Actually around town it drives great. I have tried to take good care of it since it got it with 140,000 miles. I do need to start looking for a good shop to either rebuild it or put a rebuilt one in it. Jasper engines does a lot of advertising in my area. I am thinking of going that way. Their website shows $1800.00. Of course I have to get someone to install it. Opinions?

1988 EB Bronco - 302 - AOD - 3.55 Limited Slip - Manual Hubs - BFG 32/11.5 AT - 208,000 miles

 

I have heard good and bad but thats usual for most engine manufacturers. ask around some of the shops to get a feel how they like jasper.

 

I'd do some thorough checking of emission/fuel/ignition components, and a tuneup first, unless you know for the fact that (i.e. compression readings) that the engine is significantly worn. Also, switching to 235/75R15 could help, too.

 

best way to figure correct gear ratio after tire size to get original performance is: new tire diameter divided by old tire diameter times original gears equals new gear ratio new diameter/old diameterXoriginal ratio=new ratio

 

Good "rule of thumb" calculation is to mutiply .12 by your tire diameter. (.12 X 38" = 4.56)
(see more formulas at bottom of page) The below table can be used to get a rough idea on gear ratios. The colors represent ideal RPM's at highway speeds (65). For highway cruising and best fuel economy stay towards the yellow (2600 rpm), around town daily driving is color coded green (2800 rpm), and for better towing power or just more 4-low power use the ratios near the red (3100 rpm). These calculations are assuming a manual transmission with a 1:1 ratio. If you drive an automatic your RPMs will be slightly higher, and the opposite is true if you have overdrive (your RPMs will be slightly lower).

<TABLE class=maintext cellSpacing=0 cellPadding=0 align=center border=1><TBODY><TR><TD align=middle bgColor=yellow> Better Gas Mileage </TD><TD align=middle bgColor=lime> Near Factory Ratio </TD><TD align=middle bgColor=red> More Power </TD></TR></TBODY></TABLE>
<TABLE class=maintext align=center border=0><TBODY><TR><TD></TD><TD align=middle>Gear Ratio</TD></TR><TR><TD vAlign=center align=middle>T
i
r
e


