Build update - 4T80 3800 Turbo (Page 8/10)
Trinten NOV 04, 07:27 PM
Thanks!

That makes perfect sense. I am confident that we have the shifter locks lined up pretty well with the detents. I wasn't sure which cable other guys who did the northstar w/4t80 swap was using, so we had messed with a few different Cadillac cables till we found one that worked. I didn't even consider buying a Fiero one to try. Hindsight is always 20/20!

Thanks again for the quick reply
zkhennings NOV 05, 10:24 AM
Car came out dirty (in a good way). Must feel good to drive it again after so long. Haven't driven mine since 2015, hoping to be driving it this upcoming summer.

Thought about any suspension mods to stop it from lifting the front?
LFiero67 NOV 05, 02:07 PM
First drive was a pretty cool feeling.

I want the front to lift to get all the weight on the back tires to help keep from spinning the tires. I may play with rear spring weight as it doesn’t seem to want to take as much power as it used to on the stock springs. Not sure if I need heavier spring to plant weight or lighter spring to help more weight transfer. At least with coil overs now, it’s fairly easy to try different things.
zkhennings NOV 11, 01:12 PM
I would imagine that a softer rear that squats more would help progressively load the tires and provide additional grip, compared to a soft front that extends. With a stiffer front but a softer rear you may still lift the front wheels and get 100% weight transfer, but the front won't have to come off the ground as far to accomplish this.

I haven't built a drag car, just contemplating the physics.
LFiero67 NOV 11, 07:51 PM
Probably try and find something similar to the stock spring at ride height, stock suspension worked extremely well, but limited tire size. Coil-overs have made more room, but don’t seem to be holding the tire as well. Going to throw a limited slip in and see if that helps as well.
Trinten NOV 12, 12:40 AM
There's a LSD for the 4T80?

Is it one of those "clutch" styles ones? I have mixed feelings on them for transverse transmissions, which is likely due more to my ignorance on transmissions. If anyone makes a helical/worm gear style LSD for it though... I'd be all over that.

EDIT: Found it, googled it and found the "Traction Concepts" one. I think I did see this before and passed on it because of it's style. A quick search didn't turn up any gear-driven ones yet though.

[This message has been edited by Trinten (edited 11-12-2024).]

Frenchrafe NOV 12, 04:52 AM

quote
Originally posted by LFiero67:

.... Not sure if I need heavier spring to plant weight or lighter spring to help more weight transfer. At least with coil overs now, it’s fairly easy to try different things.



I use a fairly "light" spring rate at the rear. Something like 250#, if I remember?

It penalises on body roll, but it helps to bog down the rear and grip!

------------------
"Turbo Slug" - '87 Fiero GT. 3800 turbo. - The fastest Fiero in France! @turboslugfiero
https://youtu.be/hUzOAeyWLfM

LFiero67 NOV 12, 08:08 AM
I agree, the style of LSD isn’t my favorite, but it just needs a little bit of help to keep from opening up. I generally will spin both tires in burnout box, and leave two black marks when breaking traction. Sometimes one wheel will stop spinning though, and the car does want to go left when the from tires come off the ground, which I suspect is due to more torque going to right wheel.

On the 4t65, I had the diff pin come loose a couple of times, which is from uneven burnouts. I’m going to give this a shot, hopefully it helps, if not it was relatively cheap.


I’m currently on 275 lb springs, but only 10” long. May try some longer ones to make sure I’m not running out of spring travel and upsetting the suspension.
Frenchrafe NOV 13, 04:26 AM

quote
Originally posted by LFiero67:

I agree, the style of LSD isn’t my favorite, but it just needs a little bit of help to keep from opening up. I generally will spin both tires in burnout box, and leave two black marks when breaking traction. Sometimes one wheel will stop spinning though, and the car does want to go left when the from tires come off the ground, which I suspect is due to more torque going to right wheel.

On the 4t65, I had the diff pin come loose a couple of times, which is from uneven burnouts. I’m going to give this a shot, hopefully it helps, if not it was relatively cheap.


I’m currently on 275 lb springs, but only 10” long. May try some longer ones to make sure I’m not running out of spring travel and upsetting the suspension.




I try not to do burnouts. Too much risk to break a shaft or blow the gearbox up!
I prefer semi slick tyres and low tyre pressures.
Here in France, most of the runs are on non-prepped surfaces (old aerodromes) so heating up the tyres with a burnout doesn't make much difference to your performance.
The others do it mostly for the show!

------------------
"Turbo Slug" - '87 Fiero GT. 3800 turbo. - The fastest Fiero in France! @turboslugfiero
https://youtu.be/hUzOAeyWLfM

LFiero67 FEB 16, 08:45 PM
After taking a look at videos of the launch, comparing pictures to old pictures I realized I have the suspension a bit lower than I did before. To the point that when I launched, I fully compressed the rear suspension, shocking the tires and causing the loss of traction. In addition, the 275lb springs feel like they compress easier than the stock setup did when I bounce the rear end by hand. I think I am going to increase the spring rate, to reduce travel during the launch, as well as likely flip the strut top mount to get the bump stop some more room. I would like to keep the car sitting how it does now, but get the suspension to work like it used to.

I have picked up a new garret 1000hp air to water core to re-core my old intercooler and also picked up a new turbo. Hoping to back to back the turbo on the dyno and will have more info about it when I do.

Picture of launch, just before loosing traction:



Ride height now:



Ride height 2016:



Compression now:



Compression 2016:

[This message has been edited by LFiero67 (edited 02-16-2025).]