Thread: .120 Gap Spark Plugs, New Cone Filter install, New Wires and Road Trip. Worst Plugs.

Ok so I'll find a spare ECM and probably just send off for a pre boxed tune. I am a computer tech by trade so I don't think doing the tune myself would be that much of a hastle, however honestly I am not "their" yet at this stage of the building with the car. Right now I am just worried about getting the most out of the semi stock car that I can. I mentioned earlier, that I was going to take the car in to a local shop for an oil change, not because I could not do an oil change myself, but I wanted to get the car up on the hoist and inspect the undercarriage of the car. Well what I found totally blew my mind and is very unexpected.

Looks like the left rear control arm / trailing arm was hit or damaged. There is no body damage and no rim damage, so best I can figure is someone (not me) tried to jack the car up from there and bent it.

It must be a fairly old issue, and the car has since been alligned to take into account the shorter control arm. The car tracks perfectly straight and handles well. None the less I am going to try and locate a new control arm asap.

Here is a pic of the damage control arm.

It's a common thing for these cars honestly. A lot of people try jacking them up there and bend them, they don't realize that the arms are not made for handing a load. Also, they are not control arms, they're trailing arms.

The GMPP trailing arms are not Discontinued actually. The would likely have to be special ordered, would take a couple days, but they are in the warehouses.
GM #25990164 - retail $40 each

Call your local dealer and see if they can get them.

EDIT: Keep in mind the factory replacement POS like you have that is bent is GM# 10282766 - Retail $77.00. Give them the # and have them price it and tell you when they can get it. Don't just give them your vehicle info, it won't match. The GMPP is for an impala.

You can go aftermarket with them, my UMI arms were $110 and are super beefy.

Originally Posted by SnowFlake

Get some headers on there man... your plugs indicate it's knocking pretty badly.

Joke? He's totally stock and all I see are worn plugs. No bent side electrodes or anything that I'd consider relevant to abuse within the chamber.

Originally Posted by matt5112

At least go for boxed ones.

IIRC the dormans are boxed.

If you wanted to go used part hunting, impala cop cars had tubular bars from the factory.

GM used to sell those as GMPP but they've been discontinued.

I was thinking that I would find someone on here with a good used OEM one, however further posts have me thinking twice about that.

Originally Posted by chrisatpsu

wow, that is weird... the buckles on each side are both in the same direction so at one time it was bent to the side.
If it was jacked up and that made it bend, you should have seen both buckles in an outward motion... at least the civil engineer in me tells me so...

Honestly your guess is as good as mine. However with Zero body damage or rim damage, the only thing that I can think is a jack or gasp someone drove off a curb really badly.

Originally Posted by RooK

It's a common thing for these cars honestly. A lot of people try jacking them up there and bend them, they don't realize that the arms are not made for handing a load. Also, they are not control arms, they're trailing arms.

I have seen this before on 88 Fiero's, and in the Fiero's case, there are no replacements, GM quit making them years ago, and NO other car ever used an 88 Trailing arm. Last I checked there was 1 aftermarket company charging $450 for a set. Which may no longer even be around.

Originally Posted by TLSheff

The GMPP trailing arms are not Discontinued actually. The would likely have to be special ordered, would take a couple days, but they are in the warehouses.
GM #25990164 - retail $40 each

Call your local dealer and see if they can get them.

EDIT: Keep in mind the factory replacement POS like you have that is bent is GM# 10282766 - Retail $77.00. Give them the # and have them price it and tell you when they can get it. Don't just give them your vehicle info, it won't match. The GMPP is for an impala.

So if I am reading that right, I can pay $77 and get a weak OEM, or $80 for a set of the better ones. It does not sound like a good idea to have one OEM and one upgraded trailing arm. Thank You VERY MUCH, for all the part numbers will make it much easier.

Originally Posted by Sandman

You can go aftermarket with them, my UMI arms were $110 and are super beefy.

If I were going to take this car out Autocrossing or Road course I would probably go with something extra heavy duty, but as much fun as I am having with this car, I keep forgetting that this car was bought to haul around our 2 year old and soon to be born new baby. I think upgraded stock parts will be fine. However thank you for the info, I'll keep it in mind.

Originally Posted by SnowFlake

Get some headers on there man... your plugs indicate it's knocking pretty badly.

Originally Posted by RooK

Joke? He's totally stock and all I see are worn plugs. No bent side electrodes or anything that I'd consider relevant to abuse within the chamber.

Originally Posted by SnowFlake

Not a joke at all... those plugs are covered with signs of knock. Must have been really bad to leave layers like that on the plug.

The car was owned for 11 years of its life by a nice old couple, however directly before we bought it, it was owned by another guy for 4 months, it is possible that he ran cheap gas in it, then drove it rather hard. As well as the really bad plugs, the combustion chamber temps could have been hot enough to get some pre-ignition. However now that we own it, it will finally get treated right with a steady diet of 94oct and good parts with regular maintenance and regular ECM scans to keep an eye on KR.


Thank You Everyone, you have all been amazing with the help.

Originally Posted by Capt Fiero

I have seen this before on 88 Fiero's, and in the Fiero's case, there are no replacements, GM quit making them years ago, and NO other car ever used an 88 Trailing arm. Last I checked there was 1 aftermarket company charging $450 for a set. Which may no longer even be around.

Ehhhh? For that price I'd just take the factory one, cut the bent U-channel off, cut a metal rod to length and have it welded between the two ends. Probably be less than $50 per side.

Originally Posted by RooK

Ehhhh? For that price I'd just take the factory one, cut the bent U-channel off, cut a metal rod to length and have it welded between the two ends. Probably be less than $50 per side.

I waited to reply to this thread until I had the cradle out of 88GT. (swapping the alternator, bolt got siezed so decided to just swap the engine along with it, granted the slipping clutch and bad rings did aid in the descsion)

The 88 Trailing arm is not just a straight piece, the angles have to be perfect or else you get bind in the suspension. (all the pics from today are at, May 27th 88 Fiero Engine Pull but didn't want to clog up this thread with too much Fiero stuff)



I have decided to go ahead and grab a pair of Impalla arms and put poly in them. Seems to be a good deal and will get me a start on my poly install for the entire car.

So I see says the blind man. Still... you could make a jig that replicated that angle in a few hrs and still make them for almost nothing.

Originally Posted by RooK

Joke? He's totally stock and all I see are worn plugs. No bent side electrodes or anything that I'd consider relevant to abuse within the chamber.

These cars knocked from the factory. Every last one of them.

HT Motorsports Trailing arms... nice and very reasonably priced.

I can't believe those plugs though... wow! Engine must feel great after changing those out with new wires too.