D
i
a
m
e
t
e
r
</TD><TD><TABLE class=maintext align=center bgColor=silver border=1 VALIGN="CENTER"><TBODY><TR bgColor=aqua><TD></TD><TD></TD><TD>3.31</TD><TD>3.42</TD><TD>3.55</TD><TD>3.73</TD><TD>3.91</TD><TD>4.11</TD><TD>4.27</TD><TD>4.56</TD><TD>4.88</TD><TD>5.13</TD><TD>5.29</TD><TD>5.38</TD><TD>5.71</TD><TD>6.17</TD><TD>7.17</TD></TR><TR></TR><TR><TD bgColor=aqua>27"</TD><TD></TD><TD bgColor=yellow>2677</TD><TD>2766</TD><TD bgColor=lime>2872</TD><TD>3017</TD><TD bgColor=red>3163</TD><TD>3325</TD><TD>3454</TD><TD>3689</TD><TD>3947</TD><TD>4150</TD><TD>4279</TD><TD>4352</TD><TD>4619</TD><TD>4991</TD><TD>5800</TD></TR><TR><TD bgColor=aqua>28"</TD><TD></TD><TD>2582</TD><TD bgColor=yellow>2668</TD><TD>2769</TD><TD bgColor=lime>2909</TD><TD>3050</TD><TD bgColor=red>3206</TD><TD>3331</TD><TD>3557</TD><TD>3806</TD><TD>4001</TD><TD>4126</TD><TD>4196</TD><TD>4454</TD><TD>4813</TD><TD>5593</TD></TR><TR><TD bgColor=aqua>29"</TD><TD></TD><TD>2493</TD><TD>2576</TD><TD bgColor=yellow>2674</TD><TD>2809</TD><TD bgColor=lime>2945</TD><TD>3095</TD><TD bgColor=red>3216</TD><TD>3434</TD><TD>3675</TD><TD>3863</TD><TD>3984</TD><TD>4052</TD><TD>4300</TD><TD>4647</TD><TD>5400</TD></TR><TR><TD bgColor=aqua>30"</TD><TD></TD><TD>2410</TD><TD>2490</TD><TD bgColor=yellow>2584</TD><TD>2715</TD><TD bgColor=lime>2846</TD><TD>2992</TD><TD bgColor=red>3109</TD><TD>3320</TD><TD>3553</TD><TD>3735</TD><TD>3851</TD><TD>3917</TD><TD>4157</TD><TD>4492</TD><TD>5220</TD></TR><TR><TD bgColor=aqua>31"</TD><TD></TD><TD>2332</TD><TD>2409</TD><TD>2501</TD><TD bgColor=yellow>2628</TD><TD>2755</TD><TD bgColor=lime>2896</TD><TD>3008</TD><TD bgColor=red>3213</TD><TD>3838</TD><TD>3614</TD><TD>3727</TD><TD>3790</TD><TD>4023</TD><TD>4347</TD><TD>5051</TD></TR><TR><TD bgColor=aqua>32"</TD><TD></TD><TD>2259</TD><TD>2334</TD><TD>2423</TD><TD bgColor=yellow>2546</TD><TD>2696</TD><TD bgColor=lime>2805</TD><TD>2914</TD><TD bgColor=red>3112</TD><TD>3331</TD><TD>3501</TD><TD>3610</TD><TD>3672</TD><TD>3897</TD><TD>4211</TD><TD>4894</TD></TR><TR><TD bgColor=aqua>33"</TD><TD></TD><TD>2191</TD><TD>2263</TD><TD>2349</TD><TD>2469</TD><TD bgColor=yellow>2588</TD><TD>2720</TD><TD bgColor=lime>2826</TD><TD>3018</TD><TD bgColor=red>3230</TD><TD>3395</TD><TD>3501</TD><TD>3561</TD><TD>3779</TD><TD>4093</TD><TD>4745</TD></TR><TR><TD bgColor=aqua>34"</TD><TD></TD><TD>2126</TD><TD>2197</TD><TD>2280</TD><TD>2396</TD><TD>2512</TD><TD bgColor=yellow>2640</TD><TD>2743</TD><TD bgColor=lime>2929</TD><TD>3135</TD><TD bgColor=red>3295</TD><TD>3398</TD><TD>3456</TD><TD>3668</TD><TD>3963</TD><TD>4606</TD></TR><TR><TD bgColor=aqua>35"</TD><TD></TD><TD>2065</TD><TD>2134</TD><TD>2215</TD><TD>2328</TD><TD>2440</TD><TD bgColor=yellow>2565</TD><TD>2664</TD><TD bgColor=lime>2845</TD><TD>3045</TD><TD bgColor=red>3201</TD><TD>3301</TD><TD>3357</TD><TD>3563</TD><TD>3850</TD><TD>4474</TD></TR><TR><TD bgColor=aqua>36"</TD><TD></TD><TD>2008</TD><TD>2075</TD><TD>2154</TD><TD>2263</TD><TD>2372</TD><TD>2493</TD><TD bgColor=yellow>2590</TD><TD>2766</TD><TD bgColor=lime>2961</TD><TD>3112</TD><TD bgColor=red>3209</TD><TD>3264</TD><TD>3464</TD><TD>3743</TD><TD>4350</TD></TR><TR><TD bgColor=aqua>37"</TD><TD></TD><TD>1954</TD><TD>2019</TD><TD>2095</TD><TD>2203</TD><TD>2308</TD><TD>2426</TD><TD bgColor=yellow>2520</TD><TD>2692</TD><TD bgColor=lime>2881</TD><TD>3028</TD><TD bgColor=red>3123</TD><TD>3176</TD><TD>3370</TD><TD>3642</TD><TD>4243</TD></TR><TR><TD bgColor=aqua>38"</TD><TD></TD><TD>1902</TD><TD>1966</TD><TD>2040</TD><TD>2144</TD><TD>2247</TD><TD>2362</TD><TD>2454</TD><TD bgColor=yellow>2621</TD><TD>2805</TD><TD bgColor=lime>2948</TD><TD>3040</TD><TD bgColor=red>3092</TD><TD>3282</TD><TD>3546</TD><TD>4121</TD></TR><TR><TD bgColor=aqua>39"</TD><TD></TD><TD>1854</TD><TD>1915</TD><TD>1988</TD><TD>2089</TD><TD>2190</TD><TD>2302</TD><TD>2391</TD><TD bgColor=yellow>2554</TD><TD>2733</TD><TD bgColor=lime>2873</TD><TD>2962</TD><TD bgColor=red>3013</TD><TD>3198</TD><TD>3455</TD><TD>4015</TD></TR><TR><TD bgColor=aqua>40"</TD><TD></TD><TD>1807</TD><TD>1867</TD><TD>1938</TD><TD>2037</TD><TD>2135</TD><TD>2244</TD><TD>2331</TD><TD>2490</TD><TD bgColor=yellow>2664</TD><TD>2801</TD><TD bgColor=lime>2888</TD><TD>2937</TD><TD bgColor=red>3118</TD><TD>3369</TD><TD>3915</TD></TR><TR><TD bgColor=aqua>41"</TD><TD></TD><TD>1763</TD><TD>1822</TD><TD>1891</TD><TD>1987</TD><TD>2083</TD><TD>2189</TD><TD>2275</TD><TD>2429</TD><TD bgColor=yellow>2599</TD><TD>2733</TD><TD bgColor=lime>2818</TD><TD>2866</TD><TD bgColor=red>3042</TD><TD>3287</TD><TD>3819</TD></TR><TR><TD bgColor=aqua>42"</TD><TD></TD><TD>1721</TD><TD>1778</TD><TD>1846</TD><TD>1940</TD><TD>2033</TD><TD>2137</TD><TD>2220</TD><TD>2371</TD><TD>2538</TD><TD bgColor=yellow>2668</TD><TD>2751</TD><TD bgColor=lime>2798</TD><TD>2969</TD><TD bgColor=red>3208</TD><TD>3728</TD></TR><TR><TD bgColor=aqua>43"</TD><TD></TD><TD>1681</TD><TD>1737</TD><TD>1803</TD><TD>1894</TD><TD>1986</TD><TD>2087</TD><TD>2169</TD><TD>2316</TD><TD>2479</TD><TD bgColor=yellow>2606</TD><TD>2687</TD><TD bgColor=lime>2733</TD><TD>2900</TD><TD bgColor=red>3134</TD><TD>3642</TD></TR><TR><TD bgColor=aqua>44"</TD><TD></TD><TD>1643</TD><TD>1698</TD><TD>1762</TD><TD>1851</TD><TD>1941</TD><TD>2040</TD><TD>2119</TD><TD>2263</TD><TD>2422</TD><TD>2546</TD><TD bgColor=yellow>2626</TD><TD>2670</TD><TD bgColor=lime>2834</TD><TD>3063</TD><TD bgColor=red>3559</TD></TR></TBODY></TABLE></TD></TR></TBODY></TABLE>

