedure" take them out totally and replace the bolt before shifting the frame don't tighten them up all the way before you do so or run them all the way out and put blue loctite on it simple as that.

Scott_Tucker

I agree he's over-reacting. Unless there's body panels misaligned or something what is there to be mad about? The guy was just trying to align the vehicle, most customers would be stoked that he went to the extra effort to do this.

Mechanical Engineer does not equal Automotive Tech. They are two completely separate fields that are unrelated. Engineers design things. Technicians troubleshoot and fix things.

DCFIVER

Only suspension bolts are coated that i am aware of. It is a green thread locking compuond. but yes as i stated earlier they can be reused by simply applying blue loctite.