Single best/first performance mod

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drobs5

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Just curious what all the mark viii experts think the single best performance mod (tune, gears, torque converter, etc) starting off is for these cars (with power adders included and without power adders included)? I bought one a few weeks ago and love it thus far but I must say that it feels slower than I expected. With that said, this is my first modular powered car (other than the coyote powered 11 GT I sold a year ago which is no comparison) so maybe I am more just used to the torquey feel of a small block ford.
 
What year is your car btw and how many miles?

I like to change the transmission fluid (mercon v only) and filter to make sure the transmission will live under all the 'mods' and the expected 'performance' driving. I recommend doing the jmod (shift kit) at the same time to increase durability and responsiveness.

Cleaning the maf sensor with electrical contact cleaner or maf cleaner and a q tip (very gently) will restore lost performance very cheaply.
 
This probably goes without saying but since you just bought the car, you might want to change the spark plugs. Worse case scenario they might still be the original platinums...

As for performance mods... 3.73 or higher gears with traction lock and a requisite tune unlock the potential of these cars.
 
Most on here will say gears and trac lok, or a converter. I put 4:10's and a trac lok in my 94, felt like a different car. Totally worth it
 
A tune up is a given ... will work on that this weekend. I have both a 3.73 and 4.10 gear w/posi center section in the garage so I'll have to decide between the two.

I see a lot of people mentioning the j mod. I'll have to research that to see what it is exactly. I assume it has something to do with the trans as the stock trans shifting it sooooo mushy. Does the j mod provide additional features/performance over adjusting the shift pressures and such with a tune?
 
drobs5 said:
I see a lot of people mentioning the j mod. I'll have to research that to see what it is exactly. I assume it has something to do with the trans as the stock trans shifting it sooooo mushy. Does the j mod provide additional features/performance over adjusting the shift pressures and such with a tune?
Click to expand...
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there's a tab up top, 'tech articles'...lotsa good stuff there, here is the jmod page, click
 
drobs5 said:
A tune up is a given ... will work on that this weekend. I have both a 3.73 and 4.10 gear w/posi center section in the garage so I'll have to decide between the two.

I see a lot of people mentioning the j mod. I'll have to research that to see what it is exactly. I assume it has something to do with the trans as the stock trans shifting it sooooo mushy. Does the j mod provide additional features/performance over adjusting the shift pressures and such with a tune?
Click to expand...

It supposedly makes the transmission fluid run a little cooler because you're making the holes bigger in the separator plate of the valve body. Increases the durability, quickens the shifts. I believe it's best to have a jmod and a tune. You don't have to increase the line pressure as much in the tune to get the same results and after a point too much line pressure can cause damage to the transmission.

Since you have a '97 transmission it's recommended to replace the 1-2 and 2-3 accumulator pistons in the transmission for the later improved design pistons if they haven't been replaced already.
 
dnsherrill said:
93-97 mark VIII 4r70w's are all the same?
Click to expand...

98 and up have the improved design rubber accumulator pistons I believe. 1997 and earlier do not. The 98 and up transmission is better internally as well.

From what I've read 93, 94 and 95 transmissions are the weakest. 1996 and 1997 is better. 1998 is much better

When you do a jmod make sure you use the instructions for your model year transmission
 
opalescent 96 said:
98 and up have the improved design rubber accumulator pistons I believe. 1997 and earlier do not. The 98 and up transmission is better internally as well.

From what I've read 93, 94 and 95 transmissions are the weakest. 1996 and 1997 is better. 1998 is much better

When you do a jmod make sure you use the instructions for your model year transmission
Click to expand...

i concur. the 96 got some main control/valve body updates, and the 98 got the one way clutch upgrade.
that said, my 93 trans lasted to 170k under my heavy right foot. not a weak trans per say, just could be better.

also, if putting a 98 or newer trans into a pre 97 car, you will need to repin the wiring connector as well, as the pin out changed in 98.

the JMOD works by enlarging holes in the separator plate, this allows quicker fluid movement without raising the line pressures and stressing the front pump. it is essential for good trans performance and lifespan. and you can change the fluid and the accumulator at that time as well.
 
I thought I had read somewhere that the 98 models had the trans upgradeyou mentioned but late year 97 models had it as well. Is that correct? If so, how do I identify which I have?
 
o.p, you mentioned there's no way your 97 could lay down rubber b/c it's a 'turd'?......do you think it's running as it should? or is it just too mellow for you?
 
dnsherrill said:
o.p, you mentioned there's no way your 97 could lay down rubber b/c it's a 'turd'?......do you think it's running as it should? or is it just too mellow for you?
Click to expand...

Seems likes it's running good .... no codes or anything (unless the CEL light has been tampered with) but I don't see or feel anything to tell me it's not running up to par. I stopped on the interstate on ramp (of course in Mexico lol) one night, turned off the traction control and just stomped the gas. It spun the right rear a couple times and then just took off. Without braking, there's no way my car currently would lay down a strip of rubber like I saw in another thread. It just doesn't feel very torquey to me. It feels like you really have to rev it to make any power which is why I figured a gear was one of the top mods for these cars.

I have a regular cab, 95 shortbed f150 5.0/4r70w with an open 3.31 rear that feels like it would destroy the Mark as it currently sits stock. Of course it has a few mods, worked 289 heads, cam, long tube headers and a tune but still.

Maybe my butt dyno isn't that accurate though lol.
 
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