 

this chat is great if you have a 4speed manual or 3speed c-6. if you have an AOD or E4OD then it will be a bit different

 

thats why it works to use the other forumula i had up. new diameter/old diameter X old ratio

 

What's interesting about that chart is, is that I'm running 33x12.50x15's with 4.11 gearing and can maintain 65mph at less that 2200 rpm's. That's more than 500 rpm's less than the chart is showing. Am I reading somethig wrong here? I was mildly concerned when I went to 33's about mileage, but it hasn't really changed from the 31's that were on it.
On a side note about your switching gears, if your going to 3.73's front and rear, should the front be slightly differently geared? My front axle is 4.09. Maybe that set-up is standard from the factory and swapping gears later to the same ratio's is normal/proper. Just wondering.

 

Are you saying you had the 4.10s on with 31s then went to 33s? It would be fine to have gear ratios like that, 4.10 and 4.09 or 4.11, that little difference won't heart.

 

Exactly. That's what I'm saying. 31's with 4.11/4.09 is ok I guess, but it's good to know that I'm more in line with 33's with those gears. As I understand things.
Having the different gear ratio's between the two axles is the reason it is not recommended to run in 4WD on dry pavement. On "dirt", the axles are allowed to "slip" when necessary to keep from binding up.
(thread hijack over)

 

Your 4.10 gears are about right for your 33s(3.73 is a little closer), you could even go to 35s with 4.10s, and be fine, but right now it's a little high, but that wont cause any problems. A good off road set up.

-Matt

 

a good offroad setup is to gear over what you need. so for 33's run 4.56 for 35's run 4.88 etc... 35's and 4.10s would be ok if your running a C6 for hwy use but still to tall for offroading