The Dodge Challenger Message Board

Hi
Nobody on this message board asked about vibrating dampers, so I want to be the first.
I am trying to put new camshaft to my 440 and I noticed that somebody tried to pull out the damper using a hammer. There is a kind of flange on it and this flange is cracked in five places.
My engine is from '77 so the crank is casted and externally balanced and is not easy to find a new damper to this production year model. Do you have an idea where I can buy a new or used one (I checked BHJ and Mopar Perf. - they are VERY expencive)?
And also how to recognise casted from forged crankshaft?
Do you have some knowledge about dampers to share with me?
Maybe it is possible to give damper to machine shop and repair it?

Throw the damper away. It is not a part you can repair. We just discussed the differences between cast and forged cranks the other day. There is also at least one other older thread on this subject. Use the search facility in the left frame to find those threads. There must be quite a few of the engine builders in the USA that have used cast dampers lying around. Try them. I will have a look tomorrow and see if i can find an advert for one anywhere. All dampers are expensive if you buy them new.

Come to think of it... I think I might have one in my garage somewhere. I will have a look and get back to you.

OK I have one. BUT! Mine is fron a forged 440 with the heavy six-pack rods. It has holes drilled in it which I assume is how they fine-tuned the balance. I doubt it would exactly balance your crank.

I had a quick look in Mopar Action Magazine (a good source for adverts and products) and I see MAS Racing Products (651-644-6811, fax 651-644-1635) sell what looks like a cast crank damper for $170. I don't think you will find one much cheaper than that. It is chrome too!

Hi,
My problems never will finish!?
I have checked my damper again, compared it with photos from “Moparts” and now I am sure it is for steel crank. But my engine block was produced in ’78 so the crank should be cast. I’ve removed small cover from gearbox and I saw that converter has welded weights. It p.... me off so I removed the oil pan – and the crank is FORGED. OK. – it is not bad – it is better to have steel crank that cast. But....

Because I pull out the heads (I want to install new Hughes cam, springs, headers....), I decided to pull out the engine block and balanced the crank, rods and pistons.
And now is a time to ask a question:
1. Can I press out once again the pins from pistons – I did it once last year when I bought a new KB pistons and then, unfortunately I made a mistake and installed them “up side down”? Is there a possibility that pistons will damaged during pressing?
2. Forged crank is balanced on the balancing machine together with pulley, damper, and flex plate (like cast crank)?

Last year when I installed new pistons I should balanced rods and pistons but I didn’t do this so now I have last chance to do this. I don’t want to re-assembly the engine once again, but I am afraid of pin removal process.

I don't know how you are removing them but if done correctly with the right tool and press then it should not damage anything. At least that is my understanding. It is not a job I would try myself at home. Pay someone to do it. Then if one breaks they can replace it out of their own pocket.

You should take the pistons, rods, crank, damper, flex plate, and convertor to be balanced together. Although it may not be possible to do it with the converter. Best to ask the people that are going to do it. If you balance everything without the converter you should use a converter built for an internally balanced engine.

Dave, do you remember how my Challenger was vibrating when driving 90+ km/hr ?

I had my engine balanced when I got home to Norway. This DID NOT HELP AT ALL..... I had a forged crank,.....and after getting the converter balaced, 99% of the up/down-sideways vibrations were gone.
I want to stress, that the vibration damper at the front of the engine, is for torsional vibrations, and will of course not have any effect on vibrations caused by unbalance of the rotating parts.
A converter having balance weigths, used on an engine which have had it's induvidual components balanced,.....is the WORST possible situation.
That was exactly my situation back in -94.
The rubber mounts at engine and tranny was damaged by the continous vibrations,...and had to be replaced.
As for the small vibrations I still have, I assume that they are related to the fact that I'm yet to have the transmission vs rearaxle properly aligned. The angles at each cardan joint have to be equal, in order for the rotational speed to be uniform.

Consider this,...an ACCURATELY balanced engine is most important for high RPM applications,...as the forces generated is a function of RPM squared.
An unbalanced engine (Different piston weigths forexample)will generate less power, as the vibrational damper will consume some energy.

Good luck Jarek}, and keep us posted...

Of course I want to press out the pins in machining shop on hydraulic press.
But I am afraid that this process could squeeze the pistons too much and they can break. (As you know pistons are quite expensive). Do you have any experience with this? Press the pin out twice is not too much to them?
Or maybe it is not necessary (it is not worth) balancing pistons and rods - when I weigh it last year difference between the lightest and the heaviest was only 25 grams (1.3% of total weight)?
I know that total weight is only a part of this proces, but....

I will appreciate any advices

"Twisted" Jarek

I would get them to within a gram if possible myself. I am no expert in this but there must be a way to support the piston so that it does not get squeezed. Also I would think that if anything the pin would push out easier each time?

