Q:

Role of drift in evolution of sexually dimorphic traits

Is there a model for predicting how drift can affect the evolution of a sexually dimorphic (SD) trait? I've been trying wrap my mind around this paradoxical question; sexually dimorphic traits evolve due to sex-specific selection. So how can drift affect SD traits?
I've found the quantitative genetic equations (eq 1) in Lande 1980 very helpful for thinking about the parameters and how sexual dimorphism evolves. 
Can this model be applied to a population bottleneck? Or comparing the degree of SD in a trait of two divergent populations (assuming s, Ne and other parameters remains constant).
$$
\begin {pmatrix}
\Delta z\\
\Delta y\\
\end{pmatrix}
= {1 \over 2}
\begin{pmatrix}
G_m B \\
B^{T} G_f\\
\end{pmatrix}
\begin{pmatrix}
P_m^{-1} s_m\\
P_f^{-1} s_f\\
\end{pmatrix}
$$
Edit: I've added the equation from Lande 1980, which models the phenotypic response for sexually dimorphic traits. I'm wondering how aspects of drift (Ne and fixation probabilities) can be merged with an equation such as this. From my understanding drift may affect the G, B and P matrices (that is the Genotype variance covariance, intersex (B) variance covariance and Phenotype matrices. One of the assumptions of this equation is that these matrices remain constant.

A:

[C]an drift overcome sexual selection in the evolution of sexually dimorphic traits?

Short answer
Yes
Long answer
There are many ways to consider the effect of genetic drift. Here is one: One can approximate the probability of fixation of new mutations (using diffusion equations) with 
$$P_{fix}≈\frac{1-e^{-4Ns} }{1-e^{-4s}}$$
, where $s$ is the selection coefficient and $N$ is the populations size. As you can see, a larger population size (the lowest is the genetic drift) corresponds to a higher probability of fixation of a beneficial mutation (to reach frequency of 1 in the population). If you don't have a good intuition of why genetic drift is inversely proportional to the population size, please have a look at this post. The most important point to keep in mind about the effect of drift is that when drift is high, every mutation pretty much behaves like neutral mutations.
This approximation is accurate under some assumption, for instance that the population is panmictic (=random mating). This equation holds true regardless of the reasons why a mutation affects fitness. The mutation may affect the activity level of an enzyme or it may influence how attractive an individual is to the other sex. So yes, in any case, a beneficial mutation may fix although it is deleterious (because of drift), or it may not fix although it is beneficial (because of drift).
A mutation might be beneficial in both sexes, detrimental in both sexes or beneficial in one sex and not in the other. In such cases, I suppose it is possible that the above equation must take a slightly different form. In any case where the mutation has a different impact on the fitness in each gender, I don't know how the above formulation would solve to but I'd think that you could simply replace $s$, by $\frac{s_m+s_f}{2}$, that is the average of the effect in both sexes (where $s_m$ and $s_f$ are the selection coefficients in males and females respectively). Intuitively, I think this should hold true as long as the sex-ratio is 1:1. The exact calculation of the probability of fixation doesn't matter to your question though. Note that mutations having the opposite effect on fitness in each gender often end up being on sexual chromosomes (if any) or at least being expressed in one sex but not in the other. In such case, a fixed mutation often end up being beneficial in one sex while neutral in the other. In any case, genetic drift will obviously affect the evolution of sexually dimorphic traits.
EDIT

could you clarify "As you can see the highest is the population size (the lowest is the genetic drift),"?

The impact of genetic drift can be measured in terms of how it affects probability of fixation or how it affects the rate at which heterozygosity at a neutral site is lost. An intuitive explanation for why $N$ and genetic drift are inversely proportional can be found here.

Are you referring to the positive correlation with P fixation and Ne?

Yes. I could have referred to that as to something else though. Note that the correlation between $P$ ans $N_e$ is perfect ($r^2=1$) because $N_e$ is defined on the concept of genetic drift.
Definition of $N_e$
Let's WR (stands for Wright-Fisher) be a population of size $N_{WR}$ where mating is random and there is no variance in fitness.
Consider now the population A. Let's its size be $N$. A experiences a given level of genetic drift based on its mating system, population structure, variance in fitness, etc.. the effective population size $N_e$ of A is (by definition) the size of the WR population ($N_{WR}$) that experiences the exact same level of drift, that is the same probability of fixation for a new mutation and the same rate of heterozygosity lose at a neutral site.

