Success! Transplanting a '92 LT1 Instrument Cluster in a '91 L98! Pics inside
 

Hi all,

A while back I posted a video of my idle. One user noted that the idle was reading very high, while sounding like a lower speed. I bought a ALDL USB cable and did some datalogging with my laptop. I found that my '91 instrument cluster was reading about 2X or more higher than the actual RPM. I decided I'd rather take the chance with the cluster than try and change the tachometer filter deep in the engine bay. I researched the forums and posted a WTB and info thread. The inaccurate tach had never bothered me before, when I was oblivious to the problem. However, as soon as I became aware, I had to have it fixed!

I ended up with a '92 LT1 instrument cluster from a forum member, received it on Thursday, and just installed it last night. It took me about 3 hrs total. The new (to me) cluster is spot on. I also like that the gauges have more ticks, making it easier to guesstimate the values.

I swapped the LCD out of my '91 because I had read the LT1's display the MPH on the top, and fuel level on the bottom - this is the reverse of the '90 and '91 readings. The mileage is displaying correctly and the lights and warnings seem brighter.

I'll probably make a thread or add to this one for a DIY with all the pictures I took. It was really simple - just plug and play. No modifications were needed, excepting the LCD swap for personal preference. I also cleaned all contacts with alcohol as well as the transplant cluster gauge faces. It looks much better than the original.

Some pictures:

Rear of the new cluster (all screws in cluster are T-15):
http://i290.photobucket.com/albums/l...r/102_6905.jpg

New Cluster Lens Removed:
http://i290.photobucket.com/albums/l...r/102_6917.jpg

LT1 Cluster Face & LCD:
http://i290.photobucket.com/albums/l...r/102_6918.jpg

Removing the LT1 LCD - As easy as pulling it out (no screws):
http://i290.photobucket.com/albums/l...r/102_6921.jpg

LT1 LCD & Color Backing for turn signal/high-beams/speed:
http://i290.photobucket.com/albums/l...r/102_6924.jpg

Taking the LT1 cluster apart further for fun:
http://i290.photobucket.com/albums/l...r/102_6928.jpg

The Old L98 Cluster:
http://i290.photobucket.com/albums/l...r/102_6929.jpg

Removing the hush panel:
http://i290.photobucket.com/albums/l...r/102_6945.jpg

Hush panel light and ALDL connector disconnected:
http://i290.photobucket.com/albums/l...r/102_6951.jpg

Removing the silver panel so I can access the 2 steering wheel support bolts (15mm head, torque to 20ft-lbs) to lower the steering wheel/column:
http://i290.photobucket.com/albums/l...r/102_6951.jpg

Steering Wheel Column Support Bolts/Bracket:
http://i290.photobucket.com/albums/l...r/102_6970.jpg

Steering wheel lowered, now we can remove the 4 screws attaching the old cluster to the car:
http://i290.photobucket.com/albums/l...r/102_6976.jpg

Cluster Removed:
http://i290.photobucket.com/albums/l...r/102_6983.jpg

L98 (top), LT1 (bottom):
http://i290.photobucket.com/albums/l...r/102_6986.jpg

LCD Swapped Out, Everything else is from the LT1 cluster, except for the lens (used the original):
http://i290.photobucket.com/albums/l...r/102_6995.jpg

Installed in the car:
http://i290.photobucket.com/albums/l...r/102_6999.jpg

Video:


The beeping is the hard-wired Valentine One starting up. (Wow, I sound weird on a video :lol:)

I'm going to hook up my laptop and verify its accuracy.

-Jonathan

Very cool indeed !!! Question: How hard was it removing the "silver panel" ? On my '94, it looks like I would have to remove tunnel carpeting to get at some botls that are recessed(ie can't be seen)

just curious.....

:thumbs:

You're talking about the 2 bolts next to the tunnel? I was able to access them without issue. They were a bit close to the tunnel trim, but I used an extension on my 1/4" ratchet. When removing the silver piece, you'll need to unscrew the 2 bolts holding the air duct in place. These are 2 small screws that are at the end of the silver piece. Then you can pop the air duct out. When reinstalling, leave these unscrewed, pop the air duct in, THEN maneuver the piece in and install the 4 screws holding the silver piece on.

Video added to the first post - that beeping is the hard-wired V1 starting up.

-Jonathan

:cheers:
Looks good.
Check to see if some of those trouble codes you're getting go away with the new cluster in there.
:thumbs:

Definitely. I think I'm having some trouble with converter lock-up too (getting 12 MPG!!!), but I'll work on that next week.

:thumbs:

I was thing of doing this swap. The tach on my 91 is way off. I like the higher red line (orange line).

Please keep us posted on the lock-up issue.

Do the swap - you won't be disappointed. I just took it out for a run and realized that what I thought was redline was only 2500 RPM!!!! It was off the old tach at the same sound level/accelerator travel. Gosh, this is a corvette now.

Wow, you thought you were redlining when the motor was at 2500? Now you have a whole 3000 or so rpm to play with. No more short shifting.

Nice job Jonathan. The pics came out great. If anybody plans on doing this and needs a cluster, drop me a line. :cheers:

:cool::cheers:

:cool:

:thumbs:

Nice work!:thumbs:

Good Job! :cheers:

I just did that on my 90 a week or so ago except I used a ZR1 tach instead. Same basic deal tho.

I didn't see you rev to check the rpm

Is it more accurate now? I remember noticing that on your thread a while back

Good work ,this post well be a good reference post..

Yep, it is VERY accurate. I hooked up my laptop and ALDL cable to check. I also notice that my oil pressure doesn't seem so low now at hot idle. I think that, as some suggested, the old cluster may have been reading the oil pressure inaccurately too. I have some videos of some runs and exhaust notes I think you guys will appreciate. :thumbs:

383vett - Yea, it was :crazy: - thinking I was redlining it at 2500!!! Now I truly appreciate the Corsa cat-back - its presence is more known at a true 4000 RPM...

Ramrod92- Thank you! If anyone has a need for an early Lt1 tachometer, definitely contact Ramrod92.

For those with a '90 or '91, with an inaccurate tach, I would definitely consider this swap. The LT1 has brighter lettering and more deviations in the gauges.

Thanks to everyone else for the comments,

-Jonathan

Thanks for the plug. Here's why I have my stock cluster out. http://forums.corvetteforum.com/c4-t...h-in-92-a.html :cheers:

Cool thread...but my steering wheel looks better than yours!:thumbs::lol:

glad the cluster worked for you