A while back I started a project of changing the rear end in my 91 auto convertible. It had the GM1 2.59 gears I have now changed them out to 3.54 gears and put on c5 wheels 275/40/zr18. A fellow forum guy was great about helping with the speedometer gear changes (he was wvzr1 or something close) but I can no longer find that thread or where I put the info. Can anyone help with the correct drive and driven gears, and if I remember right you have to turn the driven gear 180 degrees to put on the new gear.

 

That was likely ME - What do you have for the drive and driven now? The aggravating change in these presently is the availability of parts. In years past I never advised or mentioned using a DRA in place of the correct mechanical correction but in all honesty it's maybe what might need to be considered. I'm nearly out of all of the drive driven combinations and I think I've only one early VSS (which you wouldn't need) left.

Tell me what you've got and we'll start fresh. Did you buy any parts at all?

 

I do not have it apart yet but whats on there is what came from the factory. I have purchased a 43 tooth 700r4 driven gear and a 15 tooth drive gear from american hot rods but I looked at the driven gear since it is easy to get off and it looks like it won't fit properly. If I go with a DRA is there one you recommend ?

 

I had a good result, albeit with a mechanical box in an older car, comparing the dash speed to GPS. That dictated to my speedo shop how much change was needed.

 

If you've done the gear change and left the 18 tooth (likely) in the transmission then the change to the 15 tooth (required) is going to be somewhat labor intensive. That might be more of an argument for the DRA. The 43 tooth you've bought has a shaft on it OR a D shaped hole that would fit the VSS you bought?

Under my user ID is an email option. Send me snapshots of the gears you've bought.

Years ago I did a couple projects and used SPECMO DRA for each. I doubt that SPECO does them any longer but it might be worth a check. Abbott is a very old/reliable instrument vendor and I'd maybe use them but theirs is likely the more expensive option. Dakota-Digital is what many use now and most are more familiar with, SLP used DD products years ago and had problems, the FOMOCO guys I believe did also but in the past several years I've seen no issues BUT I haven't used them either. I generally mentioned avoiding them when asked.