[tonylsg]

I am fixing to have the rear end rebuilt on my 85 street/strip silverado. It is a 10 bolt 8.5" rear end. I have found a reputable shop that everyone in this area uses. It is going to cost me about $420 for gears, bearings, and installation. I would like advise on the following (preferrably from people using or having used comparable set ups). I can not decide on what ratio to run 3.73 or 4.11's. The truck will spin both tires in the rain but on dry pavement it will only spin one tire until about 50mph then the other one comes in. i have heard that lower gears will help get both spinning of the line(my primary concern), or maybe installing stiffer clutches.. The guy recommended putting and EATON posi unit in for an additional $320. I just can not afford to pay $740 for this set up. so i am considering sacrificing some of its street ability and putting in a spool. I would appreciate some advise on this decision.
truck info:
1985 silverado 3500lbs with driver, 364 cubic inch sbc motor, (487 heads)75cc LT1 heads from 1971 2.02 and 1.60 valves, crane 480 lift, 274 dur. cam, edelbrock performer intake and 600 carb with 1 inch spacer, hedman full length headers, th350 transmission with 2000 stall and 28 inch tires. the truck is in the process of going mostly strip but still legal (not a daily driver).Searching for mid 8's in the 1/8 mile, but only for now
tried this post in the trans-rear section and got nothing.

[cuda66]

not always is the lower gear better. I have a 3.55 and a spool in the cuda. I don't really like the spool because I don't like the thought that I have to buy tire so often. How soon is the truck going to be put on the track permanatly??? Just to let you know I have almost finished mine and gotten it tuned out and i am pushing around 425 to 450hp from the motor I will only running some where in the realm of 8.25 in the 8th mile. and around 12.5 in the quarter. not bad considering the 318 motor. but as far as the spool is concerned pay the extra money and get a limited slip rearend and and put a normal gear 3.23 or 3.55 in it so that you can enjoy it and smoke some people on the street if you go like 411 or 373 when crusing on the street you will be some where around 3500-4000 at 70 mph and the gas stations will love you. 740 dollars is cheap. ( I understand every one has a budget but do it right the first time and forget about it) I paid that and had to set up the rear end myself!!! now that is the gear all the berrings and races and the spool and the gear and all the gaskets and the seals. If you are thinking of purchasing a spool save you time and make friends with a welder and weld up your spider gears in the open carrier. alot of people that you talk to would probably disagree but I dont think that you will have enough hp to brake it loose if the welder knows what they are doing.

[tonylsg]

The motor is pushing about 377 h.p. and i am expecing about 8.7 in the eighth. I have a formula to compute the mph at a certain rpm or vise versa. I am looking at at 2900rpm at 60mph with 4.11s and 3900 at 80mph. The 3.73s will be something like 2500 at 60 and 3600 at 80. These maybe slightly off i am recalling from memory. The cam card suggests atleast 2500 at 60. I run a 28 inch rear tire that really drops the rpms. I think i may get the cluthces replaced to make it lock in better, since it is traction lock system (limited slip). Just a suggestion another racer gave me. I just can not decide on a ratio, need to hurry though making appointment in the next week or two to get it done. The truck will be all strip in about 1.5 to 2 years. Trying to finish college. I just cruise on weekends right now and do my commuting in a 4 banger.

[ February 17, 2003: Message edited by: tonylsg ]</p>