Piston's do not like to have the pins pressed out, most shops will state a no guarantee clause on the job because of the risk, pressing them on is not so bad because you can pre heat the piston to aid fitting. 25 grams is a bit too much for high rev's but o.k. for a street car I reckon

I'm not an expert, but I have the following experience from what is SOPPOSED to be a good workshop in Norway...
When I sent the parts to have them balanced, they charged me for having the connecting rods normalised (Heated to a specific temperature to get rid of resudual stresses etc..) That meant that they had to take the pistons off the rods...
The pistons where glass-blasted.
Ofcourse I had NOT asked for any of this work to be done,...but they claimed this was normal procedure....
Now,...I blew that engine up later that year,,,,My own fault from reving it too much...but I just LOVE the sound of V8's at high RPM...
Anyway, I had the 440 rebuilt. I guess it was blind luck, that i took the engine out 3 years later, and I found that one piston had cracked at the pin support. I had the shop send me a new piston...guess what,...after I pointed out that the piston was some 22 grams heavier,...they reverted with a letter saying it was OK for street use...
That piston could NOT be made ligther,...the shop had already removed material from the safe places.

I don't know at what RPM you plan to operate your car,...but I guess 25 grams is within "normal" for street use.
Like I said earlier, the vibrations I had, was because of the converter...

I knew there had to be an davantage to floating pistons. Now I know! there is something about balancing rods or pistons in this months Mopar Action which just fell on my door mat today. i will have a read of it tomorrow and see what it says.

340's have fully floating pistons, those engines rock!

Hang on. I just remembered something. I am sure my KB pistons did not have a press fit pin. They press into the rod end I think but the piston floated on the wrist pin. Maybe I am mistaken?

I had a look in my Mopar Action but it does not go into ant detail about balancing. The photos I saw were misleading. It is just an overview of the work carried out on a 440 for them by Ray Barton. That man sure can build an engine.

Dave,
Pistons have to float on pin - you are right.
I asked on "Mopar Mailing List" about balancing and they answered me:

"Although it is not necessary to balance a crank with the vibration
damper and torque converter / flywheel attached it is a VERY good idea.
That way you end up with a much better balance. When I have a crank
balanced I make sure that they balance the crank first then add the
damper and balance that, then add the flywheel or torque converter and
balance that. That way you know that the engine is internally balanced
so should you have to replace the damper or torque converter as long as
those pieces are properly balanced you should be vibration free. But
balancing the assembly will ensure just that much better balance and
less harmonic vibration."

Do you think that Dave Hughes can answer question about weight tolerances of pistons and to balance them or not?

If Alex thinks 25 grams is ok on a street engine then that is good enough for me. I am a picky person which is why I said I would try for 1 gram. I don't think I could actually get that close in practice. But I would be trying!

Starting with a good matched set is important. But with a piston/pin that possibly weighs around the 800gram mark I think Alex is most likey right about an engine seeing normal rpms not being that bothered about a 25 grams extra in one hole. But if you can get it closer it can only be better.

Dave Hughes is a very down to earth guy. His no-bull attitude to his work impressed me the first time I talked to him. Ask him if you like. It will not cost you anything. He has a lot of experiance with building and racing these engines.

Hi
I spoke with Dave and he told me that they put out and in pins from pistons, if it necessary, even many times. They have a special "fixture" to do this - kind of support which supported a small end of rod. Piston is not squeezed at all - the whole force is given to pin. He even sent me photos of this device.
I only have to prepare something similar and go...

Dave Hughes is really very nice and patient guy - he explain me very s l o w l y (and this is very important to me because English is not my native language) how it works.
I hope that all modification which I did and I will do in a few weeks, will change my engine into a real beast – ha ha ha - (CR 10.5:1, KB pistons, balanced engine, steel crank, Hughes cam 2330, Performer RPM intake, Edelbrock 750cfm carb...).
Jarek – the Optimist

Hello again,
After few month of driving a car with rebuilt engine it is time to make next "improvements".
I have in my car strange vibrations - they like sinus (or cosine ) curve on all engine and car speed. Vibrations are with low amplitude on low rpm and with very high amplitude on high rpm.
I have balanced a propeller shaft, wheels, but vibrations don't want to disappear.
Do you have any ideas?

I thought of a few things that might do it.

From the front back-over.

Bent crank pulley.
Damaged crank ballancer.
Bent con rods
Wrong spark plug firing order.
Broken flex plate
External balance damper or convertor on internal ballance crank.
Internal balance damper or convertor on external ballance crank.
Worn or missing pilot bushing with manual trans.
Worn bearings in trans (manual or auto)
Worn bush at end of trans output shaft.
Worn universal joints.
Badly lined-up propeller shaft/differential (pinion angle)

The last one was the main cause of my vibrations. Setting the pinion angle correctly makes a big difference if it has been far out. I describe doing this in my thread about fitting the overdrive. Your car did not come with a 440 so if the prop is shorter it could be at the wrong angle.

That gives you a few things to look at anyway.